NC0026441_Fact Sheet_20140327

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FACT SHEET FOR NPDES PERMIT DEVELOPMENT
NCO026441 Siler City WWTP
Facility Information
_Facility Name:................................................................:.._Siler City WWTP Count ......................................................................................._Chatham County
_.:._. ._...._._.-.-......
PermittedFlow MGD: 4.0 MGD Regional Office: Ralei.._._...._...._._._._._......._....................................................................._.......................,........................................................._..._._._._._._._._._.-._._._._._..._._.:.
............... ............._.............
..._._._ac..._1............_.._ass........................................................................WW IV USGS Topo Quad......................................t.._E21NW
_. . .
Pretreatment..P.....mgja......m........: Full LTMP USGS Quad Name: Siler. City...................I............... .... ............ ..... ......._ ......... ......._........ ...._.;.................... ..._.......
Permit Status: 1 Expired/Renewal
Stream Characteristics
...Receiv.... ..Stream.: Loves Creek................._...._........................................._ (D (miz)
... ..................
rainage Area 7.9
River Basin: .......................... Fear..........................._................ .............................. .......... _ .....
Sub-basin: 03-06-12 Summer 7 10 cfs : 0.25
....................................................................................................:............................._.-._._._._..................................................................................._._._._.................................._Q............_(......,...).........................................................................._._..._._._._._......._._.........................._.
Stream Assessment Unit: 17-43-1Oc Winter 7010(cfs): 0.4
.......................-._._._._......................................................................... _._._._...._.....................................................................................................:..............
3
Stream Classifi ........................_........._._._._._...._......................_....._...
canon. 0 ..............._.__...._...._..............._..............................................OQ2....(cfs)_..........................................................................................................................._..............-._.........
.._...._._....................... .....
........... _._.
303(d)Status: Listed on Final 2012 Average Flow(cfs): 8.7
......................................................._._._._._._.-................................_._.._....
303(d)list for Aquatic life 1 IWC %: 96.1
-Impaired biological _._...................._..............................................................................................._......................................................_........................................
integrity Benthos. HUC: € 030300030503
Summary:
The Siler City WWTP is rated at 4.0 MGD. It is an activated sludge secondary treatment system with
tertiary filtration. The plant serves 7,877 people along with commercial and one SILT-Brookwood
Farms, Inc. Siler City has lost most of it's industries over the past few years, loosing two major chicken
processing facilities and one textile facility. The lost industry represented over 1 MGD of wastewater,
and five million dollars per year City Water demand. Loss of industries, and the population and
revenue from them,has severely impaired the Town's finances.
The WWTP discharges into Loves Creek,which is a tributary to Rocky River,which in turn flows into
the Deep River before it joins the Haw River to form the Cape Fear River. Loves Creek and Rocky
River have experienced problems with high nutrients, algae,Low Dissolved Oxygen and Periphyton for
many years. The Siler City WWTP is the only Major WWTP in this part of the Cape Fear basin,but it
is not the only source of nutrients, as Loves Creek is impaired above the discharge as well as below,
Rocky River is also impaired for chlorophyll-a above the confluence with Loves Creek.
The 2012 303(d)final list of Impaired Waters lists Loves Creek as Impaired for Ecological/biological
Integrity Benthos from the source to Chatham Avenue. Loves Creek is listed as Impaired for Low
Dissolved Oxygen from Chatham Avenue to the Siler City WWTP, and is listed as Impaired for
Ecological/biological Integrity Benthos from the WWTP to Rocky River. The current Cape Fear Basin
Plan gives potential sources as stormwater(MS4 NPDES)and the WWTP. The basin plan goes on to
state"a stressor study completed in the Loves Creek watershed indicated toxic chemicals in runoff from
Siler City are the main stressors to the benthic community. Streambank erosion, sedimentation, and
excessive algal growth are also stressors. The WWTP was not the main stressor,and agricultural land
uses are also a source. The study noted runoff from animal operations in the upper watershed might be
contributing nutrients and bacteria to the creek." The basin plan recommends that the Division continue
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NPDES Permit Fact Sheet Siler City WWTP
Page 2 NCO026441
to monitor the Loves Creek watershed and work with DSWC to evaluate if BMPs can be implemented
to reduce nutrients from animal operations in the watershed.
The 2012 303(d)final list of Impaired Waters lists Rocky River in the Upper Siler City Reservoir to the
dam as Impaired for Chlorophyll-a and Low Dissolved Oxygen. From the lower Siler City Reservoir
dam to Varnal Creek,Rocky River is listed as Impaired for Low Dissolved Oxygen. Rocky River is
listed as Impaired for Chlorophyll-a behind Woody's Dam. The current Basin Plan states "The Siler
City WWTP, as well as agriculture and residential activities,are potential sources of nutrients."
The Siler City WWTP currently has total phosphorus and ammonia limits that are more stringent than
those of many similar facilities statewide. Total Nitrogen and Nitrate-Nitrogen levels in the WWTP
effluent have decreased greatly after the closure of the two poultry processing plants in 2008 and 2011,
but remain higher than they should be. The facility has been encouraged to implement any simple
process changes to denitrify and reduce NO3-N in the effluent.
Data Review:
Monthly average DMR data was reviewed for the period of January 2011 through April 2013. That
data is summarized below in Table 1. Monthly average flows are at 39% of permitted capacity
with maximum monthly average flows at 54% capacity.
Table 1: Summary of Monthly Average DMR data- 1/2011-4/2013
Fecal
Flow PH TRC BOD NH3-N TSS (#/100 D.O. TN TP
(MGD SU /L m /L m /L m /L mL m 2 (Mg/Li m /L
Ay_, 1.57 7.4 1 1.19 1.2 1 0.43 1.0 3.9 8.95 17 0.072
Max 2.15 8.3 3.0 4.1 1.22 3.6 25 10.90 30.2 0.644
Min 0.157 6.4 <10 0.1 0.04 0.1 1 6.90 8.4 0.005
Limit 4.0 6-9 17 5 (s) 1 (s) 30 200 >6 0.5 (S)
10(w) 2(w) I I — 2.0(W
The facility had one permit limit violation during the review period,which was a failure of a WET
test in March,2013. The facility had passed the 20 previous quarterly tests, and passed the two
subsequent tests.
RPA Analysis:
The facility is required to monitor for copper, zinc and chlorides as part of the NPDES permit, all
are considered as Action Level parameters. RPAs were performed for each of these parameters and
all showed reasonable potential to exceed action level standards. The facility has passed 22 of 23
Quarterly WET tests since 2008. One failure occurred in March, 2013,but the facility passed the 2
follow up tests, and passed the next 2 quarterly tests. No toxicity is caused; monitoring will remain
with no limits. Monitoring frequency will be changed to Quarterly from 2 per month in conjunction
with Chronic Toxicity testing in accordance with the Division's Permitting Strategy for metals and
toxicants.
The facility is also required to monitor for arsenic, cadmium, chromium, lead,molybdenum,nickel,
mercury and selenium as part of its pretreatment program. RPA of data showed only cadmium was
detected above the allowable concentration during the 2-yr data review period. The reported values

