NC0082139_Lagoon & Future Flow Estimations_20191205

Hazen Memorandum
E
Re: Lagoon and NPDES Future Flow Estimations REC
DEC 0 5IV 2019E D
• Residuals Flow Estimations NCDEQIDWRINPDES
o Typical Operation
• Scenarios:
• Scenario 1: Average flow(21 mgd), average solids loading(300 lb/MG)
• Scenario 2: Average flow(21 mgd), maximum month solids loading
(500 lb/MG)
• Scenario 3: Maximum month flow(30 mgd), average solids loading(300
lb/MG)
• Operational Conditions
• 100 hour filter run times
• 1 sedimentation basin blowdown per train per day
• 1 hour Superpulsator cycle run times
o Increased Residuals Operation
• Scenarios
• Scenario 4: Maximum month flow(30 mgd), maximum week solids
loading(570 lb/MG)
• Scenario 5: Maximum month flow(30 mgd), maximum month solids
loading(500 lb/MG)
• Operational Conditions
• 60 hour filter run times
• 1 -2 sedimentation basin blowdowns per train per day
• 1 hour Superpulsator cycle run times
o Add Contingency for Clearwell and Basin Draining
• One Clearwell=3 MG
• One SuperP=0.5 MG
• 3.5 MG averaged over 30 days=0.12 MG
o Max Month Flow and Max Month Loading plus contingency for clearwell and basin
draining=0.97 MG
*does not include any stormwater discharge to lagoon
Solids Average Flow Average Flow Max Month Max Max
Production: Avg Loading Max Month Flow Month Month
Loading Avg Loading Flow Flow
Max Week Max
Loading Month
Loading
$ Scenario 1 2 3 4 5
N Volume(MG): 0.52 0.52 0.57 0.93 0.85
0
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Hazen and Sawyer•4011 WestChase Boulevard,Suite 500• Raleigh, NC 27607•919.833.7152

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RECEIVED
DEC 05 1019
NCDEQIDWRINPDES
Hazenwww.hazenandsawyer.com

TURB CURRENT
pH/TEMP pH/TEMP PAC
CURRENT j POLYMERJ POLYMER' i POLYMER pH/TEMP
AS TURB
Cl© Ter
M M M III
M M M M
V
PRE-OZONE //
CONTACTOR J
/ i 0 pH/TEMP
PLANT METER VAULT IT / ....Ti RAPID MIX FLOCCULATORS = ��� TO LAGOON OZONE ,
i I I CAS
(2 MIXERS) (3 STAGE) S RESIDUALS SH
0
SEDIMENTATION O
F. CAS BASINS (6 BASINS)
SP I
CAS I
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!!! TO FILTERS
u PLANT INFLUENT
FROM TAR METER VAULT 2 POLYMERI
RIVER RW METER PRE-SETTLING
/ VAULT 2 IMPOUNDMENT o G VACUUM PUMPS(2)
AS I TURB
RAW WATER PUMP STATION I PH/TEMP
(4 PUMPS-1 NEW, 3 EXISTING) M TO LAB
IINTERMEDIATE OZONE
(4 CONTACTORS) LEGEND
S TO LAGOON AS ALUMINUM SULFATE
pHTO LABP 1 - (6)
CAS SODIUM HYDROXIDE
TO RAPID MIX SUPERPULSATOR
(2 MIXERS) T (1 BASIN) HF FLUORIDE
SP SODIUM PERMANGANATE
pH SH SODIUM HYPOCHLORITE
AH AQUEOUS AMMONIA
CI CORROSION INHIBITOR
PAC POWDERED ACTIVATED CARBON
TRIO CALCIUM THIOSULFATE
I TO LAGOON POLY POLYMER
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EXISTING CHEMICAL
i -I\TI- APPLICATION POINT
I EXISTING CHEMICAL SECONDARY
I APPLICATION POINT
1----FREE NH3 _� NEW CHEMICAL APPLICATION
I SH I TOTAL NH3 POINT
El MONOCHLORAMINE FREE NH3
I NEW CHEMICAL SECONDARY
t TOTAL CL TOTAL NH3 I
I I CAS P MONOCHLORAMINE
FREE C 1 APPLICATION POINT
FROM OZONE O O C SH FREE Cl TOTAL CL
TURB lyl MOTORIZED VALVE
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pH/TEMP HF © OS I SH _I I� PNEUMATIC VALVE
MONOCHLORAMINE 9 T
TURB CLEARWELL TOTAL CL 1 AH J1
• a 0 ' S r METER VAULT 1 5 TO LAB --- ❑
... `l _ _ Y INSERTION MAGNETIC FLOW METER
VENTURI FLOW METER
u 1� 510'STESTRIBUTION O SAMPLE
FILTERS ❑ 0 CLEARWELL
' (7 FILTERS) METER VAULT 2 ^
1 ' ( SAMPLE PUMP
El _ FINISHED WATER BUTTERFLY VALVE
PUMP STATION
/ SH ( CAS ��yyyy�� PLUG VALVE
GROUND STORAGE TANKS (4 PUMPS) Ma
SH (3 CLEARWELLS)
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pH/TEMP E.-TURB or FREE CL I
TURB FREE CL FLUORIDE TRIO J
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A limo
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..1, (4 FILTERS) TO TAR RIVER
PLANT AIR
CLEARWELL PUMP
STATION(3 PUMPS)
L.... PROJECT
y-- ENGINEER D.BRILEY DATE: 2019
- DESIGNED BY S.GIBSON GREENVILLE UTILITIES COMMISSION HAZEN No.: 31218-003
i. K PRELIMINARY DRAWING . Hazen GREENVILLE, NORTH CAROLINA GENERAL
DRAWN BY. J.JORDAN r------- , CONTRACT NO.: 01
CO NOT USE FOR EDHSEu a MECHANICAL
At-- ) CHECKED BY: D.BRILEY CONSTRUCTION HAZEN AND SAWYER DRAWING
F THIS BAR DOES NOT 4011 WESTCHASE BOULEVARD,SUITE 600
WATER TREATMENT PLANT PROCESS FLOW DIAGRAM NUMBER:
_ MEASURE T'THEN DRAWING IS ° 1 RALEIGH,NORTH CAROLINA 27607 PHASE 1 IMPROVEMENTS G07
ISSUED FOR DATE BY NOT TO FULL SCALE

RECEIVED
DEC 0 5 2019
NCDEQIDWRINPDE$

Hazen
Table 1-2: Sedimentation Basin Blowdown Sampling Plan
Location Parameter Frequency
Basin 1 TSS
Sed Basin Drain Vault 1
Basin 2 TSS
Sed Basin Drain Vault 1
Basin 3 TSS Every 10 minutes
Sed Basin Drain Vault 1 during a full
Basin 4 TSS blowdown event
Sed Basin Drain Vault 2
Basin 5 TSS
Sed Basin Drain Vault 2
Basin 6 TSS
Sed Basin Drain Vault 2
It is recommended that this sampling plan be carried out once. Samples should be taken during typical
solids loading conditions and in the course of one evening when blowdowns are typically initiated.
Sampling Plan Page 2

Hazen Memorandum
To: Julius Patrick,Greenville Utilities Commission(GUC)
Dail Booth, GUC
Jesse Chadwick,GUC
From: David Briley, P.E., Hazen and Sawyer(Hazen)
Melanie Mann,P.E.,Hazen
Sara Gibson,P.E., Hazen
Re: Solids Estimation Recommended Testing Plan
This memorandum provides an overview to the recommended sampling plan for GUC staff. Collected
results will provide confirmation of solids estimation assumptions used for the residuals management
facilities design in the Preliminary Engineering Report. The sampling plan focuses on total suspended
solids(TSS) for typical plant operation and sedimentation basin blowdown.
Typical Plant Operation
The GUC WTP currently measures"pre-settled"turbidity prior to rapid mix/flocculation/sedimentation
and"settled"turbidity after these processes. Solids estimation calculations currently utilize a factor to
convert measured turbidity to TSS.This factor has been selected based on similar project experience and
literature-based information. TSS measurements will provide guidance for a plant-specific factor in solids
estimations calculations.The sampling plan is detailed in Table 1-1 below.
Table 1-1: Typical Plant Operation Sampling Plan
Location Parameter Frequency
Turbidity Once per
Pre-Settled Week
TSS
Turbidity Once per
Settled Week
TSS
It is recommended that samples be taken during typical solids loading conditions,at consistent locations,
and at the same time. Hazen recommends that GUC carry out this sampling plan for one year to capture
seasonal variations.
Sedimentation Basin Blowdown
The solids estimations calculations assume a percent solids in sedimentation basin blowdown. It is also
assumed that similar solids loading occurs across all six basins; GUC staff have indicated that solids
loading is typically higher in Basins 1, 5,and 6.The analysis of TSS in the blowdown across several
basins will provide additional guidance for these calculations.The sampling plan is detailed in Table 1-2
below.
Hazen and Sawyer•4011 WestChase Boulevard Suite 500• Raleigh, NC 27607•919.833.7152

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Appendix D: Total Suspended Solids Sampling Plan
Hazen and Sawyer I Appendix D—Total Suspended Solids Sampling Plan D-1

Greenville Utilities Commission tS8gME
Greenville NC
Project #: 3605-15-038 3201 Spring Forest Rd.
Raleigh, NC 27616
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9 Remarks Example of build up on pipeline at the 37'mark
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10 Remarks Example of build up on pipeline at the 51'mark
note heavy build up on the entire Tee Joint and flange bolts

Greenville Utilities Commission
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Greenville NC
Project #: 3605-15-038 3201 Spring Forest Rd.
Raleigh, NC 27616
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8 Remarks Example of build up on pipeline at the 23'mark
note heavy build up in sections but not covering entire pipe

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Greenville NC
Project #: 3605-15-038 3201 Spring Forest Rd.
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Greenville Utilities Commission --_- S&ME
Greenville NC
Project #: 3605-15-038 3201 Spring Forest Rd.
Raleigh, NC 27616
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Greenville Utilities Commission S&IVIE
Greenville NC '
Project #: 3605-15-038 3201 Spring Forest Rd.
Raleigh, NC 27616
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Form No.TR-NDT-UT-02 S&M_E
Revision No.: 1 ULTRASONIC THICKNESS REPORT
Revision Date:07/23/09
Project No.: 3605-15-038 Project Name: Greenville GUC Date: 9/19/2015
Client Name: GUC Job Specification: ASME Procedure No.: WI-TP-NDT-UT-04
Location: Finsh Water Flush Material Type: Ductile Iron Surface Condition Scraped Clean
Piece No.: N/A Grid Lines: N/A Elevation: Below Floor
Geometry: Pipe Thickness: .750- .799" Diameter: 24"
Ultrasonic Flaw Detector/Gage Transducer(s) Calibration Standard(s)
Manufacturer: Panametrics Manufacturer: Panametrics Material: Ductile Step# Thickness
Model No.: DL38 Plus Model No.: D790-SM S/N: 1289 11 1 .100"
Serial No: 110194505 Serial No.: 754080 5 .500"
Cable Type: jak Straight Frequency: 5Mhz
Cable Length: 48" Size: 7.9mm
SKETCH IF REQUIRED
Thickness Readings Taking
The thickness readings were taking inbetween the T joints locaed at the 39'mark and the 143'mark.
Readings Location 0 Min 12.5 15 17.5 30 37.5 45 57.5
39' 798" .799" .797" .798" .797" .797" .796" .796"
49' 798" .797" .796" .795" .795" .794" .768" .798"
73' 796" .796" .795" .798" .796" .799" .796" .797"
120' 794" .796" .795" .797" .797" .796" .795" .798"
143' .793" .795" .797" .796" .765" .797" .799" .795"
Pitts measured at 35'mark located at 0 min mark Pitt measured: .128" depth.Pipe wall thickness.796"
Pitts measured at 35'mark located at 10 min mark Pitt measured: .126"depth.Pipe wall thickness.795"
Pitts measured at 60'mark located at 15 min mark Pitt measured: .130"depth.Pipe wall thickness.797"
Pitts measured at 75'mark located at 30 min mark Pitt measured: .125"depth.Pipe wall thickness.796"
Pitts measured at 80'mark located at 12 min mark Pitt measured: .131"depth.Pipe wall thickness.794"
Pitts measured at 85'mark located at 45 min mark Pitt measured: .130" depth. Pipe wall thickness.797"
Pitts measured at 100'mark located at 0 min mark Pitt measured: .131"depth.Pipe wall thickness.796"
The staff of GUC and the onsite engineer asked for the inspectors to scrape some of the build up off the pipe looking for
pitts and measure them.They also asked that we do not scrape any from the above the water line.They informed us that
they did not have a patch for the pipline if a leak occurred and we complied.
Please see photos of pipeline
k--
Mark Powers UT level 2 May 9,2013
Examiner's Name Level/Certification Technical Responsibility Date
Disclaimer: The presence of S&ME at the project site shall not be construed as an acceptance or approval of activities at the site. S&ME is at
the project site to perform specific services and has certain responsibilities which are limited to those specifically authorized in our agreement
with our client. In no event shall S&ME be responsible for the safety or means and methods of other parties at the project site. The
information presented in this field report has not been reviewed by an engineer and is to be considered preliminary.
Page 1 NDT Report NO. UT09192015a
P

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Appendix C: September 2015 Backwash Supply
Header Assessment Report
Hazen and Sawyer I Appendix C—September 2015 Backwash Supply Header
and Assessment Report C-1

Hazen
References
Halle,Cynthia,Huck,Peter M.,and Peldszus, Sigrid."Emerging Contaminant Removal by Biofiltration:
Temperature,Concentration,and EBCT Impacts(PDF)."Journal AWWA 107,no. 7(July 2015): E364-
79. doi:http://dx.doi.org/10.5942/jawwa.2015.107.0086.
Richter,Doreen,Gudrun Massmann,and Uwe Diinnbier. "Behaviour and Biodegradation of
Sulfonamides(P-TSA,O-TSA,BSA)during Drinking Water Treatment."Chemosphere 71,no. 8 (April
2008): 1574-81.doi:10.1016/j.chemosphere.2007.11.026.
Zearley,Thomas L.,and R. Scott Summers. "Removal of Trace Organic Micropollutants by Drinking
Water Biological Filters."Environmental Science&Technology 46,no. 17(September 4,2012): 9412-
19.doi:10.1021/es301428e.
Appendix B Page B-51

Hazen
Filter Run Times and Unit Filter Run Volumes (UFRV)
The combined results from the full-scale demonstration,the pilot,and the WRF evaluation tool suggest
that filter run times and UFRVs will decrease with biofiltration.This is expected to be worse during the
warmer summer months and improve in the winter. Decreased UFRVs will also affect the net water
production,which will have the greatest impact during the warmer summer months when the peak
demands are highest.(Section 13.4).The WRF conversion tool suggests that 50%of the existing
biofilters in the United States have run times of greater than 48 hours. Of the various chemical addition
strategies to improve UFRV,caustic addition offered the greatest improvement in UFRVs.
Chemical Addition
The pilot results suggest that either caustic or peroxide should be used to improve biofilter performance,
as caustic and peroxide demonstrated the greatest filter performance improvements.Neither phosphorus
addition nor dual chemical additional provided benefits over caustic or peroxide individually.
Capital and Operational Costs
The cost estimate for the intermediate pump station and the WRF biofilter conversion tool highlight the
additional costs that are associated with biofiltration. The intermediate pump station is expected to cost
approximately between$5,000,000 and$6,000,000.Additional biofiltration costs include the increased
operational requirements due to more frequent backwashing,chemical requirements,and increased
biofilter monitoring costs.
Recommendations
This report recommends that GUC should continue to use and expand their abiotic filtration process.This
report also recommends that the current expansion should be designed and constructed so that GUC has
the option to convert to biofiltration if treatment requirements change in the future.
Biofiltration would assist GUC in improving water stability and reducing disinfection byproducts;
however,this would come at the cost of decreased water quality,decreased filter run times,and increased
capital and operating costs. Since the water quality improvements are incremental,not substantial, and
not required to meet current regulations, it is recommended that GUC continue with abiotic filtration.
However, it is important to note,that without the impact of the capital costs,this report would
recommend biofiltration.
Of the chemical enhancement strategies,the results suggest that either caustic or peroxide can improve
UFRVs with minimal water quality impacts and both are recommended, if desired.Dual chemical
addition with either caustic or peroxide did not provide a greater operational improvement then the most
advantageous chemical alone,and hence,dual chemical addition is not recommended.
Appendix B Page B-50

Hazen
magnitude lower than the NDMA action level of 10 ng/L.The WRF biofilter conversion tool confirmed
these results and suggested that biofiltration may provide DBP precursor removals of up to 20%.
Biofiltration will not allow GUC to switch their secondary disinfectant from combined chlorine to free
chlorine,as the SDS free chlorine tests suggest that DBP concentrations in the distribution system will
exceed the Stage 2 DBPR for TTHM at the 80 µg/L MCL and HAAS at the 60 µg/L MCL with free
chlorine disinfection.
Taste and Odor Control and Emerging Contaminants
The results from the pilot and the full-scale demonstration suggest that biofiltration will improve control
of taste and odor compounds and reduce emerging contaminants.EEMS results from the pilot suggest
that biofiltration will improve removal of larger DOM,and the full-scale demonstration aldehyde results
suggests that BAF will also remove small organic molecules. Pilot results,however, suggested that
biofiltration is not expected to impact effluent UV254, as Ozone-BAF pilot UV254 removal was similar to
full-scale UV254 removal.
Manganese Removal
The combined results from the full-scale demonstration,the pilot,and the WRF evaluation tool suggest
that manganese removal will not be an issue except during high manganese events when manganese
breakthrough is a possibility. The pilot was able to meet the secondary MCL of 0.05 mg/L for
manganese,which suggests satisfactory control of manganese with biofiltration;however,the full-scale
conversion data did show manganese breakthrough during Hurricane Irene. If necessary,caustic can
improve manganese removal, as the pilot columns with caustic had average effluent manganese
concentrations of less than or equal to 0.01 mg/L.
Effluent Water Quality
Biofiltration is not expected to increase or decrease filtered water turbidity. Results from the full-scale
demonstration show comparable turbidities between the biofilter and the abiotic filters.Although the
pilot effluent turbidities where higher than expected,as the average pilot effluent turbidity ranged from
0.15 to 0.2 NTU,the average pilot turbidity values were lower than the Interim Enhanced Surface Water
Treatment Rule value of 0.3 NTU.The pilot results also suggested that different treatment conditions
would not affect the turbidity.
Biofiltration is expected to increase the bacterial concentrations in the filtered water.The pilot filter
effluent had high levels of HPC and coliform. The higher pilot effluent bacterial concentrations suggest
that the secondary disinfection system should be evaluated if full-scale Ozone-BAF is selected to ensure
sufficient microbial inactivation.The pilot results also suggest that there were no major differences in
biological activity between the different chemical conditions.
Appendix B Page B-49

Hazen
Overall
Driver Component Evaluation Method Conclusion Suitability
Overall TOC and WRF biofilter conversion Moderate suitability
AOC removal tool
HAAs and THMs Pilot analysis Reduce disinfection
byproduct formation
Disinfection NDMA special sampling, Limited concern for GUC, Moderate
byproducts NDMA pilot analysis reduces NDMA further
Switch to free Pilot analysis GUC cannot switch to free
chlorine chlorine
Manganese breakthrough
Total and during extreme
Manganese dissolved Full scale demonstration, manganese events. Moderate
removal manganese pilot analysis Caustic enhances
manganese removal
Turbidity Full scale demonstration, No impact is expected
pilot analysis
Effluent Moderate-
water quality Increased bacterial High
Biological growth Pilot analysis concentrations in biofilter
effluent
UFRV UFRV Full scale demonstration, Decreased UFRV Low
pilot analysis
Chemical Recommended Pilot analysis Caustic or peroxide Moderate
addition chemical addition
Water Stability
Biofiltration will improve water stability for GUC through TOC, DOC, and AOC removal. Results from
the pilot suggest that Ozone-BAF will remove an average of 0.75 mg/L of DOC. AOC testing yielded
inconclusive data; however,the WRF biofilter conversion tool suggests that biofiltration can remove up
to 40% of the AOC. The variable AOC data did suggest that chemical addition will have a minimal
impact on full-scale AOC removal.
Disinfection Byproducts
Biofiltration will improve DBP precursor removal when compared to abiotic filtration, and biofiltration
will lead to reduced concentrations of DBPs in the distribution system. Results from the pilot suggest that
GUC will continue to meet the Stage 2 DBPR for HAAS and TTHM with biofiltration.The pilot results
suggest that NDMA formation will not be an issue for GUC with biofiltration. SDS test NDMA levels
remained less than 2 ng/L for pilot and full-scale samples,and these levels are approximately an order of
\pp ndo 13 I'l i li-i5

Hazen
Summary of BAF Evaluation Results
Table B-9 provides summaries of the key BAF components,conclusions,and suitability rankings for
GUC's BAF drivers and concerns,respectively.Biological filtration will improve water stability for
GUC through additional total organic carbon(TOC),dissolved organic carbon(DOC),and AOC
removal.Pilot data indicated that Ozone-BAF could improve DOC removal by 20 percent.AOC removal
would likely be enhanced by 40 percent with BAF. Biofiltration would improve regulated DBP precursor
removal by nearly 50 percent.Currently,GUC staff is in compliance with the Stage 2 DBP Rule, so
enhanced DBP precursor removal is not a strong driver for converting to biological filtration.
Biofiltration alone would not provide for enough DBP reduction to support GUC switching secondary
disinfectant from combined chlorine to free chlorine. Research suggests that biological filtration would
gg g
provide an effective barrier for taste and odor compounds and emerging contaminants;however, certain
compounds are more recalcitrant to biodegradation and are unlikely to be removed through biofiltration.
GUC staff's current practices have effectively managed algae growth in the pre-sedimentation basin and
taste and odor.Emerging contaminants could become an important driver for conversion to biological
filtration.As discussed in Section 2,promulgation of new rules for emerging contaminants are not
expected in the near-term.
Manganese control was found to be a concern with biological filtration. Biological filtration was
effective for manganese removal at low levels but was not able to control high levels during water quality
excursions.Caustic addition proved to enhance manganese removal in the pilot testing. However,the
removal of pre-filter chlorine feed would require multiple manganese barriers to provide similar process
robustness as compared to current WTP operations.
Biological filters had higher levels of HPC in the effluent. In the pilot columns,coliform concentrations
were fairly low. However,the sloughing of bacteria in the biological filters does present a risk and GUC
staff should consider UV disinfection system to provide an additional barrier for pathogens.Pilot testing
and full-scale demonstration showed that filter runtimes would be lower with biological filtration by
70 percent during the summer months. Caustic and/or peroxide addition in the filter influent were
effective for enhancing UFRV.
Table B-9: Key Biological Filtration Conclusions and Suitability Rankings
Overall
Driver Component Evaluation Method Conclusion Suitability
Nitrification DS water quality Evidence for limited
potential in the analysis nitrification events
Water distribution system Moderate-
stability High
TOC / DOC Pilot analysis Improve water stability
Appendix B Page B-47

Hazen
25,000
20,000
Typical biological
UFRV
Typical Abiotic UFRV
15,000 —
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10,000
5,000 —
0
Col. 1 Col.2 Col. 3 Col.4 Col.5 Col.6 Col. 7 Col. 8
(Cont) (Phos) (pH) (Phos+pH) (Upflow) (Peroxide) (Peroxide+pH) (GUC No.6)
Figure B-31: Ozone-BAF Pilot Average Unit Filter Run Volume Results
Appendix B Page B-46

Hazen
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Figure B-30: Inorganic Material at 100x Magnification
Ozone BAF Operational Requirements
UFRV is used to compare filter hydraulic performance to normalize for filtration rate and filter surface
area.Figure B-31 illustrates the average UFRV results for the pilot study.The control pilot columns had
comparable UFRVs to the full-scale biofilter No. 6 with UFRV of approximately 6,500 gal/SF.The
upflow BAF column had the highest UFRV of over 20,000 gal/SF,as expected, since the upflow
configuration likely allowed for some minor bed expansion.Caustic and peroxide addition improved
UFRV to 12,050 gal/SF and 9,510 gal/SF,respectively.However,UFRV for the BAF pilot columns,
except for the upflow filter,was significantly less than GUC's abiotic filters(e.g., 14,500 gal/SF).
Appendix B Page B-45

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ci
Figure B-28: Biological Flocs at 1000x Magnification
4
f
M.r
• k , T.
•
•
e ! $ �• a
y a. "•' s
C.. ,gym " i ;,,x,* w.. �, x. ,
Il ..,
f: -fi,
Figure B-29: Biological Flocs with Filamentous Bacteria at 1000x Magnification
Appendix B Page B-44
I

Hazen
• ••,„,$(.,:„... t .,,,,.„ .1til.. ,......,,,,,,t4,,,,s ..... _
• .,,Ito,,,,,,,i,
0
.• ..... . ..„ ,_. .t.t.,-.. .--.4,....,
4,...,
,,,54
, ., ... . 4a,,),,../44.1,,4q-ttzt, i„....,
", �n< .. r'� - / ' ' gyp-Ite'
tok,
0.
q
• _
- 1`. '.. ` '1 !w� /t• *°'� q, i ,Rye te.
,ill .*401..\
Isco*,:ii.zt,
S ,y •
siiiit * r . n K �r • �, ,
lit
a
".,�` *14 t ,/ f.. ,* : • 4 Sad. '
0 •
Figure B-26: Biological Floc at 100x Magnification
i41
t
Figure B-27: Smaller Flocs at 100x Magnification
Appendix B Page B-43

Hazen
Although the ATP data was lower than expected,the data suggests that microbial activity was similar
between the treatment conditions and that microbial activity was similar throughout the column and not
specific to a region of the filter.
EPS Media Profiles
Media EPS data suggested similar EPS formation in all columns except column No. 5 (Figure B-25).
The upflow column had between two to three times more EPS than the downflow columns. Similarly,to
the ATP results, except for column No. 5,there was no strong relationship between EPS concentrations
and filter location.
140
120
100
o
pi 80
rn
c 60
w 40
20 II 111 III III 111 III In III
0
Filter 1 Filter 2 Fitter 3 Filler 4 Filter 5 Filter 6 Filter 7 Filter 8
■Top •Middle ■Bottom
Figure B-25: EPS Content from the October 25th Sampling Event(pg/g)
Ozone-BAF Floc Microscopy Analysis
A filter floc sample was collected October 18th for microscopy analysis of the pilot filter floc after
Hurricane Matthew. The microscopy results show that the material was mostly biological in nature
although some inorganic material was present. Small inorganic particles were also present in the settled
material. Floc size ranged from 20-500 um. Filament organisms were also present in the floc material.
Figure B-26 through Figure B-30 show the microscopy results. These results suggest that the observed
flocs in the filter columns were not carryover from the clarifiers but biological growth.
Appendix B Page B-42

Hazen
ATP Media Profiles
ATP media profiles were taken on August 30th and October 25th. The ATP values from both days were
significantly lower than expected(Figure B-23 and Figure B-24). Media ATP concentrations were lower
than 100,000 pg ATP/g media. Typical results for biological filters range between 400,000-800,000 pg
ATP/g media.
800000
700,000
600,000
500,000 ----..
rn 400,000 -
300,000 - -.
200,000 --
100,000
0 ELMiM MOM NM Mti si -psi -1•111.1 MEMO 1.111• 11'
Cd 1 Cd.2 Cd-3 Cd 4 Cd 5 Cd.6 Cd.7 Cd.8
(Copt` rPnos) (pH) (Phos+pH) (006b\,) (Peroxide) (PeroodevH) ((RUC No 6)
■Top ■Middle ■Bottom
Figure B-23: ATP Results from the August 30th Sampling Event(pg/g)
800 000
700,000
600,000
500,000
400,000
a
a
r
300,000
200,000
100,000
0 MINE ■EMI NMI NMI_ ■rras11111 ■N•. ■Ili
Cd.1 Cd.2 Cd.3 Cd.4 Cd.5 Cd 6 Cd 7 Cd 8
(Cant) (Phos) (pH) (Ph06+pH) (Wore) (Peroxide) (Peroxide.pH) (GUC No 6)
■Top ■Middle •Bottom
Figure B-24: ATP Results from the October 25th Sampling Event(pg/g)
Appendix B
pp Page B-41

Hazen
Turbidity
The typical finished water turbidity is less than 0.03 NTU. Typical pilot effluent turbidities were higher
by almost a factor of 10. The average pilot effluent turbidity ranged from 0.15 to 0.2 NTU. However,the
average pilot values were lower than the Interim Enhanced Surface Water Treatment Rule value of
0.3 NTU. Figure B-22 illustrates the average Ozone-BAF turbidity values for each column. The data
suggests that chemical addition had a minimal impact on pilot effluent turbidity, as filter effluents from
all columns converged on an average value that ranged between 0.15 to 0.2 NTU.This phenomenon is in
contrast with GUC's previous experience of feeding caustic to the filters,which was observed to
increase effluent turbidity levels.
0 400
Typical Full Scale
(0-03 NTU)
0 350
IESWTR(0.3 NTU)
0.300
Pilot Threshold(0.25 NTU)
0250
0200 _.
0.150
0.100 -
0.050
0.000 --
Cd 1 Cd 2 Cd.3 Cd 4 Cd.5 Cd 6 Cd.7 Cd.8
(Conti (PhDs) (pH) (Phos.pHi (Ho(bw) (Peroxide) (Peroxide-.pH) (GUC No 6)
Figure B-22: Average Ozone BAF-Pilot Turbidity Results
Additional Testing
Coliform and HPC testing, dissolved oxygen(DO)monitoring, and visual observations suggest that there
were no major differences in biological activity between the different chemical conditions. It should be
noted that the pilot filter effluent had high levels of HPC in the effluent. Observed levels of coliforms
were low in the pilot,and continued to improve with time over the course of the pilot. On only one
occasion was a most probable number(MPN)of greater than 200 cells/ml observed.

Hazen
0.10 0.09 —
0.08 0.07
0.06 — .
rn -
E - Secondary MCL
c
§ 0.05 —
v
a>
0 0.04 —
0
0.03 —
0.02 —
Full Scale < 0.01 mg/L
0.00
Influent Col. 1 Col.2 Col.3 Col.4 Col.5 Col.6 Col. 7 Col.8
(Cont) (Phos) (pH) (Phos+pH) (Upflow) (Peroxide) (Peroxide+pH) (GUC No.6)
Figure B-21: Average Ozone-BAF Pilot Dissolved Manganese Results
1ppendi-•: R Page B-39

Hazen
To further evaluate the impact of biofiltration on NDMA, formation potential tests were performed to
with simultaneous chlorine and ammonia addition,to reflect higher NDMA formation"risk"conditions,
in which no additional oxidation of NDMA precursors was provided by free chlorine. These results show
that GUC has a low NDMA formation potential(Figure B-20).
120
NDMAAction Level
10.0
80
a
0 60
LL
2 40
20
00 •
Break Tank Cd 1 Cd 2 Cd 3 Cd 6 Full Scale
(Conti (Phos) (pH) (Peroxide) (Filter 6)
Figure B-20: Ozone-BAF Pilot SDS Testing with Simultaneous Dosing of Chlorine and Ammonia
Manganese
The BAF pilot columns was able to meet the secondary MCL of 0.05 mg/L for manganese with
relatively low influent manganese levels(<0.05 mg/L). Caustic enhanced manganese removal to 76 to
84 percent, as compared to 20 to 45 percent for the other pilot columns. Figure B-21 provides the
average Ozone-BAF dissolved manganese concentrations for each column.
Appendix B I agc

Hazen
NDMA
Results from the SDS testing with 15 minutes of free chlorine followed by ammonia addition
demonstrate that NDMA levels remain less than 2 ng/L for the pilot and full-scale operation, as
illu
strated in Figure B-19. These levels are well below the NDMA action level of 10 ng/L, are
g ,
reflective of the observed low levels of NDMA observed over time in the GUC system.
tz0
1o.o
NDMA Action Level
80
60
2
Z 4.0
2.0
0 0 • , , , . ■ , , ■ , _ ■ ills■
° . O •L a C a ( c0 a V �.
COva Ua Ue C�= u-
• 0
a
Figure B-19: Ozone-BAF Pilot SDS Testing with 15 Minutes of Free Chlorine Contact Time
Followed by Ammonia Addition
Npi,,u,liy Is LI L I-k .�%

Hazen
Potential for Free Chlorine Distribution System Disinfection
Results from the free chlorine SDS test suggested that an Ozone-BAF process will not enable GUC to
switch to free chlorine disinfection. The SDS tests suggest that system DBP concentrations with free
chlorine may exceed the Stage 2 DBPR for TTHM at the 80 µg/L MCL and HAA5 at the 60 µg/L MCL.
Figure B-18 illustrates the free chlorine SDS HAA and THM results.
160
140 —120 .._-
100
Stage 2(TTHM)
= so
II Stage 2(HAA5) '
x 60II I
fl_li .-
Brealc Tank Co 1 Cd 2 Cd 3 Cd-6 Full Scale Full Scale
(Conti (Phos) (pH) (Peroxide) (Finer 6) (Combined)
■Total HAA ■Total THM
Figure B-18: Ozone-BAF Pilot Free Chlorine SDS HAA and THM Results
Appendix B Page B-36
4

Hazen
90 -
Stage 2 (TTHM)
80 —
70 —
Stage 2 (HAA5)
60 — .,....�..
•
J
= 50 —
40 -
30
20 lihiiIiLiI1h-i-iii
0
Col.1 Col.2 Col.3 Col.4 Col.5 Col.6 Col.7 Col.8 Full Scale Full Scale Full Scale
(Cont) (Phos) (pH) (Phos+pH) (Upflow) (Peroxide) (Peroxide+pH) (GUC No.6) (Filter 6) (Combined) (Finished)
mow Total HAA 1mm Total THM —Series3 Series4
Figure B-17: Simulated Distribution System Testing with 15 Minutes of Free Chlorine Contact Time
Appendix B Page B-35

Hazen
0.14 —
0.12
0.10
Full Scale UV254
0.08
0.06
0.04
0.02 .
0.00
Infuent Cd.1 Cd.2 Cd.3 Cd.4 Cd ca 6 Cd.7 Cd.8
(Cant) (Phos) (PH) (PhDs*pH) ',",=ide) (PercaidetpH) (GUC No.6)
Figure B-16: Average Ozone-BAF Pilot UV254 Results
Disinfection Byproducts
THMs and HAAs
Simulated Distribution System(SDS)DBP formation tests were conducted to evaluate the performance
of Ozone-BAF for DBP precursor removal.Results from the SDS testing(with 15 minutes of free
chlorine followed by ammonia addition)demonstrate that Ozone-BAF enhances DBP precursor removal
such that DBP levels were 45 to 50 percent lower than with abiotic filters.The combined filter effluent
results suggest that the combined water has the potential to exceed the Stage 2 rules for HAAS; however,
GUC staff finished water results suggest that GUC will meet the Stage 2 rules for TTHM and HAAS
(refer to Figure B-17). Results from the SDS testing with free chlorine suggests that the Ozone-BAF
process would not enhance DBP precursor removal sufficiently to enable GUC to switch to free chlorine
disinfection.
Appendix B Page B-34

Hazen
5
4.5
4
35
E 3
o —
cj 2.5
u
O
o
c 1.5
Influent Cd.t Cd.2 Cd.3 Cd.4 Cd.5 Cd.6 Cd.7 Cd.8
(Cant) (Phosi (pH) (Phos+pH) (Upfbw) (Peroxide) (Peroxide+pH) (GUC No 6)
Figure B-15: Ozone-BAF Pilot Dissolved Organic Carbon Results
UV254
Ozone-BAF pilot UV254 removal was similar to full-scale UV254 removal. Chemical addition did not
improve UV254 removal; however,the addition of caustic seemed to slightly decrease UV2s4 removal.
Figure B-16 illustrates the average Ozone-BAF UV254 for each column. The data suggests that UV254
removal using full-scale Ozone-BAF would be similar to the pilot removal rates.The exception is that
engineered biofiltration with caustic would likely result in less UV2s4 removal.
Appendix B Page B-33

Hazen
1800
1600 _ . . . . . . .
1400
1200
0 WOO
soo 1-1]- 1E
a Sv 8 ag u a n aj
�` ;t
6 U LLV
■Microbial ■Fulvic ■Humic
Figure B-14: Average Ozone-BAF Pilot EEMS Results for Microbial, Fulvic, and Humic
Components
Organics
To evaluated the impact of BAF on increasing removal of organics,pilot testing included evaluating
removal of total and dissolved organic carbon(TOC, DOC)and changes to UV absorbance(UV254),to
determine how BAF consumed or changed organics.
TOC/DOC
The Ozone-BAF pilot removed an average of 0.75 mg/L of DOC. The different columns averaged 12 to
22 percent. Figure B-15 illustrates the average Ozone-BAF DOC concentration in each column. The
pilot study results suggest that the various chemical additions tested had minimal impact on full-scale
TOC/DOC removal.None of the BAF pilot columns demonstrated improved UV2s4 removal compared
to abiotic filters. The chemical addition will have a minimal impact on full-scale TOC/DOC removal, as
no trends in TOC/DOC were observed under the different conditions.
Appendix B Page B-32

Hazen
100
80
rn
60
0
V
u
.p 40
rn
O
N
20
Influent Cd.1 Cd.2 Cd.3 Cd.4 Cd.5 Cd.6 Cd-7 Cd.8
(Cont) (Phas) (pH) (Phan*pH; (Optlow) (Peroxide) (Penmide•pH) (GUC No.6)
Figure B-13: Average Ozone-BAF Pilot Assimilable Organic Carbon Results
Excitation Emission Matrix Spectroscopy
EEMS measures the light that is absorbed and emitted from dissolved organic matter.The range of
absorbed and emitted light can be used to fingerprint and characterize the humic,fulvic,microbial
organic matter components.Figure B-14 illustrates the average EEMS results for the dissolved organic
microbial,fulvic,and humic components.The EEMS data suggests that most of the filter influent DOC
is humic and fulvic acids with a minimal microbial biopolymer component.As expected,Ozone-BAF
appears to remove a greater portion of the larger humic acids relative to the smaller fulvic acids.The
suggests that BAF will improve biological stability,as it removes the larger organic molecules the
microorganism use for growth in the distribution system.
Appendix B Page B-31

Hazen
Ozone-BAF Water Quality Impacts
The following parameters were monitored during the pilot to assess how Ozone-BAF would affect water
quality and stability:
• Stability parameters, including assimilable organic carbon(AOC), fluorescence excitation
emission matrix spectroscopy(EEMS),
• Organics, including TOC/DOC and UV254,
• DBP precursors, including THMs, HAAs, and NDMA,
• Manganese,
• Turbidity,
• Post-filter microorganisms.
Stability Parameters
To evaluate the impact of BAF on improving distribution system water stability, pilot testing included
evaluating removal of AOC and changes to fluorescence,to determine how BAF consumed or changed
bioavailable carbon created by ozonation.
AOC Testing
AOC testing yielded inconclusive data.The variable AOC data suggests that chemical addition will have
a minimal impact on full-scale AOC removal. Figure B-13 illustrates the average Ozone-BAF AOC
concentration in each column. The overlapping error bars suggest no impacts of treatment on effluent
AOC. The second AOC sample had a longer hold time of 53-hours compared to the 28-hour hold time of
the first sample. The longer hold times may have contributed to the variable data. Because of the
p
variability and inconsistent nature of the AOC data, limited information was provided by this portion of
the testing. To provide additional information, EEMS and biological growth were examined for insight
into potential performance as related to biological stability.
Appendix B Page B-30

Hazen
peroxide supplementation, increased phosphorus and pH, increased pH and peroxide supplementation,
and an upflow configuration. The remaining two columns were used as controls. Table B-7 provides an
overview of the eight columns in the pilot.
Table B-7: BAF Column Pilot Setup
Column GAC Media Effective
Number Chemical Addition and Dose Source Size Configuration
1 None (control) Henrico 1.35 mm Gravity
2 Phosphorus (0.2 mg/L as P) Henrico 1.35 mm Gravity
3 Caustic(8.9 mg/L) Henrico 1.35 mm Gravity
4 Phosphorus (0.2 mg/L as P) + Henrico 1.35 mm Gravity
Caustic (8.9 mg/L)
5 None Benton 2.0 mm Upflow
6 Peroxide (1.5 mg/L) Henrico 1.35 mm Gravity
7 Peroxide (1.5 mg/L) + Caustic Henrico 1.35 mm Gravity
(8.9 mg/L)
8 None (Control) GUC No. 6 1.39 mm Gravity
Ozonated settled water from the WTP was pumped to a break tank for distribution to the two pilot
column racks. Each column was equipped with an influent pump controlled by a variable frequency
drive(VFD). GUC staff backwashed the filters as needed and Hazen staff made weekly visits to collect
data, modify the pilot, and prepare chemical stocks. GUC laboratory staff collected weekly samples for
in-house processing. Pilot data was screened for quality control,and filter runs were excluded if the
average filter turbidity was greater than 0.25 Nephelometic turbidity unit(NTU). Table B-8 provides an
overview of the pilot timeline.
Table B-8: Ozone BAF Pilot Timeline
Date Event
May 18th Media acclimated in GACAS
May 27th Media acclimated in filter columns
June 8th GUC operator training
June 13th Chemical feeds operational
June 20th First round of sampling
June 28th Initiated chlorinated /chloraminated backwashing
September 8th Started supplemental ozone feed
September 16th Ozone stopped
September 26th Returned to single break tank
October 25th AOC and ATP Media Sampling
November 3rd Final sampling and data collection

Hazen
chloramines for residual distribution system disinfection. Because of this,any potential regulation
developing a maximum contaminant limit(MCL)on NDMA or other nitrosamines may force systems to
consider reverting back to free chlorine for residual disinfection. Data from special NDMA sampling
performed by GUC was evaluated for NDMA occurrence, as shown in Figure B-12. The data indicate
levels of NDMA are regularly below the suggested 80%of a"likely"potential future limit(without any
explicit efforts by GUC to limit formation), indicating NDMA will probably not drive a need to revert
back to residual chlorine in the distribution system.
12
Massachusetts and California Notification/Guidence Limit is 10 ng/L.These are currently the only state
regulations of NDMA and expected to guide any potential"future"national regulation.
10
8
—•—Settled
—0--Finished
--.—County Home Road r
2 r Penny Hill/Hwy 64
2
0 --. • 0- . . • A • • • 0--
5/6/2013 11/22/2013 6/10/2014 12/27/2014 7/15/2015 1/31/2016 8/18/2016 3/6/2017 9/22/2017
Figure B-12: NDMA Results from GUC Special Sampling
Distribution System Analysis Summary
Results from the distribution system analysis are summarize as follows:
• Nitrification indicators show that some level of periodic nitrification is likely occurring within
the system, at sites with more than 24-hour water age.
• Average total chlorine levels and other nitrification indicators are within acceptable levels.
• Free ammonia, HPC, and nitrite,do approach and exceed suggested action levels on occasion.
• Regulated DBPs(THMs and HAAs)are currently in compliance.
Ozone-BAF Pilot Study
The Ozone-BAF pilot was initiated to assess the impact and feasibility of BAF at the WTP. It was
operated for 21 weeks by GUC and Hazen staff from June 8, 2016 to November 3, 2016. The pilot was
equipped with eight columns to test the following six conditions: increased phosphorus, increased pH,
Ahpeinii\

Hazen
0.1 -
0.09
TTHM MCL=0.08 mg/L
0.08
0.07 80%of TTHM MCL=0.064 mg/L ---
E 0.06
a
a 0.05
c
2 0.04
r 0.03 —
0.02
IMIHIHHIII II
0.01
0 -
'LO ,LO ,y0 ,LO LO 'LO LO ,LO ,LO LO LO
'6 Od ,61 'Ld N61 �d ',>O 16 yd txO 3d
■Site 01 ■Site 02 ■Site 03 ■Site 04 ■Site 05 ■Site 06 ■Site 07 •Site 08
Figure B-10: Locational Running Annual Averages (LRAAs)for TTHM in the GUC system.
0.08
0.07
—
HAA5 MCL=0.06 mg/L
0.06
J
0.05 80%of HAA5 MCL=0.048 mg/L
a
a 0.04
c
c 0.03
a
0.02
0.01 r.
0 -
0 0 0 o o o 0,y y ti y 1, d y y I 1, 1,o- o- a o o o o- a a o-N C � ti d � 3 t ti k) '')
■Site 01 ■Site 02 r Site 03 • Site 04 ■Site 05 ■Site 06 ■Site 07 ■Site 08
Figure B-11: Locational Running Annual Averages (LRAAs)for HAA5 in the GUC system
Nitrosamines
Future regulatory drivers, particularly with respect to nitrosamines, such as NDMA, are being
considered. National observances of NDMA from the Second Unregulated Contaminant Monitoring
Rule(UCMR2) indicated that this particular contaminant is more often linked with systems using
Appendix B Page B-27

Hazen
The analysis of existing historical water quality in the distribution system indicates that some level of
nitrification is likely occurring within the system,with the probability increasing for sites with more than
24 hours of water age.Average total chlorine and monochloramine levels decrease compared to the
finished water quality as free ammonia increases, indicative of chloramine residual breakdown.Average
total chlorine at the sampling sites is above the recommended Action Levels at all water ages,but the
low range for each water age group indicates periods where residuals are lower than Action Levels 1 and
2.This is not surprising since nitrification is often a seasonal occurring problem,associated with warm
water temperatures.
Average free ammonia levels in the distribution system exceed Action Level 1 for the 49—72 hour and
73-96 hour water age groups.Ammonia Action Level 2 is exceeded at times for sites in all water age
ranges. In general,average nitrite levels are very low and do not typically exceed the Action Levels,
however at locations with water age greater than 24 hours,the high range of nitrite has been observed to
exceed both Action Levels.Monitoring of HPC is not part of routine distribution system nitrification
monitoring,but is only initiated as part of the increased monitoring program at any locations that are
beginning to exhibit signs of nitrification.The observed elevated levels of HPCs are accompanied with
flushingprotocols,designed to quicklyeliminate burgeoning nitrification events.
� g g
A decreasing trend in pH at a sampled location can also be an indicator for nitrification,although defined
Action Limits are vague and most effectively utilized when long term pH trends can be resolved.As a
first cut indicator,observations of lower pH at a sampled location as compared to that in the fmished
water can indicate possibility of nitrification.At the monitored location,both the range and average pH
compared to the finished water pH remains relatively stable throughout the distribution system.
Disinfection Byproducts (DBPs)
The disinfection byproducts analysis considered currently regulated DBPs,as well as emerging DBP
concerns, specifically related to NDMA,as both continued compliance with the Stage 2 Disinfectants
and Disinfection Byproducts Rule(DBPR),and consideration of potential future regulated DBPs are
biofiltration drivers for GUC.
Trihalomethanes(THMs)and Haloacetic Acids(HAAs)
Historically, as a chloraminating utility,GUC has not experienced difficulty in achieving Stage 2 limits
on THMs and HAA5,as shown in Figure B-10 and Figure B-11.The Locational Running Annual
Averages(LRAAs)for TTHMs and HAAS in the GUC system indicate regulated DBPs are of limited
concern unless conditions were to require a conversion to free chlorine for distribution system residual
disinfection.
Appendix B Page B-26

Hazen
Table B-6: Summary of Distribution System Water Quality
Sites with < 24 Sites with 25-48 Sites with 49-72 Sites with 73- Sites with >96
Parameter Finished Water' Hour Water Age' Hour Water Hour Water 96 Hour Water Hour Water Age'
Age Age Age
Number of Sites 1 68 63 45 3 2
Number of Samples2 1,460 796 798 600 17 14
Total Chlorine, Average 4.1 3.4 2.8 2.4 1.9 2.8
mg/L Range 2.0 - 5.1 1.0 - 4.8 1.0 - 4.8 1.0 - 4.0 0.30 - 3.2 1.2 - 3.7
Monochloramines, Average 4.0 2.9 2.2 1.7 - 2.2 I 1.8
mg/L Range 3.0 - 5.0 0.0 - 4.6 0.0 - 4.1 0.0 - 3.6 2.2 - 2.2 0.0 - 3.5
Free Ammonia, Average 0.0083 0.077 0.11 0.16 0.46 0.080
mg/L Range 0.0 - 0.20 0.0 - 0.50 0.0 - 0.55 0.0 - 0.50 0.46 - 0.46 0.0 - 0.22
Average 7.7 7.6 7.5 7.5 7.5 7.5
pH - _
Range 7.1 - 9.0 7.0 - 8.8 7.0 - 8.0 I 7.0 - 7.9 7.0 - 7.8 7.4 - 7.8
Average N/A 164 319 507 243 441;
HPC (R2A) _ ___ _. _- _
Range N/A 1.0 - 3300 1.0 - 464111_ 1.0 - 7200 4.0 - t-931 9.0 - 4240
Average N/A 0.0055 0.0069 0.0068 0.026 0.0067
Nitrite-N, mg/L
Range N/A 0.0010 - 0.038 0.00 - 0.34 0.00 - 0.32 0.0020 - 0.20 0.0030 - 0.014
Average 420 481 473 464 452 502
ORP, mV
Range 268 I - 523 189 - 733 196 - 842 172 - 704 277 - 556 367 - 600
Orthophosphate, Average 1.1 1.1 1.1 1.1 1.0 1.1
mg/L Range 0.81 - 1.4 , 0.81 - 3.1 0.80 - 2.2 0.84 - 1.3 0.86 - 1.3 0.92 - 1.2
'January 2011 through December 2014;finished water conductivity and ORP are typical values from lab daily analysis log sheets.
'Total number of dates that samples were taken.Some parameters not sampled every date.
;1ppcxii,' N Page B-25

Hazen
system.Additionally,GUC monitors locations on a rotatingbasis,with very few sites
overall distributiony y,
overlapping on a regular basis,making"trending"of data difficult.It is recommended that GUC develop
a nitrification monitoring and action plan,to enact as part of ongoing distribution system monitoring, in
order to develop a robust dataset from which to draw more definitive distribution system stability
conclusions moving forward.
Appendix B Page B-24

Hazen
Nitrate
Chloramine Residual
Total Ammonia
0
R
Free
Ammonia
HP
Time
Figure B-9: Changes in nitrification water quality parameters during an event
In addition to these water quality factors, several physical/operational parameters including water age and
pipe condition are also important. Some of these factors, such as water temperature are beyond the control
of utilities.However,regular maintenance and cleaning efforts of distribution infrastructure,as well as
controlling water age,will help reduce the potential for nitrification.
Action levels for response to distribution system results indicating potential nitrification must be
developed specifically for each utility.Experience-based action levels are developed after operating a
chloraminated system,with rigorous monitoring of water quality parameters and trending.As a first cut
for this evaluation,preliminary Action Levels are presented in Table B-5,based on American Water
Works Association(AWWA)guidelines,as well as those used by other North Carolina utilities using
chloramines.
Table B-5: Preliminary Action Levels for Nitrification Indicators
Parameter Action Level 1 Action Level 2
• Total Chlorine(mg/L) 1.2- 1.5 < 1.2
Free Ammonia(mg/L) > 0.15 >0.20
Nitrite-N (mg/L) 0.02 -0.05 > 0.05
HPC (CFU/mL) > 100 > 200
pH* "Slight" drop in pH compared to >0,5 pH unit drop in pH
finished compared to finished
Key Distribution System water quality parameters related to nitrification in the GUC system are
summarized in Table B-6,organized as the GUC WTP finished water and for sites of varying water ages
within the distribution system. Water ages for each site address were estimated based on distribution
system modeling.Although a large amount of data was analyzed,the ability to draw concrete conclusions
about occurrences of nitrification in the distribution system was limited by a few factors. Specifically,
GUC has only 5 sampling locations with more than 72 hours of water age(out of a total of 181 locations).
As high water age is often a major contributing factor to nitrification, it is recommended that GUC locate
and monitor more locations with high water age to provide a more comprehensive representation of the
Appendix B Page B-23

Hazen
Summary
The following results from the BAF demonstration project were utilized for the evaluation.
• BAF provides removal of aldehydes, a surrogate for bioavailable carbon, suggesting potential
improvements to biological stability of finished water.
• BAF provides for similar effluent turbidity as conventional filtration,providing an indication
that BAF can be utilized as effectively as conventional filtration as the primary pathogen
physical barrier at GUC.
• BAF provides adequate manganese control under typical manganese conditions. However,
when manganese levels were elevated, conventional filtration was able to ensure low
manganese levels,while biofiltration was unable to perform adequately.
• Seasonal decreases in filter run times and UFRVs were observed when compared to traditional
filtration, with filter run times reducing to a minimum of less than 20 hours in 2011.
Distribution System Evaluation
Historical finished water quality and distribution system water quality were assessed, focusing on
nitrification events and DBP formation to provide context for the driver or need to improve distribution
system water quality(e.g., both bio-stability and disinfection byproducts).
Distribution System Evaluation
The potential for nitrification is a primary concern for water systems using chloramines.Nitrification can
lead to a rapid depletion of chloramine residuals, which may subsequently lead to bacterial growth in the
distribution system and possible non-compliance with coliform limits. Total chlorine, monochloramine,
free ammonia,total ammonia, pH, nitrite, nitrate,and HPC are common parameters monitored for
nitrification by other water utilities. In addition to these water quality factors, several physical/operational
parameters including water age and pipe condition are also important.
Water quality data in the GUC system was evaluated to assess historical occurrence of nitrification. Total
chlorine, monochloramine,free ammonia,total ammonia, pH, nitrite,nitrate, and heterotrophic plate
counts(HPC)are common parameters monitored for nitrification by other water utilities. Figure B-9
provides a schematic of typical patterns observed in these water quality parameters as a nitrification event
progresses at a particular location.
Page B-22

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20,000
Average Filter 1 Average Filter 6
UFRV(Abiotic) UFRV(BAF)
18,000
16,000
•
14,000
12,000
10,000
fy 8,000
u •
6,000 - -
IT
4,000 - -
2,000 - -
0 -
N6 OHO F.6 1\6 ONO N6 P\O N6 N6 N6 N6 N6 OHO N6 \O ,\6 ONO i\O N6
�°h.p, 0.12, 0�.41, 6�'L41, 41, 1��61, '��'�41, 1��bp, '�"��\� \\� ��'�0, 0�41, O41, o��0, 0��41, °��,\41, O�'l �O\�'L �psdl,
■Filter 6(BAF) •Filter 1 (abiotic)
Figure B-8: Full Scale UFRV for Filter No. 1 (Abiotic) and Filter No. 6 (BAF)
Appendk f3 Page 13-21

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In December of 2015, filter No. 6 run times decreased to below 20 hours. Filter surveillance was
conducted and found the GAC media condition had deteriorated significantly. As a result,the GAC
media was replaced with 12-inches of sand and 48-inches of Norit GAC 816 in March 2016. During the
summer of 2016, unit filter run volume(UFRV)was monitored and compared with Filter No. 1 (refer to
Figure B-8). UFRVs for filter No. 6(BAF) increased after the media change-out, suggesting that media
condition was a factor in previously observed short run times. During the summer of 2016,the average
UFRV for the BAF filter(6,800 gal/SF)was 53 percent less than the average UFRV (14,360 gal/SF)for
an abiotic filter. Even with new media, BAF performance resulted in seasonal reductions in filter run-
time.
•
Appendix B Page B-20

Hazen
0 Filter 1 (Conventional) o Filter 6 (BAC)
120 - . ,
100 o T
_
o .-b o ®d -i o o . a :� o 0 0 0 4
° ° q
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F 80 - o d§) 0- a a ® 0
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40 A-4---Q-,o ---g ,
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00
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0 I 0 1 1 1 1 I
8/10/2010 2/26/2011 9/14/2011 4/1/2012 10/18/2012 5/6/2013 11/22/2013 6/10/2014
Figure B-7: Filter Run Times Observed in Full-Scale BAF Demonstration
Ali-midi'. 1; Page B-19

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Post-filter Microbial Quality
The filters at the GUC WTP are relied upon heavily for turbidity removal, serving as the primary
physical barrier to particles(and pathogens,by extension)in the finished water.Elevated post-filtered
turbidity can also indicate excessive"sloughing"of microorganisms from BAF.To evaluate post-filtered
turbidity,GUC data analysis was performed by plotting daily average turbidities from Filter No. 1
(conventional)and Filter No. 6(biological)from 2010 to 2014,to compare BAF with abiotic filters
during water quality excursions.These data suggest that multiple manganese barriers would be needed
with BAF(Figure B-6).Another concern of BAF is the potential for elevated levels of microorganisms
in the BAF effluent from filter biogrowth"sloughing".
0.30
.
0.25 - —_�.
1
S
0.20 •• ' 4 .• j
t • .
. ,
k :14. ..
0 R y s .
0) 4 si'itIlir .%,; F.I.:Q.L.t !VI,.'c .., ,„•
0. ei
05 • sic • A..
8/10/2010 2/26/2011 9/14/2011 4/1/2012 10/18/2012 5/6/2013 11/22/2013 6/10/2014
• Filter 1 (Conventional) Filter 6(BAC)
Figure B-6: Average Daily Turbidity from 2010 to 2014
Filter Hydraulics
Filter hydraulics were evaluated using data from the full-scale BAF demonstration study,along with
additional updating with GUC data analysis.Abiotic filters at the WTP typically achieve 96-hour filter
run times.The full-scale BAF observed seasonal reductions in filter runtimes to as low as 20 hours(refer
to Figure B-7). Shorter filter run times may impact net water production of the WTP.To exacerbate the
situation, seasonal reduction in run time occurs in the summer,when higher system demands are
experienced.Other regional utilities have also observed significant impacts to capacity, observing 1
summer time BAF"bottlenecks,"which have reduced firm capacity to less than half of design capacity.
Appendix B Page B-I8
1

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1.40 -
1.20 -
1.00
13)
J -
0.80
N
(n
a
C _
fV
m 0.60 -
2
To
_ Secondary MCL
0.40 fill
0.20r
_- Iu
''‘ 4111 41416461,
o.00 -�
0 4191 (O \rO 40 19 O rO eO rO O t 4rP O 46) ,LO \‘P
—Filter 1 Filter 4 —Filter 6 -- CMB Filter —Raw Mn —Series6
Figure B-5: Total Manganese from Biological Filters from October 2010 to February 2012
AT-wench'. I; Page B-17

Hazen
filter. During Hurricane Irene, raw water manganese levels increased up to 1.3 mg/L. During this period,
the biofiltration experienced manganese breakthrough with 16 days of levels exceeding the SMCL.This
demonstrates the risk of BAF in that it is not as robust for manganese control as compared to abiotic
filters during water quality excursions. These data suggest that multiple manganese barriers would be
needed with BAF.
Appendix B Page B-16

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to remove CECs,as research has demonstrated biofiltration's ability to improve CEC removal over
conventional water treatment processes(Halle, et al.2015;Zearley and Summers,2012;and Richter,et
al.2008).
Although biofiltration has shown promise as a process for CEC removal,research gaps exist and the
research suggests variable CEC removal performance with biofiltration.Work by Zearley and Summers,
(2012)has shown that some CECs are resistant to biodegradation and thus are not removed with
biofiltration,as 13 of 34 compounds studied had no removal through biofilters.This research also
demonstrated four removal trends for biofiltration,which included consistent removal over the year
(ibuprofen), increasing removal and stabilization(molinate and 2,4-D),decreasing removal
(trimethoprim),and no removal(atrazine)(Figure B-4).
100 Ibuprofen
Molinate
ou
410(
60
CO
0
E 40 �-- 2,4—D Trimethoprim
as p .
cc
20
citet
Atrazine
0 �►
0 100 200 300 400
Micropollutant Exposure (days)
Figure B-4: CEC Removal Trends for Biofiltration (Adapted from Zearley and Summers, 2012)
Halle,et al.(2015)demonstrated that temperature affects the performance of CEC removal through
biofiltration,with greater reductions at higher temperatures.This suggests that CEC removal is expected
to vary over the course of the year as the average water temperatures change.
Future work is needed to better understand why certain compounds are not effected by biofiltration and
what methods can be used to predict and improve biofilter removal of CECs. WRF project 4559—The
Simultaneous Removal of Multiple Chemical Contaminants Using Biofiltration—seeks to address these
gaps and is expected to be released later in 2017.
BAF Considerations
Effluent Manganese Concentrations
Figure B-5 details the historical raw and biologically filtered manganese levels from October 2010 to
February 2012.Historically,the biofilters demonstrated decent manganese control with levels typically
consecutive below the secondary MCL although levels did average 0.02 mg/L higher than in the abiotic
Appendix B Page B-15

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Taste and Odor
Recently,utilities have begun to employ the combination of ozone and biofiltration,or even biofiltration
alone,as a strategy to reduce MIB,geosmin,and other T&O compounds.In this process,ozonation
typically achieves 30%to 75%removal of MIB and 40%to 60%removal of geosmin at typical ozone
doses. Biofilters operating downstream of ozonation typically achieve greater than 80%removal of the
remaining MIB and geosmin, often removing raw water concentration to below detection levels.
In a recent pilot study for a Central Virginia facility,biological filtration with 7.5-minute empty bed
contact time(EBCT)and fresh GAC were evaluated for removal of taste and odor.Upstream treatment
included only conventional treatment and chlorine dioxide oxidation,which was not effective in
reducing MIB and geosmin.Results from this study are shown in Figure B-3 and clearly indicate that,
while GAC was capable of consistently removing MIB and geosmin to below detection,BAF was
capable of removing 50%to 75%of MIB and geosmin. Interestingly,after a brief acclimation period,
BAF performance greatly improved,as shown by the steadily increasing removal of both MIB and
geosmin by BAF over the 2-week testing period. While ultimate removal is reasonably efficient with
biofiltration,the length of time required for the acclimation period indicates some risk of T&O
breakthrough with BAF,particularly without upstream ozone treatment.
100% 100%
>90%* >90%* >90%*
90% - 90%
80% - 3.5% 80% >75%* >75%* >75%*-71/0
o
r r 69%
_70% 1111 j 70%
58.5% ��
0 60% — y 60%
cc 50% 11111 c 50%
m v 40% -
40%
30%
20% 20% -
10% I 10%
0% 0%
2-day 1-week 2-weeks 2-day 1-week 2-weeks
■Fresh Carbon ■Biofilter e Fresh Carbon 0 Biofilter
Figure B-3: Removal of MIB and geosmin at Central Virginia 8-minute EBCT Biofiltration Pilot.*
denotes removal to the detection limit.
Emerging Contaminants
Contaminants of emerging concern(CEC)define a group of compounds that are not routinely monitored
in the environment and cause or are suspected of causing adverse health effects.CECs include personal
care products(PCPs),endocrine disrupting compounds(EDCs),volatile organic compounds,
cyanotoxins,pesticides, and pharmaceuticals.Biofiltration is attracting attention as an emerging method
Appendix B Page B-I4

