NC0047597_Plan of Action_19900731

pp
ENGINEERING PROPOSAL
CITY OF DURHAM
FARRINGTON ROAD WWTP
pm
INTRODUCTION
pp
NPDES permit to discharge wastewater into the surface waters of the State.
This proposal is being submitted to update the previous engineering proposal
"" dated January 31, 1989 to reflect changes in the recommended facilities for
expansion of the Farrington Road Plant to 20 mgd. These facilities are
pm currently under design. Items from the original proposal which have not
changed are not addressed in this proposal.
This engineering proposal has been prepared to comply with the N.C.
Administrative Code and associated guidance for a request for renewal of an
DESCRIPTION OF WASTEWATER
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The description of the origin, type and flow of waste which is proposed
to be discharged has not changed from the original proposal. Additional data
pp on wastewater flow projections is presented in the attached table.
pm DESCRIPTION OF PROPOSED TREATMENT WORKS
pp
arrangement of major components, is presented in Table 5-1 and shown on Figure
5-2, which are attached. A layout plan of the proposed treatment works is
p' presented on Figure 5-1.
pp
A description of the proposed treatment works, including type and
pp
pp r291/3414-3/071890 -1-

Wastewater Flow Projections
Farrington Road
Wastewater Treatment Plant
City of Durham
Farrington Road
WWTP
Current maximum month flow, mgd
Committed maximum month capacity, mgd'
Current uncommitted flow for existing
development in service area, mgd2
Total current capacity required, mgd
2.82
0.22
14.15
15 mgd Plant
Capacity available for growth, mgd 0.85
Years of growth accommodated, years
@ 1% growth/year 6
@ 2% growth/year 3
@ 3% growth/year 2
@ 4% growth/year 1 1/2
20 mgd Plant
Capacity available for growth, mgd 5.85
Years of growth accommodated, years
@ 1% growth/year 35
@ 2% growth/year 17
@ 3% growth/year 12
@ 4% growth/year 9
Footnotes:
'Includes City and County projects plus committed new development projects.
2Assumes 360 gallons/day per household or lot for areas with failing septic tanks.

TABLE 5-1
FARRINGTON ROAD WWTP
DESIGN DATA
20 MGD DESIGN CAPACITY
(Including Bardenpho System)
A) Design Conditions
Annual Average Flow, mgd 20
Maximum Month Flow, mgd 24 (24.48)*
Peak Hourly Flow, mgd 60
Maximum Month Influent Wastewater Characteristics:**
BOD5, mg/L 245
TSS, mg/L 367
TKN, mg/L 26.1
NH3-N, mg/L 15.8
Total Phosphorus, mg/L 5.5
Maximum Month Activated Sludge Influent Wastewater Characteristics:**
BOD5, mg/L
TSS, mg/L
TKN, mg/L
NH3-N, mg/L
Total Phosphorus, mg/L
* Value in parentheses includes recycle streams.
**
Including recycle streams.
184
198
24.8
15.8
5.5

TABLE 5-1 (Continued)
Influent Pumping Station
Influent Bar Screens
Number
Clear opening between bars,
Method of cleaning
Influent Pumps
Number
Capacity of each pump, mgd
Firm capacity, mgd
Bar Screens (Original Plant)
Number
Capacity of each screen, mgd
Clear opening between bars, in.
Method of cleaning
Grit Collectors
Number
Capacity of each unit, mgd
Type
in.
Method of influent flow measurement
Method of cleaning
Primary Settling Basins
Number
Dimensions of each basin
Length, ft.
Width, ft.
Average depth, ft.
Total surface area, ft.2
Surface overflow rate at design
flow, gpd/ft.2
Volume of each basin, mil. gal.
Total volume, mil. gal.
Detention time at design flow, hr.
Primary sludge production, lb./day
Annual average
Maximum month
Primary Sludge Pumps
Number
Capacity of each pump, gpm
Total dynamic head, ft.
Horsepower
2
3/4
Mechanical
4
20
60+
2
Approx. 15
3/4
Mechanical
4
Approx. 15
Horizontal flow,
velocity control
Parshall flume
Mechanical
4
98
40
10.5
15,680
1,275
0.31
1.23
1.5
23,000
34,500
4
125
35
10

Poi
AEI
TABLE 5-1 (Continued)
Anoxic Tanks
Number 2
Dimensions of each tank
Length, ft. 240
Width, ft. 30
Depth, ft. Approx. 15.22
Total volume, mil. gal. 1.64
Detention time at design flow, hr. 2.0
Mixing/Aeration Tanks
Number 10
Dimensions of each tank
Width, ft. 50
Depth, ft. 15
a) Anaerobic Zone
Length, ft. 10
Total volume, mil. gal. 0.56
Detention time at design
flow, hr. 0.7
b) 1st Anoxic Zone
Length, ft. 50
Total volume, mil. gal. 2.81
Detention time at design
flow, hr. 3.4
c) Aerobic Zone
Length, ft. 190
Total volume, mil. gal. 10.66
Detention time at design
flow, hr. 12.8
d) 2nd Anoxic Zone
Length, ft. 46
Total volume, mil. gal. 2.58
Detention time at design
flow, hr. 3.1
e) Reaeration Zone
Length, ft. 10
Total volume, mil. gal. 0.56
Detention time at design
flow, hr. 0.67
f) Total
Length, ft. 306
Total volume, mil. gal. 17.17
Detention time at design
flow, hr. 20.6