` NPDES Permit Fact Sheet Siler City WWTP
Page 3 NCO026441
were 3,4, and 3 µg/L, compared to the allowable concentration of 2.1 µg/L. Limits and Monthly
Monitoring for cadmium were added to the permit as there was more than one value above the
allowable concentration. An 18 month compliance schedule has been added to provide time to
analyze 12 monthly samples. If none are greater than detect or if RPA shows no RP,the permittee
may petition the Division to remove the limits and monitoring from the permit. Monitoring would
still be maintained on the LTMP. If RP is determined,the limits will remain in the permit,
beginning on November 1, 2015.
Mercury data did not show reasonable potential to cause an exceedence of water quality standards.
An analysis of mercury data according to the Statewide Mercury TMDL show that no mercury limit
is required,that three PPA analysis of mercury data will be sufficient, and that a Mercury
Minimization Plan is required.
Instream Data Review:
Siler City WWTP is a member of the Upper Cape Fear River Basin Association(UCFRBA). The
UCFRBA performs instream monitoring on the Rocky River at a station 900 feet upstream of the
confluence with Loves Creek, and another station 4 miles downstream. They also monitor Loves
Creek upstream and downstream of the discharge point. Instream data was reviewed for the period
of January 2011 through March 2013. A data summary is provided in tables 2 and 3. Based on this
data, it does appear that both Loves Creek and Rocky River are experiencing elevated nitrite/nitrate
levels,however the levels are greatly reduced from prior levels due to the closing of two poultry
processing facilities. Dissolved oxygen is better downstream than upstream in both streams.
Table 2: Summary of UCFRBA Data from 2011-March 2013 -Loves Creek
Parameter Up stream-B5890000 Downstream-B5920000
Average Max Min Average Max Min
DO(mg/L) 7.16 12.31 2.23 8.58 12.38 6.39
pH(su) 6.91 7.61 6.23 7.55 8.07 6.71
TSS(mg/L) 6.5 38 2.5 5.25 14 2.50
Turbidity(NTU) 9.9 49.8 1.7 4.9 37.5 0.6
N 113 N(mg/L) 0.06 1.41 0.02 0.18 1.75 0.02
TKN_N(mg/L) 0.56 1.41 0.29 0.67 2.61 0.20
02/NO3_N(mg/L) 0.61 4.78 0.02 13.6 36.4 0.42
TP(mg/L) 0.068 0.170 1 0.023 0.061 0.147 1 0.026
Table 3: Summary of UCFRBA Data from 2011-March 2013-Rocky River
Parameter UP ream-B5950000 Downstream-135980000
Average Max Min Average Max Min
DO(mg/L) 6.00 12.53 1.62 6.92 12.09 4.18
pH(su) 6.66 7.33 5.84 6.98 7.42 5.95
SS(mg/L) 10.55 88 3 6.53 15 2.5
Turbidity(NTU) 8.48 34.3 3.3 7.05 21.7 1.9
I-f 3_N(mg/L) 0.12 0.67 0.02 0.06 0.2 0.02
TKN N(mg/L) 1.02 1.42 0.56 0.84 1.51 0.02
O2/NO3 N(mg/L) 0.29 1.05 0.02 3.21 1 9.89 0.53
TP(mg/L) 0.103 0.410 0.0,46 0.079 0.174 0.024

