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HomeMy WebLinkAboutNC0045993_Fact Sheet_20240423 Fact Sheet NPDES Permit No. NC0045993 Permit Writer/Email Contact: Sergei Chernikov, Ph.D. / sergei.chernikov@deq.nc.gov Date: February 7, 2024 Division/Branch: NC Division of Water Resources/NPDES Industrial Permitting Fact Sheet Template: Version 09Jan2017 Permitting Action: ☒ 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 (POTW), EPA Form 2A, 3 effluent pollutant scans, 4 2nd 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: ATI Specialty Materials, LLC/Monroe Facility  Applicant Address: P.O. Box 5030  Facility Address: 2020 Ashcraft Avenue, Monroe, NC 28110  Permitted Flow: No flow limit  Facility Type/Waste: Major Industrial  Facility Class: Class I  Treatment Units: two holding ponds and an oil/water skimmer  Pretreatment Program (Y/N) N  County: Union  Region Mooresville   Briefly describe the proposed permitting action and facility background: ATI Specialty Materials – Monroe Facility (ATI) applied for an NPDES permit renewal on July 31, 2018. ATI produces nickel and titanium alloys in billet, bar, and rod form. Such processes are regulated under 40 CFR 471.32 and 471.62, Nonferrous Metals Forming and Metal Powders. Treatment consists of two holding ponds and an oil/water skimmer used as needed. The discharge from the pond, on which there is no flow limit, consists of stormwater, process flow (from the rolling mill and forging), blowdown from the cooling towers, and noncontact cooling water. The majority of the cooling water used at the plant is recycled several times a day being filtered through sand filters and redistributed throughout the plant for various cooling loads. The facility has an Outfall 001 that discharges to Richardson Creek, class C waters in the Yadkin-Pee Dee River Basin. Richardson Creek is listed in the 2022 North Carolina 303(d) list as impaired for Benthos due to fair, poor, or severe bioclassification. The previous permit was issued on May 2, 2014 and expired on January 31, 2019. The 2014 permit was contested by ATI later primarily due to the percent concentration of the whole effluent toxicity test (WET). A settlement was negotiated that a permit modification would be made to re-evaluate and revise the limits for the chronic toxicity test, whereupon ATI filed a Notice of Withdrawal of the contested case. As a result, the chronic toxicity test permit limit was modified from an effluent concentration of 58% for all the quarterly tests to an effluent concentration of 52% for the May and August tests and 40% for the February and November tests. ATI requested an Owner & Facility name change in December 2022. TDY Industries, LLC (the "Company") will be undergoing an internal restructuring transaction pursuant to which there will be transfer of assets and obligations from the Company to ATI Specialty Materials, LLC, an affiliate of the Company. This restructuring will change the legal entity structure for the business but will not otherwise impact the business operations or permits. After the name change, the owner’s name is ATI Specialty Materials, LLC and the facility name is ATI Specialty Materials – Monroe Facility. 2. Receiving Waterbody Information: Receiving Waterbody Information  Outfalls/Receiving Stream(s): Outfall 001 – Richardson Creek   Stream Segment: 13-17-36-(5)   Stream Classification: C   Drainage Area (mi2): 54.6   Summer 7Q10 (cfs) 0.27   Winter 7Q10 (cfs): 0.46   30Q2 (cfs): 0.65   Average Flow (cfs): 49   IWC (% effluent): 51   303(d) listed/parameter: Yes – Benthos (2022)   Subject to TMDL/parameter: Yes/State-wide Mercury TMDL implementation.  Basin/Sub-basin/HUC: 03-07-14/030401050504  USGS Topo Quad: H16NE  The IWC for this facility may vary for each renewal. During this renewal, the facility provided average flow of 0.183 MGD for the last three years. This number was used for the permit development. 