IMI
NW
PM
TABLE 5-1 (Continued)
Mixing/Aeration Systems
a) Mixing System
Type Jet nozzle
Number of header systems in each
aeration tank
Number of header systems, total
Number of nozzles per header -
Number of pumps, each tank
Capacity of each pump, mgd -
b) Aeration System
Type Fine bubble
diffused air,
dome -type
Number of diffusers - *
Engine -driven blowers
Number - *
Maximum capacity of each blower, cfm - *
Motor -driven blowers
Number - *
Capacity of each blower, cfm - *
Final Clarifiers and Clarifier/Flocculators
Number 6
Diameter of each clarifier, ft. 4 @ 80
Diameter of each clarifier/flocculator, ft. 2 @ 120
Total surface area, ft.2 42,730
Surface overflow rate, gpd/ft.2 470
Sidewall water depth, ft. 16
Total volume, mil. gal. 5.1
Detention time at design flow, hr. 6.1
Type of sludge removal system Suction -type
Return Activated Sludge Pump Stations
Number 2
Number of pumps (total) 8
Capacity of each pump, gpm 4 @ 2,250
4 @ 2,900
Total dynamic head, ft. 14
Horsepower 15
(Pumping capacity variable through operation of recirculation valves)
* Mixing/aeration systems will be determined during final design.

NMI
TABLE 5-1 (Continued)
Effluent Filters
Number
Type of filters
4
Dual -media, traveling
bridge, automatic
backwash
Dimensions of each filter
Length, ft. 111.67
Width, ft. 15
Total surface area, ft.2 6,700
Filtration rate at design flow, gpm/ft.2 2.1
Depth of anthracite, in. 8
Depth of sand, in. 8
Disinfection Facilities
Type
Post Aeration Facilities
Type of post aeration
Height of fall at outlet structure
of chlorine contact chamber, ft.
Primary Sludge Thickener
Ultraviolet
Free fall
8-10
Number 1
Dimensions
Diameter, ft. 50
Sidewall water depth, ft. 12
Type of thickener Gravity
Surface area, ft.2 1,960
Solids loading rate, lb./ft.2-day
(annual average) 11.7
Anaerobic Digesters (15 mgd capacity*)
Number 2
Dimensions of each digester
Diameter, ft. 70
Sidewall water depth, ft. 22.4
Volume of each digester, ft.3 97,840
Total volume, ft.s 195,680
Design maximum month sludge
production, lb./day 49,980
Detention time at design sludge
production, days (6% solids) 15
*Estimated capacity of facilities used for backup sludge disposal by land
application.
5-5

TABLE 5-1 (Continued)
Anaerobic Digesters (Continued)
mm Volatile solids loading, lb./ft.3-day
(75% V.S.) 0.19
Maximum month digested sludge production,
p.mlb./day (50% VSS destroyed) 31,240
Type of covers Floating
Recirculation pumps
Number 2
P' Capacity of each pump, gpm 410
Total dynamic head, ft. 34
Horsepower 7-1/2
m, Transfer pumps
Number 2
Capacity, gpm 1 @ 300
1 @ 200
MR Total dynamic head, ft. 40
Horsepower 1 @ 15
1 @ 10
Psi
Pil
Psi
Gas Holder
Number 1
Volume, ft.3 50,000
Gravity Belt Thickeners (for WAS)
Number 2
Belt width, meters 2
Sludge Storage Tanks (15 mgd capacity*)
Number 2
Dimensions of each tank
Length, ft. 70.5
Width, ft. 55
Depth, ft. 16
Volume of each tank, ft.3 62,040
Total volume, ft.3 124,080
Annual average digested sludge production,
lb./day 20,390
Detention time at annual average digested
sludge production, days (4.0% solids) 15
Aeration system
Diffuser type and pattern Coarse bubble, cross roll
Number of diffusers 280
Design air requirement, scfm 4,340
*Estimated capacity of facilities used for backup sludge disposal by land
application.
5-6

RIR
PM
PM
PRI
TABLE 5-1 (Continued)
Sludge Storage Tanks (Continued)
Sludge Storage Tank Pump Station
Number of pumps 3
Capacity of each pump, gpm 175
Total dynamic head, ft. 10
Horsepower 10
Sludge Blending Tanks
Number 2
Dimensions
Diameter, ft. 30
Depth, ft. 12
Total Volume, gal. 127,000
MR Belt Filter Presses
PR
MM
PM
MM
PM
PM
MR
P M
Number 3
Belt width, meters 2
Solids loading rate per press, lb./hr. 1,600
Sludge Drying Beds
Number 36
Dimensions of each bed
Length, ft. 135
Width, ft. 48
Total area, ft.2 233,280
Method of sludge removal Truck -mounted vacuum
Reactor -Clarifiers (for Drying Bed Underdrain Return and Belt Press Filtrate)
Number 2
Diameter, ft. 30
Total surface area, ft.2 1,410
Maximum belt filter press filtrate
(one press standby), gpd 576,000
Overflow rate, gpd/ft.2 410
p., R276/3414-3/072590
5-7

