NC0026051_Permit Modification_20130104

rCDrH-R
North Carolina Department of Environment and Natural Resources
Beverly Eaves Perdue
Governor
Division of Water Quality
Charles Wakild, P.E.
Director
January 4, 2013
Mr. Joseph Pearce, P.E.
Utility Division Manager
County of Durham
Engineering Department/Utility Division
5926 NC Highway 55 East
Durham, North Carolina 27713
Subject: NPDES Permit Modification
Permit Number NCO026051
Durham County Triangle W WTP
Durham County
Dear Mr. Pearce:
Dee Freeman
Secretary
Division personnel have reviewed and approved your application for minor modification of the subject
permit. Accordingly we are forwarding the attached modified permit page. Please remove the existing
"Effluent Limitations and Monitoring Requirements" page and replace it with the one attached to this
letter.
This modification reduces the effluent monitoring frequencies for Biochemical Oxygen Demand
(BODS), Total Suspended Solids (TSS), Ammonia Nitrogen (NH3-N) and Fecal Coliform from daily
(5/week) to 2/week monitoring. The modification was based upon an evaluation of three years of
facility effluent monitoring data. The facility's performance satisfies the criteria established in the
"DWQ Guidance Regarding the Reduction of Monitoring Frequencies in NPDES Permits for
Exceptionally Performing Facilities" as approved by the Director of the Division of Water Quality on
October 22, 2012, and justifies reduced monitoring for these parameters. The modified monitoring
frequencies will become effective on February 1, 2013.
This modification is issued pursuant to the requirements of North Carolina General Statute 143-215.1
and the Memorandum of Agreement between North Carolina and the U.S. Environmental Protection
Agency dated October 15, 2007 (or as subsequently amended).
Please note that this permit is not transferable except after notice to the Division. The Division may
require modification or revocation and reissuance of the permit. This permit does not affect the legal
requirements to obtain other permits which may be required by the Division of Water Quality or
permits required by the Division of Land Resources, the Coastal Area Management Act or any other
Federal or Local governmental permit that may be required.
1617 Mail Service Center, Raleigh, North Carolina 27699-1617 One
Location: 512 N. Salisbury St Ralegh, North Carolina 27604 NorthCarolina
Phone: [phone] FAX: [phone]
Internet www.ncwatefquality.org �atura!!lf
An Equal Oppoa udly 1 Afinab" Action Employer

Mr. Joseph Pearce, P.E.
NC0026051 Modification 01042013
p. 2
If you have any questions concerning this permit, please contact Bob Sledge at telephone number
[phone] or via e-mail at [e-mail].
Sincerely,
Chazles Waki .
cc: Central Files
Raleigh Regional Office/Surface Water Protection Section
NPDES Permit File
ec: Aquatic Toxicology Unit
EPA Region 4 — Ben Ghost

