NC0021920_Wasteload Allocation_19911121

NPDES DOCIMENT SCANNIN. COVER SHEET
NPDES Permit:
NC0021920
Whiteville WWTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
Correspondence
Owner Name Change
Special Order by Consent
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
November 21, 1991
Thies dacument ism printed on reu+se paper -ignore a.xiy
caYitent on the reverise *aide

NPDES WASTE LOAD ALLOCATION
PERMIT NO.: NC0021920
PERMITTEE NAME:
FACILITY NAME:
City of Whiteville
Whitemarsh WWTP
Facility Status: Existing
Permit Status: Renewal
Major Minor
Pipe No.: 001
Design Capacity: 2.5 MGD
Domestic (% of Flow): 79.6 %
Industrial (% of Flow): 20.4 %
Comments:
average flow over last 12 months is 1.4 MGD, % domestic and %
industrial based on 2.5 MGD and pretreatment flow
RECEIVING STREAM: White Marsh
Class: C-Swamp
Sub -Basin: 03-07-58
Reference USGS Quad: J 24 SW (please attach)
County: Columbus
Regional Office: Wilmington Regional Office
Previous Exp. Date: 3/31/92 Treatment Plant Class: Class III
Classification changes within three miles:
none
Requested by: Rosanne Barona
Date: 10/7/91
Prepared by: AI 4406 ,,. Gl.>yf -> Date: 1 I te\ /'t 1
Reviewed by: N,,L_ ct, ivv-6-7,- Date: (( //
-e oDw 1t /33 (`)-m`iiAltt
(.BSc-L 144
Modeler
Date Rec.
#
SAtA)
l0
8 it
(DO\
Drainage Area (mi2 ) 2-o 1
Avg. Streamflow (cfs): 2,01
7Q10 (cfs) 41 Winter 7Q10 (cfs) 9.1 30Q2 (cfs) to
Toxicity Limits: IWC % Acut
Instream Monitoring:
Parameters -D. D. , Frcc}L Cc tX "MAP, Corr Vacs yip!
Upstream
Downstream Y
Location Ar LEAST 100 / uP5TY2E74711
Location RT RR. CResSiNCt
Effluent
Characteristics
Summer
Winter
BOD5 (mg/1)
5
10
NH3-N (mg/1)
2
4
D.O. (mg/1)
S
5
TSS (mg/1)
30
30
F. Col. (/100 ml)
200
Zoo
pH(SU)
(_g
6-1
oc , i, 412.+ sE Cmcx/.L.)
30 (4a -
,L,i
>c)
30 ( (�o -0A I L y mAY
encomium(/lct/_G)_
— - 11 1
S
1 1 1
l a y
N► c t_. 9 It/L.)VI
L eAb (.p -/L)
CYPNti+r (I'`-/.,
5 5
5 5
1 1
1 '
MEK.cuaN CF.t*l.L
____(2•02 1
11I
0 - 02.-7
AQswic. 9.4 7t.
1 1 1
FLu.OWDIi ( ./ L1
4
4
Comments: FAcILI 7-y
Ztn1c , 5 (1,i1 . •
SYIOUL7) foA)I- oA. CAonAlUAi Co ?Peg-,
PLOTTED
DAILY MAX
VAI Ly nuaX
l7Aft' MAX.
DALL' IM)A
- 1ILY /AM
1IL(nRA.

Facility Name:
NPDES No.:
Type of Waste:
Facility Status:
Permit Status:
Receiving Stream:
Stream Classification:
Subbasin:
County:
Regional Office:
Requestor:
Date of Request:
Topo Quad:
FACT SHEET FOR WASTELOAD ALLOCATION
Request #
Whitemarsh WWTP/ C.O. Whiteville
NC0021920
80% Dom/ 20% Ind
Existing
Renewal
White Marsh
C-Sw
030758
Columbus
WiRO
R. Barona
10/7/91
J24SW
6481
RECEIVED
NOV 8 i i
Wilmfilgten rlegronal Ottied
nC.A
Stream Characteristic:
USGS #
Date:
Drainage Area (mi2):
Summer 7Q10 (cfs):
Winter 7Q10 (cfs):
Average Flow (cfs):
30Q2 (cfs):
IWC (%):
0210910400
1986
201
4.7
9.1
201
10.0
45%
Wasteload Allocation Summary
(approach taken, correspondence with region, EPA, etc.)
Whitemarsh WWTP is compliant with current limits (1 BOD5 violation in the past year). Facility
is implementing a pretreatment program (lretreatment information was available for WLA
evaluation). The plant had overallocated CN, Ni, Hg -- they are required to correct this situation
before they modify any other pretreatment permits.
Instream data indicate D.O. values below 5 mg/1 both up and downstream, with some'values less
than 3 mg/1. This is not uncommon for a swampy area.
0
Special Schedule Requirements and additional comments from Reviewers:
co
CJ1
Recommended by:
Reviewed by
Instream Assessment: (� fly, (X 0 Date:
Regional Supervisor: .�/� Date:
Date: o z
Permits & Engineering: Date: /(/
RETURN TO TECHNICAL SERVICES BY:
DEC O3;59I

2
existing Limits:
CONVENTIONAL PARAMETERS
Monthly Average
Summer Winter
Wasteflow (MGD): 2.5 2.5
BOD5 (mg/1): 5 10
NH3N (mg/1): 2 4
DO (mg/1): 5 5
TSS (mg/1): 30 30
Fecal Col. (/100 ml): 1000 1000
pH (SU): 6-9 6-9 daily max
Recommended Limits:
Monthly Average
Summer Winter WQ or EL
Wasteflow (MGD): 2.5 2.5
BOD5 (mg/1): 5 10 WQ
NH3N (mg/1): 2 4 WQ
DO (mg/1): 5 5 WQ
TSS (mg/1): 30 30
Fecal Col. (/100 ml): 200 200
pH (SU): 6-9 15-9
Residual Chlorine (µg/1):
Oil & Grease (mg/1): 30 30 60 daily max
Oil&Grease is recommended due to its presence from the hospital that discharges to the WWTP.
Limits Changes Due To: Parameter(s) Affected
New regulations/standards/procedures Fecal coli
(explanation of any modifications to past modeling analysis including new flows, rates, field data,
interacting discharges)
(See page 4 for miscellaneous and special conditions, if applicable)

3
Type of Toxicity Test:
Existing Limit:
Recommended Limit:
Monitoring Schedule:
Existing Limits
COD (mg/):
Cadmium (ug/1):
Chromium (ug/1):
Copper (ug/l):
Nickel (ug/1):
Lead (ug/1):
Zinc (ug/l):
Cyanide (ug/l):
Phenols (ug/1):
Mercury (ug/1):
Silver (ug/1):
Recommended Limits
COD (mg/):
Cadmium (ug/1):
Chromium (ug/1):
Copper (ug/l):
Nickel (ug/1):
Lead (ug/1):
Zinc (ug/1):
Cyanide (ug/1):
Mercury (ug/1):
Silver (ug/l):
Arsenic (ug/l):
Fluoride (mg/1):
TOXICS/METALS
Chronic
Chronic Qtrly P/F at 45%
Oct, Jan, Apr, Jul
Monthy Avg
93
monitor
111
monitor
Daily Max.
monitor
111
monitor
195
55
monitor
11.0
0.027
monitor
111
4 mg/1
Limits Changes Due To:
New pretreatment information
Other (onsite toxicity study, interaction, etc.)
WQ or EL
Parameter(s) Affected
all parameters
Ni - new standard
_X_ Parameter(s) are water quality limited. For some parameters, the available load capacity of
the immediate receiving water will be consumed. This may affect future water quality based
effluent limitations for additional dischargers within this portion of the watershed.
OR
No parameters are water quality limited, but this discharge may affect future allocations.