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90
80
70
60 ----
-en _
E 50 —
vi
a) -
r 40 —
a)
- -
30
20 — - - - --
10
0 — M_PIM_ r
PIM
Conventional Filter BAF with Anthracite BAF with GAC Media Post Contactor
Media
Figure B-2: Aldehyde Levels in Filter Effluent
Appendix B Page B-I3

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Literature and Data Review
Using a literature review,along with a review of the data from the 2010—2012 full-scale BAF
demonstration projectl, and additional evaluation of GUC data, impacts of BAF on several identified
drivers and considerations for BAF were evaluated, including:
• Drivers
o Biological Stability(BAF demonstration)
o Taste and Odor(Literature review and similar project data)
o Emerging Contaminants(Literature review)
• Considerations
o Manganese(BAF demonstration)
o Post-filter microbial quality(GUC data evaluation)
o Filter run time(BAF demonstration, GUC data evaluation)
Background k round on BAF Demonstration
Beginning in 2010, GUC initiated a full-scale demonstration of BAF by converting Filters No. 4 and 6 to
biofilters. The chlorine feed to full-scale Filters No 4 and 6 were stopped in October 2010 to evaluate the
performance of BAF on anthracite media(Filter No. 4)and GAC media(Filter No 6). Filter No. 1 with
sand/anthracite and pre-filter chlorine feed was used a control. Effluent manganese concentrations,
effluent aldehyde concentrations, effluent turbidity, and filter run times were evaluated for Filters No. 1,
No. 4, and No. 6.Updates and extended analysis were performed during the course of this evaluation,
specifically to address several additional water quality concerns and bolster initial findings from the
demonstration study.
Impact of BAF on Treatment Drivers
Biological Stability— BAF Consumption of Aldehydes
Aldehydes are simple organic molecules that are used as a proxy for biodegradable organic matter
removal. In the full-scale testing, GUC evaluated removal of aldehydes across conventional abiotic
filters, as well as in two biofilters(anthracite and GAC media).The results suggest that BAF provides
improved aldehyde removal, effectively reducing post-filter aldehydes by nearly 90 percent(refer to
Figure B-2). While not a direct correlation with AOC,the data indicates that biofiltration would be
capable of removing AOC and improving biological stability significantly.
I Treatment and Water Quality Improvements Evaluation, Draft Technical Memorandum#5. HDR,
October 24,2012
Alm(!kiiy 13 Page B-12

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Summary of WRF Biofilter Conversion Assessment Tool
The following bullets summarize the results of the biofilter conversion assessment tool.
• The Water Research Foundation(WRF)Biofilter Conversion Assessment Tool was
successfully used to evaluate the suitability of Ozone-BAF for GUC,relying upon GUC staff
supplied operations data and performance goals.
• The model suggests that a conversion to BAF is moderately suitable for GUC, with the
highest rated categories including"design"and"operations"
o Design rating relied heavily upon GUC's 8 minute EBCT for supporting biological
growth.
o Operations rating relied heavily upstream ozone for supporting generation of AOC.
• The model neglected to consider several key concerns of GUC, including
o Operational complexity associated with shortened filter run times.
o Capital cost associated with intermediate pumping or more filters for addressing
hydraulic capacity concerns.
• Water quality performance metrics suggested as feasible by the tool were mixed, including
o Expected improvement in finished water quality stability.
o Expected less than 40%AOC reduction.
o Expected less than 20%reduction in DBP precursors.
o Caustic likely necessary to meet low manganese levels.
o Expected increases in operating costs associated with chemical feed and more frequent
backwashes.
•
Appendix B Page B-1 1

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Category Suitability Component Consideration
Chlorinated Backwash Survey suggests that backwashing with chlorine has no detrimental
effect on GAC biofiltration at doses of up to 2 mg/L.
GUC Sampling The analytical lab at GUC can sample for a suite of parameters that
characterize biofiltration.
Operational Moderate-High The upstream processes at GUC are typical for facilities with
Information Upstream Processes biofiltration; however, excessive upstream phosphorus removal
may increase biofilter fouling.
Ozone BAF is suitable following ozone to removal AOC.
Piloting GUC has conducted a short-term pilot (6 months) and understands
how biofiltration is expected to perform over summer months.
Other Key Moderate Staff Familiarity and Training The staff is familiar with biofiltration and additional training could be
Factors provided.
Biofilter Conversion Plan A biofilter conversion plan would assist the facility in switching to
biofiltration.
Appendix B Page B-I0

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Table B-4: Summary of Water Research Foundation Biofilter Conversion Assessment Tool Results
Category Suitability Component Consideration
Nutrient Levels (N and P) Tool suggests that the nutrients present in the biofilter influent at
and Assimilable Organic GUC are sufficient for biofiltration. Nutrient levels observed during
Carbon (AOC) the pilot and pilot observations suggest that nutrient
supplementation is unnecessary.
Water Quality Moderate Annual Source Water Warmer average annual water temperatures at GUC support
Temperature biofilm growth.
River water is a common water source for facilities with biofiltration.
Water Source In the biofiltration knowledgebase, 32% of the facilities with
biofiltration have a river water source(WRF 4459).
TOC Removal Tool suggests that facilities should expect less than 20% removal.
AOC Removal Tool suggests that facilities should expect less than 40% removal.
DBP Precursor Removal Tool suggests that facilities should expect less than 20% removal.
Biofiltration knowledgebase suggests that more than 50% of the
Filter Run Times facilities with biofiltration have average run times of greater than
48 hours. Detailed information on unit filter run volumes was not
Performance provided.
Goals Moderate Tool suggests that caustic supplementation may be necessary to
Manganese Removal meet low manganese levels and suggests a long-term pilot to
confirm manganese removal over changing water quality
conditions.
Tool suggests that operational costs may increase with biofiltration
Operational Costs because of shorter filter run times, chemical requirements, and
monitoring requirements.
Finished Water Stability Biofiltration is expected to improve finished water stability.
Empty Bed Contact Time GUC EBCT is 8 min at the design filter loading rate of 4 gpm/SF.
Design Moderate-High (EBCT) This provides sufficient time for contaminant removal. A higher
EBCT will increase contaminant removal.
Appendix B Page B-9

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Model Output
The WRF biofiltration tool suggests that Ozone-BAF is a moderately suitable alternative for GUC;
however,converting to biological filtration would improve some water quality parameters at the expense
of compromised operations.Figure B-1 provides an illustration of the WRF Biofilter Conversion
Assessment Tool results,and Table B-4 provides an overview of the results from the assessment tool and
highlights key components and considerations.
Overall Suitability for Conversion to Biofiltration
2 Moderate- - - ---
Q
rn Low
Water Quality Desigr. Performance Goals Operational Information Other Key Factor=
CATEGORY
Figure B-1: Summary of the Overall Suitability for Conversion to BAF, as characterized by the
WRF Biofilter Conversion Assessment Tool
Of note in the results are the modest predictions for water quality improvement,with less than 20%
reductions expected in TOC and DBP precursors. In addition,while less than 40%reduction in AOC
across BAF would likely lead to increased biostability in the distribution system,the magnitude of that
improvement is questionable.In addition,the tool suggests evaluating caustic addition for improving
manganese removal across BAF.This strategy was tested further in the pilot program.
Design and Operational Information ranked highest in"suitability"for GUC,based mainly on the fact
that GUC has an 8 minute EBCT,which is adequate for supporting biological degradation of
contaminants,and upstream ozone,which will assist in generating AOC. The tool also indicated that
50%of utilities implementing BAF observe greater than 48 hour run times.This would represent a 50%
reduction in run time compared to current abiotic operation,and historical data indicates potential for
even shorter run times.Reductions in hydraulic capacity from BAF at GUC indicate the need for capital
improvements,either in the form of additional filter capacity(N+1+1)or intermediate pumping to
increase filtration capacity or driving head,respectively.Factoring in this required capital expense and
operational complexity would reduce the"suitability"of the design and operational factors at GUC to
moderate or moderate low, if the factors were included in the evaluation.
Appendix B Page B-8

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Table B-3: Summary of WRF Biofilter Conversion Assessment Tool Model Input
Water Quality Design Criteria Performance Goals Operation Information Other Key Factors
Coag./Floc., Organic TOC/DOC
Water River Upstream Clarification, TOC 10-20% parameters (grab), Level of Short-term
Source Processes Pre-oxidation Removal that will be UV254(grab) Evaluation pilot
(Ozone) measured
Biological Target
Average 3.0-6.0 Design 5-10 minutes AOC >40% Parameters DO uptake, Duration 3-6 months
TOC mg/L EBCT Removal that will be HPC, EPS for Biofilter
measured Acclimation
Will biofilter Written
Filter TTHM and be taken
> 15 deg Biofilter Biofilter
Influent C Media G/S HAA5 FP < 20% down for No Conversion No
Temp Removal longer than Plan?
one week?
Mn Control,
Emerging Training on Both
Filter Contaminants, biofilter monitoring
Influent Additional Operational Cost monitoring
C:Ratio < 10:1 Chlorine No Benefits Reduction, T&O N/A N/A and and
Residual Control, Process operational operational
Stability, Finished training training
Water Biostability
Will SOP
Above Backwash Lowest and data
Influent with Yes Acceptable analysis
detection >48 hours N/A N/A Not Known
Ortho-P limit Chlorine (Continuous) Filter Run guidance
Residual Time be
provided?
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• Operational Information—e.g.,expected acclimation period, planned monitoring parameters
and frequency
• — evaluations, operation training
KeyFactors e.g., planned
P
The operations data and performance goals entered into the tool were based on the previously
ascertained data and conversations with GUC staff. This data included typical water quality data,filter
design characteristics, performance goals, operational capabilities, and other expected goals. Data input
into the tool are summarized in Table B-3.
1l,hcn�li� I I'a,Lk fi-(,

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been monitored in the abiotic(chlorinated)filter effluent.However,this concern was evaluated by
analyzing turbidity from the full-scale data analysis and from the pilot,comparing the heterotrophic plate
counts(HPC)and coliform counts between the full-scale abiotic filters,full scale BAF,and the pilot
biofilters. In addition,extra polymeric substances(EPS),adenosine triphosphate(ATP),and dissolved
oxygen(DO)were quantified to compare the biology between the pilot filters.Results from the WRF
biofilter conversion tool pertaining to water quality performance goals were also taken into
consideration.
Filter Run Times
GUC is concerned with biofiltration's impact on facility operations regarding shorter filter run times.To
evaluate this concern,the operational data from the full-scale demonstration and the pilot was compared
to the full-scale abiotic filter operation.Results from the WRF biofilter conversion tool pertaining to
filter run times were also taken into consideration. Finally,unit filter run volumes(UFRVs)were used in
lieu of filter run times,as the UFRV accounts for the filter loading rate and surface area,which are not
accounted for in run time calculations.
Chemical Addition
The chemical requirements of biofiltration is a concern for GUC.Previous work has shown that chemical
addition enhanced biofiltration performance,and that chemical addition may be required for satisfactory
performance.To evaluate this concern for GUC,the pilot was operated with the following conditions:
pH adjustment,phosphorus addition,phosphorus addition with pH adjustment,peroxide addition,
peroxide addition with pH adjustment,and upflow operation with a larger media.
Water Research Foundation Biofilter Conversion Assessment Tool
The Water Research Foundation(WRF)Biofilter Conversion Assessment Tool was used to evaluate the
suitability of Ozone-BAF for GUC.This tool was developed as part of WRF Project No.4496,and
released in early March,2017. The Biofilter Conversion Assessment Tool was designed to provide
utilities an evaluation of the relative feasibility of conversion to biofiltration by evaluating the suitability
of specific facilities for conversion to biofiltration and providing tailored mitigation strategies.
Assumptions and Model Inputs
Required inputs to the WRF Biofilter Conversion Assessment Tool evaluates relative suitability and
mitigation strategies based upon user inputs from the following five key categories:
• Water Quality—e.g., influent turbidity,pH,temperature,organics,nutrients
• Performance Goals-e.g.,desired run time, intended benefit of biofiltration
• Design Criteria—e.g.,empty bed contact time,media type,media depth,upstream chemicals
Appendix B Page B-5

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BAF Considerations
As part of a holistic BAF evaluation,the following concerns should be evaluated: reduced manganese
removal, decreased effluent water quality, increased filter run times, chemical requirements for
optimized BAF implementation, and increased capital and operational costs associated with BAF
compared to currently utilized abiotic filtration. Table B-2 summarizes the considerations and expected
impacts to GUC.
Table B-2: Considerations for BAF Adoption at GUC
Considerations Expected Impact Importance at GUC
High manganese levels can Typically low manganese in raw water,
Manganese removal ! overwhelm BAF and result in but manganese excursions occur
manganese breakthrough. occasionally. Multiple treatment barriers
would be required.
Filter effluent Possible increase in effluent Filtration is primary barrier for
microbial quality bacteria levels. pathogens.
Filter run times and Increased fouling leads to Important to net water production and
unit filter run volumes shorter filter run times (24 to reliable capacity.
(UFRV) 1 40 hours).
Chemical addition may be Caustic and peroxide addition enhanced
Chemical addition needed to optimize biofilter UFRVs.
performance.
Capital and Higher costs to provide deeper BAF requires additional hydraulic head
operational costs filters, canopy, and potentially to optimize UFRV.
intermediate pumping.
Manganese Removal
The potential for manganese breakthrough with biofiltration is a concern for GUC.GUC has satisfactory
manganese removal through oxidation/filtration, and extreme manganese events can overwhelm
biofilters. To evaluate this concern, a finished water quality assessment was conducted,the results from
the WRF biofilter conversion tool were taken into consideration, manganese results from the full-scale
demonstration were evaluated, and dissolved and total manganese were monitored during the BAF pilot.
Filter Effluent Microbial Quality
The filters at the GUC WTP are relied upon heavily for turbidity removal, serving as the primary
physical barrier to particles in the finished water. Turbidity is a proxy for microorganism breakthrough
or sloughing from a filter,with a concern being potential for elevated levels of microorganisms in the
BAF effluent, leading some utilities to implement advanced UV treatment post-BAF to ensure an
additional disinfection barrier. Historically, indicator organisms such as HPCs and coliforms have not
Appendix B Page B-4

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biostability, information from the WRF biofilter conversion tool,the literature and data review, and the
BAF pilot were evaluated.
Disinfection Byproducts
Continued compliance with the Stage 2 Disinfectants and Disinfection Byproducts Rule(DBPR)is a
biofiltration driver for GUC.Historically,as a chloraminating utility,GUC has not experienced
difficulty in achieving Stage 2 limits on TTHMs and HAAS. Future regulatory drivers,particularly with
respect to nitrosamines, such as NDMA,are being considered.National observances of NDMA from the
Second Unregulated Contaminant Monitoring Rule(UCMR2) indicated that this particular contaminant
is more often linked with systems using chloramines for residual distribution system disinfection.
Because of this, any potential regulation developing a maximum contaminant limit(MCL)on NDMA or
other nitrosamines may force systems to consider reverting back to free chlorine for residual
disinfection.To further evaluate DBPs as a water quality driver,removal of regulated DBP precursors
was evaluated during the biofiltration pilot,with samples from the pilot and full-scale filters.The results
from the WRF biofilter conversion tool were also taken into consideration.In addition,reductions in
DBP formation under a theoretical"free chlorine"disinfection scenario was also evaluated, for GUC to
consider the ability to use free chlorine as a secondary disinfectant in the future.Finally,presence of
NDMA precursors and removal with BAF was evaluated through the pilot effort.
Taste and Odor Control and Emerging Contaminants
Improving the water's aesthetic quality and ensuring costumer protection from emerging contaminants,
such as pharmaceuticals and pesticides is a driver for GUC. The presence of objectionable tastes and
odor(T&O)compounds in surface water supplies is a growing problem facing drinking water utilities
across the U.S.Two of the most common surface water T&O compounds, MIB and geosmin,are
metabolites of blue-green algae(cyanobacteria).MIG and geosmin have an earthy/musty T&O that can
be detected by human senses at concentrations of 10 ng/L,or even lower.Utilities across the country
have employed the combination of ozone and BAF as a strategy to reduce MIB, geosmin, and other
T&O compounds.The impact of BAF on T&O will be evaluated in literature and data review.
Emerging Contaminants
Regulation of emerging contaminants(i.e.pesticides,pharmaceuticals, personal-care-products,and
endocrine disruptors)is not on the immediate horizon,however utilities should begin to better
understand the presence and removal of emerging contaminants from their drinking water supplies.
Ozone-BAF effectively removes some trace organic compounds.Generally, ozone alone oxidizes
compounds containing amine groups,phenolic groups,and unsaturated carbon structures. Further
degradation of ozone created byproducts and other trace organic contaminants may be achieved with
BAF. Consideration of the impact of BAF on emerging contaminants will be evaluated in literature and
data review.
Appendix B Page B-3

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This section is organized as an evaluation of drivers and challenges to BAF implementation at GUC.
Through meetings with GUC staff and literature review, a series of benefits and challenges have been
identified by Hazen. Drivers and challenges will be contextualized and addressed for GUC in subsequent
sections, relying upon historical data collected during the BAF evaluation effort.
Drivers for Biofiltration
Table B-1 summarizes the drivers for BAF at GUC, providing information on expected magnitude of the
driver. As part of a holistic BAF evaluation,water quality and operational considerations associated with
implementation of BAF were evaluated.
Table B-1: Drivers for BAF Adoption at GUC
Driver Expected Impact j Importance at GUC
BAF improves water stability in the Likely important to reduce nitrification
Water stability distribution system through removal of
AOC generated via ozone. potential in high water age areas.
Up to 20% removal of dissolved Not important under current
Disinfection organic matter(DOM)and reduction in I'I chloramination. Important if residual free
byproducts DBP precursors (mostly HAA
precursors). chlorine desired in the future.
Reduced nuisance odor compounds Algae based taste and odor not
Taste and odor such as MIB and geosmin by up to historically observed. However, odor
control 50% complaints occur when ozone not in
I service.
Limited and variable removal of EDCs Not currently regulated, and limited
Emerging and PPCPs without ozone (effective evidence of their presence. However,
contaminants when coupled with ozone). Tar River is impacted by agriculture and
Perfluorinated compounds not well I urban runoff, along with WWTP point
removed. sources.
Water Stability
The formation of assimilable organic carbon(AOC)generated during ozone oxidation of organic matter
has been shown to contribute to water stability challenges in finished water. In treatment processes
implementing ozone treatment, BAF is often utilized remove AOC in an effort improve water stability.
AOC is a difficult and expensive analysis to perform, and is therefore not a regularly monitored
parameter in water treatment. However,distribution system instability can manifest itself through a
variety of symptoms, including difficulty to maintain chlorine residual, regular and repeated nitrification
events, and in extreme cases, even corrosion and/or red water events. To contextualize the magnitude of
the water stability driver at GUC (given current operations of ozone followed by conventional(abiotic)
filtration), a distribution system water quality analysis was performed, focusing on maintenance of
chlorine residual and presence of nitrification indicators. To understand the impact of BAF on
Appendix B Page B-2

Hazen Memorandum
To: Greenville Utilities Commission
From: Hazen and Sawyer
Appendix B: Biological Filtration Analysis
Introduction
BAF is defined as filtration through a granular media bed without the maintenance of a disinfectant
residual across the bed,resulting in a fixed-film,biologically active filter.There has been an increased
interest in implementing BAF throughout the United States due to its ability to improve water quality,
water stability,and DBP removal.BAF is often implemented after ozone treatment in particular,to
reduce the concentration of bioavailable organics produced during ozonation and to control biological
(re)growth in the distribution system.
Many of the potential benefits,as well as challenges related to implementing BAF, are site-specific and
rooted in the water quality of a particular water system.Therefore, it is prudent to consider a holistic
evaluation of the costs and benefits of BAF. To assist GUC in evaluating whether BAF represents a
viable and cost effective option to meet the desired water quality benefits,a multiple-step BAF analysis
was performed. In support of this holistic evaluation of BAF for GUC,Hazen performed the following.
• Identified BAF drivers and considerations for implementation.
• Evaluated the WRF BAF conversion evaluation tool(WRF 4496),and analysis of the results
of the full-scale BAF demonstration.
• Performed literature and water quality data reviews to consider BAF impacts on biological
stability,taste and odor,emerging contaminants,manganese,post-filter microbial quality, and
filter hydraulics,
• Performed a distribution system evaluation to contextualize the disinfection byproduct drivers
and distribution system stability.
• Performed an Ozone-BAF pilot study to understand the impact of BAF operational strategies
on water quality and hydraulics.
BAF Process Drivers and Considerations
While BAF can improve water quality,particularly post-ozone,by further reducing organics and
improving water quality, implementation of BAF has also been linked to operational and water quality
• challenges, including reduced filter run times,turbidity breakthrough, increased levels of indicator
• organisms(defined by HPC and total coliforms(TC))in the BAF effluent,and mixed performance for
management of manganese. Some of these challenges may be addressed by design and operational
strategies,but it is important to identify and contextualize important drivers and challenges in order to
evaluate the feasibility of BAF for GUC.
Hazen and Sawyer•498 Seventh Avenue, 11th Floor• New York, NY 10018•212.539.7000

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Appendix B: Biological Aerated Filtration Literature
pp g
Review and Detailed Water Quality
Analysis
Hazen and Sawyer Appendix B- Biological Aerated Filtration Literature Review
and Detailed Water Quality Analysis B-1
I �

Identification Description Year Installed Material Diameter Roughness
7812 C-factor Test#37 1959 CIP 6 123
113305 C-factor Test#37 1959 CIP 6 123
113304 C-factor Test#37 1959 CIP 6 123
113205 C-factor Test#38 0 CIP 8 30
113204 C-factor Test#38 0 CIP 8 30
7397 C-factor Test#39 1954 CIP 6 83
7398 C-factor Test#39 1954 CIP 6 83
7394 C-factor Test#39 1954 CIP 6 83
7584 C-factor Test#39 1954 CIP 6 83
7487 C-factor Test#40 1954 CIP 6 30
7482 C-factor Test#40 1954 CIP 6 30
1

Identification Description Year Installed Material Diameter Roughness
16413 C-factor Test#31 1959 CIP 6 30
114107 C-factor Test#31 0 CIP 6 30
107552 C-factor Test#31 1959 CIP 6 30
114108 C-factor Test#31 0 CIP 6 30
116079 C-factor Test#31 0 CIP 6 30
16440 C-factor Test#31 1959 CIP 6 30
116080 C-factor Test#31 0 CIP 6 30
114084 C-factor Test#32 1961 CIP 12 60
201458 C-factor Test#32 1961 CIP 12 60
201457 C-factor Test#32 1961 CIP 12 60
16520 C-factor Test#32 1961 CIP 12 60
201464 C-factor Test#32 1961 CIP 12 60
16091 C-factor Test#33 1959 CIP 6 136
15268 C-factor Test#34 1966 CIP 6 30
15186 C-factor Test#34 1966 CIP 6 30
15267 C-factor Test#34 1966 CIP 6 30
26130 C-factor Test#35 1962 CIP 6 142
26247 C-factor Test#35 1964 CIP 6 142
25906 C-factor Test#35 1964 CIP 6 142
26055 C-factor Test#35 1962 CIP 6 142
17884 C-factor Test#36 1964 CIP 6 30
26002 C-factor Test#36 1962 CIP 6 30
26033 C-factor Test#36 1962 CIP 6 30
26003 C-factor Test#36 1962 CIP 6 30
1 17907 C-factor Test#36 1964 CIP 6 30
7787 C-factor Test#37 1959 CIP 6 123

Identification Description Year Installed Material Diameter Roughness
114221 C-factor Test#28 1917 CIP 6 38
116087 C-factor Test#28 1917 CIP 6 38
116088 C-factor Test#28 1917 CIP 6 38
176540 C-factor Test#28 1917 CIP 6 38
111181 C-factor Test#28 1917 CIP 6 38
176538 C-factor Test#28 1917 CIP 6 38
176539 C-factor Test#28 1917 CIP 6 38
111182 C-factor Test#28 1917 CIP 6 38
18952 C-factor Test#28 1917 CIP 6 38
18798 C-factor Test#28 1917 CIP 6 38
112433 C-factor Test#28 1917 CIP 6 38
176537 C-factor Test#28 1917 CIP 6 38
112434 C-factor Test#28 1917 CIP 6 38
19136 C-factor Test#29 1917 CIP 6 40
19221 C-factor Test#29 1917 CIP 6 40
112563 C-factor Test#30 1917 CIP 6 30
114219 C-factor Test#30 1917 CIP 6 30
114218 C-factor Test#30 1917 CIP 6 30
114220 C-factor Test#30 1917 CIP 6 30
114212 C-factor Test#30 1938 CIP 6 30
281683 C-factor Test#30 1938 CIP 6 30
18797 C-factor Test#30 1938 CIP 6 30
16610 C-factor Test#31 0 CIP 6 30
16426 C-factor Test#31 1959 CIP 6 30
16621 C-factor Test#31 0 CIP 6 30
16427 C-factor Test#31 1959 CIP 6 30

Identification Description Year Installed Material Diameter Roughness
116007 C-factor Test#24 1960 CIP 6 140
18573 C-factor Test#25 1949 CIP 6 51
18578 C-factor Test#25 1949 CIP 6 51
112562 C-factor Test#25 1957 CIP 6 51
18632 C-factor Test#25 1957 CIP 6 51
18570 C-factor Test#25 1949 CIP 6 51
112561 C-factor Test#25 1957 CIP 6 51
18928 C-factor Test#26 1949 CIP 8 45
18942 C-factor Test#26 1949 CIP 8 45
18991 C-factor Test#26 1949 CIP 8 45
P-11872 C-factor Test#26 1949 CIP 8 45
P-11906 C-factor Test#26 1949 CIP 8 45
P-11908 C-factor Test#26 1949 CIP 8 45
114071 C-factor Test#27 1953 CIP 6 84
114072 C-factor Test#27 1953 CIP 6 84
19225 C-factor Test#28 1917 CIP 6 38
19335 C-factor Test#28 1917 CIP 6 38
18977 C-factor Test#28 1917 CIP 6 38
18755 C-factor Test#28 1917 CIP 6 38
18756 C-factor Test#28 1917 CIP 6 38
18806 C-factor Test#28 1917 CIP 6 38
18903 C-factor Test#28 1917 CIP 6 38
18897 C-factor Test#28 1917 CIP 6 38
114222 C-factor Test#28 1917 CIP 6 38
107561 C-factor Test#28 1917 CIP 6 38
111630 C-factor Test#28 1917 CIP 6 38

Identification Description Year Installed Material Diameter Roughness
28895 C-factor Test#19 1949 CIP 6 40
22792 C-factor Test#20 1949 CIP 6 40
22908 C-factor Test#20 1951 CIP 6 40
22844 C-factor Test#20 1949 CIP 6 40
22460 C-factor Test#21 0 CIP 6 124
114857 C-factor Test#21 0 CIP 6 124
22613 C-factor Test#21 0 CIP 6 124
28275 C-factor Test#22 1954 CIP 6 131
28328 C-factor Test#22 1954 CIP 6 131
28254 C-factor Test#22 1954 CIP 6 131
28276 C-factor Test#22 1954 CIP 6 131
115209 C-factor Test#22 1954 CIP 6 131
115224 C-factor Test#22 1954 CIP 6 131
115210 C-factor Test#22 1954 CIP 6 131
115223 C-factor Test#22 1954 CIP 6 131
28329 C-factor Test#22 1954 CIP 6 131
28253 C-factor Test#22 1954 CIP 6 131
28097 C-factor Test#23 0 CIP 6 80
28098 C-factor Test#23 0 CIP 6 80
1 28096 C-factor Test#23 0 CIP 6 80
28145 C-factor Test#23 0 CIP 6 80
28175 C-factor Test#23 0 CIP 6 80
28125 C-factor Test#24 1960 CIP 6 140
28168 C-factor Test#24 1960 CIP 6 140
28124 C-factor Test#24 1960 CIP 6 140
116008 C-factor Test#24 1960 CIP 6 140

Identification Description Year Installed Material Diameter Roughness
114392 C-factor Test#16 1917 CIP 6 70
25398 C-factor Test#16 1917 CIP 6 70
20495 C-factor Test#16 1917 CIP 6 70
20291 C-factor Test#16 1917 CIP 6 70
114391 C-factor Test#16 1917 CIP 6 70
115317 C-factor Test#16 1917 CIP 6 70
115318 C-factor Test#16 1917 CIP 6 70
P-11842 C-factor Test#16 1917 CIP 6 70
20408 C-factor Test#17 1917 CIP 6 111
20407 C-factor Test#17 1917 CIP 6 111
28954 C-factor Test#17 1917 CIP 6 111
176138 C-factor Test#17 1917 CIP 6 111
28917 C-factor Test#17 1917 CIP 6 111
4685 C-factor Test#18 1963 CIP 6 147
4687 C-factor Test#18 1963 CIP 6 147
28878 C-factor Test#18 1963 CIP 6 147
115298 C-factor Test#18 1963 CIP 6 147
28897 C-factor Test#18 1963 CIP 6 147
P-11902 C-factor Test#18 1963 CIP 6 147
P-11904 C-factor Test#18 1963 CIP 6 147
28800 C-factor Test#19 1940 CIP 6 40
115306 C-factor Test#19 1940 CIP 6 40
115305 C-factor Test#19 1940 CIP 6 40
115304 C-factor Test#19 1940 CIP 6 40
114878 C-factor Test#19 1949 CIP 6 40
114877 C-factor Test#19 1949 CIP 6 40

r
Identification Description Year Installed Material Diameter Roughness
18880 C-factor Test#12 1917 CIP 6 40
19372 C-factor Test#12 1917 CIP 6 40
19371 C-factor Test#12 1917 CIP 4 40
19368 C-factor Test#12 1917 CIP 8 40
19370 C-factor Test#12 1917 CIP 4 40
18929 C-factor Test#12 1917 CIP 6 40
19392 C-factor Test#12 1917 CIP 6 40
19369 C-factor Test#12 1917 CIP 6 40 1
109647 C-factor Test#13 1947 CIP 6 42
109646 C-factor Test#13 1947 CIP 6 42
109644 C-factor Test#13 1947 CIP 6 42
28870 C-factor Test#14 1935 CIP 6 48
28664 C-factor Test#14 1935 CIP 6 48
28687 C-factor Test#14 1935 CIP 6 48
115280 C-factor Test#14 1935 CIP 6 48
25395 C-factor Test#14 1914 CIP 6 48
28937 C-factor Test#14 1935 CIP 6 48
28692 C-factor Test#14 1935 CIP 6 48
28959 C-factor Test#14 1935 CIP 6 48
28962 C-factor Test#14 1935 CIP 6 48
P-11770 C-factor Test#14 1935 CIP 6 48
P-11772 C-factor Test#14 1935 CIP 6 48
28650 C-factor Test#15 1938 CIP 6 40
28820 C-factor Test#15 1938 CIP 6 40
28946 C-factor Test#15 1938 CIP 6 40
20166 C-factor Test#16 1917 CIP 6 70

Identification Description Year Installed Material Diameter Roughness
20666 C-factor Test#06 1967 CIP 8 30
20765 C-factor Test#07 1905 CIP 8 60
20774 C-factor Test#07 1905 CIP 8 60
116128 C-factor Test#07 1905 CIP 8 60
P-10338 C-factor Test#07 1905 CIP 8 60
P-10340 C-factor Test#07 1905 CIP 8 60
P-11954 C-factor Test#07 1905 CIP 8 60
20059 C-factor Test#08 1905 CIP 6 120
20057 C-factor Test#08 1917 CIP 6 120
20471 C-factor Test#08 1905 CIP 6 120
P-12536 C-factor Test#08 1905 CIP 6 120
114425 C-factor Test#08 1905 CIP 6 120
114426 C-factor Test#08 1905 CIP 6 120
19683 C-factor Test#08 1917 CIP 6 120
20058 C-factor Test#08 1905 CIP 6 120
20470 C-factor Test#08 1917 CIP 6 120
P-11870 C-factor Test#08 1917 CIP 6 120
20469 C-factor Test#09 1917 CIP 6 40
20467 C-factor Test#09 1905 CIP 6 40
20084 C-factor Test#09 1905 CIP 6 40
20112 C-factor Test#10 0 CIP 6 40
20417 C-factor Test#10 0 CIP 6 40
20421 C-factor Test#10 0 CIP 6 40
114256 C-factor Test#11 1917 CIP 6 142
114255 C-factor Test#11 1917 CIP 6 142
19228 C-factor Test#11 1917 CIP 6 142

Identification Description Year Installed Material Diameter Roughness
19484 C-factor Test#03 1917 CIP 6 138
19679 C-factor Test#03 1917 CIP 6 138
P-12524 C-factor Test#03 1917 CIP 6 138
19477 C-factor Test#03 1917 CIP 6 138
19260 C-factor Test#04 1917 CIP 6 40
19407 C-factor Test#04 1917 CIP 6 40
19256 C-factor Test#04 1917 CIP 6 40
19259 C-factor Test#04 1917 CIP 6 40
19278 C-factor Test#04 1917 CIP 6 40
19279 C-factor Test#04 1917 CIP 6 40
264060 C-factor Test#04 1917 CIP 6 40
19358 C-factor Test#04 1917 CIP 6 40
19359 C-factor Test#04 1917 CIP 6 40
P-12034 C-factor Test#04 1917 CIP 6 40
16476 C-factor Test#05 0 CIP 6 142
114097 C-factor Test#05 0 CIP 6 142
114098 C-factor Test#05 0 CIP 6 142
20545 C-factor Test#06 1967 CIP 8 30
20604 C-factor Test#06 1967 CIP 8 30
20601 C-factor Test#06 1967 CIP 8 30
20602 C-factor Test#06 1967 CIP 8 30
20600 C-factor Test#06 1967 CIP 8 30
20603 C-factor Test#06 1967 CIP 8 30
20631 C-factor Test#06 1967 CIP 8 30
20544 C-factor Test#06 1967 CIP 8 30
20667 C-factor Test#06 1967 CIP 8 30
1

Updated C-Factor Field Data, Summer 2015
Identification Description Year Installed Material Diameter Roughness
19675 C-factor Test#01 1928 CIP 6 40
19446 C-factor Test#01 1928 CIP 6 40
19566 C-factor Test#01 1928 CIP 6 40
19671 C-factor Test#01 1928 CIP 6 40
19565 C-factor Test#01 1928 CIP 6 40
116123 C-factor Test#01 1928 CIP 6 40
116124 C-factor Test#01 1928 CIP 6 40
P-10102 C-factor Test#01 1928 CIP 6 40
P-10118 C-factor Test#01 1928 CIP 6 40
P-10120 C-factor Test#01 1928 CIP 6 40
19614 C-factor Test#02 1927 CIP 6 40
19584 C-factor Test#02 1927 CIP 6 40
114291 C-factor Test#02 1905 CIP 6 40
114293 C-factor Test#02 1905 CIP 6 40
114294 C-factor Test#02 1905 CIP 6 40
19589 C-factor Test#02 1905 CIP 6 40
19615 C-factor Test#02 1927 CIP 6 40
124403 C-factor Test#02 1927 CIP 6 40
19588 C-factor Test#02 1905 CIP 6 40
19573 C-factor Test#02 1927 CIP 6 40
P-10186 C-factor Test#02 1927 CIP 6 40
P-10188 C-factor Test#02 1927 CIP 6 40
P-12012 C-factor Test#02 1927 CIP 6 40
19479 C-factor Test#03 1917 CIP 6 138
19478 C-factor Test#03 1917 CIP 6 138

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Appendix A: Updated C-Factor Field Data, Summer
2015
Hazen and Sawyer I Appendix A—Updated C-Factor Field Data, Summer 2015 A-1

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
20. References
ARCADIS. October 2008. Environmental Assessment for Greenville Utilities Commission Interbasin
Transfer.
Black and Veatch. April 2009. Wastewater System Master Plan for Greenville Utilities Commission.
Black and Veatch. 2001. Water Distribution System Master Plan for Greenville Utilities Commission.
City of Greenville. September 2016. Horizons 2026: Greenville's Community Plan. City of Greenville,
Clarion Associates, and Planning NEXT.
East Carolina University. ECU Enrollment Data: 2000—2009.
Greenville Utilities Commission, Finance Department. Water Customer Account Data: 2000—2015.
Greenville Utilities Commission. Finished Water Treatment Plant Production Data: 1998—2015.
Greenville Utilities Commission. Utility Billing Data: 2000—2015.
Greenville Utilities Commission. 1997, 2002, and 2007—2015. Local Water Supply Plans. Prepared by
Greenville Utilities for North Carolina Division of Water Resources.
Groundwater Management Associates. February 2008. Engineer's Report and Supporting Data for
Construction of Water Supply Wells ASR1 and TW1.
Hazen and Sawyer. August 2013. Water Distribution System Master Plan for Greenville Utilities
Commission, North Carolina.
HDR. 2013. Greenville Utilities Commission Water Treatment Plant Facilities Master Plan.
North Carolina Department of Environment and Natural Resources Division of Water Quality. 2008.
Greenville Utilities Commission Local Water Supply Plan.
Pitometer Associates. 1961 and 1980. Greenville Utilities Water Distribution System Master Plan.
U.S. Census Bureau. City of Greenville and Pitt County Population Data: 1900, 1910, 1920, 1930, 1940,
1950, 1960, 1970, 1980, 1990, 2000, 2010, and 2015.
Vickers, Amy. 2001. Handbook of Water Use and Conservation: Homes, Landscapes, Businesses,
Industries, Farms, First Edition.
Hazen and Sawyer I References 20-1

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
The schedule for permitting and construction is currently based on the traditional approach for these
activities, where permitting is completed before major construction activities begin. Alternative delivery
projects in North Carolina to date have not followed a progressive approach in which an Authorization to
Construct(ATC) is granted based on design submittals less than 100 percent complete. However, there
may be opportunities to phase the permitting submittals so that construction activities for portions of the
project may start sooner than shown in Figure 19-2.
For the near-term distribution system improvements, planning, routing studies, design, and easement
acquisition is expected to begin in January 2018 and require up to 2 years to complete. Project bidding
would occur in early 2020 with construction beginning in mid 2020. It is expected that construction for all
the proposed 2020 improvements may be completed by mid 2022.
2017 2018 2019 2020 2021 2022
PianningmDesign(Easements
• 0
Distribution $3 sr.' Bt1011(11,
Improvements Construct ion
• •
$26.OM
Design/
MP
WTP S36MM Permitting
Improvements Construction
• •
$44.OM
Figure 19-2: Implementation Schedule for Near-Term GUC Water System Improvements
Hazen and Sawyer I Capital Improvements Program and Schedule 19-9

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 19-3: Cost Opinions for Recommended Water Distribution System Improvements
Diameter, Length,
Year Phase Recommendations inches feet Project Cost
2040 36-inch transmission main along W 5th Street 36 21,100 $10,204,000
Arlington Blvd
24-inch transmission main along NC-11 24 12,100 $3,901,000
12-inch transmission main along various 12 43,000 $5,032,000
extensions
New 2 MG elevated water storage tank -- -- $6,500,000
2040 Subtotal $25,637,000
2050 20-inch transmission main along extension 20 2,850 $766,000
16-inch transmission main along Dickinson to 16 11,100 $1,732,000
new tank
16-inch transmission main along various 16 15100 $2,356,000
Extension
12-inch transmission main along various 12 26200 $3,066,000
extensions- South
12-inch transmission main along various 12 34100 $3,991,000
extensions—North
2050 Subtotal $11,911,000
19.3 Implementation
Water demand forecasts demonstrate a potential deficit in finished water capacity in the near-term.
Therefore, implementation of the Phase 1 WTP Upgrades improvements should proceed as expeditiously
as possible. An implementation schedule has been developed based on beginning planning and design by
September 2017.
GUC is planning to implement the 32 mgd expansion of the WTP via an alternate delivery method using
the Construction Manager at Risk (CMAR) approach. Therefore, it is recommended that GUC staff proceed
with selection of the CMAR contractor so they are on board and participating near the beginning of final
design. The schedule illustrated in Figure 19-2 demonstrates that final design is expected to require
12 months to prepare 90 percent design by October 2018. Preparation and agreement of the Guaranteed
Maximum Price (GMP)would occur near the end of final design. Once the GMP and design scope is
finalized, permitting submittals would be issued to regulatory agencies. Permitting activities are planned for
4 to 6 months. Construction is anticipated to begin by 2nd quarter 2019 and require at least 24 months to
complete. Based on this schedule, the upgraded WTP would be completed by 15t quarter 2021.
Hazen and Sawyer I Capital Improvements Program and Schedule 19-8

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 19-3: Cost Opinions for Recommended Water Distribution System Improvements
Diameter, Length,
Year Phase Recommendations inches feet Project Cost
2020 48-inch transmission main from high service 48 950 $610,000
pump station to Old River Road
30-inch transmission main along Highway 33 30 24,500 $9,870,000
and Alternate 264 across River
24-inch along E 10th/ Portertown Road/E 24 21,100 $6,800,000
Firetower Road
30-inch transmission main along E Firetower 30 2,700 $1,090,000
Road
24-inch transmission main along E Firetower 24 2,200 $710,000
Road
20-inch transmission main along E Firetower 20 10,300 $2,770,000
Road
16-inch transmission main along 14th Street 16 7,400 $1,155,000
New 2 MG elevated water storage tank — — $6,500,000
2020 Subtotal $29,505,000
2025 20-inch transmission main along W Firetower 20 11,400 $3,060,000
Road
12-inch transmission main along Northern loop 12 18,300 $2,142,000
Connection
2025 Subtotal $5,202,000
2030 36-inch transmission main along Old River 36 16,200 $7,834,000
Road/264 Bypass
24-inch transmission main along Frog Level 24 3,700 $1,193,000
Road
20-inch transmission main along Frog Level
Road 20 4,350 $1,169,000
12-inch transmission main along Hwy 13 N of 12 2,400 $281,000
WTP
12-inch transmission main along Frog Level 12 3,050 $357,000
Road
2030 Subtotal $10,834,000
Hazen and Sawyer I Capital Improvements Program and Schedule 19-7

Preliminary Engineering Report
ineerin Re ort
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 19-2: Cost Opinion for Phase 1 WTP Improvements to 32 mgd
Facility Cost
Raw water pumping and transmission $3,359,000
Existing sedimentation basins $553,000
Vertical rapid mix $1,175,000
SuperPulsators $2,098,000
Ozone $55,000
Filtration $3,674,000
New clearwell pump station $1,473,000
Ground storage $3,013,000
High service pumping $340,000
Chemicals $4,745,000
Residuals $663,000
Architectural $493,000
Electrical $3,450,000
Controls $575,000
Subtotal $25,666,000
Contingencies (30%) $7,700,000
Contractor overhead and profit(15%) $5,005,000
General conditions (7%) $2,336,000
Bonds and insurance (2%) $667,000
Total Construction Cost $41,374,000
Engineering and design (15%) $6,206,000
Project Total $47,580,000
Hazen and Sawyer Capital Improvements Program and Schedule 19-6

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
19.2 Opinion of Probable Construction Cost
Opinions of probable construction costs have been developed for the recommended improvements to the
WTP and the distribution system. The cost opinion reflects total project cost including construction,
engineering and design, and contingencies. The opinions of probable construction costs are in 2017 dollars
and include the following markups:
• 30 percent for contingencies
• 15 percent for contractor overhead and profit
• 7 percent for contractor general conditions
• 2 percent for bonds and insurance
• 15 percent for engineering and design
A summary of the opinion of probable construction cost for the Phase 1 WTP Upgrades to 32 mgd and the
recommended improvements to the GUC water distribution system are provided in Tables 19-2 and 19-3,
respectively. The total cost opinion for the Phase 1 WTP Upgrades to 32 mgd is $47.6 million.
The recommended improvements to the water distribution system are phased in 5-year increments from
2020 to 2030 and then 10-year increments to 2050. The total cost opinion for improvements recommended
for implementation by 2020 are $29.5 million. These improvements are needed to address current storage
deficits, provide sufficient transmission capacity to ensure firm finished water pumping capacity meets
expected demands, and make certain system pressures remain in an acceptable range to avoid pipe
failures. An additional $5.2 million in transmission main improvements are recommended by 2025.
Hazen and Sawyer I Capital Improvements Program and Schedule 19-5

rI
Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission 1
la Greenville WASH�NG,'TON Legend
► utilities
N y Existing Tank
- it
O Prop.2020 Tank
® Prop.2040 Tank
n lif i Treatment Plant
; Proposed Pipe
i
Installed 2020
Installed 2025
Installed 2030
6 Installed 2040
Installed 2050
,.., Existing Pipe
11 <12"
LLZ op 12"-16"
NG '''• ,., „G r_18"_24•
' A aaaa=p>24'
yid 9N.�` v S.tA,1ON
Ai
tU P
"lifil'ili
Q� Water Plant w ..
- �C1O'7V
w t s _
CD
US 264 --Y n Sr h]yp� '."',TENTH si-
-4.:. 4-i:
1 � 3
}' �c
iz,:k 1s,,.,,,-0,...0,.:_CD.,-,_.c..,,..4,2.-'1..7,,
�, 4 w , cti� �s�� � 3
-y s.+ s ly. Eastside Tank
Westside Tank G" !, ` -
Southside Tank
(.;* ? c; r/ „ . 'a.Southeast Tank
O
MAIN
0 1 2 z -�
imie Miles °
U
Figure 19-1: Proposed Future Transmission and Distribution Mains, by Year of Installation
Hazen and Sawyer I Capital Improvements Program and Schedule 19-4
1

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 19-1: Recommended WTP Improvements for the Capacity Increments
Process WTP Capacity of 32 mgd WTP Capacity of 38 mgd WTP Capacity of 45 mgd
Raw Water Pump Station • Piping and wet well upgrades in raw water pump station(suction and discharge) • Four new 14 mgd pumps replacing raw water • Upsize raw water pump station suction piping
• Impeller retrofit for raw water pump Nos.2,3,4 and motor upgrades to pump pumps Nos.1,2,3,4 from intake screens
Nos.2 and 4 • Four new 16 mgd pumps replacing raw water
• New parallel raw water transmission piping/pre-sedimentation impoundment pump Nos.1,2,3,4
bypass to new rapid mix(30-inch)
Pre-Sedimentation Impoundment • Raise outlet structure elevation • No additional upgrades required I • No o additional upgrades required
-- — i nalu q �-
Raw Water Contactor • 56,000 gal raw water contactor for new train(permanganate contact) • No additional upgrades required • Additional 28,000 allon contactor
Coagulation and Sedimentation • New rapid mix with two 25 HP mixers in parallel • Additional 10 mgd SuperPulsator • Additional 10 mgd SuperPulsator
• New 10 mgd SuperPulsator • Install one 25 HP vertical rapid mixer
• Install finger weirs in existing sedimentation basins
• 48-inch yard piping to new rapid mix and existing raw water contactor
Ozone • Replace gas flowmeters(GOX meters) • Increase influent piping to 42-inch • Additional ozone contactors
• Add ozone residual monitoring to off-gas • Replace and upsize ozone generators
Filters • Four new single cell filters • Two additional single cell filters • Two additional single cell filters
• Install canopy over fitters
_ • New backwash supply header located in filter gallery -
Clearwell Pump Station • New clearwell pump station with two pumps and a slot for a third • 15 mgd of supplemental firm pumping capacity • 22 mgd of supplemental firm pumping capacity in
• New transmission piping from filter gallery to new dearwell pump station and in the new clearwell pump station the new dearwell pump station;add a third pump
from dearwell pump station to ground storage tanks
Ground Storage • New 3 MG clearwell with inset-C baffling i • No additional upgrades required i • New 3 MG dearwell with inset-C baffling
• Install baffles in existing clearwells
High Service Pump Station • Impeller retrofit and motor upgrade for finished water pump No.3 • Replace finished water pump No.2 with new • Replace finished water pump No.3 with new
• Install vortex suppression on existing pumps 18 mgd pump 18 mgd pump
• Implement suction piping improvements
Chemical Systems • Bulk chemical storage building for alum,caustic,orthophosphate,and • Additional bulk storage for alum,caustic,and • Additional bulk storage for alum and hypochlorite
dechlorination hypochlorite • Upsize day tanks in new rapid mix chemical feed
• Pre-chemical facility for SuperPulsator train and fluoride
• Upgrade fluoride bulk tank and containment • Upgrade metering pumps
• Additional/upgrade metering pumps
Residuals Management Facilities • New 16-in piping from SuperPulsator blowdown • No additional upgrades required • No additional upgrades required
• Additional outfall in northeast corner of lagoon
_ • Access road to lagoon for dredgfg/disposal operations
Architectural • Operations building office and lab modifications • No additional upgrades required • No additional upgrades required
• HVAC upgrades to existin_g filter gallery and existing hypochlorite bulk storage
Electrical and l&C • Provide new electrical power distribution to support new facilities • Provide new electrical power distribution to • Provide new electrical power distribution to
• Add a MV primary loop to power new facilities support new facilities support new facilities
• Add automatic transfer switch to add redundancy for clearwell pump power • Upgrade raw water pump station electrical • Evaluate existing generator capacity to determine
supply power distribution if upgrades are required
• Add a tie section to MV-MCC-1 and MV-MCC-2 to add redundancy
• Add a 4,h electrical utility transformer to the plant to provide required capacity
• New PLCs to support new facilities
Hazen and Sawyer I Capital Improvements Program and Schedule 19-3

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
projected in the southeastern portion of the City. Therefore, transmission capacity on the eastern side of
the City is a priority. This is further driven by the lack of transmission capacity in the eastern and
southeastern portion of the system. New transmission mains are proposed along the eastern side of the
system to tie in the new Southeast Tank into the system and ensure proper distribution system
performance and balancing of tank operation.
The recommended approach is to install a new transmission main around the eastern portion of the system
from the WTP to the proposed Southeast Tank and to the existing Eastside Tank by 2020. A 20-inch
proposed transmission main heading southwest from the Southeast Tank helps to balance that tank with
the Southside Tank and increases supply to the southwestern portion of the system. This proposed
approach establishes a nearly complete transmission loop around the system providing reliability and
flexibility in the system.
In future years, a new transmission main would be routed around the western side of the system.A 36-inch
transmission main heading west from the WTP and then south across the Tar River parallel to
U.S. Hwy 264 Bypass is proposed for installation by 2030. This main will parallel an existing 24-inch main
crossing the river. The proposed main will increase transmission capacity across the river, and provide
more supply to the western side of the city, keeping that side of the city hydraulically balanced with the
eastern side. Proposed 2040 improvements include a 36-inch transmission main extending the 36-inch
main added in 2030 to connect to the eastern loop to complete a full loop of new transmission mains
around the GUC system.A 2 MG Westside elevated storage tank is also proposed for 2040 to provide
storage for the southwestern portion of the system, which is far from other tanks and is expected to
experience substantial demand growth in the future.
Hazen and Sawyer I Capital Improvements Program and Schedule 19-2

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
19. Capital Improvements Program and Schedule
19.1 Summary of Recommended Improvements
Growth and development in the GUC service area is expected to drive an increase in water demands even
with anticipated further reductions in per capita water use due to water conservation and greater
efficiencies. GUC staff has recently observed maximum day demands of nearly 17.6 mgd. While rated for
22.3 mgd, the firm capacity of the existing WTP is 19.2 mgd based on firm filtration capacity. The firm
capacity of the clearwell pump station is approximately 17 mgd. Weather patterns in recent years have
been favorable for maintaining lower water use, however, data does not support this trend can be relied
upon. Predictions of water use and growth patterns suggest that maximum day demands could exceed
WTP capacity by 2018, earlier than the capacity expansion is anticipated to be available. Therefore, there
is a need to take actions in the near term to expand water treatment capacity as well as distribution system
capacity to accommodate current and anticipated water demands.
Hazen and Sawyer assisted GUC staff with development of a PER for the Phase 1 WTP Upgrades.
Alternatives were evaluated to expand water treatment and distribution system capacity to meet GUC's
needs through 2050. A phased plan to implement recommended improvements to the water system
infrastructure was developed to logically upgrade capacity to meet growing needs. Based on the projected
needs through 2050 and an evaluation of feasible capacity increments, recommended improvements to the
WTP were developed for the capacity expansion increments of 32, 38, and 45 mgd.
Based on the water demand projections in Section 3, an expansion to 32 mgd is expected to meet GUC's
system needs through 2035. Major WTP capacity upgrades should be planned on a 15 to 20 year horizon
to ensure adequate capacity is available to meet customer demands and to limit the frequency of large
capital projects. Therefore, an expansion to 32 mgd is recommended for the Phase 1 WTP Upgrade
project. Maximum water demands reach 38 mgd by 2043 and 45 mgd by nearly 2050. GUC should
evaluate water use trends in the future to confirm if the next capacity increment should be 38 or 45 mgd.
Table 19-1 summarizes the recommended improvements to the WTP for the capacity expansion
increments of 32, 38, and 45 mgd. Many of the WTP facilities have not been upgraded since the original
construction of the 12 mgd WTP. Therefore, most facilities at the WTP require upgrades to expand WTP
capacity to 32 mgd. The ozone system is the only major process component that has adequate capacity to
accommodate an expansion to 32 mgd.
Recommended improvements to the GUC water distribution system have been phased so transmission
and storage capacity upgrades accommodate projected demand increases. Figure 19-1 summarizes the
recommended improvements to the GUC distribution system. Currently, GUC is experiencing a deficit in
the recommended finished water storage to meet peak demands and fire flow needs. A new 2 MG
elevated storage tank is proposed in the southeast portion of the system by 2020, where much of the new
growth and development is anticipated. The 2013 Water Distribution System Master Plan recommended
an additional transmission across the Tar River to be on the western side of the City. However, anticipated
wholesale flows to Farmville have decreased since that plan was developed and significant growth is now
Hazen and Sawyer Capital Improvements Program and Schedule 19-1

Table 18-7: Design Criteria for Outdoor Conditions
Description ASHRAE Handbook(°F) Recommended (°F)
Winter
Design Dry Bulb 18 18
Summer
Design Dry Bulb 93 93
Design Wet Bulb 79 79
18.4.7 Codes and Standards
The HVAC and plumbing systems will be in accordance with the North Carolina Building Codes, ASHRAE,
and other applicable local codes and ordinances.
Hazen and Sawyer I Support Systems 18-28

18.4 Heating, Ventilation, and Cooling
18.4.1 New Chemical Bulk Storage Building
Heating, ventilation, and cooling (HVAC)will be provided throughout this building. Heating will be provided
using gas heaters designed to a set point temperature of 50°F. Each bulk storage room will be ventilated
separately with exhaust fans designed to provide 1 cubic foot per meter(cfm) per square foot exhaust. The
Electrical Room and the Chemical Offloading Rooms will be equipped with a through-the-wall packaged
AC unit.
18.4.2 New Pre-Chemical Feed Building
Heating and ventilation will be provided throughout this building. Heating will be provided using gas heaters
designed to a set point temperature of 50°F. The facility will be ventilated with exhaust fans designed to
provide 1 cfm per square foot exhaust.
18.4.3 Existing Filter Gallery Improvements
The existing HVAC ductwork in the filter pipe gallery must be demolished to accommodate a new
backwash supply piping. Therefore, the entire HVAC system, including the central station air handler,
condensing unit, and piping will also be demolished. Multiple new 3.5 ton mini-split ductless AC units will
be installed throughout the pipe gallery to provide conditioning.
18.4.4 Existing Chemical Bulk Storage Improvements
Per discussions on reducing chlorate formation in the bulk sodium hypochlorite tanks in Section 14, it is
recommended that the existing bulk storage space be conditioned to a temperature of 75°F. The proposed
improvements include the following:
• Demolition of existing fan and ductwork.
• Installation of 5,000 cfm air handling unit and fans.
• Installation of new air register and ductwork.
• HVAC controls.
18.4.5 New Training Facility
Air conditioning will be provided for the new training facility by a roof mounted DX single package unit with
gas heat, this unit will provide ventilation air and will modulate outside air based on building occupancy.
Plumbing will be provided for restroom facilities.
18.4.6 Outdoor Conditions
Table 18-7 lists the applicable outdoor conditions.
Hazen and Sawyer I Support Systems 18-27

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Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
• Backflow building does not have restroom facilities.
• Restrooms on first floor are accessible only by entering into process area.
Providing a larger conference room to accommodate a maximum occupancy of 60 to 70 people in the
existing Operations Building is challenging. For capacity greater than 50 people, the N.C. Building Code
deems this as an assembly area and upgrades throughout the Operations Building would be required,
including exits, possible fire sprinkler system, and changes to wall fire ratings.
A new training facility is recommended as an annex to the backflow training facility (Figure 18-12). The
benefits of this approach are that non-staff would not have access to secured process areas in the WTP. A
training room could be constructed to provide the desired occupancy of 60 to 70 people. The facility will
have a lobby entrance with a corridor that connects the training room to the existing BFP Training room. A
server/video room and a chair/table storage room would be located off the training room. Additionally, the
new training facility will provide amenities that can be beneficial during emergency events such as
hurricanes when employees are at the WTP for longperiods of time. New restrooms each equipped with
locker room and showers would be located off the corridor. A kitchen with a large pantry and eating area
will provide ample space for staff during breaks.
Modifications to the existing operations building would focus on the 2nd floor as shown in Figure 18-13. The
existing operations supervisor office will be demolished to allow expansion of the women's restrooms.
Each restroom would include lockers and a shower. The operations supervisor office would be relocated to
the existing filter gallery adjacent to the existing control room. The control room would be expanded
allowing for an improved layout of operator workstations. Additional storage area could be placed adjacent
to the control room. The existing laboratory will be renovated, including replacement of the aging casework
and modifications of the space to improve workflow and allow for additional analytical capabilities.
The GUC Phase 1 WTP Improvements will include the following new facilities:
• New Chemical Bulk Storage Building
• New Pre-Chemical Feed Building
• New Training Facility
New buildings will be designed to match and coordinate with existing building architecture. The
improvements and new facilities will be designed in accordance with the current N.C. Building Codes. The
training facility and modifications to the existing bathroom, office, and laboratory will be designed to meet
accessibility codes. Process areas will be considered work areas or equipment spaces in according with
the Accessibility Codes and will not be fully accessible.
Hazen and Sawyer I Support Systems 18-24

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
The existing SCADA software shall be used for this project. Discussions with the current GUC integrator
indicated that the software has adequate database space to accommodate the new I/O. HMI Screens will
be either modified or created for each new process provided as part of this expansion project. The existing
SCADA system also provides detailed electrical power monitoring and electrical circuit breaker statuses for
all of the major electrical power distribution equipment at the plant. The SCADA system will be updated as
part of this project to include all new major electrical power monitoring and breaker statuses, as well as
modify the SCADA single line diagrams to reflect electrical modifications which are part of the project, as
required.
The existing data historian and trend files will be updated to include all new mechanical processes and
electrical power monitoring. Modifying existing reports or the creation of new reports that are required by
GUC in conjunction with the expansion as well as power monitoring will be included in this project.
All PLC, communication, and appurtenant hardware or software that will be required on this project will be
coordinated with GUC staff and, where applicable, provided by GUC's preferred integrator. Further details
regarding preferred instrumentation manufacturers, types of instruments, and other specific details will be
addressed during the detailed design phase of the project via workshops with GUC and GUC's preferred
integrator.
18.2.3 Location of Existing and Proposed Facilities
The proposed locations of new SCADA system components are shown in Figures 18-4 through 18-7 as
part of the electrical equipment locations. The locations are not drawn to scale. Rather, these illustrations
are representative footprints of the approximate location of the new PLCs and remote I/O equipment. The
existing ring configuration will be modified to include the new components in a manner that is logical based
upon the required new electrical duct banks proposed as part of the project. All new SCADA system
interconnections will utilize fiber optic cable.
18.3 Architectural
Hazen met with GUC staff to discuss future administrative, laboratory, and office space needs at the WTP
and the following needs were identified:
• Existing control room layout restricts optimal operator workstation layout.
• Break room cannot accommodate kitchen facilities and seating needed to support staff
needs during emergency operations.
• Women's restrooms are too small to accommodate current and future staff needs.
• Existing conference room cannot accommodate current WTP staff or handle regional
meetings.
• File storage room is on first floor away from staff offices and more vulnerable to flooding.
• General storage throughout WTP does not meet current needs.
• Laboratory may not accommodate future analytical or staff office needs.
Hazen and Sawyer I Support Systems 18-23

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
• Control Room (old) Fast Track PLC
18.2.2 Proposed Modifications to the Existing SCADA System
The proposed modifications for this improvements project will continue with the plant's existing approach in
providing new strategically located PLCs for the major process areas. Table 18-6 provides a summary of
the proposed modifications. In discussions with the current GUC integrator and WTP staff, GUC is in the
process of standardizing on SCADA equipment at this plant and throughout their other plants. This project
will remain consistent with that approach and each new PLC will be the Modicon M580 Process
Automation Controller(PAC)with. Remote I/O racks shall be considered where appropriate to provide a
cost effective alternative to each new PLC having a PAC. New PLC's and remote I/O racks will be
installed on elevated or second story environmentally controlled mezzanine locations. Ideal will be for PLC
controllers to be located in the upper(Proposed) New Filters and Filter Gallery area (FIGURE 18.5) or in
the present Filters and Filter Gallery area near the current Server room. This will minimize the likelihood of
damage from flooding and free from chemicals and filter piping area contamination. All interconnections
between the existing ring, new PLCs, and new RIOs will be Ethernet copper(preferred) and/or fiber
depending upon physical routing of the connections.
The Raw Water Pump Station PLC (PLC-7)will be added to the current PLC fiber optic ring. New fiber
cable will be routed to and from the central Ethernet hub located in the existing Server office of the
Operations Building. The inclusion of PLC-7 into the ring will require a significant electrical duct bank to be
included in this phase of the project. PLC-7 will be connected to the fiber ring utilizing an Ethernet switch
located in the ozone electrical building in PLC-8. The Ethernet switch in PLC-8 shall be evaluated during
design to ensure that there is adequate port space to accept PLC-7.
Table 18-6: Proposed New Programmable Logic Controllers
Ring
Equipment Location Manufacturer Connections Connections
PLC-9 New clearwell pump Modicon M580 Existing ring • New signals in
station clearwell pump
station
• Remote I/O 9-1 (new
floc/sed and rapid
mix chemical
building)
RIO-9-1 New floc/sed and Modicon M580 New PLC-9 • New signals in
rapid mix chemical floc/sed area
building
PLC-10 New filter pipe Modicon M580 Existing ring • New signals for all
gallery filters
RIO-1-2 New chemical Modicon M580 Existing PLC-1A • New signals for
storage facility and PLC-1 B chemical systems
Hazen and Sawyer I Support Systems 18-22
1