Permit No. NCO026051
A.(1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS
Beginning February 1, 2013 and lasting until expiration, the Permittee is authorized to discharge
treated wastewater from Outfall 001. Such discharges shall be limited and monitored by the Permittee
as specified below:
EFFLUENT
CHARACTERISTICS
EFFLUENT LIMITATIONS
MONITORING REQUIREMENTS
Monthly
Average
Weekly
Average
Daily
Maximum
Measurement
Frequency
Sample Type
Sample Location
Flow
12.0 MGD
Continuous
Recording
Influent or Effluent
Total Monthly Flow (MG)
Monitor & Report
Monthly
Recorded or
Calculated
Influent or Effluent
SOD, 5-day, (20°C) Z
(April 1— October 31)
5.0 mg/L
7.5 mg/L
2/Week
Composite
Influent & Effluent
BOD, 5-day, (20°C) Z
(November 1— March 31)
10.0 mg/L
15.0 mg/L
2/Week
Composite
Influent & Effluent
Total Suspended Solids'
30.0 mg/L
45.0 mg/L
2/Week
Composite
Influent & Effluent
NH3 as N
(April 1-October 31)
1.0 mg/L
3.0 mg/L
2/Week
Composite
Effluent
NH3 as N
(November 1-March 31)
1.8 mg/L
5.4 mg/L
2/Week
Composite
Effluent
Fecal Coliforrn
(geometric mean)
200/100ml-
400/100ml-
2/Week
Grab
Effluent
Dissolved Oxygen
Daily
Grab
Effluent
Temperature (°C)
Daily
Grab
Effluent
pH 4
Daily
Grab
Effluent
Total Residual Chlorines
17 pg/L
Daily
Grab
Effluent
Chloroforms
2/Month
Grab
Effluent
Bromodichloromethane'
1.8 pg/L
Weekly
Grab
Effluent
Dibromochloromethanes
1.3 pg/L
Weekly
Grab
Effluent
TKN
Monitor & Report (mg/L)
Weekly
Composite
Effluent
NO3-N + NOz-N
Monitor & Report (mg/L)
Weekly
Composite
Effluent
Total Nitrogen, TN
Monitor & Report (mg/L)
Weekly
Composite
Effluent
TN Load 6,'
Monitor & Report (Ib/mo)
111,207lb/yr
Monthly
Annually
Calculated
Effluent
Total Phosphorus, TP
Monitor & Report
Weekly
Composite
Effluent
TP Load 6.7
Monitor & Report (lb/mo)
8,4321b/yr
Monthly
Annually
Calculated
Effluent
Total Mercury'
12 ng/L
36 ng/L
Quarterly
Grab
Effluent
Fluoride
1800 pg/L
1800 pg/L
I Weekly
Composite
Effluent
Total Copper
Quarterly
Composite
Effluent
Total Zinc
Quarterly
Composite
Effluent
Chloride
Quarterly
Composite
Effluent
Effluent Pollutant Scan s
See footnote
9
Composite/
Grob
E
Effluent
Chronic Toxicity 10
Quarterly
Composite
Effluent
All footnotes are listed on the following page.

Facility
NPDES Permit
Receiving Stream
Data Period of Review
Reviewed by
Date January 4, 2013
BODs
Permit Limits:
3 Year Average
# Daily Values > 15 mg/L
TSS
Permit Limits:
3 Year Average
Data Review Summary
Monitoring Frequency Reduction Evaluation
Durham County Triangle WWTP
NC0026051
Northeast Creek (WS-IV; NSW in the Cape Fear River Basin)
Northeast Creek is listed as impaired for aquatic life at and downstream
of the discharge point due to WQ standard violations for zinc and
turbidity.
November 2009 — October 2012
Bob Sledge
Summer
Monthly Avg. Weekly Avg.
5.0 mg/L 7.5 mg/L
<2.28 mg/L
0
All Months
Monthly Ave. Weekly Avg.
30.0 mg/L 45.0 mg/L
< 2.46 mg/L
# Daily Values > 60 mg/L 0
NHz-N
Permit Limits: Summer
Monthly Avg. Weekly Avg.
1.0 mg/L 3.0 mg/L
3 Year Average < 0.15 mg/L
# Daily Values > 3.8 mg/L 2
Fecal Coliform
Permit Limits: All Months
Monthly Ave. Weekly Avg.
200/100 ml 400/100 nil
3 Year Geometric Mean < 4
# Daily Values> 400 4
Winter
Monthly Avg.
10.0 mg/L
Winter
Monthly AvQ.
1.8 mg/L
This facility meets the review guidance standards for all eligible parameters.
Weekly Avg.
15.0 mg/L
Weekly Avg
5.4 mg/L