4
INSTREAM MONITORING REQUIREMENTS
uP
Upstream Location: at least 100 ft arosivistream
Downstream Location: at RR crossing (seems to be the only practical monitoring point)
Parameters: D.O., Fecal coli, temperature, conductivity
Special instream monitoring locations or monitoring frequencies:
MISCELLANEOUS INFORMATION & SPECIAL CONDITIONS
Adequacy of Existing Treatment
Has the facility demonstrated the ability to meet the proposed new limits with existing treatment
facilities? Yes V No
If no, which parameters cannot be met?
Would a "phasing in" of the new limits be appropriate? Yes No
If yes, please provide a schedule (and basis for that schedule) with the regional
office recommendations:
If no, why not?
Special Instructions or Conditions
Wasteload sent to EPA? (Major) Al - p ton the l st to Send to- Pti 7 (Y or N)
(If yes, then attach schematic, toxics spreadsheet, copy of model, or, if not modeled, then old
assumptions that were made, and description of how it fits into basinwide plan)
Additional Information attached? r (Y or N) If yes, explain with attachments.
1 oxi'- S?read 5hee+
L,014 ni4e5

C.O. IA -It -rev t LL£
Facility Name WHIT MA-2St-J LA) w7 P
Permit # (NCO° 21920 Pipe # BDI
CHRONIC TOXICITY PASS/FAIL PERMIT LIMIT (QRTRLY)
The effluent discharge shall at no time exhibit chronic toxicity using test procedures outlined in:
1.) The North Carolina Ceriodaphnia chronic effluent bioassay procedure (North Carolina Chronic Bioassay
Procedure - Revised *September 1989) or subsequent versions.
The effluent concentration at which there may be no observable inhibition of reproduction or significant mortality
is 4S % (defined as treatment two in the North Carolina procedure document). The permit holder shall perform
quarterbv monitoring using this procedure to establish compliance with the permit condition. The first test will be
performed after thirty days from the effective date of this permit during the months of
0cr, 3-Am, APQ ,jut_ . Effluent sampling for this testing shall be performed at the NPDES
permitted final effluent discharge below all treatment processes.
All toxicity testing results required as part of this permit condition will be entered on the Effluent Discharge
Monitoring Form (MR-1) for the month in which it was performed, using the parameter code TGP3B.
Additionally, DEM Form AT-1 (original) is to be sent to the following address:
Attention: Environmental Sciences Branch
North Carolina Division of
Environmental Management
4401 Reedy Creek Road
Raleigh, N.C. 27607
Test data shall be complete and accurate and include all supporting chemical/physical measurements performed in
association with the toxicity tests, as well'as all dosefresponse data. Total residual chlorine of the effluent toxicity
sample must be measured and reported if chlorine is employed for disinfection of the waste stream.
Should any single quarterly monitoring indicate a failure to meet specified limits, then monthly monitoring will
begin immediately until such time that a single test is passed. Upon passing, this monthly test requirement will
revert to quarterly in the months specified above.
Should any test data from this monitoring requirement or tests performed by the North Carolina Division of
Environmental Management indicate potential impacts to the receiving stream, this permit may be re -opened and
modified to include alternate monitoring requirements or limits.
NOTE: Failure to achieve test conditions as specified in the cited document, such as minimum control organism
survival and appropriate environmental controls, shall constitute an invalid test and will require immediate
retesting(within 30 days of initial monitoring event). Failure to submit suitable test results will constitute
noncompliance with monitoring requirements.
7Q10 4.`7 cfs
Permitted Flow 2.5 MGD Recommended by:
IWC 4s . 1.1 %
Basin & Sub -basin (Y3o7 5S woa,... `--?f/. (,uL „
Receiving Stream bk),t, re NAi %d
County Co, 104 PL.S Date 1o/25/g1
QCL PIF Version 9/91

10/25/91 ver 3.1 T OXICS REVIEW
Facility: whiteville
NPDES Permit No.: nc0021920
Status (E, P, or M): e
Permitted Flow: 2.5 mgd
Actual Average Flow: 1.45 mgd
Subbasin: '030758
Receiving Stream: white marsh I PRETREATMENT DATA I----EFLLUENT DATA ----
Stream Classification: c-sw I ACTUAL PERMITTEDI
7Q10: 4.70 cfs I Ind. + Ind. + 1 FREQUENCY
IWC: 45.19 % I Domestic PERMITTED Domestic 1 OBSERVED of Chronic
Stn'd / Bkg 1 Removal Domestic Act.Ind. Total Industrial Total 1 Eflluent Criteria
Pollutant AL Conc. 1 Eff. Load Load Load Load Load 1 Conc. Violations
(ug/1) (ug/1) 1 % (#/d) (#/d) (#/d) (#/d) (#/d) 1 (ug/1) (#vio/#sam)
Cadmium S 2.0 1 92% 0.0100 0.0208 0.03 0.0421 0.052 1 I
Chromium S 50.0 1 76% 0.0300 0.0173 0.05 1.5162 1.546 1 I I
Copper AL 7.0 1 95% 0.1200 0.0310 0.15 1.8110 1.931 1 10.0 1 N
Nickel S 88.0 1 40% 0.1400 0.0512 0.19 2.3164 2.456 1 105.0 1 P
Lead S 25.0 1 81% 0.1200 0.0363 0.16 0.3791 0.499 1 1 U
Zinc AL 50.0 1 75% 0.5300 0.0772 0.61 1.3056 1.836 1 40.0 1 T
Cyanide S 5.0 1 59% 0.0300 0.0040 0.03 0.5896 0.620 1 I
Mercury S 0.012 1 86% 0.0020 0.0605 0.06 0.0042 0.006 1 1 S
Silver AL 0.06 1 94% 0.1200 0.0000 0.12 0.2106 0.331 1 1 E
riU01'lP5 S 1,800.00 1 8% 2.8 0.0 2.80 26.5 29.340 1 I C
Arsenic S 50.00 1 40% 0.0300 0.0 0.03 0.2106 0.241 1 1 T
Phenols S NA 1 99% I 0.0 1 I
NH3-N C 1 0% I 1 0
T.R.Chlor.AL 17.0 1 0% I 1 N
Pollutant
ALLOWABLE PRDCT'D PRDCT'D PRDCT'D MONITOR/LIMIT I--ADTN'L RECMMDTN'S--
0.0 Effluent Effluent Instream 1 Recomm'd
Conc. using using Conc. Based on Based on Based on 1 FREQUENCY INSTREAM
Allowable CHRONIC ACTUAL PERMIT using ACTUAL PERMITTED OBSERVED 1 Eff. Mon. Monitor.
Load Criteria Influent Influent OBSERVED Influent Influent Effluent 1 based on Recomm'd ?
(#/d) (ug/1) (ug/1) (ug/1) (ug/l) Loading Loading Data 1 OBSERVED (YES/NO)
Cadmium S 0.94 4.426 0.204 0.344 0.00 Monitor Monitor 1 1 A
Chromium S 7.80 110.645 0.938 30.668 0.00 Limit ! 1 1 N
Copper AL 5.24 15.490 0.624 7.979 4.52 Monitor Monitor Monitor 1 Monthly NO 1 A
Nickel S' 5.49 194.735 9.481 121.802 47.45 Monitor Limit Limit' 1 NCAC NO 1 L
Lead S 4.93 55.323 2.454 7.837 0.00 Monitor Limit 1 1 Y
Zinc AL 7.49 110.645 12.545 37.925 18.08 Monitor Monitor Monitor 1 Monthly NO 1 S
Cyanide S 0.46 11.065 1.152 20.994 0.00 Limit Limit 1 1 I
Mercury S 0.00 0.027 0.723 0.072 0.00 Limit Limit 1 1 S
Silver AL 0.04 0.133 0.595 1.639 0.00 Monitor Monitor 1 I
ttgviT 2-12e. 1 S 73.25 3983.226 212.888 2230.764 0.00 Monitor Limit 1 1 R
'Arsenic S 3.12 110.645 1.488 11.930 0.00 Monitor Limit I 1 E
Phenols S 0.000 0.000 0.000 0.00 I NCAC NO 1 S
NH3-N C 0.000 0.00 I I U
T.R.Chlor.AL 37.619 0.00 1 I L
I I T
I I S