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 18-5: Existing Distributed PLCs
Equipment Location Manufacturer Ring Connections Radial Connections
PLC-6-1A, Filter pipe gallery Modicon • From Ethernet • Remote I/O 6-5
PLC-6-1B (west) Quantum hub to PLC-1A (maintenance/
and PLC-1 B electrical/generator
• To PLC-6-1A building)
and PLC-6-1B • Filter 1&2 Remote I/O
• Filter 3&4 Remote I/O
• Filter 5&6 Remote I/O
• Filter 7 Remote I/O
PLC-4-1A, Ozone facility Modicon • From PLC-6-1A • Ozone power supply
PLC-4-1 B Quantum and PLC-6-1 B unit No. 1 (PLC-2-1)
• To PLC-8 • Ozone power supply
unit No. 1 (PLC-2-2)
• Ozone power supply
unit No. 1 (PLC-2-3)
• Ozone destruct unit
remote (I/O 4-2)
PLC-8 Ozone electrical Modicon • From PLC-8 • Electrical power
building Quantum • To Ethernet Hub monitors and power
distribution
equipment
Radial PLC Connections
PLC-7 Raw water pump Modicon • From Ethernet • Raw water pump
station Mommentum Hub station
M1E • To Ethernet Hub
In addition to the Ethernet and/or fiber ring, individual, radial connections from several process-related
Operational Manufacturing Interface (OMI) terminals and operator interfaces are present throughout the
facility. These include, but are not limited to the following:
• Ozone Main Control Panel OMI
• Maintenance/Elec/Gen Building
• Chief Operator of Remote Facilities
• Maintenance Shop
• 10-Base-2 SCADA Ports
• Chief Operator
• Control Room TV
Hazen and Sawyer I Support Systems 18-21

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
18.1.18 Construction Sequencing
Plant operations must be maintained throughout construction of WTP upgrades. All proposed plant
electrical power distribution modifications support this requirement. The construction schedule will be
required to construct and deem any new electrical power distribution equipment operational prior to the
process-mechanical equipment supported by that equipment to operate. This will be critical for the raw
water pump station modifications and the new electrical equipment associated with the clearwell/high
service pump station modifications.
18.1.19 Future Electrical System Recommendations
The report outlines a proposed plan for upgrades to the existing electrical power distribution system to
accommodate future WTP expansions. It should be noted that portions of the electrical power distribution
modifications may potentially be deferred to a later date. This PER is designed to explore all possible
options for each section of the electrical distribution system; however, a holistic view of the electrical
system will be revisited during detail design to determine the best strategy moving forward.
18.2 Instrumentation and Control
18.2.1 Existing SCADA System
The WTP existing control system currently consists of distributed Schneider Electric Modicon Quantum
programmable logic controllers (PLCs) that are strategically placed throughout the facility and
communicate using Ethernet copper and/or fiber optic cable connections. In April 2014, Modicon released
its Unity Pro hardware processors. All non-Unity Modicon Momentum and Quantum CPUs will be obsolete
as of May 31, 2015. After this 2015 date, the Momentum and Quantum CPUs will no longer be sold as new
products, however, service by replacement or repair will be available for eight years post 2023. PLC
processor selection for this project shall be based on providing the most current processors compatible
with the existing SCADA system.
The majority of the plant PLCs are connected in a ring configuration with connections to/from a central
Ethernet hub located in the existing control room of the Operations Building. The raw water pump station's
PLC (PLC-7) is connected to the Ethernet hub on an independent loop due to its physical location being
remote from the rest of the WTP. Further details for the existing distributed PLCs are summarized in Table
18-5.
Table 18-5: Existing Distributed PLCs
Equipment Location Manufacturer Ring Connections Radial Connections
Ring PLC Connections
PLC-1A, Filter pipe gallery Modicon • From Ethernet • Antenna
PLC-1 B (east) Quantum hub to PLC-6-1A • Remote I/O 1-1
• To PLC-6-1A (chemical storage
and PLC-6-1 B electrical room)
Hazen and Sawyer I Support Systems 18-20

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
2000
1500kVA Transformer and 2000A Bus
1500
a •/ 1200A Bus and Both Transformers
a 1000 Ex. Bus Rating
Ex. 500/66 Transformer
500
0
Existing 32 MGD 38 MGD 45 MGD
Expansion Options
•MCC-6 •MCC-7
Figure 18-11: Raw Water PS Electrical Load Expansion Scenarios
The new upgrades will require a new medium voltage electrical duct bank will be provided from the SWGR-
MAIN lineup to two new 1500kVA liquid-filled pad mounted transformers at the raw water pump station.
The secondary sides of the new raw water pump station transformers will supply a new 480VAC, 3-phase,
3-wire, 2000A, main-tie-main configured, motor control center labeled MCC-7/8. Slightly modifying the
MCC numbering of the new lineup will alleviate some duplicate numbering situations within the WTP.
The new motor control center MCC-7/8 will be provided with new starters for all existing equipment that will
remain unchanged as part of the project, as well as new starters for all equipment that will be upgraded or
added as part of the project. The upsize in the electrical distribution system will be able to accommodate all
upgrades, up to and including the 45 mgd expansion.
18.1.17 Location of Proposed Facilities
The proposed locations of electrical facilities are illustrated in Figures 18-4 through 18-7. The locations are
not drawn to scale. Rather, these figures represent the footprint of the approximate location of the motor
control centers, new transformers, and new starter equipment
Hazen and Sawyer I Support Systems 18-19

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
18.1.14 Chemical Area Modifications
A new chemical storage facility will be required. Dual electrical feeder circuits from existing MCC-3/4 will
supply power to a new main-tie-main motor control center, MCC-13/14. The new 480VAC, 3-phase, 3-wire,
600A motor control center will be physically located within the chemical storage facility. Motor control
center MCC-13/14 will electrically supply the starters associated with the new metering pumps, chemical
transfer pumps, and miscellaneous building loads (lighting, receptacles, and HVAC). These loads are
relatively small in size, although there are numerous starters required. Preliminary calculations indicate the
added load to MCC-3/4 will be roughly 90A, which will bring the total load of MCC-3/4 to 250-300A, which
is below the existing equipment ratings.
18.1.15 New Clearwell Pump Station Additions
A new set of clearwell pumps will be required. Dual electrical feeder circuits from new liquid filled pad-
mounted transformers will supply power to a new main-tie-main motor control center, MCC-11/12. The new
480VAC, 3-phase, 3-wire, 1600A motor control center will be physically located as part of the new pump
station required for the new pumps. Motor control center MCC-11/12 will electrically supply the starters
associated with the new intermediate pumps, future backwash pump, and miscellaneous building loads
(e.g., lighting, receptacles, and HVAC).
18.1.16 Raw Water Pump Station Modifications
The existing raw water pump station contains four existing raw water pumps, each equipped with a 150 HP
motor. Raw water pumps and their respective motors will be upgraded as required to accommodate each
WTP capacity increment. A detailed analysis of pump modifications required at each stage is provided in
Section 8.
The existing pair of 500 kVA liquid-filled, pad mounted transformers at the raw water pump station, the
associated motor control centers, and starters for the existing pumps are currently operating close to rated
capacity. Per Figure 18-11, the electrical equipment for any upgrade scenario will require the electrical
equipment to be upgraded to accommodate the increase in electrical load. In addition to the electrical load
increase, the proposed location of the new structures will be physically located in conflict with the existing
raw water pump station feeder. The feeder will be required to be replaced and routing reconfigured for
these expansion increments.
Hazen and Sawyer I Support Systems 18-18

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
4,500
Ex. Bus Rating
4,000 ------ —, —�—,�—
■US-1 ■US-2
3,500
3,000
Q 2,500
U,
Q
< 2,000
1,500
1,000 II
500
0
Existing 32 MGD 38 MGD 45 MGD
Figure 18-10: Unit Substation (US-1/2) Electrical Loads per Expansion Option (PP-6 Included)
18.1.12 Coagulation, Clarification, and Filtration
The expansion project will include additional coagulation, clarification, and filtration to accommodate the
increase in capacity. Dual electrical feeder circuits from new liquid filled pad-mounted transformers will
supply power to a new main-tie-main motor control center, MCC-9/10. The new 480VAC, 3-phase, 3-wire,
1200A motor control center will be physically located within the new pre-chemical feed building, adjacent to
the new rapid mix. Motor control center MCC-9/10 will electrically supply all new process loads within the
area, including rapid mixers, SuperPulsator equipment, filter equipment, pre-chemical storage and feed,
and miscellaneous building loads (e.g., lighting, receptacles, and HVAC).
18.1.13 Existing Clearwell Pump/High Service Pump Station Modifications
The expansion project will include the addition of a new clearwell pump station. As a result, minimal
upgrades will be required to the existing three clearwell pumps, located in the existing clearwell/high
service pump room. The existing 150 HP motors for the clearwell pumps are electrically supplied from a
single power panelboard, PP-6, located within the room. The electrical supply to the pump station will also
be improved. A new feeder will be provided to the pump station and a new automatic transfer switch will be
installed to select the best source to supply PP-6.
Hazen and Sawyer I Support Systems 18-17

f
Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
18.1.10 High Service and Backwash Pump Modifications
The existing high service pumps are adequately sized to handle most of the expansion scenarios. For the
38 mgd and 45 mgd expansion, high service pump No. 2 may be required to increase from 450 HP to
500 HP. This increase in motor size may require the starter to be replaced, but the overall power
distribution system will remain as-is. In the event that the system is compromised, a spare breaker can be
replaced with minimal downtime. GUC indicated that spare breakers are stored on-site.
Alternatively, a new fused tie switch could be added to the MV-MCC-1 and MV-MCC-2 power distribution
equipment. The tie switch would provide main-tie-main capability to this critical equipment and increase
system reliability.
18.1.11 Electrical Distribution Modifications— Low Voltage
The existing electrical distribution system includes the WTP's main low voltage power distribution lineup,
unit substation US-1/2. US-1/2 will remain the major source of power for the existing WTP, but the new
5 kV primary loop will handle a majority of all new loads provided as part of the expansion project. US-1/2
is currently operating at a little more than half of the rated capacity. Adding the additional loads to US-1/2
will not greatly affect the overall the operating load of US-1/2 (refer to Figure 18-10). The modifications to
US-1/2 for this project will mainly include an additional circuit breaker to"dually" supply the critical loads of
Power Panel PP-6 (primarily the clearwell pumps). This addition does not necessarily increase the load on
the existing lineup, but it increases the reliability of the electrical system. The proposed approach to add
the second feed to PP-6 is shown on the single line diagrams using an automatic transfer switch, but this
can also be accomplished using a manual transfer switch or double-throw disconnect switch. The details of
the switch used will be determined as part of the detailed design.
Hazen and Sawyer I Support Systems 18-16

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
A summary of issues related to the expansion to 32 mgd, 38 mgd, and 45 mgd is as follows:
• Existing MV-SWGR-MAIN lineup is well suited for all expansion alternatives up to 45 mgd.
• Existing A-side utility (2-2500kVA transformers) is capable of operating the entire plant if
the B-side utility (1-2500kVA transformer) is out of service.
• Existing B-side utility (1-2500kVA transformer) is not capable of operating the entire plant if
the A-side utility(2-2500kVA transformers) is out of service. A second utility transformer
should be installed to meet this condition.
In summary, the existing top-end electrical power distribution system at the WTP is capable of handling the
electrical additions proposed as part of the plant expansion increments being evaluated. Coordination with
GUC staff should take place during detailed design to discuss the possibility of adding a second
transformer to the "B" side. For the 38 mgd and 45 mgd capacity expansions, the existing generator
capacity should be closely evaluated.
18.1.9 Coagulation, Clarification, and Filtration
The existing electrical distribution system includes three sets of feeder breakers within MV-SWGR-MAIN
and one pair of prepared spaces. Each circuit breaker on the"A" side is paired with a similar circuit breaker
on the"B" side to reliably supply power to the raw water pump station, Unit Substation 1/2, and MV-MCC-1
and MV-MCC-2. These load centers are in a main-tie-main configuration with the exception of the MV-
MCC's. Due to the amount of load that will be added to the system for the proposed expansion milestones,
a fourth set of medium voltage feeders are recommended.
The most conventional and recommended approach is to utilize the two existing medium voltage circuit
breakers within existing MV-SWGR-MAIN. This would be consistent with the existing electrical system's
power distribution configuration. The disadvantage to this option is that it would occupy the only remaining
physical space within the lineup. There is not adequate physical space on either side of MV-SWGR-MAIN
to add any additional sections.
The new fourth set of medium voltage feeders would be routed to two pairs of outdoor, medium voltage,
liquid filled, pad-mounted transformers. The medium voltage feeders will be located at the new clearwell
pump station and new pre-chemical feed facility, supplying MCC-9/10 and MCC-11/12, respectively. The
5 kV primary loop would utilize oil-immersed switches within the primary sides of each transformer to allow
isolation of the loop at any point. The new primary loop will also be configured to allow for the raw water
pump station transformers to be included in the loop as part of future expansion. This will provide flexibility
in the power distribution system by freeing up the current pair of feeder breakers within MV-SWGR-MAIN
which are dedicated to the raw water pump station.
Hazen and Sawyer I Support Systems 18-15

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
expansion capacity milestone discussed as part of this evaluation increases the expected electrical loading
on the existing electrical equipment as indicated in Figure 18-9.
14,000 -
■MV-SWGR-MAIN-A •MV-SWGR-MAIN-B
Ex. Bus Rating
12,000
10,000 -
8,000 -
1 Ex. Generat r
All Ex.Transformers
6,000 — Ex:8-Side Transformer
Ex.A-Side Transformers
4,000 -
All Ex.Generators
0
■
Existing 32 MGD 38 MGD 45 MGD
Figure 18-9: MV-SWGR-MAIN Electrical Loads per Expansion Option
A summary of existing conditions is as follows:
• Existing MV-SWGR-MAIN lineup is well suited for all expansion alternatives up to 45 mgd.
• Existing A-side utility(2-2500kVA transformers) is capable of operating the entire plant if
the B-side utility(1-2500kVA transformer) is out of service.
• Existing B-side utility(1-2500kVA transformer) is capable of operating the entire plant if the
A-side utility(2-2500kVA transformers) is out of service, although it will be slightly
overloaded.
• With either one of the generators running, a single existing generator is capable of
operating the entire plant without the presence of the utility.
Hazen and Sawyer I Support Systems 18-14
1

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 18-4: Calculated Additional Electrical Load per Capacity Milestone
Connected Operating Connected Operating Connected Operating
(kW) (kW) (kW) (kW) (kW) (kW)
Electrical Service 1 3,932 2,533 4,305 2,833 4,477 2,970
(Plant A side)
Electrical Service 1 3,865 2,114 3,999 2,224 4,342 2,394
(Plant B side)
Total 7,797 4,647 5,057 8,819 5,364
Percentage 30% 42% 51%
Increase
The operating load values shown in the load list are calculated by multiplying the connected load by a
demand factor. The demand factor allows for the connected load values to be de-rated to approximate a
more realistic demand load. These demand factors also take into consideration the firm capacity of unit
processes. Firm capacity is the installation of multiple units of equipment(e.g., pumps) to handle the
design flow of the plant with the largest unit out of service.
The estimated total additional plant load to be served by the plant's electrical power distribution system for
the new facilities is 4,647 kilowatt(kW) for the 32 mgd expansion, 5,057 kW for the 38 mgd expansion, and
5,364 kW for the 45 mgd expansion. This is a 30 percent, 42 percent, and 51 percent increase from the
current existing operating load at the plant. The existing main medium voltage switchgear(MV-SWGR-
MAIN) has ample electrical capacity to supply power to the new facilities at all the evaluated capacity
increments. Capability of the existing configuration of electrical utility transformers and existing engine
generators, as well as physical limitations for MV-SWGR-MAIN.
The electrical load list is used as an electrical equipment sizing tool, which helps determine ratings of
electrical distribution equipment based upon a worst-case scenario methodology. It is beneficial for
equipment sizing but is inflated and not an accurate representation of what the size should be for the
electrical utility. Other methodologies of determining expected utility and generator future demands are
used, which utilize actual utility billing information. The upgrades will require additional power transformers,
motor control centers, and power panelboards to be located in the proposed process facilities.
Modifications to the existing MV-SWGR-MAIN feeder circuit breakers and feeder conductors will be
required to supply the proposed equipment.
18.1.8 Electrical Distribution Modifications — Medium Voltage
The existing electrical distribution system includes multiple electrical utility sources, generator sources, a
medium voltage switchgear lineup, and associated feeder breakers to supply power to all loads throughout
the WTP. As indicated through electrical utility bills and the electrical load list, the current electrical load at
the WTP is well within the parameters of all existing electrical sources. The electrical power distribution
equipment is also rated much higher than the actual existing load realized by the plant. Each WTP
Hazen and Sawyer I Support Systems 18-13

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
18.1.6 Historical Electrical Utility Data
Historical utility data was acquired from GUC staff and is being used for reference in the development of
the electrical power distribution system upgrades. Specifically, GUC staff provided demand load and usage
information for the plant covering the time period from January 2015 to December 2016. The peak demand
information is provided in Figure 18-8. The maximum monthly peak demand of 1,666kW occurred during
the March 2015 billing period. This value is the sum of peak demands for the two utility supplies for that
billing p eriod.
laubwg,Overall Utility Demand (MO —Peak Demand
1700
1650
Peak = 1,666kW
- 1600
c
E 1550
m
0
1500
E- 1450
II 400 - -
1350
1300
1250
Date
Figure 18-8: Monthly Peak Electrical Utility Demand
18.1.7 Proposed Modifications to the Existing Electrical System
An electrical load list was created, detailing the existing plant loads and proposed new loads for each
proposed capacity increment. This list provides information used for the development of the proposed
modifications to the plant's electrical power distribution system. The load information is summarized in
Table 18-4.
Hazen and Sawyer I Support Systems 18-12

1
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FIGURE 18.6
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FIGURE 18.5
0
Hazen PARTIAL SITE PLAN
i

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Li
B Hazen OVERALL SITE PLAN
R

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 18-3: Existing Low Voltage Single-Ended Loads
Electrical
Equipment Location Manufacturer Ratings Major Loads
US 1 Loads
MCC-5 Main electrical Square D 480VAC, 600A, • Generators
room Model 6 Motor One main breaker • Storage building
Control Center
• Building loads
MCC-6 East side filter Square D 480VAC, 1200A, • Fluoride
gallery Model 6 Motor no main • Sampling pumps
Control Center overcurrent device
• Rapid mix
• Administration area
building loads
US-2 Loads
PP-5 Maintenance Square D 480VAC, 800A, • Maintenance shop
shop One main breaker loads
PP-6 High service Square D I-Line 480VAC, 800A, • Intermediate pump
pump room Panelboard One main breaker VFDs
• Building loads
Hazen and Sawyer I Support Systems 18-7

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
(4.16kVAC-480/277VAC); a fixed, molded case, main power circuit breaker; a tie power circuit breaker;
and a switchgear distribution section. This configuration allows each main power circuit breaker to provide
power to it's respective (e.g. "A" side) distribution section. Power can be supplied from the"A" side to the
"B" side (or vice versa) through use of the tie power circuit breaker. A kirk-key interlock scheme
mechanically determines which power supply is providing power at any given time. Unit Substation
locations, ratings, main-tie-main low voltage motor control centers, and descriptions are summarized in
Table 18-2. Table 18-3 provides a summary of the low-voltage single-ended loads. The physical location of
all the major electrical equipment described above is shown in Figures 18-4 through 18-7.
A large majority of loads supplied from US-1 are dually supplied (e.g. utilize a feeder from the"A" side and
the"B" side of US-1), which adds optimal reliability to the electrical distribution system. There are, however,
a few loads that are single-ended, which would require all loads supplied from that feeder to be shut down
in the event of a failure or periodic maintenance.
Table 18-2: Existing Low Voltage Power Distribution Equipment
Electrical
Equipment Location Manufacturer Ratings Major Loads
US-1/2 Low voltage Square D Power 480VAC, 4000A • MCC-1/2
electrical room Zone III main-tie-main • MCC-3/4
• Single-ended loads
(refer to table 18-3)
MCC-1/2 Ozone electrical Square D 480VAC, 2000A • Ozone equipment
building Model 6 Motor main-tie-main • PP-1
Control Center
• PP-2
• PP-3
• Sedimentation basin
No. 5
• Sedimentation basin
No. 6
MCC-3/4 Chemical Square D Model 480VAC, 1200A • Chemical storage
storage building 6 Motor Control main-tie-main equipment
Center • PP-4
• Sedimentation basins
No. 1-7
Hazen and Sawyer I Support Systems 18-6

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
located in the maintenance shop, adjacent to the main electrical control room. MV-MCC-1 is electrically
connected to the"A" side of MV-SWGR-MAIN and consists of a Reduced Voltage Autotransformer Starter
(RVAT) for high service pump No.1 and a full-voltage starter contactor for backwash pump No.1.
MV-MCC-1 is bus-tapped and supplies a stand-alone MCC structure, which consists of a full-voltage
starter contactor for high service pump No.2. The feeder supply to MV-MCC-1 is directly connected to the
bus bars with no main overcurrent protection device. MV-MCC-2 is electrically connected to the"B" side of
MV-SWGR-MAIN and consists of RVATs for high service pump No.3 and high service pump No.4. The
feeder supply to MV-MCC-2 is also directly connected to the bus bars with no main overcurrent protection
device. MV-MCC-2 is the older of the two high service pump motor control centers, but both are still in
good condition and have been well maintained.
It should be noted that both MV-MCC-1 and MV-MCC-2 are not electrically tied together and that single,
radial feeders from MV-SWGR-MAIN supply each MV-MCC. In this configuration, a single failure has the
potential of taking out an entire MV-MCC lineup and all associated loads (worst case HSP-1, HSP-2, and
the backwash pump). Medium voltage power distribution equipment locations and ratings are listed in
Table 18-1. Table 18-1 includes descriptions for the major loads supplied from each equipment lineup.
Table 18-1: Existing Medium Voltage Power Distribution Equipment
Electrical
Equipment Location Manufacturer Ratings Major Loads
MV-SWGR-MAIN Main electrical Square D 4160VAC, • Unit substation
room Masterclad 2000A, US-1/2
switchgear Main-tie-main • MV-MCC-1
• MV-MCC-2
• Raw water pump
station
MV-MCC-1 Maintenance Square D IsoFlex 4160VAC, • High service pump
shop Motor Control 600A, No main No. 1
Center overcurrent • High service pump
device No. 2
• Backwash pump
MV-MCC-2 Maintenance Square D IsoFlex 4160VAC, • High service
shop Motor Control 600A, No main pump No. 3
Center overcurrent • High service
device pump No. 4
18.1.5 Existing Electrical Distribution — Low Voltage
Unit substation (US-1/2) is supplied directly from MV-SWGR-MAIN. The lineup is physically located in the
room adjacent to the Main Electrical Room to provide power to local process equipment. Unit Substation
US-1/2 consists of a metal enclosed, fusible, load interrupter switch; a dry-type step-down transformer
Hazen and Sawyer I Support Systems 18-5

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Figure 18-3: Utility Pad-Mounted Transformers
18.1.3 Existing Main Switchgear— Medium Voltage
The Square D Masterclad 4.16kVAC, main medium voltage distribution switchgear lineup(MV-SWGR-
MAIN) is arranged in a main-tie-main configuration creating an "A Bus" and a"B Bus". Each medium
voltage, electrically operated, draw-out power circuit breaker on the"A" side is paired with a similar circuit
breaker on the"B" side to reliably supply power to the unit substation and raw water pump station. The high
service pumps and backwash pump are medium voltage loads, which are radially supplied from this lineup
as well, via Square D Isoflex motor control centers.
The main MV switchgear lineup(MV-SWGR-MAIN) consists of two main utility breakers, one tie breaker,
two main generator breakers, and distribution feeder breakers. Each breaker is equipped with a power
monitor and the appropriate Schweitzer Engineering Laboratories (SEL) protective relay to suit the
application. The lineup also consists of an SEL bus differential relay protection scheme in a high
impedance configuration. The main MV switchgear lineup has utilized all but one available space in the
existing electrical room and there is one pair of spare breakers. Physically, there is no space to add
additional switchgear sections to either end of the lineup.
18.1.4 Existing Electrical Distribution — Medium Voltage
The other medium voltage distribution equipment at the WTP are the Square D Isoflex motor control
centers for the high service pumps and backwash pump. These two motor control centers (MCCs) are
Hazen and Sawyer I Support Systems 18-4

NOTES:
PROVIDE NEW ATs R HIGH SERVICE MP
(SEE FIGURE IC ROMFROM TX-SUB-2 ((SEE W.F.., BU Alm.STATION LOAD REDUNDANCY.
F ~(SEE FIGURE ICI) (SEE FIGURE 18.1) 2.PROVIDE NEW MV LOOP FOR NEW PROCESS
LOAD CENTERS.
UNIT SUBSTATION I —UNIT ARSJLT OM A
NOOOAf .... "..noon, P -_ jK'ADaoAr
US-S-SWAM.WOO,30.3W.NOOOA.55IU N.O. US-3-SWL#,NOV.3W,SW,AODRt UREA
: : 1600eT :) 800AT 2OWAi III 3000AT BDDAT800 Ai U
io1r zD MCC-1,MAC a:r r
W,lw,: N new,3D,1w,30o0A
aaoA P.
gx.O. cc-x, -. e�AF (LOCATED IN HIGH SERVICE PUMP ROOM)
(30GTED IN OZONE ELECTRICAL BUILDING)
t> I) ISoo.Tl) PP, vas,.eov.30 w
I 1 WAF 35oAF�.,.. i50AF
XCC-3,Nw,10.TY,IE0w1 _. - ' MCC-4.<eov.30,3w,IS00A (LOCATED IN ISOAT 350 iBOAT
• WP)
P. SOOUF) HanTExAxCFS TRtWP-t TK{WP-Z TD-TIME-I
O00 IISNVA 17 1 ITSRVA
----- I _ (LOCATED IN CHEMICAL STORAGE swum.) ABO'ANOV NOISw ASO�eov
IF-
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:O.:)I I SAT DRTTRSOs MP TIMMS DWI TUNS
ACC-s Ae w.30 3w 1300A
IMOC-13,ABOV.30,3W,BOBA.-1N'T PIDC-IA,AWV,30,3Lv,e00A
AWAT (LOCATED IN FAST SIDE FILTER GALLERY) IN 1150 150 150
L $I2 i J
MOC-s,Nw,70,TV.BOOR (LOCATED III BULK CHEMICAL STORAGE BUILDING) TRAP TRAMSPER
MO x ERPUMP , PUMPFER
Ilnat®u WAIN a[curwL WOW)
NEW e00A
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/ I.00/,30,33:,13WA,-4•w,.3:°S:DDA1 GREENVILLE UTILITIES COMMISSION
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L !I i J I IBDDAF) FIGURE 18.2
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i

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
18. Support Systems
18.1 Electrical
This section will focus on the necessary modifications to the existing electrical power distribution system at
the plant. Modifications to the system are necessary to supply the new plant loads associated with the
expansion project, including modifications to the existing Raw Water Pump Station, addition of new rapid
mixers, SuperPulsators, and filters, modifications and additions of new clearwell pumps, addition of
chemical facilities, and modifications to the existing high service pumps.
18.1.1 Existing Electrical System
A single-line diagram of the existing plant electrical power distribution system is provided in Figure 18-1
and Figure 18-2. The WTP is supplied by one 12.47kVAC incoming utility service, which supplies two on-
site medium voltage switchgear lineup of fused switches. One fused switch supplies a pair of 2500kVA
transformers to create the"A side" utility supply. The second fused switch supplies a single 2500kVA
transformer to create the"B side" utility supply. An existing concrete pad with conduit stub-ups has been
installed for when a fourth utility transformer is required (illustrated in Figure 18-3). Both utility supplies step
down the utility distribution voltage of 12.47kVAC to the WTP main distribution voltage of 4160VAC. The
4.16kVAC sources provide power to the WTP's main medium voltage (5kV)distribution switchgear
(MV-SWGR-MAIN) located in the Main Electrical Building.
18.1.2 Existing Standby Generator System
In addition to the dual utility sources, GUC owns and operates two Caterpillar 1600kW prime rated,
4.16kVAC, diesel engine-generator sets. These generators are electrically connected to each side of the
medium voltage distribution switchgear lineup via breakers to supply power to the plant during utility
outages. The generators are physically located in a room adjacent to the medium voltage switchgear
electrical room in the Main Electrical Building.
The diesel engine-generator sets have appropriate exhaust after treatment to allow the units to be utilized
in coordination with GUC staff. The existinggenerator controls are set upfor
in non-standby scenarios
Y
closed transition between normal utility power and generator power, with the capability of paralleling the
two generator sets together in the event the main switchgear tie breaker is required to be closed.
Hazen and Sawyer I Support Systems 18-1

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
25,000 -
Alt 1 Lagoon Projections (8% Solids)
—Alt 3 Lagoon Projections (8% Solids) s 1":''
20,000 - —Alt 4 Lagoon Projections (8% Solids) , a4,.
U ,,3*
co 15,000
J
0
to
Z r-.,W- -'may-r
To 10,000 - -
Q -
5,000 -
w'r%'
I I I
2015 2020 2025 2030 2035 2040 2045 2050 2055
Figure 17-13: Annual Dry Solids Volume to Lagoon Comparison for Alternatives
Hazen and Sawyer I Residuals Management Facilities 17-28

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 17-12 provides the capital costs, net present value, and annual O&M costs for Alternatives 1, 3,
and 4. Life cycle costs for both 20 year and 30 year were evaluated. Alternative 2 was not included for
analysis due to the existing lagoon capacity results. All alternatives include O&M costs for solids dredging
and disposal. Alternatives 3 and 4 also include O&M costs for power, belt replacement, and labor. The
solids dredging and disposal cost savings realized with dewatering facilities are outweighed by these
additional O&M costs. Additionally, the capital costs are significantly higher for Alternatives 3 and 4.
Hazen recommends GUC staff select Alternative 1 and continue to send all residuals streams to the
existing lagoon. Hazen recommends that GUC staff annually dredge new solids that are collected to
maintain the current lagoon functionality and capacity. Options for annual solids removal and disposal
should be explored. Upon selection, Hazen recommends that GUC staff issue a request for proposals for
one year of solids removal. Implementation will provide GUC staff with information specific to their lagoon
including cost, operation time, and solids characteristics. The information gathered will allow the estimated
costs to be refined for future annual dredging and disposal.
Table 17-12: Residuals Management Capital and O&M Cost Comparison
Alternative 1 — Alternative 3— Alternative 4—
Scenario Existing Lagoon 1 Dewatering /Lagoon 1 Dewatering /Lamella 1
Capital Cost $1,540,000 $11,700,000 $14,600,000
20-Year Life Cycle Cost
Net Present Value $7,620,000 $18,500,000 $22,600,000
Annual O&M $350,000 $390,000 $460,000
30-Year Life Cycle Cost
Net Present Value $11,100,000 $22,400,000 $27,100,000
Annual O&M $400,000 $440,000 $520,000
' Cost expressed in 2016 dollars.
Hazen and Sawyer I Residuals Management Facilities 17-27

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
17.4 Recommended Improvements
Alternatives 3 and 4 would result in a significant reduction in the solids volume to the residuals lagoon
(Figure 17-13). Alternatives 3 and 4 include off-site disposal of dewatered solids from the thickening and
dewatering facilities. This is expected to reduce O&M costs of solids disposal by reducing the amount of
dredging required. In January of 2017, GUC had a laboratory provide metals analysis for sludge in the
residuals lagoon. The North Carolina Department of Environmental Quality(NCDEQ) Division of Waste
Management reviewed the analytical results and concluded that the material can go to a Municipal Solid
Waste Landfill for disposal but it"cannot be disposed at a landfill permitted for Land Clearing and Inert
Debris".
Hazen compiled the 2012 Master Plan and updated the dredging, dewatering, and disposal costs for the
life cycle cost comparison of the alternatives. An estimate of the residual disposal costs are provided in
Table 17-11. The costs have a wide range based on numerous factors, including level of dewatering,
disposal location, and level of involvement by GUC staff. For the life cycle cost analysis, it was assumed
that lagoon solids would be dredged and land applied at 8 percent solids for$400 per dry ton. It was
assumed the belt filter press solids would be disposed of at$250 per dry ton.
Table 17-11: Summary of Residuals Disposal Costs
Solids Concentrations Cost Opinion Source
Dredging at 8%Solids
Cost Estimate $142-$215/dry ton Land and Marine Supply, LLC, 2016
Cost
Dredging and Land Application at 8% Solids
2012 Master Plan $310/dry ton Synagro
Local Utility Bid $400/dry ton Synagro 2014 Cost
Dredging, Dewatering, and Composting at 20%Solids
2012 Master Plan $750/dry ton McGill Environmental
Cost Estimate $750-$1000/dry ton McGill Environmental 2016 Cost
Disposal at 20% Solids
Cost Estimate $168/dry ton Republic Services' (Aulander, NC);
Assumes GUC will provide
transportation and includes estimated
fuel costs
Cost Estimate $250/dry ton Hazen project experience
'Municipal Solid Waste Landfill, as recommended by NCDEQ
Hazen and Sawyer I Residuals Management Facilities 17-26

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
9,000 -
—Lagoon Projections (8% Solids)
8,000 -
—Belt Filter Press Solids Projections (20% Solids)
7,000 -
6,000 - Yti.....
•ram
U
N 5,000 -
70
is aE
fn '-Y
4,000 - .
� e
c
< 3,000 -
2,000 -
1,000 -
2015 2020 2025 2030 2035 2040 2045 2050 2055
Figure 17-12: Alternative 4 Annual Dry Solids Volumes to Lagoon and Dewatering Projections(High and Low Average Day Demand)
Hazen and Sawyer I Residuals Management Facilities 17-25

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
BLOWDOWN EQ BASIN
0 r LAMELLA EQ BASIN
r r r
Ar .
• �A THICKENER - -__,.
6 . . LAMELLA
0
DEWATERING
f_ FACILITY
CHEMICAL
FACILITY €µ
Figure 17-11: Alternative 4 Solids Thickening, Dewatering, and Backwash Clarification Site Plan
Hazen and Sawyer I Residuals Management Facilities 17-24

1
Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
RAW WATER WATER TREATMENT FACILITIES FINISHED,
WATER
SUPERPULSATOR 1 SED BASIN FILTER BW / FTW
RESIDUALS i 1 RESIDUALS
• • ♦ TO LAGOON OR
7 TO PLATES ,' RECYCLE
- EQ EQ LAM TES
BASIN �- BASIN PLATES
-- TO EQ BASIN TOTAL TO LAGOON
TO THICKENERS ���
OVERFLOW TO LAGOON
GRAVITY FILTRATE TO LAGOON
THICKENER
J DEWATERING
ff _...
SOLIDS DISPOSAL
FROM THICKENER
Figure 17-10: Alternative 4 Solids Thickening, Dewatering, and Backwash Clarification Residuals Process Flow Diagram
Hazen and Sawyer I Residuals Management Facilities 17-23

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 17-10: Summary of Alternative 4 Solids Thickening, Dewatering, and Backwash
Clarification Equipment Sizing
Design Criteria at Design Criteria at
Parameter Units Flow of 32 mgd Flow of 38 mgd
Blowdown Equalization
Required volume 1 gallons 435,800 435,800
Recommended volume gallons 450,000 450,000
Number of thickener feed pumps ---- 2 (duty/standby) 2(duty/standby)
Pump capacity gpm 385 430
Gravity Thickener
Number of units ---- 1 1
Diameter feet 70 70
Percent solids ---- 2% 2%
Average solids loading rate at average flow Ib/d•SF 1.63 1.95
Average hydraulic loading rate at average flow gpd/SF 143 161
Maximum month solids loading rate at Ib/d SF 2.73 3.25
average flow
Maximum month hydraulic loading rate at gpd/SF 143 161
average flow
Dewatering Belt Filter Press
Number of units ---- 2 2
Belt filter press size meter 2 2
Max solids loading rate lb/hrm•press 600 600
Total maximum solids loading rate lb/hr 2,400 2,400
Percent solids ---- 18—20% 18—20%
Average solids loading rate at average flow Ib/d•SF 800 950
Average hydraulic loading rate at average flow gpd/SF 18 22
Maximum month solids loading rate at Ib/d SF 1,340 1,590
average flow
Maximum month hydraulic loading rate at gpd/SF 31 36
average flow
Lamella Equalization Basin
Required volume 1 gallons 444,600 444,600
Recommended volume gallons 575,000 575,000
Number of pumps ---- 2(duty/standby) 2 (duty/standby)
Pump capacity gpm 360 360
Lamella Clarifier
Number of units ---- 1 1
Capacity gpm 695 695
Assume operation as summarized in Tables 17-1 and 17-7.
Hazen and Sawyer I Residuals Management Facilities 17-22

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
17.3.4 Alternative 4: Solids Thickening and Dewatering and Backwash Clarification
head fourth alternative includes clarifying all filter backwash and filter-to-waste for recycling to the of
the WTP. One advantage of this alternative would be a reduction in the total raw water flow from the Tar
River. Similar to Alternative 3, thickening and dewatering facilities would be provided for sedimentation
basin and SuperPulsator®blowdown. Figure 17-10 illustrates the process flow for the residuals streams.
Blowdown will be sent to an equalization basin, and then pumped to a gravity thickener. Overflow from the
gravity thickener will be diverted to the residuals lagoon. The dewatering facilities will typically be operated
only on weekdays. The gravity thickener will store thickened solids over the weekend. A belt filter press
dewatering facility would consist of feed pumps, a dry polymer feed system, and belt filter presses. Filtrate
from the belt filter presses will be sent to the residuals lagoon, while the dewatered cake will be disposed of
off-site.
The filter backwash and filter-to-waste will be sent to another equalization basin, which will be pumped to
Lamella plates for clarification. The overflow from the plates will be sent to the residuals lagoon. The solids
will be sent to the blowdown equalization basin for gravity thickening. Table 17-10 provides the equipment
sizing for Alternative 4 at the future plant capacity of 32 and 38 mgd. The gravity thickener was sized at a
solid loading rate less than 5 Ib/d.SF and a hydraulic loading rate less than 200 gpd/SF.
The equalization basins, Lamella plate unit, and gravity thickener are sized to handle the future 45 mgd
demand. The equalization basin pumps will need to be upsized to handle additional blowdown from a third
SuperPulsator'and additional backwash from the new filters. A third belt filter press will need to be added
when average plant flow is approximately 27.5 mgd to maintain less than 40 hours per week of dewatering
operation at average plant flow and maximum month solids loading. It is anticipated that a third belt filter
press will be required in approximately 2047.
The residuals management equipment can be located on the site between the WTP and the residuals
lagoon. Figure 17-11 illustrates a conceptual layout. The existing berm would need to be relocated around
the equipment to provide protection during flooding.
Future average day demand projections with conservation (e.g., high and low) were used with the average
solids loading rate to estimate future dry solids volume to the residuals lagoon and leaving the dewatering
facility under this alternative. Figure 17-12 illustrates the annual dry solids volume assuming 8 percent
solids to the lagoon and 20 percent solids leaving the dewatering facility between 2020 when start-up is
anticipated through 2050. The volume of solids to the lagoon for Alternative 4 is estimated to be
10.3 percent of Alternative 1.
Hazen and Sawyer I Residuals Management Facilities 17-21

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
8,000 -
—Lagoon Projections(8% Solids)
7,000 -
Belt Filter Press Solids Projections (20% Solids)
6,000 -
- 5,000 -
U
cn
72 4,000 -
0
cn .
c 3,000 -
c
Q -
2,000 -
1,000
2015 2020 2025 2030 2035 2040 2045 2050 2055
Figure 17-9: Alternative 3 Annual Dry Solids Volumes to Lagoon and Dewatering Projections(High and Low Average Day Demand)
Hazen and Sawyer I Residuals Management Facilities 17-20

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Wig
` , '~'-_ 1) BLOWDOWN EQ BASIN
4 J .1
THICKENER
4 ti P 1 / .4... t A' it, ,
r
DEWATERING
FACILITY ,
w
:-%
r'
CHEMICAL :"` M'
FACILITY
el*
Figure 17-8: Alternative 3 Solids Thickening and Dewatering Site Plan
Hazen and Sawyer I Residuals Management Facilities 17-19

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
RAW WATER FINISHED
WATER TREATMENT FACILITIES -
WAT E R
I I '
SUPERPULSATOR : : SED BASIN ; FILTER BW / FTW
RESIDUALS ' ' RESIDUALS
♦
EQ RESIDUALS
BASIN LAGOON
FILTRATE
OVERFLOW
GRAVITY
THICKENER
J DEWATERING
SOLIDS DISPOSAL
FROM THICKENER
Figure 17-7: Alternative 3 Solids Thickening and Dewatering Residuals Process Flow Diagram
Hazen and Sawyer I Residuals Management Facilities 17-18

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
2020 when start-up is estimated. The volume of solids to the lagoon for Alternative 3 is estimated to be
15 percent of Alternative 1.
Table 17-9: Summary of Alternative 3 Solids Thickening and Dewatering Equipment Sizing
Design Criteria at Design Criteria at
Parameter Units Flow of 32 mgd Flow of 38 mgd
Blowdown Equalization
Required volume 1 gallons 435,800 435,800
Recommended volume gallons 450,000 450,000
Number of thickener feed pumps ---- 2 (duty/standby) 2(duty/standby)
Pump capacity gpm 375 420
Gravity Thickener
Number of units 1 1
Diameter feet 65 65
Percent solids 2% 2%
Average solids loading rate at average flow Ib/d SF 1.80 2.15
Average hydraulic loading rate at average flow gpd/SF 163 182
Maximum month solids loading rate at Ib/d SF 3.01 3.58
average flow
Maximum month hydraulic loading rate at gpd/SF 163 182
average flow
Dewatering Belt Filter Press
Number of units ---- 2 2
Belt filter press size meter 2 2
Max solids loading rate Ib/hr m press 600 600
Total maximum solids Loading rate lb/hr 2,400 2,400
Percent solids ---- 18—20% 18—20%
Average solids loading rate at average flow Ib/d•SF 760 910
Average hydraulic loading rate at average flow gpd/SF 17 21
Maximum month solids loading rate at Ib/d SF 1,270 1,510
average flow
Maximum month hydraulic loading rate at gpd/SF 29 35
average flow
Assume operation as summarized in Tables 17-1 and 17-7.
Hazen and Sawyer I Residuals Management Facilities 17-17

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
17.3.2 Alternative 2: Construct New Lagoon
The second alternative is to abandon the existing residuals lagoon and construct a new lagoon for
residuals storage. The analysis indicated that the existing solids in the residuals lagoon do not need to be
dredged, so construction of a new lagoon is not necessary. In the event that a new lagoon is needed in the
future, Hazen assessed the new lagoon site alternatives recommended in the 2012 Master Plan. The
region to the west of the future pre-sedimentation impoundment site was identified as a potential lagoon
location. However, this site is in the 100-year floodplain and would present challenges for wetlands
permitting. The second location is an existing pond directly north of the residuals lagoon. It is estimated to
be 9 acres and the depth is unknown. The pond is privately owned (Parcel 24409) and a 2015 tax value
estimate was $55,840. This location is recommended for further consideration if a new lagoon is needed in
the future.
17.3.3 Alternative 3: Solids Thickening and Dewatering
The third alternative was to continue sending all filter backwash and filter-to-waste directly to the residuals
lagoon and provide thickening and dewatering facilities for the sedimentation basin and SuperPulsator®
blowdown to minimize solids to the lagoon. Figure 17-7 illustrates the process flow for the residuals
streams. Blowdown will be sent to an equalization basin, which will be pumped to a gravity thickener.
Overflow from the gravity thickener will be diverted to the residuals lagoon. The dewatering facilities will
typically be operated only on weekdays. The gravity thickener will store thickened solids over the weekend.
A belt filter press dewatering facility would consist of feed pumps, a dry polymer feed system, and belt filter
presses. Filtrate from the belt filter presses will be sent to the residuals lagoon while the dewatered cakes
will be disposed of off-site. Table 17-9 summarizes equipment sizing for Alternative 3 at the 32 mgd and 38
mgd plant expansion capacity. The gravity thickener was sized for a solids loading rate less than 5 pounds
per day per square foot (Ib/d•SF) and a hydraulic loading rate less than 200 gallons per day per square foot
(gpd/SF).
The residuals management equalization basin and gravity thickener are sized to handle 2050 demands,
projected to be 45 mgd. The equalization basin pumps will need to be upsized to handle additional
blowdown from a third SuperPulsator®. In order to maintain less than 40 hours per week of dewatering
operation at average plant flow and maximum month solids loading, a third belt filter press will need to be
added when average plant flow is approximately 30 mgd. Demand projections anticipate this to occur at
approximately 2050.
The residuals management equipment can be located on the site between the WTP and the residuals
lagoon. Figure 17-8 illustrates a conceptual layout. The existing berm would need to be relocated around
the equipment to provide protection during flood events.
Future average day demand projections with conservation (high and low) were used with the average
solids loading rate to estimate future dry solids volume to the residuals lagoon and leaving the dewatering
facility. Figure 17-9 illustrates the annual dry solids volume assuming 8 percent solids to the lagoon and
20 percent solids leaving the dewatering facility through the future 45 mgd demand. The graphic begins in
Hazen and Sawyer I Residuals Management Facilities 17-16
1

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Initial results have indicated that the chlorine and WET test challenges are resolved with the recent addition
of dechlorination of the backwash waste stream. Therefore, there is not a strong driver for dredging all the
solids in the residuals lagoon. A solution could be to manage the accumulated solids in the lagoon through
more frequent dredging events (e.g., every 1-2 years). More frequent dredging will ensure smaller
quantities of solids must be dredged and disposed of, which may fit better in the solids management plans
for local contractors. NCDEQ has indicated to GUC that dredged material could be located in the area
northwest of the lagoon with drainage back to it. It would not require a permit if it is considered "short term"
maintenance. If GUC staff entered into a long-term contract for solids disposal, then contractors could
provide sufficient permitted sites for solids disposal and the predictability of solids quantity could yield a
more cost-effective solution on a unit basis. A new access road for dredging/dewatering equipment and
for trailers to haul lagoon solids would be required as shown on Figure 16-10.
Satellite images indicate solids buildup in the residual lagoon that has resulted in short-circuiting of the
residuals flow even though the existing lagoon has sufficient capacity (Figure 17-6). It is recommended that
a new outfall in the northeast corner of the lagoon be constructed to minimize the short-circuiting.
Alternating between the two outfalls will provide variation in the residuals flow path through the lagoon to
minimize solids buildup.
The existing 30-inch pipeline from the plant to the residuals lagoon is at capacity with existing residuals and
stormwater streams. For this alternative, a new residuals handling pipeline to convey SuperPulsatore
blowdown to the lagoon is recommended.
Figure 17-6: Alternative 3 Solids Thickening and Dewatering Residuals Process Flow Diagram
Hazen and Sawyer I Residuals Management Facilities 17-15

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
25,000 —
20,000 —
o
c 15,000 —
J
O
cn
-O
O
10,000 — • ----4 F L F 4 4
(4 1 I
, t
- I
- 1
I I 1
5,000 —
2015 2020 2025 2030 2035 2040 2045 2050 2055
Figure 17-5: Alternative 1 Annual Dry Solids Volume to Lagoon Projections (High and Low Average Day Demands)
Hazen and Sawyer I Residuals Management Facilities 17-14

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 17-8: Recommended Solid Storage in Typical Residuals Lagoon
Average Flow I Average Flow/ Average Flow I
Average Solids Average Solids Average Solids
Loading at Future Loading at Future Loading at Future
Plant Capacity of Plant Capacity of Plant Capacity of
Scenario 32 mgd 38 mgd 45 mgd
Flow, mgd 21 25 30
Solids loading, lb/MG 300 300 300
Two year volume, CY 1 33,000 39,000 47,000
Lagoon area, acres 2 3.8 4.4 5.2
8%solids.
2 11 foot depth and 50 percent full.
Hazen and Sawyer I Residuals Management Facilities 17-13
A

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
For the Phase 1 Upgrades PER, four residuals management alternatives were evaluated for the GUC
WTP, as follows:
1. Alternative 1 Use Existing Lagoon—Continue to direct all residuals streams to the existing
lagoon.
2. Alternative 2 Construct New Lagoon—Direct all residuals streams to a new lagoon.
3. Alternative 3 Solids Thickening and Dewatering — Direct sedimentation and SuperPulsator®
blowdown to thickening and dewatering and continue to direct filter backwash and filter-to-
waste to the existing lagoon.
4. Alternative 4 Solids Thickening and Dewatering and Backwash Clarification—Direct
sedimentation and SuperPulsator®blowdown to thickening and dewatering and clarification
for filter backwash and filter-to-waste.
17.3.1 Alternative 1: Use Existing Lagoon
The first residuals management alternative is to continue with current operations and send all residuals to
the existing lagoon. Future average day demand projections with conservation (e.g., high and low) were
used with the average solids loading rate to estimate future solids loading to the residuals lagoon in this
alternative. Figure 17-5 illustrates the annual dry solids volume assuming 8 percent solids in the lagoon
through 2050, when plant demands are projected to be 45 mgd.
The current capacity of the lagoon was evaluated to understand impacts of future solids loading. The GUC
Water Treatment Facilities Master Plan Technical Memorandum#5(HDR, 2012) estimated that the lagoon
was 170,000 cubic yards full of 8 percent solids, or 48 percent full with three feet of freeboard. Average
treated flows for 2013 through 2016 were used with the average solids loading rate (300 lb/MG) to estimate
the additional volume of solids sent to the lagoon since the 2012 Master Plan was developed. It is
estimated that the lagoon now has 210,000 CY of 8 percent solids, or 60 percent full.
New lagoons are typically designed to hold two years of storage at 8 percent solids and 50 percent full.
Table 17-8 summarizes the recommended storage volume for future plant expansion capacities of 32 mgd
and 38 mgd assuming the average solids loading rate. The existing lagoon is currently estimated to be
over 50 percent full; however, the acreage is significantly larger than what is needed for sludge storage.
Additionally, the existing lagoon should provide sufficient detention time for solids settling. Recently, TSS
levels have been well below the NPDES limit and have remained stable. An increase in TSS would indicate
the solids settling capacity of the lagoon has been compromised.
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Table 17-7: Summary of Solids Estimates at Future Plant Capacity
Plant Capac' of 32 mgd Plant Capacity of 38 mjd
Average Flow/ Average Flow/ Average Flow I
Average Flow/ Maximum Average Maximum
Average Solids Month Solids Solids Month Solids
Scenario Loading Loading Loading Loading
Flow, mgd ' 21 21 25 25
Solids loading rate, lb/MG 300 500 300 500
Volume, MG 0.24 0.24 0.29 0.29
Filter backwash 2 %solids 0.015 0.026 0.015 0.025
Weight, lb/day 320 530 380 630
Volume, MG 0.11 1 0.11 0.13 0.13
Filter to waste %solids 0.00 0.00 0.00 0.00
Weight, lb/day 0.00 0.00 0.00 0.00
Volume, MG 0.079 0.079 0.079 0.079
Sedimentation %solids 0.47 0.79 0.30 0.43
blowdown
Weight, lb/day 3,100 5,200 2,000 2,900
+
Volume, MG 0.06 0.06 0.13 0.13
SuperPulsator® % solids 0.53 0.88 0.47 0.83
blowdown 3 -,
Weight, lb/day 2,900 4,800 5,100 9,000
Total Weight, lb/day 6,300 10,500 7,500 12,500
i
'Assume 32 mgd capacity flow is 10 mgd to SuperPulsator°and 11 mgd to sedimentation.Assume 38 mgd capacity
flow is 18 mgd to SuperPulsator°and 7 mgd to sedimentation.
2 Ten filters in service at 32 mgd and twelve filters in service for 38 mgd.
3 One SuperPulsator°in service at 32 mgd and two SuperPulsators®at 38 mgd.
17.3 Residuals Management Alternatives
The current capacity of the lagoon was evaluated to understand impacts of future solids loading. The GUC
Water Treatment Facilities Master Plan Technical Memorandum#5(HDR, 2012) estimated that the lagoon
was 170,000 cubic yards full of 8 percent solids, or 48 percent full with three feet of freeboard. The GUC
Water Treatment Facilities Master Plan concluded that the lagoon had reached its maximum capacity and
alternatives for future residuals management were needed. Complete dredging of the existing lagoon was
considered and determined to be cost prohibitive. The selected alternative from the GUC Water Treatment
Facilities Master Plan was to construct a new lagoon on an adjacent property for future residuals
9 J
management.
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Preliminary Engineering Report
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Residuals mass balance calculations were used to estimate flows and solids loading to the residuals
lagoon and to additional residuals equipment. The future residuals stream will include SuperPulsator®
blowdown and new filter backwash /filter-to waste volume in addition to the existing residuals stream.
Table 17-6 summarizes the assumptions for the SuperPulsator® blowdown operation.
Table 17-6: Summary of SuperPulsator®Blowdown Operations
Parameter Units Design Criteria
Duration per cycle min 1.5
Number of cycles per blowdown ---- 4
Flowrate gpm 450
Blowdown volume per SuperPulsator® gallons 2,700
Blowdown frequency per SuperPulsator® per day 24
Total volume per day with one SuperPulsator® gallons 64,800
Total volume per day with two SuperPulsators® gallons 129,600
Percent of total solids recovery ---- 95%
Assumptions from Tables 17-1 and 17-6 were used for the residuals mass balance calculations for solids
estimates at 32 mgd and 38 mgd plant capacities. Table 17-7 provides a summary of solids production
estimates for at 32 mgd and 38 mgd plant capacities with the selected solids loading scenarios.
Assumptions have been made for the flow split between the existing sedimentation basins and
SuperPulsators®, as these assumptions will impact the solids estimations for each residuals stream.
The instantaneous flowrate of a SuperPulsator®blowdown is 450 gpm, which minimally increases the
maximum instantaneous residuals flowrate from 12,859 gpm to 13,309 gpm. The velocity in the 36-inch
pipe to the lagoon at this flowrate is 4.2 feet per second. The flowrate of a 10-year storm (e.g., 7,400 gpm)
in conjunction with the maximum residuals flowrate increases the velocity through the pipe to 6.5 ft/s. GUC
staff have indicated existing hydraulic challenges with the pipeline to the lagoon. While the new treatment
train should not exacerbate this due to the minor SuperPulsator®blowdown flowrate, the overall residuals
stream combined with a storm indicates that detailed design should include the separation of these two
streams.
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Preliminary Engineering Report
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800 ' ,
' 0 Daily Solids Production
700 -▪--- —7-Day Average -
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—30-Day Average
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Figure 17-4: Solids Production per Million Gallon Treated
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Preliminary Engineering Report
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Figure 17-4 illustrates the daily solids production rates per million gallons treated. The graphic excludes
solids production estimates for days when GUC staff bypassed the pre-sedimentation impoundment, as
this is a rare occurrence and increases solids production. The figure also details the running weekly and
monthly averages for solids production per million gallons treated. Recommended design solids production
rates for future conditions are provided in Table 17-5. The average solids production rate was used to
estimate the existing and future solids volume in the residuals lagoon. The maximum 7-day and 30-day
solids production rates in Figure 17-4 were selected for the max week and max month solids production
rates, respectively. The future average plant flow and maximum month solids production rate were used to
size residuals management equipment for each alternative.
Future maximum plant flow and average solids production will produce less residuals than the future
average flow/maximum month scenario. Dewatering equipment was sized such that operation will be less
than forty hours per week at the average flow and maximum month. Sizing residuals management
equipment to handle extreme solids loading events will result in it being oversized for typical operation. For
extreme events that result in excessive solids loading (such as maximum flow at maximum week
production), Hazen recommends GUC staff send the additional residuals to the residuals lagoon for all
alternatives.
Table 17-5: Recommended Design Solids Production Rates
Scenario Flow Solids Loading
Average solids production Annual Average 300 lb/MG
Maximum month solids production Annual Average 500 lb/MG
Maximum week solids production Annual Average 570 lb/MG
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17.2 Residuals Production Estimates
Solids production estimates for the WTP were developed to assess residuals management alternatives.
WTP operating data from 2012 through 2016 were compiled for raw water treated flow, raw turbidity, alum
dose, polymer dose, PAC dose, and sodium permanganate dose. Literature-based factors, summarized in
Table 17-3, were used to estimate solids produced and collected during sedimentation basin blowdown
and filter backwash. Raw turbidity is used for solids production estimations when historical total suspended
solids is not available. The theoretical solids production factor for raw turbidity is plant-specific. Hazen
selected an initial value based on experience at similar treatment facilities. Hazen recommends that GUC
staff collect TSS and raw turbidity data to confirm the actual ratio of TSS to raw turbidity (Appendix D).
Table 17-3: Theoretical Solids Production Factors
Item I Chemical Theoretical Solids Production (mg/L)
Raw turbidity (reported in NTU) 1.5
Alum dose (reported in mg/L) 1 0.44
Polymer dose (reported in mg/L)2 1.0
PAC dose (reported in mg/L)2 1.0
Permanganate dose (reported in mg/L) 1 0.918
1 AWWA Water Treatment Plant Design.
2 AWWA Water Quality and Treatment.
Daily solids production estimates were developed for daily data from July 1, 2012 through June 30, 2016.
The estimates were normalized to pounds of solids produced per million gallons using the daily raw treated
flow. Table 17-4 summarizes the daily average and maximum solids production rates on an annual basis
from July 2012 through June 2016. Over this four-year period, the daily average solids production was
typically near 300 pounds per million gallons(lb/MG). The daily maximum solids production has varied by
year.
Table 17-4: Annual Average and Maximum Solids Production Rate
July 2012— July 2013— July 2014— July 2015—
June 2013 June 2014 June 2015 June 2016 Average
Daily average solids 267 306 321 306 300
production rate, lb/MG
Daily maximum solids 530 639 669 635 618
production rate, lb/MG
Hazen and Sawyer I Residuals Management Facilities 17-7

Preliminary Engineering Report
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4
• Pass ®Fail
1
cn
cn
46 2
f
z
1 1 IN 1 N
2010 2011 2012 2013 2014 2015 2016 2017
Figure 17-3: Residuals Lagoon Effluent Whole Effluent Toxicity Test Results
Hazen and Sawyer I Residuals Management Facilities 17-6

Preliminary Engineering Report
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50
45
40 - •
35
•
•
30 - -•-
.L F
0
v 25 - •
Tts •
•
20 ` • }� = - - - - -
• • •
15 - -
10 -
5 -
0 i
Sep-11 Oct-12 Nov-13 Dec-14 Jan-16 Mar-17
Figure 17-2: Residuals Lagoon Historical Total Residual Chlorine
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Preliminary Engineering Report
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50 r i
i l
i
45
I •Average •
40 r
• Maximum
0)
35
E
7 30
'o •
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73
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5 • • _ ._ AA • __ •�4 - ••
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Sep-11 Oct-12 Nov-13 Dec-14 Jan-16 Mar-17 Apr-18
Figure 17-1: Residuals Lagoon Historical Effluent Total Suspended Solids
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Preliminary Engineering Report
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Table 17-2: NPDES Permit Requirements for Residuals Lagoon Effluent
Effluent Characteristic Limits Monitoring Frequency
Flow, mgd N/A Continuous
Total suspended solids, mg/L Monthly Average: 30.0
Daily Maximum: 45.0
pH 6.0—9.0 Weekly
Total residual chlorine, pg/L Daily Maximum: 17
Turbidity, NTU
Total aluminum, pg/L
Total iron, pg/L
Total copper, mg/L
Total fluoride, pg/L N/A
Quarterly
Ammonia nitrogen, mg/L
Total phosphorous, mg/L
Total nitrogen, mg/L
Chronic WET testing
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Preliminary Engineering Report
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Table 17-1: Summary of Existing Residuals Operation
Design Criteria Design Criteria at
at Average Flow Maximum Flow
Parameter Units of 13.3 mgd of 22.3 mgd
Duration min 30 30
Flowrate gpm 1,347 2,255
Waste volume per filter gallons 40,423 67,656
Total waste volume per day gallons 67,911 113,662
Total Stream to Lagoon
Total daily residuals volume gallons 318,471 364,222
Maximum residuals instantaneous flowrate 4 gpm 12,859 12,859
10-Year storm flowrate to lagoon gpm 7,400 7,400
Confirmed during 11/3/2016 site visit observation for two Clan-Trac systems in one basin.
2 Assume six sedimentation basins in operation.
3 Assume seven filters in operation.
4 Assume one filter backwash, one filter-to-waste, and one sedimentation basin blowdown.
GUC is authorized to discharge from the southern side of the residuals lagoon into the Tar River via
NPDES Permit number NC0082139. The NPDES permit requires monitoring of effluent characteristics
including flow, metals, ammonia, phosphorous, and WET testing. Additionally, the discharge must meet set
limits for total suspended solids (TSS), pH, and total residual chlorine. Table 17-2 lists the parameters
included in the NPDES permit.
Figure 17-1 illustrates historical TSS for the discharge with respect to the 30 mg/L average and 45 mg/L
maximum limits. The average and maximum TSS levels are less than the NPDES permit limitations and
are not increasing over time, although there have been a few outliers. Historical pH levels are also within
the range set by the NPDES permit.
The NPDES permit limit for total residual chlorine was reduced from 20 pg/L to 17 pg/L in 2015. The
historical total residual chlorine concentrations in exceedance of the permit limit is illustrated in Figure 17-2.
During the five-year period, GUC had 14 samples greater than the chlorine residual limit(out of
226 samples total).
Per the NPDES permit requirements, GUC staff takes a quarterly sample of the lagoon effluent for a WET
test. Figure 17-3 illustrates the number of samples that have passed and failed the test from 2010 to 2017.
In the last 2 years, 28 percent of the WET tests have failed. One possible cause is the occasional high total
residual chlorine concentration that has been measured at the residual lagoon discharge to the Tar River.
In September 2016, GUC staff began to dechlorinate the backwash water and has not had an issue since
(refer to Section 14).
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17. Residuals Management Facilities
The following sections provide a discussion of existing residuals management practices, solids production
estimates, and a residuals management alternatives evaluation for expansion of the GUC WTP.
17.1 Existing Residuals Management
The GUC WTP residuals comprise sedimentation basin blowdown, filter backwash, and filter-to-waste.
Table 17-1 summarizes the typical operations for each of these residuals streams. The residuals waste
streams are all directed to a manhole north of the chemical bulk storage building. Stormwater is also
conveyed to this manhole (refer to Figure 6-10). A 30-inch reinforced concrete pipe runs west from the
manhole into another manhole where the additional stormwater is tied in. A 36-inch reinforced concrete
pipe runs west from this manhole into an outfall at the residuals lagoon. During a 10-year storm an
estimated 7,400 gpm of stormwater is diverted to this pipeline, which is approximately half the flowrate of
the maximum instantaneous residuals stream.
The residuals lagoon is approximately 23 acres with a depth of 14 feet from the lagoon invert to grade. The
top elevations for the manholes supplying the outfall limit the operating level in the lagoon. Operators have
indicated that less than three feet of freeboard in the lagoon will cause overflow of the manholes. Thus, an
operating depth of 11 feet is recommended and has a corresponding volume of approximately
350,000 cubic yards (CY) at a 2.25:1 slope.
Table 17-1: Summary of Existing Residuals Operation
Design Criteria Design Criteria at
at Average Flow Maximum Flow
Parameter Units of 13.3 mgd of 22.3 mgd
Sedimentation Basin Blowdown
Duration min 60 60
Flowrate 1 gpm 220 220
Blowdown volume per basin gallons 13,200 13,200
Frequency per basin per day 1 1
Total blowdown volume per day 2 gallons 79,200 79,200
Percent of total solids recovery ---- 95% 95%
Filter Backwash
Filter run time hr 100 100
Flowrate mgd 15 15
Backwash volume per filter gallons 102,000 102,000
Total backwashes per day 3 ---- 1.7 1.7
Total blowdown volume per day gallons 171,360 171,360
Percent of total solids recovery ---- 5% 5%
Filter-to-Waste
Hazen and Sawyer Residuals Management Facilities 17-1