2012 North Carolina 303(d) List -Category 5
Cape Fear River Basin
10-digit Watershed 0303000206
B Everett Jordan Lake -New Hope River
> AU Number
Name
Description
Length or Area Units Classification Category
Category
Rating Use
Reason for Rating Parameter
Year
12-d4it Subwatershed 0303OW20610
.New Hope River-8 Everett Jordan Lak
> 16-41-1-)14)
New Hope Creek
From a point 0.8 mile downstream of Durham County SR 1107 to
1,415.7 FW Acres WS-IV;NSW,CA 5
(including New Hope
confluence with Morgan Creek Arm of New Hope River Arm of B. Everett
Creek Arm of New
Jordan Lake
Hope River Arm of B.
Everett Jordan Lake)
5
Impaired Aquatic Life
Standard Violation Turbidity
2006
12-digit Subwatenhed 030300020605
Northeast Creek
> 16-41-1-17-(0.7)a Northeast Creek From US Hwy 55 to Durham Triangle WWTP 3.3 FW Miles WS-IV;NSW 5
5 Impaired
Aquatic Life
Standard Violation
Copper
2008
5 Impaired
Aquatic Life
Standard Violation
Low Dissolved Oxygen
2008
5 Impaired
Aquatic Life
Standard Violation
Turbidity
2008
> 16-41-1-17-(0.7)bl Northeast Creek From Durham Triangle WWTP to Kit Creek
3.3 FW Miles WS-IV;NSW
5 Impaired
Aquatic Life
Standard Violation
Zinc
2008
5 Impaired
Aquatic Life
Standard Violation
Turbidity
2012
> 16-41-1-17-(0.7)b2 Northeast Creek From Kit Creek to a point 0.5 mile downstream of Panther Creek 3.2 FW Miles WS-IV;NSW
5
Impaired
Aquatic Life
Standard Violation
Copper
2008
5
Impaired
Aquatic Life
Standard Violation
Zinc
2008
5
Impaired
Aquatic Life
Standard Violation
Turbidity
2008
32-digit Subwatershed
E
Friday, August 24, 2012 Approved by EPA August 10, 2012 Page 10 of 170

