NC0041696_Fact Sheet - with Addendum_20171003

Fact Sheet
NPDES Permit No. NCO041696
Permit Writer/Email Contact : Trupti Desai, trupti.desaigncdenr.gov
Date: 10/3/2017
Division/Branch: NC Division of Water Resources/NPDES Complex Permitting Unit
Fact Sheet Template: Version 09Jan2017
Permitting Action:
0 Renewal
❑ Renewal with Expansion
❑ New Discharge
❑ Modification (Fact Sheet should be tailored to mod request)
Note: A complete application should include the following:
• For New Dischargers, EPA Form 2A or 2D requirements, Engineering Alternatives Analysis, Fee
• For Existing Dischargers (POTV), EPA Form 2A, 3 effluent pollutant scans, 4 21 species WET tests.
• For Existing Dischargers (Non-POTW), EPA Form 2C with correct analytical requirements based on industry category.
Complete applicable sections below. If not applicable, enter NA.
1. Basic Facility Information
Facility Information
Applicant/Facility Name:
Town of Valdese/Lake Rhodhiss WWTP
Applicant Address:
P.O. Box 339, Valdese NC
Facility Address:
2100 Lake Rhodhiss Drive, Valdese NC
Permitted Flow:
Current — 3.5 MGD
Permitted — 7.5 MGD and 10.5 MGD (after Expansion)
Facility Type/Waste:
Major Municipal - Domestic and Industrial
Facility Class:
Class IV
Treatment Units:
Influent pump station, Bar screen, Grit removal, Primary clarifiers, Aeration
basins, Secondary clarifiers, Chlorination, Dechlorination, Gravity sludge,
Thickeners, Residual centrifuges, Residuals composting operation
Pretreatment Program
(Y/N)
Yes
County:
Burke
Region
Asheville (ARO)
Briefly describe the proposed permitting action and facility background: The Town of Valdese has requested
renewal of the NPDES permit for Lake Rhodhiss Wastewater Treatment Plant. The existing WWTP has
a design capacity of 7.5 MGD but currently is authorized to discharge 3.5 MGD to Lake Rhodhiss, a class
Page 1 of 16

WS -IV, B, CA waters. The class denotes use as a water supply, primary recreation and critical area
waterbody. The facility serves the Towns of Valdese, Drexel, and Rutherford College in addition to Burke
County for an estimated total of 8,200 persons treating both domestic and industrial wastewater. Lake
Rhodhiss was impaired for pH beginning with the 2006 303d list but was removed in 2014.
The permittee requested an additional effluent limitation and monitoring page for 3.5 MGD flow in the
previous permit renewal application in 2009 due to reduced industrial wastewater flow to the facility. The
current permit has tiered effluent pages for 3.5, 7.5 and 10.5 MGD flow. Average daily flow rates in
2012, 2013 and 2014 were 2.4 MGD, 2.5 MGD and 1.75 MGD respectively. The flow rate did not go
above 1.6 MGD in 2017 to date.
The treatment plant has a pretreatment program and a Long Term Monitoring Plan (LTMP) as it receives
flow from 9 noncategorical Significant Industrial Users (SIUs) and one Categorical Industrial User. The
permitted flow from the industrial users is 3.18 MGD but the average industrial flow in 2016 was 1.24
MGD. The facility will continue to implement its existing pretreatment program and monitor all
parameters as required.
2. Receiving Waterbody Information:
Receiving Waterbody Information
Outfalls/Receiving Stream(s):
Lake Rhodhiss
Stream Segment:
11—(37)
Stream Classification:
WS -IV, B, CA
Drainage Area (mi2):
705
Summer 7Q10 (cfs)
225.00 (Dam Release)
Winter 7Q 10 (cfs):
225.00 (Dam Release)
30Q2 (cfs):
225.00 (Dam Release)
Average Flow (cfs):
225.00 (Dam Release)
IWC (% effluent):
2.3% - 3.5 MGD (7Q10S)
4.8 % - 7.5 MGD (7Q10S)
6.6 % - 10.5 MGD (7Q1OS)
303(d) listed/parameter:
NA
Subject to TMDL/parameter:
Mercury Statewide TMDL approved in 2012
Subbasin/HUC:
03-08-31/03050101
State Grid / USGS Topo Quad:
D12SE/ Valdese, NC
3. Effluent Data Summary
Effluent data is summarized below for the period January, 2012 through April, 2017.