FIGURE 5-1
1
0
1
Rs
Ns
Ns
1
2
3
f I
000000
0
6
7
B
9
10
STRUCTURE LEGEND
• INVE
NNE&
® CAUSTIC STORAGE MOUES
Q BELT FI.1ER PRESSES
® WEND TANKS
© SLUDGE STORAGE TANKS
O GRAMTY 1I CKE ER
Q GAS NO E1
p A
No EI GIE/BLO ER mum
O COMM mote
U AERATION BASIN EFFLUENT CRAM
Ib CHLORINE STORAGE AND FEED FACILITES
H RAS PUMP STATIONS
® IN1fDIC / AERATION TANKS
® Row SLUDGE MMC1IOM BOX
• mite. CLARIFIER/ H OCCU1ATCRS
• EFFLUENT FILTERS
O BEUlENT PUP STAIN
Q REACTOR QNIFERS
▪ REACTOR GAMER PULP STATION
® ANOXIC TANKS
® ALUM S10RAIE AND FEED FAUNS
O FEW tam, TOPICAL
• UL1RA%IOIET OISINFECNON FACIJIES
® SLUDGE DR1sN0 BEDS
® SLUDGE STOCKPILE AREA
• ODOR CONTROL FAISJ1ES
• PRDMARY SEN11910 TAM
p WAS THICKEIMRS
EXPANSION LEGEND
•
EXIS1TNG FACIJI1ES
FACILITIES PROPOI FOR 20 MGD CAPACITY
SCALE : = 2'
FARRINGTON ROAD
WASTEWATER TREATMENT
PLANT
HAZEN AND SAWYER, P.C.
IINGINEERB
RALBOR NORTH CAROLNA

FIGURE 5-2
PLANT
INFLUENT
UR
I
INFLUENT
PUMP
STATION
LEGEND
DS
F
FB
FBR
FE
ML
PE
PS
RAS
sc
SU
TS
TSU
UR
WAS
0
SC
FBR
ALUM
SC
PE
SCREENING PRIMARY PE
AND GRIT -T SETTLING
REMOVAL BASINS (4)
SCUM
CONCENTRATOR
NORMAL OPERATION
ALTERNATE OPERATION
DIGESTED SLUDGE
FILTRATE
FILTER BACKWASH
FILTER BACKWASH RETURN
FILTER EFFLUENT
MIXED LIQUOR
PRIMARY EFFLUENT
PRIMARY SLUDGE
RETURN ACTIVATED SLUDGE
SCUM
DIGESTER SUPERNATANT
THICKENED SLUDGE
THICKENER SUPERNATANT
UNDERDRAIN RETURN
WASTE ACTIVATED SLUDGE
PUMPS
SU
SCREENINGS
AND GRIT
TO LANDFILL
SU
PS
SU
ANOXIC
TANKS
(2)
7
j
RAS
ALUM
OR LIME
MIXING/
AERATION
TANKS (10)
PS
PRIMARY SLUDGE
PUMP STATIONS (2)
,PS
GRAVITY
THICKENER
(I )
TS
L___
WAS T
P
ML
FINAL
CLARIFIERS
(4)
i
GRAVITY BELT
THICKENERS
(2)
ANAEROBIC
DIGESTERS
(2)
� I
L------J
SLUDGE
BLENDING
TANKS
(2)
RAS
PUMP
STATION
()
TSU
TSU
FINAL
CLARIFIER/
FLOCCULATORS
(2)
RAS
PUMP
STATION
(I)
ALUM
ild
EFFLUENT
FILTERS
(4)
FB
ALUM
UR
ULTRAVIOLET
DISINFECTION
POST
AERATION
EFFLUENT TO
NEW HOPE CREEK
SLUDGE
STORAGE
TANKS (2)
DS I
----� DISPOSAL BY
LAND APPLICATION
OF LIQUID SLUDGE
DS
F
r
I
i
J
I
DS
PROCESS FLOW SCHEMATIC
20 MGD DESIGN CAPACITY
(BIOLOGICAL PHOSPHOROUS REMOVAL)
REVISED JULY, 1990
1
UR
REACTOR
CLARIFIERS
(2)
SLUDGE
DRYING
BEDS (36)
BELT
FILTER
PRESSES (3)
J
___ DISPOSAL BY
LAND APPLICATION
TRUCK HAULING TO
NORTHSIDE WWTP
CEMENT KILN
DUST FACIIJTY
FARRINGTON ROAD WASTEWATER
TREATMENT PLANT
HAZEN AND SAWYER, P.C.
ENGINEERS
RALEIGH, NORTH CAROLINA