`
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MONITORING REPONT(MR)
VIOLATIONS for:
R.pm wag. olavlF e.g.. Tdl
PwMt NC(fr261y51
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PERMIT: NC0026051
FACILITY: Durham County
Triangle INNI
COUNTY: Durham
REGION:
Raleigh
Binational Vblallon
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va"rg"N
UNROF
WCUI TED
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all
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Mprin, E.
12-MIO Out
EMwnl
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1N 10 Weekly
agar
Frew yYpletm
No Alan. BPJ
OS-M10 001
Erhanl
Merary. Total aFHg)
05101/10 Weekly
agar
Frpenry.. u
No Aol Fecdry
Canwnhelea�
Begonia, Ena
It.2Lg9 001
EMuenl
NI Artrears Trial lm
112W09 5Xwork
cram
Frp-rc,Vloo.
Nan.
enntent
12-2009 001
Effluent
NI AIr81mn Tolellm
12/26rOB SXweaF
out
FrielVote.Nara
Cm
01-MID 001
Enloe,
N;og.Ama Twil(m
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m,0
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No Action,
nr
E�
C6.M10 001
ETwnl
NerryM. Ammome Totallm
Deal 5X week
m,n
Frt9wnry VolaWn
Na Aolan FeuliN
N) CCncemraWn
Reporter, E-
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EMwm
Nitrogen. Ammoma Tow. lm
11Q,i 5XweeF
all,
Inatanry VaI.
No Atlon. BPJ
NI Cm®nlxtel
11.2009 001
E,ri
So116s. Toler B.o,n..O
1128109 5Xweek
m9e
Frpuenry VuleM
Nan.
Coro hater
12-2009 001
EMwnl
So116s, Total Suapennen-
122WOR SXweek
mill
Fmeuen,Vwlmlon
No-
ConcenlmLon
01-2010 001
EMwnl
SoFft Total Suspended
alaCYlO 6xtowk
mi,a
Frpuenry Viewon
No Alan. Data
C.roartnem
Entry Enter
W.MIO 1101
EMuenl
Stloe. Total SuamMao-
wall SX—a
mgal
Fmymnry V.I.
NoACan ICon®nln—
Rura ing Env
11-2011 Mt
EMuenl
SaI�. Total Suspended
it/2M11 5Xveek
m,n
Frpuenry VaWim
No Alan, BPJ
o —1rzLm
11 -2W9 001
EMuenl
Turre rum. Wager p,
11/2WD9 Sit
Oe,c
Frpuenry VroM4on
None
Cena,rare
MONITORING REPORT(MR)
VIOLATIONS for:
F.,.-+e nm0
pqe rdo
Pemd1. WiL"1 'Il1
Masao., 112(J4
ring 1'.1-2L11_ Perm' I.
V.. Calpory.i
pmyvn Category NPDES WX
Few'Rearm.:
P.Rome. —:
Cia,",
'.
SulAaaln: ::.
vouala
Ato.,-
MeprM.or. -4
PERMIT: NCO026051
FACILITY: Durham County -Triangle Ital
COUNTY: Detrain
REGION:
Raleigh
Northern, Vm1000n
Mualual G OURKLI
VI N
OrATIO
UNIT OF
MOutaTED
gBr,,.T Gail
LOCADOl
pXR/.YEIEA
DATEFREOIIENCV
MEXSURE
LIMB -M {WERLAUT
NOIAFO. TYPE
NOVrTONa 1poaa
12-SYJ9 Wt
EMuenl
AAnnnal Fervent Smn[IM
12111/D9 Ana.uh,
u,n
Frpuercy Ve.
Not
11-2009 .1
EMuenl
BOD, 5-Dey 120 Dp C1
1128109 5Xweek
main
Frpuenry Vmlabm
None
Conrenhaaon
12-2009 all
Effluent
0D. C)
BOO. 5-Day 2p
1W09 5Xweek
22
raga
Frpwncy volawn
Nom
Concanlmon
01-2010 001
EMuam
ROD. 5-0.y (20De,. C)
01ro2/f0 5Xweek
all
Frpueny Veil
No Alan. Dan
Conn otinllan
Entry Errw
Di-MIO 001
EMuenl
SOD C)
Dial 5X creek
man
Frenwnry Val!
No Anaq Faaary
CaaeygunDp,.
Repwl^,Enp
11-M11 .1
EMuenl
B005Dlnaonay20 Call,, C)�
11QW11 5Xweek
nal
Frpuenry VaP.-
NO Ao., all
Cunorn
11_2009 001
EMuenl
Cream. Fool Ill. Ill
112W09 5X week
WIOcm1
Frpwry Valalwn
Rona
Smile .SC
12-2009 001
EMuenl
CdMrm, Fecal MF. M-FC
12RW09 5Xweek
MlWml
Fm9uanry Valalan
li a.
Smith ae5C
06-2010 001
EMuenl
Colifmm. Few I MF. Ml
SBNy10 5X week
./100ml
Frpmnq Venter
No ".I. Fenary
Smith "'51C
Rewning Error
11-2011 001
EMuenl
CWIam, Fowl MF. M-FC
112W11 SXweek
WIDOm1
Frpuenry Valaaon
No Alan. BPJ
BmN 4 5C
11-2009 Oot
Eall
DO, Doti DoonaiI
IIRWO3 SXweek
mgll
Frpwncy Vagal
None
12-2009 Sol
Sal
DO Oal DeseMd
121.01 SXweek
eager
Frpuenry Val.
None
W-410 Sot
EMuenl
DO. Oxygen, DnsNrtd
06105110 SXwek
legal
Fmyum VOMam
NO AIao Feuary
Report., Ena
11-Ali 001
EMuenl
DO. Daryen, Otani
112WI1 5Xweno
mg/I
Frpuenry V.1.1
No Art—, BFJ