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Preliminary Engineering Report
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16.2.3 Preliminary Process Design
GAC adsorbers generally take one of two forms: pressure vessels or open bed concrete contactors.
Pressure vessels tend to be more cost effective for plant flows less than 20 mgd. Concrete contactors tend
to be more economical for larger facilities. As such, a layout for concrete GAC beds was considered for
GUC. The design EBCT will depend upon the compound of interest, desired removal rate and the specific
carbon that is selected, among other parameters. For the preliminary facility layout, an EBCT of 15 minutes
was assumed as this is a conservative design for most DBP precursor removal applications.
16.2.4 Planning for Future GAC
Space for a GAC facility has been allocated on the northeast side of the plant site (Figure 6-10). This
facility is sized to provide GAC adsorption capacity for a future plant flow of 45 mgd. The facility has
eighteen filters that are each 20 feet by 21 feet with a media depth of 9 feet. The overall facility dimensions
are 80 feet by 205 feet. Space planning has accounted for a future pipe corridor between the filters, the
GAO facility, and the finished water storage tanks. Additional pumping will be required to overcome the
additional headloss that the GAC adsorbers would introduce to the WTP. The existing clearwell pumps
would need to be modified or replaced to convey the filtered water through the GAC facility to the
clearwells. The proposed clearwell pump station will be designed to accommodate a future GAC facility.
GAC is highly effective in removing compounds from treated water, so finished water chemical feed points
would need to be relocated downstream of the contactors.
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An important aspect of the adsorption process is the quantity of adsorbate that can be adsorbed on the
adsorbent(e.g., GAC). Factors that affect adsorption include pore surface area, pore size distribution, and
surface chemistry. Typical design parameters for post-filter GAC adsorbers include the empty bed contact
time (EBCT), adsorber surface loading rate, and carbon exhaustion time. The EBCT is defined as the tank
volume occupied by the GAC divided by the water flow rate. Typical EBCT values for post-filter GAC
adsorbers for TOC removal range from 10 to 20 minutes. The GAC adsorber surface loading rate is similar
to a filter loading rate. Typical GAC adsorber surface loading rates can vary from 4 to 8 gpm/sf. The carbon
exhaustion time is defined as the time when the GAC adsorber effluent TOC exceeds an operational value
(e.g., breakthrough).
GAC breakthrough curves can be developed for a particular water by running pilot GAC adsorber columns
using full-size GAC media. A typical pilot GAC adsorber column may take three months to one year to
reach breakthrough. A plot of the column effluent TOC versus time is called a breakthrough curve.An
example breakthrough curve is provided in Figure 16-5.
3.0-
2.5—
2.0
rn
V
0
t—
d 1.5—
E
W
F-
U
it 1.0
i—RSSCT 1(10 min Calgon;BMW Plant Strategy)
0.5— --0—RSSCT 2(10 min Norit;BMW Plant Strategy)
---RSSCT 5(10 min Calgon;Pilot Plant Strategy)
—0—RSSCT 6(10 min Norit;Pilot Plant Strategy)
0.0
0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000
Number of Bed Volumes
Figure 16-5: TOC Breakthrough Curves for 10-min EBCT RSSCT Columns
Rapid small-scale column tests (RSSCT)can be conducted in less than four to six weeks. RSSCTs are
also a method for determining breakthrough characteristics. The full-size GAC is ground to a smaller size
and packed in smaller diameter columns to run the RSSCTs.
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16.2 Granular Activated Carbon
16.2.1 Drivers for GAC
GAC adsorption is a physical and chemical process that may be utilized to remove many conventional
compounds from water, such as organics. Removing organics is an effective way of reducing DBPs. GAC
can also be effective in removing emerging and trace contaminants. As regulations begin to focus on new
compounds of interest, GAC may become a more prevalent technology in drinking water treatment. Both
PAC and GAC are used in water treatment applications. However, PAC is often less efficient that GAC for
contaminant adsorption due to required contact times and interference with other chemicals. GAC can be
implemented as either post filtration contactors or by replacing some or all of the conventional filter media
with GAC. Post filter contactors are recommended for GUC due to the limited empty bed contact time
available in the existing filter beds.
16.2.2 Process Overview
GAO is a highly porous material that can remove organic compounds from water via the adsorption
process. Organic compounds present in water are attracted and bound to the surface of the pores in GAC
particles as the water flows through the GAC media. GAO for drinking water is usually manufactured from
bituminous coal, lignite coal, peat, wood or coconut shells. The virgin carbon material is then crushed,
sized, and then activated in high temperature furnaces. The"activation" process creates the highly porous
structure of the GAC particles. The micro pore structure allows for a very high unit surface area (surface
area per unit weight).
Typical physical properties for bituminous GAC are presented in Table 16-3. The pore volume is defined as
the pore volume (in mL) in one gram of GAC. The unit surface area is the amount of surface area (in
square meters) in one gram of GAC. The bulk density is expressed in units of g/cc and is used to estimate
the weight of a certain volume of GAC. Other physical properties include total ash content(which is a
measure of mineral content such as Ca, Mg, Si and Fe), abrasion or hardness number(which is a measure
of the GAC to resist attrition during handling and use), and particle size (expressed in terms of effective
size, uniformity coefficient and mesh number range). Adsorption effectiveness is sometimes characterized
using Iodine Number, Tannin Value, or Molasses Number. These parameters may not always be accurate
in predicting the GAC effectiveness for the removal of a particular organic compound.
Table 16-3: Physical Characteristics of Bituminous GAC
e
Physical Property Range
Pore volume 0.7 to 0.8 mL/g
Unit surface area 900 to 1,050 m2/g
Bulk density 0.45 to 0.50 g/cc
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For planning, a preliminary building footprint was developed for a LPHO UV system and is illustrated in
Figure 6-10. Table 16-2 outlines the preliminary design parameters for the UV facility. For a LPHO system,
the capacity can be increased by adding rows of lamps.
The design UV transmittance (UVT) value was based on historical filtered water UV absorbance data from
the WTP. The design UVT of 85 percent is considered fairly low for a typical drinking water WTP. Low UV
transmittance reduces the efficiency of a UV system, thereby higher lamp power is needed to achieve the
same dose for pathogen inactivation. If UV is implemented in the future, upstream treatment processes
should be evaluated to optimize UVT and UV system design. The design UV dose provides for a 3-log
inactivation of Cryptosporidium at an UVT of 85 percent. This is based on the UV doses required in the
UV Disinfection Guidance Manual(EPA, 2006).
Table 16-2: Process Design for UV Disinfection System
UV Transmittance
Number of UV Capacity per at 253.7 nm Design UV Dose
Design Flow Units UV Unit (minimum) (minimum)
32 mgd 1 duty + 1 standby 32 mgd 85% 12 mJ/cm2
52 mgd 1 duty + 1 standby 52 mgd 85% 12 mJ/cm2
16.1.4 Planning for Future UV Disinfection
Space has been allocated on the site adjacent to the ground storage tank for the UV facility. Figure 6-10
illustrates this facility on the WTP site plan. A piping corridor to and from the UV facility is also allocated on
the site plan. If the UV facility is not part of the initial upgrades to the WTP, tees and plugs would be
provided on the filtered water line to the clearwells to allow for future addition of a UV facility. The clearwell
pump station would need to be modified to accommodate for the additional headloss induced by the UV
reactors. The clearwell pumps would need to be sized to accommodate the additional headloss through the
UV facility (3-4 feet) and to the clearwells. Our proposed clearwell pump station will be designed to
accommodate UV in the future.
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Preliminary Engineering Report
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illustrates an in-line MPHO UV unit. Figure 16-3 illustrates a LPHO UV unit used for larger municipal
applications with flows up to 20 mgd per unit.
A UV facility would be located downstream of the filters as particles and turbidity interfere with the
effectiveness of UV radiation. Figure 16-4 compares the light spectrum produced for both the MP lamps
and the LPHO lamps. The germicidal range is highlighted. UV facilities that utilize medium pressure lamps
tend to have smaller footprints due to the smaller reactor size.
it
s ii• .— e k 1 y.Figure 16-2: In Line UV Unit Figure 16-3: Municipal LPHO UV Unit
(Trojan UVSWIFT) (ITT Wedeco K Series)
Medium Pressure (MP) Lamp Low Pressure Lamp and
Low Pressure/High Output
100 100
90 90
80 80
70 70
w w 60
50 1, 50
E E
ti c 40 040
c
30 30
20 20
10i. . 10
0 0 ,l a a a a
200 250 300 350 400 450 500 550 600 200 250 300 350 400 450 500 550 600
Wavelength[nm] Wavelength[nm]
Figure 16-4: Low Pressure versus Medium Pressure Lamp Output
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Disinfection effectiveness vs. wavelength
Relative
254 nm Low Pressure UV Lamp
effectiveness
(%) Spectral curve of cell
inactivation
DNA Absorption curve
Wavelength (nm)
250 300 350
Figure 16-1: Relative Disinfection Effectiveness versus UV Wavelength
Table 16-1: Summary of Log Inactivation Compared to UV Dose
Log Inactivation
Target
Pathogens 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
UV dose for Cryptosporidium, 1.6 2.5 3.9 5.8 8.5 12 15 22
mJ/cm2
UV dose for Giardia, mJ/cm2 1.5 2.1 3 5.2 7.7 11 15 22
UV dose for Viruses, mJ/cm2 39 58 79 100 121 143 163 186
Reference 40 CFR 141.720(d)(1)and EPA UV Disinfection Guidance Manual for LT2ESWTR, November 2006.
16.1.3 PreliminaryProcess Design
9
UV light is generated by applying a voltage across a gas mixture containing mercury vapor, resulting in a
discharge of photons. The most widely used lamp technologies in the drinking water industry are low-
pressure(LP) and medium-pressure(MP) UV lamps. MP lamps generate polychromatic radiation including
the germicidal UV range(200 nm to 300 nm). LP lamps are more energy efficient than the MP lamps, but
the total UV output per lamp is lower. MP lamps produce 10 to 20 times more germicidal effective UV
output than the LP lamps on a unit length basis. Some LP lamps are categorized as low pressure high
output(LPHO). The mercury filled in these lamps are in the form of amalgam instead of liquid as seen in
the regular LP lamps, which provides higher UV radiation at a low pressure in the lamp. Figure 16-2
Hazen and Sawyer I Future Advanced Treatment 16-2

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
16. Future Advanced Treatment
Future implementation of UV disinfection and GAC adsorption technologies are recommended in Section 2
to address contaminants that may be regulated in the future. These technologies are discussed in more
detail in this section and a conceptual design is presented. Additionally, recommendations for
accommodating these future technologies in near-term upgrades are provided.
16.1 UV Disinfection
16.1.1 Drivers for UV Disinfection
As regulations continue to advance to address emerging contaminants and byproducts of conventional
disinfection techniques, UV disinfection may by a necessary addition to the treatment process. The second
round of Cryptosporidium monitoring is ongoing. If the GUC WTP is classified as Bin 2 or higher, then UV
disinfection may be necessary to meet treatment requirements. While increased ozone doses could help
meet Bin 2 requirements, increased ozone doses may also increase the AOC levels, which presents
concerns for finished water stability and the potential for nitrification in the distribution system. UV
disinfection would provide the necessary inactivation without increasing AOC. Similarly, if GUC elects to
utilize BAF, an increase in HPCs in the filter effluent would be a concern. UV disinfection would provide an
additional barrier to ensure pathogen protection is not compromised by the BAF process. UV disinfection is
a viable alternative to primary disinfection by chlorine because disinfection byproducts are not produced
and the technology is very effective for inactivating pathogens such as Cryptosporidium and Giardia.
16.1.2 Process Overview
UV disinfection is a physical disinfection process as opposed to a chemical disinfection process. UV
disinfection uses electromagnetic energy to inactivate pathogens through the dimerization of thymine
nucleobases on the DNA molecules. This prevents DNA or RNA from replicating. A pathogen that cannot
replicate cannot infect. The germicidal UV irradiation ranges from 200 to 300 nanometers(nm)with the
optimum germicidal effect occurring at a wavelength of 253.7 nm. Figure 16-1 illustrates the relative
disinfection effectiveness versus UV wavelength. UV disinfection does not provide a residual for
disinfection, so it is not suitable for secondary disinfection. Chlorine or chloramines are needed to maintain
a residual in the distribution system.
Little or no disinfection byproducts are formed by the process of UV disinfection at the doses used for
drinking water disinfection. UV is effective for inactivation of bacteria and chemically-resistant pathogens
such as Cryptosporidium and Giardia. UV disinfection is not as effective for inactivation for viruses.
Table 16-1 summarizes the UV dose requirements to achieve various levels of inactivation.
Hazen and Sawyer I Future Advanced Treatment 16-1

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
A second baffling method of inset C-shaped shotcrete walls is recommended for future storage tanks. The
inset C-shaped baffle also minimizes water stagnation within the tanks through its serpentine design. This
baffling option offers improved contact time and reliability (relative to baffle curtains) and can be fabricated
during construction of the tank.
The benefits of baffling can be expressed quantitatively by calculating and comparing disinfection credit
achieved between baffled and non-baffled tanks. An additional CT evaluation was performed comparing
the scenarios under the assumption that the existing tanks had a poor baffling factors of 0.3 and the
improved tanks had (average-superior) baffle factors of 0.6. Descriptions of the baffle factor classifications
are summarized in Table 15-9.
Table 15-9: Summary of Baffling Classifications
Baffling Condition Tio/T Baffling Description
Unbaffled (mixed flow) 0.1 None, agitated basin, very low length/width ratio, high
inlet and outlet flow velocities
Poor 0.3 Single or multiple unbaffled inlets and outlets, no
intrabasin baffles
Average 0.5 Baffled inlet or outlet with some intrabasin baffles
Superior 0.7 Perforated inlet baffle, serpentine or perforated
intrabasin baffles, outlet weir, or perforated launders
Perfect(plug flow) 1.0 Very high length /width ratio(pipeline flow),
perforated inlet, outlet, and intrabasin baffles)
As a result of the higher baffle factors, contact time (Tio) increased significantly in the improved tank
designs. By introducing baffling methods to the ground storage tanks, the required clearwell free chlorine
residual decreased to 0.4 mg/L, 0.5 mg/L, and 0.4 mg/L at future WTP capacities of 32 mgd, 38 mgd, and
45 mgd, respectively. Table 15-10 identifies the disinfection credit achieved using a smaller free chlorine
residual as a result of increased baffling in the existing and new, proposed clearwells.
Table 15-10: Clearwell Free Chlorine Residual Requirements for CT Evaluation
Required Clearwell Free Chlorine Required Clearwell Free Chlorine
WTP Capacity Residual Residual
(mgd) (Without Baffling) (With Baffling)
22.3 0.7 mg/L 0.4 mg/L
32 0.7 mg/L 0.4 mg/L
38 0.8 mg/L 0.5 mg/L
45 0.7 mg/L 0.4 mg/L
Hazen and Sawyer I Clearwell Pumping and Ground Storage 15-11

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 15-7: Summary of Clearwell Disinfection Profile for CT Evaluation
WTP Capacity No. of Giardia Log- Virus Log- Required Clearwell Free
(mgd) Clearwells Inactivation Inactivation Chlorine Residual
22.3 2 3.6 30.6 0.7
32 3 3.6 31.8 0.7
38 3 3.5 30.8 0.8
45 4 3.5 30.1 0.7
15.2.3 Ground Storage Improvements
At increased plant capacities, additional storage volume is necessary to meet free chlorine CT disinfection
requirements Section 5 of this PER documents the storage and operational needs for the additional
storage volume at the plant to accommodate the future demands in the distribution system. Storage
capacity should also be slated to ensure that minimum free chlorine residual may be used to meet
disinfection requirement and avoid DBP formation. Table 15-8 identifies the capacity increments under
consideration and the subsequent ground storage tank quantities and volume. The new ground storage
tanks will be located in the northwest corner of the WTP adjacent to the existing tanks (refer to
Figure 6-10). Additional yard piping is required to tie-in and hydraulically connect the new tanks into the
existing ground storage system. Electrically-operated valves may be utilized to ensure even flow
distribution to the tanks and consistent water quality.
Table 15-8: Ground Storage Tank Additions
WTP Capacity(mgd) Number of Tanks Storage Capacity (MG)
22.3 2 3MG— Each
32 3 3MG— Each
38 3 3MG— Each
45 4 3MG -- Each
The existing tanks do not include baffles that increase free chlorine contact time and mitigate dead zones
that may result in degraded finished water quality. Baffle curtains should be installed in the existing tanks to
provide these benefits. Membrane curtains are commonly implemented as an economical means to
implement baffling in an existing clearwell. These curtains consist of high strength, puncture and tear
resistant fabric approved for contact with potable water. Access hatches located on the exterior domed roof
may be used as an entry point for materials of construction. Baffle curtains are typically anchored to the
tank's ceiling, floor, and sidewalls, which should be carefully coordinated in pre-stressed tank designs to
prevent damage to the pre-stressed wires subsequently compromising the structural integrity of tank. Baffle
curtain installation may be completed during separate tank shutdowns.
Hazen and Sawyer I Clearwell Pumping and Ground Storage 15-10

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
capacity scenario to determine the storage volume and free chlorine residual needed to obtain the required
disinfection credit. The following worse-case scenario assumptions were used based on historical plant
data, as follows:
• Peak flow at the WTP was evaluated at 22.3, 32, 38, and 45 mgd.
• Two clearwells at 22.3 mgd, three clearwells at 32 and 38 mgd, and four clearwells at
45 mgd.
• Tanks operating in parallel.
• CT based on minimum observed temperature of 4°C.
• CT based on maximum observed pre-filter pH of 6.7.
• Clearwell at a minimum water surface elevation of 54.0 feet.
• Contact time does not include piping downstream of storage tanks.
• Post-filter chlorine residual of 0.3 mg/L
• DEQ's Public Water Supply Section approves a 2.5-log credit for Giardia removal and
2.0-log credit for virus removal in plants meeting minimum performance criteria through
conventional treatment processes.
The plant must achieve a minimum of an additional 0.5-log Giardia and 2.0-log virus inactivation credit to
comply with disinfection standards. The target pathogen inactivation goals for Giardia and viruses were set
0.5-log above the minimum requirement to ensure the regulatory requirements are safely met while
mitigating disinfection byproduct formation. The summary of disinfection requirements and goals for the
plant are provided in Table 15-6. Table 15-7 summarizes the free chlorine residual required for adequate
disinfection was calculated to be 0.7 mg/L, 0.8 mg/L, and 0.7 mg/L for future WTP capacities of 32 mgd,
38 mgd, and 45 mgd, respectively.
Table 15-6: Summary of Disinfection Goals for CT Evaluation
Parameter Giardia Viruses
Minimum log-inactivation required 3.0 4.0
Recommended log-inactivation goal 3.5 4.5
Log-inactivation credit through filters 2.5 2.0
Log-inactivation needed via chlorination 1.0 2.5
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Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 15-5: Summary of Existing Ground Storage Tanks
Parameter Units Design Criteria '
Invert elevation feet 28.0
Typical operating range feet 54.0—63.5
Minimum WSE feet 45.8
Inlet/outlet configuration — Separate inlet/outlet
Elevations are reported relative to mean sea level.
15.2.2 Contact Time Evaluation
GUC staff currently relies on ozone for primary disinfection and chloramines for secondary disinfection. In
the event that the ozone system is shutdown, free chlorine is utilized as the primary disinfection strategy.
Chlorine is dosed in the form of sodium hypochlorite in the filter influent and once again in the filtered water
flume prior to the clearwell pump station. A post-filter free chlorine residual sample is also taken in the
filtered water flume before the second chlorine addition. Figure 15-3 illustrates a disinfection schematic with
chemical feed and sample point locations when hypochlorite is used for primary disinfection.
CI
- Qu
(g)
To Finished
�1 Water
® O 0 pumping
filtered O O O Cl)
Filters Water
Flume Ground Storage
Transfer We#
Leggy
O -Segment
Ep -Existing
Chemical Feed
Point
-Existing
Sample Point
Figure 15-3: GUC WTP Schematic of Disinfection Segments with Ozone Out of Service
CT requirements for Giardia lamblia (3-log)and virus(4-log) inactivation are achieved through CT credit
given for conventional treatment processes meeting minimum performance criteria and the CT credit
accumulated through disinfection segments from the filters to the ground storage tanks.Although the
clearwells do not currently contain baffling, the storage volume helps to provide crucial residence time for
primary disinfection operations using free chlorine. An evaluation was completed for each future plant
Hazen and Sawyer I Clearwell Pumping and Ground Storage 15-8

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
At the increased capacity scenarios of 32 mgd to 45 mgd, velocities in the single 30-inch filtered water
transmission line would range from 10.1 ft/s to 14.2 ft/s, respectively. A second 30-inch transmission line
will reduce velocity to a more acceptable range, reduce headloss in the filtered water transmission system,
and subsequently reduce the motor size required for future pump upgrades. The new transmission line
would be provided with a flow meter vault to replicate the metering capabilities provided on the existing
transmission main.
The invasiveness to existing plant operations makes this pumping capacity upgrade option less desirable
than constructing a new pumping facility. Via conversations with GUC staff, the foreseen construction
obstacles require multiple WTP shutdowns. Therefore, Option 2 is not the preferred option.
15.2 Ground Storage
15.2.1 Existing Tanks Evaluation
Finished water at the WTP is currently stored in two 3 MG circular pre-stressed concrete tanks. The
clearwells were constructed with similar above grade designs. Treated water flows from the clearwells,
back to the high service pump station where it is pumped to the distribution system. The clearwell tanks
provide storage volume to meet peak water demands, filter backwash supply, and a supplementary source
of free chlorine contact time to meet primary disinfection requirements in the event the ozone facility is off-
line. Table 15-5 includes a summary of the existing ground storage tank design parameters.
The existing clearwells each have separate 30-inch inlet piping and 36-inch outlet piping configurations,
used to fill and draw from the tanks, respectively. Yard piping is configured for parallel operation of the
storage tanks, although each tank has the capability of being individually isolated. During typical operation,
the tanks may be drawn down to a WSE of 54.0 feet. However, operating procedure is to operate the tanks
above half full (WSE 45.8 feet). The tanks are equipped with 24-inch overflow piping installed at a WSE of
63.5 feet and 24-inch drain pipes, which convey to the residuals lagoon. The clearwells do not currently
contain baffling structures. Proper baffling is used to minimize short-circuiting within the tank and minimize
dead zones.
Table 15-5: Summary of Existing Ground Storage Tanks
Parameter Units Design Criteria 1
Number of tanks ---- 2
Storage volume, each MG 3
Type ---- Circular Domed Pre-stressed Concrete
Baffling ---- None
Inside diameter feet 120
Overflow elevation feet 63.5
Hazen and Sawyer I Clearwell Pumping and Ground Storage 15-7

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
15.1.6 Clearwell Pumping and Transmission Improvements Option 2 — Existing Pump
Station Upgrades
As an alternative, upgrades can be completed on the existing clearwell pump station. The WTP existing
firm capacity is 23.0 mgd. Due to hydraulic limitations and excessive pipeline velocities, a second parallel
30-inch transmission line is needed to alleviate headloss in the filtered water piping between the pump
station and clearwells.
The subsequent pumping options for each future plant capacity scenario are provided in Table 15-4. At
32 mgd, clearwell pump No. 1 and clearwell pump No. 2 should be replaced with two new pumps that
provide 19.5 mgd at the identified head condition. Clearwell pump No. 3 may remain in service. Planning
for a 38 mgd capacity requires three pumps that provide 19 mgd at the identified head condition. Finally,
three pumps providing 22.5 mgd at the identified head condition are required to meet a firm capacity of
45 mgd. For each plant capacity increment, the same pump model with an accompanying variable
frequency drive may be provided for each new pump addition. When increasing the firm pumping capacity
of the existing clearwell pump station, both pump upgrades (e.g., installing vortex suppression) and wet
well improvements and should be vetted with the completion of a physical model study during final design.
Increasing the capacity of the clearwell pump station is coupled with upsizing the individual pump
discharge piping and common header. Individual pump discharge piping and valve upgrades would
accompany individual pump replacement efforts. The existing 30-inch discharge header is currently
insufficient in size to accommodate velocities at increased plant flows and should be replaced with a new
42-inch header. As the header exits the pump station into the yard, the piping splits between the existing
30-inch finished water pipeline and a new parallel 30-inch pipeline. The construction sequencing to
complete the discharge header and pump replacement is estimated to require a minimum of two separate
plant shutdowns.
Table 15-4: Proposed Existing Clearwell Pumping Upgrades at Future Plant Capacity Phases
Number and Clearwell Pump Flow(mgd)
WTP Size of Required No. of
Capacity Clearwell TDH Pump Pump Pump New Existing
(mgd) Pipe (feet) No. 1 No. 2 No. 3 Pumps Pump(s) Kept
32 Two 30 inch 46.6 19.5 19.5 12.5 1 2 Pump No. 3
38 Two 30 inch 49.2 19.0 19.0 19.0 3 None
45 Two 30 inch 52.3 22.5 22.5 22.5 3 None
I Existing pump does not require modifications.
Hazen and Sawyer I Clearwell Pumping and Ground Storage 15-6

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
the capacity output of the existing pump station in tandem operation with the new pump station will be
completely vetted during final design to ensure adequate capacity is provided from the new station. Table
15-3 summarizes the recommended pumping capacities for each WTP capacity phase. The new stand-
alone pump station will be configured with slots for all duty and standby pumps as well as a slot for the
addition of a future pump. Variable speed drives will be equipped to ensure that the pumps can adjust to
match variable filtration rates.
As an alternative for the 32 mgd expansion, GUC may elect to install all three 9 mgd pumps providing
sufficient firm pumping capacity at both pump stations to accommodate an expansion to 38 mgd. This option
provides an additional layer of pumping resiliency allowing the plant's original clearwell pump station to be
shutdown during low plant flow events for future inspection or upgrade efforts. Following expansion of the
filter complex and addition of the new pump station, filters 1 through 4 as well as the existing filter effluent
flume and pump station may be isolated from the filtered water conveyance system via the installed 48-inch
butterfly valve located between the flume and the filtered water piping (i.e. between filters 4 and 5). The
nominal 27 mgd capacity of the new pump station would be sufficient to accommodate the combined filtration
capacity of existing filters 5 through 7 as well as the new four filters planned for the 32 mgd expansion.
Foreseen shutdown events may include, but are not limited to: removal of the backwash supply header
piping, concrete inspection/rehab of the existing wet well, and/or the installation of isolation measures in the
filter effluent flume to more readily accommodate future shut downs of the existing pump station. Although
this option carries a higher capital cost, the third pump slot will be constructed regardless and the option may
provide benefit should the need for the to shut down the existing pump station arise.
A third option for the 32 mgd expansion, which provides a similar level of redundancy is to install two new 12
mgd pumps at the new clearwell pump station, leaving a slot for a third pump.The intent is for the new pumps
to mimic design characteristics of the existing clearwell pumps Nos. 1, 2 and 3. In doing so, the pumps would
be interchangeable between each clearwell pump station and could act as spares if needed. An additional
benefit to this option is that adding a third 12 mgd pump to the new clearwell pump station would provide
over 45 mgd of firm pumping capacity, in the future.
Table 15-3: Proposed New Firm Clearwell Pumping Configurations at Future Plant Capacities
Firm Pumping Supplemental
WTP Capacity Existing Firm Capacity New Clearwell Existing
Capacity Clearwell Pump Requirement Pump Flow No. of New Pump(s)
(mgd) Station (mgd) (mgd) (mgd—Each) 1 Pumps Kept
32 23.0 9.0 9.0 2 All
38 23.0 15.0 15.0 2 All
45 23.0 22.0 11.0 3 All
' Motor sizing of new pumps are to remain low voltage (i.e. less than 300 HP).
Hazen and Sawyer I Clearwell Pumping and Ground Storage 15-5

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
15.1.5 Clearwell Pumping and Transmission Improvements Option 1 — New Clearwell Pump
Station
The primary recommendation for upgrading the WTP's clearwell pumping capacity is to construct a new
(stand-alone) clearwell pump station. The new facility will operate in conjunction with the existing clearwell
pumping system to meet firm pumping requirements for each capacity expansion. To determine the
upgrades associated with the proposed option, the existing clearwell pump performance was evaluated
with the current pumping and transmission infrastructure. The results of the existing pump performance
evaluation are summarized in Table 15-2.
Table 15-2: Existing Firm Clearwell Pumping Capacity
Existing Clearwell Pump Flow(mgd)
Number and Size of Firm Pumping
Filtered Water Piping Lines Pump No. 1 Pump No. 2 Pump No. 3 Capacity (mgd)
One 30 inch 11.5 2 11.5 2 N/A 3 23.0
Ground storage tanks at maximum WSE of 63.5 feet and wet well at a minimum WSE of 23.5 feet.
2 Clearwell pump is operating at full speed. 1170 rpm.
3 Assume clearwell pump No. 3 is not in service during firm pumping conditions.
The capabilities of the existing pump station will remain analogous at future plant capacities assuming no
additional pumping and/or transmission improvements are implemented for the existing infrastructure.
Through hydraulic analysis, clearwell pumps No. 1 and 2 will pump11.5 mgd each, providinga firm
9 Y Y p P 9
capacity of 23.0 mgd. This existing firm pumping capacity is sufficient for the current WTP capacity, but will
need to be supplemented to meet future pumping capacity needs. The existing transmission piping will be
sufficient in the future considering additional pumping capacity will be provided through the new clearwell
pump station.
The new clearwell pumpstation will be located south of the maintenance shopas illustrated in
just
Figure 6-10. A new 54-inch transmission pipe will convey filtered water from the 54-inch filtered water
piping in the new filter gallery extension to the pump station wet well. The pumps will lift and transfer water
through a common 36-inch discharge header. The new transmission line will be provided with a flow meter
vault. Chemical feed points shall be provided downstream of the pumps to provide a point for chloramines
conversion. After the flowmeter vault, the new 36-inch piping will branch and tie into the existing 30-inch
filtered water line just upstream of the ground storage tanks. A new parallel line will also be installed and
will interconnect with existing clearwells and provide for conveyance to advanced treatment processes
(GAC and/or UV) should these processes be implemented in the future. Piping would continue on to a
future (fourth) ground storage tank added for a 45 mgd plant capacity. The proposed transmission piping
route is also illustrated in Figure 6-10.
The new clearwell pump station will house the supplemental pumping capacity required to meet firm
pumping requirements at future WTP flows. The pumping capacity increments required to meet future
treatment plant flows of 32, 38, and 45 mgd are approximately 9, 15, and 22 mgd, respectively. Impacts to
Hazen and Sawyer I Clearwell Pumping and Ground Storage 15-4

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
.N _ • �.
I I
V ,,yy.y
BYeari.Inlet s4-1) l� v
•
oC ob w0 w9 0 0 0 ,0 0 0 60
CWP-1 CWP-2 CWP-3
tow,
Figure 15-2: CFD Model of the Existing CWPS Wet Well at 38 mgd (Plan View Pathline Velocity)
15.1.4 Clearwell Pumping Improvements
Two upgrade options were developed for meeting future clearwell pumping capacity. The two alternatives
include the following improvements:
1. Construct a new clearwell pumping station and transmission line. (Recommended)
o Install three new clearwell pumps (two duty, one standby).
o Install transmission piping from new filter gallery extension to new pump station
and subsequently to the ground storage tanks.
2. Upgrade the existing infrastructure and transmission piping to accommodate increased
capacity.
o Conduct physical model study.
o Improve the wet well design.
o Retrofit or replace pumps.
o Install pump vortex suppression devices.
o Install parallel filtered water piping to the clearwells.
Hazen and Sawyer I Clearwell Pumping and Ground Storage 15-3
� J

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
15.1.3 Clearwell Pump Station Wet Well
As WTP flow increases, the velocity through the wet well weir entrance increases and will result in an
entrance velocity greater than recommended by Hydraulic Institute Standards. Flow momentum is directed
toward the pump bay for clearwell pump No. 3, resulting in high flow recirculation in the wet well to feed the
other two pumps. The CFD modeling illustrating this effect is provided in Figures 15-1 and 15-2. This event
will lead to increased vortex formation in the wet well, which may result in cavitation damage, accelerated
wear of the pump, and excessive noise.
Additionally, the existing wet well configuration does not comply with Hydraulic Institute dimensional
requirements. The existing wet well configuration may compound the undesirable suction approach
conditions in the wet well at higher plant flows. If the intent is to use the existing pump station for flows
greater than 22.3 mgd, a physical model study is recommended during final design to document
problematic wet well features and confirm the reliability of solutions presented to address the unfavorable
suction hydraulic conditions.
Velocity
Sveamime In$ef
R50
45
CWP-1
4 0 `*® •
CWP-2
35
so CWP-3
25 2g�.1
" '. r t
zo
1510
05
0.0
[ft s^-11
Figure 15-1: CFD Model of the Existing CWPS Wet Well at 38 mgd (Isometric Pathline Flow)
Hazen and Sawyer I Clearwell Pumping and Ground Storage 15-2

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
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15. Clearwell Pumping and Ground Storage
15.1 Clearwell Pump Station and Transmission
15.1.1 Existing Facility Evaluation
The clearwell pump station is located in the finished water pump station and shares building space with
backwash and high service pumping systems. The clearwell pump station consists of three vertical turbine
pumps that transfer filter effluent from the pump station wet well to two ground storage tanks (or
clearwells). The pumps are each controlled by variable frequency drives, allowing for pump speed
adjustment to match fluctuating filtration rates. Filtered water flows through a concrete effluent channel and
then passes over a 14.7-foot wide weir wall to the clearwell pump station wet well. The pumps then draw
filtered water from the wet well and discharge into a common 30-inch piping header that is routed to two
3 MG storage tanks operated in parallel. Design data for each of the clearwell pumps is summarized in
Table 15-1.
Table 15-1: Summary of Design Criteria for Clearwell Pumps
Motor Efficiency at
Pump Year Installed Design Flow Design Head Horsepower Design Point
Clearwell 1981 12.0 mgd 52 feet 150 86%
pump No. 1
Clearwell 1981 12.0 mgd 52 feet 150 86%
pump No. 2
Clearwell
pum No. 3 1993 12.0 mgd 52 feet 150 86%
15.1.2 Hydraulic Evaluation
A hydraulic analysis was conducted to evaluate hydraulic constraints at current and future plant capacities.
The list of assumptions used to develop the hydraulic model for the clearwell pump station is as follows:
• Ground storage tank at a maximum WSE of 63.5 feet.
• Wet well at a minimum WSE of 23.5 feet.
• Hazen and Williams coefficient(C factor) of 110.
• Clearwell pumps are operating at full speed.
• One pump out-of-service to simulate a firm capacity scenario.
Hazen and Sawyer I Clearwell Pumping and Ground Storage 15-1

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
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500 -
J _
Q)
c 400 -
0
m
C
U
C
O
U 300 —
a)
ca
O -
O Potential MCL:210 µg/L
▪ 200
>,
c
° 90 degrees F
n 100 - 80 degrees F
5
—70 degrees F
0
Day 0 Day 15 Day 30
Figure 14-12: Chlorate Concentration in Distribution System(1.8 g/L Initial Chlorate Concentration,6.6 mg/L Hypochlorite Dose)
Hazen and Sawyer I Chemical Systems 14-33

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
600 —
en 500 —
c
0 -
c�
L
rt+
w 400 —
0
U -
0
2 300 —
U -
E
0
200 -
-
90 degrees F
0 —80 degrees F
100 —
70 degrees F
0 I i
Day 0 Day 15 Day 30
Figure 14-11: Chlorate Concentration in Distribution System(2.5 gIL Initial Chlorate Concentration, 6.6 mg/L Hypochlorite Dose)
Hazen and Sawyer I Chemical Systems 14-32

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 14-23: Summary of Calcium Thiosulfate Dechlorination Storage and Feed System
Equipment
Parameter Units Design Criteria
Bulk Storage
30-day storage required at 32 mgd gallons 80
Recommended storage at 32 mgd gallons 550—660(two totes)
30-day storage required at 38 mgd gallons 90
Recommended storage at 38 mgd gallons 550—660(two totes)
30-day storage required at 45 mgd gallons 103
Recommended storage at 45 mgd gallons 550—660(two totes)
Chemical Metering Pumps
Maximum feed rate at 32 mgd gph 6
Recommended pumps at 32 mgd ---- 2 (duty/standby)
Maximum feed rate at 38 mgd gph 6
Recommended pumps at 38 mgd ---- 2(duty/standby)
Recommended pump type Diaphragm
14.11 Biologically Active Filter Chemicals
The potential conversion to BAF would necessitate the addition of sodium hydroxide and hydrogen
peroxide to the filter influent. The targeted pH for finished water would remain the same; therefore, the total
plant sodium hydroxide dose would not increase with the addition of BAF. The existing chemical feed
storage areas will be sufficient for BAF at the future 45 mgd demand. An additional metering pump would
provide sodium hydroxide to the filters.
The Ozone-BAF pilot indicated that peroxide could have some benefit for controlling biological growth and
excessive headloss. Hydrogen peroxide is not currently used at the plant. The new rapid mix chemical feed
area has space allocated for hydrogen peroxide storage and feed should a BAF conversion occur. The
containment is sufficient for chemical metering pumps and a 6,000-gallon tank. This storage volume can
accept a full delivery load and can meet peroxide needs through the future 45 mgd demand. Figure 14-8
depicts the new chemical feed area plan.
Hazen and Sawyer I Chemical Systems 14-31

Preliminary Engineering Report
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Greenville Utilities Commission
summarizes the sodium bisulfite storage and feed equipment capacities and requirements. Table 14-23
summarizes the calcium thiosulfate storage and feed equipment capacities and requirements should a
longer reaction time become more feasible.
The advantages of sodium bisulfite over calcium thiosulfate are the cost and the shorter detention time,
which is needed for this application. The main challenges with sodium bisulfite are that it off-gasses sulfur
dioxide and freezes at 43°F. The recommended design minimizes these challenges with double vacuum
vents on the totes and storage indoors. Carrying water could be added on the metering pump discharge if
there are freezing concerns once it leaves the room. If calcium thiosulfate is used, it will need to be overfed
to account for the detention time restrictions. Over-dosing of calcium thiosulfate may produce milky-colored
suspected solids and may promote thiobacillus bacterial growth.
The sodium bisulfite storage and feed system will be located in the new chemical bulk storage building.
The two totes will be sufficient to meet the future 45 mgd demand. Sodium bisulfite bulk storage tanks
typically require specialized venting precautions due to sulfur dioxide off gassing. This is not a concern with
totes, which are equipped with double vacuum vents. New piping will be installed from the totes, to the
metering pumps, and to the backwash waste application point. The chemical metering pumps will be
sufficiently sized for the future 45 mgd demand unless the backwash flow rate were to increase in the
future. A preliminary floor plan of the new chemical bulk storage building is shown on Figures 14-4 and
14-7.
Table 14-22: Summary of Sodium Bisulfite Dechlorination Storage and Feed System
Equipment
Parameter Units Design Criteria
Bulk Storage
30-day storage required at 32 mgd gallons 332
Recommended storage at 32 mgd gallons 550—660(two totes)
30-day storage required at 38 mgd gallons 393
Recommended storage at 38 mgd gallons 550—660(two totes)
30-day storage required at 45 mgd gallons 453
Recommended storage at 45 mgd gallons 550—660(two totes)
Chemical Metering Pumps
Maximum feed rate at 32 mgd gph 26
Recommended pumps at 32 mgd ---- 2(duty/standby)
Maximum feed rate at 38 mgd gph 26
Recommended pumps at 38 mgd ---- 2 (duty/standby)
Recommended pump type Diaphragm
Hazen and Sawyer I Chemical Systems 14-30

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
After several months of operation, manganese levels began to increase on the filters. Subsequently, GUC
relocated the dechlorination feed point to the backwash waste stream. Since the implementation of
dechlorination, fourth quarter 2016 WET test passed and chlorine residuals have been below the NPDES
limit.
GUC staff has requested a permanent system for dechlorination, assuming it continues to provide a
resolution to the lagoon outfall challenges. The two most common alternatives for dechlorination are
calcium thiosulfate and sodium bisulfite. Table 14-21 summarizes the design criteria used for sizing the
dechlorination equipment for the future design capacities of 32 mgd, 38 mgd, and 45 mgd for both
chemicals.
Table 14-21: Summary of Dechlorination Storage and Feed System Design Criteria
Parameter Units Design Criteria
Backwash
32-mgd WTP average daily backwash volume 1 gallons 270,000
38-mgd WTP daily average backwash volume 2 gallons 320,000
45-mgd WTP daily average backwash volume 2 gallons 370,000
Wash rate mgd 15
Chlorine Residual to Lagoon
Initial concentration mg/L 4.5
Target concentration mg/L 1.0
Residual to neutralize mg/L 3.5
Calcium Thiosulfate 3
Reaction time sec 300
Dose per mg/L chlorine residual mg/L 0.53
Total dose 4 mg/L 3.7
Sodium Bisulfite 3
Reaction time sec 15
Dose per mg/L chlorine residual mg/L 1.5
Total dose' mg/L 10.5
Assume 11 filters, 100 hour filter run time. 102,000 gallons per backwash.
2 Assume 13 filters. 100 hour filter run time. 102.000 gallons per backwash.
3 Water Environment Research Foundation, Disinfection of Wastewater Effluent—Comparison of Alternative
Technologies. 2008.
4 Safety factor of 2.
GUC staff is currently feeding close to 30 mg/L of calcium thiosulfate to counteract the longer reaction time.
The backwash waste line discharges into a manhole with other waste streams, thus the detention time is
short. As a result, sodium bisulfite would be a more optimal dechlorination chemical. Table 14-22
Hazen and Sawyer Chemical Systems 14-29

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
GUC staff have measured chlorate levels in the bulk hypochlorite storage upon delivery and dilution. The
initial concentrations ranged from 1.1 g/L to 2.5 g/L with an average chlorate concentration of 1.8 g/L. The
American Water Works Association Hypochlorite Assessment Model was used to model chlorate
concentrations in the distribution system based on historical chlorine doses and varying temperatures in
the chemical bulk storage building. Figure 14-11 illustrates chlorate formation with the initial maximum
chlorate concentration and an average hypochlorite dose. At day zero, the chlorate concentration of the
bulk hypochlorite would exceed the potential 210 pg/L MCL in the distribution system. Figure 14-12
illustrates chlorate formation with the initial average chlorate concentration and an average hypochlorite
dose.
Chlorate concentrations in the bulk hypochlorite storage would need to address the anticipated MCL. The
following options are recommended if a chlorate is regulated as a MCL:
• Condition bulk storage space to max temperature of 75°F— It is estimated that
temperatures in warmer months will exceed 95°F. An initial budgetary cost for conditioning
the bulk storage space is $150,000.
• Increase dilution in warmer weather—GUC staff currently dilutes hypochlorite to
7.5 percent. Dilution to 5 percent would further delay chlorate degradation in the bulk
solution.
• Specify maximum chlorate level— In sodium hypochlorite vendor agreements, specify a
maximum chlorate level that can be delivered onsite.
• More frequent deliveries in warmer weather—As the AWWA models suggest, dosing bulk
hypochlorite prior to 15 days of storage will minimize potential chlorate exceedances.
Additional and more costly measures may be implemented if the chlorate MCL cannot be met with the
aforementioned recommendations. GUC staff could install chillers to reduce the temperature of the bulk
hypochlorite and minimize chlorate formation, which is anticipated to be cost prohibitive. Another option is
to switch to onsite hypochlorite generation in lieu of sodium hypochlorite deliveries. A typical system would
consist of three 10,000 gallon tanks(e.g., one day of storage at maximum flow, average dose), two
2,000-pound per day units, a 60 ton brine tank, and ancillary equipment. A conceptual footprint indicates
that the system could fit inside the existing footprint of the chemical bulk storage. A budgetary cost
estimate for the onsite system is$1.5 million.
14.10 Dechlorination
The lagoon discharge has failed 50 percent of the quarterly Whole Effluent Toxicity (WET) tests in 2015
and 2016. The residual chlorine limit for the lagoon outfall National Pollutant Discharge Elimination System
(NPDES) permit has been exceeded several times. In September 2016, GUC staff began dechlorinating
the backwash water supply with 30 percent calcium thiosulfate to minimize chlorine residual in the lagoon.
Hazen and Sawyer I Chemical Systems 14-28

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 14-20: Summary of Sodium Hypochlorite Storage and Feed System Equipment
Parameter Units Design Criteria
Recommended storage at 38 mgd gallons 71,508
30-day storage required at 45 mgd gallons 75,900
Recommended number of tanks at 45 mgd ---- Existing+4 new tanks
Capacity of new tanks, each gallons 12,000
Recommended storage at 45 mgd gallons 83,508
Tank material ---- HDPE
Chemical Metering Pumps
Number of existing metering pumps ---- 4
Capacity of existing metering pumps gph 106
Existing New
Application points Existing New clearwell clearwell
filters filters influent influent
channel channel
Maximum feed rate at 32 mgd gph 108 49 110 50
Recommended pumps at 32 mgd Keep Keep Three(2 duty/1
existing existing standby)
Maximum feed rate at 38 mgd gph 108 97 110 100
Recommended pumps at 38 mgd Keep Keep Three(2 duty/1
existing existing standby)
Recommended pump type ---- Diaphragm
Several improvements are required for the new hypochlorite system. Bulk storage of the sodium
hypochlorite system will remain in the existing chemical bulk storage building. The existing alum and
caustic bulk storage tanks will be demolished and removed, which will provide sufficient space for bulk
storage to meet the future 45 mgd demand. Recirculation pumps are recommended for the existing and
new tanks to promote thorough mixing after dilution. New piping will be installed to the new filter application
point and the new clearwell influent channel. Some chemical metering pumps will need to be replaced to
meet the higher feed rates necessary for the future 45 mgd demand. Floor plans of the existing chemical
bulk storage building and existing chemical feed area are illustrated in Figures 14-4 through 14-7 and 14-2
through 14-3, respectively.
14.9.2 Chlorate Formation
Section 2.3 of this report provides a detailed summary of perchlorate and chlorate regulatory issues.
Chlorate formation commonly occurs in drinking water facilities that use bulk hypochlorite or OSG
hypochlorite. EPA has announced a chlorate health reference level of 210 pg/L. Chlorate is likely to be
regulated in the future, so the potential for chlorate formation in GUC's bulk hypochlorite storage was
assessed in this analysis.
Hazen and Sawyer I Chemical Systems 14-27

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
14.9 Sodium Hypochlorite
14.9.1 Storage and Feed
Sodium hypochlorite is delivered to the plant at a concentration of 15 percent and diluted to 7.5 percent.
The bulk storage tanks are located in the existing bulk chemical storage building in a shared containment
area with alum and caustic. Chemical metering pumps located in the existing chemical feed area feed
hypochlorite to the filters and the clearwell influent channel for disinfection. Carrying water is currently
used. A secondary application point is used on the suction of the finished water pumps during free chlorine
burnout events.
The capacity of the existing hypochlorite equipment has been evaluated for the future design flows of
32 mgd, 38 mgd, and 45 mgd. Table 14-19 summarizes the doses used for sizing of the hypochlorite
equipment. The hypochlorite storage and feed system is not equipped with a day tank. GUC staff indicated
this would continue to be acceptable for future operations. Table 14-20 summarizes the storage and feed
equipment capacities and requirements.
Table 14-19: Summary of Sodium Hypochlorite Dose
Dose Maximum Average Minimum
Filter dose, as sodium hypochlorite, 9.1 2.1 0.4
mg/L 1
Clearwell influent channel dose, as 9.2 4.5 1.6
sodium hypochlorite, mg/L
Historical data set between January 2007 and September 2016.
Table 14-20: Summary of Sodium Hypochlorite Storage and Feed System Equipment
Parameter Units Design Criteria
Bulk Storage
Number of existing bulk storage tanks ---- 3
Total capacity of existing tanks gallons 35,508
30-day storage required at 32 mgd gallons 53,200
Recommended number of tanks at 32 mgd ---- Existing+2 new tanks
Capacity of new tanks, each gallons 12,000
Recommended storage at 32 mgd gallons 59,508
30-day storage required at 38 mgd gallons 63,300
Recommended number of tanks at 38 mgd ---- Existing+3 new tanks
Capacity of new tanks, each gallons 12,000
Hazen and Sawyer I Chemical Systems 14-26

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Hazen PROCESS FLOW DIAGRAM FOR
CHEMICAL FEED POINTS