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STREAM DATA
INSTREAM SELF -MONITORING DATA
MONTHLY AVERAGES
Discharger: NH 1TEV 1 LLE
Receiving Stream: kj b-tu M Atz' 4
Upstream Location: •Gts 74/7t,
DATE
Dec-91
Nov-91
Oct-91
Sp-91
Aug-91
Jul-.9i
Jun-91
May-91
Apr-91
Mar-91
Feb-91
Jan-91
Dec-90
Nov-90
Oct-90
Sep-90
Aug-90
Jul-90
Jun-90
May-90
Apr-90
Mar-9
Feb-9
Jan-9
Dec-8
Nov-8
Oct-8
Sep-8
Aug-8
Jul-8
Jun-8
May-8
Apr-8
Mar-8
Feb-8
Jan-8
TEMP
D.O.
COND.
Permit No. NC_O OZl 12O
Sub -basin:
Downstream Location: l Pia i / STL.L
FECAL COLT.
0
o�
0
9
9
9
9
9
9
9
9
9
9
9
9
27.I(24-.8)
Z
3.2(Z.)_
7o(Bto)
1
2* .2(2S.-
3. 4 (5. 0oc,(161)
l01 (g4)
,
25, (i7,)
2-3(1,q)
z3A-(26.2,
3so( Z,I J
,
113 (37.1
22.1(271)
3#4•(2,9)
'
6,1(84
19.6 (20,9)
¢. 8 (3 1)
6o (6,0
610 104)
13.669.
1.7(1.i)_
Hal (04.8)
8. o (6,5)
6l g4)
9, 603)
9 & ('S, 4)
% 62.6)v
1303 (OD)
53 C4. Aez(i
48,
12.3(/.$)
4.9(4,)
120 (34?
/0 4-(21,4
45(3,1)
271(ow)
2z(Z7,2)
2.4-6. 7)
2416,320
D.O. COND. FECAL CO
21.4(Z5.3)
3.1(2,l)
74(932)
23.1(26)
3.3(Z .9)
/4 (Z33)
25,6 (Z7
3.7l2-. z
I Z�4 4)
Z3 (24-,5
3,0(1, g)
la.c(3�)
22.5(26.71
, 6 (3 , I
3s (7Z
11�3(j9,7)
4.7(3,5
57(68
1.0(6,4)
g��/S9
,/3(18.7)
fn,9(14,3)
76((�.4)
9z6od
6.9(//. 6)
7,1(5)
f 37(Sl o)
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5;4(3..)
7i6,e
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/33(
/ 1.(z/. 5)1
44(2,6)
(8 7(439,
21.1(4.8,
3,1(/, 9)
18 5-64vo�
Page 1

DIVISION OF ENVIRONMENTAL MANAGEMENT
October 7, 1991
MEMORANDUM
To: Don Safrit
Permits and& ngi eering Unit
From: Dave Adkins
Subject: City of Whiteville
NPDES Permit No. NC002
Columbus County
It has come to the attention of this Office that the City
of Whiteville is accepting wastewater from a groundwater
remediation site which may not be receiving optimum treatment.
With this in mind it is recommended that any draft permit for the
City of Whiteville include the following quarterly monitoring
requirements: toluene, benzene, total xylene, and ethyl benzene.
If you have any questions, please.
DA002.00T
CC:
Steve Long
Wilmington Regional Files
Central Files
IZr - SPoK-tit (209L NE B fi3owr . 50c sit)cc, -54 E TocvJ)
E(Ar) t 59 (& 1`j poz 2aiwc--M-- (404t (7 S CSTR��114�1)r, l 7 ToTA —
Pt•RrtsriO
(-cow FP-oM !/� ©3 e r5 t411.5 l.ov) ✓� 30, ®OO 4 pD ( 2,5 hkct i Fro �1 Fo fz
WN 11.641t,t,rd -rWJ R-i OA. T5 wW ,IJar » c6scpt2Y • !ot,A Y I t, E
Co, p u.N s (WV P pe• b ASeXrlON - S Ito u 1,3) Nor 13,0
A fO1 L M S-- avveViA-fioii r5 ►Jor ADEQ(.kre
514out,t7 ENFo2LE pa_itermr cutt(T5 -fit a iCi
w�l�-n:v►1-4-E

d-5o75.5
fJpnP.2sw1
State of North Carolina
Department of Environment, Health, and Natural Resources
Wilmington Regional Office
James G. Martin, Governor Bob Jamieson
William W. Cobey, Jr., Secretary Regional Manager
April 3, 1991
DIVISION OF ENVIRONMENTAL MANAGEMENT
Mr. Howard Jones, City Manager
City of Whiteville
Post Office Box 607
Whiteville, North Carolina 28472
Dear Mr. Jones:
Subject: NPDES Compliance Inspection Report
City of Whiteville
Permit No. NC0021920
Columbus County
03o7 a WrI(7E- I t - 14
Please find attached a copy of the completed form entitled
"NPDES Compliance Inspection Report". The report summarizes the
findings of a recent inspection which was conducted on April 2,
1991 to determine compliance with permit requirements.
Your attention is directed towards a summary of findings and
comments noted during the inspection and listed in Section "D" of
the subject report.
If you have any questions concerning this report, please
contact me at the Wilmington Regional Office, telephone number
[phone].
Sincerely,
Pat C. Durrett
Wastewater Treatment Plant Consultant
PCD:NC21920.APR + i
Enclosure
cc: Dan Ahern, EPA RECEIVED
Steve Long
Wilmington Regional Office APR - 4 1991
Central Files
Technical Support Branch TECHNICAL SUPPORT BRANCH
Kent Wiggins
1
7225 Wrightsville Avenue, Wilmington, N.C. 28403-3696 • Telephone [phone] • Fax [phone]