MONITORING REPORT(MR) VIOLATIONS for Reommie 0110.:2 Pagc 3ar0
P.R.: lti,6]NO51 MRe Bebeerr: '.2C.5 eeN IOQ01^„ Regi. °-, VuMlion Celegary. 5, pmgram Lelegwy: NPOES A"N
F,oW, Na—'.i. Param Na, °A County r. Subbea'mI
Moor Miror'.
PERMIT: NC0026051 FACILITY: Durham County-Trlmgte VANTIa COUNTY: Durham REGION: Raielgh
MONITORING OI ALLI
NCUTGN
UNITOF
R LCUt TEG
REPORT
PPI
LOUTNM
PANAMETER
COTE FREQUENCY
MEATORE
LIMIT VALUE %OVERLIMIT
VIOLIORON TYPE
NOI NA LGN
12.2006
001
EMumt
Water Deg,
122NW 5Xwaek
Lou
Frepuenq Mm.tl
Nana
To ere,
rolina
w6 Ml0
001
EMuent
T—Paratun, W&er Deg.
06TY10 5Xwanc
Oegc
Fequer, Vblellcn
Na Adbn, Faally
Cenkgra0e
Reporting Enor
11-2011
OM
EMuent
TempemNre, Water Deg,
11wil 5XY.eek
as,c
Frepumry V.W.
No Adbn, 6PJ
CenNgraae
11-2009
001
EMum1
pH
ilUarM 5Xweek
au
Fn,u VWkxan
None
12-Mot,
001
EMwn1
pH
1TYL" 5Xweek
au
FryuMy Viour.
Nona
X-A10
001
Entrant
pH
MAMMO 5Xwxk
au
Flegue"V.I..
No A..R F&.M,
ReOod, Enw
11 .2011
001
EMuenl
PH
11OWli 5Xweek
au
Frequency V.I.
No An, BPJ
Other Violallon
MONITORING
OUTFALLI
AOL"ho
UNITOF
CALCULATE"
REPORT
PPI
LOGTIXI
PARNAETER
DOTE FREOLENCV
MEASURE
LIMIT U..L RL1MIT
VOIATION TYPE
VIOUTONACIION
01.2012
GIMW12
Aquatic Were pwmitfml
PWce dwwvnn
MONITORING ou TALLI
VIOLATION
UNIT OF
CALwut£➢
SPORT
I
LOCATNW IMNAMEIER
DARE FREQUENCY
MEASURE
UNIT VALUE %OVER LIMIT MIARON TYPE
"ORATION ACTION
01-2010
001
EMIwnR Annual Pollutant Sum 1126
DIM1110 ARR,,
ug9
Pammeler, Missing
None
peremelersl
W-who
001
EMRR, Annual Pdlutani Son 1126
OIYJVIO Annue,,
yae=l lw=
Peremele,RmnlodwthnvMk No nun, RIMS
n ltamwbrsl
Umld Maasure
Celculapan Erm

Permit: NC0026051
Region: Raleigh
Penalty
Assessment
Case Number Approved
Penalty
Amount
Permit Enforcement History by Permit
Facility: Triangle WWTP
County: Durham
Remission Enforcement EMC
Enforcement Request Conference Hearing
Costs Damages Received Held Held
Owner: Durham County
Collection
Memo Sent
to AGO Total Paid Balance Due
Has
Payment
Plan
Case
Closed
WQ-1986-0083
02/05/87
$20,000.00
$.00
$.00
$5,500.00
.00
No
06/16/87
LT-1993-0006
10/25/93
$500.00
$.00
$.00
$500.00
.00
No
02/02/94
FK-1998-0001
01/26/98
$352.88
$342.80
$695.68
.00
No
02118/99
DV-1997-0017
03/18/98
$8.000.00
$1,745.66
04/23/98
05/27/98
$9,745.66
.00
No
OM1198
LV-1999-0169
05/04/99
$1,000.00
$49.62
$1,049.62
.00
No
06/03/99
LM-199M036
05/21/99
$1,850.00
$57.42
$557.42
.00
No
1022/99
LV-2001-0473
1127101
$2,000.00
$45.27
$45.27
2,000.00
No
LV-2001-0658
01/02/02
$2,250.00
$45.27
$45.27
2,250.00
No
LV-2002-0347
09/16/02
$1,250.00
$45.27
$1,295.27
.00
No
10/22/02
LV-2003-0011
01/13/03
$250.00
$45.27
$295.27
.00
No
02/24/03
LV-2003-0635
10/09/03
$500.00
$45.27
$545.27
.00
No
11/17/03
LV-2003-0646
10/24/03
$4,500.00
$45.27
$4,545.27
.00
No
12/01103
LV-2008-0412
11/07/08
$500.00
$110.73
$610.73
.00
No
12/16/08
Total Cases: 13
Total Penalties:
$42,600.00
$2,587.93
$45,530.73
25,430.73
Total Penalties after remisslon(s):
$4,250.00
$29,530.73