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Table. 1 Effluent Data Summary
Parameter
Units
Average
Max
Min
Permit Limit
Flow
MGD
1.9
8.8
0.29
3.5 MGD
7.5 MGD
10.5 MGD
BODS
mg/1
4.31
261
0.2
MA 30.0 mg/1
WA 45.0 mg/1
NH3N
mg/1
0.58
2.5
0.5
TSS
mg/1
13.69
1468
2.5
MA 30.0 mg/1
WA 45.0 mg/1
pH
SU
6.86
7.8
6.3
Between 6-9
Temperature
°C
17.47
23.0
12.0
DO
mg/1
7.61
15.8
15.8
DA> 5.0 mg/l
Fecal Coliform
(Geometric Mean)
#/100 ml
7.0
16.0
5.0
MA 200/100ml
WA 400/100ml
TRC
µg/1
28.55
63.0
2.0
DM 28 µg/1
TN
mg/1
7.38
49.6
1.58
TP
mg/1
1.46
15.0
0.25
Silver
µg/1
1.00
2.0
< 1
Selenium
µg/1
9.93
13.0
5.0
Arsenic
µg/1
9.75
<10
3.0
Cadmium
µg/1
0.61
11.0
< 0.2
Chloride
mg/1
249.78
434
111
Chromium
µg/1
4.32
21.0
< 1
Copper
µg/1
16.58
37.0
< 1
Cyanide
µg/1
6.0
2.0
< 5
Mercury
Ng/1
2.65
4.77
1.45
Molybdenum
µg/1
4.71
33.0
< 1
Nickel
µg/1
1.82
9.0
< 1
Lead
µg/1
11.57
59.0
< 5
Sulfate
mg/1
68.63
166.0
3.09
Phenol
mg/1
11.38
15.0
< 10
Zinc
µg/1
63.37
310
< 1
MA -Monthly Average, WA -Weekly Average, DM -Daily Maximum, DA -Daily Average
4. Instream Data Summary
Instream monitoring may be required in certain situations, for example: 1) to verify model predictions
when model results for instream DO are within 1 mg/1 of instream standard at full permitted flow; 2) to
verify model predictions for outfall diffuser; 3) to provide data for future TMDL; 4) based on other
instream concerns. Instream monitoring may be conducted by the Permittee, and there are also
Monitoring Coalitions established in several basins that conduct instream sampling for the Permittee (in
which case instream monitoring is waived in the permit as long as coalition membership is maintained).
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If applicable, summarize any instream data and what instream monitoring will be proposed for this
permit action: The current permit requires instream monitoring for dissolved oxygen and temperature.
Instream data from January, 2012 to April, 2017 were reviewed. There were no apparent differences in
the upstream and downstream dissolved oxygen concentration and temperature in the samples taken
during the same time period. The dissolved oxygen level in the stream was above 6.5 mg/1 during this
time period. As a major facility with industrial sources, instream monitoring for conductivity will be
added in conjunction with dissolved oxygen and temperature to this permit.
Is this facility a member of a Monitoring Coalition with waived instream monitoring (YIN): N
Name of Monitoring Coalition: NA
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years): The compliance data from
January, 2012 to April, 2017 was reviewed. The permittee received a total of 15 notice of violations for
exceeding limits for TSS and fecal coliform, and violating monitoring frequency of BOD and TKN. The
permittee violated TSS limits 8 times. There are 12 enforcement cases filed against the facility for
violating TSS and BOD weekly and monthly average effluent limits. The facility has paid $13664.64 in
fines during this period. The ARO is working with the facility to monitor the facility's compliance
performance.
Summarize the compliance record with aquatic toxicity test limits and any second species test results
(past 5 years): The facility passed 20 of 20 quarterly chronic toxicity tests as well as all 4 second species
chronic toxicity tests. The facility passed all four second species toxicity tests at the effluent
concentration above 9.2%.
Summarize the results from the most recent compliance inspection: One compliance inspection was
conducted in March, 2015. The facility was found well maintained and operated during this inspection.
6. Water Quality -Based Effluent Limitations (WQBELs)
Dilution and Mixing Zones
In accordance with 15A NCAC 213.0206, the following streamflows are used for dilution considerations
for development of WQBELs: 1 Q 10 streamflow (acute Aquatic Life); 7Q 10 streamflow (chronic Aquatic
Life; non -carcinogen HH); 30Q2 streamflow (aesthetics); annual average flow (carcinogen, HH).
If applicable, describe any other dilution factors considered (e.g., based on CORMIX model results): NA
If applicable, describe any mixing zones established in accordance with 15A NCAC 2B. 0204(b): NA
Oxygen -Consuming Waste Limitations
Limitations for oxygen -consuming waste (e.g., BOD) are generally based on water quality modeling to
ensure protection of the instream dissolved oxygen (DO) water quality standard. Secondary TBEL limits
(e.g., BOD= 30 mg/1 for Municipals) may be appropriate if deemed more stringent based on dilution and
model results.
If permit limits are more stringent than TBELs, describe how limits were developed: Effluent BOD limits
after facility expansion to 10.5 MGD are stringent than TBELs. These limits are based on speculative
limits given to the facility in 1998 using the Best Professional Judgement (BPJ).
Page 4 of 16

Ammonia and Total Residual Chlorine Limitations
Limitations for ammonia are based on protection of aquatic life utilizing an ammonia chronic criterion of
1.0 mg/l (summer) and 1.8 mg/l (winter). Acute ammonia limits are derived from chronic criteria,
utilizing a multiplication factor of 3 for Municipals and a multiplication factor of 5 for Non -Municipals.
Limitations for Total Residual Chlorine (TRC) are based on the NC water quality standard for protection
of aquatic life (17 ug/1) and capped at 28 ug/l (acute impacts). Due to analytical issues, all TRC values
reported below 50 ug/l are considered compliant with their permit limit.
Describe any proposed changes to ammonia and/or TRC limits for this permit renewal: Ammonia
nitrogen monitoring for 3.5 MGD and Ammonia nitrogen limits for 10.5 MGD flow will remain the same.
New ammonia nitrogen limits based on waste allocation calculations for receiving body are proposed for
7.5 MGD flow rate. No changes in TRC limits are proposed.
Reasonable Potential Analysis (RPA) for Toxicants
If applicable, conduct RPA analysis and complete information below.
