NC0024911_Fact Sheet_20180906

Fact Sheet
NPDES Permit No. NC0024911
Permit Writer: Bing Bai
Division/Branch: NC Division of Water Resources/NPDES Complex Permitting
Date: September 6, 2018
Permitting Action:
❑X Renewal
❑ Renewal with Expansion
❑ New Discharge
❑ Modification
Complete applicable sections below. If not applicable, enter NA.
1. Basic Facility Information
Facility Information
Applicant/Facility Name:
Metropolitan Sewer District Buncombe County/French Broad River
Water Reclamation Facility
Applicant Address:
2028 Riverside Dr., Asheville, NC 28804
Facility Address:
2225 Riverside Dr., Woodfin, NC 28804
Permitted Flow:
40.0 MGD
Facility Type/Waste:
Major Municipal; 82 % domestic,18 % industrial
Facility Class:
Grade IV Biological WPCS
Treatment Units:
Influent screening, grit removal, primary microscreen, Rotating
Biological Contactor (RBC), intermediate clarifier, cloth media filter,
chlorine contact chamber, dechlorination, gravity thickener, belt filter
press, sludge incinerator, incinerator -ash pond.
Pretreatment Program (Y/N)
Yes. 15 CIU and 5 SIU.
County:
Buncombe
Region
Asheville
Briefly describe the proposed permitting action: MSD French Broad River Water Reclamation Facility
has applied for NPDES permit renewal, and submitted a renewal application dated May 8, 2015. This
facility serves a population of —125,000 residents and operates a pretreatment program with 15
Categorical Industrial Users and 5 Significant Industrial Users (SIUs).
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In April 2016, EPA stated that NC cannot use toxicity test results to override ammonia testing, and limits
must be included in permits. In this renewal, limits for NH3-N will be calculated based on EPA's
guidance "Aquatic Lift Ambient Water Quality Criteria For Ammonia — Freshwater 2013" and proposed
in this permit renewal. However, MSD's current treatment process (RBC) does not provide NH3-N
removal, and an Ammonia Reduction Evaluation was completed in 2016 as required by the 2011 permit
renewal. The evaluation report indicated that a compliance schedule of at least 12 years will be needed for
the facility to upgrade the plant and optimize NH3-N removal to meet proposed limits. Therefore, a
compliance schedule of 12 years for NH3-N is included in this renewal.
2. Receiving Waterbody Information:
Receiving Waterbody Information
Receiving Stream(s):
Outfall 001- French Broad River
Stream Classification:
B
Drainage Area (mi2):
966
Summer 7Q10 (cfs)
466
Winter 7Q10 (cfs):
595
Average Flow (cfs):
2140
30Q2 (cfs):
882
IWC (% effluent):
12
303(d) listed/parameter:
No
Subject to TMDL/parameter:
Statewide Mercury TMDL
Subbasin/HUC/Index No.:
04-03-02 / 06010105
USGS Topo Quad:
ERNE Weaverville
3. Effluent Data Summary
Effluent data is summarized below for the period January 2012 through September 2017.
Table 1. Effluent Data Summary
Parameter
Units
Average
Max
Min
Flow
MGD
21.14
74.60
12
CBOD
mg/1
12
47
< 2
NH3N summer
mg/1
18.2
29
3
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NH3N winter
mg/1
18.7
45
3
TSS
mg/1
14
28
< 2.5
pH
SU
7.2
7.8
6
Temperature
°C
18
25
10
DO
mg/1
7.9
14.1
5.2
Conductivity
umhos/cm
572
795
189
TN
mg/1
24.3
32.7
7.3
TP
mg/1
3.8
8.7
1.7
Fecal Coliform
#/100 ml
2.2
2420
1
Total Residual Chlorine
µg/1
< 24
40
< 24
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).
If applicable, summarize any instream data and what instream monitoring will be proposed for this
permit action:
The permittee monitors for dissolved oxygen, fecal coliform, temperature and conductivity upstream and
downstream of the discharge. Data reported in the DMRs shows similar values upstream and downstream.
No impacts are noted due to the discharge. Fecal coliform will be removed from the permit requirements
as this segment is not impaired for fecal coliform.
MSD conducted a special study to collect instream ammonia data. Data was collected at the downstream
sampling location for the period of April 2011 to December 2014. Instream ammonia averaged 0.63 mg/1,
the maximum value recorded was 2.6 mg/1.
Is this facility a member of a Monitoring Coalition with waived instream monitoring (Y/N): No
Name of Monitoring Coalition: NA
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years): The facility did not report
any limits violations for the period of October 2012 through December 2017.