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 14-18: Summary of Sodium Hydroxide Storage and Feed System Equipment
Parameter Units Design Criteria
24-hour storage at 32 mgd gallons 934 133
Recommended storage at 32 mgd gallons Keep existing 300
24-hour storage at 38 mgd gallons 1,053 265
Recommended storage at 38 mgd gallons Keep existing 300
Tank material --- HDPE
Chemical Metering Pumps
Number of existing metering pumps ---- 4
Capacity of existing metering pumps gph 106
Existing New
Application points Existing SuperP clearwell clearwell
vault rapid mix influent influent
channel channel
Maximum feed rate at 32 mgd gph 111 50 85 40
Recommended pumps at 32 mgd Keep Relocate Three(2 duty/1
existing 2 existing standby)
Maximum feed rate at 38 mgd gph 111 100 85 110
Recommended pumps at 38 mgd Keep Relocate Three (2 duty/1
existing 2 existing standby)
Recommended pump type ---- Diaphragm
Caustic is fed by gravity to the existing day tank.
2 Secondary application point(filters and finished water pump suction)will not have a dedicated metering pump;
during these events the pumps dedicated for the primary application points will be utilized.
Bulk storage of the caustic system will be relocated to a new chemical bulk storage building. The existing
bulk storage tanks will be taken out of service and replaced. The new caustic bulk storage has sufficient
capacity to meet the future 45 mgd demand. A large bubble air mixing system is recommended to promote
complete mixing after dilution. The building will have a mechanical room with space for the air compressor.
The existing chemical feed area is shown on Figures 14-2 and 14-3. Preliminary floor plans of the new
chemical bulk storage building and new chemical feed area are shown on Figures 14-4 through 14-8.
Caustic will be transferred to two locations. The first location is the new chemical feed area for the
SuperPulsator® rapid mix application point. The second location is the existing chemical feed area for both
the existing rapid mix and clearwell influent channel application points. New piping will be installed from the
transfer pumps to the existing and new chemical feed areas, and to the new rapid mix application point.
New piping will also be installed from the existing chemical feed area to the new clearwell influent channel
application point. The new chemical feed area will have sufficient space for a larger day tank in the future
to meet the future 45 mgd demand. Two existing feed pumps can be relocated to this area for the new
SuperPulsator®rapid mix feed point. To meet the future 45 mgd demand, some chemical metering pumps
will need to be replaced in the future for higher feed rates.
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Preliminary Engineering Report
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Table 14-17: Summary of Sodium Hydroxide Dose
Dose Maximum Average Minimum
Rapid mix dose, as sodium hydroxide, 37.2 8.3 0.4
mg/L '
Clearwell influent channel dose, as 27.1 12.5 3.6
sodium hydroxide, mg/L
Historical data set between January 2007 and September 2016.
Table 14-18: Summary of Sodium Hydroxide Storage and Feed System Equipment
Parameter Units Design Criteria
Bulk Storage
Number of existing bulk storage tanks ---- 3
Total capacity of existing tanks gallons 32,237
30-day storage required at 32 mgd gallons 41,900
Recommended storage at 32 mgd, per tank gallons 15,000
Recommended number of new tanks ---- 3
Total storage at 32 mgd gallons 45,000
30-day storage required at 38 mgd gallons 49,900
Recommended storage at 38 mgd, per tank gallons 15,000
Recommended number of new tanks ---- 4
Total storage at 38 mgd gallons 60,000
30-day storage required at 45 mgd gallons 60,000
Recommended storage at 45 mgd, per tank gallons 15,000
Recommended number of new tanks ---- 4
Total storage at 45 mgd gallons 60,000
Tank material -- Steel
Transfer Pumps
Number of existing pumps ---- 0'
Recommended number of pumps ---- Three(2 duty, 1 standby)
Day Storage
Number of existing day tanks ---- 1
Capacity of existing day tank gallons 1,050
Existing vault and
Application points2 ---- clearwell influent SuperP rapid mix
channels
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Preliminary Engineering Report
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Table 14-16: Summary of Polymer Storage and Feed System Equipment
Parameter Units Design Criteria
Recommended pumps at 32 mgd Keep existing Two(duty/standby)
Maximum feed rate at 38 mgd gph 87 78
Recommended pumps at 38 mgd Keep existing Two(duty/standby)
Recommended pump type Diaphragm
Assume 50 lb buckets.
2 DP500 can handle up to 20 lb/hr at 0.75%emulsion.
3 Secondary application points(Flocculator 1, Flocculator 7, and filters)will not have a dedicated metering pump;
during these events the pumps dedicated for the primary application points will be utilized.
14.8 Sodium Hydroxide
Sodium hydroxide (caustic) is delivered to the plant at a concentration of 50 percent and diluted to
25 percent(using air mixing)with an effective density of 2.61 pounds of caustic per gallon. The existing
bulk storage tanks are located in the existing bulk chemical storage building in a shared containment area
with alum and sodium hypochlorite. Caustic flows by gravity to a day tank located in the existing chemical
feed area. Chemical metering pumps feed caustic to the influent vault downstream of the pre-
sedimentation impoundment and the clearwell influent channel. Carrying water is currently used.
Secondary application points include the filters and the finished water pump suction.
The capacity of the existing caustic equipment has been evaluated for the future design capacities of
32 mgd, 38 mgd, and 45 mgd. Table 14-17 summarizes the dose used for sizing of the caustic equipment
for the future capacity at each application point. Table 14-18 summarizes the storage and feed equipment
capacities and requirements for caustic.
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Preliminary Engineering Report
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Table 14-15: Summary of Polymer Dose
Dose Maximum Average Minimum
Rapid mix dose, mg/L 1 0.30 0.10 0.01
Historical data set between January 2007 and September 2016.
The new polymer feed system will be located in the new chemical feed area to include space allocated for
dry bucket storage. The dry polymer feed system will have sufficient capacity to meet 2050 demands,
although the metering pumps must be replaced to meet the higher feed rates. New piping will be installed
from the dry polymer feed system to the new chemical metering pumps and to the new rapid mix
application point. Additional piping will be installed for the secondary application point at the new filters;
however, a new metering pump will not be dedicated to this application point. A preliminary floor plan of the
new chemical feed area is illustrated in Figure 14-8. A floor plan of the existing chemical feed area is
shown on Figures 14-2 and 14-3.
Table 14-16: Summary of Polymer Storage and Feed System Equipment
Parameter Units Design Criteria
Bulk Storage
30-day storage required at 32 mgd lb 390
Recommended storage at 32 mgd ---- 8 buckets'
30-day storage required at 38 mgd lb 463
Recommended storage at 38 mgd ---- 10 buckets
30-day storage required at 45 mgd lb 555
Recommended storage at 45 mgd ---- 12 buckets
Dry Polymer Feed System
Capacity of existingDP500 system lb/hr 10.7 at 4%emulsion 2
P Y Y
Application points3 ---- Flocculator 4 SuperP rapid mix
Maximum feed rate at 32 mgd lb/hr 2.01 0.90
Recommended system at 32 mgd gallons Keep existing Additional DP500
DP500
Maximum feed rate at 38 mgd lb/hr 2.01 1.81
Recommended system at 38 mgd gallons Keep existing Additional DP500
DP500
Chemical Metering Pumps
Number of existing metering pumps ---- 3
Capacity of existing metering pumps gph 106
Application points3 ---- Flocculator 4 SuperP rapid mix
Maximum feed rate at 32 mgd gph 87 39
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Preliminary Engineering Report
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Table 14-14: Summary of Sodium Permanganate Storage and Feed System Equipment
Parameter Units Design Criteria
Application points Existing train raw New train raw water
water influent vault influent vault
Maximum feed rate at 32 mgd gph 12.6 5.68
Recommended pumps at 32 mgd --- Keep existing 1
Maximum feed rate at 38 mgd gph 12.6 11.4
Recommended pumps at 38 mgd ---- Keep existing 1
Recommended pump type ---- Diaphragm
The permanganate system is currently equipped with two metering pumps. A third metering pump will act
as the standby for the existing and new raw water train application points. The existing permanganate
storage and feed system is sufficient to handle the future 45 mgd demand. The new metering pump
capacity will have to be increased to meet additional plant needs in the event of a raw water quality issue. It
is recommended that the primary permanganate application point remain downstream of the pre-
sedimentation impoundment. The existing application point will have to be relocated on the raw water line
to accommodate the berm for the new pre-sedimentation impoundment, if constructed. An additional
application point will be added to the new treatment train raw water line. The new application point will
require new piping from the storage and feed room.
GUC staff has indicated a preference for a new contactor upstream of the new rapid mix. The existing p raw
water ozone contactor has a contact time of approximately 4 minutes at maximum plant capacity. The
additional contact time has provided the necessary manganese removal the GUC staff targets. To provide
a similar contact time, the new contactor should be sized for approximately 28,000 gallons per 10 mgd
treated. Additional contactor cells may be constructed as SuperPulsators®are added to the new treatment
train. The permanganate contactor is located on the site plan in Section 9. A floor plan of the existing
chemical feed area is illustrated in Figures 14-9 and 14-10.
14.7 Polymer
A dry polymer, SELfloc 1770, is delivered to the plant in buckets. The storage and feed system are located
in the existing chemical feed area. Dry polymer is fed into the hopper of a dry polymer feed system
(DP500)where it is mixed with water to form a polymer emulsion. Chemical metering pumps feed the
polymer emulsion to Flocculator 4 for coagulation aid. Carrying water is currently used. A secondary
application point is located at the filters but is infrequently used.
The capacity of the existing polymer equipment has been evaluated for the future design flow of 32 mgd,
38 mgd, and 45 mgd. Table 14-15 summarizes the dosage used for sizing of the polymer equipment for
future capacity. Table 14-16 summarizes the storage and feed equipment capacities and requirements for
polymer.
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Preliminary Engineering Report
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14.6 Sodium Permanganate
Sodium permanganate (permanganate) is delivered to the plant at a concentration of 20 percent with an
effective density of 1.93 pounds of sodium permanganate per gallon. The bulk storage tank is located in
the existing bulk chemical storage building in the permanganate storage and feed room. Chemical
metering pumps feed permanganate to the influent vault downstream of the pre-sedimentation
impoundment for manganese control, as needed. Carrying water is currently used. GUC staff currently use
the raw water ozone contactor upstream of rapid mix to provide additional contact time for the
permanganate. There is the potential for an additional feed point at the vault upstream of the pre-
sedimentation impoundment; however, the piping for this additional feed point currently does not extend
beyond the storage and feed room.
The capacity of the existing sodium permanganate equipment has been evaluated for the future plant flows
of 32 mgd, 38 mgd, and 45 mgd. Table 14-13 provides a summary of the dose used for sizing of the
sodium permanganate equipment for the future capacity. The permanganate storage and feed system is
not equipped with a day tank. GUC staff indicated this would continue to be acceptable for future
operations. Table 14-14 summarizes the storage and feed equipment capacities and requirements.
Table 14-13: Summary of Sodium Permanganate Dose
Dose Maximum Average Minimum
Influent vault dose, as sodium 3.20 0.40 0.05
permanganate, mg/L '
'Historical data set between January 2007 and September 2016.
Table 14-14: Summary of Sodium Permanganate Storage and Feed System Equipment
Parameter Units Design Criteria
Bulk Storage
Number of existing bulk storage tanks ---- 1
Total capacity of existing tanks gallons 10,000
30-day storage required at 32 mgd gallons 1,300
Recommended storage at 32 mgd ---- Keep existing
30-day storage required at 38 mgd gallons 1,500
Recommended storage at 38 mgd gallons Keep existing
30-day storage required at 45 mgd gallons 1,800
Recommended storage at 45 mgd gallons Keep existing
Chemical Metering ete Pumps
9
Number of existing metering pumps ---- 2
Capacity of existing metering pumps gph 32.3
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Preliminary Engineering Report
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14.5 Powdered Activated Carbon
PAC is delivered to the plant into a silo located south of the existing bulk chemical storage building. An
auger screw feeds PAC into a wetting cone attached to an eductor. Motive water conveys PAC to the
second flocculator for taste and odor control, as needed. The capacity of the existing PAC equipment has
been evaluated for the future design capacities of 32 mgd and 38 mgd. The dosage used for sizing of the
PAC equipment for the future capacity is summarized in Table 14-11. The storage and feed equipment
capacities and requirements for PAC are summarized in Table 14-12.
Table 14-11: Summary of Powdered Activated Carbon Dose
Dose Maximum Average Minimum
Influent vault dose, as dry product, mg/L ' 18-6 7.5 2.5
'Historical data set between January 2007 and September 2016
The existing PAC storage and feed system is sufficient to handle the future 45 mgd demand. In the event
that water quality conditions warranted additional contact time, GUC could mobilize a temporary PAC feed
system to accommodate short term treatment challenges.
Table 14-12: Summary of Powdered Activated Carbon Storage and Feed System Equipment
Parameter Units Design Criteria
Bulk Storage
Number of Existing Silos ---- 1
Total capacity of existing silo CF 2,500
30-day storage required at 32 mgd CF 1,400'
Recommended storage at 32 mgd ---- Keep existing
30-day storage required at 38 mgd CF 1,600
Recommended storage at 38 mgd ---- Keep existing
30-day storage required at 45 mgd CF 1,900 1
Recommended storage at 45 mgd ---- Keep existing
Auger Screw 2
Existing auger low range CF/hr 0.03—3.00
Existing auger high range CF/hr 0.12—12.00
Application points ---- Raw water
Maximum feed rate at 32 mgd CF/hr 6.95
Recommended auger screw at 32 mgd ---- Keep existing
Maximum feed rate at 38 mgd CF/hr 9.10
Recommended auger screw at 38 mgd ---- Keep existing
'Assume 30 lb/CF for delivered PAC.
2 Existing eductor can handle both low and high range. GUC has another auger screw with a low range of
0.10- 10.00 CF/hr and a high range of 0.40—40.00 CF/hr. This may be necessary if density of PAC is closer to
20 lb/CF.
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Preliminary Engineering Report
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acceptable for future operations. Table 14-10 summarizes the storage and feed equipment capacities and
requirements for orthophosphate.
Bulk storage of the liquid orthophosphate system will be located in the new chemical bulk storage building.
The existing batch storage tank could be re-purposed as a day tank. The new orthophosphate bulk storage
tank will be sized to handle a full load and to meet the future 45 mgd demand. New piping will be installed
from the new bulk tank to the existing chemical feed area and pumps. The existing chemical metering
pumps are sufficiently sized for the future 45 mgd demand, however an additional pump and application
point will need to be added for the new clearwell influent channel. New piping will be installed from the
existing chemical feed area to the new clearwell influent channel application point. A preliminary floor plan
of the new chemical bulk storage building and a floor plan of the existing chemical feed area are provided
on Figures 14-4 through 14-7 and 14-2 through 14-3, respectively.
Table 14-10: Summary of Orthophosphate Storage and Feed System Equipment
Parameter Units Design Criteria
Bulk Storage
Number of existing batch tanks ---- 1
Total capacity of existing tanks, each gallons 400
30-day storage required at 32 mgd gallons 1,700
Recommended storage at 32 mgd gallons 6,000
Number of tanks at 32 mgd ---- 1
30-day storage required at 38 mgd gallons 2,000
Recommended storage at 38 mgd gallons 6,000
Number of tanks at 38 mgd ---- 1
30-day storage required at 45 mgd gallons 2,400
Recommended storage at 45 mgd gallons 6,000
Number of tanks at 45 mgd ---- 1
Tank material --- HDPE
Chemical Metering Pumps
Number of existing metering pumps ---- 2
Capacity of existing metering pumps gph 35
Application points Existing clearwell New clearwell
influent channel influent channel
Maximum feed rate at 32 mgd gph 6.6 2.9
Recommended pumps at 32 mgd ---- Keep existing 1 1
Maximum feed rate at 38 mgd gph 6.6 5.9
Recommended pumps at 38 mgd ---- Keep existing 1 1
Recommended pump type ---- Diaphragm
1 Assuming liquid orthophosphate selection is compatible with metering pump components.
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Preliminary Engineering Report
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An additional chemical feed pump and application point will be needed for the new clearwell influent
channel. New piping will be installed from the existing chemical feed area to the new clearwell influent
channel application point. Aside from this, the fluoride storage and feed system is sufficient to handle the
38 mgd plant expansion. GUC staff has indicated that the existing bulk storage tank must be drawn down
significantly prior to accepting a full load. The recommended 6,000 gallon storage tank will hold at least
1,000 gallons of fluoride in addition to a full delivery volume. The new bulk storage tank would also be
sufficiently sized to meet the future 45 mgd demand. The day tank will need to be replaced to meet the
future 45 mgd demand.
The existing bulk storage room has approximately 3,500 gallons of containment. A volume of 7,000 gallons
is needed for a full tank volume and 20 minutes of sprinkler water. Hazen recommends demolishing the
west wall of the fluoride room and constructing a new wall running east-to-west alongside the hypochlorite
chemical trench. This modification will expand the size of the bulk fluoride room and provide sufficient
containment. The floor plan of the expanded fluoride bulk storage room and the existing chemical feed
area are shown on Figures 14-9 through 14-10 and 14-2 through 14-3, respectively.
14.4 Orthophosphate
Orthophosphate, a corrosion inhibitor, is delivered to the plant in fifty-pound buckets at 100 percent
orthophosphate. Dry chemical is batch mixed with 100 gallons of water in the batch tank located in the
existing chemical feed area. A chemical metering pump feeds the batched orthophosphate to the clearwell
influent channel for corrosion inhibition. Carrying water is currently used. The capacity of the existing
orthophosphate equipment has been evaluated for the future design capacities of 32 mgd, 38 mgd, and
45 mgd. Table 14-9 summarizes the dosage used for sizing of the orthophosphate equipment for the future
capacity.
Table 14-9: Summary of Orthophosphate Dose
Dose Maximum Average Minimum
Clearwell influent channel dose, 34% 3.2 1.2 0.6
phosphate, mg/L 1'2
Historical data set between January 2007 and September 2016.
2 GUC indicated dose was as dry product, however chemical supplier would not provide %phosphate specifications.
This assumption allows for conservation in design.
GUC staff currently batch orthophosphate in a 400 gallon tank approximately twice per day. Batching
operations would be more frequent and a burden to WTP operators for an expanded WTP. A bulk liquid
orthophosphate system is recommended to eliminate the need for manual batching operations. Bulk
storage sizing for a 100 percent liquid orthophosphate was evaluated, assuming a 34 percent as
phosphate strength and an effective density of 3.90 pound of phosphate per gallon. The orthophosphate
storage and feed system is not equipped with a day tank. GUC staff indicated this would continue to be
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Preliminary Engineering Report
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Table 14-7: Summary of Fluoride Dose
Dose Maximum Average Minimum
Clearwell influent channel dose, as 1.0 2 1.0 0.7
fluoride ion, mg/L 1
Historical data set between January 2007 and September 2016.
2 Historical maximum is 1.4 mg/L. Equipment sizing is for 1.0 mg/L per North Carolina Administrative Code
15A.18C.1406.
Table 14-8: Summary of Fluoride Storage and Feed System Equipment
Parameter Units Design Criteria
Bulk Storage
Number of existing bulk storage tanks ---- 1
Total capacity of existing tanks gallons 4,972
30-day storage required at 32 mgd gallons 2,900
Recommended storage at 32 mgd gallons 6,000
Number of tanks at 32 mgd ---- 1
30-day storage required at 38 mgd gallons 3,400
Recommended storage at 38 mgd gallons 6,000
30-day storage required at 45 mgd gallons 4,100
Recommended storage at 45 mgd gallons 6,000
Tank material --- HDPE
Day Storage
Number of existing day tanks ---- 1
Capacity of existing day tanks,each gallons 90
24-hour storage at 32 mgd gallons 72
Recommended storage at 32 mgd gallons Keep existing
24-hour storage at 38 mgd gallons 85
Recommended storage at 38 mgd gallons Keep existing
Chemical Metering Pumps
Number of existing metering pumps ---- 2
Capacity of existing metering pumps gpd 190
Application points Existing clearwell New clearwell
influent channel influent channel
Maximum feed rate at 32 mgd gpd 100 45
Recommended pumps at 32 mgd ---- Keep existing 1
Maximum feed rate at 38 mgd gpd 100 90
Recommended pumps at 38 mgd ---- Keep existing 1
Recommended pump type ---- Peristaltic
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Preliminary Engineering Report
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Table 14-6: Summary of Ammonia Storage and Feed System Equipment
Parameter Units Design Criteria
Bulk Storage
Number of existing bulk storage tanks ---- 1
Total capacity of existing tanks gallons 8,000
30-day storage required at 32 mgd gallons 3,800
Recommended storage at 32 mgd ---- Keep existing
30-day storage required at 38 mgd gallons 4,500
Recommended storage at 38 mgd ---- Keep existing
30-day storage required at 45 mgd gallons 5,400
Recommended storage at 45 mgd ---- Keep existing
Chemical Metering Pumps
Number of existing metering pumps ---- 3
Capacity of existing metering pumps gph 16
Application points' Existing clearwell New clearwell pump
pump discharge discharge
Maximum feed rate at 32 mgd gph 7.9 3.5
Recommended pumps at 32 mgd ---- Keep existing Keep existing
Maximum feed rate at 38 mgd gph 7.9 7.1
Recommended pumps at 38 mgd ---- Keep existing Keep existing
'Secondary application point(finished water pump suction)will not have a dedicated metering pump;during these
events the pumps dedicated for the primary application points will be utilized.
14.3 Hydrofluosilicic Acid (Fluoride)
Hydrofluosilicic acid (fluoride) is delivered to the plant at a concentration of 23 percent with an effective
density of 1.86 pounds of fluoride ion per gallon. The bulk storage tank is located in the existing bulk
chemical storage building in the fluoride storage and feed room. Fluoride flows by gravity to a day tank
located in the existing chemical feed area. Chemical metering pumps feed fluoride to the clearwell influent
channel for fluoridation. Carrying water is currently used.
The capacity of the existing fluoride equipment has been evaluated for the future plant expansions to
32 mgd, 38 mgd, and 45 mgd. Table 14-7 lists the dosage used for sizing of the fluoride equipment for the
future capacity. Table 14-8 summarizes the storage and feed equipment capacities and requirements for
fluoride.
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Bulk alum storage will be relocated to a new chemical bulk storage building. The existing bulk storage
tanks will be taken out of service and replaced. The new alum storage room will have sufficient space for
an additional 16,000 gallon fiberglass reinforced plastic (FRP) tank to meet the future 45 mgd demand.
Alum will be transferred to two locations: 1)the existing chemical feed area for the existing rapid mix
application point and 2) the new chemical feed area for the SuperPulsator®rapid mix application point.
New piping will be required between the transfer pumps to the existing and new chemical feed area, and to
the new rapid mix application point. To meet the future 45 mgd demand, the new chemical feed area will
have sufficient space for a larger day tank in the future. Chemical metering pumps will need to be replaced
for higher feed rates. The existing chemical feed area is provided on Figures 14-2 and 14-3. Preliminary
floor plans of the new chemical bulk storage building and new chemical feed area are shown on Figures
14-4 through 14-8, respectively.
14.2 Ammonium Hydroxide
Ammonium hydroxide (ammonia) is delivered to the plant at a concentration of 19 percent with an effective
density of 1.21 pounds of ammonia per gallon. The bulk storage tank is located in the existing bulk
chemical storage building in the ammonia storage and feed room. Chemical metering pumps feed
ammonia to the clearwell pump discharge for disinfection. A secondary application point on the suction of
the finished water pumps is used during free chlorine burnout events.
Sizing of the existing ammonia equipment has been evaluated for the future design capacities of 32 mgd
38 mgd. and 45 mgd. Table 14-5 summarizes the dosage used for sizing of the ammonia equipment for the
future capacity.
Table 14-5: Summary of Ammonia Dose
Dose Maximum Average Minimum
Clearwell pump discharge dose, as 1.5 1.0 0.7
ammonia, mg/L 1
Historical data set between January 2007 and September 2016.
The existing ammonia storage and feed system is not equipped with a day tank. GUC staff indicated this
would continue to be acceptable for future operations. Table 14-6 summarizes the storage and feed
equipment capacities and requirements for ammonia. The existing bulk storage tank and chemical feed
pumps are sufficiently sized to meet the future 45 mgd demand. However, an additional feed point will
need to be provided for ammonia feed at the new clearwell pump station discharge. New piping will be
installed from the ammonia storage and feed system to the new clearwell influent channel application point.
The existing floor plan of the ammonia storage and feed system is shown on Figure 14-9.
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Preliminary Engineering Report
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Table 14-4: Summary of Alum Storage and Feed System Equipment
Parameter Units Design Criteria
Bulk Storage
Number of existing bulk storage tanks ---- 2
Total capacity of existing tanks gallons 23,946
30-day storage required at 32 mgd gallons 65,500
Number of tanks at 32 mgd ---- 4
Recommended storage at 32 mgd, per tank gallons 16,000
Total storage at 32 mgd gallons 64,000
30-day storage required at 38 mgd gallons 77,800
Number of tanks at 38 mgd gallons 5
Recommended storage at 38 mgd, per tank gallons 16,000
Total storage at 38 mgd gallons 80,000
30-day storage required at 45 mgd gallons 92,100
Number of tanks at 45 mgd gallons 6
Recommended storage at 45 mgd, per tank gallons 16,000
Total storage at 45 mgd gallons 96,000
Tank material --- FRP
Transfer Pumps
Number of existing transfer pumps 1 ---- 0
Number of proposed transfer pumps ---- Three(2 duty, 1 standby)
Day Storage
Number of existing day tanks ---- 1
Capacity of existing day tank gallons 850
Application points ---- Existing rapid mix SuperP rapid mix
24-hour storage at 32 mgd gallons 759 341
Recommended storage at 32 mgd gallons Keep existing 700
24-hour storage at 38 mgd gallons 759 682
Recommended storage at 38 mgd gallons Keep existing 700
Tank material ---- --- HDPE
Chemical Metering Pumps
Number of existing metering pumps ---- 3(diaphragm)
Capacity of existing metering pumps gph 106
Application points --- Existing rapid mix SuperP rapid mix
Maximum feed rate at 32 mgd gph 195 90
Recommended pumps at 32 mgd 2 ---- Keep existing Two(duty/standby)
Maximum feed rate at 38 mgd gph 195 175
Recommended pumps at 38 mgd 2 ---- Keep existing Two(duty/standby)
Recommended pump type -- -- diaphragm
Alum is currently fed by gravity to the existing day tank
2 GUC utilizes two pumps at max feed rate demands. New pumps will be sized for one pump at maximum feed rate
demands.
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Preliminary Engineering Report
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Table 14-2: Chemical Storage and Feed System Design Flow Rates
Capacity Maximum Average
age Minimum
Future Expansion Alternative 1 —32 mgd
Plant flow rate, mgd 32.0 21.00 5.00
Existing rapid mix capacity, mgd 22.3 --- 5.00
SuperPulsator® rapid mix capacity, mgd 10.0 -- 5.00
Future Expansion Alternative 2—38 mgd
Plant flow rate 38.0 25.00 5.00
Existing rapid mix capacity, mgd 22.3 --- 5.00
SuperPulsator®rapid mix capacity, mgd 20.0 --- 5.00
14.1 Aluminum Sulfate
Aluminum sulfate (alum) is delivered to the plant at a concentration of 48 percent and with an effective
density of 5.34 pounds of alum per gallon (lb/gal). Existing bulk storage tanks are located in the existing
bulk chemical storage building in a shared containment area with sodium hypochlorite and sodium
hydroxide. Alum is fed by gravity to a day tank located in the existing chemical feed area. Chemical
metering pumps feed alum to the rapid mix vault for coagulation. Carrying water is currently used. The
existing alum equipment has been evaluated for future plant design capacities of 32 mgd, 38 mgd, and
45 mgd. The dosage used for sizing of the alum equipment for the future capacity is provided in Table 14-3.
Table 14-3: Summary of Alum Dose
Dose Maximum Average Minimum
Rapid mix alum dose, as alum, mg/L 1 134.1 43.7 21.9
Historical data set between January September and Se tember 2016.
GUC staff requested that alum bulk storage capacity be more robust than typical storage design due to
occasional high alum demands. Hazen assessed bulk storage at maximum flow, average dose and
average flow, and the 95th percentile dose. The maximum flow, average dose requires more volume and
was therefore used for bulk storage sizing. Table 14-4 summarizes the storage and feed equipment
capacities and requirements for alum.
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Preliminary Engineering Report
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14. Chemical Systems
The chemical system evaluation reviewed the existing chemical storage and feed systems and
requirements for the future plant expansion. Table 14-1 summarizes the chemicals currently used at the
WTP and the current application points. The application points are illustrated in Figure 14-1. Table 14-2
provides a summary of the chemical feed system design flow rates used in this assessment for the existing
plant capacity of 22.3 mgd and immediate expansion alternatives of 32 mgd and 38 mgd. For each plant
expansion alternative, the maximum, average, and minimum design criteria are provided.
Other design criteria for the chemical feed systems were selected based on input from GUC staff. Bulk
storage tanks were designed for 30-day storage (as required by NC Administrative Code Title 15A,
Subchapter 18C) at average flow and average dose, except where noted for alum. Day tank storage,
where needed, was designed for maximum flow and average dose. Per GUC staff, day tank storage was
sized to handle two fills per day. New day tanks were sized for the 38 mgd plant expansion regardless of
the alternative selected. Chemical metering pumps were sized based on maximum flow and maximum
dose. Any new buried chemical piping between facilities will be encased in duct banks. All chemical
storage areas were also assessed for the future 45 mgd plant capacity.
Table 14-1: Summary of Existing Plant Chemicals and Application Points
Chemical Application Points
Aluminum sulfate (alum) Rapid mix
Ammonium hydroxide Clearwell pump discharge
Finished water pump suction (secondary)
Hydrofluosilicic acid Clearwell influent channel
Orthophosphate Clearwell influent channel
Powdered activated carbon Flocculator 4
Sodium permanganate Influent vault
Polymer Flocculator 4
Flocculators 1 and 7 (secondary)
Filters (secondary)
Sodium hydroxide Influent vault
Filter influent channel (secondary)
Clearwell influent channel
Finished water pump suction (secondary)
Sodium hypochlorite Filters
Clearwell influent channel
Finished water pump suction (secondary)
Hazen and Sawyer I Chemical Systems 14-1

t
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s PHASE 1 WTP IMPROVEMENTS
8 GREENVILLE UTILITIES COMMISSION
PLAN-EL 27.00
FIGURE 13-10
Hazen NEW BACKWASH SUPPLY HEADER
0

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
• Cold and warm water temperature conditions of 40° and 90°F, respectively.
• Leopold (Xylem) IMS capfilter underdrains with 1 foot of sand and upto 4 feet of GAC filter
P ( Y )
media (for a biofiltration configuration).
Table 13-8: Second Backwash Pump Preliminary Design Details
Parameter Units Design Criteria
Pump type ---- Can, vertical turbine
Capacity gpm 10,880
Total dynamic head feet 43
Motor size HP 200
Speed rpm 1,180
Given the additional footprint and capital costs of adding a second backwash pump combined with the
proven reliability of the existing backwash pump over the service life of the facility, GUC staff indicated a
preference for Option 1. This preference requires attention to another concern identified with the existing
backwash system. Currently, there exists a potential threat of damage to filter underdrain equipment and
loss of filter media due to excessive pressures in the backwash supply through the back-up system.
Precise pressure control is unavailable through the manual butterfly valve that isolates the high-service
pump discharge header from the backwash pump discharge piping. Operating pressures in the high-
service pump discharge header are typically an order of magnitude greater than that in the backwash
supply system. Filter underdrains cannot withstand these higher pressures, likely sustaining catastrophic
damage if exposed to such pressures. Likewise, these high pressures excessively expand the filter media,
resultingin carryover to the backwash troughs, and eventual loss through the backwash waste collection
rY 9 9
system. Replacement of the manual butterfly valve with a pressure-reducing type valve(PRV) providing
precise control of the downstream supply pressure to the backwash system, significantly reduces these
concerns (refer to Figure 13-10). Tied into the WTP's existing SCADA system, the PRV provides GUC staff
with reliable, remote control of the back-up backwash system in the event the backwash pump is
unavailable for service.
Hazen and Sawyer I Biological Filtration Analysis 13-19

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
The recommendation is replacement of the backwash header with a new line located above grade in the
filter pipe gallery (refer to Figure 13-10). The existing backwash supply header may be isolated and
abandoned in place or removed if so desired. However, removal efforts are also invasive to plant
operations during construction and warrants a detailed construction sequence plan to mitigate GUC
exposure to plant production limitations. Vetting of these three configurations for the WTP are summarized
in Table 13-7.
Modifications to the existing backwash supply system to furnish washwater to the new filter complex
provides an opportunity to evaluate the level of reliability and redundancy offered by the existing
configuration. In the absence of a dedicated backwash supply tank, typical backwash supply configurations
implemented at water treatment facilities include the following:
• Option 1 —One backwash pump with distribution system back-up (e.g., current
configuration utilized by GUC staff).
• Option 2—Two backwash pumps—one duty, one stand-by.
• Option 3—Two backwash pumps with a distribution system back-up.
Table 13-7: Backwash Supply System Alternatives—Design Considerations
Option Design Considerations
1 • Rely on distribution system back-up for extended time period with a pump failure.
• No additional building footprint or additional yard piping required.
• Status-quo for GUC staff.
• Modify distribution system back-up to increase reliability.
2 • Forego modifications to the distribution system back-up.
• Additional building footprint required for new pump.
• Additional yard piping required to provide backwash supply to new pump.
• Moving existing backwash pump to new building footprint provides a future high-
service pump slot.
3 • Modify distribution system back-up to increase reliability.
• Additional building footprint required for new pump.
• Additional yard piping required to provide backwash supply to new pump.
• Moving existing backwash pump to new building footprint provides a future high-
service pump slot.
Preliminary design of a second backwash pump considered the location of a new clearwell pump station to
the west of the new filter complex. Table 13-8 provides preliminary design details of the second backwash
pump. The design further utilized the following assumptions:
• The ground storage tanks operate between WSE 45.75 feet(half full) and 63.50 feet(full).
• High and low wash backwash rates of approximately 20 and 5 gpm/SF, respectively.
Hazen and Sawyer I Biological Filtration Analysis 13-18

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 13-6: Summary of Design Criteria for Existing Backwash System
Parameter Units Design Criteria
Flow control size inches 18
Flow control type — Butterfly
Backup System High Service Pressure—Butterfly Valve
Isolation
One concern identified with the existing backwash system is the current condition of the submerged
backwash header. Two separate inspection events identified significant corrosion of the header and signs
of failure of the pipe coating system. The first inspection, performed in August 2013, provided the following
findings:
• At rust removal locations, metal loss measured between 0.0625 inches to 0.25 inches.
• Severe corrosion of flanged piping hardware.
• Non-intact coating system.
A second inspection, performed in September 2015, yielded these subsequent results:
• Ultrasonic thickness measurements identified the wall thickness of the pipe ranges
between 0.75 inches to 0.80 inches.
• Caliper pit measurements of approximately 0.13 inches.
• Heavy corrosion on all hardware, tee fittings, and piping located above with typical water
surface in the flume.
The backwash supply inspection report prepared in September 2015 is included as a supplement to this
PER (Appendix C). Nominal wall thickness for AWWA C115 flanged ductile iron pipe is approximately
0.47 inches, considerably less than the results obtained from the ultrasonic testing. Record drawings were
unavailable to confirm the wall thickness of the piping provided for this particular installation. Given this
uncertainty, the challenges of further condition monitoring efforts(e.g., plant shutdown), and the criticality of
this process piping, the recommendation is to move forward with the replacement of this piping. This
replacement effort includes replacement of the concrete-encased portion of the header located underneath
the filter gallery extension serving Filters 5 to 7. Replacement within the flume presents the following
challenges:
• Highly disruptive to plant operations and a significant construction sequencing challenge.
• Relatively inaccessible area likely resulting in premium construction costs.
• Corrosive environment persists following replacement.
Hazen and Sawyer I Biological Filtration Analysis 13-17

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
allocated on the site plan to allow for an intermediate pump station in the event that GUC elects to
implement complete conversion to BAF in the future as described in Option 1.
Of the chemical enhancement strategies, the results suggest that either caustic or peroxide can improve
UFRVs with minimal water quality impacts. Either chemical enhancement strategy is recommended. Dual
chemical addition with either caustic or peroxide will not provide greater operational improvement over the
most advantageous chemical alone, so therefore dual chemical addition is not recommended.
13.4 Filter Backwash System Evaluation and Proposed Upgrades
The existing filter backwash system consists of a single, can-type vertical turbine pump that conveys
backwash water to each individual filter along a 24-inch ductile iron pipe (DIP) header. Backwash supply
water comes from the plant's two 3 MG ground storage tanks feeding the suction side of the backwash
pump. A combination Venturi flow meter and modulating butterfly valve control the flow output of the
constant speed pump achieving different wash rates at the filter. Construction of the backwash supply
header serving the first four filters operates in a submerged environment within the filtered water flume.
The remaining header, encapsulated in concrete, runs underneath the foundation slab of the filter gallery
serving the remaining three filters at the plant. A butterfly valve, located between the high-service pump
discharge header and the backwash pump discharge, serves as the backup to the pump. In the event the
backwash pump is unavailable, the plant staff isolate the backwash pump from service, and slowly open
the butterfly valve to provide washwater off the high-service discharge header. Table 13-6 summarizes the
design conditions of the existing filter backwash system.
Table 13-6: Summary of Design Criteria for Existing Backwash System
Parameter Units Design Criteria
Backwash Pump
Quantity --- 1
Type --- Can-type, vertical turbine
Design capacity gpm 10,000
Design discharge pressure feet 43
Motor size HP 150
Speed rpm 1,170
Drive type --- Constant speed
Backwash Piping
Header size inches 24
Individual filter pipe size inches 20
Flow Control
Flow meter size inches 18
Flow meter type --- Venturi
Hazen and Sawyer I Biological Filtration Analysis 13-16

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
100% 32
Z 95% 4
a — 30
cc 90% -
0 — 28 0
o 85% - I. J 1. J L - - 0
- 2
0
c 80% r , — 26 c
o 0 U 75% — 24 v
-a 2
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65% 1 -
— 20
z 60% 1 —.—Biotic Filter Z
55% , —0—Abiotic Filter — 18
50% 16
0 12 24 36 48 60 72 84 96 108 120
Filter Runtime (hrs)
Figure 13-9: Net Water Production
13.3.4 Option 4—Abiotic Filtration Without an Intermediate Pump Station
The fourth filtration alternative for consideration at the WTP involves operation of both the existing and the
proposed filters in an abiotic mode. This option eliminates the need for an intermediate pump station. New
filters with deeper filter tubs provide additional hydraulic head and subsequent longer filter run times.
Otherwise, the existing filter configuration remains unchanged providing GUC staff with a level of familiarity
regarding operations and anticipated filter performance.
13.3.5 Recommended Filtration Configuration
While the results of the Ozone-BAF pilot indicate some water quality benefits with BAF, the costs
associated with implementing BAF for all filters at the WTP make this option less appealing. Therefore,
Hazen recommends Option 4—Abiotic Filtration without an Intermediate Pump Station. It is recommend
that the current expansion be designed and constructed so that GUC staff has the option to convert to
biofiltration if treatment requirements change in the future.
Biofiltration would assist GUC staff in improving water stability and reducing disinfection byproducts.
However, implementing biofiltration would come at the cost of decreased filter run times and increased
capital and operating costs. Water quality improvements are marginal, not substantial, and not required to
meet current regulations. Therefore, it is recommended GUC continue with abiotic filtration. Space is
Hazen and Sawyer I Biological Filtration Analysis 13-15

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
13.3.3 Option 3 —Convert to BAF Without an Intermediate Pump Station
Without an intermediate pump station, the available hydraulic head is 5.5 feet over the existing filters.
Unfortunately, altering the hydraulic control point in the upstream ozonated water channel to gain driving
head over the existing filters is not feasible due to the hydraulic constraints of the existing upstream
process infrastructure. As an alternative, construction of the new filters with additional depth may provide
the recommended driving head for BAF operations and serve to offset the reduced filter run times and
additional operation and maintenance (O&M) costs anticipated across the unmodified existing filters.
Additionally, biological operation of the existing filter configuration reduces filtered water production at the
Y WTP plant.
Currently, the achieves filter run times of nearly 100 hours in the abiotic filters. Based on unit
filter run volume data from full-scale BAF demonstration Filter 6, and from the pilot study data collected on
the filter column with supplemental caustic addition, it is anticipated that full-scale run times for the existing
filters would be between 24 and 58 hours. The reduced filter run times affect net water production (NWP).
Figure 13-9 illustrates the NWP calculated for BAF and abiotic filters at a plant capacity of 32 mgd. NWP
was estimated for abiotic and BAF filters at a WTP capacity of 32 mgd, taking into account the following:
• Potable water used for backwashing (approximately 102,000 gallons per wash) and
filter-to-waste operations (approximately 30 minutes at maximum filter loading rate).
• Lost filter production if a filter reaches terminal headloss or maximum turbidity limits while
another filter is already in backwash mode.
• A minimum four-hour rest period after each backwash of a biological filter.
An additional filter, beyond that needed for firm filtration capacity, could offset the reduction in NWP and
maintain the reliable filtration capacity of the WTP. Table 13-5 presents predicted NWP values for 32 mgd
and 38 mgd plant capacities with and without the additional filter considering a complete conversion to BAF
at the WTP. Section 19 presents the capital cost implications of the additional filter to ensure the reliable
capacity of the WTP.
Table 13-5: Reliable BAF Capacities Based on Net Water Production
Reliable Capacity Reliable Capacity
Nominal Plant Capacity with N+1 Filters with N+2 Filters
32 mgd 28.7- 31.7 mgd 35 mgd
38 mgd 33.9-37.5 mgd 41 mgd
Hazen and Sawyer I Biological Filtration Analysis 13-14

/ SKYLIGHT,FOR
/ EQUIPMENT EXTRACTION
30"ARV,TYP
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PHASE 1 WTP IMPROVEMENTS
GREENVILLE UTILITIES COMMISSION
Hazen�r�p„ FIGURE 13-8
INTERMEDIATE PUMP STATION
SECTIONS

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GREENVILLE UTILITIES COMMISSION
Hazen TOP PLAN FIGURE 13-7
3i3r'=r-o° INTERMEDIATE PUMP STATION
PLAN

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
13.3 Filter Configuration Alternatives
An ozone BAF pilot was conducted in summer and fall 2016. The goal of this study was to determine the
feasible application of BAF at the WTP, evaluating different configurations, chemical feed strategies, and
GAC media designs to enhance BAF performance. Section 12 of this PER provides additional discussion
of the BAF piloting effort. Several filter alternatives including BAF, abiotic filters and a combination of both
were evaluated. Table 13-4 summarizes the alternative filter configurations considered for the WTP.
Table 13-4: Filtration Configuration Options
Intermediate Pump
Option Existing Filters Proposed Filters Station?
1 Convert to BAF BAF Yes
2 Remain abiotic BAF No
3 Convert to BAF BAF No
4 Remain abiotic Abiotic No
13.3.1 Option 1 — Biologically Active Filters With an Intermediate Pump Station
Biologically active filters typically require more driving hydraulic head than abiotic filters due to higher
headloss accumulation rates through the media bed. An intermediate pump station between the
intermediate ozone and the filtration processes would provide additional driving head through both the
existing and the proposed filters. Successful BAF installations commonly provide 8 to 10 feet of driving
hydraulic head to reduce the impact of biological growth on filter run times observed in the filters. Pumping
between intermediate ozone and the filtration processes allows the plant to recover head that was provided
originally before implementation of the intermediate ozone process. Figures 13-7 and 13-8 illustrate plan
and section views, respectively, of the conceptual intermediate pump station designed for the WTP to
support the conversion to BAF. The conceptual design consists of a vertical turbine pump, wet well
configuration with accommodations for four pumps (two duty, one standby, and one future). Discharge from
the pump station conveys ozonated water to the existing and new filter influent flumes.
13.3.2 Option 2— Hybrid BAF Without an Intermediate Pump Station
A conceptual hybrid BAF treatment technique considered operation of the existing filters in an abiotic mode
while operating the new filters biologically. The new filter design consists of deeper filter tubs to provide at
least 8 feet of driving head above the media without the need for an intermediate pump station. Although
the water quality benefit represents only a fraction of that anticipated with a full plant conversion to BAF,
the hybrid approach provides a potential cost savings with the elimination of the intermediate pump station
while maintaining the abiotic operation of the existing filters.
Hazen and Sawyer I Biological Filtration Analysis 13-11

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PARTIAL YARD PIPING PLAN GREENVILLE UTILITIES COMMISSION
FIGURE 13-1
Hazen SITE LAYOUT OF PROPOSED
r. FACILITY EXPANSION

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Preliminary sizing of the filter gallery piping accommodates ultimate build-out capacity of 45 mgd.
Table 13-3 summarizes the different filter process piping applications, preliminary sizing, and design
considerations. Ozonated water is conveyed to each new filter via a common, overhead filter influent flume.
The flume design eliminates the need for a substantial pipe support system and mitigates headloss. An air
gap is provided on the backwash waste line in order to prevent cross-contamination and to prevent an
overflow of the waste piping system into the filter gallery.
The proposed filter gallery aligns with the existing filter gallery to allow for easy access to the expanded
filtration facilities and tie-in to the existing filtration piping systems. The upper level of the filter complex will
provide a covered space for operator access to the filters. The upper level will be connected to the
operating floor of the existing filter building. A canopy will be provided over the filters whether they are
abiotic or BAF. This will allow for future conversion to BAF and provide protection against extensive algae
growth on the filters.
Table 13-3: Proposed Filter Gallery Piping
Diameter
Service (inches) Material
Filter influent header 48 x 72 Concrete
Filter influent branches 24 DIP or CS
Backwash waste header 36 DIP or CS
Backwash waste branches 24 DIP or CS
Filter effluent/ BWS 20 DIP or CS
Filter effluent/ FTW 16 DIP or CS
Filter effluent header 54 DIP or CS
Filter to Waste header 16 DIP or CS
Backwash supply header 24 DIP or CS
Air scour 10 Stainless steel
' Utilizing carbon steel in the filter gallery may reduce the cost of the filter gallery piping.
Hazen and Sawyer I Filters 13-4

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 13-2: Proposed Filter Basis of Design
Design Criteria, Design Criteria, Design Criteria,
Parameter Units Flow of 32 mgd Flow of 38 mgd Flow of 45 mgd
Approximate available feet 10 10 10
driving head
Approximate freeboard feet 3.5 3.5 3.5
Trough width inches 21.5 21.5 21.5
Trough quantity per --- 3 3 3
filter cell
Washwater system ---- Air and water Air and water Air and water
BAF/GAC Filters
Media configuration ---- 48" GAC, 12" Sand 48" GAC, 12" Sand 48" GAC, 12" Sand
Uniformity coefficient --- Sand: <_ 1.40 Sand: s 1.40 Sand: <_ 1.40
GAC: <_ 1.40 GAC: <_ 1.40 GAC: <_ 1.40
Effective size mm Sand: 0.45—0.55 Sand: 0.45—0.55 Sand: 0.45—0.55
GAC: 1.3— 1.5 GAC: 1.3— 1.5 GAC: 1.3— 1.5
Distance between top inches 40 40 40
of media and
underside of trough
Approximate available feet 8 8 8
driving head
Approximate freeboard feet 3.5 3.5 3.5
Trough width inches 21.5 21.5 21.5
Trough quantity per ---- 3 3 3
filter cell
Washwater system ---- Air and water Air and water Air and water
Figure 13-1 summarizes the preliminary site layout of the filters for each of the capacity increments up to
45 mgd. Figures 13-2 through 13-6 provide preliminary plan and section views for new filter complex. It
should be noted that the section view of the filters indicates a filter tub depth adequate to accommodate
installation of 4 feet of GAC media plus the recommended hydraulic head over the filter for successful BAF
operations. Filter tub depth could be decreased from that shown with implementation of new, abiotic filters
at the plant. However, it is recommended that deep filters be constructed to accommodate any future BAF
conversion. If BAF is the chosen filtration technology, the new filter facility will have a canopy over the
filters to reduce the amount of sunlight on the filters to limit the amount of biogrowth and algal growth.
Additional chemicals may also be dosed at the filter influent to optimize the BAF performance, such as
caustic and peroxide.
Hazen and Sawyer I Filters 13-3

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 13-1: Existing Filters Basis of Design
Parameter Units Design Criteria
Trough width inches 16
Trough quantity per filter cell --- 3
Filter backwash system — Air and Water
Filters 1,2,4,6, & 7— Leopold (Xylem)
Underdrain Type IMS Cap Style
Filters 3 & 5—AWI stainless-steel
r r unde i n d a
13.2 Filtration System Expansion — Preliminary Design Criteria
Table 13-2 summarizes the design criteria for the proposed filters at the different evaluated plant
capacities. The proposed filters have the same treatment capacity per filter as the existing filters, or
3.2 mgd, assuming a loading rate of 4.0 gpm/SF. The proposed filters will be single-cell as opposed to the
existing dual-cell existing filters, configured in an opposing filter arrangement. This configuration minimizes
footprint and limits pipe gallery congestion.
Table 13-2: Proposed Filter Basis of Design
Design Criteria, Design Criteria, Design Criteria,
Parameter Units Flow of 32 mgd Flow of 38 mgd Flow of 45 mgd
Total number of filters ---- 11 13 15
(n+1)
Number of new filters ---- 4 6 8
Surface area SF 550 550 550
Cells per filter ---- 1 1 1
Maximum filter rate gpm/SF 4.0 4.0 4.0
Abiotic /Conventional Filters
Media configuration ---- 36"Anthracite 36"Anthracite 36"Anthracite
12" Sand 12" Sand 12" Sand
Uniformity coefficient ---- Sand: <_ 1.40 Sand: <_ 1.40 Sand: <_ 1.40
Anthracite: <_ 1.40 Anthracite: _< 1.40 Anthracite: <_ 1.40
Effective size mm Sand: 0.45 —0.55 Sand: 0.45—0.55 Sand: 0.45—0.55
Anthracite: Anthracite: Anthracite:
1.05- 1.10 1.05 - 1.10 1.05- 1.10
Distance between top inches 64 64 64
of media and
underside of trough
Hazen and Sawyer j Filters 13-2

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
13. Filters
13.1 Existing Filtration System
The water treatment plant currently has seven dual-cell filters. Table 13-1 identifies the basis of design for
the existing filters. Filters 1 through 5 and Filter 7 are dual media filters with 36 inches of anthracite and
12 inches of sand. Filter 6 operates in a biological mode and has 48 inches of GAC and 12 inches of sand.
Filters 3 and 5 were recently upgraded to AWI stainless steel filter underdrains. The remaining filters are
equipped with Leopold (Xylem) underdrains. Filters 1, 2, 4, and 7 are now equipped with the latest Leopold
IMS cap design and Filter 6 continues to use the older IMS cap system.
In general, the existing filters are performing well. The WTP has averaged filter run times of about 95 hours
since 2007. Filtered water turbidities averaged 0.06 NTU in the same period. In December 2015, reduced
filter runtimes in the biologically active filter(Filter 6) led GUC staff to pursue a filter surveillance program
with Hazen and Sawyer. This surveillance led to a recommendation from Hazen to replace the media (GAC
and sand) in Filter 6. The underdrains were also inspected and some minor repairs were completed. More
detail of the inspection and repairs to Filter 6 can be found in the Hazen memorandum Recommendations
for Emergency Repairs to Filter 6 Greenville Utilities Water Treatment Plant(January 25, 2016).
In August 2016, GUC staff observed cratering and mounding of the media in Filter 1. Partial excavation of
the media revealed bulging of one of the IMS media retainers on the Leopold SL underdrain. Hazen
recommended a full inspection of the underdrain by Leopold. Media removal and a full inspection of Filter 1
is currently planned for June 2017. More detailed information about the recommended approach for
inspection of Filter 1 can be found in the Hazen memorandum Filter 1 Underdrain Evaluation and
Recommendations(February 23, 2017).
Table 13-1: Existing Filters Basis of Design
Parameter Units Design Criteria
Number of filters ---- 7
Surface area per cell SF 272
Cells per filter ---- 2
Maximum filtration rate gpm/SF 4.06
Permitted filtration capacity mgd 22.3
Filters 1-5, 7 Filter 6
Media configuration ---- 36"Anthracite, 48" GAC, 12"
12" Sand Sand
Distance between top of media and feet 3 3
underside of trough
Approximate available driving head feet 4.8 3.8
Approximate freeboard feet 4 3
Hazen and Sawyer I Filters 13-1

Preliminary Engineering Report
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Table 12-4: Key Biological Filtration Conclusions and Suitability Rankings
Overall
Driver Component Evaluation Method Conclusion Suitability
Nitrification DS water quality Evidence for limited
potential in the analysis nitrification events
distribution system
Water Moderate-
TOCstability /DOC Pilot analysis Improve water stability High
Overall TOC and WRF biofilter conversion Moderate suitability
AOC removal tool
HAAs and THMs Pilot analysis Reduce disinfection
byproduct formation
Disinfection NDMA special sampling, Limited concern for GUC, Moderate
byproducts NDMA pilot analysis reduces NDMA further
Switch to free Pilot analysis GUC cannot switch to free
chlorine chlorine
Manganese breakthrough
Total and Full scale during extreme
Manganese dissolved demonstration, pilot manganese events. Moderate
removal
manganese analysis Caustic enhances
9 Y
manganese removal
Full scale
Turbidity demonstration, pilot No impact is expected
analysis Effluent y Moderate-
water quality Increased bacterial High
Biological growth Pilot analysis concentrations in biofilter
effluent
Full scale
UFRV UFRV demonstration, pilot Decreased UFRV Low
analysis
Chemical Recommended Pilot analysis Caustic or peroxide Moderate
addition chemical addition
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Preliminary Engineering Report
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12.6 Summary of BAF Evaluation Results
Table 12-4 provides summaries of the key BAF components, conclusions, and suitability rankings for
GUC's BAF drivers and concerns, respectively. Biological filtration will improve water stability for GUC
through additional total organic carbon (TOC), dissolved organic carbon (DOC), and AOC removal. Pilot
data indicated that Ozone-BAF could improve DOC removal by 20 percent. AOC removal would likely be
enhanced by 40 percent with BAF. Biofiltration would improve regulated DBP precursor removal by nearly
50 percent. Currently, GUC staff is in compliance with the Stage 2 DBP Rule, so enhanced DBP precursor
removal is not a strong driver for converting to biological filtration.
Biofiltration alone would not provide for enough DBP reduction to support GUC switching secondary
disinfectant from combined chlorine to free chlorine. Research suggests that biological filtration would
provide an effective barrier for taste and odor compounds and emerging contaminants; however, certain
compounds are more recalcitrant to biodegradation and are unlikely to be removed through biofiltration.
GUC staffs current practices have effectively managed algae growth in the pre-sedimentation basin and
taste and odor. Emerging contaminants could become an important driver for conversion to biological
filtration. As discussed in Section 2, promulgation of new rules for emerging contaminants are not expected
in the near-term.
Manganese control was found to be a concern with biological filtration. Biological filtration was effective for
manganese removal at low levels but was not able to control high levels during water quality excursions.
Caustic addition proved to enhance manganese removal in the pilot testing. However, the removal of pre-
filter chlorine feed would require multiple manganese barriers to provide similar process robustness as
compared to current WTP operations.
Biological filters had higher levels of HPC in the effluent. In the pilot columns, coliform concentrations were
fairly low. However, the sloughing of bacteria in the biological filters does present a risk and GUC staff
should consider UV disinfection system to provide an additional barrier for pathogens. Pilot testing and full-
scale demonstration showed that filter runtimes would be lower with biological filtration by 70 percent
during the summer months. Caustic and/or peroxide addition in the filter influent were effective for
enhancing UFRV.
Hazen and Sawyer I Biological Filtration Analysis 12-14

Preliminary Engineering Report
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25,000
20,000
Typical biological
UFRV
Typical Abiotic UFRV
15,000 —
co
co
CC
CD10,000 —
♦
5,000 —
0
Col. 1 Col.2 Col.3 Col.4 Col.5 Col.6 Col. 7 Col. 8
(Cont) (Phos) (pH) (Phos+pH) (Upflow) (Peroxide) (Peroxide+pH) (GUC No. 6)
Figure 12-7: Ozone-BAF Pilot Average Unit Filter Run Volume Results
Hazen and Sawyer I Biological Filtration Analysis 12-13

Preliminary Engineering Report
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0.10 -
0.09 -
0.08 -
0.07
0.06
rn -
E Secondary MCL
0.05 -
a)
co 0.04 -
o -
0.03
0.02 -
Full Scale < 0.01 mg/L
0.01
0.00
Influent Col. 1 Col.2 Col. 3 Col.4 Col. 5 Col.6 Col. 7 Col. 8
(Cont) (Phos) (pH) (Phos+pH) (Upflow) (Peroxide) (Peroxide+pH) (GUC No. 6)
Figure 12-6: Average Ozone-BAF Pilot Dissolved Manganese Results
Hazen and Sawyer I Biological Filtration Analysis 12-12

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
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80 -
Stage 2 (TTHM)
70 -
60 -
Stage 2 (HAA5)
50 -
11)
= 40
= 30 -
20 -
10 -
0
Col.1 Col.2 Cot 3 Col.4 Col.5 Col.6 Col.7 Col.8 Full Scale Full Scale Full Scale
(Cont) (Phos) (pH) (Phos+pH) (Upflow) (Peroxide) (Peroxide+pH) (GUC No.6) (Filter 6) (Combined) (Finished)
milm Total HAA mom Total THM -Series3 Series4
Figure 12-5: Simulated Distribution System Testing with 15 Minutes of Free Chlorine Contact Time
Hazen and Sawyer I Biological Filtration Analysis 12-11

Preliminary Engineering Report
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Coliform and HPC testing, dissolved oxygen (DO) monitoring, and visual observations suggest that there
were no major differences in biological activity between the different chemical conditions. It should be
noted that the pilot filter effluent had high levels of HPC in the effluent. Observed levels of coliforms were
low in the pilot, and continued to improve with time over the course of the pilot. On only one occasion was
a most probable number(MPN) of greater than 200 cells/ml observed.
12.5.2 Ozone BAF Operational Requirements
UFRV is used to compare filter hydraulic performance to normalize for filtration rate and filter surface area.
Figure 12-7 illustrates the average UFRV results for the pilot study. The control pilot columns had
comparable UFRVs to the full-scale biofilter No. 6 with UFRV of approximately 6,500 gal/SF. The upflow
BAF column had the highest UFRV of over 20,000 gal/SF, as expected, since the upflow configuration
likely allowed for some minor bed expansion. Caustic and peroxide addition improved UFRV to
12,050 gal/SF and 9,510 gal/SF, respectively. However, UFRV for the BAF pilot columns, except for the
upflow filter, was significantly less than GUC's abiotic filters (e.g., 14,500 gal/SF).
Hazen and Sawyer I Biological Filtration Analysis 12-10

Preliminary Engineering Report
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Table 12-3: BAF Column Pilot Setup
Column GAC Media Effective
Number Chemical Addition and Dose Source Size Configuration
1 None (control) Henrico 1.35 mm Gravity
2 Phosphorus (0.2 mg/L as P) Henrico 1.35 mm Gravity
3 Caustic(8.9 mg/L) Henrico 1.35 mm Gravity
4 Phosphorus (0.2 mg/L as P) + Henrico 1.35 mm Gravity
Caustic(8.9 mg/L)
5 None Benton 2.0 mm Upflow
6 Peroxide (1.5 mg/L) Henrico 1.35 mm Gravity
7 Peroxide (1.5 mg/L) + Caustic Henrico 1.35 mm Gravity
(8.9 mg/L)
8 None (Control) GUC No. 6 1.39 mm Gravity
12.5.1 Ozone-BAF Water Quality Impacts
To evaluate the impact of BAF on improving distribution system water stability, removal of AOC and
changes to fluorescence Excitation Emission Spectra (EEMs) were evaluated. DOC removal through the
Ozone-BAF pilot columns averaged 12 to 22 percent. The pilot study results suggest that the various
chemical additions tested had minimal impact on full-scale TOC/DOC removal. None of the BAF pilot
columns demonstrated improved UV254 removal compared to abiotic filters. The chemical additions did not
improve UV2s4 removal; however, the addition of caustic seemed to slightly decrease UV2s4 removal.
Simulated Distribution System (SDS) DBP formation tests were conducted to evaluate the performance of
Ozone-BAF for DBP precursor removal. Results from the SDS testing (with 15 minutes of free chlorine
followed by ammonia addition) demonstrate that Ozone-BAF enhances DBP precursor removal such that
DBP levels were 45 to 50 percent lower than with abiotic filters. The combined filter effluent results suggest
that the combined water has the potential to exceed the Stage 2 rules for HAA5; however, GUC staff
finished water results suggest that GUC will meet the Stage 2 rules for TTHM and HAA5 (refer to
Figure 12-5). Results from the SDS testing with free chlorine suggests that the Ozone-BAF process would
not enhance DBP precursor removal sufficientlyto enable GUC to switch to free chlorine disinfection.
The BAF pilot columns was able to meet the secondary MCL of 0.05 mg/L for manganese with relatively
low influent manganese levels (< 0.05 mg/L). Caustic enhanced manganese removal to 76 to 84 percent,
as compared to 20 to 45 percent for the other pilot columns. Figure 12-6 provides the average Ozone-BAF
dissolved manganese concentrations for each column.
Hazen and Sawyer I Biological Filtration Analysis 12-9

Preliminary Engineering Report
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12.4 Distribution System Evaluation
Historical finished water quality and distribution system water quality were assessed, focusing on
nitrification events and DBP formation to provide context for the driver or need to improve distribution
system water quality(e.g., both bio-stability and disinfection byproducts).
12.4.1 Distribution System Evaluation
The potential for nitrification is a primary concern for water systems using chloramines. Nitrification can
lead to a rapid depletion of chloramine residuals, which may subsequently lead to bacterial growth in the
distribution system and possible non-compliance with coliform limits. Total chlorine, monochloramine, free
ammonia, total ammonia, pH, nitrite, nitrate, and HPC are common parameters monitored for nitrification
by other water utilities. In addition to these water quality factors, several physical/operational parameters
including water age and pipe condition are also important.
Water quality data in the GUC system was evaluated to assess historical occurrence of nitrification.
Sample sites were characterized by water age based on distribution system hydraulic modeling. Results
from the distribution system analysis are summarized as follows:
• Nitrification indicators show that some level of periodic nitrification is likely occurring within
the system, at sites with more than 24-hour water age.
• Average total chlorine levels and other nitrification indicators are within acceptable levels.
• Free ammonia, HPC, and nitrite, do approach and exceed suggested action levels on
occasion.
• Regulated DBPs (THMs and HAAs) are currently in compliance.
12.5 Ozone-BAF Pilot Study
The Ozone-BAF pilot was initiated to assess the impact and feasibility of BAF at the WTP. It was operated
for 21 weeks by GUC and Hazen staff from June 8, 2016 to November 3, 2016. The pilot was equipped
with eight columns to test the following six conditions: increased phosphorus, increased pH, peroxide
supplementation, increased phosphorus and pH, increased pH and peroxide supplementation, and an
upflow configuration. The remaining two columns were used as controls. Table 12-3 provides an overview
of the eight columns in the pilot.
Ozonated settled water from the WTP was pumped to a break tank for distribution to the two pilot column
racks. Each column was equipped with an influent pump controlled by a variable frequency drive(VFD).
GUC staff backwashed the filters as needed and Hazen staff made weekly visits to collect data, modify the
pilot, and prepare chemical stocks. GUC laboratory staff collected weekly samples for in-house processing.
Pilot data was screened for quality control, and filter runs were excluded if the average filter turbidity was
greater than 0.25 Nephelometic turbidity unit NTU).
Hazen and Sawyer I Biological Filtration Analysis 12-8

Preliminary Engineering Report
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20,000
Average Filter 1 Average Filter 6
UFRV(Abiotic) UFRV(BAF)
18,000
16,000
•
14,000 -
12,000 — — — — —
U-
10,000 - - - - - - -T—
Cu
Cr)
8,000 - -
•
6,000 -
I
4,000
2,000 - - - - - - -
0
,.00 ,. ,\C3 ,\C0 ,�3 NC:3 ,.rO Ahht\0 '�rO '\CO ' :3 '� '\0 NCO 'NCO 'NCO '�rO '� \CD ,\q0
AV \� 97 \`1� \�O \1O \,1O 97 \� \1 97 \1 \rlO 97 \t� .97 \l \`1 • \lO \7O
q§." '`' 6'`0� `r" A\ ,�\'` .�\'`' .�\'tiD .�\"� q:r NR `L `L�b \D� p�\'` p�\�`0 p�\y� ^4\f L .c§v 0
•Filter 6(BAF) •Filter 1 (abiotic)
Figure 12-4: Full Scale UFRV for Filter No. 1 (Abiotic)and Filter No. 6 (BAF)
Hazen and Sawyer I Biological Filtration Analysis 12-7

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
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o Filter 1 (Conventional) o Filter 6 (BAC)
120 —
100
0
- • .%,:ii.1.*:, -••••,:... ' ,,-..' ... _.,, ,z;7 ,- j. . :,..v.--•:,..:.,, 7 ... -.- -.: . ..-.1ruc.7.1611114:180,
. t. , i i o o % a: 11:•.00
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.
0 I0
8/10/2010 2/26/2011 9/14/2011 4/1/2012 10/18/2012 5/6/2013 11/22/2013 6/10/2014
Figure 12-3: Filter Run Times Observed in Full-Scale BAF Demonstration
Hazen and Sawyer I Biological Filtration Analysis 12-6

Preliminary Engineering Report
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1.40
1.20
1.00 —
J
0.80
y
N
C _
c4 0.60 —
2
Cu
Secondary MCL
0.40
0.00 1 _
49 IC? 19 19 t rLo e 991 15) S ,LO IS' 19 ,Lo ro 15) �O
,\41, Nepe N tiie \� \� 41, ope \� 41/ opti Node NO. NIS N 41.
—Filter 1 —Filter 4 —Filter 6 —CMB Filter —Raw Mn —Series6
Figure 12-2: Total Manganese from Biological Filters from October 2010 to February 2012
Hazen and Sawyer I Biological Filtration Analysis 12-5

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
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90
80 - -
70
60 - - ----
J
0)
E 50 -
vi
a)
a
40 -
a -
Q
30 - --
20 -
10 -
0 - r 1 -1111N=aill
Conventional Filter BAF with Anthracite BAF with GAC Media Post Contactor
Media
Figure 12-1: Aldehyde Levels in Filter Effluent
Hazen and Sawyer I Biological Filtration Analysis 12-4

Preliminary Engineering Report
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12.3 Full-Scale BAF Demonstration
Beginning in 2010, GUC initiated a full-scale demonstration of BAF by converting Filters No. 4 and 6 to
biofilters. The chlorine feed to full-scale Filters No 4 and 6 were stopped in October 2010 to evaluate the
performance of BAF on anthracite media (Filter No. 4) and GAC media (Filter No 6). Filter No. 1 with
sand/anthracite and pre-filter chlorine feed was used a control. Effluent manganese concentrations, effluent
aldehyde concentrations, effluent turbidity, and filter run times were evaluated for Filters No. 1, No. 4, and
No. 6. Updates and extended analysis were performed during the course of this evaluation, specifically to
address several additional water quality concerns and bolster initial findings from the demonstration study.
Aldehydes are simple organic molecules that are used as a proxy for biodegradable organic matter
removal. In the full-scale testing, GUC evaluated removal of aldehydes across conventional abiotic filters,
as well as in two biofilters (anthracite and GAC media). The results suggest that BAF provides improved
aldehyde removal, effectively reducing post-filter aldehydes by nearly 90 percent(refer to Figure 12-1).
While not a direct correlation with AOC, the data indicates that biofiltration would be capable of removing
AOC and improving biological stability significantly.
Figure 12-2 details the historical raw and biologically filtered manganese levels from October 2010 to
February 2012. Historically, the biofilters demonstrated decent manganese control with levels typically
consecutive below the secondary MCL although levels did average 0.02 mg/L higher than in the abiotic
filter. During Hurricane Irene, raw water manganese levels increased up to 1.3 mg/L. During this period, the
biofiltration experienced manganese breakthrough with 16 days of levels exceeding the SMCL. This
demonstrates the risk of BAF in that it is not as robust for manganese control as compared to abiotic filters
during water quality excursions. These data suggest that multiple manganese barriers would be needed
with BAF.
The abiotic filters at the WTP typically achieve 96-hour filter run times. The full-scale BAF observed
seasonal reductions in filter runtimes to as low as 20 hours (refer to Figure 12-3). Shorter filter run times
may impact net water production of the WTP. To exacerbate the situation, seasonal reduction in run time
occurs in the summer, when higher system demands are experienced. Other regional utilities have also
observed significant impacts to capacity, observing summer time BAF"bottlenecks,"which have reduced
firm capacity to less than half of design capacity.
In December of 2015, filter No. 6 run times decreased to below 20 hours. Filter surveillance was conducted
and found the GAC media condition had deteriorated significantly. As a result, the GAC media was
replaced with 12-inches of sand and 48-inches of Norit GAC 816 in March 2016. During the summer of
2016, unit filter run volume (UFRV)was monitored and compared with Filter No. 1 (refer to Figure 12-4).
UFRVs for filter No. 6 (BAF) increased after the media change-out, suggesting that media condition was a
factor in previously observed short run times. During the summer of 2016, the average UFRV for the BAF
filter(6,800 gal/SF)was 53 percent less than the average UFRV(14,360 gal/SF) for an abiotic filter. Even
with new media, BAF performance resulted in seasonal reductions in filter run-time.
Hazen and Sawyer Biological Filtration Analysis 12-3

Preliminary Engineering Report
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Table 12-1: Drivers for BAF Adoption at GUC
I I
Driver Expected Impact Importance at GUC
BAF improves water stability in the Likely important to reduce nitrification
Water stability distribution system through removal of potential in high water age areas.
AOC generated via ozone.
Up to 20% removal of dissolved Not important under current
Disinfection organic matter(DOM)and reduction in chloramination. Important if residual free
byproducts DBP precursors (mostly HAA chlorine desired in the future.
precursors).
Reduced nuisance odor compounds Algae based taste and odor not
Taste and odor such as MIB and geosmin by up to historically observed. However, odor
control 50%. complaints occur when ozone not in
service.
Limited and variable removal of EDCs Not currently regulated, and limited
9
Emerging and PPCPs without ozone (effective evidence of their presence. However,
contaminants when coupled with ozone). Tar River is impacted by agriculture and
Perfluorinated compounds not well urban runoff, along with WWTP point
removed. sources.
Table 12-2: Considerations for BAF Adoption at GUC
Considerations Expected Impact Importance at GUC
High manganese levels can Typically low manganese in raw water,
Manganese removal overwhelm BAF and result in but manganese excursions occur
manganese breakthrough. I occasionally. Multiple treatment barriers
would be required.
Filter effluent microbial Possible increase in effluent Filtration is primary barrier for
quality bacteria levels. pathogens.
Filter run times and Increased fouling leads to Important to net water production and
unit filter run volumes shorter filter run times (24 to reliable capacity.
(UFRV) 40 hours).
Chemical addition may be Caustic and peroxide addition enhanced
Chemical addition needed to optimize biofilter UFRVs.
performance.
Capital and Higher costs to provide deeper BAF requires additional hydraulic head
operational costs filters, canopy, and potentially to optimize UFRV.
intermediate pumping.
Hazen and Sawyer I Biological Filtration Analysis 12-2

Preliminary Engineering Report
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12. Biological Filtration Analysis
12.1 Introduction
BAF is defined as filtration through a granular media bed without the maintenance of a disinfectant residual
across the bed, resulting in a fixed-film, biologically active filter. There has been an increased interest in
implementing BAF throughout the United States due to its ability to improve water quality, water stability,
and DBP removal. BAF is often implemented after ozone treatment in particular, to reduce the
concentration of bioavailable organics produced during ozonation and to control biological (re)growth in the
distribution system.
Many of the potential benefits, as well as challenges related to implementing BAF, are site-specific and
rooted in the water quality of a particular water system. Therefore, it is prudent to consider a holistic
evaluation of the costs and benefits of BAF. To assist GUC in evaluating whether BAF represents a viable
and cost effective option to meet the desired water quality benefits, a multiple-step BAF analysis was
performed. In support of this holistic evaluation of BAF for GUC, Hazen performed the following.
• Identified BAF drivers and considerations for implementation.
• Evaluated the results of the full-scale BAF demonstration.
• Performed a distribution system evaluation to contextualize the disinfection byproduct
drivers and distribution system stability.
• Performed an Ozone-BAF pilot study to understand the impact of BAF operational
strategies on water quality and hydraulics.
Additional sources of information were also evaluated, including the Water Research Foundation 4496
Tool, a literature review, and a historical data analysis to draw conclusions regarding biological filtration at
the WTP. The full pilot study results are presented in Appendix B.
12.2 BAF Process Drivers and Considerations
While BAF can improve water quality, particularly post-ozone, by further reducing organics and improving
water quality, implementation of BAF has also been linked to operational and water quality challenges,
including reduced filter run times, turbidity breakthrough, increased levels of indicator organisms (defined
by HPC and total coliforms (TC)) in the BAF effluent, and mixed performance for management of
manganese. Some of these challenges may be addressed by design and operational strategies, but it is
important to identify and contextualize important drivers and challenges in order to evaluate the feasibility
of BAF for GUC.
Table 12-1 summarizes the drivers for BAF at GUC, providing information on expected magnitude of the
driver. As part of a holistic BAF evaluation, water quality and operational considerations associated with
implementation of BAF were evaluated. Table 12-2 summarizes the considerations and expected impacts
to GUC.
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Preliminary Engineering Report
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• Provide stub-out in new filter effluent piping for additional ozone cooling water capacity and
redundancy for future cooling water system upgrades.
• Install ozone monitors on off-gas for each contactor to monitor ozone transfer efficiency.
Evaluations in this PER demonstrate that upgrades to ozone generation capacity will be needed when the
WTP expands beyond 32 mgd. Based water demand projections, the expansion to 32 mgd should meet
the GUC system needs through 2034. The GUC Water Treatment Facilities Master Plan (HDR, 2012)
indicated that the ozone generators should useful lifespan through the year 2022. To provide reliable
service, the ozone generators should be upgraded in the future and generation capacity be increased to
accommodate future WTP capacities. Therefore, we recommend that an ozone facility assessment be
conducted again in 2020 to assess the appropriate timing for generator replacement.
To allow for additional cooling water needs in the future, a new 8-inch ozone cooling water line should be
routed to the western side of the ozone facility. The ozone cooling water piping will branch from new filter
effluent piping installed during the 32 mgd expansion. The ozone cooling water line will penetrate and stub
out through the wall space between contactors 2 and 3, where the current bisulfite pump is located
(Figure 11-8). GUC has indicated that a spare ozone cooling water pump is on hand in the event an
existing pump is out-of-service. If a fourth OCW pump is installed in the future, GUC staff may consider the
possibility of adding redundancy in the cooling water loop.
fl i[ 1r - I I ' L I I I, .. � .
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i III
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1 '1 �T
8" OCW pipe from
[x. Wall penetration
� � AT0.Y6 between ' k Future OCWP-4
new FW piping Contactor 2 &3
Figure 11-8: Future Ozone Cooling Water Piping System Layout
Hazen and Sawyer I Ozone System 11-17