The need for toxicant limits is based upon a demonstration of reasonable potential to exceed water quality
standards, a statistical evaluation that is conducted during every permit renewal utilizing the most recent
effluent data for each outfall. The RPA is conducted in accordance with 40 CFR 122.44 (d) (i). The NC
RPA procedure utilizes the following: 1) 95% Confidence Level/95% Probability; 2) assumption of zero
background; 3) use of 1/2 detection limit for "less than" values; and 4) streamflows used for dilution
consideration based on 15A NCAC 2B.0206. Effejctive April 6, 2016, NC began implementation of
dissolved metals criteria in the RPA process in accordance with guidance titled NPDES Implementation of
Instream Dissolved Metals Standards, dated June 10, 2016.
Three reasonable potential analyses were conducted for permitted flows of 3.5 MGD, 7.5 MGD and 10.5
MGD using the effluent toxicant data collected between September, 2013 and April, 2017. Pollutants of
concern included toxicants with positive detections and defined water quality standards/EPA criteria.
Based on these analyses, the following permitting actions are proposed for this permit:
• Effluent Limit with Monitoring. The following parameters will receive a water quality -based
effluent limit (WQBEL) since they demonstrated a reasonable potential to exceed applicable
water quality standards/criteria: None for all three permitted flows
• Monitoring Only. The following parameters will receive a monitor -only requirement since they
did not demonstrate reasonable potential to exceed applicable water quality standards/criteria,
but the maximum predicted concentration was >50% of the allowable concentration: None for
all three permitted flows
• No Limit or Monitoring: The following parameters will not receive a limit or monitoring, since
they did not demonstrate reasonable potential to exceed applicable water quality
standards/criteria and the maximum predicted concentration was <50% of the allowable
concentration: Arsenic, Cadmium, Chlorides, Chromium, Copper, Cyanide, Lead,
Molybdenum, Nickel, Selenium, Silver, Sulfates, Zinc and Total Phenolic Compounds. These
compounds will be monitored in pretreatment program during this permit cycle.
• POTW Effluent Pollutant Scan Review: Three effluent pollutant scans were evaluated for
additional pollutants of concern.
o The following parameter(s) will receive a water quality -based effluent limit (WQBEL)
with monitoring, since as part of a limited data set, two samples exceeded the allowable
discharge concentration: None
Page 5 of 16

o The following parameter(s) will receive a monitor -only requirement, since as part of a
limited data set, one sample exceeded the allowable discharge concentration: None
If applicable, attach a spreadsheet of the RPA results as well as a copy of the Dissolved Metals
Implementation Fact Sheet for freshwater/saltwater to this Fact Sheet. Include a printout of the RPA
Dissolved to Total Metal Calculator sheet if this is a Municipality with a Pretreatment Program.:
Attached both Documents.
Toxicity Testing Limitations
Permit limits and monitoring requirements for Whole Effluent Toxicity (WET) have been established in
accordance with Division guidance (per WET Memo, 8/2/1999). Per WET guidance, all NPDES permits
issued to Major facilities or any facility discharging "complex" wastewater (contains anything other than
domestic waste) will contain appropriate WET limits and monitoring requirements, with several
exceptions. The State has received prior EPA approval to use an Alternative WET Test Procedure in
NPDES permits, using single concentration screening tests, with multiple dilution follow-up upon a test
failure.
Describe proposed toxicity test requirement: This is a major POTW, and a quarterly chronic WET limit
at 2.4% effluent concentration using Ceriodaphnia dubia was required during previous permit period.
These requirements will continue in this permit. For 7.5 MGD and 10.5 MGD flows, a quarterly chronic
WET limit at 4.9 % and 6.7 % effluent concentration using Ceriodaphnia dubia will be required
respectively.
Mercury Statewide TMDL Evaluation
There is a statewide TMDL for mercury approved by EPA in 2012. The TMDL target was to comply
with EPA's mercury fish tissue criteria (0.3 mg/kg) for human health protection. The TMDL established a
wasteload allocation for point sources of 37 kg/year (81 lb/year), and is applicable to municipals and
industrial facilities with known mercury discharges. Given the small contribution of mercury from point
sources (-2% of total load), the TMDL emphasizes mercury minimization plans (MMPs) for point source
control. Municipal facilities > 2 MGD and discharging quantifiable levels of mercury (>1 ng/1) will
receive an MMP requirement. Industrials are evaluated on a case-by-case basis, depending if mercury is a
pollutant of concern. Effluent limits may also be added if annual average effluent concentrations exceed
the WQBEL value (based on the NC WQS of 12 ng/1) and/or if any individual value exceeds a TBEL
value of 47 ng/l.
Table.2 Mercury Effluent Data Summary — 3.5 MGD
Page 6 of 16
2011 2013 2014 2015
2016
2017
# of Samples
1 1 1 1
2
2
Annual Average Conc. n /L
1.7 2.6 1.9 4.7
1.8
3.4
Maximum Conc., n L
1.72 2.55 1.9 4.69
2.08
4.77
TBEL, n /L
47
W BEL, n /L
517.9
Page 6 of 16

Table.3 Mercury Effluent Data Summary - 7.5 MGD
Table.4 Mercury Effluent Data Summary - 10.5 MGD
2011
2013
2014 2015
2016
2017
# of Samples
1
1
1 1
2
2
Annual Average Conc. ng/L
1.7
2.6
1.9 4.7
1.8
3.4
Maximum Conc., ng/L
1.72
2.55
1.9 4.69
2.08
4.77
TBEL, ng/L
47
WQBEL, ng/L
248.1
Table.4 Mercury Effluent Data Summary - 10.5 MGD
Describe proposed permit actions based on mercury evaluation: Majority of the mercury data reported
on DMRs were not measured using EPA method 1631E. The permittee was informed to use the method
1631E on all future analyses.