i�'�✓Ltd
LINTY OF DURHAM
ENGINEERING DEPARTMENT
,�LITY DIVISION
/ November 1, 2012
Return Receipt Requested
Certified Mail # 7007 0220 0004 2885 9260
Mr. Charles Wakild
Director
NCDENR — Division of Water Quality
1617 Mail Service Center
Raleigh, NC 27699-1617
Re: Minor Modification Request to NPDES Permit # NCO026051
Dear Mr. Wakild:
Durham County requests a minor modification of NPDES Permit #NC0026051 in accordance with the
October 22, 2012, "DWQ Guidance Regarding the Reduction of Monitoring.iirequencies in NPDES
Permits for Exceptionally Performing Facilities". There are nine criteria listed and Durham County has
closely evaluated our Facility, the Triangle Wastewater Treatment Plant, and finds that it meets the
criteria. Specifically:
1. The Facility has no civil penalty assessments for permit limit violations for each target parameter
during the previous three years.
2. Neither the petmittee nor any of its employees have been convicted of criminal violations of the
Clean Water Act within the previous five years.
3. The Facility is not currently under an SOC for target parameter effluent limit noncompliance.
4. The Facility is not on EPA's Quarterly Noncompliance Report for target parameter limit
noncompliance.
5. For BOD5, TSS, N113-N, and fecal coliform, the three year means of effluent data is less than 50
percent of the monthly average permit limit. A table of the Monthly Average Permit Limits, 50%
criteria, and 3-year means is attached.
6. No more than 15 daily sampling results over the three year period exceed 200% of the monthly or
weekly average limit for BOD5, TSS, and N113-N. A table of the Monthly and Weekly Average
Permit Limits, 200% criteria for each, and 200% criteria exceedance count is attached. Please
note the summer limits were used since they are the lowest.
7. No more than 20 daily sampling results exceed 200% of the weekly average permit limit for fecal
coliform. A table of the weekly average permit limit, 200% criteria, and 200% criteria
exceedance count is attached.
8. For the four target parameters, there are no limit violations.
9. Reduced effluent monitoring will not impair assessment of sensitive downstream uses.
TRIANGLE WASTEWATER TREATMENT PLANT
5926 NC Highway 55 East, Durham, N.C. 27713 • [phone] • Fax [phone]
Equal Employment/Affirmative Action Employer

Based on the data attached and on the approval criteria in "DWQ Guidance Regarding the Reduction of
Monitoring Frequencies in NPDES Permits for Exceptionally Performing Facilities", Durham County
TWWTP meets all the criteria. Durham County is requesting a minor permit modification to reduce the
monitoring requirements for BOD5, TSS, NH3-N, and fecal coliform in NPDES Permit number
NC0026051 from five times a week to two times a week.
Thank you for considering the request. If you have any questions call me at [phone].
S ncerel,, u2r
Jo ph : Pearce, PE
Utility Division Manager/POTW Director
Enc: Durham County TWWTP Effluent Data
cc: Jeff Poupart, NCDWQ Point Source Branch Supervisor
Stephanie Brixey, Compliance Manager
1.' W