NPDES Permit Fact Sheet Siler City WWTP '
Page NCO026441
WET Test Results.-
Siler City WWTP has a chronic whole effluent toxicity testing requirement at 90%effluent
concentration. From March 2008 through September 2013 they have passed 22/23 WET tests. In
March 2013 there was one failure,which resulted in an NOV, but no enforcement taken. The
facility was required to test in the following two consecutive months and passed both of those tests,
and passed the next two scheduled tests in June and September 2013.
Correspondence File Review/Compliance History
There have been no violations of the facility's permit limits (with the exception of the above
mentioned WET test failure)from January 2011 through September 2013. Inspection reports
indicate that the facility is properly maintained and has made efforts over the years to better
organize their filing systems. Several inspections did note,going back to 2004,that there is not
enough standby power to operate the entire facility. The generator can only operate the influent
pump station,bar screen, and grit removal processes. The inspectors recommend that the town
consider adding generator capacity to avoid a potential discharge of partially treated wastewater to
Loves Creek in the event of a power outage. The June 14,2012 Compliance Inspection Report
states that Influent Equalization Basin 4 A&B are isolated and locked out of service due to severe
structural damage, and should be repaired. This repair should be completed prior to adding any
additional flow, regardless of nutrient loading. Excessive I&I seems to be a problem too. Flow
went from 1.625 MGD on June 5 to 3.022 MGD on June 6 to 6.365 MGD on June 7, 2013.
Permit History:
Refer to NCO026441 Attachment I Siler City NPDES Permit History.
Proposed Changes Incorporated into Permit Renewal
1. Changed 'Division of Water Quality"to "Division of Water Resources" on Permit.
a. Changed Director to Thomas A.Reeder.
b. Changed expiration date to 4/30/2019 from the scheduled expiration date of
10/31/2016 in order to provide 5 full years of permit.life,as the permit had expired
on 10/31/2011. This will put the permit out of synch with the other permits in the
subbasin, so renewal will be for a shorter time in order to get it back on schedule.
2. On Supplement to Cover Sheet,updated the equipment description.
3. On Sheet A.(l)EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS:
a. Moved pH and Dissolved Oxygen requirements up to the table and deleted their
footnotes.
b. Added Monthly monitoring for Total Cadmium to the permit with new Monthly
Average and Daily Maximum limits,based on statistical analysis of LTMP data.
Cadmium had previously been monitored only on the LTMP. A Compliance
Schedule of 18 months is provided. If 12 months of cadmium data shows no
detects, or if RPA shows no RP,the facility can petition the Division to remove
cadmium limits and monitoring from the permit. Cadmium monitoring would
remain in the LTMP. This would not require a public notice. If data do show RP,
the limits become enforceable on November 1, 2015 (18 months after permit
effective date).
c. Monitoring for Copper,Zinc and Chloride has been changed to Quarterly from
2 per week. See RPA Analysis:section above.
d. TN monitoring has been corrected to"Calculated"from"Composite".
4. Removed old Condition A.(3) Nutrient Optimization Plan as it has been completed.
5. Added new special condition A.(3) NUTRIENT REOPENER to require the Town to report any
plans to accept new industrial process wastewater with TN or TP concentrations higher

` NPDES Permit Fact Sheet Siler City WWTP
Page 5 NCO026441
than 40 mg/L TN or 5 µg/L TP. The Division could modify the permit according to the
changed characteristics of effluent, or add or change TN and/or TP limits.
6. Renumbered existing Condition A.0) Chronic Toxicity Permit Limit to A.(8)and updated
the language to the current version.
7. Added new Condition A(4)NUTRIENT WATER QUALITY MODELING REOPENER
in accordance with the Basinwide Nutrient monitoring program.
8. Renumbered existing Condition A.(5)Effluent Pollutant Scan to A.(9). Updated permit
language to the current version,requiring 3 PPAs to be conducted in specified years.
9. Added new Condition A.(5) Mercury Minimization Plan(MMP)as required by the
Implementation Plan for Mercury TMDL. The plan must be developed by October 1, 2014
(six months after the permit effective date).
10. Added new condition A.(6)re cadmium compliance schedule.
11. Added new Condition A.(7)ELECTRONIC REPORTING OF DISCHARGE
MONITORING REPORTS in accordance with EPA requirements for electronic DMR
reporting. Electronic DMRs must be submitted starting on or before January 26,2015 (270
days after the permit effective date.
Basis for Limits
• Flow limits in the permit are based on design capacity for the treatment system.
• Limits in the permit for Fecal Coliform, Total Residual Chlorine(TRC),pH and Dissolved
Oxygen(DO) are based on North Carolina water quality standards [15A NCAC 2B .0200].
• Limits in the permit for Total Suspended Solids(TSS)are based on requirements of 40
CFR 133.102.
• Limits in the permit for BOD and Ammonia—Nitrogen are based on the results of a water
quality model to protect instream dissolved oxygen, and to prevent ammonia toxicity to
aquatic life in the low flow stream(IWC=96.1%).
• Limits for Total Phosphorus(TP)are based on an analysis of nutrients at Siler City WWTP
conducted by the Water Quality Section of the NC Department of Environment,Health and
Natural Resources in May 1991,which recommended summer limits of 0.5 mg/L TP in the
effluent. This was augmented by the Hearing Officer's Report of the court case contesting
the 2007 renewal of the Siler City NPDES permit. He recommended adding a 2.0 mg/L
TP limit in winter.
• Limits for Cadmium are based on an EPA approved statistical analysis of LTMP data
reported on DMRs, for Aquatic Life protection per NC WQS.
Proposed Schedule for Permit Issuance
Draft Permit to Public Notice: September,2013
Permit Scheduled to Issue: March, 2014
State Contact Information
If you have any questions on any of the above information or on the attached permit, please contact
Tom Belnick at(919) 807-6390, or by email at [e-mail].
NPDES Recommendation by:
Signature Prepared by Jim McKay Date 3/27/2014