Based on the mercury evaluation results that were available and did use method 1631E, no annual
average mercury concentration exceeded the WQBEL, and no individual mercury sample exceeded the
TBEL, in this case no mercury limit is required. However, since the facility is >2 MGD and reported
quantifiable levels of mercury (> 1 ng/1), a mercury minimization plan (MMP) has been added to this
permit.
Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TMDLs/Nutrient Management Strategies and their implementation
within this permit: Lake Rhodhiss was listed in303d list for high pH beginning in 2006 which indicated
high algal growth in the lake. Based on this impairment, a Lake Rhodhiss Management Strategy was
developed for point and non point sources in 2010. During previous permit cycle, nutrient monitoring
and mass load limits were proposed based on this strategy. Lake Rhodhiss was removed from 303d list in
2014 as it was no longer impaired for pH. Due to lower pH and algal growth in the lake, the Division
decided to change nutrient monitoring frequencies from weekly to monthly and eliminate instream
monitoring requirements for four facilities (Marion, Morganton, Lenoir and Valdese) discharging to Lake
Rhodhiss. This permit reflects these changes in nutrient monitoring for 3.5 MGD, 7.5 MGD and 10.5
MGD flows. The nutrient mass load limits for 10.5 MGD flow after expansion of the facility will remain
the same during this permit period.
Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: N/A
If applicable, describe any compliance schedules proposed for this permit renewal in accordance with
15A NCAC 2K 0107(c) (2) (B), 40CFR 122.4 7, and EPA May 2007 Memo: NA
If applicable, describe any water quality standards variances proposed in accordance with NCGS 143-
215.3(e) and 15A NCAC 2B. 0226 for this permit renewal: NA
Page 7 of 16
2011
2013
2014 2015
2016
2017
# of Samples
1
1
1 1
2
2
Annual Average Conc. ng/L
1.7
2.6
1.9 4.7
1.8
3.4
Maximum Conc., ng/L
1.72
2.55
1.9 4.69
2.08
4.77
TBEL, ng/L
47
WQBEL, ng/L
180.6
Describe proposed permit actions based on mercury evaluation: Majority of the mercury data reported
on DMRs were not measured using EPA method 1631E. The permittee was informed to use the method
1631E on all future analyses.
Based on the mercury evaluation results that were available and did use method 1631E, no annual
average mercury concentration exceeded the WQBEL, and no individual mercury sample exceeded the
TBEL, in this case no mercury limit is required. However, since the facility is >2 MGD and reported
quantifiable levels of mercury (> 1 ng/1), a mercury minimization plan (MMP) has been added to this
permit.
Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TMDLs/Nutrient Management Strategies and their implementation
within this permit: Lake Rhodhiss was listed in303d list for high pH beginning in 2006 which indicated
high algal growth in the lake. Based on this impairment, a Lake Rhodhiss Management Strategy was
developed for point and non point sources in 2010. During previous permit cycle, nutrient monitoring
and mass load limits were proposed based on this strategy. Lake Rhodhiss was removed from 303d list in
2014 as it was no longer impaired for pH. Due to lower pH and algal growth in the lake, the Division
decided to change nutrient monitoring frequencies from weekly to monthly and eliminate instream
monitoring requirements for four facilities (Marion, Morganton, Lenoir and Valdese) discharging to Lake
Rhodhiss. This permit reflects these changes in nutrient monitoring for 3.5 MGD, 7.5 MGD and 10.5
MGD flows. The nutrient mass load limits for 10.5 MGD flow after expansion of the facility will remain
the same during this permit period.
Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: N/A
If applicable, describe any compliance schedules proposed for this permit renewal in accordance with
15A NCAC 2K 0107(c) (2) (B), 40CFR 122.4 7, and EPA May 2007 Memo: NA
If applicable, describe any water quality standards variances proposed in accordance with NCGS 143-
215.3(e) and 15A NCAC 2B. 0226 for this permit renewal: NA
Page 7 of 16

7. Technology -Based Effluent Limitations (TBELs)
Municipals (if not applicable, delete and skip to Industrials)
Are concentration limits in the permit at least as stringent as secondary treatment requirements (30 mg/l
BODS/TSS for Monthly Average, and 45 mg/l for BODS/TSS for Weekly Average). YES
If NO, provide a justification for alternative limitations (e.g., waste stabilization pond). NA
Are 85% removal requirements for BODS/TSS included in the permit? YES
If NO, provide a justification (e.g., waste stabilization pond). NA
If any limits are based on best professional judgement (BPJ), describe development: NA
Document any TBELs that are more stringent than WQBELs: NA
Document any TBELs that are less stringent than previous permit: NA
8. Antidegradation Review (New/Expanding Discharge):
The objective of an antidegradation review is to ensure that a new or increased pollutant loading will not
degrade water quality. Permitting actions for new or expanding discharges require an antidegradation
review in accordance with 15A NCAC 213.0201. Each applicant for a new/expanding NPDES permit
must document an effort to consider non -discharge alternatives per 15A NCAC 2H.0105( c)(2). In all
cases, existing instream water uses and the level of water quality necessary to protect the existing use is
maintained and protected.