NPDES COMPLIANCE INSPECTION
Section A: National Data System Coding
Transaction Code: N NPDES No. NC0021920
Date: 4/2/91 Inspection Type: C
Facility Type: 1
BI: N QA: N
Section B: Facility Data
Name and Location of Facility Inspected:
City of Whiteville, North Carolina
Entry Time: 9:15am Exit Time/Date:
REPORT
Inspector: S
Facility Evaluating Rating: 1
11:O0am 4/2/91
Permit Effective Date: 4/1/87 Permit Expiration Date:
Name (s) , Title (s) of On -Site Representative (s) :
Mike Hammond, Temporary ORC
Faye Moore, Lab Technician
Phone Number: [phone]
Name, Title and Address of Responsible Official:
Mr. Howard Jones, City Manager
City of Whiteville
P. O. Box 607
Whiteville, North Carolina 28472
3/31/92
Phone Number: 919/642-8046 Contacted: No
Section C: Areas Evaluated During Inspection
(S=Satisfactory, M=Marginal, U=Unsatisfactory, N=Not Evaluated)
Permit: S
Facility Site Review: N
Laboratory: S
Pretreatment: S
Self -Monitoring Program: S
Sludge Disposal: S
Compliance Status: Compliance
Records/Reports: S
Flow Measurement: S
Effluent/Receiving Waters: S
Compliance Schedules: N
Operations & Maintenance: U
(see comments under Section D)
No. 2

City of Whiteville
Page Two
Section D: Summary of Findings/Comments
1. A review of the self -monitoring data submitted by the
facility for the past twelve months shows the facility to
be in compliance with the limits contained in your NPDES
permit.
2. Visual observations made during the inspection show that
routine operation and maintenance is not being performed as
needed. There are no in -plant process control tests being
done so that operational changes can be made to enhance plant
performance. The clarifier weirs were loaded with solids and
heavy accumulations of algae. The flow box at the end of the
polishing pond was also over -run with algae which can affect
the downstream process units and the quality of your
effluent.
3. You must control the amount of solids leaving your clarifiers
and going to your pond or you will create the same type of
problems that you have encountered in the past.
4. The effluent contained light amounts of suspended matter.
Name and Signature of Inspector:
Pat C. Durrett
Agency/Office/Telephone: DEHNR/Wilmington/[phone]
Date: 4/2/91