NCO026441 Attachment I
Siler City NPDES Permit History
• The Rocky River and Loves Creek tributary have long been troubled by high nutrients,low DO,poor
benthics and high chlorophyll-a. Based on the 2012 Integrated Report:
a. Upper Rocky River Reservoir is impaired due to Chlorophyll-a standard violations and Low DO.
b. Rocky River(from dam at lower reservoir to Vernal Creek)is impaired for low Dissolved Oxygen.
c. Rocky River behind Woody's Dam is impaired for chlorophyll-a standards violation.
d. Loves Creek from Source to Chatham Avenue in Siler City is impaired for Benthic macroinvertabrates.
From Chatham Avenue to the Siler City WWTP it is impaired for low DO,and from the WWTP to
Rocky River,it is impaired for Benthic Macroinvertabrates.
e. Tick Creek is impaired for Fish Community.
£ Bear Creek is impaired for Benthic macroinvertabrates.
• Both Loves Creek and Rocky River were impaired both upstream and downstream of the Siler City WWTP
discharge into Loves Creek,but the WWTP was suspected of causing the high nutrient problems and
impairments.
• Permit renewal application submitted April 25,2006. A permit renewal draft was prepared and issued for
public review and comments September 12,2007.
• Due to the many public comments and concerns,a public hearing was held on April 17 2008. Based on
recommendations of the hearing officers,the division added to the permit:
a. Winter total Phosphorus(TP)limits of 2.0 mg/L in addition to the existing summer limit of 0.5 mg/L.
b. Increased frequency of effluent TN and TP monitoring to weekly from monthly.
c. Reporting of TN,NOZ and NO3,and TKN effluent concentrations in addition to parameters already
reported.
d. Instream monitoring on Loves Creek Upstream and Downstream of the discharge. Upstream and
Downstream monitoring on the Rocky River was already in the permit.
e. Development of a Nutrient Removal Optimization Plan was required within one year of the permit
effective date.
• The permit was issued on August 29,2008,expiring on October 31,2011.
• The Friends of Rocky River and the Rocky River Heritage Foundation contested the permit.
Administrative Law Judge Beecher R. Gray heard the proceedings during June,2009. The A.L.J. issued a
decision recommending that the EMC affirm the reissuance of the permit. The EMC affirmed the renewal
of the permit on January 13,2010.
• The permit was issued February 22,2010, still expiring on October 31,2011 with two changes:
a. The Permit effective date changed to April 1,2010.
b. Footnotes on the Effluent Limitations and Monitoring Requirements sheet A.(1)were updated to
include revised TRC thresholds in keeping with Division permitting strategy for Total Residual
Chlorine.
• Siler City lost its two poultry processing industries. The first one in May,2008,and the second in October,
2011. This caused the Total Nitrogen discharged in effluent to decline significantly.
• This permit expired on October 31,2011. A renewal application was received in May,2011.
• Due to staff constraints and a very heavy workload,renewal efforts were made as time allowed.The
renewal draft was issued for public comment on September 25,2013. Numerous comments and requests
for changes were discussed with both Siler City and their consultants,and The Friends of Rocky River and
their attorney, and proposals and counterproposals made. The permit is finally ready to issue in March
2014.
L
Signed: P1`Y_11 Date:

Freshwater<RPA
REQUIRED DATA ENTRY
Table 1. Project Information Table 2. Parameters of Concern La
CHECK if H{W or OWN only Name Type Chronic Modifier Acute,, PQL Units 2
Facility Name SHer
�.
City WWTP Paro1 C 50 FW .
WWTPIINTP Class WW-4 Par02 Arsenic C 10 HHANISF:
- ❑
NPOES Permit NCO026441 Paro3
NC - ❑
6 5 FW
Outfall 001 Par04 Cadmit0i NC,: 2 FW
15 �
Flow,Qw(MGD) 4.0 PaM, Ct (AL) NC. 230 FW eng/L ❑
Receiving Stream Loves Creek Paros
. - ❑
Cesrrrrated P) E�c►mpoktR NC 1 A
Stream Class C Par07 Taal­Phe offe Con"'Unft KC:: 300 -A
7Q10s{cfs) 0.25 Paroa Chromium NG 5U F�If 1; tom. ❑
7Q10w(cfs) 0.40 Paros Copes(AL)
NO 7., FW 73 ❑
30Q2(cfs) Par10 Cyarride tC 5 FVII ?2 I O
QA(cfs) &70 Par11 Fluoride NC' '1,a F'V (❑
1 Q10s(cfs) (L21 Par12! Lead NC 25 FW 33.8 ugJL ❑
Data Source(s) DiMAARs,LT�RP,3 PPAs Par13 Mercury NC 12 FW 0.5 n❑ CHECK forzHol]EL Par14, MGbtdemn NC 2,000 HH--
UOIL ❑
Par15 t lael NC 88 FW 261 ug. ❑
Parl 6 Selenium NC.. b FIN 56 ugh 10
PaM7 Sllrtea'(AL) NC 04.6 FIN 1,.23
Parts Zinc(AL) NC 60 FW 67
FQMDW droodam for date erWy.to some cases a Par19
Chloroform C 170 HH
�rrarren!1ru chOfaes mr a Parzo Dichlorabromamethane C 17 HH wide a Jest you Trey$eEecf µg&
froa1.Effor rrmsago O=rff data er*y does net Par21
meet ictrt crrfa
_ I Par22' ❑❑
NCO0264.41 RPA.xlsm,input
1 011 7/201 3