3. Effluent Data Summary Effluent data for Outfall 001 is summarized below for the period of April 2019 through March 2022. Table 3. Effluent Data Summary Outfall 001 Parameter Units Average Max Min Permit Limit  Flow MGD 0.178 2.3 0.013 NA  NH3N summer mg/L < 0.12 0.71 < 0.1 DM 10 MA 2.0  NH3N winter mg/L < 0.105 0.17 < 0.1 DM 20 MA 4.0  TSS mg/L < 6.89 21.4 2.7 DM 45.0 MA 30.0  Oil & Grease mg/L < 4.9 5 1.4 DM 15 MA 10  Temperature ° C 20.7 30.1 9.4   Conductivity umhos/cm 211.26 432 91   pH SU 7.3 8.3 6.9 6.0 ≤ pH ≤ 9.0  Total Chromium lb/day 0.004 0.022 0 DM 0.15 MA 0.06  Fluoride mg/L 0.43 1.2 0.044 DM 38.9 MA 3.5  Total Cyanide µg/L < 7.5 8 < 0.5 DM 31.8 MA 7.3  Total Nickel lb/day 0.017 0.084 0.004 DM 0.22 MA 0.15  Total Lead µg/L < 5 < 5 < 5 DM 55 MA 43  Total Zinc lb/day 0.021 0.083 0 DM 1.8 MA 0.75  Total Copper µg/L 2.8 19.8 0.01    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/l 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: This facility is not a coalition member of the Yadkin/Pee Dee River Basin Association. The current permit requires instream monitoring for conductivity only. Upstream and downstream data ranging from April 2019 through March 2022 are summarized in table 4 for instream data analysis. Table 4. Instream Data Summary Parameter Units Minimum Maximum Average Location  Conductivity umhos/cm 91 371 162.56 U    98.2 393 176.26 D  Note: Instream data are summarized for the period of April 2019 through March 2022.   Conductivity: there is no water quality standard for conductivity. Based on the t-Test, it was concluded with 95% confidence that statistically significant difference did not exist (p-value > 0.05) between upstream and downstream conductivity. The effluent did not appear to impact the stream conductivity. Temperature: Instream temperature requirements were specified in footnote #4 in Section A. (1) of the existing permit. Based on internal discussions within the NPDES Permitting Branch, if a facility includes noncontact cooling water, instream temperature limits shall be included. Per 15A NCAC 02B .0211, for Class C freshwaters in lower piedmont area, the downstream water shall not exceed 2.8 degrees C (5.04 degrees F) above the natural water temperature (upstream water temperature), and in no case to exceed 32 degrees C (89.6 degrees F). In this renewed permit, upstream and downstream sample locations and associated limits/monitoring requirements are added to the table of Section A. (1). Upstream and downstream temperatures shall be measured during the discharge event, together with the effluent temperature measurement. This draft permit maintains the instream conductivity sampling requirements for monitoring purposes, and clearly identified instream temperature limits and monitoring frequency in the table of Section A. (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): From April 2017 through March 2022, the facility reported one violation for aquatic toxicity permit limit in May 2021, which was processed to NOD. It was indicated the violation was due to a lab error. Summarize the compliance record with aquatic toxicity test limits and any second species test results (past 5 years): From April 2017 through March 2022, the facility passed 19 quarterly chronic toxicity tests. The toxicity test in May 2021 was shown as invalid. Another test was performed in July 2021 and the result was “Pass”. Summarize the results from the most recent compliance inspection: The last facility inspection conducted on October 20, 2021, reported that the records were kept and maintained as required by the permit, and effluent was clear with no visible suspended solids at time of inspection. 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: 1Q10 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/l 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: There are no BOD limits for this facility because the onsite sanitary sewer discharges to City of Monroe’s WWTP. 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/l) 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: There are no proposed changes. The existing limitations are based on the Division’s Policy(Refer to Policy update of March 11, 2015, for details). 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 ½ 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 2018 and 2022.  