If applicable, describe the results of the antidegradation review, including the Engineering Alternatives
Analysis (EAA) and any water quality modeling results: NA
9. Antibacksliding Review
Sections 402(0)(2) and 303(d)(4) of the CWA and federal regulations at 40 CFR 122.44(1) prohibit
backsliding of effluent limitations in NPDES permits. These provisions require effluent limitations in a
reissued permit to be as stringent as those in the previous permit, with some exceptions where limitations
may be relaxed (e.g., based on new information, increases in production may warrant less stringent TBEL
limits, or WQBELs may be less stringent based on updated RPA or dilution).
Are any effluent limitations less stringent than previous permit (YES/NO): NO
If YES, confirm that antibacksliding provisions are not violated: NA
10. Monitoring Requirements
Monitoring frequencies for NPDES permitting are established in accordance with the following
regulations and guidance: 1) State Regulation for Surface Water Monitoring, 15A NCAC 2B.0500; 2)
NPDES Guidance, Monitoring Frequency for Toxic Substances (7/15/2010 Memo); 3) NPDES Guidance,
Reduced Monitoring Frequencies for Facilities with Superior Compliance (10/22/2012 Memo); 4) Best
Professional Judgement (BPJ). Per US EPA (Interim Guidance, 1996), monitoring requirements are not
Page 8 of 16

considered effluent limitations under Section 402(0) of the Clean Water Act, and therefore anti -
backsliding prohibitions would not be triggered by reductions in monitoring frequencies.
For instream monitoring, refer to Section 4
11. Electronic Reporting Requirements
The US EPA NPDES Electronic Reporting Rule was finalized on December 21, 2015. Effective
December 21, 2016, NPDES regulated facilities are required to submit Discharge Monitoring Reports
(DMRs) electronically. Effective December 21, 2020, NPDES regulated facilities will be required to
submit additional NPDES reports electronically. This permit contains the requirements for electronic
reporting, consistent with Federal requirements.
12. Summary of Proposed Permitting Actions:
Table.5 Current Permit Conditions and Proposed Changes for 3.5 MGD, 7.5 MGD and 10.5 MGD
Parameter
Current Permit
Proposed Change
Basis for Condition/Change
Flow
MA 3.5 MGD, 7.5
No change
15A NCAC 2B.0505
MGD and 10.5 MGD
Total Monthly Flow
No requirements
Added monitoring
Required to calculate monthly nutrient
(TMF)
requirements for 10.5
loads
MGD flow
BODS
3.5 and 7.5 MGD
No change for all
TBEL. Secondary treatment
MA 30.0 mg/1
flows
standards/40 CFR 133/15A NCAC
WA 45.0 mg/1
2B.0406
10.5 MGD
MA 15.0 mg/1
WQBEL. Based on speculative limits
WA 22.5 mg/1
of 1998 calculated using BPJ
TSS
MA 30 mg/1
No change, apply to
TBEL. Secondary treatment
WA 45 mg/1
all flows
standards/40 CFR 133 / 15A NCAC
2B .0406
NH3-N
3.5 and 7.5 MGD
Monitoring frequency
WQBEL based on WLA calculations
Monitoring only
changed for all
for 3.5 and 7.5 MGD
10.5 MGD
permitted flows
Limits for 10.5 MGD flow are based
MA 4.0 mg/l
Added limits for 7.5
on speculative limits of 2008
WA 12.0 mg/1
MGD flow
calculated using BPJ
DO
Effluent and instream
Added daily average
WQBEL. State WQ standard, 15A
monitoring only
limit for all flows
NCAC 2B .0200, 15A NCAC
No change in instream
2B.0500
monitoring
Fecal coliform
MA 200 /100ml
No change, apply to
WQBEL. State WQ standard, 15A
(Geometric Mean)
WA 400 /100ml
all flows
NCAC 2B.0200
pH
Between 6 - 9 SU
No change, apply to
WQBEL. State WQ standard, 15A
all flows
NCAC 2B.0200
Page 9 of 16

Parameter
Current Permit
Proposed Change
Basis for Condition/Change
Temperature °C
Instream monitoring
Added effluent
15A NCAC 2B.0200 and 15A NCAC
only
monitoring for all
213.0500
flows
No change in instream
monitoring
Conductivity
No Requirements
Add effluent and
The facility has industrial dischargers
instream monitoring
and pretreatment program
for all flows
15A NCAC 2B.0500
Total Residual
DM 28.0 µg/l
No change for all
WQBEL. Maximum daily limit to
Chlorine
flows
protect acute toxicity
Total Nitrogen
3.5 MGD and 7.5 MGD
Monitoring frequency
Lake Rhodhiss was delisted from 303d
Weekly monitoring
reduced to monthly for
list.
10.5 MGD
all flows, No change
WQBEL for 10.5 MGD. Mass load
Monitoring with
in mass limit for 10.5
limits were calculated in 2009 based
mass limit of 146,659
MGD
on the Point Source Action Plan and
lb/yr
EPA recommendations
TKN and Nitrate
Weekly effluent
Frequency of
Lake Rhodhiss was delisted from 303d
Nitrogen
monitoring for 10.5
monitoring reduced to
list.