Siler City WWTP REASONABLE POTENTIAL ANALYSIS Outfall 001
NCO026441 Qw = 4 MGD
Qw(MGD)= 4.00 WWTP/WTP Class: WW-4
1Q10S(cfs)= 0.21 IWC @1Q10S = 96.72%
7QIOS(cfs)= 0.25 IWC @ 7Q10S= 96.12%
7Q10W(cfs)= 0.40 IWC @ 7Q10W= 93.940/6
30Q2(cfs)= NO 30Q2 DATA 1WC @ 30Q2= N/A
Avg.Stream Flow,QA(cfs)= 8.70 IWC @ QA= 41.61%
Receiving Stream: Loves Creek Stream Class: C CHRONIC TEST CONCENTRATION=DEFAULT%
=90%
PARAMETER TYPE STANDARDS&CRITERIA(2) y REASONABLE POTENTIAL RESULTS
-i RECOMMENDED ACTION
(1) NC WQS/ Applied 'h FAV/ a z Max Fred
Chronic Standard Acute n It Det. Cw Allowable Cw
Arsenic Acute: NO WQS
C 50 FW(7QIOs) ug/L 8 0 16.7
Note:n 5 9 Default C.V. Chronic:— — 52.0--
_ NO Detects'No RP Continue to monitor via LIMP
Limited data set No value Allowable Cw
Arsenic C 10 HH/WS(Qavg) ug/L 8 0 16.7 Chronic:---- 24.0
Note:us 9 Default C.V. No value>Allowuble Cw No Detects,No RP. Continue to monitor via LTMP
Acute: 15.5 No RP,Predicted Max>50%of Allowable Cw-
Cadmium NC 2 FW(7QIOs) 15 ug/L 9 3 12.6 _ _ _ apply Quarterly Monitoring
Note:n59 Default C.V. Chronic-- — —2.1 --- — '--------------------
Limited data set 3 value(s)>Allowable Cw R;P for non-AL-apply Monthly Monitoring with Limit
Chlorides(AL) NC 230 FW(7QIOs) mg/L 56 56 302 Acute: NO WQS_ _
Chronic:— — 239 ,R'for AL(Cu,Zn,Ag,Fe;CI)-apply Quarterly --
No value>Allowable Cw Monitoring in conjunction with TOX Test
Acute: 1,056.7 No Detects,No RP Continue to monitor via LTMP
Chromium NC 50 FW(7QIOs) 1022 ug/L 9 0 2.5 _ _
Note:n<_9 Default C.V. Chronic: 52.0I
Limited data set No value>Allowable Cw
Copper(AL) No Detects,Na RP. Continue to monitor via LTMP
Acute: 7.5 RP for AL(Cu,Zn,Ag Fe,CI)-apply Quarterly
NC 7 FW(7QIOs) 7.3 ug/L 56 40 71 _ _ :Monitoring in conjunction with TOX Test
Chronic:— — —7.3 IMP for AL(Cu,Zn,Ag,Fe,GI)-apply Quarterly —
15 values >Allowable Cw Monitoring in:conjunction with TOX Test
Acute: 34.9 No Detects No RP Continue to monitor via LTIVIP
Lead NC 25 FW(7Q10s) 33.8 ug/L 9 0 15.8 _ _
Note:n<_9 DefaultC.V. Chronic:---- ----- -------------------'--`--`—
Limited data set No value>Allowable Cw No Detects,No RP. Continue to monitor via LTMP
Acute: NO WQS
Mercury NC 12 FW(7QIOs) 0.5 ng/L 9 8 13.0 _ _ _
Note:n 5 9 Default C.V. Chronic: 12.5 PerTMDL,No Limit,MIUIP is Required. 3 PPAs+
Limited data set No value>Allowable Cw LTMP monitoring only.
Molybdenum NC 2000 HH(7QIOs) ug/L 9 1 25.3 Acute: NO WQS
Note:n 5 9 Default C.V. Chronic:--— 2,080 7 No RP, Predicted Max<50%of Allowable Cw—
Limited data set No value>Allowable Cw Continue to monitor via LTMP
Acute: 269.9 No RP, Predicted Max<50%of Allowable Cw-
Nickel NC 88 FW(7QIOs) 261 ug/L 9 2 15.8 _ _ _ _ _ Continue to monitor via LTMP
Note:n<9 Default C.V. Chronic: 91.6 Tto RP, Predicted Max<50%of Allowable Cw-
Limited data set No value>Allowable Cw Continue to monitor via LTMP
Page 1 of 2 NCO026441 RPA,rpa
9/13/2013

Siler City WWTP REASONABLE POTENTIAL ANALYSIS Outfall 001
NCO026441 _ _ _Q_w_=_4_M_GD_
Acute: 57.9 Selenium NC 5 FW(7Q10s) 56 ug/L 8 0 16.7 No Detects No RP Continue to monitor via LTMP
__ _ _ _
Note:n59 Default C.V. Chronic:------ --- T---- '-------
Limited data se No value>Allowable Cw No Detects,No RP Continue to monitor via ITMP
Acute: 69.3 No RP,Predicted Max ?:50%of Allowable Cw-
Zinc(AL) NC 50 FW(7Q10s) 67 ug/L 56 48 68.9 _ apply Quarterly Monitoring
Chronic: 52.0 RR far Al(Gu; n,Ag,Fe,C1)-apply Quarterly
No value>Allowable Cw Monitoring in conjunction with.TQXTest
Chloroform C 170 HH(Qavg) µg/L 3 3 106.970 Acute: NO WQS_ _ ____
Note:n<_9 Default C.V. Chronic: 408.556 [No RP, Predicted Max<60✓0 of Allowable Cw-NoLimited data set No value>Allowable Cw onitoring required
Dichlorobromomethane C 17 HH(Qavg) µg/L 3 1 1 17.622 Acute: NO WQS_
Note:n<_9 Default C.V. Chronic: 40.856 No RP, Predicted Max<50%of Alfowatil6 Cw No
Limited data set No value>Allowable Cw Monitoring required
Page 2 of 2 NCO026441 RPA,rpa
9/13/2013