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
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disinfection profile summary revealed log-inactivation for Giardia can be achieved with the existing ozone
generators for WTP capacities of 22.3 and 32 mgd. Ozone generation capacity was marginal at 38 mgd
and was not adequate for meeting Giardia removal goals at a 45 mgd plant capacity.
Table 11-9: Summary of Ozone CT Evaluation with Existing Generators
Giardia Log-
WTP Capacity No. of No. of Firm Max Ozone Inactivation
(mgd) Generators Contactors Dose (mg/L) Requirement
22.3 3 4 9.7 Meets
32 3 4 6.7 Meets
38 3 4 5.7 Marginal
45 3 4 4.8 Does Not Meet
Based on the expected remaining service life, the ozone generators would require replacement prior to
2035 when expansion to 38 mgd is needed. Therefore, when ozone generators are replaced, GUC staff
should provide additional generation capacity at that time to meet future needs. GUC could either replace
the existing 900 Ib/d generators with new 1,300 Ib/d or replace the existing generators and install a fourth
generator. Table 11-10 summarizes the benefits of additional ozone generation capacity for WTP capacity
increments of 38 and 45 mgd. The CT calculations were conducted at 38 and 45 mgd based on the
proposed future ozone generator upgrades and confirmed Giardia inactivation requirements would be met.
Table 11-10: Summary of Ozone Generation Capacity with Future Generator Upgrades
WTP Ozone Total Ozone Firm Ozone Firm Max
Capacity No. of Generator Generation Generation Ozone Dose
(mgd) Generators Capacity (Ib/d) Capacity (lbld) Capacity (lb/d) (mglL)
22.3 3 900 2700 1,800 9.7
32 3 900 2700 1,800 6.7
38 3 1,300 3,900 2,600 8.2
45 3 1,300 3,900 2,600 6.9
Assumes existing generators have been replaced by new 1,300 lb/d generators.
11.2 Proposed Improvements
Evaluations of the existing ozone facility at the WTP have led to the recommended improvements to be
included in the Phase 1 WTP upgrades to enhance ozone operation and performance, as follows:
• Inspection of all contactors and diffusers.
• Replace gas flowmeters (GOX meters)to provide appropriate turndown
Hazen and Sawyer I Ozone System 11-16

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
The following CT evaluation assumptions and worse-case scenarios were used based on WTP data:
• Peak flow at the WTP was evaluated at 22.3, 32, 38, and 45 mgd.
• Contactors operating in parallel.
• CT based on minimum observed temperature of 5°C.
• CT based on maximum plant flow rate at each scenario.
• Filter influent flume at a minimum water surface elevation of 37.7 feet.
• Disinfection credit was not awarded for cell 1 of each contactor.
• Baffle factors for each cell determined in previous tracer study
• EPA SWTR approves a 2.5-log credit for Giardia removal and 2.0-log credit for virus
removal in plants treating by conventional filtration.
Table 11-8 summarizes the firm ozone generation capacity and firm maximum ozone dose available under
existing WTP conditions and for the proposed WTP capacity increments. The ozone system is capable of
providing a firm maximum dose of 9.7 mg/L (with one ozone generator out of service). At a WTP capacity
of 32 mgd, the firm maximum dose would decrease to 6.7 mg/L. This exceeds the historical maximum dose
at the WTP with intermediate ozonation only in operation. Therefore, the existing ozone system has
sufficient generation capacity to meet the needs for intermediate ozonation at 32 mgd. GUC staff has
historically not operated the pre-ozonation and there is not a strong need for pre-ozonation in the future
unless GUC converts to biological filtration. At future WTP capacities of 38 or 45 mgd, the firm maximum
dose that the existing ozone generators could provide would not be sufficient for future needs.
Table 11-8: Summary of Ozone Generation Capacity—Existing System
WTP Ozone Total Ozone Firm Ozone Firm Max
Capacity No. of Generator Generation Generation Ozone Dose
(mgd) Generators Capacity (Ibld) Capacity (lb/d) Capacity (Ib/d) (mg/L)
22.3 3 900 2700 1800 9.7
32 3 900 2700 1800 6.7
38 3 ' 900 2700 1800 5.7
45 3 1 900 2700 1800 4.8
HDR ozone facility assessment determined that ozone generators will reach the end of remaining service life by
this capacity time frame.
The firm max dose was applied to each CT calculation to generate Table 11-9, which defines whether or
not adequate log-inactivation was met for Giardia at each WTP capacity scenario. Meeting the Giardia
removal goal was considered the main focus of this assessment. The CT evaluations in Section 15
demonstrated that sufficient virus removal will be achieved through contact time within the WTP. The
Hazen and Sawyer I Ozone System 11-15

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
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9/1/14 12/10/14 3/20/15 6/28/15 10/6/15 1/14/16 4/23/16 8/1/16
Figure 11-7: Log Inactivation Achieved Through Intermediate Ozone
Hazen and Sawyer I Ozone System 11-14

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
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Figure 11-6: Ozone Concentration versus Gas Flow Based on Historical Operational Ozone Data
Hazen and Sawyer I Ozone System 11-13

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
18.0 —
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Figure 11-5: Ozone Concentration Based on Historical Ozone Operation Data
Hazen and Sawyer I Ozone System 11-12

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
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Figure 11-4: Historical Ozone Energy Efficiency
Hazen and Sawyer I Ozone System 11-11

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
•Cont 1 Cell 1 •Cont 1 Cell 2 •Cont 1 Cell 3
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Figure 11-3: Contactor 1 Ozone Residual Concentrations
Hazen and Sawyer I Ozone System 11-10

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Cont 1 Dosage (mg/L) - -Cont 2 Dosage (mg/L) Cont 3 Dosage (mg/L) ---Cont 4 Dosage (mg/L)
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Figure 11-2: Intermediate Ozone Dose Trends per Contactor
Hazen and Sawyer I Ozone System 11-9

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
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Figure 11-1: Total Ozone Usage at the GUC WTP
Hazen and Sawyer I Ozone System 11-8

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
ratio (including downstream disinfection segments) alarm set point at the WTP is set at 1.5 to provide an
operational buffer to meet the required CT.
A contact time (CT) evaluation was conducted to assess ozone system capacity for meeting disinfection
requirements for future WTP capacities of 32, 38, and 45 mgd. A tracer test was performed in 2010 to
evaluate CT and baffle factors in the ozone contactors (Tracer Testing Results Summary: Evaluation and
Upgrade of Water Treatment Plant Ozone System, AH Environmental, 2010). Tracer tests were conducted
at flowrates of 4.0 mgd and 11.25 mgd through each contactor and the baffle factors were determined for
each contactor cell.
Hazen and Sawyer I Ozone System 11-7

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 11-7: Historical Ozone Dose Operational Data
Parameter Historical Ozone Dose(mg/L) 1
Maximum 4.73
Minimum 0.69
Average 2.33
98th Percentile 4.31
Historical data WTP ozone operational data (2014—2016)
Figure 11-3 illustrates the ozone residual concentrations in Cells 1, 2, and 3 of Contactor 1. Ozone
residuals are measured by independent Rosemount ozone residual analyzers for each cell. This data
shows that ozone residuals are often completely dissipated by Cell 3. The remaining contactor cells offer
additional contact time and the opportunity for ozone decay. A calcium thiosulfate system and diffusers in
the last contactor cell and effluent channels are available if needed for ozone residual scavenging. The
calcium thiosulfate system includes a 300 gallon high density polyethylene (HDPE) day tank and three
metering pumps. However, this system has rarely been needed or operated. Based on historical power
usage data shown in Figure 11-4, the ozone system efficiency has improved. In particular, ozone efficiency
improved in 2016 with most data in the optimal range of 2 to 3 kilowatt per hour per pound (kWh/lb).
The optimal range for ozone systems in terms of LOX usage and energy efficiency is nearly 10 percent
ozone concentration. The ozone generators at GUC are sized for 900 Ib/d based on 8 percent. Figure 11-5
illustrates historical ozone concentration trends. Ozone concentration is often well below 8 percent.
Figure 11-6 shows the relationship between historical ozone concentration and gas flow. This suggests
that low ozone concentration is related to higher GOX flow. Based on discussions with GUC staff, GOX
flow has be increased to ensure the flowmeters are within acceptable range for control. Typically, GUC has
operated two intermediate contactors at a time as a strategy to optimize gas flow to the contactors. To
avoid stagnation and poor water quality in offline contactors, GUC typically rotates the online contactors
every 3 to 4 days. It is recommended that the GOX flowmeters be replaced to provide effective control in
order to optimize ozone concentration and overall system operation.
11.1.4 Contact Time Evaluation
Based on the WTP achieving 2.5-log credit for Giardia removal and 2.0-log credit for virus removal through
conventional treatment, the WTP must provide at least 0.5-log Giardia inactivation through chemical
disinfection to meet disinfection guidelines. The historical log inactivation achieved in the intermediate
ozone is shown in Figure 11-7. Historically, the log inactivation provided by the ozone system has been
close to 0.5 with several days below 0.5 log. In these instances, GUC has met treatment requirements
through secondary disinfection practices (i.e. free chlorine). The alarm setpoint for the total log inactivation
Hazen and Sawyer I Ozone System 11-6

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
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The hydraulic detention time provided in the existing contactor at current and future flows is summarized in
Table 11-5. For a WTP capacity of 38 mgd, sufficient hydraulic detention time is provided in the existing
contactors. Additional contactors could be constructed at a WTP capacity of 38 mgd as an alternative to
upsizing influent piping. However, additional ozone contactors are required at a 45 mgd WTP capacity.
Table 11-5: Ozone Contactor Summary for Proposed Upgrades
WTP Capacity (mgd) No.of Contactors Contactor HRT(min)
22.3 4 24
32 4 17
38 4 14.1
45 5 12
Assumes one additional ozone contactor is added.
11.1.3 Intermediate Ozone System Performance
Historical ozone generation data from 2014 to 2016 is provided in Table 11-6. The data demonstrates
ozone generation has ranged from 61 Ib/d to 541 Ib/d under an average WTP flow of 12.7 mgd.
Figure 11-1 provides a plot of ozone usage recorded from September 2014 through August 2016. The data
reveals an expected seasonal trend to ozone usage with increased usage during the summer months.
This trend is affected by many factors and water quality parameters such as: temperature, WTP flow, pH,
turbidity, organic matter, color, and presence of inorganics (e.g., manganese and iron).
Table 11-6: Historical Ozone Generation Operational Data
Parameter Historical Ozone Generation (Ib/d) I
Maximum 541
Minimum 61
Average 236
98th Percentile 443
'Historical data WTP ozone operational data(2014—2016).
A statistical summary of historical ozone dosing data based on data from 2014 to 2016 is provided in
Table 11-7. The average ozone dose in the intermediate contactors is 2.3 mg/L with a maximum dose of
4.7 mg/L. Ozone dose trends are shown for each ozone contactor in Figure 11-2. The higher ozone doses
for Contactor 1 in 2015 suggest failed diffusers or leaks in the ozone solution lines. GUC staff confirmed
that repairs were made to diffusers in Contactor 1 in October of 2016. Ozone monitors on the off-gas
system for each contactor are recommended to assist GUC staff with monitoring of ozone transfer
efficiency which would assist with detection of possible diffusers or ozone solution issues in the future.
Hazen and Sawyer I Ozone System 11-5

Preliminary Engineering Report
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Table 11-4: Design Criteria for the Intermediate Ozone System
Parameter Units Design Criteria
Number of Contactors ---- 4
Number of Cells per Contactor ---- 6
Contactor Length feet 50
Contactor Width feet 12
Contactor Depth feet 21
Contactor Volume gallon 94,200
Contactor HRT at 22 mgd minutes 24
Dosing Method --- Diffusers
Number of Ozone Generators 3
Ozone Generator Capacity, 8% Ib/d 900
Flow Pattern ---- Parallel
Feed Gas Source ---- Liquid oxygen
Ozone Destruct ---- Heat assisted catalytic destruct system
An ozone facility assessment was conducted in March 2012 and the results are documented in GUC Water
Treatment Facilities Master Plan Technical Memorandum#8(HDR, 2012). The assessment concluded that
the ozone generators and power supply units are providing reliable operation and in good working
condition. The projected useful lifespan of the equipment was determined to be around 2022 for the
ozonators and 2030 for the PSUs.
11.1.2 Intermediate Ozone Hydraulic Evaluation
Per Section 7, hydraulic profiling determined that the contactors are limited to a flow of 8.85 mgd per
contactor at a future WTP capacity of 35.4 mgd (Table 7-1). At the future flow, hydraulic limitations will
cause submergence of the sedimentation basin weirs. The hydraulic limitation is due to excessive headloss
developed in the existing 24-inch diameter ozone influent piping. Since lowering the ozonated water
effluent channel set-point would reduce the hydraulic head over the filters and could impact filter runtimes
and performance, this option was considered undesirable. It is recommended that the 24-inch ozone
influent piping, flowmeter, and control valve be replaced with 42-inch to alleviate headlosses when the
WTP capacity reaches 38 mgd. The hydraulic profile development and construction sequencing associated
with the ozone influent piping upgrades are further described in Section 7.
Hazen and Sawyer I Ozone System 11-4

Preliminary Engineering Report
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Table 11-3: Permanganate Contact Time in New Clarification Train
Permanganate Contact Time (min)
WTP Flow(mgd) Without Contactor With New Contactor
32.0 5.6 13.6
38.0 2.8 6.8
11.1 Intermediate Ozone
11.1.1 Existing Intermediate Ozone Facilities
Intermediate ozonation is used at the WTP for primary disinfection as well as oxidation of iron, manganese,
and other constituents. The ozone system consisting of three 900 pound per day(Ib/d) ozone generators
and four intermediate ozone contactors. Each contactor has six cells each with ozone diffusers in Cells 1
and 3. The contactor depth of 21 feet helps promote high transfer efficiency. The diffuser system in Cell 1
is supplied by a 3-inch stainless steel ozone line and a 2-inch line in Cell 3. Flow through the intermediate
ozone contactors is controlled using a mag meter and modulating valve on each influent line. Table 11-4
summarizes the design criteria for the intermediate ozone system components.
LOX is the feed e gas source for the ozone system and is stored on site in two 13,000 gallon LOX storage
9
tanks adjacent to the intermediate ozone building. There are two ambient vaporizers for converting LOX to
gaseous oxygen (GOX). GUC staff purchases LOX and leases the LOX system from Matheson. GOX is
conveyed to the three ozone generators which are powered by individual power supply units (PSU's). The
ozone generators manufactured by Ozonia were installed in 2004. The cooling system includes three open
loop ozone cooling water pumps. Water supply for the ozone cooling water pumps comes from an 8-inch
header encased in concrete below the ozone pipe gallery that ties into 48-inch filter effluent line. Off-gas is
captured and conveyed to two catalytic ozone destruct units preceded by a heater. The ozone destruct
units are connected to the pre-ozone and intermediate contactors.
Hazen and Sawyer I Ozone System 11-3

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
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effectively utilized and the detention time of the water flowing through the reactor may be significantly
shorter than the theoretical reactor detention time. It should also be noted that the Pre-Ozone contactor
cannot be effectively operated as an ozone contactor under the surcharged condition. Ozone reactors
require headspace to allow for off-gas of ozone for subsequent collection and destruction. Additionally,
hydraulic detention time at a WTP flow of 22.3 mgd is approximately 3.2 minutes, which is less than the
optimal range for raw water ozonation. The additional contact time for sodium permanganate provided by
the raw water ozone contactor is summarized in Table 11-2.
Table 11-2: Existing System Contact Time Achieved for Permanganate
Permanganate Contact Time (min)
WTP Flow(mgd) Without Contactor With Contactor
13.3 2.5 8.3
22.3 1.5 5.0
GUC staff has not historically utilized raw water ozonation and there has not been a demonstrated need
based on past WTP performance. Since coagulation reduces ozone demand by removing a significant
portion of the NOM, intermediate ozonation is more efficient than raw water ozonation for achieving most
water quality goals such as control of iron, manganese, taste and odor compounds, and emerging
contaminants.
Hazen recommends relocating the raw water rate-of-flow controller from its current location, downstream of
the Pre-Ozone contactor, to the yard piping upstream of the Pre-Ozone contactor. Relocating the rate of
flow controller will lower the water level in the contactor and increase the range of flows that the contactor
can accept before the underflow baffle is overtopped and the reactor is surcharged.
It is not recommended to provide additional raw water ozone capabilities with the new treatment train as
part of the Phase 1 upgrades. A new preoxidation contactor is proposed upstream of the new rapid mix
facility to provide sufficient contact time for sodium permanganate at the expanded WTP capacity. The
contactor will be designed to allow for conversion to a pre-ozone contactor; however, new sidestream
injection pumps, ozone injection and ozone offgas destruct at the new contactor are not recommended for
Phase 1. Instead, the contactor will be used to provide additional detention time for sodium permanganate.
If GUC staff elects to convert completely to biological filtration, then the contactor could be upgraded to
provide an additional manganese control strategy at the WTP. The proposed 56,000 gallon raw water
contactor would provide the additional contact time for sodium permanganate, summarized in Table 11-3.
At a future 45 mgd plant capacity, an additional contactor volume of 28,000 gallons would be required.
Hazen and Sawyer I Ozone System 11-2

Preliminary Engineering Report
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11. Ozone System
Pre-ozonation and intermediate ozonation were constructed in 2004. One pre-ozone contactor is located
upstream of the rapid mix and is designed to provide a 3.2 minute detention time. Ozone is injected into
raw water via sidestream injection system. Two 2,000-gpm sidestream injection pumps located in the
intermediate ozone facility pipe gallery pump ozone solution to the injection point in vault upstream of the
pre-ozone contactor. Design criteria pertaining to the pre-ozone contactor and its components are
summarized in Table 11-1. The raw water ozone system was designed to oxidize iron, manganese, and
taste and odor compounds. However, GUC staff does not currently practice pre-ozonation at the WTP.
Raw water flow is still routed through the contactor for additional contact time for sodium permanganate
when it is being fed for manganese control.
Table 11-1: Design Criteria for Pre-Ozone System
Parameter Units Design Criteria
Number of contactors ---- 1
Length feet 63
Width feet 7
Depth feet 15
Tank volume gallons 49,500
Tank hydraulic detention time at minutes 3.2
22.3 mgd
Number of baffle walls ---- 2
Ozone sampling points ---- 2
Dosing method ---- Sidestream injection
Sidestream pumps, number of units ---- 2
Sidestream pumps, capacity gpm 2,000
Sidestream pumps, TDH feet 110
Feed gas source ---- Liquid oxygen
Ozone destruct ---- Heat assisted catalytic destruct system
There are hydraulic limitations associated with the existing pre-ozone contactor. Currently, there is not
sufficient freeboard in the contactor at higher flows so the top slab of the contractor is often surcharged,
which results in water overtopping the underflow baffle and short circuiting the reactor. Further, GUC staff
have observed inconsistent residual permanganate concentrations after the raw water contactor above 17
mgd, and loss of preoxidation performance above 19 mgd. This is consistent with the predicted short-
circuiting condition where the water overtops the underflow baffle and will flow directly across the top of the
tank to the overflow baffle, before exiting the tank. Under this condition, the volume of the reactor is not
Hazen and Sawyer Ozone System 11-1

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Hazen CLARIFICATION BASINS

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
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Figure 10-3: Illustration of SuperPulsator®Technology(courtesy of Infilco Degremont, Inc.)
Another design consideration for the new high-rate clarification trains is the location and orientation of
these new facilities on the existing plant site. Several conceptual site plans were developed for both the
inclined plate and the SuperPulsators®technologies to compare the different clarification capacities and
different configurations on the plant site. For both SuperPulsators®and plate settlers, capacity increments
of 5, 7 and 10 mgd were compared to ensure that the timing of the expansions were optimized and the
physical size of the basins were configured properly on the plant site. A SuperPulsator®capacity of 10 mgd
was determined to be optimal use of the available site footprint at the ultimate buildout capacity.
Figure 10-4 illustrates the site layout of the proposed clarification basins. Locating the new clarification
basins south of the existing sedimentation basins will use existing space and limit the impact to the existing
road on the west side of the plant. However, this configuration will separate the new processes from the
existing infrastructure and thus limit operator accessibility. This layout configuration will also require
significant infrastructure changes to convey settled water to the intermediate ozone contactors. A second
layout option is to use the space to the west of the ozone facility to keep processes together and provide a
coherent flow to and from existing facilities. This option will have a greater impact on the access road to the
raw water pump station. This western location may also limit an expansion of the ozone facility; however,
this layout option allocated space for two additional ozone contactors.
The SuperPulsator®technology was the selected clarification technology for the plant expansion based on
several factors. The SuperPulsator®technology maximizes the available space on the existing plant site.
This technology also has a proven performance record with treating similar raw water of similar quality at
other utilities in the region. SuperPulsator®basins will also eliminate the need for separate flocculation
basins, further reducing the required building footprint. The optimal location of the SuperPulsator®basins
and associated rapid mix facility is west of the existing ozone facility with flow running north towards the
existing filters. The configuration allows for more direct access between existing facilities, easy access
between existing and future facilities, and adequate space for buildout capacity.
Hazen and Sawyer I Coagulation, Flocculation, and Clarification 10-8

Preliminary Engineering Report
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Greenville Utilities Commission
Table 10-5: Comparison of Clarification Technologies
SuperPulsator® Plate Settlers
• More compact footprint • Larger footprint
• No flocculation basins • Coagulation process similar to existing basins
• Coagulation chemistry may vary from • Operates well over wide range of flows and
existing basins water quality
• Minimum flow for optimal performance • Multiple suppliers
• More sensitive to changes in flow
• Less mechanical equipment
• Sludge collection included
• One supplier
The SuperPulsator® is a solids blanket-type, high-rate, upflow clarification technology. Figure 10-3
illustrates the various components. Coagulated water from the upstream rapid mix process transfers to a
vacuum chamber that opens to a distribution channel. The water enters the lower portion of the clarifier
through a series of laterals with orifices that feed off the distribution channel. Flocculation occurs as the
water travels up through the solids blanket that receives subtle pulsations created by the pulsation system
consisting of a vacuum pump and vent valve assembly. Flocculated particles formed through this process
collect on plate settlers, slough off, and fall into the solids blanket. Typically, the solids blanket is
maintained at approximately 10 feet above the basin floor. Frequency and duration of blowdown of the
solids concentrators helps control the depth of the blanket. The sludge blanket extends into the plate
settlers. Lighter particulates circulate between the plates encouraging solids contact and the solids that
slough off the plates effectively capture these lighter particulates. Clarified water collects uniformly across
the settling area through submerged orifice pipe laterals. Table 10-6 summarizes the preliminary design
parameters for the SuperPulsator®facilities to accommodate the different plant capacities under
consideration.
Table 10-6: Summary of SuperPulsator®High Rate Clarification Technology Basis of Design
SuperPulsator® Design Criteria per Plant Expansion Phase
SuperPulsator®
Parameter 32 mgd 38 mgd 45 mgd
Capacity per unit 10 mgd 10 mgd 10 mgd
Number of units 1 2 3
Basin dimensions 72ftx20ftx17ft 72ftx20ftx17ft 72ftx20ftx17ft
(LxWxD)
Loading rate 2.5 gpm/SF 2.5 gpm/SF 2.5 gpm/SF
Hazen and Sawyer I Coagulation, Flocculation, and Clarification 10-7

Preliminary Engineering Report
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Greenville Utilities Commission
10.3 Evaluation of High-Rate Clarification for Existing Sedimentation Basins
10.3.1 Modification of Existing Sedimentation Basins
Inclined plates and tube settlers are technologies capable of increasing the treatment capacity of
conventional sedimentation basins. Addition of these technologies to existing basins increases the effective
settling area of the basins allowing a utility to maximize the capacity of the existing infrastructure. While
typically more costly, plate settlers provide a more robust design and greater service life than tube settlers.
Therefore, an evaluation of retrofitting the existing sedimentation basins with plate settlers offered an
opportunity to assess if the plates provided a viable and economic means to capture greater treatment
capacity within the existing process infrastructure. The evaluation also considered the continued use of the
existing rapid mix and flocculation basins at higher plant flows and the relative impact to industry-accepted
design standards for these processes.
The plate settler evaluation considered both hydraulic and cost implications. Increased flow to each
sedimentation basin with the addition of plate settlers increased the headloss across the basins.
Subsequently, the additional headloss increased the water surface elevation observed in the upstream
flocculation and rapid mix basins. The capacity of the existing sedimentation basins could be increased
using plate settlers to approximately 24 mgd without major impacts to existing facilities.
At flows greater than 24 mgd. water levels would be at the bottom of the elevated slabs causing uplift
forces. The available freeboard in the rapid mix basins would be reduced to less than one foot. By raising
the elevated slab of the rapid mix basins, the sedimentation capacity could increase to 27 mgd using plate
settlers. It should be noted that raising the elevated slab also requires modifications to the existing process
mixer shafts and isolation gate stems to accommodate this structural alteration.
Two options are available to address this hydraulic limitation. Structural modifications may be implemented,
but the modifications are significant and will impact the existing sedimentation and flocculation basin
structures (e.g., elevated slab/walkways and isolation valve and gates modifications). The capital cost
opinion for these structural modifications is estimated at approximately $3.3 million. The second option is to
de-rate the capacity of the existing sedimentation basins, which would eliminate the capacity benefit of the
plate settlers. An interim increase in plant capacity using plate settlers is invasive to plant operations, is not
cost effective, and impacts future expansion greater than an interim plant capacity of 27 mgd. Considering
demand projections and industry-accepted capacity planning practices, the recommendation is for GUC to
pursue additional treatment capacity with the addition of new process, which avoids a significant
investment that does not provide long-term value.
10.3.2 New Clarification Basins
New clarification trains equipped with either inclined settling plates or the SuperPulsator®technology were
evaluated for expansion of clarification capacity. The two clarification options were compared for
effectiveness, footprint, and capital cost for each system. Table 10-5 provides a synopsis of the relative
differences between the two technologies given the identified comparison criteria.
Hazen and Sawyer I Coagulation, Flocculation, and Clarification 10-6

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RAPID MIX WITH IN-LINE
Hazen MIXING TECHNOLOGY
R_ s

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 10-3: Summary of Proposed Vertical Rapid Mix Facility Design Criteria
Parameter Units Design Criteria
Configuration Single stage
Number of trains ---- 2 expandable to 3
Capacity, per train mgd 15
Side water depth feet 10.0
Length feet 8.0
Width feet 8.0
Volume per train CF 640
Volume per train gallons 4,787
Mixing intensity at 15 mgd s-1 750
Detention time, all basins in service sec 41.4
Detention time, one basin out of sec 27.58
service
Both rapid mix facility designs will incorporate a splitter box to distribute flow evenly to the new flocculation
and clarification trains. Adjustable weir gates will achieve an accurate flow split and provide isolation of an
individual flocculation and sedimentation train. Table 10-4 summarizes the advantages and disadvantages
identified for implementation of the two rapid mixing configurations. The vertical mixing option would be the
most similar to the existing rapid mix facility.
Table 10-4: Advantages and Disadvantage of Vertical and Inline Rapid Mixers
In-line Mechanical Mixers Vertical Mixers
Pros Cons Pros Cons
• Effective mixing with • Requires larger • More compact • Mixers and
less energy over a diameter piping / footprint SuperPulsator®
broader range of flow valves • Lower overall equipment located
• Building allows for • With building, costs outdoors or in
mixers and higher capital separate enclosure
SuperPulsator® costs and larger ' Common wall •
construction Higher motor HP for
equipment to be indoors footprint reduces costs similar mixing
• Limits routing of • Same technology • Require crane for
chemical feed lines as existing mixer removal
outdoors
• Easier access for
maintenance
Hazen and Sawyer I Coagulation, Flocculation, and Clarification 10-3

Preliminary Engineering Report
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There are six existing conventional sedimentation basins. Four of the basins are original to the WTP and
two were added as part of the 1999 expansion. Each sedimentation basin is equipped with two mechanical
sludge collection systems consisting of a traveling vacuum header displaced by an electric pulley drive unit.
The design parameters for each sedimentation basin are summarized as follows:
• Detention time = 3.4 hours
• Overflow rate = 0.5 gpm/SF
• Treatment capacity 3.7 mgd
P Y=
• Weir overflow rate = 100,725 gpd/ft
• Flow through velocity = 0.28 ft/s
10.2 Evaluation of Rapid Mixing Alternatives
Two configurations for the new rapid mix were evaluated for the GUC WTP expansion. The two mixing
options include in-line mechanical mixers and compartmentalized concrete basins with vertical mixers.
Figures 10-1 and 10-2 provide the preliminary layouts developed for both rapid mixing configurations.
For the in-line mechanical rapid mix option, a new rapid mix facility would house two in-line mechanical
mixers providing redundancy and reliability to the process. The new facility would offer adequate space for
an additional third train for future treatment capacity. This facility could also house new chemical day tanks
and feed equipment for alum, caustic, and polymer systems as well as the sludge blowdown valves for the
SuperPulsator®clarification option. Table 10-2 summarizes the proposed conceptual design of the in-line
mechanical mixer rapid mix facility.
Table 10-2: Summary of Proposed In-line Rapid Mix Facility Design Criteria
Parameter Units Design Criteria
Configuration ---- Single stage
Number of trains ---- 2 expandable to 3
Capacity, per train mgd 15
Pipe diameter inches 36
Mixing intensity at 15 mgd s-1 3,500
Detention time sec 41.4
For the vertical mixer option, two single-stage trains of concrete basins with variable speed vertical mixers
will be required. The two trains will provide redundancy in the event a vertical mixer is out of service for
maintenance or repair. Raw water flow control and measurement would be provided in a separate vault
located along the new raw water piping feeding to the new facility. An adjacent building would be needed to
house the new chemical feed equipment. Table 10-3 summarizes the preliminary design details of the
rapid mix facility design utilizing vertical mixers.
Hazen and Sawyer Coagulation, Flocculation, and Clarification 10-2

Preliminary Engineering Report
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Greenville Utilities Commission
10. Coagulation, Flocculation, and Clarification
10.1 Summary of Existing System
The existing water treatment plant utilizes conventional coagulation, flocculation, and sedimentation
technologies. The coagulation stage of treatment consists of one two-stage rapid mix basin configured for
either series or parallel operation. Each compartment contains a constant speed vertical mixer used to
blend coagulation chemicals into the raw water. Alum, caustic, and polymer can be fed upstream of the first
rapid mixer or downstream of the second rapid mixer. Table 10-1 summarizes the size and age of each
mixer utilized in the rapid mix and flocculation processes.
Basic design parameters for the existing rapid mixers are as follows:
• Detention time (two basins in series) at treatment capacity (22.3 mgd)—67.6 seconds
• Mixing intensity at treatment capacity (22.3 mgd) and 20°C—405 sec-1
Downstream of the rapid mix basins, there are nine flocculation basins each equipped with a variable-
speed vertical mixer. The basins are separated by wooden baffles and operated in a series configuration.
Polymer can be fed downstream of the first, fourth and seventh stages. Basic design parameters for the
existing flocculation basins are as follows:
• Detention time (nine basins in series) at treatment capacity(22.3 mgd)—30.8 minutes
• Mixing intensity at treatment capacity (22.3 mgd) and 20°C
Table 10-1: Summary of Age and Year Installed for Existing Rapid Mixers and Flocculators
Motor Design Mixing
Mixer Horsepower Year Installed Equipment Age Intensity '
Rapid Mixer- 1 7.5 1983 34 405 sec-1
Rapid Mixer-2 7.5 1983 34 405 sec-1
Flocculator- 1 2 1983 34 80 sec-1
Flocculator-2 2 1983 34 71 sec-1
Flocculator-3 2 1983 34 62 sec-1
Flocculator-4 2 1983 34 53 sec-1
Flocculator—5 2 1983 34 44 sec-1
Flocculator-6 2 1983 34 35 sec-1
Flocculator-7 2 2002 15 26 sec-1
Flocculator-8 2 2002 15 17 sec-1
Flocculator-9 2 2002 15 8 sec-1
'Average of nine flocculation basins equals 44 sec-1.
Hazen and Sawyer I Coagulation, Flocculation, and Clarification 10-1

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�" -- PARnn�raeo PtaiNc r�N PRE-SEDIMENTATION IMPOUNDMENT

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
• A new 30-inch overflow that feeds back to the raw water pump station.
• A new parallel 30-inch PI bypass line and its interconnection to the existing raw water
piping.
• The new 48-inch PI effluent piping which carries on to the plants new rapid mix facility.
Hazen and Sawyer I Pre-Sedimentation Impoundment 9-11

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
lifetime compared to the existing PI effluent(Elevation 26 feet)a level much closer to the reservoir invert
(18 feet)where dissolved iron and manganese are more likely to have settled.
The preliminary design concept calls for earthen construction with on-site and imported materials.
Table-9-5 summarizes the design characteristics for an additional pre-sedimentation impoundment at the
plant. The new PI is to be constructed with an influent structure cast-in-place concrete similar in elevation
to that of the existing PI to allow gravity flow to the plant or back-feed to the raw water pump station. The
effluent structure should match the recommendation for the proposed upgrade to the existing
impoundments effluent. Figure 9-6 illustrates the physical layout of the new PI, located just west of the
existing 63 MG impoundment. Liner options for the impoundment include either fiber-reinforced concrete or
40 mil linear low-density polyethylene (LLDPE). Fiber-reinforced concrete is a readily available and durable
option, but is prone to cracking and also requires geomembrane liner due to the permeability of the
concrete. If installed alone, the LLDPE liner limits access and is prone to damage during cleaning.
Therefore, a sacrificial soil layer is recommended to cover the liner for protection. Benefits to the LLDPE
liner include impermeability along with its higher durability and cost favorability over PVC. At an additional
cost, Fabriform may be added to internal side slopes through the impoundment's anticipated drawdown
range to protect against erosion.
Table 9-5: Design Characteristics of New Pre-Sedimentation Impoundment
Parameter Units Design Criteria
Capacity MG 71
Interior slope (H:V) ---- 2:1
Exterior side slope (H:V) ---- 3:1
Liner option 1 ---- Fiber-reinforced concrete
Liner option 2 ---- 40 mil linear low density polyethylene
Invert elevation feet 18
Overflow level feet 51
Typical drawdown range feet 0—7
Influent elevation (top) feet 21
Effluent elevation (top) feet 41.0
'Elevations are reported relative to mean sea level.
A second PI requires new yard piping including a 30-inch inlet and 48-inch outlet line, similar to the existing
impoundment(with exception to outlet size). Figure 9-6 provide the new yard piping necessary to
accommodate the new PI, including:
• A new parallel 30-inch raw water line that conveys water to the PI.
Hazen and Sawyer I Pre-Sedimentation Impoundment 9-10

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
9.3 Storage Volume Considerations
Off-stream storage provided by the 63 MG PI offers a short-term water supply option in the event of a
nearby spill or contamination of the Tar River. Impoundment volume was crucial during the Hurricane
Matthew event and may be used again in similar events such as railcar or tanker truck spills. Additional off-
stream storage would further enhance the resiliency of raw water supply to the plant, therefore allowing
GUC staff to maintain treatment operations. The qualitative benefits of additional raw water storage would
be realized regardless of the planned capacity.
There is available footprint west of the existing PI for an additional impoundment. A preliminary layout was
developed for a second PI and the site will accommodate up to a 71 MG impoundment. Table 9-4
summarizes the additional detention time acquired through a second Pl. The benefit of additional storage is
apparent at future plant capacities as days of raw water storage in a single impoundment are noticeably
less than that observed with the additional PI.
Table 9-4: Hours of Storage Based on Back Feed to Raw Water Pump Station in New Pre-
Sedimentation Impoundment
Existing + New P1
WTP Capacity Raw Water Flow Existing PI (63 MG) (134 MG)
(mgd) (mgd) Days of Storage Days of Storage
Average day demand 4.3 9.2
22.3
Max day demand 2.8 6.0
32 Average day demand 3.0 6.4
Max day demand 1.9 4.2
38 Average day demand 2.5 5.4
Max day demand 1.6 3.5
45 Average day demand 2.1 4.6
Max day demand 1.4 3.0
9.4 Existing Impoundment Upgrades, Preliminary Design Criteria, and
Layouts
As a minimal design upgrade to the existing pre-sedimentation impoundment it is recommended that the
effluent structure be raised to an elevation of 41 feet, approximately 3 feet below the typical drawdown
minimum. Raising the outlet structure allows for an additional buffer to the water quality concerns described
in Section 9.2. Pulling water from a mid to high reservoir strata (below the epilimnion and above the
bottom), provides opportunity to intake the best available water quality. Although, the raised outlet may not
provide additional benefit during impoundment overturn, which coincides with seasonal changes in North
Carolina. This is due to mixing during stratification, which increases the likelihood of uniform water quality
in the PI from top to bottom. However, the raised structure should intake higher quality water over its
Hazen and Sawyer I Pre-Sedimentation Impoundment 9-9

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
0.18 —
Secondary MCL
0.16 —
: :: i
.
. ' I
11(
0.1 -
J
c0.08 �§ Ilk
0.06 4
0.04 —
0.02
06/02/14 06/12/14 06/22/14 07/02/14 07/12/14 07/22/14 08/01/14 08/11/14 08/21/14
-Tar River —Impoundment Settled —Combined Filter
Figure 9-5: Total Manganese During Summer 2014
Hazen and Sawyer I Pre-Sedimentation Impoundment 9-8

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
0.16 -
Secondary MCL
0.14 -
0.12 -
0.1 -- 0.08 i A
-
c
T
411111116"
. . . . . . . . ....
0.04 -
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01/03/11 01/09/11 01/15/11 01/21/11 01/27/11 02/02/11 02/08/11 02/14/11 02/20/11 02/26/11
Tar River --- Impoundment Settled --Combined Filter
Figure 9-4: Total Manganese During Winter 2011
Hazen and Sawyer 1 Pre-Sedimentation Impoundment 9-7

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
1.4
Secondary MCL
1.2 —
1
J
E 0.8
C -_
v 0.6 —
N
0 0.4 —
0.2
egi
9/1/11 9/4/11 9/7/11 9/10/11 9/13/11 9/16/11 9/19/11 9/2 2/11 9/2 5/11 9/28/11
—Tar River —Impoundment —Settled —Combined Filter
Figure 9-3: Total Manganese During Hurricane Irene(2011)
Hazen and Sawyer I Pre-Sedimentation Impoundment 9-6

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
0.50 -. T r - ,_..
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11/18/10 6/6/11 12/23/11 7/10/12 1/26/13 8/14/13 3/2/14 9/18/14
—Tar River—Impoundment ----Settled —Combined Filter
Figure 9-2: Historical Total Manganese (2010-2014)
Hazen and Sawyer I Pre-Sedimentation Impoundment 9-5

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
levels in the Tar River. Several cases where high manganese trends have been observed in the past were
evaluated, to include Hurricane Irene in fall 2011, the winter 2011, and the summer of 2014.
The highest historical manganese levels were recorded duringHurricane Irene in September 2011 (refer to
9 9 P
Figure 9-2). Manganese levels in the Tar River peaked near 1.8 mg/L. After the hurricane, manganese
levels in the PI remained above Tar River concentrations for more than two weeks, indicative of
manganese release from the PI. However, despite these higher concentrations leaving the PI, downstream
treatment processes were effective in managing finished water manganese concentrations below the MCL.
After Hurricane Irene, manganese levels in the Tar River recovered, declining back to typical levels by
October 2011. However, manganese levels in the PI effluent often exceeded Tar River levels through
February 2012 (Figure 9-3). During the winter of 2011, thermal stratification would not have been the likely
cause for manganese release. Particulate manganese collects in the sediment pool of the PI. The PI had
not been dredged in years and sediment accumulation was evident. It is possible the sediment layer had
accumulated to the point that scouring of the sediment layer occurred and conveyed solids and
manganese deposits into the WTP. GUC staff dredged the PI in the spring of 2016.
Figure 9-4 illustrates a comparison of high total manganese levels recorded in the summer of 2014. Total
manganese levels in the PI were commonly found above that in the Tar River. GUC staff does not feed a
pre-oxidant in the PI inlet. The current strategy is to feed sodium permanganate in the PI effluent when
manganese levels in the PI effluent exceed 0.07 mg/L.
Although there are incidences of raw water manganese excursions in the raw water, these cases typically
last for relatively short periods. Total manganese levels in the PI effluent exceed levels in the PI inlet
approximately 10 to 15 percent of the time, except during Hurricane Irene. Periodic dredging may help
control particulate manganese from carrying over into the WTP. Dissolved manganese levels in the PI
effluent exceed the Tar River concentrations only 4 percent of the time when the Hurricane Irene event is
ignored. Therefore, there is not strong evidence that manganese release is regularly occurring in the Pl.
A review of manganese levels in the finished water reveal that GUC staff has experienced one exceedance
of the secondary limit. The current treatment practices of raw water sodium permanganate feed (during
periods with high manganese concentrations) and sodium hypochlorite feed to filter influent have effectively
controlled manganese levels. Given this historical WTP performance, there does not seem to be a strong
driver for de-stratification of the PI through aeration techniques if the filters continue to operate in abiotic
mode (refer to Sections 12 and 13). Data shows pre-filter chlorine addition is a robust manganese barrier
even under extreme water quality conditions. Since the data does show higher manganese in PI effluent on
some occasions, additional manganese control methods may be warranted with biological filtration.
Aeration or other de-stratification strategies should be re-considered if BAF conversion is implemented in
the future.
Despite the filter mode of operation selected for the WTP, routine monitoring of sediment build-up within
the PI is recommended. Also, a routine dredging program will preserve the volume of the PI, thus
enhancing settling and mitigating the risk of high manganese and turbidity carryover into the WTP.
Hazen and Sawyer I Pre-Sedimentation Impoundment 9-4

Preliminary Engineering Report
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Greenville Utilities Commission
In the back-feed configuration to the raw water pump station, the drawdown range of the PI is
approximately 30 feet from the overflow down to the top of the influent structure (refer to Figure 9-1). Due
to the increased range and volume, this available storage is significantly higher, referenced in Table 9-3.
The back-feed configuration provides for risk management by allowing for short-term shutdowns of the Tar
River intakes in the event of intake maintenance or failure, or to avoid spills or other raw water
contamination events.
In October 2016, Hurricane Matthew struck the state of North Carolina causing flooding events across the
region and resulted in challenging Tar River water quality for several days thereafter. Over this timeframe,
a pair of bulk fertilizer storage tanks at Southern States Chemical in Princeville, NC were found empty. This
facility is located along the Tar River, upstream of the WTP intake. Fortunately, the plant manager at
Princeville facility had drained the tanks as a precaution before the hurricane, but the message did not
reach GUC in a timely fashion. As a precaution, GUC staff shutdown the plant's intake relying on the off-
stream storage volume of the PI. Impoundment drawdown reached approximately 5 feet, a level just 2 feet
above the minimum operating range. EPA performed water quality tests to quantify nitrate and phosphorus
levels in the river. Although high levels were not found in the water, this event identified the potential
vulnerability of GUC's raw water supply to contamination as well as the value of off-stream storage to
maintain treatment operations.
Table 9-3: Days of Pre-sedimentation Impoundment Storage Based on Back Feed
to Raw Water Pump Station
WTP Capacity Raw Water Flow Existing PI
(mgd) (mgd) Days of Storage
Average day demand 4.3
22.3
Max day demand 2.8
32 Average day demand 3.0
Max day demand 1.9
38 Average day demand 2.5
Max day demand 1.6
45 Average day demand 2.1
Max day demand 1.4
9.2 Water Quality Considerations
Manganese is present in the Tar River although at fairly low levels typical of riverine sources. Manganese
data throughout the WTP were evaluated to assess whether the PI experiences thermal stratification and
manganese release in the accumulated sediments. Historical total manganese data from 2011 through
2014 average approximately 0.09 mg/L in the Tar River. Manganese concentrations in the PI effluent
average the same. There are incidences when the total manganese levels in the PI effluent exceed the
Hazen and Sawyer I Pre-Sedimentation Impoundment 9-3

Preliminary Engineering Report
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• Back-feeding Method—raw water is conveyed through the PI inlet structure back to the raw
water pump station and then pumped through the raw water bypass to the rapid mix. In this
configuration, raw water could not also be withdrawn from the Tar River.
The available storage in the PI is dependent on the withdrawal configuration. During typical operations, PI
drawdown is limited to a range of approximately 7 feet(refer to Figure 9-1) measured from the PI overflow
elevation. Due to excessive headloss through raw water piping downstream of the PI, the drawdown is
limited when raw water flows are 18-mgd or greater. The hours of storage available under average day and
max day demand scenarios for the current and future treatment capacity options are provided in Table 9-2.
TOP 53.0
OVERFLOW 51.0
TYPICAL WITHDRAWAL DEPTH RANGE=7'
EFFLUENT(TOP) 26.0
21.0 INFLUENT(TOP) '44111111111111111.1.*-
INVERT 18.0
MAXIMUM WITHDRAWAL DEPTH
mu TYPICAL WITHDRAWAL DEPTH
SEDIMENT STORAGE DEPTH=8.0'(INVERT TO EFFLUENT);3.0'(INVERT TO INFLUENT)
Figure 9-1: Notable Elevations for the Pre-Sedimentation Impoundment
Table 9-2: Hours of Pre-sedimentation Impoundment Storage Based on Typical
Operations for Gravity Drawdown Method
WTP Capacity Raw Water Flow Existing PI
(mgd) (mgd) Hours of Storage
Average day demand 32.7
22.3
Max day demand 21.2
32 Average day demand 22.8
Max day demand 14.8
Average day demand 19.2
38 Max day demand 12.5
Average day demand 16.2
45
Max day demand 10.5
Hazen and Sawyer I Pre-Sedimentation Impoundment 9-2

Preliminary Engineering Report
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9. Pre-Sedimentation Impoundment
9.1 Summary of Existing System
The existing pre-sedimentation impoundment(PI) is a 63 MG reservoir that was constructed in 1981. The
PI provides preliminary solids settling and assures relatively consistent raw water quality that is conveyed
to the treatment process. Relevant elevations and design characteristics of the PI are listed in Table 9-1
and graphically represented in Figure 9-1. The PI serves two main functions as follows:
• Pre-settling —reduces raw water turbidity and buffers against water quality excursions (e.g.,
rain events, hurricanes, etc.).
• Off-stream storage—provides risk mitigation against spills/contamination events upstream
in the Tar River and failures, shutdowns, or planned maintenance activities for the intake
screens.
The PI serves as a buffer, dampening turbidity fluctuations in raw water supply from the Tar River. This
provides a more consistent incoming raw water quality and limits frequent changes to raw water chemical
doses. The PI also tends to buffer influent manganese concentrations by settling primarily particulate
manganese. Soluble and colloidal manganese are typical treated via chemical oxidation within the WTP.
Table 9-1: Design Characteristics of the 1981 Pre-Sedimentation Impoundment
Parameter Design Criteria
Capacity 63 MG
Slope (H:V) 2:1
Top Elevation 53 feet
Overflow Elevation 51 feet
Invert Elevation 18 feet
Typical Drawdown Range 0—7 feet
Influent Elevation (Top) 21 feet
Effluent Elevation (Top) 26 feet
Liner Flexible geomembrane
'Elevations are reported relative to mean sea level.
In the event off-stream storage is needed, the PI can be used as a short-term supply solution. The PI can
be operated in two configurations:
• Typical Operations—raw water from the PI flows by gravity to the rapid mix facility.
Hazen and Sawyer I Pre-Sedimentation Impoundment 9-1

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1 4U-0 GREENVILLEPHASE 1 WTP UTILITIMPROVEMIES COMMISSION
FIGURE 8-6
RAW WATER PUMP STATION
Hazen PIPING LAYOUT

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
factory to configure 4-inch internal air burst piping to the screen with a 6-inch flange connection.
Alternatively, a set of four new screens, equipped with the required piping for air burst, eliminating the need
and freight costs to ship the existing screens to the factory. The 27-inch screens, which have existing air
burst flanged connections, will not require retrofit or replacement. Per manufacturer recommendations, the
air burst system would include a 40 HP rotary screw compressor/receiver system located in the nearby
storage building adjacent to the raw water pump station. Piping for the system requires four 3-inch lines to
the 27-inch screens and four 6-inch lines to the 42-inch screens with stainless steel construction and
remote-controlled lug-style butterfly valves to facilitate air conveyance to the individual screens.
To complete the air burst line installation, cofferdams would be constructed around the screens to the
shoreline to allow dry conditions to trench the stainless steel piping. A dewatering system would also be
necessary to keep up with any leakage through the cofferdam walls. The height and bury of the cofferdam
walls should accommodate the maximum river level anticipated during construction. Wall height has a
direct impact on costs and should be carefully evaluated in a final design effort to ensure adequate
protection is provided during construction activities. Two cofferdam installations, one for each set of four
screens, would allow each group of screens to be taken off-line separately maintaining a portion of the
overall intake screen capacity during the completion of this work. If the existing 42-inch screens are
retrofitted, consideration should be given to disconnecting the screens by a diving subcontractor to prevent
the need to maintain the cofferdam arrangement around the newer set of screens for several weeks.
Factory retrofit of the screens is estimated at four weeks exclusive of shipping. The capital costs estimated
to complete this work is over$2 million due to the excessive installation costs associated with the
cofferdam system. An air burst is not recommended for installation at the WTP intake due to the cost and
the limited effectiveness of the air burst system to address the river sediment issue.
Hazen and Sawyer I Raw Water Pumping and Transmission 8-13

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
headloss formation. As the header exits the pump station into the yard, the piping will split between the
existing 30-inch raw water line and a new parallel 30-inch raw water line.
Construction sequencing for replacement of the existing header involves first acquiring access to the
piping. An access hatch may be installed in the pump room floor adequate in size for removal and
replacement of the larger 42-inch piping and fittings. The centerline of the new header piping will be raised
above the existing pump discharge header and supported from the valve and piping room floor. The
elevated location of the discharge header will accommodate individual, upsized pump and discharge piping
replacement efforts in the future. As the header replacement process will result in temporary loss of
pumping capacity at the station, it should be coordinated along with the wet well modifications.
Coordinating these construction activities concurrently into one construction effort will eliminate the need to
call upon the need of a temporary pumping system twice. The estimated construction time for the header
replacement is equivalent to that of one wet well upgrade (e.g., 3 weeks).
As an alternative option. during final design planning. Hazen will compare phased upgrade scenarios. The
scenarios will consider the hydraulic limitations posed by the transmission piping as plant capacity
increases, and the necessary pumping configurations needed to meet those constraints. The extent of
transmission upgrades will have significant impact on the raw water pump upgrades, which are also closely
tied to the electrical system upgrades. This alternative analysis will provide upgrade options with cost
effective solutions for near term raw water pumping needs.
8.6 Raw Water Intake Screen Air Burst
GUC currently has a sand eductor system in place to account for potential sand build-up in the raw water
pump station wet well. The sand eductor system is a removal technique designed to pump wet well
sediment accumulation back into the river. Currently, there are no foreseen modifications to the eductor
feature to maintain sediment control at the pump station. There is also a backflush system, designed to
flush the raw water intake piping and screens by pushing flow back through the intake piping via a
connection to the raw water pump discharge header.
GUC staff have documented issues with sediment and debris build-up around the intake screens in the Tar
River. To assist with potential clogging, air burst capabilities were considered for the screens. Air burst may
provide localized cleaning of debris accumulation and attachment to the screen periphery by conveying
high pressure air bursts via air lines out to the individual screens on a pre-determined schedule. However,
the system is not a viable technique for continuously clearing and maintaining substantial sediment
accumulations surrounding the intake screens as observed in the river. Routine dredging around the intake
screens is recommended to prevent excessive sediment accumulation and maintain the hydraulic capacity
of the screens. Air burst would be considered a supplemental strategy to assist with maintaining this
capacity.
The existing screens located in the river do not have air burst capability. To accommodate air burst, the
newer 42-inch screens will require retrofit or replacement as these screens are not currently configured to
accept air lines. The retrofit option involves removing the four screens from the river for shipment to the
Hazen and Sawyer I Raw Water Pumping and Transmission 8-12

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 8-5: Summary of Existing Firm Raw Water Pump Performance at Limiting Conditions
Raw Water Pump Flow(mgd)
Limiting Firm
WTP Number and Pressure Pumping
Capacity QRWPS Size of Raw Head Pump Pump Pump Pump Capacity
(mgd) (mgd) Water Main(s) Constraint No. 1 No. 2 No. 3 No.4 (mgd)
22.3 22.3 One 30-inch Rapid Mix N/A 9.1 8.8 5.8 1 23.7
Pump is operating outside of efficiency range.
Table 8-6: Proposed Firm Raw Water Pumping Configurations at Future Plant Capacities
Raw Water Pump Flow(mgd)
WTP Number and No. of
Capacity QRWPS Size of Raw Required Firm Pump Pump Pump Pump New
(mgd) (mgd)1 Water Main(s) TDH (feet)2 Capacity No. 1 No. 2 No. 3 No.4 Pumps
32 35 Two 30-inch 73.0 35 7.6 3 13.7 4.5 13.7 4 13.7 4,5 0
38 41 Two 30-inch 80.5 41 13.7 13.7 13.7 13.7 4
45 49 Two 30-inch 92.1 49 16.3 16.3 16.3 16.3 4
QRWPS is accounting for an additional 8 percent of raw water flow pumped to the Pl. based off historical raw water flows.
2 Limiting pressure head constraint is the Pre-Sedimentation impoundment for future raw water flows.
3 Pump does not require modifications.
°Pump requires impeller retrofit to meet design requirements.
5 Pump requires a motor upgrade to 250 HP for the plant expansion to 32 mgd.
At the 32 mgd scenario, Hazen proposes an impeller retrofit for raw water pump No. 2, raw water pump
No. 3, and raw water pump No. 4 to accommodate the increased demand. In addition to an impeller trim,
raw water pumps No. 2 and No. 4 should be upgraded to 250 HP motors. Other pump components may
require replacement considering age and operating conditions. However, the cost associated with minor
pump improvements will be less than an entire pump replacement.
At a 38 mgd scenario, all pumps must be replaced with four new 13.7 mgd vertical turbine pumps. Four
16.3 mgd pumps are needed to meet the 45 mgd capacity condition. For all future pumping scenarios,
installing vortex suppression is recommended to address cavitation concerns in the wetwell.
Increasing the capacity of the raw water pumping configuration is coupled with upsizing the current
discharge piping and header inside the raw water pump station. The recommendation is to increase the
individual pump discharge piping and valves associated with the new pumps to 24-inch pipe. The raw
water pump station discharge header piping should be increased to 42-inch to reduce velocity and
Hazen and Sawyer I Raw Water Pumping and Transmission 8-11

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
8.4 Raw Water Transmission
At the increased raw water pump station capacity scenarios of 35 mgd (e.g., 32 mgd plant capacity) to
49 mgd (e.g., 45 mgd plant capacity), velocities in the current raw water pump station discharge header will
range from 11.0 ft/s to 15.5 ft/s, respectively. Pipe velocities within a 6.0 ft/s to 9.0 ft/s range will limit
potential cavitation and/or erosion issues and reduce the motor size required for upgrades to the raw water
pumping infrastructure. The hydraulic analysis demonstrates that the 30-inch raw water transmission main
and 30-inch bypass line conveying raw water from the pump station to the WTP will also exhibit velocities
that exceed the recommended criteria. Therefore, addition of a second 30-inch raw water transmission and
bypass line will eliminate these identified concerns at and above 32 mgd. Figure 8-6 illustrates the
immediate piping around the raw water pump station, which is continued in the pre-sedimentation
impoundment site plans.
8.5 Raw Water Pumping
The hydraulic modeling and technical evaluation demonstrated that improvements are necessary to
resolve the raw water pump station and transmission main challenges for the plant expansion. The
recommended improvements include the following:
• Improve the wetwell design.
• Retrofit or replace pumps.
• Install pump vortex suppression devices.
• Conduct a detailed wetwell model.
• Upsize transmission main piping.
Raw water pump performance was evaluated at the existing WTP capacity as well as future plant capacity
increments of 32, 38, and 45 mgd. The evaluations consider the pump discharge pressure requirements at
each of the future flow capacity increments. The results of the evaluation are summarized in Table 8-5. As
plant flow increases from 32 mgd to 45 mgd, greater pumping capacity is required. The pump performance
evaluation considered conveyance to the existing pre-sedimentation impoundment or directly to the plant's
existing and new rapid mix facilities via bypass operations. The discharge destination that restricted flow
output is also provided in Table 8-5.
Recommendations for pumping upgrades at future capacities were developed leveraging the use of
existing pumping infrastructure where possible and replacing as needed. In several cases, a pump can
remain in service via minimal alteration (e.g., an impeller retrofit) rather than the purchase of a new pump.
Consideration was given to the continued use of raw water pump No. 1 due to its recent upgrade in 2012
relative to the other existing pumps, which may have received increased wear over their lifespans. The
pumping options and required heads for each capacity scenario are summarized in Table 8-6.
Hazen and Sawyer I Raw Water Pumping and Transmission 8-10

Re
port
Engineering
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Existing RWPS RWPS Wet Well
Wet Well Upgrades
Wet Well
No.1
Wet Well
No.2
Wet Well
No. 1
Wet Well
No.2
Exiting wet
well baffle Removal of
Existing 30-inch walls baffle wall
inlet piping New 42-inch
inlet piping
and 42-inch tee
Figure 8-5: Proposed Improvements to the RWPS Wet Well and Inlet Piping
Hazen and Sawyer I Raw Water Pumping and Transmission 8-9

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
associated with either well could be paired with raw water pump and common pump discharge header
modifications. Modifications to wet well No. 2 would occur in a similar construction sequence. In this
scenario, available capacity to wet well No. 1 significantly decreases. With only two 27-inch screens in
service (12 mgd total), a temporary pumping system is more than likely necessary to provide sufficient
intake and pumping capacity to the plant. Pre-sedimentation storage capacity is a beneficial emergency
back-up should the need arise during construction. If a second pre-sedimentation impoundment is
constructed, then it is recommended that intake modifications be completed thereafter.
RWP-1
RWP-2
Velocity
Plano Z
RWP-3
50 C C)
RWP-4
45 C L%
40
35
- 1 �
30411.
�• /' �
2 5 ,► � '
20 y`mo w
f : -
1ff
s^-1)
Figure 8-4: CFD Model of Potential RWPS Wet Well Upgrades at 38 mgd and -8.0 WSE
Hazen and Sawyer I Raw Water Pumping and Transmission 8-8

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
recommendation of 1.5 ft/s set by Hydraulic Institute Standards. A 42-inch tee capping the end of these
inlet pipes resolves the concerns of the jetting effects as raw water is discharged into the wet well.
Removal of the baffle wall in front of the pumps mitigates low submergence concerns in the wet well, which
sets the new minimum water level in the wet well at-6.5 feet, a level determined by the minimum
submergence of the pumps. Figure 8-5 depicts the proposed modifications to the wet well baffle wall and
inlet piping before and after construction. Table 8-4 provides a summary of the wet well WSE and entrance
velocities considering the piping and wet well modifications. A physical model study is recommended as
part of the final design effort to confirm problem areas and solutions to the limitations of the existing wet
well configuration.
Table 8-4: Raw Water Pump Station Wet Well Water Surface Elevations and Entrance
Velocities at Low River Level with Recommended Wetwell and Piping Modifications
WTP Tar River Sump Floor Calculated Pump Bay
Capacity QRwPs Minimum WSE Elevation Limiting WSE Wet Well Velocity
(mgd) (mgd) (feet) (feet) (feet) WSE (feet) (ftls)
32 35 -1.0 -11.50 -6.50 -3.67 0.39
38 41 -1.0 -11.50 -6.50 -4.63 0.61
45 49 -1.0 -11.50 -6.50 -6.15 2 0.88
Limiting WSE based on pump minimum submergence assumption of 60 inches.
2 Assume baffle wall is no longer WSE limiting factor after modification.
Construction sequencing for upsizing to 42-inch wet well inlet piping has been assessed to ensure
continuous plant functionality and operation. To access the piping, the 60-inch screen adjacent to the pump
station should be temporarily removed to allow for excavation and construction. The high intake screen
(10.0 feet MSL) is positioned directly above the existing 30-inch Wet Well No. 2 intake piping (centerline -
7.0 feet MSL). A coffer cell should also be installed in the work area to allow for excavation and
construction. With the minimum river level being -1.0 feet MSL, the work area would typically be
submerged.
The raw water wet well consists of two separate compartments (wet well No. 1 and wet well No. 2)with a
normally open sluice gate available for isolation purposes. Modifications can be made to wet well No. 1 by
closing valves in the common intake header and the sluice gate, isolating the wells. The pump station will
draw from wet well No. 2 independently, fed a capacity of 57 mgd 6 screens and
then by screening P Y 9 ( ),
limited by a nominal pumping capacity of 24 mgd. A temporary pumping system is recommended as a
precautionary measure to ensure reliable pumping capacity to the WTP. The temporary system could draw
raw water from the Tar River and convey flow directly to the pre-sedimentation impoundment.
After wet well No. 1 has been dewatered, inlet piping can be removed, the wet well wall cored for the
upsized inlet piping, and set in concrete to cure. The new piping will be tested for leaks prior to being
placed back into service. It is estimated that the overall process will take three weeks. Construction
Hazen and Sawyer I Raw Water Pumping and Transmission 8-7