MGD
monthly for 10.5
MGD flow
Total Phosphorus
3.5 MGD and 7.5 MGD
Monitoring frequency
Lake Rhodhiss was delisted from 303d
Weekly monitoring
reduced to monthly for
list.
10.5 MGD
all flows, No change
WQBEL for 10.5 MGD. Mass load
Monitoring with
in mass limit for 10.5
limits were calculated in 2009 based
mass limit of 33,200
MGD
on the Point Source Action Plan and
lb/yr
EPA recommendations
Hardness - Total as
No requirements
Add quarterly
Adopted new 2016 water quality
[CaCO3 or Ca+Mg)]
monitoring of effluent
standards and EPA's guidelines on
and upstream hardness
hardness dependent metals
Total Copper
3.5 MGD
Removed monitoring
RPA results and EPA's guidance on
No requirements
hardness dependent metals
7.5 MGD and 10.5
MGD
Quarterly Monitoring
Total Selenium
3.5 MGD and 7.5 MGD
Removed limits and
RPA results and EPA's guidance on
Quarterly Monitoring
monitoring for all
hardness dependent metals
10.5 MGD
flows
MA 75.0 µg/1
DM 75.0 µg/1
Total Silver
Quarterly Monitoring
Removed monitoring
RPA results and EPA's guidance on
for all flows
hardness dependent metals
Toxicity Test
Chronic limit, 3.5%
No change all flows
WQBEL. No toxics in toxic amounts.
effluent for 3.5 MGD,
15A NCAC 2B.0200 and 15A NCAC
4.8% for 7.5 MGD and
2B.0500
6.6% for 10.5 MGD
Page 10 of 16

Parameter
Current Permit
Proposed Change
Basis for Condition/Change
Effluent Pollutant
Annual
3 times during a
40 CFR 122
Scan
permit period
Mercury
No requirement
Add MMP Special
Consistent with EPA approved 2012
Minimization Plan
Condition for all flows
Statewide Mercury TMDL
(MMP)
Implementation.
Electronic
No requirement
Add Electronic
In accordance with Electronic
Reporting
Reporting Special
Reporting Rule 2015.
Condition
MGD — Million gallons per day, MA - Monthly Average, WA — Weekly Average, DM — Daily Max
13. Fact Sheet Addendum (if applicable):
Were there any changes made since the Draft Permit was public noticed (Yes/No): NO
If Yes, list changes and their basis below: NA
The Division received a request from EPA to provide information on Lake Rhodhiss WWTP's outfall
configuration and flow rates/dilution used to calculate allowable concentration of various parameters of
concern in RPA. The outfall configuration with maps and geographical coordinates provided by the
permittee were submitted to the EPA. An additional set of RPAs was performed using 50% dilution i.e.
112.5 cfs in Lake Rhodhiss. The results of this RPA showed that the facility does not require any
toxicant limitations in the permit at 50% dilution.
The permittee submitted comments on the draft permit on 28 November, 2017. The public comment
period on the draft permit was ended on November 10. The permittee commented on:
1. Monitoring Requirements for Ammonia Nitrogen — The permittee opposed increased monitoring
requirements at 3.5 MGD and 7.5 MGD permitted flow and limitations at 7.5 MGD permitted
flow based on plant's past performance and compliance record and requested to remove these
limitation and monitoring requirements or change the monitoring frequency to weekly from daily.
2. Instream Monitoring - The permittee requested to remove upstream and downstream monitoring
requirements.
3. Mercury Minimization Plan — The permitted requested to remove the requirements for Mercury
Minimization Plan from the permit.
4. Misc. - One typographical error in the cover letter for the draft permit.
Instream monitoring requirements were discussed with the permittee before issuing the draft permit. The
Division denied to remove these requirements according to 15A. NCAC 0213.508. The Division can not
remove limitations and monitoring requirements for Ammonia Nitrogen and Mercury Minimization Plan
from the proposed NPDES permit the explanation is added to the cover letter for the final permit. The
typographical error has been corrected in the final permit cover letter.
14. Fact Sheet Attachments (if applicable):
RPA Spreadsheet Summary
Dissolved Metals Implementation/Freshwater or Saltwater
Mercury TMDL Evaluation
Page 11 of 16

• Additional RPA Spreadsheets (112.5 cfs)
15. Proposed Schedule for Permit Issuance
Draft Permit to Public Notice : 10/3/2017
Permit Scheduled to Issue (Tentative): 11/27/2017
Page 12 of 16

NPDES Implementation of Instream Dissolved Metals Standards - Freshwater Standards
The NC 2007-2015 Water Quality Standard (WQS) Triennial Review was approved by the NC
Environmental Management Commission (EMC) on November 13, 2014. The US EPA subsequently
approved the WQS revisions on April 6, 2016, with some exceptions. Therefore, metal limits in draft
permits out to public notice after April 6, 2016 must be calculated to protect the new standards - as
approved.