WASTEWATER TREATMENT PLANT STUDY
FOR THE CITY OF WHITEVILLE
Black & Veatch Engineers -Architects
110 West Walker Avenue
Asheboro, North Carolina
June 1990
AUG 16 6c:
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I HEREBY CERTIFY THAT THIS REPORT WAS PREPARED BY ME OR
UNDER MY DIRECT SUPERVISION THIS /91AY OF JUKE 1990.
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o ph E. Hardee, P.E.
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CITY OF WHITEVILLE
WASTEWATER TREATMENT PLANT STUDY
I. INTRODUCTION
II. SUMMARY
III. HISTORY OF THE EXISTING PLANT
IV. PROCESS UNIT DESCRIPTIONS
V. INVESTIGATIONS AND ALTERNATIVES
VI. FINANCING •
AUG 16 1993
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I. f NTRODUCTION
The City of Whiteville authorized Black & Veatch in March 1990 to conduct a
study of the wastewater treatment plant. The purpose of this study is to analyze
the performance of the plant and to recommend improvements which will increase
the reliability, flexibility, and efficiency of the treatment system.
The City will be able to use this information to ensure that adequate sanitary
services will be provided to its citizens. Cost opinions are offered to allow
budgetary planning and the selection of alternatives that will give the best value.
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II. SUMMARY
The wastewater treatment plant for the City of Whiteville has been in
operation for 18 years. Although the plant is currently meeting its permitted
limits, there are several major items of equipment in need of repair or
replacement, and several modifications which should be made to improve the
plant's performance and efficiency. These are as follows:
1. The screw lift pumps should be rehabilitated and put back into service as the
main influent pumps. A bypass line at the influent pump wet well should be
installed to permit better maintenance of the influent pumps. The probable cost
is $90,000.
2. At the top of the influent pump structure, a mechanical bar screen with
3/8-inch openings is needed to separate and remove trash and indigestible solids.
A grit basin following the bar screen would be desirable, but is not cost-effective
at this time. The probable cost is $94,000.
3. The plant can provide adequate treatment using only one of the two existing
aeration basins. The second basin should be converted to a stormwater holding
basin. A small pumping station would be built to transfer water from the holding
basin to the treatment basin. This will equalize flows so that the plant can
provide a consistent level of treatment during peak flow periods.
The brush -rotor aerators are worn and corroded. They should be replaced
with new rotors. In order to provide better control and more efficiency, the single
100-hp drive motor should be replaced by dual 50-hp motors with adjustable
speed controls. Additional aeration should be supplied by floating aerators. Only
the basin which is designated for treatment will require aeration modifications.
The existing equipment should be retained in the basin to be used for stormwater
holding.
The effluent structures in the aeration basins should be modified to permit the
treatment basin to use both existing clarifiers. New buried pipe will be required
to accomplish this, whether by pumping or by gravity. Also, the gunite walls of
the aeration basins need to be repaired. The probable cost is $400,000.
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4. The control building should be expanded to provide adequate laboratory and
office space. This may be done most simply by constructing a new addition to the
existing building. The probable cost is $65,000. Other options include relocating
the chlorine disinfection system, or replacing it with an ultra -violet disinfection
system, and using the existing room for office/laboratory space.
A decision to convert to UV would require consideration of future toxicity
limits on the discharge permit, and a comparison of operating costs with the
existing chlorine system.
5. A non -potable water system could potentially save the City of Whiteville
money by using the treatment plant effluent for the chlorine solution and for
washing down equipment. Currently, the plant uses potable water from the
distribution system for these purposes. Probable cost is $95,000.
6. The 50-hp aerator in the re -aeration basin should be replaced with a 20-hp
unit. The smaller aerator would provide annual power savings of about $11,000.
Probable cost is $16,000.
7. The feasibility of installing standby power generators at the wastewater
treatment plant and at Pump Station 1 was studied. These generators are needed
to provide reliable and continuous service. Generator sizes were determined
according to anticipated loads. The probable cost is $150,000.
8. In addition to the work at the wastewater treatment plant, a third pump at
Pump Station 1 is needed to provide firm capacity in case one of the two existing
pumps is out of service. Probable cost is $65,000.
9. The City is still experiencing infiltration -inflow problems. These need to be
addressed. A reasonable budget amount for this is $100,000.
It is also recommended that the City provide a system that will send a signal
to the Public Safety Building in the event of a power failure or other outage at the
wastewater treatment plant. If this can be accomplished, the wastewater
treatment plant staff can probably be reduced by one to two people, while
providing 8-hour, 7-day per week staffing.
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The following tabulation provides a recommended priority to the needed
improvements that have been identified.
Order of
Priority Description . Probable Cost
Reaeration Aerator la 000
Aeration Basin - Clarifier 400,000
Modifications & Concrete Re-hab
Sewer Line Re-hab 100,000
Influent Pumping Modifications 90,000
Office/Laboratory Expansion 65,000
Mechanical Bar Screen 94,000
f 7. Additional Pump at Pump 65,000
Station 1
g 8. Standby Power Generation 150,000
Equipment
9. Non -potable Water System 95,000
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III. HISTORY OF THE EXISTING PLANT
The existing wastewater treatment plant for the City of Whiteville was
designed in 1971 by Moore, Gardner & Associates. It replaced the old plant
located off of Mill Street that had been in operation since the early 1940s. The
new plant was constructed in 1972-73 by Brown Construction Company for a cost
of approximately $1,200,000. The project was financed by USEPA and Water
Pollution Control Federation .(WPCF) grants combined with local monies.
The original plant capacity was 2.5 million gallons per day (mgd) and was
designed to receive wastewater anticipated from a large dyeing and finishing
industry in addition to the City's flow. This industry never located in Whiteville,
and actual required capacity has remained between 1.0 to 1.5 mgd. The plant
provides 48 hours of aeration at the 2.5 mgd rate, and has performed very well
over the past 18 years.
Major capital expenditures since the plant was constructed include
approximately $400,000 in 1984 for a new influent pump station, and $200,000 in
1988 for the conversion of the sludge drying beds to thickening/holding basins.
Three chief operators have maintained and operated the plant since it began
service. It is now in the charge of Mr. Asure Spivey, who has done an excellent
job since September 1987.
The Whiteville wastewater plant is simple in concept and operation. The raw
sewage is lifted by pumps to an elevation where it flows by gravity through the rest
of the plant. Two large basins provide the oxygen and detention time necessary
for bacteria and microorganisms to consume the organic material in the sewage.
This biological process is referred to as "activated sludge."
Weir structures in each basin draw off liquid to the clarifier basins, where
most of the solids settle out. The clarified water flows to the fine solids settling
pond and the settled solids, which consist primarily of bacteria and other
organisms, are returned to the activated sludge basins. The fine solids pond has a
volume of 6 million gallons, and provides an average of 4 days' detention time
during normal dry -weather flow conditions. The quiescent conditions in the pond
permit the finer and less dense particles to settle out.
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From the fine solids settling pond, the clarified water passes through a re -
aeration basin where the dissolved oxygen is replenished. The final step is to flow
through a chlorine contact chamber where the treated water is disinfected before
it is discharged to the White Marsh Swamp.
The effluent quality limits for the Whiteville plant are 10 milligrams per liter
(mg/1) total suspended solids (TSS), 5 mg/1 biological oxygen demand (BOD5), and
2 mg/1 ammonia. These are among the most stringent limits imposed in the state
of North Carolina. Effluent from the Whiteville wastewater treatment plant is
actually cleaner and contains more oxygen than the receiving waters to which it is
discharged.
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IV. PROCESS UNIT DESCRIPTIONS
A. Influent Pumping Station
The original influent pumps consisted of twin 54-inch diameter screw lift
pumps. The pumps are rated at 6,000 gallons per minute (gpm) each and were
manufactured by Zimpro-Passavant in 1972. Incoming sewage from two 30-inch
lines flows into a wet well at the bottom of the screws. From there it is lifted to
the head works at the top of the screw lift pump structure.
In 1984, the City constructed a new influent pump station with two Gorinan-
Rupp pumps. The Gorman -Rupp pumps are self -priming centrifugal pumps rated
at 3,050 gpm each. They are installed in a concrete structure directly upstream
from the original screw lift pumps, and also lift the wastewater from the screw lift
pump wet well. Since they were put into service, the Gorman -Rupp pumps have
served as the main influent pumps, with the screw lift pumps being used for
backup during heavy flows. Only one of the screw lift pumps is operational at this
time.
B. Preliminary Treatment
Preliminary treatment consists of a bar screen and a comminutor that follow
the screw lift pump structure. Incoming flows may pass through either the bar
screen or the comminutor, but not through both. The function of the bar screen
is to trap and separate larger objects, such as sticks and rags, from the wastewater.
The comminutor is meant to grind or tear materials into smaller pieces. It is now
rarely, if ever, used in the operation of the plant.
The problem with both of these methods is that they do not prevent the bulk
of indigestible materials, such as plastics, glass, and metals, from entering the
treatment basins. The bar screen openings, at 1 and 1/8-inches, are too large to
effectively stop anything but the coarsest items of trash. The comminutor can
grind, but it does not remove anything.
Once these non -degradable materials pass through the headworks, there is no
method of removing them from the treatment system. They accumulate in the
plant piping and basins, and clog the weirs. Over a long period of time, they
reduce the capacity and degrade the performance of the plant.
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i