Durham County TWWTP Effluent Summary
50% of the Monthly Average Permit Limit
50%
50%
Monthly
Monthly
Monthly
Average
Average
Average
Parameter
Permit Limit
Permit Limit
3 year Mean
Criteria Met
BOD5 (mg/1)
5
2.5
1.1
yes
TSS (mg/1)
30
15
0.9
yes
NH3-N (mg/1)
1
0.5
0.1
yes
Fecal Coliform
(colonies/100 ml)
200
100
6
yes

200% of Weekly/Monthly Average Individual Sample Count
Number of
Number of
200% of
Daily
200% of
Daily
Weekly
Weekly
Samples
<15/20
Monthly
Monthly
Samples
<15/20
Average
Average
over the
Samples
Average
Average
over the
Samples
Parameter
Permit Limit
Permit Limit
200%
Criteria Met
Permit Limit
Permit Limit
200%
Criteria Met
BOD5 (mg/1)
7.5
15
0
yes
5
10
0
yes
TSS (mg/1)
45
90
0
yes
30
60
0
yes
NH3-N (mg/1)
3
6
0
yes
1
2
4
yes
Fecal Coliform
(colonies/100 ml)
400
800
5
yes
200
400
7
yes
*(for BOD5 and NH3-N, summer limits were used since they are the lowest)

Durham County TWWTP Effluent Monthly Averages
BOD5 (mg/1)
TSS (mg/1)
Ammonia (mg/1)
Fecal (colonies/] 00ml)
October 2009
1
3.5
0
3
November 2009
1
3.7
0
7
December 2009
0.6
1.2
0.1
4
January 2010
1.1
1.6
0
2
February 2010
1.1
1.6
0
2
March 2010
1
1.3
0
5
April 2010
1.4
1.6
0
3
May 2010
1.3
2.1
0
7
June 2010
0.2
2.1
0.1
4
July 2010
0.9
1.3
0.1
4
August 2010
0.9
1.5
0
18
September 2010
1.7
0.6
0.2
16
October 2010
1.9
0.7
0.1
4
November 2010
0.7
0.7
0
2
December 2010
0.7
0.4
0.1
3
January 2011
0.9
0.6
0
2
February 2011
1.3
0.4
0
2
March 2011
1.5
0.3
0
3
April 2011
2
0.8
0.1
3
May 2011
3
1.2
0
2
June 2011
2.4
0.7
0.1
9
July 2011
1.6
0
0
21
August 2011
1.2
0
0.1
12
September 2011
1.1
0
0.5
9
October 2011
0.8
0
0
3
November 2011
0.6
0.1
0
3
December 2011
0.1
0
0
4
January 2012
0.2
0.1
0
2
February 2012
0.5
0.1
0
2
March 2012
0.6
0.5
0.2
3
April 2012
0.1
0
0.1
10
May 2012
0.4
0.7
0
10
June 2012
0.7
0.6
0
3
July 2012
1.2
0.1
0.2
7
August 2012
1.2
0.2
0.5
7
September 2012
1.6
0.3
0.1
7
3 year average
1.1
0.9
0.1
6
Number above monthly
average permit limit
0
0
5
6
Permitted Monthly
Average*
5
30
1
200
*(for BODS & NH3-N, summer limits were used since they are the lowest)

Durham County'TWWTP Effluent Data
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Durham County TWWTP Effluent Data
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Durham County TWWTP Effluent Data
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Durham County TWWTP Effluent Data
Few
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Durham County TWWTP Effluent Data
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Durham County TWWTP Effluent Data
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Durham County TWWTP Effluent Data
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Durham County TWWTP Effluent Data
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Durham County TWWTP Effluent Data
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Durham County TWWTP Effluent Data
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Durham County TWWTP Effluent Data
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Durham County TWWTP Effluent Data
WA = weekly average
MA = monthly average
*denotes geometric mean was used
Non -compliant
Compliant
Page 26