REASONABLE POTENTIAL ANALYSIS
Arsenic- FW Standard Arsenic-HHMS Standards i
COPY-
SECTION
Date Data BDL=1/2DL Results - Date Data BDL=112DL Results
1 Std Dev. 1.8516 1 Std Dev. 1.8516
2 Mean 4.0000 2 Mean 4.0000
3 Mar-1'1 ,; 10 5 C.V.(default) 0.6000 3 3/1/2011 < 10 5 C.V.(default) 0.6000
4 -' n 8 4 n 8
5 5
6 ;furl-11 Mult Factor= 3.33 6 Mult Factor= 3.33
7 Max.Value 5.0 ug/L 7 Max.Value 5.0 ug/L
8 Max.Pred Cw 16.7 ug/L 8 Max.Fred Cw 16.7 ug/L
9 Sep-11 110' 5 9 9/1/2011 < 10 5
10 10
11 11
12 Dec-11 2 1 12 1211/2011 < 2 1
13 13
14 14
15 Mar-12 2 1 15 3/1/2012 < 2 1
16 16
17 17
18 Jun-12 10 5 18 6/1/2012 < 10 5
19 19
20' 20
21 Sep-12 10 5 21 9/1/2012 < 10 5
22 22
23 23
24 Dec-12 10 5 24 12/1/2012 < 10 5
25 25
26 26
27 Mar-13 10 5 27 3/1/2013 < 10 5
28 28
29 29
30 30
31 31
32 32
33 33
34 34
35 35
36 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44' 44
45 45
46 46
47 47
48 48
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
2012 RPA-Freshwater b,data
1- 9/13/2013

REASONABLE POTENTIAL ANALYSIS
Cadmium SPECIAL. Chlorides(AL)
Values'MTH
•-
Date Data BDL=1/2DL Results •- Date Data BDL=1/2DL Results i
1 Std Dev. 1.4038 1 1J3/2011 134 0. 134 Std Dev. 40.7820
2 Mean 1.5722 2 1/1872011 187 0: 187 Mean 74.4
3 MFar-11 < 2 1 C.V.(default) 0.6000 3 21712011 66 0 66 C.V. 0.5484
4 n 9 4 212112011 115.0. 115 n 56
5 5 318/2011 93.8' 93.8
6 Jun-11 < 2i 1 Mult Factor= 3.16 6 3121/2011 1220 122 Mult Factor= 1.6
7 Max.Value 4.0 ug/L 7 414/2011 161 0 161 Max.Value 189.0
8 Max.Fred Cw 12.6 ug/L 8 411812011 164.0. 164 Max.Pred Cw 302.4
9 Sep-11 4' 4 9 5/5/2011 1,270 127
10 10 6/16/2011 1100 110
11 11 617/2011 124.0 124
12 Dec-1.1 < 0.15 0.075 12 6/20/2011 116.0 118
13 13 7/5/2011 132A 132
14 14 7/1812011 124 0= 124
15 Mar-12 < 0.15' 0.075 15 $11/2011 72:7 72.7
16 16 8/1512011 651' 65.1
17 17 9/13/2,011 75.5 75.5
18 Jun-12 ? 2 1 18 912612011 26:7 26.7
19 19 101'f0/2011 76;.3. 76.3
20 20 10124/2011 57.9 57.9
21 Sep-12 3 3 21 111712011 94.7 94.7
22 22 11/20/2011 63.1! 63.1
23 23 12/612011 61.0 61
24 Dec-12 <: 2 1 24 12/1912011 39 0 39
25 25 113/2012 37 9' 37.9
26 26 1/1712012 1690 189
27 Mar-13 3 3 27 21612412 103:0 103
28 28 2120/2012 54.11 54.1
29 29 3/13/2012 42.1'' 42.1
30 30 3/26/2012 36.2' 36.2
31' 31 419/2012 273i 27.3
32 32 4/23/2011 29.5' 29.5
33 33 517/2012 41.01 41
34 34 51,2112012 39A 39.1
35 35 615/2012 40.0 40
36 36 6118/2012 54.1 54.1
37 37 71212012 62.6 52.6
38 38 711 /20G2 57.9 57.9
39 39 81612012 55.2 55.2
40 40 812012012 631 63.1
41 41 9/1112012 .5T9 57.9
42 42 912412012 55.0' 55
43 43 10/812012 67.9 57.9
44 44 1Q/2212012 66,0 65
45 45 11/512012 6318 53.8
46 46 11/1912012 C 54A 54.1
47 47 124/20112 _i� 52.6' 52.6
48 48 Y2J1712012 :. 55.5' 55.5
49 49 1/712013 40.0 40
50 50 1122l2013 48.8 48.8
51 51 21412013 - 52.6 52.6
52 52 2/18/2012 43.1 43.1
53 53 3/1212013 44.2 44.2
54 54 3125/2013 54.1 54.1
55 " 55 418/201.3 .JI 36.0 36
56 56 412212013 61.16 61.6
57 57
2012 RPA-Freshwater b,data
-2- 9/13/2013