C. Aeration Basins
The aeration basins are the primary treatment units of the wastewater plant.
Each concrete lined basin contains 2.5 million gallons with a water depth of
12 feet. Sewage flows by gravity to a splitter box Iocated between the basins.
There the flow is divided between the two basins. It is the purpose of the basins
to support a healthy and active population of micro-organisms which consume the
organic wastes. The speed and level of treatment depends on the metabolic rates
of the organisms, which in turn depend on the temperature and amount of oxygen
in the liquid.
Oxygen is supplied to the system by airbrush rotors. Each basin has four
rotors, 22 feet long. A 100-hp motor in the center drives all four rotors. The
operator has access to the motor, gear boxes, and rotor couplings by means of a
catwalk bridge across the basin. In addition to splashing and mixing with air, the
rotors keep the water moving in a circular pattern around the basin.
The rotor assemblies were manufactured by Zimpro-Passavant and installed in
1972. The rotors were fabricated from mild steel and, when new, coated with a
standard shop paint. They have served 18 years in harsh conditions with no other
corrosion protection. They are badly corroded and several of the brush tips have
fallen off.
The gear boxes and couplings are worn and are difficult to disengage and
lubricate. The motor horsepower is excessive for normal daily operations. In fact,
the operator usually runs only two rotors at a time in each basin.
The basins themselves have operated for 18 years without being drained and
cleaned and with no system for removing grit, glass, sand, or other non -degradable
materials. In all probability, they have accumulated a significant layer of sediment
which decreases their capacity. Additionally the concrete lining needs to be
rehabilitated to prevent possible leakage.
D. Clarifiers
Liquid from each aeration basin flows through a weir structure to a clarifier.
The clarifiers are circular concrete tanks 65 feet in diameter with water depths of
8 feet. Each clarifier is designed to handle a flow of 1.25 mgd (one half the daily
plant capacity). The average liquid detention time in the clarifiers is about four
hours.
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The solids in the treated effluent from the aeration basins settle to the bottom
of each clarifier. Slowly -rotating rake arms scrape the sludge to a central
collection pit. From there, the sludge is recirculated to the head of the plant and
excess sludge is periodically "wasted" to the sludge thickening beds. These excess
sludge solids are hauled away and disposed of as a fertilizer and soil conditioner
on agricultural areas that produce non -human consumption crops.
Floating scum is skimmed off the surface of the clarifiers and returned with
the sludge to the head of the plant. The clarified water flows under a baffle and
over a weir located at the outer circumference of the clarifiers. It flows by gravity
to a junction box, where the effluent from both clarifiers combines and flows to
the fine solids settling pond.
Each clarifier is dedicated to one aeration basin. The existing piping will not
permit the use of both clarifiers with a single aeration basin. The structures and
equipment are in reasonably good condition, but because of this piping restriction,
the clarifiers represent a serious bottleneck in the treatment process.
E. Fine Solids Settling Pond
The fine solids settling pond (also called' the retention basin) is a rectangular
clay -lined pond measuring approximately 434 feet by 204 feet. With a surface
area of almost 2 acres and an average water depth of 11.5 feet, the pond contains
6 million gallons of water. This volume provides a detention time of 1.5 to 4 days,
depending on the rate of flow through the plant.
The function of the pond is to provide quiet conditions for an extended period
of time so that fine solids can settle out. A beneficial side effect is the additional
treatment due to natural biological activity.
The pond has been recently cleaned out and is in good condition.
F. Re -aeration Basin
The re -aeration basin is a concrete -lined basin measuring 89 ft square. The
water depth is maintained at 10 ft for a volume of 400,000 gallons. Effluent from
the settling pond enters the re -aeration basin through an intake structure at the
bottom of one corner. A floating surface aerator powered by a 50-hp motor raises
the dissolved oxygen content of the treated wastewater before it is disinfected and
discharged.
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The basin is structurally sound and the aerator performs adequately. The
motor, however, is larger than it needs to be and contributes to the excessive
energy costs for operating this plant.
()ChIorine Contact Chamber
The chlorine contact chamber is a series of concrete baffles and channels. A
strong solution of chlorine is injected into the water as it enters the chamber. The
water slowly winds around the baffles and along the channels as the chlorine
diffuses evenly and kills bacteria. At the design flow of 2.5 mgd, the contact
chamber provides a detention time of 30 minutes.
Chlorine is provided in 1-ton cylinders. Fischer & Porter chlorinators mix the
gas with water and allow the operator to control the strength of the solution.
Results from bacteriological tests indicate that the current disinfection methods
are reducing the number of living bacteria to' less than one tenth of the level in
the receiving waters.
The chlorine system is working as it was designed to, but there are a few
problems associated with chlorine disinfection. The primary one is safety.
Chlorine gas is toxic and requires special care in handling.
The residual chlorine discharged to the swamp is mildly toxic to some species
of fish and other natural life in the swamp. It is likely that the State will establish
more rigid effluent toxicity limits in the next few years.
A third detriment is that the system uses potable water to make up the
chlorine solution. The amount of water used could be sold to billable customers
for close to $1000 per month. This, plus the cost of chlorine, contributes
approximately $15,000 per year to the annual operating costs of the plant.
H. Sewer Line Rehabilitation
The City continues to experience infiltration inflow problems. The cost of
removing this extraneous water from the wastewater collection system will be
some of the most cost effective dollars spent. An amount of $100,000 has been
included in the budgeted improvements for this item.
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V. INVESTIGATIONS AND ALTERNATIVES
A. Influent Pumps
The screw lift pumps are valuable items of equipment that should be
rehabilitated and used as the primary influent pumps. Each screw Iift by itself can
handle the rated capacity of both Gorman -Rupp centrifugal pumps. They are
more efficient because they turn constantly and their power requirements are
directly proportional to the amount of water being pumped. The centrifugal
pumps start and stop frequently based on float controls which respond to the wet
well level. Each start requires a power surge several times higher than the full
load current. This method of operation also tends to upset the treatment process
by delivering raw sewage to the aeration basins in intermittent slugs. The screw
lift pumps deliver the sewage at the rate it comes in, continuously and smoothly.
Another virtue of the screw lift pumps is that screening and degritting are not
required to protect them. The grit in the wastewater has already worn out one set
of impellers in the centrifugal pumps at a cost of more than $2,000.
1. Alternative 1. The existing configuration of influent and suction piping
makes it difficult to provide maintenance for the screw lift pumps and is the
primary reason the centrifugal pumps were installed in 1984. The lower bearings,
which are submerged in the wet well, are in need of repair and/or replacement.
One of these bearings can be isolated for repair by using a clumsy arrangement of
plywood to wall off one side of the wet well, and pumping the leakage to the
other side. The second bearing is next to an influent entrance that cannot be
plugged or bypassed. In order to make this bearing more accessible, a short
bypass line should be constructed that will combine the flows from both influent
mains to a common entrance into the wet well.
The probable cost for the bypass line with two slide gates and a 30-inch tee is
$40,000.
2. Alternative 2. The motors for the screw lift pumps are both in sound
mechanical condition, but are badly in need of cleaning and repainting. The screw
bodies can be rehabilitated by blasting and painting when the bearings are
replaced. It may also be necessary to replace the automatic grease pumps and
rebuild the gear reducers. The cost of a total rehabilitation of the screw lift
pumps, with replacement of the upper and lower bearings, is estimated to be
$50,000.
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Note: According to the manufacturer, the bearings would probably only
require new journals and bronze bearings, and the grease pumps would probably
only need to be cleaned and adjusted. In this case, the above cost would be
reduced to $31,000.
B. New Mechanical Bar Screen and Grit Removal Facilities
The first step in a wastewater treatment process is to remove coarse objects
and sediment which may clog the system. The existing pretreatment facilities are
not adequate. A self-cleaning mechanical bar screen with smaller openings is
needed to prevent the passage of non -degradable materials which are always
present in modern domestic sewage. A degritting basin would help prevent
sedimentation in pipelines and basins. Both items would protect downstream
mechanical equipment from abrasion and clogging.
1. Alternative 1. The logical order for the treatment process would place
this equipment on the low ground ahead of everything else in the plant; first the
bar screen, then the grit basin, then the main influent pumps (Figure B-1).
Unfortunately, the depth of the 30-inch influent lines would require an excavation
14 feet deep. Due to the low elevation and high groundwater table, a concrete
structure would need to be heavily ballasted and reinforced.
The hydraulics of this arrangement would be very difficult, because the flows
from two influent mains would have to be combined before they pass through the
bar screen. Approximately 200 feet of 30-inch diameter pipe, laid with practically
no slope, would be required. No allowance for headloss through the equipment
could be provided without drastically altering the pump station wet well.
The cost of construction at this location would also be high because of the
necessity for sheeting and dewatering to remove water from the construction site.
The estimated cost for design and installation of a mechanical bar screen and grit
removal basin on the low site is $376,000.
2. Alternative 2. The mechanical bar screen could be installed in the
existing comminutor channel at the top of the screw lift pumps. This would save
the cost of building a new concrete structure. There is enough space to install a
degritting basin between the existing headworks and the first splitter box
(Figure B-2). Removing grit at this point would prevent the deposits of sediment
in the basins, but would not protect the centrifugal influent pumps from abrasion.
The screw lift pumps are relatively unaffected by grit.
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SCREW LIFT PUMPS
FILL FOR ACCESS ROAD
rn Es4±i�.:=
▪ fii':--I-a
• {,,�
cm t 1:: ' I
r
GRIT BASW C
MECHANICAL
BAR SCREEN
1