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: 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:  Total Copper and Total Nickel. 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: Total Cyanide and Total Cadmium. 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: Total Arsenic, Total Beryllium, Chromium III, Chromium VI, Total Fluoride, Total Lead, Total Molybdenum, Total Selenium, Total Silver, and Total Zinc. Attached are the RPA results, as well as a copy of the guidance entitled “NPDES Implementation of Instream Dissolved Metals Standards – Freshwater Standards”. 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: The last permit specified that the effluent discharge shall at no time exhibit observable inhibition of reproduction or significant mortality to Ceriodaphnia dubia at an effluent concentration of 52% for the May and August tests and 40% for the February and November tests. This permit will have Ceriodaphnia test at an effluent concentration of 51% based on the latest flow data. 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/l Describe proposed permit actions based on mercury evaluation: The facility reported only one mercury data point of <200.0 ng/L. The facility will be required to use more sensitive method (EPA 1631E). 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 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 7. Technology-Based Effluent Limitations (TBELs) Industrials (if not applicable, delete and skip to next Section) Describe what this facility produces: ATI produces nickel and titanium alloys in billet, bar, and rod form. List the federal effluent limitations guideline (ELG) for this facility: 40 CFR 471.32 and 471.62 If the ELG is based on production or flow, document how the average production/flow value was calculated: This ELG is based on production. The daily average production in Million pounds per day can be found in two tables below. C - Nickel-Cobalt Forming Average daily prod.  471.32 (Million lb.)       Rolling contact cooling water 0.125  Forging equipment cleaning water 0.4  Forging contact cooling water 0.4  Forging press hyd. leakage 0.4  Misc. wastewater sources 0.53   F - Titanium Forming Average daily prod.  471.62 (Million lb.)       Rolling contact cooling water 0.054  Forging contact cooling water 1.18  Forging equipment cleaning water 1.18  Forging press hyd. leakage 1.18  Misc. wastewater sources 1.24   For ELG limits, document the calculations used to develop TBEL limits: Attached please find spreadsheet that calculates ELG limits and compares them Water Quality Based Limits. If any limits are based on best professional judgement (BPJ), describe development: NA Document any TBELs that are less stringent than previous permit: TBEL limits for Total Zinc are less stringent than previous limits. These limits are based on the most current production level. Such changes occur periodically during permit renewal and do not violate antibacksliding provisions of the Clean Water Act. 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 9. Antibacksliding Review: Sections 402(o)(2) and 303(d)(4) of the CWA and federal regulations at 40 CFR 122.44(l) 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): : TBEL limits for Total Zinc are less stringent than the previous limits. The limits for Total Cyanide, Total Fluoride, and Total Lead in previous permit were based in the RPA results. During this permitting cycle, the RPA did not indicate a need for limits for these parameters. Therefore, TBELs have been implemented in the permit for Total Cyanide, Total Fluoride, and Total Lead. If YES, confirm that antibacksliding provisions are not violated: These limits are based on the most current production level. Such changes occur periodically during permit renewal and do not violate antibacksliding provisions of the Clean Water Act. 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(o) 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. While NPDES regulated facilities would initially be required to submit additional NPDES reports electronically effective December 21, 2020, EPA extended this deadline from December 21, 2020, to December 21, 2025. The current compliance date, effective January 4, 2021, was extended as a final regulation change published in the November 2, 2020 Federal Register. This permit contains the requirements for electronic reporting, consistent with Federal requirements. 