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
very
Streamone Inlet [ft a^.1)
IIIIIIIIMV' ARM
CP (:) ,o ,`' do 4) 4 4) 1.( 4)
1
! \,, I I _ ,`i ,
n '`,''''I' ' 1 '', !'f'`\,.' ''''i,,14:: "'''-r-.:.='i,,r71\,^4't\t'I
it 1
kstlr • - -l_ _
/
Figure 8-3: CFD Model of the Existing RWPS Wet Well at 41- MGD (Y-axis Pathline Flow)
Table 8-3: Raw Water Pump Station Wetwell Water Surface Elevations at Low River Level
Tar River Wetwell Baffle Calculated
WTP Capacity Minimum WSE Wall Elevation Wetwell WSE
(mgd) QRwPs(mgd) (feet) (feet) (feet)
32 35 -1.0 -5.50 -2.41
38 41 -1.0 -5.50 -5.01 1
45 49 -1.0 -5.50 -6.69 1
WSE less than 1 foot above baffle wall elevation.
The hydraulic and CFD modeling resulted in recommendations for improvements to the existing wet well
design to accommodate future plant capacity. Figure 8-4 provides an illustration of the velocity in the raw
water pump station wet well at WSE -8.0 feet at 38 mgd plant capacity conditions. Replacing the existing
30-inch pipe into each wet well compartment with 42-inch pipe will resolve the excessive entrance
velocities at higher flow rates. Pump bay velocities for each capacity scenario meet the maximum velocity
Hazen and Sawyer I Raw Water Pumping and Transmission 8-6

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
The hydraulic model indicated that the hydraulic losses between the wet well and intake screens will be
significant at future plant flows greater than 38 mgd. The existing pumps are encompassed in a can type
well with a front baffling wall at a top elevation of-5.5 feet. With the current 30-inch inlet piping
configuration, hydraulic losses may inhibit the water surface from rising above the baffle wall preventing
water from reaching the pump suction. Table 8-3 documents the calculated wet well WSE at the different
pump station capacities.
RWP-1
RWP-2
velocity RWP-3
Streembne Inlet
5 0 RWP-4
4.5
4.0 L..
3.5
3.0 t�
2.5 s
2.0 f ) ✓ 4V. ,.i.
15 „Aa ~i.
m
05
0.0
Ul 5"-11
Figure 8-2: CFD Model of the Existing RWPS Wet Well at 41 mgd (Isometric Pathline Flow)
Hazen and Sawyer I Raw Water Pumping and Transmission 8-5

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
8.2 Hydraulic Evaluation
Hydraulic analyses were conducted to evaluate raw water pumping and transmission needs at current and
future plant capacities. The list of assumptions used to develop the hydraulic model for the raw water pump
station is as follows:
• Tar River at low-level MSL of-1.0 feet.
• Pre-sedimentation impoundment at maximum WSE of 51.0 feet.
• Existing and new rapid mix at maximum WSE of 40.5 feet and 41.6 feet,
respectively.
• Raw water flows account for an 8 percent differential between historical raw water
flows to the pre-sedimentation impoundment(QRwPs) and historical raw water flows
from the pre-sedimentation impoundment into the plant.
O 32 mgd plant capacity = QRWPS of 35 mgd raw water pumping capacity.
o 38 mgd plant capacity = QRWPS of 41 mgd raw water pumping capacity.
o 45 mgd plant capacity= QRWPS of 49 mgd raw water pumping capacity.
• Hazen and Williams coefficient(C factor) of 110.
• Intake screens at 36 percent open area.
• All screens in operation except high river level screen.
• Assume one pump out of service to simulate firm capacity scenario.
• Existing 4-foot by 4-foot sluice gate is open between the wet wells.
8.3 Raw Water Pump Station Wetwell
Raw water approaches the pump station wet well via intake piping from each of the screens. Flow
converges in a header, which enters wet well No. 1 and wet well No. 2 through two 30-inch lines at
centerline elevation -7.0 feet. The existing 30-inch wet well intake piping will experience velocities between
5.39 ft/s to 7.54 ft/s at 35 mgd (32 mgd plant capacity) and 49 mgd (45 mgd plant capacity), respectively.
The corresponding entrance velocities exceed Hydraulic Institute Standards, which recommends a
maximum approach velocity of 1.5 ft/s. In conjunction with high entrance velocities, computational fluid
dynamic(CFD) modeling at the limiting conditions demonstrated vortex formation and pump swirl in the
wet well. Illustrations of CFD modeling at a 38 mgd plant capacity in the existing wet well are provided in
Figures 8-2 and 8-3.
Hazen and Sawyer I Raw Water Pumping and Transmission 8-4

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' -40
� PHASE 1 WTP IMPROVEMENTS
v.
GREENVILLE UTILITIES COMMISSION
FIGURE 8-1
o SITE PLAN FOR INTAKE
Hazen SCREENS AND ASSOCIATED
i. YARD PIPING

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 8-2: Summary of Design Parameters for Existing Raw Water Pumps
Year Installed
or Last Design Flow Design Motor Efficiency at
Pump Upgraded Rate Head Horsepower Design Point
Raw
pump water
2012 12.0 mgd 56 feet 150 86%
No.Raw water 2000 12.0 mgd 56 feet 150 83%
pump No. 2
Raw water 1993 12.0 mgd 56 feet 150 86%
pump No. 3
Raw water 1981 12.0 mgd 50 feet 150 84%
pump No.4
Hazen and Sawyer I Raw Water Pumping and Transmission 8-2

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
8. Raw Water Pumping and Transmission
8.1 Existing Facility Evaluation
Raw water for the Greenville WTP is withdrawn via nine stainless steel wedgewire intake screens located
in the Tar River. The original four tee screens, constructed in 1980, are located at-3.4 feet mean sea level
(MSL). Four additional tee screens were installed in 2011 at-7.0 feet MSL and are located just
downstream of the 1980 screens. The ninth screen, added in 2004, is located adjacent to the raw water
pump station at an elevation of 10.0 feet MSL and is used during high river level conditions. Design
parameters of the existing intake screens are summarized in Table 8-1. Figure 8-1 illustrates the site plan
arrangement of the intake screens and associated yard piping. Under normal plant procedures, eight of the
screens are used to include all of the 27-inch and 42-inch screens. The nominal capacity of these intake
screens is 69 mgd, which is sufficient for all future demand scenarios under consideration. Therefore, a
detailed evaluation of the intake screens was not included in the scope of this PER.
During typical operations, raw water is conveyed to the pump station wet well via gravity by four 30-inch
lines with each set of four screens feeding two lines. Raw water is drawn from the pump station's wet well
via four vertical turbine pumps and discharged to the pre-sedimentation impoundment or to the rapid mix
facility via a bypass line. The pumps discharge into a 30-inch common header that directly connects to the
inlet of the pre-sedimentation impoundment. Bypass piping (e.g., 30-inch) directs raw water around the pre-
sedimentation impoundment and into the WTP. The raw water pump station is designed to accommodate
four pumps. Design criteria for the existing raw water pumps is summarized in Table 8-2.
Table 8-1: Summary of Existing Intake Screen Design Criteria
1980 Intake 2011 Intake
Parameter Screens 2004 Intake Screen Screens
Number of screens 4 1 4
Rated capacity of each 4,167 gpm 8,333 gpm 7,818 gpm
screen (6 mgd) (12-mgd) (11.25-mgd)
Maximum slot velocity at 0.50 ft/s 0.50 ft/s 0.50 ft/s
design flow
Slot opening size 0.20 inch (5 mm) 0.04 inch (1 mm) 0.04 inch (1 mm)
Screen diameter 27 inches 60 inches 42 inches
Inlet pipe Two 30-inch pipes One 24-inch pipe Two 30-inch pipes
Airburst flange connections Yes No No
Hazen and Sawyer I Raw Water Pumping and Transmission 8-1

INTIRMEDLMF OZONATED FILTER EFFLUENT FINISHED
COMMONCDmON OZONE WATER CHANNEL FILTERS CHANNEL ClFI1RWHL PS CIFMWELL WATER PS
ALT I EXPANSION' 3).9 17.0 37.2 25.9 21.0 54.0 50.0
ALT2 EXPANSION' 30.0 37.4 16.9 26.1 210 54.0 N.5
FUTURE DEMAND' 11.0 37.0 16.9 16.3 23.0 50.0 46.1
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RAM FIL117.011001,TIP
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CONDITION CM_ 'Tr:``,'ROT
®_=EMIMM
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- r �_�� NOTES:
m .... 65 E 1.BASED ON AVERAGE TM RIVER LEVELS.
A so 2.AsoE;ni" IN BASINS,N:aBASSw 99 FEET,
S Hs EOXIISSTI9G OZONE INFLUENT PIPING,MAXIMUM
NE INFLUENT VALVE OPEN DM,
CONTACTORS AND IO FILTERS.FL
i THROUGH w LSAroRS,zi SPLIT
5 THROUGH EXISTING.PERw
i "• l SEDIMENTAT10N�BASIN WEIR AT BASINS,
FEET,42'
nNA if.9 as OZONE INFLUENT PIPING,MAXIMUM OZONE
TOC 41311 INFLUMT A OZONE
CONTACTORS VANDP12 FILTERS,FLOW SPLIT
ao
ZONGD THRoucN wPFRn1l5AT0R5,1B MGD
TMR HIGH EXISTING.
G - - ® U , mvisavc 'l A.ASSUMES 65EDIMENTATON BASINS,
' SEDIMENTATION WIN WEIR AT 19.0 FEET,01
w T PIPING,MAXIMUM INFLUENT
K rirrirririiiriiririrrirrr 00r 00 rr PPIHc l0 VAL.OPEN 11.,6 OZONE CONTACT°.AND la
���//�/�/�/�/�/�� �� 11 E FILTERS,FLOW SPLIT m MD THROUGH
iriilHiiiiillrlrl ID SLUERPULSATORS,15 MD THROUGH EXISTING.
■ ACHIEVE wsEL.WATER PIPING 1s NEEDED To
I cm vaTMD LARGER Rlw
_ ozOwTm a25.00 wT�P an
1 �'^�"� -"" U0 A NEW PROCESS ELEVATIONS ARE PRELIMINARY.
of EL MOO
74 Et --5 PHASE 1 WTP IMPROVEMENTS
m GREENVILLE UTILITIES COMMISSION
FILTRATION
gl
5 PARALLEL FILTRATION FIGURE 7-4
FUTURE FACILITY HYDRAULIC
Hazen PROFILE - CONTINUED

CONDITION PLAINT PAW WATER IMPOUNDMENTES MPIO F1DC BASIN SEDIMENTATION SEDIMENTATION
MAW PUMP STATION' IX BASIN 6 BASIN EFFLUENT
ALT 1 EXPANSION' 32.0 MNb 1.1 47.09 90.4 40.2 19.8 39.5 N
ALT 2 EXPANSION' 30.0 Fab 0.2 43.33 40.2 40.1 39.8 39.5 I
EMI.DEMAND. 460 MOD SO 31 40.1 40.0 39.8 39.4
65 1 1
H
1
OVERFLOW a 51.00
E.53.00
y _c Dw PRM
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-10
RAW WATER PRE-SETTLING
P PUMP STATION IMPOUNDMENT RAPID MIX FLOCCULATION SEDIMENTATION
comm. ANNLI
MIX SUPEAPUSATOL
1 ALT 1 E0V0610W 666 39.5
T3
ALT 2 EXPANSION' +La 39.6
FUTURE DEMAND. a.6 39.3$ is NOTES:
_.... I.BASED ON AVERR GE TAR RIVER LEVELS.
I SEDIMENTATION BASEIR AT INS,
3 5° 2 SEDIMENTATION
XISTING OIONNE INFLUENT PIPING,MAXIMUM
u
S9 OZONE INFLUENT VALVE DP.80%,4 OZONE
CONTACTORS,GH suPEz:uw:ORFs 221.0
THROUGH EXISTING.
ySUTLER SEDIMENTATION BASINS,
2 sm. _ WAWA SEDIMENTATION BASIN WEIR AT 398 FEET,9Y
TRIP,„%MAXIMUM OZONE
0 5 nen.s. SU.m nu9yl� INFLLIENT VALVE C OZONE
ONTACTORS AND Ii MLTERSOZONE FLOW
q� TNFaT VEMw - SPLIT
3 40 a Jan , 90MGU THROUGH SUPERMIISATORS,18 MGD
THROUGH EXISTING.
v — ASSUMES 6 SEDIMENTATION BASINS,
0
35 a SEDIMENTATION BASIN WEIR AT 39.8 FEET,41'
(�` � �� OZONE INFLUENT PIPING,MAXIMUM INFLUENT
VALVE OPEN 80%,6 OZONE CONTACTORS AND].
VI ..y_ --.. -....... 1_sn 6, FILTERS.FLOW SPLIT 30 MGD THROUGH
j --Is O. UPERWISATORS,15 MGO THROUGH EXISTING.
3 Is URGER PAW WATER PIPING IS NEEDED TO
i'._x ACHIEVE WSEL
y I 5.NEW PROCESS ELEVATIONS ARE PRELIMINARY.
3 S
P PHASE 1 WTP IMPROVEMENTS
RAPID MIX SUPERPULSATORS GREENVILLE UTILITIES COMMISSION
FIGURE 7-3 1
E. FUTURE FACILITY
Hazen
HYDRAULIC PROFILE

NOTES:
I.ASSUMES S SEDIMENTATION BASNS,°GSTING
S133114ENTAll ON BASIN EFFLUENT,MAXIMUM
OZONE INFLUENT VALVE OPEN MINE,3031E
CCNdnQN INTERMEDIATE °ZONATED FILTERSFILTER EFFLUENT CEAR LWELLRS CLEARWELL FINISHED CONTACTORS,AND 7 FILTERS
OZONE WATER°SW. CHANNEL WAIFS Pi SEDIMENTATION��
EXISTING RATED NO 3 SEDIMENTATION BASIN WEIR AT 39AFEET,
MODIFIUnONSN 37.9 l>.S 3lA ZSb 23.0 S60 52.0 MAXIMUM OZONE INFLUENT VALVE OPEN BOIS3
EXI STING WEDOZONE CONTACTORS,AND)FILTERS
MODI FICAn°.7 3,9 33/ x]A x 2M0 S10 SP
roam n.._.
a.. IR1A,WEWI
10CNSi
(.7
WC nJE 11.MO tine
Lai
flan a Ma ma
N
I a lli
Lsi
INTERMEDIATE CLEARWELL FINISHED WATER
•
OZONATION FILTRATION CLEARWELL
...............__._..__.__..._____.__._ ___...._.. PUMP STATION ..___..... PUMP STATION __—__._,__
S
31
i
F
C
1
I
I
2
8
d
2
PHASE 1 WTP IMPROVEMENTS
GREENVILLE UTILITIES COMMISSION
N
F. FIGURE 7-2
;15, EXISTING HYDRAULIC PROFILE
Hazen CONTINUED
R

NOTES:
1.ASSUMES 6 SEDIMENTATION BASINS,EXISTING
SEDIMENTATION BASIN EFFLUEM,MAXIMUM
OZONE INFLUENT VALVE OF.6046,3 OZONE
CONTACTORS.AND 7 FILTERS.
2.ASSUMES 6 SEDIMENTATION BASINS,
SEDIMENTATION BASIN WEIR AT 39.B FEET,
MAXIMUM OZONE INFLUENT VALVE OPEN 6046,3
OZONE CONTACTORS.AND 7 FILTERS.
CONomON PUNT RAW WAS PRE-SETTLING
RE-SE TLINT RAM FLOC SEDIMENTATION SEDIMENTATION
MOW PIMP STATION IX BASIN 6 •EDI�IN BASIN fFFLUELR
EXISTING RATED NO
MODIFICATIONS' 22.3 AGO 2.9 A9.9 10.3 A0.0 l9.) 39.7 '
EXISTING RATED
MODIFICATIONS' 22.3 MGD 2.B 30.0 40.4 40.2 39.B 39.1
65
m MARROW 6 sl.m - NRolI®Wua MAMMA
» vwOE.39.23
rf
>s ..
MMDT BRM� 1
MR�� M Aar �-
w N.
ano
1 IL"'"/
n aas
mIBC IBa _....._.... _...... _._.. _... __ __..._....
$ Is IOC
PA
Z 10
3 3
qi
B
i •
m'
• RAW WATER PRE-SETTLING RAPID MIX FLOCCULATION SEDIMENTATION
G PUMP STATION IMPOUNDMENT
9&
C
3e
d
$ PHASE 1 WTP IMPROVEMENTS
GREENVILLE UTILITIES COMMISSION
FIGURE 7-1
0
Hazen EXISTING HYDRAULIC PROFILE

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 7-1: Hydraulic Profile Scenarios at Various Expansion Phases
Flow Split(mgd) Critical Hydraulic Control Points Additional Modifications
Plant Flow Sedimentation Ozonated Channel Sedimentation Basin
(mgd) Basins SuperPulsators® WSE,feet' Effluent WSE 2 (feet) Required Details
22.3 9.7 37.8 39.5
32.0 - No ----
22.0 10.0 37.8 39.5
34.0 3 22.3 12.2 37.8 39.6 No ----
35.4 3 16.0 20.0 37.8 39.6 No ----
22.3 15.7 37.8 39.6 Install 42-inch ozone
38 Yes influent
18-0 20.0 37.8 39.5 piping
22.3 22.7 37.8 39.6 Additional ozone
45.0 Yes contactors 4
15.0 30.0 37.8 39.4
Existing ozonated channel set-point is WSE 37.8 feet.
2 Represents level measured downstream of sedimentation basin finger weirs. WSE set at 39.8 feet.
3 Flow above these values require a change infrastructure modification.
'Assumed ozone influent piping modifications to existing, similar to 38-mgd expansion.
Hazen and Sawyer I Hydraulic Profile Evaluation 7-4

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
The hydraulic model did not identify hydraulic issues at 32 mgd. At 38 mgd, the headloss through the
existing 24-inch ozone influent piping will be excessive and will result in submergence of the sedimentation
basin weirs. The expanded facilities may treat up to 35.4 mgd prior to submerging the sedimentation basin
weirs. This weir cannot be raised and may result in an increased water surface elevation in the rapid mix
that will impart an uplift force on the deck and result in unacceptable freeboard (e.g., less than one foot).
To prevent submerging the sedimentation basin weirs in the 38 mgd expansion phase without the use of
intermediate pumping ozone influent piping would need to be up-sized from the existing 24-inch diameter
to a 42-inch diameter pipe.
Figures 7-3 and 7-4 illustrate the hydraulic profile for 38 mgd with the larger 42-inch ozone influent piping.
The existing pipe supports are sufficient to handle the loads associated with the larger 42-inch piping. It is
recommended that the existing pipe supports be replaced to accommodate potential spacing constraints
with the existing support configuration and for ease of installation. Increasing the influent piping to 42-inch
diameter will require consideration of construction sequencing to minimize impacts to plant operation. The
ozone influent piping could be upgraded such as that only one contactor is offline at a time.
As an alternative to upsizing the ozone influent piping, an additional ozone contactor could be constructed
to prevent the hydraulic limitations described at flows greater than 35 mgd. As described in Section 11,
adding a fifth contactor will also increase hydraulic detention time and is recommended for a plant capacity
of 45 mgd.
The construction cost opinion associated with addressing the hydraulic challenges for plant expansions are
incorporated in Section 19. These include installing sedimentation basin finger weirs (existing
sedimentation basin cost), and increasing the ozone influent pipe size (ozone cost for 38 mgd only).
Hazen and Sawyer I Hydraulic Profile Evaluation 7-3

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Staff have indicated that at flows above approximately 18 mgd, the baffles in the raw water ozone contactor
are submerged; the hydraulic model confirms this. Adjusting the control scheme of the ozone influent
valves to increase percent open reduces headloss and prevents submergence of the existing
sedimentation basin weir. However, the recommended modified finger weir elevation mitigates future
hydraulic impacts from the expansion.
7.2 Future Facility Hydraulic Capacity
The WTP expansion will influence plant hydraulics through the existing treatment train. Unit processes
upstream of ozone will be impacted by the future plant expansion even though these existing processes
are not anticipated to treat additional flow. This hydraulic impact is due to increased flow through the
existing ozone contactors and common channels to include the ozonated water channel and the filtered
water channel. The hydraulic model for the proposed expansion uses the following assumptions:
• The existing piping from the impoundment to the raw water contactor has been
increased to 48-inch, except for the length of pipe penetrating the pre-sedimentation
basin impoundment berm.
• All six existing sedimentation basins are in operation.
• The sedimentation basin finger weirs are set at a WSE of 39.8 feet.
• One SuperPulsatore basin is in operation at 32 mgd, two SuperPulsator® basins are in
operation at 38 mgd, and three SuperPulsator®basins are in operation at 45 mgd.
• Four ozone contactors are in operation through 38 mgd. At 45 mgd two additional
ozone contactors are assumed.
• The ozonated settled water channel set-point at a WSE of 37.8 feet is maintained to
prevent upstream hydraulic issues.
• Four new filters are in operation at 32 mgd, six new filters are in operation at 38 mgd,
and eight new filters are in operation at 45 mgd.
The hydraulic model for the expanded WTP assessed the following operational scenarios at 32, 38, and
45 mgd capacities:
• Flow split for the existing rated plant capacity of 22.3 mgd through the existing
sedimentation basin trains.
• Flow split maximizing the capacity of the new SuperPulsator®trains.
The hydraulic modeling identified critical plant hydraulic control points and the corresponding flow
thresholds. If a flow threshold is exceeded, then a change is required at the critical control point. Table 7-1
identifies key water surface elevations in the ozonated water effluent channel and in the sedimentation
basin effluent immediately downstream of the effluent weirs for each scenario. Table 7-1 also documents
the required modifications to accommodate the individual flow scenarios. Figures 7-3 and 7-4 detail the
hydraulic profiles for the two plant expansion scenarios.
Hazen and Sawyer I Hydraulic Profile Evaluation 7-2

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
7. Hydraulic Profile Evaluation
7.1 Existing Facility Hydraulic Capacity
Raw water from the Tar River feeds into the raw water pump station which can convey raw water to a 63
million gallon pre- sedimentation impoundment or to the WTP. After the pre-sedimentation impoundment,
the water is conveyed through a raw water ozone contactor followed by two rapid mix chambers typically
operated in parallel. Coagulated water flows through nine flocculation basins in series. Flocculated water
feeds into two sedimentation basin influent channels that distribute flow to the six sedimentation basins. At
the end of the basins, settled water flows over a submerged weir wall.
Settled water collects in a common channel and then feeds into the ozone facility where flow splits to four
baffled ozone contactors. At current flows, only two contactors are typically operated. Settled water is
conveyed through a 24-inch pipe dedicated to each ozone contactor equipped with a flow meter and a
modulating butterfly valve. Ozonated water collects in a common ozonated water channel. The water level
in the channel serves as a hydraulic control point for the facility with a target level set-point at a water
surface elevation (WSE) of 37.8 feet.
Ozonated water flows through a common channel to seven filters. The water flows by gravity through the
filter media, underdrain, and the individual filter effluent lines equipped with a flow meter and butterfly flow
control valve prior to feeding into a common filtered water pipe and channel configuration. The filtered
water passes over a weir into a clearwell pump station influent channel that directs filtered water into the
wetwell. Clearwell pumps lift water to two 3 MG ground storage tanks operated in parallel. A pipeline feeds
finished water from the ground storage tanks to the finished water pump station for conveyance to GUC's
distribution system.
A hydraulic profile from the rapid mix process through the ozonated water channel was developed by
Hazen in 2014. This profile determined the elevation for the new finger-type weirs for the sedimentation
basin effluent(at WSE 39.5 feet) to mitigate distribution and water quality challenges observed in the
basins. The hydraulic profile also identified and addressed other hydraulic bottlenecks in the water
treatment process. The Technical Memorandum. Final Technical Memorandum— WTP Sedimentation
Basin Evaluation, documented other hydraulic improvements to include opening the ozone influent butterfly
valves more fully and operating three ozone contactors at flows higher than 18-9 mgd. Further evaluation in
this PER effort demonstrated that a modified finger weir elevation (WSE 39.8 feet) will minimize the impact
of future flow through the ozone facility while maintaining an acceptable 1-foot freeboard in the existing
upstream process basins. Figures 7-1 and 7-2 illustrate the updated hydraulic profile at the rated plant
capacity of 22.3 mgd for the following two scenarios:
• Current Operation: The existing sedimentation basin effluent weir at WSE 39.25 feet
and ozone influent valves open less than 60 percent.
• Recommended Operation: New sedimentation basin finger-type weirs at WSE
39.8 feet and ozone influent valves open less than 80 percent.
Hazen and Sawyer I Hydraulic Profile Evaluation 7-1

i
Ground StonesT .+ Legend
Filters and New Clearwell E
_- Filter Gallery Pump Station Future IN —
'*' SuperPrd for V t E_ 1}
// -"" Future
I �JL
y
a , -
- a Ir
mom IF Future
Vertical \II/ II High Service •e
Rapid Mix .. in
I ,` 0 1Pump Station
II
.__ ,I I 0OzoneCOntaotOf II
_ J
I 1 tl i \ an�
I i e
81 •� l
I 1 Rapid Mix/ r P _-_— _� .-. ���Qe�s---
1 _ 1.. Flocculation/ y 1 I
i 11. Sedimentation \
r a. 1111I _ .
Chemioal Storage &I a
O \`
Building ..' ---- --
4.
Future OAC Contactor
d `
iq I
1 qq& i
\ A q
y E Y 0 O.•
I
--------I:
\ Residuals
In) f Access Road
11
V
Berm
of Bet
Stormwater and
I Residuals Pipeline
/
PHASE 1 WTP IMPROVEMENTS
GREENVILLE UTILITIES COMMISSION
PARTIAL YARD PIPING PLAN FIGURE 6-10
Hazen `•60-°- SITE LAYOUT OF PROPOSED
FACILITY EXPANSION

�� - 32gd 1
' I 38 mgd i
_.._-- i , •/ :_ __1 - Future
\�_��i�
-ini
•
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'di —------ '''''.°-'—'.-/:----i I
I
is
__
i
r.
rti
i PHASE 1 WTP IMPROVEMENTS
PARTIAL YARD PIPING PLAN GREENVILLE UTILITIES COMMISSION
oa-o•
FIGURE 6-9
57 Hazen SITE LAYOUT OF PROPOSED
FACILITY EXPANSION

/MIMEORDwo\I t40
i i S .' If' ;STORK#THE ,
... EERFUTURE 10011
M NUM
i , RAlgMll
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•
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•
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'
L /' ` MOM MD ENTER GAVERT I — •. _ 1.
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' T-1--r I
1 PPE-SEDIMENTATION
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IMPOUNDMENT SODIUM rT1tEi
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ffi
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Q • OMNIE CONTACTOR.TVE
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99
PHASE 1 WTP IMPROVEMENTS
r YARD PIPING PLAN o GREENVILLE UTILITIES COMMISSION
0
FIGURE 6-8
Hazen SITE LAYOUT OF SEPARATE
,V TRAIN CONCEPT

|
Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
3MS
C|eonwoU
�
�
3M8
Cleonwe|
�
-
Main and Elect. |
' Building
' High Service
--| ! Operations
. . --- andC|oanwoU
' BuildingPump Stations
�
` | [][3[][][][]0 1
� | r----`------r--�—` m
0
� � w u'
o Sedimentation Basins -0
/ m u
| �X
L"^ �
� FooUhy
�
� Electrical
Building
| �
(
� r
)
� --
�
Figure 6'7: Site Layout of Existing Water Treatment Plant Facilities

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
There is an opportunity for a hybrid of the integrated train and separate train concepts. The initial
expansion of the plant to 32 or even 38 mgd could be implemented west of the existing WTP as presented
above. This would allow utilizing the entire available capacity of the existing facilities (such as ozone). Once
the full capacity of the existing processes is realized, additional expansion could occur by providing a
separate treatment train. This hybrid approach would allow for the full leveraging of the existing facilities
and provide for future expansion in an open portion of the WTP site while reducing the complications that
arise when increasing the flow to the existing facilities higher than 32 or 38 mgd.
Hazen and Sawyer I Water Treatment Plant Capacity Planning 6-8

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
an entirely new treatment train with separate flow control. So, the two treatment trains would operate
independently after the flow split. All of the expanded treatment capacity would be provided by the new
separate train.
This strategy could significantly reduce the number and duration of WTP shutdowns during construction. A
separate treatment train would also reduce potential risks to the existing facility operation during
construction. By locating the new facilities in a more open portion of the site with few constraints due to
existing infrastructure, the new structures would be more easily expanded in the future. Additionally, by
conveying new treatment capacity through an entirely new train and not increasing the flow to any of the
existing facilities, the hydraulic limitations of the existing piping and facilities could be minimized.
A separate train would allow for future expandability well into the future but utilizing open space on the site.
The separate train concept would also completely separate the construction area from the WTP
operations, simplifying maintenance of plant operations and reducing the risk of damage to the existing
facilities.
This concept would have some limitations. Redundancy would not be provided at the process level but
instead would be train dependent. Access would be more difficult with the separate train concept due to the
distance between the existing facilities and the proposed facilities. A separate train would also require
higher capital costs comparted to the integrated expansion concept.
6.3.3 Integrated Train Concept
With the integrated expansion concept, new facilities would be constructed to the west of the existing
ozone and filter facilities. This would allow for extension of the existing filter galleries to serve new filters.
New rapid mix and clarification would be located to the west of the Ozone Facility where space is allocated
for two additional ozone contactors.
Future bulk chemical storage will be located adjacent to the existing chemical storage. This location will
streamline delivery of chemicals. Future ground storage tanks will be located adjacent to the existing tanks.
Figures 6-9 and 6-10 provide a layout of the proposed facility expansion to address capacity needs in
2050. Additional facilities, such as UV disinfection and GAC have space allocated north of the existing
treatment plant and east of the ground storage tanks.
The advantages of this expansion concept are that the remaining capacity in the ozone facility is leveraged
and it takes advantage of the process reliability and redundancy with tie-ins at each process between new
and existing facilities. This concept also maximized operator access by keeping new facilities in close
proximity to existing facilities. However, the area for expansion is limited by the wetlands located west of
the existing berm and fence. Expanding to the west will also impact the existing access road to the raw
water pump station in later phases of expansion.
Hazen and Sawyer I Water Treatment Plant Capacity Planning 6-7

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
CLEARWELL PUMP STATION
■FIRM
FILTRATION
■TOTAL
OZONE
CLARIFICATION
FLOCCULATION
RAPID MIX
RAW WATER PUMP STATION
0 10 20 30 40 50 60 70
Capacity (MGD)
Figure 6-6: Firm and Total Capacity of Unit Processes for 45 mgd WTP Expansion
6.3 Water Treatment Plant Site Planning
6.3.1 Expansion Concepts
The existing water treatment plant is located in the center of the plant site. Figure 6-7 provides an
illustration of the existing site plan. The finished water clearwells are northwest of the WTP. The existing
pre-sedimentation impoundment and space allocated for a future pre-sedimentation impoundment are
located south of the WTP site. Bulk chemical storage is located directly east of the existing sedimentation
basins.
In considering expansion of the water treatment plant, several options were evaluated to incorporate new
facilities with existing facilities. One approach is to expand the existing facilities by constructing new
process components to the west of the existing facilities. This concept has more limited space available for
construction of new facilities and limits buildout capacity. Therefore, a completely separate treatment train
concept was also considered in which new facilities would be constructed in a different part of the site and
configured for ease of construction and future expansions.
6.3.2 Separate Train Concept
The separate treatment train concept was developed to reduce the impact of the construction of the
expansion on the existing treatment plant and operations. Figure 6-8 illustrates the site plan for the
separate treatment train concept. In this concept, raw water would be conveyed to the existing WTP and to
Hazen and Sawyer I Water Treatment Plant Capacity Planning 6-6

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
'
CLEARWELL PUMP STATION
FILTRATION ■FIRM
■TOTAL
OZONE
CLARFICATION
FLOCCULATION
RAPID MIX
RAW WATER PUMP STATION
0 10 20 30 40 50 60
Capacity(MGD)
Figure 6-4: Firm and Total Capacity of Unit Processes for 32 mgd WTP Expansion
CLEARWELL PUMP STATION
' ■FIRM
FILTRATION
■TOTAL
OZONE
CLARFICATION
FLOCCULATION
RAPID MIX
RAW WATER PUMP STATION
0 10 20 30 40 50 60 70
Capacity(MGD)
Figure 6-5: Firm and Total Capacity of Unit Processes for 38 mgd WTP Expansion
Hazen and Sawyer I Water Treatment Plant Capacity Planning 6-5

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
6.2 Process Capacity
The concept of total versus firm capacity applies to all processes in the treatment train. The existing
processes were evaluated based on process design guidelines and based on hydraulic limitations. Some
of the existing processes are limited by the available volume and process effectiveness. For example,
conventional sedimentation basins should be limited to an overflow rate of 0.5 gpm/SF. The existing
sedimentation basins each have an overflow rate of 0.48 gpm/SF when the existing total plant capacity of
22.3 mgd is split evenly between the six basins. Therefore, the total clarification capacity in the existing
WTP is 22.3 mgd and the firm capacity is 18-9 mgd with one basin out of service. Other processes may be
limited by hydraulic constraints. For example, the existing two-stage rapid mix basins can provide the
recommended mixing time of 30 seconds for flows up to 50 mgd. However, when flows exceed 24 mgd,
the increased headloss causes the water surface elevation to rise to the bottom of the mixer slab and
cause uplift forces on the concrete slab. Therefore, the rapid mix basins have a total capacity of 24 mgd.
When one basin is out of service and 24 mgd can only go through one rapid mix basin, more than
30 seconds of mixing is still provided; however, the hydraulic constraint limits the firm capacity to 24 mgd.
Figures 6-3, 6-4, 6-5 and 6-6 illustrate the total and firm capacity of each process for the existing WTP and
for each of the expansion phases (except high service pumping). The capacity increments for high service
pumping are excluded from Figures 6-3—6-6 since pump capacity is a function of distribution system
capacity, and the timing of system improvements will not correlate exactly with the WTP expansion phases
of 32, 38, and 45 mgd. As described in Section 5, high service pumping capacity increments will align with
distribution system timeframe recommendations for the years 2020, 2025, 2030, 2040, and 2050.
CLEARWELL PUMP STATION
■FIRM
FILTRATION
• ■TOTAL
OZONE
CLARIFICATION
FLOCCULATION
RAPID MIX
RAW WATER PUMP STATION
0 5 10 15 20 25 30 35
Capacity (MGD)
Figure 6-3: Firm and Total Capacity of Existing Water Treatment Plant Processes
Hazen and Sawyer I Water Treatment Plant Capacity Planning 6-4

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
55 - S-ProposedSuperPulsators,
GUC-only Average Day Projection(with conservation and efficiencies)-limited to Capacity=52.2 mgd
service area
50 • • GUC-only Observed Average Oat
•
- ^ GUC-only Peak Day Projection with PF-1.54(with conservation and efficiencies)-
1 ' limited to service area
8 Proposed Filters,Firm
GUC-only Observed Peak Day Capacity=45 mgd
45 :• r-� 2 ProposedSuperPulsators,-r •• — •• — -
GUC/Winterville 90.Percentile+Max Wholesale Projection+0.76 mgd industrial
(with conservation and efficiencies) Capacity=42.2 mgd
Addition of 0.76 mad Nonindustrial Demand •
40 - . 6 Proposed Fitters, ,-='
i Firm Capacity=38 1
1 Proposed SuperPulsator,
- Capacity=32.2 mgd;
35 t
4 Proposed Filters,Firm �,
- ap Cacity--•32 mqd -
c
Q 30 I
25 - Current Clarification _ - '
Capacity=22.3 mgd
.,r: •• ....., -
▪Existing Firm Filtration
20 Capacity=19.2 i•• p
• •
. •
15 4 • -
• •
5
2005 2010 2015 2020 2025 2030 2035 2040 2045 2050
Figure 6-2: Recommended Incremental Clarification and Filtration Capacity
Hazen and Sawyer I Water Treatment Plant Capacity Planning 6-3

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Firm Filtration
Capacity=32.0 MGD
Firm Raw Water Firm Plant Capacity
Supply=32.14 MGD_ '� I I I l
=31.15 MGD
Residuals= Backwash Supply
0.144 MGD =0.850 MGD
Figure 6-1: Example of Water Treatment Plant Capacity Schematic and Internal Recycles
Table 6-1: Firm and Sustained Capacity for Future Capacity Increments
Permitted Firm Filtration Backwash Water Total Sustained Capacity
WTP Capacity Rate 1 Use Delivered to System
(mgd) (mgd) (mgd) (mgd)
22.3 19.0 0.36 18.6
35.0 32.0 0.46 31.5
41.0 38.0 0.66 37.3
49.0 45.0 0.77 44.2
' With one filter out of service for backwash.
The SuperPulsator® high rate clarification technology was identified as the preferred clarification technology
due to a reduced footprint compared to conventional sedimentation basins. The initial SuperPulsator®
layouts consisted of basins in 5 mgd, 7 mgd, and 10 mgd capacity increments. The current treatment plant
clarification capacity is 22.3 mgd. To provide adequate treatment capacity through 2035, one 10 mgd
SuperPulsator®basin is sufficient. To reach the final treatment capacity in 2050, two additional 10 mgd
SuperPulsator®basins would be required. The 10-mgd basins were selected over the smaller basins to
minimize the number of basins required to fit within the available footprint for capacity expansion. Using the
smaller basin sizes, more than three basins will be required for the buildout treatment capacity. Also, larger
capacity basins were deemed more cost effective on a unit capacity basis. Figure 6-2 illustrates the
recommended incremental filtration and clarification capacity. An additional filter is recommended to
provide firm filtration capacity at the WTP. Figure 6-2 also illustrates the current filtration capacity as
19.2 mgd accounting for one filter out of service for backwashing, which is the basis for comparison of
future plant capacity going forward.
Hazen and Sawyer I Water Treatment Plant Capacity Planning 6-2

Preliminary Engineering Report
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6. Water Treatment Capacity Planning
6.1 Recommended Water Treatment Capacity Increments
Recommended treatment capacity increments take into consideration the incremental filtration and
clarification capacity that align with projected demand curves for the GUC water service area. A discussion
on the development of the water demand projections is provided in Section 3. Capacity increments should
allow for 15 to 20 years between periods of construction so plant operation is not continually being
interrupted by construction activities. The projections indicate that water demands could exceed the
existing WTP capacity of 22.3 mgd in the near future if warmer and drier weather that was observed in
2005, 2007 or 2010 are repeated. It is also important to note that when any one filter is out of service for
backwashing, plant capacity is reduced to an effective rate of 19.2 mgd. To account for planning,
engineering design, and construction, it is assumed that a capacity expansion would be online no sooner
than 2020, which reflects some treatment capacity vulnerability.
The long-term treatment capacity needs for GUC are approximately 45 mgd by 2050. If the expansions are
distributed over the planning period, then the initial capacity expansion should be to 32 mgd, which is
expected to meet demands to 2035. A capacity expansion to 38 mgd would be expected to meet the
service area needs until 2042 and a capacity of 45 mgd accommodates the approximate demand in 2050.
The proposed filters will have identical treatment capacity to the existing filters at a loading rate of 4 gallons
per minute per square foot(gpm/SF), or 3.2 mgd per filter. Unlike the existing filters, the proposed filters will
be arranged in an opposing filter layout and added in pairs to efficiently use the available space for
filtration. These considerations will result in a filter-driven treatment capacity increment of 6.4 mgd.
The DWR Public Water Supply Unit permits WTP capacity based on the filtration capacity. This convention
has been historically used in the water treatment industry. In this PER, planning is based on the firm
filtration capacity, which is defined the available filtration capacity with one filter out of service (e.g., filter
offline for backwash or maintenance). Firm filtration capacity is not equal to the maximum capacity at which
the WTP can pump water into the distribution system due to on-site water use for backwashing filters.
Using a conservative 48-hour filter run time, the estimated net water production for a 32 mgd rated facility
is approximately 31.5 mgd. The concept is illustrated for a WTP with a firm filtration capacity of 32 mgd in
Figure 6-1. Throughout this PER, references are made to 32, 38, and 45 mgd capacity based on firm
filtration capacity, although the permitted capacity will align with the total filtration capacities of 35, 41, and
49 mgd, respectively. It should be noted that the maximum sustained capacity delivered to the distribution
system will be less due to internal potable water uses for filter backwash. Table 6-1 summarizes firm and
sustained capacity for the existing WTP and future capacity increments.
Hazen and Sawyer I Water Treatment Plant Capacity Planning 6-1

Preliminary Engineering Report
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below the lab reporting value so an accurate CSMR for each cannot be calculated. If
sulfate levels are significantly lower than the reporting value, then the CSMR would be
above the recommended value. The higher alkalinity of the wells may mitigate the impacts
of a higher CSMR on lead corrosion.
• Fluoride: Fluoride levels at some of the wells are slightly higher than the U.S. Public Health
Service recommendation of 0.7 mg/L.
• Iron and Manganese: Average iron and manganese levels are lower than the EPA
secondary maximum contaminant levels. However, iron levels are higher in the Northside
Blending Station and Washington St. wells, and additional treatment would be needed to
provide similar aesthetic quality as the finished water from the WTP.
The water quality data does not suggest that there are significant challenges with blending groundwater
from the wells with the WTP finished water. However, corrosion inhibitor systems would be required at
each of the wells to provide a consistent water quality and corrosion control as compared to WTP finished
water.
When considering the necessary WTP capacity improvements and efficient incremental capacity
increases, the use of groundwater sources does not present itself as an effective approach long-term water
supply. The facilities are an important element for providing water supply flexibility in the event of a water
supply emergency. Groundwater supply that GUC has banked under the CCPCUA could be used
strategically to meet the needs of GUC's wholesale customers while balancing water system supply and
capacity in the GUC system.
Hazen and Sawyer I Water Distribution System Model Update 5-52

Preliminary Engineering Report
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The WTP and the wells have different water sources and treatment processes, so there are distinctive
differences in typical water quality parameters. Blending of the systems may cause marked changes in
water quality within the blending zones. Differences in water quality between water systems create the
potential for water quality fluctuations in blending zones. Therefore, average finished water quality
conditions in each system were evaluated to ascertain the potential for impacts in the blending zones,
especially related to key parameters impacting lead and copper corrosion. Moreover, a comprehensive
analysis of historical water quality data was completed to investigate potential water quality impacts of
distribution system blending.
The average total chlorine residual and orthophosphate (e.g., corrosion inhibitor) levels are noted in
Table 5-12 for the WTP. For well water to be utilized in the distribution system, chloramines and
orthophosphate will need to be added for disinfection and corrosion inhibition, respectively. This will require
satellite chemical storage and feed systems at each well to be blended with the WTP finished water.
Dosing will need to achieve levels similar to the WTP finished water for minimal disruption to chloramines
residual levels and corrosion inhibition needs.
The water supply wells have natural fluoride with level up to 1.2 mg/L. The US EPA has established a
primary MCL for fluoride at 4 mg/L. A secondary standard is set at 2.0 mg/L to reduce the potential for
tooth discoloration. The existing wells meet both US EPA's primary and secondary standards for fluoride.
The U.S. Public Health Service (PHS) also publishes Drinking Water Standards related to community water
fluoridation. In 2015. PHS revised its recommendation for the optimal fluoride concentration to 0.7 mg/L to
provide the best balance of protection from dental caries while limiting the risk of dental fluorosis. The
earlier PHS recommendation for fluoride concentrations ranged from 0.7-1.2 mg/L. The fluoride levels in
these wells is within the range recommended byPHS and similar to the average fluoride concentration of
9 9
1.0 mg/L in finished water produced by the WTP.
An analysis of the historical water quality data is summarized as follows:
• pH: Average pH levels between the WTP and wells is similar based on historical data.
Chemical addition at the well sites may impact the pH levels going to the distribution
system.
• Alkalinity/dissolved inorganic carbon: The average alkalinity is significantly higher at three
of the well sites compared to the WTP.
• Hardness: Most wells have higher hardness levels as compared to the WTP. The Evans
Park well has very low hardness.
• Conductivity: Conductivity can influence galvanic corrosion of lead in the distribution
system. Levels at all four wells are significantly higher the WTP finished water. Total
dissolved solids were estimated based on the conductivity data and the levels are below
the secondary standard of 500 mg/L.
• Chloride-to-sulfate mass ratio: Research indicates that chloride-to-sulfate mass ratio
(CSMR) values greater than 0.5 may present a concern for lead corrosion. The average
CSMR for the GUC WTP is at an acceptable value. Sulfate levels at three of the wells were
Hazen and Sawyer I Water Distribution System Model Update 5-51

Preliminary Engineering Report
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Table 5-12: Blending Analysis Data Comparison
Washington Northside
Street Deep Southside Evans Park Blending
Parameter GUC WTP I Well 2 Deep Well 2 Deep Well 2 Station 2
Total chlorine 3.9 N/A N/A N/A N/A
residual (mg/L)
pH 7.7 7.9 7.9 8.0 7.8
Alkalinity(mg/L as 27 241 249 255 65
CaCO3)
Dissolved inorganic 6.8 59 62 62 16
carbon (mg/L as C) 3
Hardness(mg/L as 30 33 60 11 21
CaCO3)
Orthophosphate 1.2 0 0 0 0
(mg/L as PO4)
Total organic carbon 2.9 N/A N/A N/A N/A
(mg/L)
Turbidity(NTU) 0.044 0.21 0.15 0.28 0.28
Conductivity 88 484 507 514 276
(umhos/cm)
Chloride(mg/L) 15 5.5 6.3 8.3 20
Sulfate(mg/L) 36 < 15 < 15 < 15 39
Chloride-to-sulfate 0.42 N/A N/A N/A 0.50
mass ratio
Fluoride (mg/L) 1.0 0.87 0.50 1.1 1.2
Iron (mg/L) 0.0088 0.23 0.14 < 0.06 0.14
Manganese(mg/L) 0.0064 < 0.010 0.021 < 0.010 < 0.010
'January 2014 through September 2016;conductivity, chloride, and sulfate are typical values from lab daily analysis
log sheets.
2 January 2014 to September 2016 data.
3 Estimated based on alkalinity and pH from OCCT Evaluation Technical Recommendations for Primary Agencies and
Public Water Supply.
Water quality data was to assess potential impacts from blending of groundwater with finished water from
the WTP and to identify factors that could impact lead and copper corrosion.Water quality data evaluated
for this analysis includes finished water quality from WTP monthly operating reports (MORs)and water
quality from well sampling events.
Hazen and Sawyer I Water Distribution System Model Update 5-50

Preliminary Engineering Report
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Greenville Utilities Commission
5.9 Evaluation of Groundwater Sources
5.9.1 Available Groundwater Supply
The existing capacity of GUC's groundwater wells is approximately 0.88 mgd based on a 12-hour safe
yield. The groundwater wells are subject to a 75 percent reduction by 2018 per the CCPCUA rule;
however, GUC has banked groundwater that could be used to extend the opportunities for groundwater
supply into the future. Currently, the wells are primarily used for backup water supply. The water supply
needs for the GUC service area are approximately 30 mgd over the next 15 years and 46 mgd by 2050.
Therefore, the existing wells would provide only a marginal amount of the long-term water supply needs for
GUC. Banked water could be a short-term option to offset additional withdrawals but CCPCUA rules would
limit a significant expansion in the use of groundwater resources to meet long-term water supply needs.
The use of groundwater wells was also considered in strategic locations to increase water supply locally
and potentially offset some of the new transmission capacity needed for portions of the distribution system.
The majority of the future growth and development in the service area is expected in the southern portion
of the system, particularly southeast and southwest. New water supply wells are not expected to provide
sufficient capacity to meet the demands in these areas and offset proposed transmission improvements.
However, groundwater sources may be useful for supplying outlying areas, such as the northern part of the
system. Installation of wells in the northern portion of the service area would reduce the need for pipe
capacity expansion in this area. However, then this area would be dependent on the reliability of the wells.
Another option could be for GUC to transfer some of its banked water to one or more wholesale customers
to offset their needs for potable water. While manageable, the variable supply to Farmville does impact
system performance. If a scenario were considered where Farmville was allowed to increase its reliance on
groundwater withdrawal via banked water, the demand variability on GUC's system could be reduced.
Banked water could be used strategically to ensure that water supply needs for GUC and its customers are
met while balancing water system capacity.
ASR was previously investigated as a source of water supply to facilitate meeting maximum day demands.
ASR is not implemented at this time and is not assumed to be a long-term source impacting water supply
needs.
5.9.2 Water Quality Evaluation
Water quality data from the four water supply wells were analyzed to investigate potential impacts on
distribution system water quality. This analysis excluded the Eastside and North Greene St. wells since
they have fluoride levels exceeding the secondary MCL so would require additional treatment to meet
primary drinking water standards. Water quality was compared to finished water produced by the WTP to
assess potential issues with blending. Data from January 2014 to September 2016 was assessed for the
WTP, Washington Street Deep Well, Southside Deep Well, Evans Park Deep Well, and Northside Blending
Station and is summarized in Table 5-12.
Hazen and Sawyer I Water Distribution System Model Update 5-49

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
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—+-2020 Current Pipes t2050 Improved Pipes ' 2040 Improved Pipes
300 — ,
250
♦ * ' '•i., • •♦ •% • • ?•••.
% '•t•
•
100 '
- Single Pump Two Pump Firm Pumping
50 — - Combination Combination
Combination
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70
Flow, mgd
Figure 5-30: System Curve Development for Capacity Variability with 2050 Pumping Combinations
Hazen and Sawyer I Water Distribution System Model Update 5-48

Preliminary Engineering Report
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-2020 Current Pipes -2050 Improved Pipes -' *•_ 2040 Improved Pipes
FWP 1,2(n),4 FWP 1,3(u),4
300 —
MAX+Wholesale 2050 Firm Pumping
250 i '• _•••• r Capacity
MAX '••
•••90%+Wholesale •.
200 • ..i r?
- ADD
MIN i
•
150
- 2040 Firm Pumping
100 — . Capacity
•
50 —
0 5 10 15 20 25 30 35 40 45 50 55 60
Flow, mgd
Figure 5-29: System Curve Development for 2040 and 2050 Upgraded Firm Pumping Capacities
Hazen and Sawyer I Water Distribution System Model Update 5-47

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
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— --2020 Current Pipes 2020 Improved Pipes 2025 Improved Pipes
-2030 Improved Pipes t2040 Improved Pipes
300 — r ,
250 %-
. ♦ • : ♦ % •• • • • •/'
�• 4 •••
1
0 150 — - — -♦•; .-�!: • •.,
F- 1 ``, ••• 0` ••.•• •
1,
1 i `` .. ;` • `
1 11 A .••'
- Single Pump Two Pump Firm Pumping
50 — Combination
Combination Combination
0 5 10 15 20 25 30 35 40 45 50 55
Flow, mgd
Figure 5-28: System Curve Development with Variability through Upgraded Pumping Combinations
Hazen and Sawyer I Water Distribution System Model Update 5-46

Preliminary Engineering Report
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-2020 Current Pipes 2025 Improved Pipes -4P-2030 Improved Pipes
- -2040 Improved Pipes ---FWP 1,2,3 FWP 1,2,3(u)
MAX +Wholesale
-
250 - • • '•.-s
` ..... ••MA♦X ` '0
- 904/0 +Wholesale ♦' ••.
200 1 ♦♦••. 1
IIADD •
_ MIN
♦•.
100 - L • ,
50 - r r ,
0 5 10 15 20 25 30 35 40 45 50 55
Flow, mgd
Figure 5-27: System Curve Development for Existing versus Upgraded Firm Pumping through 2040
Hazen and Sawyer I Water Distribution System Model Update 5-45

Preliminary Engineering Report
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f2020 Current Pipes 2025 Improved Pipes -2030 Improved Pipes
--e-2040 Improved Pipes ---FWP 1,2,3
300 — , r
- MAX +Wholesale
250 — , r "+„• ,
••• ; MAX r �0
)11
•
90%+Wholesale •
200 — N• '
ADD
MIN
= 150
1— ♦
♦
. ♦
•
0 5 10 15 20 25 30 35 40 45 50 55
Flow, mgd
Figure 5-26: System Curve Development for Existing Firm Pumping Capacity through 2040
Hazen and Sawyer I Water Distribution System Model Update 5-44

Preliminary Engineering Report
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- --2020 Current Pipes -0-2020 With Improvements --0-2025 With Improvements
-0-2030 With Improvements -1--2040 With Improvements -0-2050 With Improvements
260
- MAX+Wholesale---0
240 - r ,- / ,
.
MAX / ,
220 -
90% +Wholesale
le
200 - * j
a) /
_ .
ADD
0 180
- MIN
140 - , -
0 5 10 15 20 25 30 35 40 45 50 55
Flow, mgd
Figure 5-25: System Curve Development with Recommended Distribution System Improvements
Hazen and Sawyer I Water Distribution System Model Update 5-43

Preliminary Engineering Report
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2050 system demand curve (refer to Figure 5-28). The assortment of pumping combinations illustrates the
range of flows available using constant speed drives. A gap in the range of deliverable pumping capacity
may be observed between the minimum and average day demand conditions. If dynamic pumping
capacities are desired in 2050 to more closely target anticipated demands within this gap, constructing a
new high service pump station could provide additional pumping combinations and flexibility. Alternatively,
one of the finished water pumps could be equipped with a variable frequency drive to provide this flexibility.
A similar situation presents itself in 2040 with the aforementioned identified finished water pump No. 2
replacement. The addition of a variable frequency drive to a single pump would again enhance pumping
flexibility to more closely match demands.
The proposed high service pumping improvements assume that the recommended distribution system
improvements have been implemented. Table 5-11 summarizes the recommended high service pumping
upgrades to ensure firm pumping capacity will meet the maximum day demand. If the distribution system
improvements are not completed as anticipated, additional pumping capacity will be required in earlier time
frames and the result will be significantly higher pressures in portions of the distribution system. Typical
pressures in the northern portions of the system near the WTP are on the order of 100 psi, with the model
predicting maximum pressures of about 110 psi. Without transmission improvements recommended for
2020 conditions, discharge pressure would exceed 125 psi and approach 135 psi.
Table 5-11: Proposed High Service Pumping Configuration for Future Capacity Scenarios
WTP Distribution System Max Day Firm Pumping
Capacity Piping Improvements TDH Demand Capacity Pump Capacity
(mgd) Completed (feet) (mgd) (mgd) Upgrade
2020 No 230 24.2 25.3 FWP 3(u)
2020 Yes 202 24.2 30.6 FWP 3(u) '
2025 Yes 202 26.6 30.6 None
2030 Yes 190 29.1 32.5 None
2040 Yes 186 36.6 42.4 FWP 2(n) 2
2050 Yes 198 47.2 48.4 FWP 3(n) 2
'Impeller upgrade and potential motor upgrade to 500 HP.
2 Replace existing pump with new 18.4 mgd pump.
Hazen and Sawyer I Water Distribution System Model Update 5-42

Preliminary Engineering Report
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Table 5-10: System Curve Development with Varying Demand Scenarios
Scenario Demand Description
1 MIN Minimum (33% of MDD)
2 ADD Average Day Demand
3 90% + Wholesale 90% of Max Day Demand + Maximum Wholesale
4 MAX Maximum Day Demand (MDD)
5 MAX+Wholesale Max Day Demand + Maximum Wholesale
An extensive combination of pump curves were evaluated considering the available capacity of existing,
upgraded, and new high service pumps. Pumps with an impeller retrofit or motor change out are noted with
a"(u)" for upgrade and pump replacements are noted with "(n)" for new pump. The performance curves
were used to determine an optimal combination of pumps that could meet an array of demand conditions
over time. A typical pump efficiency of greater than 70 percent was a requisite to ensure operating costs
were minimized
The parallel pump operating curve reflecting the existing firm capacity of the pump station was overlaid
amongst an outlook of future distribution system curves per Figure 5-24. If distribution system piping
improvements are not installed, the existing firm pumping capacity will not be able to achieve a maximum
day demand in the year 2020. The existing pumping infrastructure will be able to meet a maximum day
demand through 2030 with the implementation of distribution system improvements. If the impeller on
finished water pump No. 3 is retrofitted to provide additional capacity at greater discharge heads, the
maximum day demands will be met nearly through 2040 (refer to Figure 5-25). The maximum day demand
plus maximum wholesale would also be achieved through approximately 2030. The impeller retrofit also
allows the high service pumping capacity to be increased from approximately 23 mgd (the current high
service pumping capacity)to greater than 25 mgd without any transmission improvements. The impeller
retrofit for finished water pump No. 3 may also require a motor upgrade from 450 horsepower(HP) to
500 HP.
GUC staff prefers to retain the ability to meet shifting daily demands without the introduction of variable
speed drives to the pump station. The variability of pumped flows that can be achieved through 2040
(assuming an impeller upgrade to finished water pump No. 3) is illustrated in Figure 5-26. The wide range
of available pumping combinations allows GUC staff to meet future demands without installing variable
speed drives.
The 2040 demands require the replacement of finished water pump No. 2 with a new 18.4 mgd vertical
turbine pump. The resulting firm parallel pump curve will meet maximum day demand plus maximum
wholesale in 2040. In 2050, finished water pump No. 3 should be replaced by an 18.4 mgd vertical turbine
pump. The system and pump curves reflecting the upgrades addressing future plant demands in 2040 and
2050 are illustrated in Figure 5-27. Parallel pump operating curves were developed and compared to the
Hazen and Sawyer I Water Distribution System Model Update 5-41

Preliminary Engineering Report
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through the existing 36-inch yard piping and suction manifold will range from 7 feet per second (ft/s) at
32 mgd WTP capacity to 9.9 ft/s at a 45 mgd WTP capacity. Velocities greater than this range warrant
transmission main upgrades to reduce the potential for cavitation and/or erosion issues, reduce the motor
size required for future upgrades to the high service pumps, and to maintain a reasonable minimum
clearwell level. Piping upgrades would dramatically affect both high service and backwash pumping
operations requiring multiple shutdowns and isolation events. To mitigate these disruptive activities other
than altering the existing high service pump station, constructing a new high service pump station is
proposed in the future (post 2050). The layout of the pump station is located to the east of the ground
storage tanks as shown in Figure 6-10. Piping upstream of the pump station will connect to the ground
storage piping network and flow to the distribution system downstream of the pumps.
Table 5-9: Hydraulic Institute Standards Criteria for Can-Style Vertical Turbine Pumps
Non-compliant Finished
Hydraulic Institute Protocol Requirement 1,2 Water Pump No. 3
Approach length 5 pipe diameters (minimum) 1, 2, 3, and 4
Approach velocity 4 ft/s (maximum) ---
Suction centerline to bell 2.0 x can inner diameter 2, 3, and 4
Suction bell to can invert Suction bell diameter/2 1 and 2
Velocity between can and flange 1 5 ft/s (maximum) --
'Can inner diameter.
2 Suction bell diameter.
3 Assumes can inner diameter for finished water pump No. 2 is 48 inches(based on Record Drawings).
5.8.1.2 High Service Pumping Hydraulic Evaluation
Using the distribution system hydraulic model, system curves were developed to evaluate hydraulic
conditions for high service pumping at future demand scenarios. The system curves developed included
the recommended distribution system improvements for 2020, 2025, 2030, 2040, and 2050. Individual and
parallel pump operating curves were then developed to compare pump station performance for these
system curves. Subsequently, high service pumping improvements were developed to meet the demands
in future years.
Six system curves were developed, each based on a range of five different demand scenarios. Table 5-10
summarizes the development of the system curve with different demand scenarios. The design goal was to
meet demand scenarios 1 through 4 at a minimum and achieve scenario 5 (MAX + Wholesale) for added
flexibility. One system curve analyzed the year 2020 without distribution system piping improvements. Five
other system curves represented the years 2020, 2025, 2030, 2040, and 2050 with recommended
distribution system improvements. Figure 5-23 illustrates the six system curves with their respective
demand scenarios. The 2020/2025 and 2040/2050 curves overlap one another as a result of the
construction timeframe proposed for the recommended distribution system improvements.
Hazen and Sawyer I Water Distribution System Model Update 5-40

Preliminary Engineering Report
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5.8 High Service Pumping Improvements
5.8.1 Use of Variable Speed Drives
The finished water pump station at the WTP houses four constant speed, vertical turbine pumps. The can-
style pumps transfer finished water from two 3 MG ground storage tanks to the distribution system.
Finished water is drawn from the ground storage tanks and conveyed to the pump station through a
36-inch pipeline to the four high service pumps and single filter backwash pump. The existing high service
pump design conditions are summarized in Table 5-8.
Table 5-8: Summary of Design Parameters for Existing High Service Pumps
Motor
Year Installed or Design Flow Horsepower Efficiency at
Pump Last Upgraded Rate Design Head (HP) Design Point
Finished water 2000 14.4 mgd 200 feet 700 89.6%
pump No. 1
Finished water 2011 6.2 mgd 190 feet 250 82.9%
pump No. 2
Finished water 1990 9.4 mgd 190 feet 450 84.0%
pump No. 3
Finished water 1990 14.4 mgd 190 feet 700 86.0%
pump No. 4
5.8.1.1 High Service Pump Station Facility and Onsite Piping
The Hydraulic Institute Standards recommends an approach velocity below 4.0 ft/s for closed bottom
can-style vertical turbine pumps. Upon the installation of a new pump(greater than 18 mgd) in 2040,
approach velocities in the 36-inch suction inlet will surpass the recommended maximum. Flow
straightening devices may be installed in the suction piping and a turning vane at the can connection to
mitigate the potential for vortex formation and cavitation at the pump. A flow-conditioning basket connected
to the suction bell of the pumps may also be implemented to mitigate poor suction hydraulic conditions.
Other dimensional recommendations related to can sizing and spacing do not comply with Hydraulic
Institute Standards, some of which are summarized in Table 5-9. The existing well pits are adequate in size
to accommodate larger diameter(up to 60-inch) and taller pump cans (10 feet of spacing between the
suction pipe centerline and can invert). Modifications such as these are recommended for any proposed
upgrades to the existing pumping configuration address non-conformance with Hydraulic Institute
standards and subsequently improve pump performance and life. A physical model study should be
conducted to vet the appropriate corrective devices for implementation at the pump station.
Routing additional capacity to the high service pump station beyond the demands projected for 2050 will
require invasive construction or the addition of new pumping facilities to eliminate high suction piping
velocities in the existing facilities. As flows from the clearwells increase with WTP demand, velocities
Hazen and Sawyer I Water Distribution System Model Update 5-39