Table 1. NC Dissolved Metals Water Q ality Standards/A uatic Life Protection
Parameter
Acute FW, gg/l
(Dissolved)
Chronic FW, gg/l
(Dissolved)
Acute SW, gg/l
(Dissolved)
Chronic SW, gg/l
(Dissolved)
Arsenic
340
150
69
36
Beryllium
65
6.5
---
---
Cadmium
Calculation
Calculation
40
8.8
Chromium III
Calculation
Calculation
---
---
Chromium VI
16
11
1100
50
Copper
Calculation
Calculation
4.8
3.1
Lead
Calculation
Calculation
210
8.1
Nickel
Calculation
Calculation
74
8.2
Silver
Calculation
0.06
1.9
0.1
Zinc
Calculation
Calculation
90
81
Table 1 Notes:
1. FW= Freshwater, SW= Saltwater
2. Calculation = Hardness dependent standard
3. Only the aquatic life standards listed above are expressed in dissolved form. Aquatic life
standards for Mercury and selenium are still expressed as Total Recoverable Metals due to
bioaccumulative concerns (as are all human health standards for all metals). It is still necessary
to evaluate total recoverable aquatic life and human health standards listed in 15A NCAC
213.0200 (e.g., arsenic at 10 µg/1 for human health protection; cyanide at 5 gg/L and fluoride at
1.8 mg/L for aquatic life protection).
Table 2. Dissolved Freshwater Standards for Hardness -Dependent Metals
The Water Effects Ratio (WER) is equal to one unless determined otherwise under 15A
NCAC 02B .0211 Subparagraph (11)(d)
Metal
NC Dissolved Standard, gg/1
Cadmium, Acute
WER*{1.136672-[ln hardness] (0.041838)} e^{0.9151 [ln hardness] -3.1485}
Cadmium, Acute Trout waters
WER*{1.136672-[ln hardness] (0.041838)} e^{0.9151[ln hardness] -3.6236}
Cadmium, Chronic
WER*{1.101672-[ln hardness] (0.041838)} e^{0.7998[ln hardness] -4.4451}
Chromium III, Acute
WER*0.316 e^{0.8190[ln hardness]+3.7256}
Chromium III, Chronic
WER*0.860 e^{0.8190[ln hardness]+0.6848}
Copper, Acute
WER*0.960 e^{0.9422[ln hardness] -1.700}
Copper, Chronic
WER*0.960 e^{0.8545[ln hardness] -1.702}
Lead, Acute
WER*{1.46203-[In hardness] (0.145712)} • eAll .273[ln hardness] -1.460)
Lead, Chronic
WER*{1.46203-[ln hardness](0.145712)} • eAll .273[ln hardness] -4.705)
Nickel, Acute
WER*0.998 • eAl0.8460[ln hardness]+2.255}
Nickel, Chronic
WER*0.997 • eAl0.8460[ln hardness]+0.0584}
Page 13 of 16

Silver, Acute
WER*0.85 • e^0.72[1n hardness] -6.59}
Silver, Chronic
Not applicable
Zinc, Acute
WER*0.978 e^{0.8473[ln hardness]+0.884}
Zinc, Chronic
WER*0.986 e^{0.8473[ln hardness]+0.884}
General Information on the Reasonable Potential Analysis (RPA)
The RPA process itself did not change as the result of the new metals standards. However, application of
the dissolved and hardness -dependent standards requires additional consideration in order to establish the
numeric standard for each metal of concern of each individual discharge.
The hardness -based standards require some knowledge of the effluent and instream (upstream) hardness
and so must be calculated case-by-case for each discharge.
Metals limits must be expressed as `total recoverable' metals in accordance with 40 CFR 122.45(c). The
discharge -specific standards must be converted to the equivalent total values for use in the RPA
calculations. We will generally rely on default translator values developed for each metal (more on that
below), but it is also possible to consider case -specific translators developed in accordance with
established methodology.
RPA Permittin! Guidance/WOBELs for Hardness -Dependent Metals - Freshwater
The RPA is designed to predict the maximum likely effluent concentrations for each metal of concern,
based on recent effluent data, and calculate the allowable effluent concentrations, based on applicable
standards and the critical low -flow values for the receiving stream.
If the maximum predicted value is greater than the maximum allowed value (chronic or acute), the
discharge has reasonable potential to exceed the standard, which warrants a permit limit in most cases. If
monitoring for a particular pollutant indicates that the pollutant is not present (i.e. consistently below
detection level), then the Division may remove the monitoring requirement in the reissued permit.
1. To perform a RPA on the Freshwater hardness -dependent metals the Permit Writer compiles the
following information:
• Critical low flow of the receiving stream, 7Q10 (the spreadsheet automatically calculates
the 1 Q 10 using the formula 1 Q 10 = 0.843 (s7Q 10, cfs) 0.993
• Effluent hardness and upstream hardness, site-specific data is preferred
• Permitted flow
• Receiving stream classification
2. In order to establish the numeric standard for each hardness -dependent metal of concern and for
each individual discharge, the Permit Writer must first determine what effluent and instream
(upstream) hardness values to use in the equations.
The permit writer reviews DMR's, Effluent Pollutant Scans, and Toxicity Test results for any
hardness data and contacts the Permittee to see if any additional data is available for instream
hardness values, upstream of the discharge.
If no hardness data is available, the permit writer may choose to do an initial evaluation using a
default hardness of 25 mg/L (CaCO3 or (Ca + Mg)). Minimum and maximum limits on the
hardness value used for water quality calculations are 25 mg/L and 400 mg/L, respectively.