SCREW LIFT PUMPS
=0
=0
El
EXISTING MANUAL
BAR SCREEN
000
000
000
000
000
NEW MECHANICAL BAR SCREEN
WITH 3/8" OPENINGS
NEW GRIT BASIN
FIGURE B-2
EXISTING
SPLITTER
BOX

A degritting basin at this location would be difficult to build because of the
limited space and the presence of buried electrical cables. It would not, however,
require a deep excavation or dewatering. Estimated costs for this alternative are
$231,000.
3. Alternative 3. The third alternative is to install only the mechanical bar
screen in the existing comminutor channel. Given that the plant has operated for
18 years without a grit removal system, and that the centrifugal pumps would not
be protected by an installation at the top of the lift pump station, it may not be
cost effective to build a degritting facility at this time. If the aeration basins are
cleaned out during the proposed construction, it will be possible to develop a
better estimate of the amount of grit which is passing into the treatment works. A
grit removal system could be added in the future if necessary.
The cost for a mechanical bar screen in the existing channel is estimated at
$94,000.
Based upon our study of these alternatives it is our recommendation that the
grit removal system be delayed, and that the City install only the mechanical bar
screen in the existing channel.
C. Aeration Basin Modifications and Activated Sludge System
The existing aeration system consists of two large oval shaped basins, designed
to provide 48 hours of aeration at 2.5 mgd. Current daily flows average about
1.5 mgd, with peak flows that exceed 3 mgd during heavy rains.
Past operating experience has shown that it is not necessary to operate both
basins to meet treatment requirements. An improved usage of the excessive basin
volume available would be to use one of the basins as a holding tank to equalize
the high flows that occur during wet weather. Then, when influent rates return to
a normal range, the excess could be transferred to the second basin for treatment.
This mode of operation would eliminate the cost of aerating one of the basins and
would provide consistent flow rates to the aeration system and clarifiers even
during high flow periods.
The remaining treatment basin would need to be cleaned out. The brush
rotor aerators should be modified to provide better efficiency and greater control
of the aeration process.
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.r
4UG 18 1993
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If one basin is to operate at full capacity, extra clarification must be provided,
or else a method be devised that will allow both existing clarifiers to receive the
flow from a single aeration basin.
1. Alternative 1. The north basin would be converted to a flow equalization
holding tank. A weir in the existing splitter box would divert inflow to this basin
during high flow periods, while the treatment basin would receive flow at normal
rates. A new pump station would be provided to transfer water from the holding
tank to the treatment basin after the high flows recede.
The brush rotors in the south basin would be replaced by four new rotors.
They would be driven by two 50-hp motors with variable speed drives. Four
floating jet -type aerators would also be added to provide additional oxygen and
mixing as needed. This system would give the operator greater flexibility to
efficiently meet oxygen and mixing requirements.
Extra clarification would be provided by- installing an intra-channel clarifier
such as the "BOAT" by United Industries (Figure C-1). The existing clarifier for
the north basin could be used for additional sludge storage.
This alternative would significantly reduce power requirements, double the
clarifier capacity, and provide a three -step sludge thickening process. The
estimated cost is $935,000.
2. Alternative 2. This alternative is the same as Alternative 1 except that
the intra-channel clarifier would not be provided and the transfer pumps proposed
in Alternative 1 would also deliver flow from the treatment basin to one of the
existing clarifiers.
This would result in continuing with the existing clarifier capacity, somewhat
higher power requirements due to pumping, and no additional sludge thickening.
The estimated capital cost would be considerably lower at $320,000, plus $80,000
to clean and repair the aeration basin walls.
3. Alternative 3. It appears possible to modify the aeration basin effluent
structures so that water from the treatment basin would flow by gravity to both
existing clarifiers. The new piping would connect new concrete junction boxes
built on the sides of the existing weir structures at each aeration basin
(Figure C-2). Flow to the opposite clarifier would be accomplished by adjusting
the rotating weirs in the effluent structures.
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FILES

)I(
MODIFY HOLDING BASIN
SPLITTER
BOX
BOAT
CLARIFIER
NEW ► O
I - AERATORS
FINE SOLIDS
SETTLING
POND
TRANSFER
PUMPS
1 s
CONVERT
TO SLUDGE
STORAGE
FIGURE C-1

FIGURE C-2
EXISTING WEIR
STRUCTURE
CLARIFIER 1
NEW 12" LINE
CONTROL
BUILDING
CLARIFIER 2
\i„
NEW CONCRETE
JUNCTION BOXES

This alternative would eliminate the higher pumping costs of Alternative 2.
However, a pumping station would still be necessary to transfer the stormwater.
The capital cost would be approximately the same as Alternative 2.
We recommend that Alternatives 2 and 3 be investigated thoroughly during
the design phase to determine the more economical choice.
D. Laboratory Expansion and Control Building Renovation
The Iaboratory and office for the wastewater treatment plant are combined in
a room that has 225 square feet of floor area. Electrical panels, desks, tables,
laboratory counters and equipment take up close to 90 square feet of the available
area, leaving only 135 square feet for chairs and foot traffic. This is not adequate
space to allow freedom of movement, access to exits, and storage of historical
records by the operators and lab technician.
1. Alternative 1. The first alternative for expanding the lab/office area
would be to add space by extending the building to the south. The plan shown in
Figure D-1 would add 320 square feet to the existing floor area. Some of the
laboratory equipment, such as the fume hood and autoclave, would be replaced.
Safety items, such as an eyewash and shower, would be added. With counters and
cabinets, HVAC, electrical, and plumbing additions included, the estimated cost is
$65,000.
This expansion could be reduced to a range of smaller areas. For each square
foot of area removed, the probable cost will decrease by $75. However, an
additional 320 square feet, together with the existing area, would provide office/lab
space that is considered to be adequate for a 2.5 mgd plant.
2. Alternative 2. The existing cylinder storage and chlorine feed room is 193
square feet in area. This could be converted to lab/office space by moving the 1-
ton cylinder scales and feed -header assemblies outside. There is more than
adequate space on the existing outside platform to mount the feed assemblies,
with extra room for two or three reserve cylinders. It would need only a light roof
for shelter from direct sun and rain, and a short section of masonry wall to mount
gages and feed plumbing.
The converted area would require additional HVAC, a drop ceiling, new floor
surface, lighting, and furniture. The probable cost is estimated to be $52,000.
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0
rrp, .11;
eziay
CONTROL BUILDING MODIFICATIONS
ALTERNATIVE
4
ALTERNATIVE
20R3
EXISTING
LABORATORY
& OFFICE
ALTERNATIVE
• 1
FIGURE D-1