REASONABLE POTENTIAL ANALYSIS
Chromium Copper(AL)
i Date Data BDL=1/2DL Results s• Date Data BDL=1/2DL Results
1 mar-!I c 5 2.5 Std Dev. 0.0000 1 W2A11 „ 7.0 7 Std Dev. 5.0117
2 Jun-11 5 2.5 Mean 2.5000 2 1/18/,2011 70; 7 Mean 6.2143
3 Sep-11 5 2.5 C.V. 0.0000 3 Z7/2011 30 3 C.V. 0.8065
4 Dec-11 5 2.5 n 9 4 2121/2011 2.0 1 n 56
5 Mar-12 - 5 2.5 5 31812-011 2,0' 1
6 Jun-12 5 2.5 Mult Factor= 1.00 6 3121/2011 50. 5 Mult Factor= 1.91
mg/L 7 Seep-12 5 2.5 Max.Value 2.5 ug/L 7 41412011 2.0 1 Max.Value 37.0
mg/L 8 Dec>1.2 5 2.5 Max.Pred Cw 2.5 ug/L 8 4/18/2011 2.0 1 Max.Pred Cw 70.7
9 Mar 13 5 2.5 9 5/212011 13.0' 13
10 iy 10 5/16/2011 2.0: 1
11 11 617/20,11 2.0: 1
12 12 6/20/2011 7.0 7
13' 13 715=11 2.0- 1
14 14 711:812011 5.0: 5
15 15 81112011 8.0 8
16 16 8115/2011 8.0 8
17 17 9/13/2011 1 U 10
18 18 9/26/2011 5.0 5
19 19 10/1:0/2011 8.0' 6
20 20 10/24/2011 5.0 5
21 21 1117/2011 5.0 5
22 22 11120/201/ 6.0 6
23 23 12/61,2011 4.0 4
24 24 12/19/2011 6.0i 6
25 25 1/3/2012 5.0. 5
26 26 1/17/2012 7.0' 7
27 27 2/612012 4.0' 4
28' 28 2/20120112 9.0; 9
29'' 29 3/13/2012 4.0 4
30', 30 3/26/2012 3.0 3
31 31 4/9/2012 6.0 6
32 32 4/23/2012 4.0 4
33 33 5/7120 2 8.0 8
34 34 6/21/2012 5.01 5
35 35 6/012012 10 osi 5
36 36 6/10/2012 %0 5
37 37 7l212012 10,0' 5
38 38 7/1612012 10A 5
39 39 8/612012 10.0: 5
40 40 0/20/2012 10.0: 5
41 41 911112012 10.0 5
42 42 W24/2012 10.0' 10
43 43 10/8/2012 to.0 5
44' 44 10/22/2012 10.0 5
45 45 11/5/2012 11.0 11
46 46 1 Ill 9/201'2 37.0' 37
47 47 1214120/2 12.0 12
48 48 12117/20,12 8.0 8
49 49 1/712013 3.0: 3
50 50 1/2212013 8.0. 8
51 51 214412013 6.0' 6
52 52 2118/.2013 8.0- 8
53 53 3112/201.3 8.0 8
54 54 3/2512013 8.0: 8
55 55 418/2013 7.0 7
56 56 412212013 &0: 5
57 57
2012 RPA-Freshwater b,data
-3- 9/13/2013

REASONABLE POTENTIAL ANALYSIS y
Lead Mercury
--4 Values"WITH
Date Data BDL=1/2DL Results •- Date Data BDL=1/2DL Results
1 Mar-11 ` 10 5 Std Dev. 2.0946 1 Mar 11 1.4 1.4 Std Dev. 1.0198
2 Jun 11 +< 10 5 Mean 3.9444 2 Jun 11 It 1.2 1.2 Mean 1.5667
3 Sep-11 10 5 C.V.(default) 0.6000 3 Sep 11 4 1 0.5 C.V.(default) 0.6000
4 Dec-11 I• 05 0.25 n 9 4 Dec 11 ; 1.1 1.1 n 9
5 Mar12 ` � 0 5 0.25 5 Mar-12 14 1.4
6 Jun-12 ! 10 5 Mult Factor= 3.16 6 Jun-12 1.9 1.9 Mult Factor= 3.16
ug/L 7 Sep-12i 10 5 Max.Value 5.0 ug/L 7 Sep-12 1.1' 1.1 Max.Value 4.1
ug/L 8 Dec-12 10 5 Max.Pred Cw 15.8 ug/L 8 Dec,12 1.4 1.4 Max.Pred Cw 13.0
9 Mar--13 10 5 9 Mar-13 f 41, 4.1
10 r. 10 =n�
11 11
12 12
13 13
14' 14
15' 15
16' 16
17' 17
18 18
19 19
20 20
21 21
22 22
23 23
24, 24
25 25
26 26
27' 27
28 28
29 29
30 , 30
31 31
32 32
33 33
34 34
35 35
36 36'
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48. 48
49' 49
50, 50.
51 51'
52 52
53 53
54 54
55 55
56 56
57 57
2012 RPA-Freshwater b,data
-4- 9/13/2013

REASONABLE POTENTIAL ANALYSIS
Molybdenum Nickel
Date Data BDL=1/2DL Results •- Date Data BDL=1/2DL Results
1 Std Dev. 2.0632 1 Std Dev.
2 ,.� Mean 2.7778 2 Mean
3 Mar-11 ,�, 5 2.5 C.V.(default) 0.6000 3 Mat 14 1000, 5 C.V.(default)
4 �° n 9 4 n
6 jun-11 2 5 2.5 MultFactor= 3.16 6 Jum1 1o,00, 5 Mu It Factor=
ng/L 7 i Max.Value 8.0 ug/L 7 Max.Value
ng/L 8' ii Max.Pred Cw 25.3 ug/L 8 Max.Pred Cw
9 Sep-11 8 8 9 Sep-11 10.00 S
10 10
11 11
12 Dec-11 , 2 1 12 Dec=11 2.00: 2
13 - 13
14 14
15 Maf-12 2 1 15 Mar-12 3 00 3
16 16
17 17
18 Jurr12 5 2.5 18 Jm-12 10 00 5
19 19
20 20
21 Sep-12 5 2.5 21 Sep-12 10 00? 5
221 22
23' 23
24 Deo-12 5 2.5 24 Dec-12 10 00: 5
25 25
26 26
27 Mar-13 5 2.5 27 M 4.3 10.00' 5
28' 28
29' 29
30' 30
31 31
32 32
33 33
34 34
35 35
36' 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48 48
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
2012 RPA-Freshwater b,data
-5- 9/13/2013