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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
acute toxicity tests submitted for the permit renewal.
Summarize the results from the most recent compliance inspection: The last facility inspection conducted
in 2015 stated that the facility was well maintained and operated.
6. Water Quality -Based Effluent Limitations (WQBELs)
Dilution and Mixing Zones
In accordance with 15A NCAC 2B.0206, the following streamflows are used for dilution considerations
for development of WQBELs: 1 Q 10 streamflow (acute Aquatic Life); 7Q10 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: In lieu of BOD the
permit has secondary treatment standard limits for CBOD of 25 mg/1 as per 40 CFR 133.102.
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/1 (summer) and 1.8 mg/1 (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/1 (acute impacts). Due to analytical issues, all TRC values
reported below 50 ug/1 are considered compliant with their permit limit.
Describe any proposed changes to ammonia and/or TRC limits for this permit renewal:
Ammonia
The current permit does not have ammonia limits The permit included a special condition with
requirements to conduct a feasibility and cost analysis for two ammonia reduction scenarios; optimizing
ammonia removal under current treatment system and upgrades to the plant to meet limits. Downstream
monitoring for ammonia was required as part of the study. The target limits are 6.9 mg/1 monthly average
and 20.7 mg/1 weekly average and 17 mg/1 monthly average and 35 mg/1 weekly average for winter. The
ammonia reduction evaluation report was submitted on April 8, 2015.
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The facility uses Rotating Biological Contactors (RBC) for wastewater treatment. Performance data
obtained during the study shows that the treatment system as currently operated does not reduce ammonia
down to the target levels. During the time of the study several units were not in working order.
The facility evaluated improvements to the treatment system and is proposing upgrades to be undertaken
in the near future. Proposed upgrades include replacement of broken RBCs, improvements in the grit
removal system to improve RBC performance, wet weather flow management through flow equalization,
and primary treatment.
Biological treatment alternatives were identified and evaluated as part of the study. Cost and other factors
were considered. Activated sludge, membrane bioreactors and integrated fixed film activated sludge were
selected as the three possible technologies to be implemented. Some initial improvements have been
identified. MSD will proceed with some of the improvements and reevaluate the system performance.
The Division's ammonia policy was modified in 2016 since EPA no longer supports a toxicity test instead
of ammonia limits. Limitations for ammonia will be implemented in this permit renewal. According to
EPA's guidance "Aquatic Lift Ambient Water Quality Criteria For Ammonia — Freshwater 2013 ",
calculated limits for MSD in this permit renewal will be 14.0 mg/L for monthly average (summer) and
31.7 mg/L for monthly average (winter). Based on 40 CFR 122, weekly average limits will be capped at
35.0 mg/L for both summer and winter. No daily maximum limit will be added to the permit since
calculated daily max limits are much higher than 35 mg/L (98.5 mg/L for summer and 154.5 mg/L for
winter).
A schedule of compliance of 12 years will be included in the permit to allow the facility to implement
upgrades to be able to meet the proposed limits. The facility must comply with the proposed limits by
September 1, 2030.
Total Residual Chlorine
The permit will maintain the TRC daily maximum limit of 28 µg/1.
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/2 detection limit for "less than" values; and 4) streamflows used for dilution
consideration based on 15A NCAC 2B.0206. Effective 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.
A reasonable potential analysis was conducted on effluent toxicant data collected between January 2012
and September 2017. Pollutants of concern included toxicants with positive detections and associated
water quality standards/criteria. Based on this analysis, the following permitting actions are proposed for
this permit:
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• 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, chromium, copper, cyanide, nickel, selenium, silver and zinc.
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.
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 chronic WET limit at 12 %
effluent will continue on a quarterly frequency.
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/l) 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/l) and/or if any individual value exceeds a TBEL
value of 47 ng/1
Table 2. Mercury Effluent Data Summary
Year
2012
2013
2014
2015
2016
# of Samples
5
4
3
8
3
Annual Average, ng/L
19.1
14.6
10.9
10.9
14.2
Maximum Value, ng/L
24.70
19.00
18.70
11.60
21.70
TBEL, ng/L
47
WQBEL, ng/L
102.2
Describe proposed permit actions based on mercury evaluation: Since no annual average mercury
concentration exceeded the WQBEL, and no individual mercury sample exceeded the TBEL, no mercury
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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 the permit.
Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TMDLs/Nutrient Management Strategies and their implementation
within this permit: NA
Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: NA
If applicable, describe any special actions (HQW or ORW) this receiving stream and classification shall
comply with in order to protect the designated waterbody: NA
If applicable, describe any compliance schedules proposed for this permit renewal in accordance with
15A NCAC 2H.0107(c)(2)(B), 40CFR 122.47, and EPA May 2007Memo: A schedule of compliance for
ammonia will be included in the permit
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
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/1
BOD5/TSS for Monthly Average, and 45 mg/lfor BOD5/TSS for Weekly Average). YES
If NO, provide a justification for alternative limitations (e.g., waste stabilization pond). NA
Are 85% removal requirements for BOD5/TSS included in the permit? YES
If NO, provide a justification (e.g., waste stabilization pond). 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 2B.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
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9. Antibacksliding Review:
Sections 402(o)(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
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 3. Current Permit Conditions and Proposed Changes
Parameter
Current Permit'
Proposed Change
Basis for Condition/Change
Flow
MA 40 MGD
No change
15A NCAC 2B .0505
CBOD
MA 8 mg/1
WA 12 mg/1
No change
TBEL. Secondary treatment
standards/40 CFR 133 / 15A NCAC
2B .0406, Secondary treatment
standards equivalent for CBOD
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NH3-N
Monitor only
Maintain daily monitoring.
Limits will become effective on
October 1, 2030. A 12-year
compliance schedule is added to
permit.
Summer:
MA 14 mg/L
WA 35 mg/L
Winter:
MA 31.7 mg/L
WA 35 mg/L
WQBEL. Based on protection of
State WQ criteria. 15A NCAC
2B.0200.
EPA's guidance "Aquatic Life
Ambient Water Quality Criteria For
Ammonia — Freshwater 2013"
Limits will be effective 12 years
from effective date of this permit
TSS
MA 30 mg/1
WA 45 mg/1
No change
TBEL. Secondary treatment
standards/40 CFR 133 / 15A NCAC
2B .0406
Fecal coliform —
Effluent
MA 200 /100m1
WA 400 /100m1
No change
WQBEL. State WQ standard, 15A
NCAC 2B .0200
Fecal coliform —
Instream
Weekly
Removed from permit
Receiving stream is not impaired
with fecal coliform
DO
> 5 mg/1
No change
WQBEL. State WQ standard, 15A
NCAC 2B .0200
pH
6 — 9 SU
No change
WQBEL. State WQ standard, 15A
NCAC 2B .0200
Total Nitrogen
Monitor Only
No change
15A NCAC 2B.0200
Total
Phosphorus
Monitor Only
No change
15A NCAC 2B.0200
Hardness
No requirement
Quarterly monitor, effluent and
upstream
Data required to calculate standards
for hardness dependent metals.
Conductivity
Monitor 3/week
No change
15A NCAC 2B.0200.
Total Copper
Monitor quarterly
Removed from permit
No RP from RPA
Total Zinc
Monitor quarterly
Removed from permit
No RP from RPA
Total Silver
Monitor quarterly
Removed from permit
No RP from RPA
Toxicity Test
Chronic limit, 12
% effluent
No change
WQBEL. No toxics in toxic
amounts. 15A NCAC 2B.0200
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Effluent
Pollutant Scan
Annual
Reduce to three times per permit
cycle
40 CFR 122
Mercury
Minimization
Plan (MMP)
No requirement
Add MMP Special Condition
WQBEL. Consistent with 2012
Statewide Mercury TMDL
Implementation.
Electronic
Reporting
No requirement
Add Electronic Reporting
Special Condition
In accordance with EPA Electronic
Reporting Rule 2015.
1. MGD — Million gallons per day, MA - Monthly Average, WA — Weekly Average, DM — Daily Max
Special Condition A. (6) Groundwater Requirements has been revised. Detailed groundwater monitoring
requirements and sampling plan have been included in the attachment to the permit (See Attachment 1).
The Permittee shall work directly with DWR Ashville Regional Office on the sampling plan. If any
change is made to the sampling plan, the Permittee shall submit the approved plan to the Division's
NPDES Complex Permitting Section.
13. Public Notice Schedule:
Permit to Public Notice: 05/29/2018
Per 15A NCAC 2H .0109 & .0111, The Division will receive comments for a period of 30 days following
the publication date of the public notice. Any request for a public hearing shall be submitted to the
Director within the 30 days comment period indicating the interest of the party filing such request and the
reasons why a hearing is warranted.
14. 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
15. Fact Sheet Attachments (if applicable):
• RPA Spreadsheet Summary
• Dissolved Metals Implementation/Freshwater or Saltwater
• NH3-N and TRC WLA
• Mercury TMDL Evaluation
• NH3-N limits development
• Monitoring Violation Reports
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