Page 14 of 16

If the use of a default hardness value results in a hardness -dependent metal showing reasonable
potential, the permit writer contacts the Permittee and requests 5 site-specific effluent and
upstream hardness samples over a period of one week. The RPA is rerun using the new data.
The overall hardness value used in the water quality calculations is calculated as follows:
Combined Hardness (chronic)
_ (Permitted Flow, cfs *Avg. Effluent Hardness, mg/L) x (s7Q10, cfs *Avg. Upstream Hardness, mg/L)
(Permitted Flow, cfs + s7Q10, cfs)
The Combined Hardness for acute is the same but the calculation uses the 1 Q 10 flow.
3. The permit writer converts the numeric standard for each metal of concern to a total recoverable
metal, using the EPA Default Partition Coefficients (DPCs) or site-specific translators, if any
have been developed using federally approved methodology.
EPA default partition coefficients or the "Fraction Dissolved" converts the value for
dissolved metal at laboratory conditions to total recoverable metal at in -stream
ambient conditions. This factor is calculated using the linear partition coefficients
found in The Metals Translator: Guidance for Calculating a Total Recoverable
Permit Limit from a Dissolved Criterion (EPA 823-B-96-007, June 1996) and the
equation:
Cdiss - I
Ctotal 1 + { [Kp.] [SS(l+a)] [10-6] }
Where:
ss = in -stream suspended solids concentration [mg/1], minimum of 10 mg/L used,
and
Kpo and a = constants that express the equilibrium relationship between dissolved
and adsorbed forms of metals. A list of constants used for each hardness -dependent
metal can also be found in the RPA program under a sheet labeled DPCs.
4. The numeric standard for each metal of concern is divided by the default partition coefficient (or
site-specific translator) to obtain a Total Recoverable Metal at ambient conditions.
In some cases, where an EPA default partition coefficient translator does not exist (ie. silver), the
dissolved numeric standard for each metal of concern is divided by the EPA conversion factor to
obtain a Total Recoverable Metal at ambient conditions. This method presumes that the metal is
dissolved to the same extent as it was during EPA's criteria development for metals. For more
information on conversion factors see the June, 1996 EPA Translator Guidance Document.
5. The RPA spreadsheet uses a mass balance equation to determine the total allowable concentration
(permit limits) for each pollutant using the following equation:
Ca = (s7Q 10 + Qw) (Cwgs) — (s7Q 10) (Cb)
Qw
Where: Ca = allowable effluent concentration (µg/L or mg/L)
Cwqs = NC Water Quality Standard or federal criteria (ttg/L or mg/L)
Cb = background concentration: assume zero for all toxicants except NH3* (gg/L or mg/L)
Qw = permitted effluent flow (cfs, match s7Q10)
Page 15 of 16

s7Q 10 = summer low flow used to protect aquatic life from chronic toxicity and human
health through the consumption of water, fish, and shellfish from noncarcinogens (cfs)
* Discussions are on-going with EPA on how best to address background concentrations
Flows other than s7Q10 may be incorporated as applicable:
IQ 10 = used in the equation to protect aquatic life from acute toxicity
QA = used in the equation to protect human health through the consumption of water,
fish, and shellfish from carcinogens
30Q2 = used in the equation to protect aesthetic quality
6. The permit writer enters the most recent 2-3 years of effluent data for each pollutant of concern.
Data entered must have been taken within four and one-half years prior to the date of the permit
application (40 CFR 122.21). The RPA spreadsheet estimates the 95th percentile upper
concentration of each pollutant. The Predicted Max concentrations are compared to the Total
allowable concentrations to determine if a permit limit is necessary. If the predicted max exceeds
the acute or chronic Total allowable concentrations, the discharge is considered to show
reasonable potential to violate the water quality standard, and a permit limit (Total allowable
concentration) is included in the permit in accordance with the U.S. EPA Technical Support
Document for Water Quality -Based Toxics Control published in 1991.
7. When appropriate, permit writers develop facility specific compliance schedules in accordance
with the EPA Headquarters Memo dated May 10, 2007 from James Hanlon to Alexis Strauss on
40 CFR 122.47 Compliance Schedule Requirements.
The Total Chromium NC WQS was removed and replaced with trivalent chromium and
hexavalent chromium Water Quality Standards. As a cost savings measure, total chromium data
results may be used as a conservative surrogate in cases where there are no analytical results
based on chromium III or VI. In these cases, the projected maximum concentration (95th %) for
total chromium will be compared against water quality standards for chromium III and
chromium VI.
9. Effluent hardness sampling and instream hardness sampling, upstream of the discharge, are
inserted into all permits with facilities monitoring for hardness -dependent metals to ensure the
accuracy of the permit limits and to build a more robust hardness dataset.
10. Hardness and flow values used in the Reasonable Potential Analysis for this permit included:
Parameter
Value
Comments Data Source
Average Effluent Hardness (mg/L)
Total as, CaCO3 or Ca+M
140.53
Average of 6 Samples
Average Upstream Hardness (mg/L)
Total as, CaCO3 or Ca+M
25
Default value
7Q 10 summer cfs
225
Dam Release
l 10 cfs
182.62
Calculated by RPA spreadsheet
Permitted Flow (MGD)
3.5, 7.5, 10.5
Permit renewal application
Date: October 3, 2017
Permit Writer:
Page 16 of 16