REASONABLE POTENTIAL ANALYSIS
Selenium SPECIAL. Zinc(AL)
Vatues"WITH
•- Date Data BDL=1/2DL Results Date Data BDL=1/2DL Results
1.1304 1 Mar-11 10 5 Std Dev. 1.8516 1 1/ mll 16. 16 Std Dev.
4.4 444 2 Jun-11 a 10 5 Mean 4.0000 2 1/1812411 24- 24 Mean
0.6000 3 Sep-11 + 10 5 C.V.(default) 0.6000 3 2/712011 18- 18 C.V.
9 4 Dec-11 2 1 n 8 4 2/21/2011 24- 24 n
5 MarA2 2 1 5 $18/2011 13 13
3.16 6 Jun-12 10 5 Mult Factor= 3.33 6 312112011 31. 31 Mult Factor=
5.0 ug/L 7 Sep-12 C 10 5 Max.Value 5.0 ug/L 7 4/4/2011 23. 23 Max.Value
15.8 ug/L 8 Dec-12 K 10 5 Max.Pred Cw 16.7 ug/L 8 4/16/2011 24, 24 Max.Pred Cw
9 9 &W-2011 23 23
10 10 5116/2011 20 20
11 11 &712011 16- 16
12 12 6120/2011 < V 5
13 13 71612011 10. 10
14 14 7118/2011 < 10 5
15 15 811/2041 14 14
16 16 811512011 < 10, 5
17 17 9/1312011 40- 40
18 18 9/26/2011 7 7
19 19 10110/2011 12 12
20 20 104412011 9. 9
21 21 1IM2011 9. 9
22 22 11/20/2011 10. 10
23 23 12/6/2011 9 9
24 24 12119WI1 8. 8
25 25 1/312012 13. 13
26 26 1/1712012 1& 13
27 27 2/612012 16. 16
28 28 2/20/2012 20. 20
29 29 3113/2012 17. 17
30 30 3/26/2012 6. 6
31 31 4/9/2012 11. 11
32 32 4/23/3 2011 49 10. 5
33 33 6/7/2012 104 5
34 34 512112012 a 10. 5
35 35 6/512012 < 10. 5
36 36 6/18/2012 15. 15
37 37 71212012 < 10. 5
38 38 711612012 12. 12
39 39 8/612012 14. 14
40 40 8/20/2012 11. 11
41 41 5111/2012 12. 12
42 42 9124/2012 16. 16
43 43 10/812012 % 19
44 44 10/=2012 .25, 25
45 45 1V&2D12 28, 28
46 46 11119/2012 24. 24
47 47 124/2012 37. 37
48 48 1211712012 Q. 42
49 49 117/201'3 36. 36
50 50 1122/2013 266 26
51 51 21412013 ; 41,' 41
52 52 21181201,2 30. 30
53 53 3/12/2013 37. 37
54 54 3/25/2013 j 15. 19
55 55 418/2013 20. 20
56 56 4/2212013 27. 27
57 57
2012 RPA-Freshwater b,data
-6- 9/13/2013

REASONABLE POTENTIAL ANALYSIS
Chloroform Dichlorobromomet
- Date Data BDL=1/2DL Results 1111111111111M• Date Data BDL=1/2DL
10.3301 1 Jan.2007 179 17.9 Std Dev. 3.3650 1 Jan.2007 < 1 0.5
17.6250 2 Jun 2009 19 19 Mean 16.6333 2i Jun 2009 <, 1 0.5
0.5861 3 Mar2010 12.7. 12.7 C.V.(default) 0.6000 3' Mar2010 3.13` 3.13
56 4 n 3 4'
5 5
1.64 6 MultFactor= 5.63 6
42.0 ug/L 7 Max.Value 19,000000 Ug/L 7:
68.9 ug/L 8 Max.Pred Cw 106.970 Ng/L 8
9 gl
10 10
11 11
12 12'
13 13,
14 14
15 15
16
16
17 17
18 18
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
29 P9'
30 30
31 31'.
32 32.
33 33
34 34
35 35
36 36'
37 37.
38 38
39 39:
40
40 �
41 41
42 42
43 43
44
44'
45 46
46 46 1
47 47
48
48 _--�
49 49
50 50
51 51
52 52
53 53
54 54
55 55
56 56
57 57
2012 RPA-Freshwater b,data
-7- 9/13/2013

REASONABLE POTENTIAL ANALYSIS
hane 0
Results •- Date Data BDL=1/2DL Results r• Date Data
Sid Dev. 1.5184 1 Sid Dev. NO DATA 1
Mean 1,3767 2 Mean NO DATA 2
C.V.(default) 0.6 000 3 C.V. NO DATA 3
n 3 4 n 0 4
5 5'
Mult Factor= 5.63 6 Mu It Factor= N/A 6
Max.Value 3.130000 ug/L 7 Max.Value N/A 7
Max.Pred Cw 17,622 pg/L 8 Max.Pred Cw N/A 8
9 9
10 10
11, 11
12: 12
13 13
14i 14
15 15
16 16
17, 17
18' 18
19 19
20 20
21 21
22 22
23 23
24 24
25 25
26 26
27 27
28 28
29 29
30 30
31 31
32 32
33 33
34 34
35; 35
36 36
37 37
38 38
39 39
40 40
41 41
42 42
43 43
44 44
45 45
46 46
47 47
48. 48 I
49 49
50 5C
51 51
52 52
53 53
54. 54 1
55 55
56 56
57 57
2012 RPA-Freshwater b,data
-8- 9/13/2013

7/3/13 i
QS= ng/L MERCURY WQBEL/TBEL EVALUATION V:2013-5 ,
Facility Name:
Total Mercury 1631E PQL=0.5 ng/L 7Q10s= cfs WQBEL= 12.48 ng/L
Date Modifier Data Entry Value Permitted Flow= 47 ng/L
1.4
1.2
0.5
1.1 1.1 ng/L-Annual Average for 2011
1.4
1.9
1.1
1.4 1.5 ng/L-Annual Average for 2012
4.1 4.1 ng/L-Annual Average for 2013