Preliminary Engineering Report
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IGreenville
Utilities WASHVNGSON Legend
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Automatic Flushing
Hazen and Sawyer I Water Distribution System Model Update 5-38

Preliminary Engineering Report
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Greenville HINGTpN
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Figure 5-23: 2040 Average Day Demand (Low-Demand Year)Water Age without
Automatic Flushing
Hazen and Sawyer Water Distribution System Model Update 5-37
Y Y p

Preliminary Engineering Report
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PyGrce'""lle Legend
Utilities NASHINGTON
N I (3 Existing Tank
eProp 2020 Tank
eProp 2040 Tank
Treatment Plant
Water Age
<=2 days
2-3days
CC ,ii -.
3-4 days
4-5 days
5-7 days
aG��
>7 days
litcP
N\G
i
1,
liy0� ' e�`Q ,SjPSON
yr
I . `�2 O
A
� �� Water Plant �_ ��TO<</s
..
A''• °Ili
111114,.‘
„iRsr
US 264 4_. vrL c " ..0 IFTH
' tZ'‘e,4-rvial 3 rvidirc 7..0V/7-6,
4it
` a
-.fr Eastaide Tank•
0 SouthaideTank
401 i Southeast Tank
3 ,st " .i,�" • . "
t n
(sr
ow
z
0 1 2 MAIN m
Miles
Figure 5-22: 2030 Average Day Demand (Low-Demand Year)Water Age without Automatic
Flushing
Hazen and Sawyer I Water Distribution System Model Update 5-36

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
IV Greenville tNGTON
AUtilities WASH Legend
N e Existing Tank
/ Q Prop.2020 Tank
® Prop.2040 Tank
y� �1l1 Treatment Plant
Water Age
-<=2 days
2-3 days
CC
3-4 days
\ ***1. i '
4-5days
5-7 days
->7days
,�1
�G
�G
SIll 1....,,\„
�s
20� v� e��Lp "sIPtON
r,Q
v
1 III
'w! *all
cQ' Water Plant R1.0.6. s
lir,
.,..,„
a. -• T
US 264 4-- �e.Ii- Off, ` . „FIFTH
``• �G0'' NTy
iti
Itior t‘C'55
--, illi;'I`r ••EastndeTank•
•t "t
' WO •Ta Southsidenk ;ice
..,i ari Southeast Tank
4/2
z
0
• o0
Z
0 1 2 MAIN m
Miles
Figure 5-21: 2025 Average Day Demand (Low-Demand Year)Water Age without
Automatic Flushing
Hazen and Sawyer I Water Distribution System Model Update 5-35

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
I Greerwiile NINGTON
Utilities WAs Legend
N -T- Existing Tank
1
1` / Li Prop.2020 Tank
OProp.2040 Tank
20li0 Treatment Plant
—
Water Age
"' --<=2 days
2-3 days
Cr
FT ` —3-4 days
L.N............
\\ ,... ce
R 4-5 days
N -�' 5-7 days
°' t, >7 days
NX°1:121kolt ,
kkG
tic ' I
,
i b
2 v ,i \ scPPGN
ii -„t ir- 4,4111
\ &- PACT
0 _ . Oa NUS
4.4 .
Ilir
US 264 !-rf-'tirr/! sdt4.' FFIFTA l
' �` o�G11
�'e t. �• p may • 4)Y
It k....," . cv% 4' 4'),?' •
{ ` Eastside Tank,
� sideTank WI Y
Southeast Tank
5.\3 ri
� ' Z s -� w
Z MAIN m
0 1 2
Miles
Figure 5-20: 2020 Average Day Demand (Low-Demand Year)Water Age without
Automatic Flushing
Hazen and Sawyer I Water Distribution System Model Update 5-34

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
10 Greenville SH`NG?Ott
70 Ut►lities wA Legend
N INI Treatment Plant
HF
. Existing Tank
eProp.2020 Tank
C 1 III Prop.2040 Tank
Pipe
Peak Hour Pressure
rc • <20 psi
: EE
. i
• >80 psi
N G1
aG
20IT
� e�<L ST d.. 1o.
a, Agisill
W p' %IF'
ct Water Plant '-q. Otti pr
lir, *ler°
6 t Cs` FIRST
US 264 a- '.\� O FIFTHAIh.
O o\G� 5 41TH
Fr V
w N e dG35
tir '
„y k�.-4r� = a Eastside Tank
eWestslde Tank Southside Tank
ZSoutheast Tank
vs 13 n
0
G
z
n
= w
Z MAIN m
0 1 2
Miles
Figure 5-19: System Pressure with 2050 Peak Hour Demand, Steady State, Pumps Set to
Maximum Day Demand, and Tanks 50% Full
Hazen and Sawyer I Water Distribution System Model Update 5-33

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
VGreenviUe
�i/�.� WpSHINGTGN Legend
N - i ® Treatment Plant
Existing Tank
oProp.2020 Tank
A .f)
a Prop.2040 Tank
i Pipe
Peak Hour Pressure
\ CC
4
• <20 psi
k •
20-35 psi
35-40 psi
40-80 psi
• >80 psi
N‘C' "Ilk
aG
ti0�� +
by � ` .._ _� tot+
ALI
J ' © �
' P
0, Water Plant c %If .
Qr ActoLUs t
A>OT ,FIRST "MOP
ti
US 264 0t4 FIFTH
N e NG�3
jessit,
1 10 riot i Eastsldc Tank N
0 J
Q
tt
Westside Tank � Southside Tank
0
Z Southeast Tank
us 13 n
0
c
- n
0 1 2
Z MAIN m
Miles
Figure 5-18: System Pressure with 2040 Peak Hour Demand, Steady State, Pumps Set
to Maximum Day Demand, and Tanks 50% Full
Hazen and Sawyer I Water Distribution System Model Update 5-32

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
IIGreenvil a SHING--ot Legend
utilities wA g
N EE0E
+ e
Q
n e Prop.2040 Tank
'
-, Pipe
• Peak Hour Pressure
<20psi
20-35 psi
4 . 35-40psi
40-80 psi
k: 116 0 -'1.15'c3Q''
• >80psi
NXG�
ti
P -
o
� 1i �o P.
2 ,.
#• N
C� ..t Water Plant c gCTO-OS
' US 264
4iArti .FmRST
US264 ..___-" �f t S0N4 FIFTH
\00' z ..1, TF�,TN
_ N e ao
Eastside Tank
"‹.) it'' e
gSouthside Tank e Z Southeast Tank
us 13 n
0
C
z
-< C
2 w
0 1 2
Z MAIN m
Miles
Figure 5-17: System Pressure with 2030 Peak Hour Demand, Steady State, Pumps Set
to Maximum Day Demand, and Tanks 50% Full
Hazen and Sawyer I Water Distribution System Model Update 5-31

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
I Greenville
►ISi Urllieles W ASHING1.ON Legend
N [Nifl Treatment Plant
0 Existing Tank
OProp 2020 Tank r---)---------)
n O Prop.2040 Tank
?+ Pipe
Peak Hour Pressure
• <20 psi
4 20-35psi
35-40 psi
N‘G 440-80 psi
• >80 psi
cP
C\G
lilt
20 a -.►
7"' c‘r I �u mac- '' • PT o Alliti4
ip"
ear "o � u� �-
Water Plant c�',"IC?-
Water r
F11M1
/A,r
6, FrRST •
US 264 pC4 FIFTH
• \(-PS Z TFNTH
r`'t, o . w -- �33
N
Eastside Tank
a Q
0 Southside Tank
Southeast Tank
u513 n
- '' - " t...1i,.."'lir O t---7-, tw
♦ Q%. C
_< n
w
0 1 2
0 MAIN m
Miles
Figure 5-16: System Pressure with 2025 Peak Hour Demand, Steady State, Pumps Set
to Maximum Day Demand, and Tanks 50% Full
Hazen and Sawyer I Water Distribution System Model Update 5-30

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
J%i(ti/tMsle Wp,s44G1.O14 Legend
N 0 Treatment Plant
0 Existing Tank
0 Prop 2020 Tank
y� . Prop.2040 Tank
Pipe
Peak Hour Pressure
1 iii
<20 Psi
14, ,, -
• 20-35 psi
35-40 psi
40-80 psi
• >80 psi
4
ciP
N4G
: it,
4
,„ 7 F
Ai
114 . . ,
.1.111111
OQ' Water Plant cc C,o(US
/'cT,S, .FiRSt _ Y
US 264 '. O� FIFTH ,,,
O\G���S 2 rFHTy
Q
Eastside Tank
C
a 0 0 Southside Tank
W Southeast Tank
vs 1� n
0
G
-4 Z
= w
0 1 2
Z MAIN ' m
Miles
Figure 5-15: System Pressure with 2020 Peak Hour Demand, Steady State, Pumps Set
to Maximum Day Demand, and Tanks 50% Full
Hazen and Sawyer I Water Distribution System Model Update 5-29

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
205 - r - 250
200 1 ta raJ _ 200
_ //'
\b„ � as
- 195 -- - T
- 150 0
rn
a . 1 gli
ea a) . / as 2
2
190 -/ % • - 100 tn.c
con a
185 ‘� L \ i_ - 50
180 0
12:00 AM 6•.00 AM 12:00 PM 60 PM 12;00 AM 6.00 AM .12:00 PM 60 PM 12••p0 AM
Eastside Tank Westside Tank Southeast Tank
—Southside Tank —Flow Supplied —Pumping Head
Figure 5-13: 2040 Maximum Day Demand Extended Period Simulation Results
205 - r 250
200 - 200
c
195 - -o
I
' _ El
150 E m
185 - =
a 3
_o
:I - 50 u_
180
175 0
12 p0 PM 6:00 PM A2.0 PM 6:00 PM 12•00 PM 6:00 PM 12:00 PM 6:00 PM 12.00 1
-EAST_SIDE(ft) NEW WEST(ft) SOUTHEAST(ft)
—SOUTH_SIDE(ft) —Flow Supplied Pumping Head
Figure 5-14: 2050 Maximum Day Demand Extended Period Simulation Results
Hazen and Sawyer I Water Distribution System Model Update 5-28

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
205 F 250 '
200 1 \,\„/1 200
- 195 / Istkpoi,,,,, , i00 ,_::: Jj
2 190
c 0)
ca 3a
I- o
185 50 i
180 0
1200 PM 6.00 PM12:009M 6.0091\f‘
12:00 PM 6.00 P34‘
12009M 6.00PM12.00 PM
Eastside Tank --Southeast Tank Southside Tank
—Flow Supplied ------Pumping Head
Figure 5-11: 2025 Maximum Day Demand Extended Period Simulation Results
205 - - 250
200 200
. a
I
195 - as
CD
190 - - 100 a'a
7
a
o
185 - 50 u-
[..,
180 0
12.00 PM 6:00 PM 12.00 PM 6:00 PM 120 PM 6:00 PM 12:00 PM 6.00 PM 12:00 PM
-Eastside Tank Southeast Tank Southside Tank
—Flow Supplied Pumping Head
Figure 5-12: 2030 Maximum Day Demand Extended Period Simulation Results
Hazen and Sawyer I Water Distribution System Model Update 5-27

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Table 5-7: Tank Hydraulic Grade Line Differences and Maximum Pressures
for Existing and Future Scenario Extended Period Simulations
Maximum Tank HGL Maximum Nodal Pressure
Year Difference (feet) (psi)
2015 1.9 110
2020 4.3 103
2025 4.3 102
2030 2.4 102
2040 2.9 99
2050 4.8 104
2020 Partial 1 10.9 116
' 2020 partial results include partial improvements.
205 - r r r - 250
200 -- /
f - 200
a
195 150
C
a g
CD
as E as
m 190 - ' 100 -a I
a)
c >
- v
a
(a as
185 - 50 Cl-
.
0
ii
180 0
12.0° PM 6:03 1 12.0°PM 6.0°PM 12.0° PM 6.0° PM 12.00 PM 6.00 PM 12.0° PM
Eastside Tank Southeast Tank -----Southside Tank
—Flow Supplied Pumping Head
Figure 5-10: 2020 Maximum Day Demand Extended Period Simulation Results
Hazen and Sawyer I Water Distribution System Model Update 5-26

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
5.7.2 Future System Performance with Recommended Improvements
The results of a maximum day demand extended period simulations for future scenarios with proposed
improvements are illustrated in Figures 5-8 through 5-12. Tank hydraulic grade lines are balanced within
5 feet of each other for all scenarios. Pressures under peak hour and maximum day demand conditions are
illustrated in Figures 5-13 through 5-17. Pressures are greater than 40 psi in the vast majority of the system
for all scenarios. Some nodes, mainly in the southwest and far northern portions of the system, experience
pressures between 35 and 40 psi. All predicted nodal pressures are greater than 35 psi.
As with existing conditions, the model predicts the highest pressures in the northern portion of the system
near the WTP. Maximum pressures reached during the extended period simulation for each future scenario
are summarized in Table 5-7. Maximum pressures are predicted to decrease in comparison to existing
conditions with the proposed improvements, which will reduce stress on pipes and improve system
reliability.
Water age for each future scenario in an average day, low-demand year, without flushing, is illustrated in
Figures 5-18 through 5-22. In 2020, 2025 and 2030, water age is the highest in the vicinity of the Southside
and Eastside tanks and in the southwestern portion of the network due to residence time in the tanks and
distance from the WTP. In comparison to existing conditions, water age in the southeastern portion of the
system is lower and water age in the southwestern portion of the system is higher. This is largely a function
of the fresh water being delivered to the eastern portion of the system via new transmission and the
addition of 2 MG of storage, thereby almost doubling the current system storage at 2020. As demands
increase and transmission capacity is eventually added in the western portion of the system, the overall
water age is improved.
High water age is also observed in the far northern portion of the water system near the Town of Bethel.
This is a function of demand in that area and is not effectively addressed with strategies other than
increasing demand at the north end of the lines. Therefore, this area should be monitored and continuation
of flushing in that area may be required. The demand in this area is influenced by the fact that Bethel does
not receive all of its water from GUC, exacerbating the low demand conditions in the northern portion of the
system. Consideration should be given to the benefits of GUC supplying all of Bethel's demand, which
could reduce the need for flushing in this area. Under a separate project, Hazen is assisting GUC staff with
an evaluation for its acquisition of Bethel's system and water supply options to Bethel are being considered
as part of that separate study. Hydraulic modeling conducted by Hazen as part of that evaluation has
indicated that the 12-inch connector main proposed near Bethel for 2525 may exacerbate water age
problems in that area of the network. Once it has been decided how much of Bethel's demand GUC will
supply in the future, hydraulic conditions in this area of the network should be reevaluated to determine
how redundancy and capacity could be improved while keeping water age as low as possible.
t I Water Distribution System Model Update 5-25

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
�y '""I� WASHINGTON Legend
► Utilities
N / � 12' Existing Tank
/ 1 a Prop.2020 Tank
eProp.2040 Tank
n WT111 Treatment Plant
Proposed Pipe
Installed 2020
\ Installed 2025
��Installed 2030
\ \ Installed 2040
i
h Installed 2050
w
Existing Pipe
1 <12"
NG L22 h Gcp3 12'-18'
N 18'-24'
,01
• eaaaae>24"
ye,LP / 6F�` a .0P3ON
O S
/ (v2Zv /�Q\
1 wit. Water Plant w '•-/04Vs US 264
to r 3 -
tr
It ' Fir,. °
US 264 ;e. Vs F*r ,5O aA e^yTENTf
etc
ti , tiY- Eke to_ '�W1 ' G
e �! "'P
.,. ii, i N • L�',_� 1 wr(-t, Eastelde,Tank''
M
Westslde Tank t. S ..(1, t a • '• �I)cr.
Southside Tank: L=_ -
2�:' ' E ,'� Southeast Tank
1r u n2 n
'w
MAIN =
U >
0 1 2 z z
D
IMII Mileso
Figure 5-9: Proposed Future Transmission and Distribution Mains by Year of Installation
Hazen and Sawyer I Water Distribution System Model Update 5-24

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
5.7.1.2 Proposed 2030 Improvements
Proposed improvements in 2030 include a 36-inch transmission main heading west from the WTP along
Old River Road and then south across the Tar River parallel to the U.S. 264 Bypass. This transmission
main will parallel an existing 24-inch main crossing the river. The proposed main, ending at U.S. Hwy 43,
will increase transmission capacity across the river and provide more supply to the western side of the City.
These proposed improvements will enable a hydraulic balance with the eastern side.
A 24-inch north-to-south transmission main is also proposed for 2030 in the southwestern portion of the
system. This main is located along Frog Level Road. This main will convey supply south from the existing
24-inch main along Dickinson Avenue to areas with increasing demand.
5.7.1.3 Proposed 2040 Improvements
Proposed 2040 improvements include a 36-inch transmission main extending the 36-inch main added in
2030 east along U.S. Hwy 43 and south along W. Arlington Boulevard to the intersection with NC-11 S.
From that intersection, a 24-inch transmission main is proposed heading south along NC-11 S. and ending
at Regency Boulevard where the main will connect to the 24-inch main added in 2025. These 36-inch and
24-inch mains will increase supply to the southwestern portion of the system. Along with transmission
mains proposed in earlier phases, these mains will complete a loop around the service area.
A 12-inch distribution main in the southeast area of the system along County Home Road and a 12-inch
distribution main in the northern part of the system are also proposed for 2040. These distribution pipes will
supply growing demand in the far reaches of the system and maintain adequate pressures in those areas.
A 2 MG Westside elevated storage tank is also proposed for 2040 near the intersection of S.W. Greenville
Boulevard and the Dickinson Avenue Extension (U.S. Hwy 13). No new transmission mains connecting to
the new tank are proposed for 2040; however, the new tank will be connected to the rest of the network via
the existing 24 and 20-inch mains that intersect at that point. This new tank will provide storage for the
southwestern portion of the system, which is far from other tanks and is expected to experience substantial
demand growth in the future.
5.7.1.4 Proposed 2050 Improvements
Most of the proposed 2050 improvements are 12 to 20-inch distribution mains to improve distribution
capacity in the northwest, southwest, and southeast areas of the system. A 16-inch transmission main is
also proposed along Dickinson Avenue to increase supply to the Southeast Tank installed in 2040 by
connecting this tank to the 36-inch transmission main along Arlington Road.
Hazen and Sawyer I Water Distribution System Model Update 5-23

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
5.7 Evaluation of Future System Improvements and Phasing
The model evaluated future transmission mains and system performance. High service pumping is integral
to the recommendations and evaluations for future transmission mains. The proposed improvements are
phased by year, but are sized based on anticipated water demand in that year. Figure 5-7 provides an
illustration of the proposed transmission mains and storage tanks by installation year.
5.7.1 Proposed 2020 Improvements
Installation of a 48-inch transmission main from the WTP high service pump station to Old River Road is
proposed for 2020. This proposed main will reduce velocity and headloss in the parallel existing 36-inch
main leaving the WTP. The existing 36-inch main currently carries all flow leaving the high service pump
station.
Installation of a new 30-inch transmission main is proposed starting at the intersection of Highway 13 and
West Belvoir Highway, east along Pactolus Highway, then south along Greenville Boulevard N.E., and
crossing the Tar River on the eastern side of the City. The proposed 30-inch main will connect to a
proposed main heading east along E. 10th Street, then south along Portertown Road, and west along
E. Fire Tower Road to a proposed 2 MG Southeast elevated storage tank near the intersection of E. Fire
Tower Road and Charles Boulevard. The transmission pipes and tank will provide storage and supply for
anticipated demand growth in the southeastern portion of the network.
The 2013 Water Distribution System Master Plan called for all additional transmission across the Tar River
to be on the western side of the City. However, anticipated wholesale flows to Farmville have decreased
since that plan was developed and significant growth is projected in the southeastern portion of the city.
Transmission capacity in the eastern side of the City is therefore a priority. There is a lack of transmission
capacity in the eastern and southeastern portion of the service area. A 16-inch transmission main is
proposed to connect the Eastside and Southeast Tanks to promote hydraulic balance between the two
tanks. A proposed 20-inch transmission main heading southwest from the Southeast Tank helps to balance
that tank with the Southside Tank and also increases supply to the southwestern portion of the system.
This proposed approach establishes a nearly complete transmission loop around the system providing
reliability and flexibility in the system.
5.7.1.1 Proposed 2025 Improvements
Improvements proposed for 2025 include 20-inch and 24-inch transmission mains continuing west along
Fire Tower Road from the 20-inch transmission main installed in 2020 and then north along NC-11 S.
These mains will reinforce supply to the southwestern portion of the system where substantial demand
growth is anticipated and additional transmission and distribution capacity is proposed for future years.
A 12-inch transmission main connecting existing mains on U.S. 64 Alternate and NC-11 in the far northern
part of the system is also proposed in 2025. Connecting these two long mains will provide redundancy and
make it possible to increase supply to both the far northeast and far northwest portions of the network by
increasing transmission capacity along Porter Road.
Hazen and Sawyer I Water Distribution System Model Update 5-22

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
I0
Greenville r--s_ „ Legend
Utilities
�� O Active Flusher
Z
(J Inactive Flusher
/ 0 e Existing Tank
: e Prop.2020 Tank
` e Prop 2040 Tank
`- f 11 Treatment Plant• I�'
., tic Water Age
�� qi % ' <=2days
1
AF04 2-3 days
•
0 it!'■ 3-4 days '/
4-5 days
B 57 days
O� ill
„IN._ _�...,..z.>7 days
•
y
2 I AF58
NC43 .A ,'a...,,�kt
� _I
5 'r '� lUS 2641
,� ;Fa
„_, _ •
,wr . , 4
�. :,.- i'.;,,::,..„:„. to
1 i
� 'fir �+' : :f*•..rrlli
US264 STANr� r •jr—_� ili f�'' i/i�!' •�`
i.
Jam'— R
AF, -*<•''''' ,- IIIII r"..-1111fiii,...." •4:11.%':;::.:111,44 — Ict-4
e . 7 %TIN;•.:17,,„ ,":_ifl..-- ur• rw, t-- ,/44, :
fi , ..--...- Q. ,,,ok et. - .147' -70. ,•4t
' "- -eit ,k44,-,Inii . . . 1
AFor II.: -
_-. 4 . ..5. Ra-:AF56 ��L iK.� -,•. _
I z-- ,i 111 `2c "s �?
i0 0.5 1
_ . , \
. ' Miles
Figure 5-8: 2015 Average Day Demand Water Age with Automatic Flushing (city center)
Hazen and Sawyer I Water Distribution System Model Update 5-21

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
F,Greenviiie W ASNINGtON Legend
Utilities
N Active Flusher
AF51
OInactive Flusher
. Existing Tank
y e Prop.2020 Tank
n
eProp.2040 Tank
Il Treatment Plant
,AF01 w ` Water Age
�� —<=2 days
2-3 days
3-4 days
\(1 4-5days
N,u`� 5-7 days
N4G
oA >7days
AF
V. itZOO / e, SS' O4
v
O4
v '. .Q
4., i • . �� 46
Q� cr I ICT0 �.
0 _0 G a:'1,w��!S , US 264
�'• AFo6
�'`>y FIRST �r
US 264 r FIFTH
-. --4✓I1,�G� �:�uf ,�, 7.
AFL 41 `r .�...- t NG5
i1 Nib _ ,.
� ,, �/; A f � �. O Eastside Tank
1-0‘
�t�
1' •AF South Ade9 t 1 ,7
5',5 • s
' � • ft
V i., r,4 'T I( .she r .00
1 ' . C
d'' < n
s n
U
MAIN o
0 1 2 z m
Miles
Figure 5-7: 2015 Average Day Demand Water Age with Automatic Flushing
Hazen and Sawyer I Water Distribution System Model Update 5-20

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
Greenville I Legend
Utilities
O Active Flusher
z
OInactive Flusher
r` #14
® Existing Tank
1 ® Prop.2020 Tank
F < Prop.2040 Tank
e
r ® Treatment Plant
Water Age 1
1`=•� ~% \ it ----_ <-2 days
AF04 2-3 days
• �..� 3-4days 14-5days
5-7 days
i
411 50:0 >7 days
y -= -or I, ir
• ��_ 111Ni;
` ARMI • //! / AF42 A 6
..• .gi../.1i.. "-1 CrbP
NC 43 Ara�� '� 1US 264
II
may.•,I y t ��o ,,
hill Alf li 115;;Lf ZII:n7i.
S US-264 STANTO stiiV es C:1::7.�Ii,,!1 ;=
_� ;�_II�l1ar
!, fir{ y. �y 1/114, c64,....:;4‘,,,,,�s. `
Cii, <11 711111,' 1 /' fa I.IN. 4
A�� ♦ g IJrl`\ • ti : , . , 0' -
,.__ le' 1, -,..11 tiFiii,:),_40,‘,111s,awil -;-. : ''' , :_,..:
Ale' 0'
4
ie . 1 4 .4-r. - - e. .., ,,,,
1-k ,c, d
o 0.5 1 j 1 5.. , cn
El= Miles
j c t j.
t -444...../ i 7' ila ..osik - ,
Figure 5-6: 2015 Average Day Demand Water Age without Automatic Flushing (city center)
Hazen and Sawyer I Water Distribution System Model Update 5-19

Preliminary Engineering Report
Phase 1 Water Treatment Plant Improvements
Greenville Utilities Commission
SItiesile SNtNGTON
utilities wA Legend
N ., 0 Active Flusher
AF61
• .---j Inactive Flusher
QExisting Tank
f O Prop 2020 Tank
n
, O Prop 2040 Tank
1* Treatment Plant
;, dAFO1 W Water Age
\si>4.s...,"----11 <=2 days
2 3 days
3-4 days
4-5 days
N/,C+Itill 5-7 days
V AF
fil
you+ •;�``o ' 1 .SIFa
SI
1`"
4
411:r 1
?
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Hazen and Sawyer I Water Distribution System Model Update 5-18

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and Tanks 50% Full
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205 - r r 250
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Figure 5-3: 2015 Maximum Day Demand Extended Period Simulation Results
5.6.2 System Pressure
System pressures with 2015 maximum day and a peak hour demand of 27.5 mgd are illustrated in
Figure 5-4. The modeling results demonstrated that the system will maintain a minimum pressure greater
than 40 psi at all points in the system. The northern bank of the Tar River experiences the highest
maximum pressures due to the low ground elevation and high hydraulic grade level near the WTP. The
maximum pressure reached in that area during the extended period simulation was 110 psi.
5.6.3 Water Quality Performance
Figures 5-5a and 5-5b illustrate estimated water age for the 2015 average day scenario without automatic
flushing. The highest water ages are predicted in the southeast and northwest portions of the system. High
water age in the southeast may be caused by low demand in the area and its location downstream of the
Southside and Eastside storage tanks. High water age in the northwest is likely due to its distance from the
WTP and low demand. With the exception of isolated situations where dead-end mains or pipes with low
demands exist, in general the water age in GUC's system is less than three days and did not demonstrate
any systemic water quality concerns as a function of water age. Figures 5-6a and 5-6b illustrate estimated
water age for the same 2015 average day scenario but with automatic flushing. Water age in the network
overall is similar with and without the flushers; however, some of the flushers (eg. flushers 4, 8, 46 and 58)
provide a notable reduction in water age at the specific locations where they are installed.
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5.5.2.2 Extended Period Maximum Day Demand Hydraulic Simulations
Extended period simulations were conducted to assess how tank levels fluctuated when the system was
subjected to the maximum day demand diurnal demand pattern. High service pumps were controlled to
turn on and off based on tank levels so that tanks would fluctuate between approximately 60 percent full
and approximately full during each 24-hour period. The simulations were run for 96 hours, with data
recorded during the last 48 hours. The same extended period simulations were used to estimate maximum
system pressures.
As with steady state peak hour simulations, extended period simulation results include maximum day
demand in the Greenville and Winterville systems with no wholesale demand. Simulations were conducted
with 90th percentile demand in Greenville and Winterville and maximum day demand from other wholesale
customers to ensure system performance under those conditions.
5.5.2.3 Extended Period Average Day Water Age Simulations
For the extended period water age simulations, the model was set to operate under average day demand
conditions with the average day diurnal demand pattern. Because water age increases as demand
decreases, average day demand for a wet(low-demand) year was used to produce a conservative
estimate of water age. High service pumps were controlled to turn on and off based on tank levels so that
tanks would fluctuate between approximately 60 percent full and approximately full during each 24-hour
period.
The water age simulation module of the distribution system model calculated the water ages in the
distribution system with an extended period simulation of 720 hours (30 days)to achieve water age
equilibrium. The model's water age predictions are meaningful only after equilibrium is established, so the
model output for the final 24 hours of simulation was used to represent the average water age.
To evaluate the effectiveness of the automatic flushing program, water age simulations for the existing
system were conducted with and without the automatic flushers. Water age simulations for future scenarios
did not include automatic flushing.
5.6 Evaluation of Existing Distribution System Performance
5.6.1 Tank Balancing
GUC's current distribution network results in good hydraulic balance between the two existing tanks.
Modelled conditions included a maximum head difference of 2 feet between the two tanks during an
extended period simulation with a maximum day demand of 21 mgd. Figure 5-3 provides an illustration of
the 2015 maximum day demand extended period simulation results.
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5.5.1.2 System Pressure
The North Carolina Administrative Code (NCAC) requires that elevated storage tanks be designed to
provide at least 20 pounds per square inch (psi) during fire flow conditions and 30 psi during peak flow
conditions. In general, the minimum target pressure for the water distribution system is 35 psi at ground
level at all points in the system during peak hour conditions without fire flows including at the highest
ground elevations in the service area. However, during fire flow events, the water pressure should not fall
below 20 psi at any hydrants in the systems. The maximum pressure target in the system is 110 psi, the
currently predicted maximum pressure. Much of GUC's system is PVC, pressure tested to 150 psi at
installation. Therefore, avoiding increasing pressures beyond the current maximum is important to
maintaining system integrity and reliability.
5.5.1.3 Water Age
A typical water quality index in distribution systems is water age. Water age in the distribution system refers
to the travel time of water after leaving the clearwell of the WTP and before entering the customer's
plumbing system. Water age is considered a major variable linked to water quality deterioration in drinking
water distribution systems. As water travels through the distribution system, it undergoes various chemical,
physical and aesthetic transformations that affect water quality. The longer water resides in the distribution
system, the greater potential for water quality transformation.
5.5.2 Model Simulations
Three types of model simulations to include steady state hydraulic, extended period hydraulic, and
extended period water age were conducted for the existing distribution system and for future scenarios.
5.5.2.1 Steady State Peak Hour Demand Hydraulic Simulations
Steady state hydraulic simulations were conducted to estimate system pressures under peak demand,
when the system is expected to experience the lowest pressures. For these scenarios, the demand was
set to peak hour demand on the maximum demand day for a dry (high-demand) year. High service pumps
were set to provide maximum day demand flow (but not peak hour flow). Distribution tanks were set at
50 percent full, their lowest anticipated operating level.
With the exception of Winterville, GUC can curtail supply to wholesale customers when GUC's system is
experiencing high demands. Peak hour scenarios included maximum day demand in the Greenville and
Winterville systems and no demand from other wholesale customers, since those conditions represent the
highest anticipated total demand. Peak hour scenarios were also conducted with 90-percentile demand in
Greenville and Winterville and maximum day demand from the wholesale customers to ensure sufficient
storage, transmission, and distribution capacity. Results from those"90%+wholesale" scenarios are not
included in this PER, but also showed acceptable system pressures.
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5.4.2.2 New Elevated Tank Locations
The first proposed 2 MG tank is recommended to be located in the southeastern sector of the distribution
system, in the vicinity of the intersection of East Fire Tower Road and Charles Boulevard based on an
assessment of the current GUC water system, the anticipated distribution of future development, and
model simulations. The second 2 MG tank is proposed near the intersection of Dickinson Avenue and
Greenville Boulevard. These locations were chosen for the following reasons:
• Proximity to a high demand area.
• Favorable ground elevations.
• Undeveloped properties for elevated storage.
• Proximity to major existing/ proposed transmission mains.
• Good performance with the existing elevated storage tanks.
The 2013 Water Distribution System Master Plan included one proposed storage tank at Dickinson Avenue
and Greenville Boulevard due to Farmville's anticipated high demand for wholesale water. Since the 2013
Water Distribution System Master Plan, Farmville's projected demand has decreased. For this reason,
storage is proposed to be built first in the southeast portion of the distribution system. Both proposed tanks
will be on the same hydraulic grade line as the two existing elevated tanks and will have satisfactory
hydraulic performance in conjunction with proposed transmission mains.
5.5 Modeling Methods Used to Evaluate System Performance
5.5.1 Design Criteria
The performance of the current and future water distribution system with recommended improvements was
evaluated by conducting hydraulic and water quality simulations. In addition to criteria for pumping capacity
and storage capacity, distribution system performance was evaluated based on tank balancing, system
pressure, and water age. Fire flows were evaluated in detail in the 2013 Water Distribution System Master
Plan and were not revisited as part of this PER. Model comparisons to design criteria identified issues in
the distribution system and established an improvement program to reinforce the existing system to meet
projected water demands through the year 2050. With well-defined design criteria, a water distribution
system will maintain appropriate system pressures, appropriate system reliability, optimized system
operation cost, and acceptable water quality.
5.5.1.1 Tank Balancing
The transmission and distribution system should be designed such that transmission capacity toward a
given area of the network is proportional to demand in that area of the network. Since GUC's network
operates with one pressure zone, all tanks in the network should have approximately the same water
surface elevations under the range of expected operating conditions. Future transmission piping was
designed to minimize hydraulic grade line differences between tanks.
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The requirements for emergency storage in the planning period are provided in Table 5-6 for the GUC
service area. The existing 2.5 MG of elevated storage and 6 MG of clearwell storage at the WTP were
considered for a combined capacity of 8.5 MG. This existing capacity would be sufficient to meet
emergency storage needs through 2025. If the addition of the two 2 MG tanks is considered sufficient, then
emergency storage would be available through 2040. However, as detailed in Section 15, additional
clearwell capacity is proposed at the WTP to attain adequate disinfection contact time. This additional
storage capacity is included in Table 5-6, with a 3 MG clearwell added by 2020 and another 3 MG clearwell
added by 2040, which results in surplus emergency storage through the year 2050.
Table 5-5: Summary of Distribution Storage Analysis for GUC Service Area Only
Total
Equalizing Fire Flow Storage Existing Existing and Surplus
MDD 1 Storage 2 Storage 3 Needed Storage Proposed Storage
Year (mgd) (MG) (MG) (MG) (MG) Storage (MG) (MG)
2015 20.3 1.8 0.6 2.5 2.5 2.5 0
2020 23.5 2.1 0.6 2.7 2.5 4.5 1.8
2025 25.7 2.3 0.6 2.9 2.5 4.5 1.6
2030 28.2 2.5 0.6 3.2 2.5 4.5 1.3
2040 35.6 3.2 0.6 3.8 2.5 6.5 2.7
2050 46.1 4.1 0.6 4.8 2.5 6.5 1.7
MDD is based on maximum day demand in GUC system on a dry(high-demand)year with other wholesale demands
curtailed
2 9%of MDD(from summer 2010 diurnal curve).
3 3.500 gpm for 3 hours(AWWA M31).
Table 5-6: Summary of Emergency Storage for GUC Service Area Only
Needed Existing Existing and
ADD Emergency Storage Proposed Surplus Storage
Year GUC (mgd) Storage (MG) 1 (MG) Storage (MG) (MG)
2015 13.2 6.6 8.5 8.5 1.9
2020 15.3 7.6 8.5 13.5 5.9
2025 16.7 8.4 8.5 13.5 5.1
2030 18.3 9.2 8.5 13.5 4.3
2040 23.1 11.6 8.5 18.5 6.9
2050 29.9 15.0 8.5 18.5 3.5
Half of ADD(per DEQ).
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Storage requirements were evaluated for the GUC distribution system using two criteria. The first criterion
is that the storage capacity should exceed the combined storage requirements for equalizing and
firefighting. For firefighting, a maximum required fire flow of 3,500 gallon per minute (gpm)with a duration
of three hours was assumed (per AWWA Manual M31), which corresponds to a fire storage volume of
0.63 MG. The second criterion is defined by DEQ. Storage in the system should exceed half the demand
for an average day. Emergency storage can include distributed storage (e.g., elevated in GUC's system)
and clearwell storage, whereas only elevated storage is considered for the combination of equalizing and
fire flow storage requirements.
Determining the size and location of storage facilities is an important part of distribution system planning. If
additional storage is recommended based on the evaluations, the following factors need to be considered:
• The location of the proposed storage facility(close to transmission mains, high ground
elevation, dense demand area).
• The capacity of the proposed storage facility.
• The relative economics of constructing additional pumping and transmission facilities
versus additional system storage facilities.
• Impact on hydraulic performance of the existing storage facilities.
• Impact on water quality, specifically water age.
5.4.2 Current and Future Storage Requirements
supply requirementsY
Storage for GUC's water su I system in 2015, 2020, 2025, 2030, 2040 and 2050 were
calculated. Only demand within the GUC service area was considered in calculating storage requirements.
It was assumed that wholesale customers will provide their own storage capacity for emergencies and fire
flows. The required storage was compared to the existing storage capacity. If a storage deficiency was
identified, new storage was proposed to ensure sufficient storage capacity for the projected demands.
5.4.2.1 Volume Analysis
Table 5-5 provides the storage requirements for equalizing and firefighting for the planning period. Only
elevated storage in the distribution system was considered for equalizing and firefighting. The two existing
elevated storage tanks are marginally sufficient to meet the equalizing and firefighting storage requirement
of 2.5 MG for warm and dry (high-demand) conditions at 2015 demand levels. As demand increases from
present through construction of new storage, deficiencies in storage volumes will exist. Addition of a 2 MG
elevated tank by 2020 and another 2 MG tank by 2040 will meet and exceed equalizing and firefighting
storage requirements through 2050. The proposed tanks would also meet storage requirements if the tanks
were each only 1.5 MG. However, extended period simulations showed that with 1.5 MG tanks, tank levels
would fall below 50 percent if elevated storage is solely relied upon for peak hour demands. Therefore, it is
recommended that 2 MG tanks be constructed.
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Figure 5-2 illustrates the diurnal demand pattern used for GUC's maximum day demand. The curve over
the striped region represents the diurnal demand pattern used for maximum day demand (calculated from
July 7, 2010 SCADA data). The area shaded in solid blue is 9 percent of the striped area, meaning that
required equalizing storage is equal to 9 percent of maximum daily demand.
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Figure 5-2: Maximum Day Demand Diurnal Curve
5.4 System Storage Capacity Evaluation
5.4.1 Storage Requirement Criteria
Water storage is required for equalizing demand, providing fire protection, and supplying the system in an
emergency. Equalizing storage allows water to be supplied at a constant rate equal to the average demand
for the day. Fire storage ensures water is available for the defined duration while production sources and
pump stations supply the projected maximum day demand. Emergency storage is used during main
breaks, equipment failures, power outages, contamination of raw water supplies, or natural disasters that
disrupt normal service.
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Table 5-4: Summary of Location and Operational Condition of Automatic Flushers
Start Finish Flow
Code Location Hydrant Days ' Time 2 Time (gpm)
AF 33 Cambria (Brookhollow) 3393 Su-S 2:00 2:08 157
AF 37 Van Gert 2901 Su-S NA NA NA
AF 39 Landmark church (Dickinson NA Su-S 2:00 4:47 179
Road)
AF 42 Country Squire Est. 1065 Su-S 1:30 1:33 164
AF 43 Mills Street 643 Su-S 1:00 1:02 164
AF 46 Diamond Drive 1996 Su-S 0:30 0:33 180
AF 48 Bradford Park(N.) 2353 Su-S 1:00 1:07 NA
AF 49 Langston Blvd. (Langston Farms) 3221 Su-S 2:00 2:03 100
AF 51 Bethel Interconnect NA Su-S NA NA NA
AF 53 Norcott&Gooden 519 Su-S 2:30 3:54 224
AF 54 Howell Street 545 Su-S 1:30 2:45 134
AF 55 Kennedy Circle 522 Su-S 1:00 1:40 1500
AF 56 Merriwood Lane 1797 Su/T/Th/S 2:00 2:55 180
AF 57 Copperfield Lane 2404 M/W/F 2:00 3:00 172
AF 58 North Creek Drive 3560 M 1:00 1:45 157
AF 59 E. Baywood Lane 3553 Su-S 1:00 1:04 97
'"Su-S"means that a Flusher is operated every day, Sunday to Saturday.
2AII times provided are AM.
3 Information marked as"NA"was missing from data provided by GUC staff. When hydrant number was not available
the flushing demand was assigned to a node near the location given. Flushers for which no flow was given were
assumed to not be operating.
5.3.4 Diurnal Demand Pattern Setup
Diurnal demand patterns are defined in the model to generate hour-by-hour demand variations in the
distribution system. The patterns are critical for accurately calculating velocities, travel times, and tank level
changes for extended period simulations. As part of GUC's 2013 Water Distribution System Master Plan,
SCADA records from 2010 were used to calculate diurnal demand patterns. Those same demand patterns
were applied to node demands for modeling current and future conditions in this project. Separate patterns
were used for average day conditions and maximum day conditions.
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5.3.2 Future Demand Allocation
Future demands were allocated to existing model nodes based on projected demand growth in TAZ (refer
to Section 3.6). For each future year analyzed, current demand at each node in the model was scaled up
proportionally to projected demand growth in the TAZ in which the node was located. Some model nodes
(representing approximately 3 percent of the 2015 demand) were not located within TAZ. Demand growth
at these nodes was assumed to be proportional to demand growth in the GUC service area. The GUC
service area was assumed to stay within the current boundaries through 2050 (refer to Section 3.7), so
future demand was allocated without adding any new demand nodes to the model.
The aforementioned demand allocation method resulted in portions of future demand located at several
existing nodes impractical for the supply of additional demand. For example, in a few cases future demand
was placed at the end of 2-inch dead-end mains near vacant parcels, resulting in excessive headloss and
low pressures that does not reflect how system implementation would occur. In these cases, demand was
manually reallocated to nearby nodes better able to supply the demand. Future demand allocation in the
model is an approximation and can be refined as growth patterns become more apparent and can be
allocated using billing records.
5.3.3 Demand from Automatic Flushers
Demands from GUC's automatic flushers were added to the model at the hydrant nodes where the flushers
are located. Diurnal patterns were applied to the flusher demands to approximate the flushing schedules.
Demand from automatic flushers was only accounted for in water age model simulations. Automatic
flushing is not expected to have a significant impact on maximum or minimum system pressures, because
average daily flushing volume is only 0.15 million gallons. Table 5-4 summarizes the locations and
operational conditions of GUC's automatic flushers.
Table 5-4: Summary of Location and Operational Condition of Automatic Flushers
Start Finish Flow
Code Location Hydrant Days 1 Time 2 Time (gpm)
AF 01 Silver Creek 2755 Su-S 4:00 4:10 142
AF 04 Staton House Road 2035 Su-S 2:00 2:10 116
AF 05 Bradford Creek. (Brandenburg ) 2171 Su-S 4:00 4:10 194
AF 08 Stantonsburg Road 1872 Su-S 3:00 3:20 142
AF 09 Allenridge (Ellery-cul de sac) 3149 Su-S NA3 NA NA
AF 12 Landover(Sweetbay) 3487 Su-S 4:00 4:10 172
AF 14 Flagstone Drive (Cobblestone) 3242 Su-S 1:00 1:05 150
AF 16 Brookville Drive (Cobblestone) 3375 Su-S 2:00 2:10 160
AF 17 Millcreek (Megan Drive E.) 3094 Su-S 1:00 1:03 180
AF 19 Bristolmoor 3210 Su-S 2:00 2:04 217
AF 20 Emerald Park (Jade E.) 3329 Su-S 1:30 1:50 75
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The current demand at each node of the model was allocated based on billing records associated with the
water meters surrounding the node, plus the non-revenue generated water. The billing record approach
assured demands were disaggregated to each node in the grid system, thereby ensuring the most
accurate flow calculations in small pipes. This approach also enables GUC to easily update the demand in
the model for subsequent studies. The distribution of water usage in GUC's water service area is illustrated
in Figure 5-1. Each yellow dot represents a water meter with GUC billing data. Each purple dot represents
a water meter with Winterville billing data.
Demand calculated from billing records was adjusted for non-revenue water. Non-revenue water is the
difference between the total water billed and the total flow leaving the water plants. Therefore, demand was
distributed using billing records but the total demand in the model matches production records. The
average production in 2015 was 12.8 mgd and the total from billing records was 11.1 mgd. The difference
of 1.7 mgd, or 13 percent, represents non-revenue water. Non-revenue water may be caused by either
physical losses due to leakage in the system, administrative losses due to illegal connections and under
registration of the water meters, or activities such as hydrant flushing, or fire training. This percentage of
non-revenue water is in the normal range compared with other utilities in North Carolina. The non-revenue
water was distributed in the model by proportionally adjusting each node's demand.
Diurnal demand patterns are defined in the model to generate hour-by-hour demand variations in the
distribution system. The patterns are critical for accurately calculating velocities, travel times, and tank level
changes for extended-period simulations (EPSs). Diurnal demand patterns are calculated based on the
hourly pumping rates and tank levels from SCADA of a typical summer day in 2015.
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Model nodes (e.g., network junctions)were also recreated at the ends of pipe segments. Elevations were
automatically assigned to the model using the NCDOT LiDAR data downloaded from NCDOT website
(release date May 2007). Each node was assigned one or several kinds of demands. Current demands
were distributed based on 2015 billing records. The pump stations and storage tanks in the model remain
the same.
5.2.4 Ground Storage in Model
Prior to the model updates as part of this project, the high service pump station was modeled as a facility
pumping from a static reservoir offering unlimited supply. This is typical of distribution system models, as it
is generally assumed that plant capacity can be adjusted to maintain a desired clearwell level. In this
project, the model was updated to include the WTP clearwell, which allows for the evaluation of diurnal
clearwell levels in combination with high service pumping.
In the updated model, water is pumped to the clearwell at a constant rate(set to the daily demand of the
scenario being run)from a reservoir representing the WTP. The high service pump station then pumps
from the clearwell. The clearwell is dimensioned in the model to have the same volume and head range as
the GUC clearwell. Where future clearwell storage is planned for specific scenarios, this additional storage
is incorporated into the model.
5.3 Current and Future System Demand Allocation
It is critical to properly distribute water demands in the model to reflect current and future water usage in
the GUC system. The process ensures the accuracy of the hydraulic analysis as well as the water quality
calculations, both of which are dependent on the spatial distribution of demand. Accuracy becomes
particularly critical at extreme ends of the system, such as dead-end pipes. Existing demand allocation was
an automated process of spatially assigning existing water demands to the model.
5.3.1 Current Demand Allocation
The best available information about the location and magnitude of demands in the distribution system is
the utility's meter reading and billing data. Meter readings in year 2015 and service address data were
extracted from the billing system. GUC staff provided 2015 monthly water billing data from all 36,424
customer meters. The annual average day demand (ADD)for each user account was summarized and
assigned to a corresponding water meter points in GIS. Using this meter point GIS layer, water demand
was allocated to the nearest model junction using the Demand Allocator, a built-in function in InfoWater.
Additionally, rules were setup to ensure that only desired nodes are selected for demand assignment.
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5.2.2 C-factor Updates from Recent Field Tests
A comprehensive model calibration was completed in the 2013 Water Distribution System Master Plan.
Only limited calibration was conducted in this model update. C-factor testing and hydrant flow testing
results for GUC's water main rehabilitation project was conducted by Brown and Caldwell in the summer of
2015. The tests were primarily performed in the downtown area on the old cast iron pipes. A summary of
the C-factor testing results is provided in Table 5-3. The measured C-factors from the 2015 tests measured
a wide range of variability and do not reflect a definitive condition for specific materials or installation years.
With the variability reflected in the 2015 C-factor tests, only the C-factors of the specific pipes tested in
2015 were updated in the model. The updated C-factor field data are provided in Appendix A.
Table 5-3: Summary of the Water Main C-factors
from Field Tests in Summer 2015
C-Factor Range Counts
<40 12
40—60 5
60—80 3
80— 100 2
100— 120 2
120— 150 10
> 150 6
5.2.3 Incorporation of Winterville System and Existing Demands
The Winterville system was simulated as a wholesale customer point in the 2013 Water Distribution
System Master Plan. After the 2013 effort, GUC staff added the Winterville distribution system into the
GUC model. Similar to the GUC system portion of the model, significant pipe network changes were
observed by comparing the model network and the most recent Winterville pipeline network GIS file. In
addition, the existing demands in Winterville system required updating.
Using the same approach as the GUC system portion of the model, Hazen and Sawyer updated the
Winterville system model by replacing the entire pipe network with the most recent Winterville pipeline GIS
data. Pipes were imported into the model from the GIS files using the built-in tool of InfoWater software.
The pipe IDs currently remain as a one-to-one match to the GIS pipe IDs. Other data attributes, such as
pipe diameter, installation year, and material were carried in the data import process. The pipe lengths
were calculated in InfoWater based on node and bend coordinates. The interior roughness of the water
mains, measured as Hazen-Williams coefficient, was transferred to each pipe from the existing Winterville
model. The GIS data was checked for connectivity problems or pipe size errors using InfoWater built-in
tools.
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Table 5-2: GIS Data Layers Used During Model Construction
GIS Data Layer Data Source Content
Layer from the GUC Water GIS layer contained all existing pipes as
GUC water lines System small as 2-inch and included all hydrant
Geo-database (April 2016) laterals.
Layer from the GUC Water GIS layer contained the following water
GUC water symbols System system components: valves, hydrants,
Y Y P Y
Geo-database (April 2016) blowoffs, plugs, reducers, etc.
Greenville topo raster Elevation contour data, which were
NCDOT LiDAR Data (May 2007) assigned to the model using automatic
map functions in InfoWater software.
Data layer contained all of the current
GUC water meter locations. This data
were linked to 2015 water billing data,
Layer from the GUC Water which contained the monthly and yearly
2015 meter locations System consumption statistics summarized for
each meter. Using automatic functions in
Geo-database (April 2016) the InfoWater software, demands were
assigned to the nearest pipe, which
automatically allocated flow to the
connecting model junctions.
Layer from the GUC Water Approximate service area boundaries
Service area System were used to verify which pipes should
Geo-database (April 2016) be included
Aerial photography Aerial photography was utilized to verify
new subdivision development
The pump stations and elevated storage tanks in the model remain identical to the 2013 Water Distribution
System Master Plan model. GUC's WTP clearwells were not included in the 2013 modeling efforts. In this
current work, clearwells were incorporated to allow an assessment of the performance in conjunction with
high service pumping.
The model determines the flows and pressures that would exist in a distribution system under a specified
Y P
set of conditions. The model's facility manager with advanced Active Topology Alternative allows a single
9
model of the water system to be maintained while quickly developing and evaluating an array of modeling
alternatives. Every change cascades through the entire set of projects in an easy-to-use, tree-like structure.
This architecture allows a switch between scenarios, a comparison of input data, a merge of models, and a
comparison of results to illustrate how the system will react to different conditions and planning horizons.
Hazen and Sawyer Water Distribution System Model Update 5-3
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Preliminary Engineering Report
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the model. Additionally, it was noted there were significant numbers of pipes in the new GIS file with
locations shifted away from the locations in the existing model.
Given on the number of pipes in the model need to be updated, Hazen selected to update the model
network by replacing the entire pipe network with the most recent GIS data provided by GUC staff in
April 2016. Similar to the updating approach applied in 2013 Water Distribution System Master Plan, the
pipes in GIS and in the model maintain a one-to-one relationship, while the model and the GIS are
maintained as two separate entities. This approach allows the model and the GIS to share information but
remain separate. General information about the new GUC distribution system model is summarized in
Table 5-1. Table 5-2 describes the data layers obtained from the GUC water distribution geo-database
including the layer name, source, and content.
Table 5-1: Summary of GUC Hydraulic Model Criteria
Parameter Design Criterion
Software InfoWater 12.3
Total number of pipes 33,801
Total number of nodes 32,399
Coordinate NAD 1983 State Plane North Carolina 3200FIPS (U.S. feet)
Model detail All-pipe model
GIS integration One-to-one (matching ID)
Demand 2015 billing data
Ground elevation NCDOT LiDAR data (May 2007)
Pipes were imported into the model from the GIS files using the built-in tool of InfoWater software. The pipe
identification (ID) currently remains as a one-to-one match to the GIS pipe IDs. Other data attributes, such
as pipe diameter, installation year, and material were carried in the data import process. The pipe lengths
were calculated in InfoWater based on node and bend coordinates. The interior roughness of the water
mains, measured as Hazen-Williams coefficient(e.g., C-factor), was transferred to each pipe from the
2013 Water Distribution System Master Plan model in which the Hazen-Williams coefficients were
determined based on the pipe material, pipe age, and field tests conducted by Hazen and Sawyer. The
GIS data was checked for connectivity problems or pipe size errors using InfoWater built-in tools.
Model nodes (network junctions)were also recreated at the ends of pipe segments. Elevations were
automatically assigned to the model using the North Carolina Department of Transportation (NCDOT) Light
Detection and Ranging (LiDAR) Data downloaded from NCDOT website (release date May 2007). Each
node was assigned one or several kinds of demands. Current demands were distributed based on 2015
billing records. Diurnal demand patterns are also part of the node demand data.
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Preliminary Engineering Report
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5. Water Distribution System Model Update
5.1 Background and Objectives
The original GUC water distribution system hydraulic model was developed in 1995 for the Water
Distribution System Master Plan. The model contained 10-inch and larger mains as well as some 8-inch
mains where necessary to complete distribution system loops. The hydraulic model was updated using
H2Onet Analyzer(Version 3.1) software for the 2001 Water Distribution System Master Plan (Black and
Veatch, 2001) to account for changes in the distribution system since 1995. The updated model provided a
more accurate representation of the distribution system than the previous model; however, the model did
not incorporate all individual pipes in the system, particularly those less than 8 inches in size.
In the 2013 Water Distribution System Master Plan project, the water distribution system model was
upgraded to an all-pipe model using InfoWater software (Version 8.5), to incorporate all of the system
pipes, valves, and hydrants from the GIS data. InfoWater also offers hydraulic optimization, fire flow
calculation, calibration tools, energy analysis, optimal pump scheduling, and demand allocation. The
program can create pressure contours, monitor Supervisory Control and Data Acquisition (SCADA)
operations, and run water quality simulations. The 2013 Water Distribution System Master Plan also
included comprehensive field tests to calibrate the all-pipe model.
The current scope of work and project objectives in this PER include the following:
• Model structure updates to reflect the latest GIS information for the system.
• Update of C-factors assigned to pipes based on recent fire flow tests.
• Incorporation of the existing Winterville distribution system network and demands into the
model.
• Incorporation of the ground storage at the WTP into the model to allow assessment of
clearwell levels during operational scenarios.
• Update of existing and future demand allocations.
• Evaluations of system storage requirements.
• Evaluation of existing and future scenarios to establish a recommended long-term Capital
Improvements Plan (CIP) for system improvements.
• Review and assessment of groundwater sources to support GUC needs.
5.2 Model Structure Updates
5.2.1 Model Updates from GUC GIS
Major pumping, transmission and storage facilities in GUC distribution system remain the same since the
2013 Water Distribution System Master Plan. However, significant pipe network changes were observed by
comparing the existing model network and most recent waterline GIS file (dated April 4, 2016).
Approximately 2,000 new pipe segments had been added to the GIS database that required inclusion in
Hazen and Sawyer I Water Distribution System Model Update 5-1

Preliminary Engineering Report
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Table 4-2: Summary of Storage Facility Design Criteria
Volume Depth Overflow
Location/Designation Type (MG) (feet) Elevation (feet)
WTP#1 Clearwell Ground 3.0 35.5 63.5
WTP#2 Clearwell Ground 3.0 35.5 63.5
Eastside Tank Elevated 1.0 40 202
Southside Tank Elevated 1.5 42 202
4.3 Distribution Mains
The distribution mains convey finished water from the water treatment plant to customers through a
network of transmission and distribution pipes. The water distribution system consists of a network of
mains varying in diameter from 2 to 36 inches. Pipe materials include polyvinyl chloride(PVC), steel,
asbestos cement, cast iron, and ductile iron. The oldest pipes in the system have reportedly been
constructed in 1905. According to the 2016 Geographical Information system (GIS) data, the total length of
the water mains is approximately 631 miles.
Hazen and Sawyer I Summary of Existing Water Distribution System 4-5

Preliminary Engineering Report
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Table 4-1: Summary of Well Capacity
Location/ Year Pump Flow Pump TDH Well Capacity Water Quality
Designation Constructed (mgd) (feet) (mgd) Concerns
Eastside 1961 0.33 380 0.17 Fluoride > SMCL
North Greene Street 1970 0.38 400 0.19 Fluoride > SMCL
Iron > SMCL
Washington Street 1957 0.25 330 0.12 High iron
Southside 1969 0.32 357 0.16
Evans Park 1973 0.29 350 0.15
Northside Blending 1999 0.90 ___ 0.45 High iron
Station (total)
TOTAL' 1.76 mgd 0.88
1. The total well capacity excludes Eastside and North Greene St. since these wells have fluoride
exceeding the SMCL.
4.2 Storage Facilities
Water storage facilities consist of two 3 MG finished water storage clearwells at the treatment plant and two
elevated tanks in the distribution system. Treated water is stored in the two 3 MG clearwells at the WTP
until pumped into the distribution system by the high service pumps. The elevated tanks contain water at
the system gradient (elevation 202 feet when full)for equalizing the difference between high service
pumping rates and varying hourly system demands. The elevated storage also provides storage for
supplementing fire flows and for emergency use during power outages or system failures.
Information on the storage facilities is summarized in Table 4-2. There are a total of 6 MG of ground
storage at the treatment plant and 2.5 MG of elevated storage in the distribution system. The tank utilized
at the Northside Blending Station is in an older portion of the system is at a lower hydraulic grade than the
rest of the system and operational with the groundwater wells associated with Northside Blending System.
Therefore, storage at the Northside Blending Station was not considered for the total storage of the system.
Hazen and Sawyer I Summary of Existing Water Distribution System 4-4

Preliminary Engineering Report
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I Greerwille US --___ Legend
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Figure 4-1: Schematic of Greenville Utilities Water Distribution System
Hazen and Sawyer I Summary of Existing Water Distribution System 4-3

Preliminary Engineering Report
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Table 4-1 presents a summary of the relevant data for the distribution wells. Although the total pumping
capacity of the wells is approximately 1.76 mgd, the sustainable well capacity for long-term use is based on
12-hour run times each day at the design flow of the actual well pumps. The total firm capacity of the
distribution system wells is estimated at 0.88 mgd based on the current design capacities; however, the
amount of water that can be withdrawn from the production wells is scheduled to be reduced to 0.3 mgd by
2018 per the CCPCUA rules. While the well system serves a need as an interim, emergency water supply
to the GUC system, very little additional capacity is gained from its long-term use. As such, the wells are
not considered a viable, incremental addition of sustainable capacity to the system. Nevertheless, the
recommended upgrades to the Northside Tank should be undertaken to maintain the reliability of the well
system for interim, emergency water supply needs.
Hazen and Sawyer I Summary of Existing Water Distribution System 4-2

Preliminary Engineering Report
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4. Summary of Existing Water Distribution System
The area served by GUC includes the entire City of Greenville and a portion of the unincorporated area
surrounding the City. The ground elevations within the service area are between 10 feet and 85 feet above
sea level. The distribution system consists of a single pressure zone operating on a hydraulic grade of
202 feet. Figure 4-1 provides a schematic map of the system showing the service area, as well as the
general layout of facilities.
4.1 Water Supply and Pumping
The GUC water system includes three types of water supply sources. These include the water treatment
plant and groundwater wells. ASR was previously investigated as a source of water supply to facilitate
meeting maximum day demands. ASR is not implemented at this time and is not assumed to be a long-
term source impacting water supply needs. The groundwater wells are subject to a 75 percent reduction by
2018 per the CCPCUA rule; however, GUC has banked groundwater that could be used to extend the
opportunities for groundwater supply into the future.
The majority of GUC's water supply is obtained from the Tar River and is delivered to the distribution
system via high service pumping at the WTP. The high service pump station is equipped with four high
service pumps, conveying water from the finished water storage tanks to the distribution system. Finished
water is currently stored and pumped from to the distribution system from two 3 MG ground storage
reservoirs. Additional information regarding existing and proposed high service pumping is addressed in
Section 15.
4.1.1 Groundwater Wells
Eight groundwater wells are available to provide a supplemental water source for the Greenville distribution
system. Five groundwater wells are directly connected to the distribution system and three wells are
associated with the Northside Blending Station. The Northside Blending Station, constructed in 1999,
consists of the Northside, Industrial Boulevard, and Burroughs wells, and the 0.5 MG Northside Tank. The
facilities associated with the Northside Blending Station are considered a single source of water. In 2015,
S&ME preformed a visual inspection on the Northside Tank and provided GUC with a report and
recommendations on its condition. Due to exterior coating delamination, visible interior corrosion, and
breakdown of ladder supports and bolts, S&ME advised the tank be rehabilitated and recoated at an
estimated cost of$0.5M.
Two wells, Eastside and North Greene St., have naturally occurring fluoride exceeding the secondary MCL
of 2.0 mg/L so they are not currently in service. In addition, the North Greene St. well has iron levels
exceeding the secondary MCL of 0.3 mg/L. The Northside Blending Station and Washington St. wells
have high iron levels, so additional treatment may be necessary to provide finished water similar to the
quality produced by the WTP.
Hazen and Sawyer I Summary of Existing Water Distribution System 4-1