3. Alternative 3. A third alternative would be to abandon the chlorine
system entirely, replace it with an ultra -violet disinfection system, and convert the
chlorine cylinder storage room and the chlorinator room to office and lab space.
This would provide 237 square feet of additional area.
Ultra -violet systems disinfect wastewater through the use of radiation
produced by UV lights. These systems require more electrical power; however,
the storage and feed equipment as well as chemical costs required for chlorine can
be eliminated. Chlorine is also thought to be a significant contributor to
wastewater toxicity which is receiving a great deal of attention from NCDEM. On
the other hand, UV is completely free of toxicity.
The capital cost of a ultra -violet system would be approximately $72,000. This
would be offset by lower operating costs, increased safety, and the probable
reduction of toxicity in the discharge to White Swamp.
With the improvements to the converted building space, the total probable
cost for this alternative is $118,000.
4. Alternative 4. If the chlorine system is abandoned, as described in
Alternative 3, the concrete pad for storing 1-ton cylinders would be available for
other uses. The area could be enclosed with a simple metal or panel structure
and used for storage, or it could be bricked in and made a part of the laboratory
expansion. This would add another 240 square feet to the floor area. The
probable cost, including the ultra -violet system, is $147,000.
Based on the least cost per square -foot of additional area, we recommend
Alternative 1.
E. Non -potable Water System
The plant now uses potable water for all its water needs, including make-up
water for the chlorinators, and general plant wash -down requirements. The plant
operator estimates that more than 750,000 gallons are used each month.
Treated effluent could be drawn from the chlorine contact chamber and used
for these purposes by installing a non -potable water system. The system would be
kept completely separate from the potable water plumbing. It would consist of
pumps, a hydro -pneumatic tank, two or three yard hydrants, and buried piping to
the hydrants and chlorinator cabinets.
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The estimated cost for design and installation of a non -potable water system is
about $95,000. This cost would be offset by the annual operating expense of using
potable water, which could otherwise be sold to billable customers for
approximately $13,400 per year.
F. Reaeration
As indicated earlier, the 50-hp aerator in the reaeration basin is larger than
necessary; a 20-hp unit would be adequate. The power savings, assuming full time
operation, would be about $12,000/year with a 20-hp unit while the initial cost
would be about $16,000.
This replacement is strongly recommended.
G. Standby Power Generators
Black & Veatch has studied the need for emergency power generators at the
City of Whiteville wastewater treatment plant and Pumping Station 1. The
evaluation included the determination of existing loads, previous power outage
history for each site, and preliminary cost estimates for on -site emergency
generation.
The primary advantage to the City of Whiteville from installation of
emergency power generation at the wastewater treatment plant and Pump
Station 1 is the capability of continued system operation in case of utility power
service outages at these sites. Emergency power generation units can be installed
with automatic transfer switching for automatic start of the generation unit and
automatic switching of the electrical system to the generation unit.
The utility serving the City of Whiteville Pump Station 1 has reported a total
of 10 power interruptions in the previous five-year period, 1985-1989. These
interruptions ranged from 18 minutes to 3 hours with an average outage duration
of 39 minutes. The utility also reported additional outages from major storms
which were not documented. The utility did not have similar power outage history
for the wastewater treatment plant. However, the operations staff reported a
nominal two to three outages per year, and a similar outage history to Pump
Station 1 can be assumed for the wastewater treatment plant.
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di. L. ,...4, 474
4 0 , 6 �9
43
CENT�LPILES

}
In any justification of need
balance theydirect mat for emergency power generation,thematerialthe the City must
savings realized from co 1e emergency generation
savings are not simply monetary, continued power availability.
sewer lines r', as the City operating staff 11ty' The
may back up into residences and bu • has reported that
heavy storms. If these eventsbusinesses if the
can bepower fails during
providing reasonable service mayprevented, the responsible
emergency be sufficient justification for i approach to
g Y power generation. investing in on -site
Based on an analysis of exis • ite
and existing loadings at the
Pump
Station 1, a 400 kV and a 150 wastewater treatment
provide continued kV diesel generator are recommended plant
electric service duringnjmended to
recommends 1ncIudin Power outages.Black
g sufficient above- g clisite for 24
hours of continuous ground fuel storage at each
storm/disaster events generation capability, which should 1 24
to the utility power se Provide for unusual
described above service. Based upon thegenerator
fuel storage requirements wi sizes
between each generator � and automatic transfer
between a are as follows: and the utility switches
ty service, installed costs including
Iuding
Site
Pump Station 1
Wastewater Treatmen $ 50,000
t Plant $100,000
Annual costs for maintenance
future years because .enter , testing, and diesel refueling will be incurred o
operation and service, • operated periodically to
one hour each week of theyear Using an estimated exercise
non -emergency and a diesel fuel cost ofise time aof
l
g y operating costs for these units$1.30 per gallon, a
are as follows: annual
Average Fuel
Diesel Unit Consum do
n Annual O eratin
(gal/hr) (F) (52 hr x Costs
400 kV 29 ( gal/hr x $1.30
150 kW$1,960.40
10
$ 676.00
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H. Pump Station No. 1
Approximately two thirds of the wastewater influent is pumped through Pump
Station 1 at the old treatment plant site. During wet weather, both of the existing
pumps at that station are required to operate to keep up with the heavy flows. A
third pump should be installed to provide firm capacity in case one of the pumps
breaks down or is out of service for some reason. The electrical service will need
to be upgraded and the building expanded to accommodate the extra pump. The
estimated cost for adding a third pump at Pump Station 1 is $65,000.
1. Sewer Line Rehabilitation
The city staff should attempt to isolate the greatest problem areas with
respect to infiltration -inflow (I/I) prior to initiating any construction on the existing
lines. This will help to maximize the return on dollars spent. In other words,
remove the maximum amount of I/I per dollar expended.
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VI. Financing
The total probable cost of wastewater treatment plant improvements is
$1,075,000, based on 1990 dollars. The City of Whiteville's capital reserve fund
for water and sewer improvements now totals $551,828. One half of this is
available for improvements at the wastewater treatment plant. With total
improvements costing $1,075,000 in today's dollars, and $275,000 currently
available, $800,000 will need to be generated to accomplish all of the proposed
improvements. These improvements have been prioritized on the basis of need
and operational cost savings. The order of priority is as follows:
Order of
Priority Description Probable Cost
1. Reaeration Aerator $ 46040 2 ooa In h 0"
42! Aeration Basin - Clarifier 400,000 3 T¢ g2¢ c° 8 id
Modifications
/3. Infiltration Re-hab 100,000
Influent Pumping Modifications 90 000 -5 0 Pd Sic(
P g � l-
(.-5!. Office/Laboratory Expansion GUM - We'° 818
tra! Mechanical Bar Screen 94,000 4-064 '614
1
< 7. Additional Pump at Pump 65,000
Station 1
78. Standby Power Generation $ 150,000
Equipment
)C 9. Non -potable Water System 95,000
Total $1,075,000
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The sources of revenue for capital improvements are the one-half cent sales
tax and user charges. The one-half cent sales tax generates $40,000 per year for
wastewater. Additionally, any excess revenus from operation of the wastewater
system would be applicable to this project.
In order to generate revenues for the needed capital improvements, it will be
necessary to adjust the fees and charges for sewer service. This is a requirement
even if the funds are borrowed through issuance of G. 4. Bonds, since the rates
would have to be increased to cover the added debt service cost to the City.
•
;may'`ZPIr
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