12.Summary of Proposed Permitting Actions: A. Table. Current Permit Conditions and Proposed Changes. Parameter Current Permit Proposed Change Basis for Condition/Change  Flow No limit No change Wastewater is combined with stormwater.  Total Chromium  MA 0.06 lb/day DM 0.15 lb/day 2/Month Monitoring MA 0.04 lb/day DM 0.09 lb/day No change in monitoring TBEL. Based on the current production level. 40 CFR 471.32 and 471.62   Total Chromium  MA 0.06 lb/day DM 0.15 lb/day 2/Month Monitoring MA 0.04 lb/day DM 0.09 lb/day No change in monitoring TBEL. Based on the current production level. 40 CFR 471.32 and 471.62  Total Fluoride  MA 3.5 mg/L DM 38.9 mg/L 2/Month Monitoring MA 43.34 lb/day DM 98.77 lb/day No change in monitoring TBEL. Based on the current production level. 40 CFR 471.32 and 471.62 (for pound-based limit)  Total Cyanide  MA 7.3 (g/L DM 31.8 (g/L 2/Month Monitoring MA 0.171 lb/day DM 0.414 lb/day No change in monitoring TBEL. Based on the current production level. 40 CFR 471.32 and 471.62 (for pound-based limit)  Total Nickel  MA 0.15 lb/day DM 0.22 lb/day 2/Month Monitoring MA 0.09 lb/day DM 0.13 lb/day No change in monitoring TBEL. Based on the current production level. 40 CFR 471.32 and 471.62  Total Lead  MA 43.0 (g/L DM 55.0 (g/L Monthly monitoring MA 0.29 lb/day DM 0.6 lb/day 2/Month Monitoring TBEL. Based on the current production level. 40 CFR 471.32 and 471.62 Monitoring was increased to be consistent with other TBEL parameters  Total Zinc  MA 0.75 lb/day DM 1.8 lb/day 2/Month Monitoring MA 0.87 lb/day DM 2.09 lb/day No change in monitoring TBEL. Based on the slight increase in the current production level. 40 CFR 471.32 and 471.62  Total Copper Quarterly effluent monitoring only MA 15.38 (g/L DM 18.96 (g/L 2/Month monitoring WQBEL. Based on protection of State WQ standard (15A NCAC 2B.0200) and RPA results Monitoring was increased due to the addition of the limit  Total Cadmium  No monitoring Addition of quarterly effluent monitoring WQBEL. Based on protection of State WQ standard (15A NCAC 2B.0200) and RPA results  NH3-N Summer: MA 2.0 mg/L DM 10.0 mg/L Winter: MA 4.0 mg/L DM 20.0 mg/L 2/Month monitoring No change WQBEL. Based on protection of State WQ standard. 15A NCAC 2B.0200 and Division’s policy on Ammonia  TSS MA 30.0 mg/L DM 45.0 mg/L 2/Month monitoring No change TBEL. Secondary treatment standards/40 CFR 133 / 15A NCAC 2B .0406  pH 6.0 – 9.0 SU Monthly monitoring No change WQBEL. State WQ standard, 15A NCAC 2B .0200   pH 6.0 – 9.0 SU Monthly monitoring No change WQBEL. State WQ standard, 15A NCAC 2B .0200  Oil and Grease MA 10.0 mg/L DM 15.0 mg/L 2/Month monitoring No change WQBEL. Based on state WQ standard, 15A NCAC 2B .0200.  Temperature Effluent monitoring and limit Weekly monitoring Addition of instream monitoring State WQ standard, 15A NCAC 2B .0200  Conductivity Monitor only - effluent and instream 2/Month monitoring No change State monitoring requirements 15A NCAC 2B .0500  Toxicity Test Chronic limit, 58% effluent Quarterly monitoring Chronic limit, 51% effluent No change in monitoring WQBEL. No toxics in toxic amounts. 15A NCAC 2B.0200 and 15A NCAC 2B.0500. IWC is based on the latest flow numbers.  Electronic Reporting Electronic Reporting Special Condition No change In accordance with EPA Electronic Reporting Rule 2015.  MGD – Million gallons per day, MA - Monthly Average, WA – Weekly Average, DM – Daily Max 13. Public Notice Schedule: Permit to Public Notice: xx/xx/2024 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. NPDES Division Contact: If you have questions regarding any of the above information or on the attached permit, please contact Sergei Chernikov at (919) 707-3606 or via email at sergei.chernikov@deq.nc.gov 15. 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 16. Proposed Changes in the Draft Permit The limits for Total Copper were added to the permit based on the results of the Reasonable Potential Analysis. The quarterly monitoring for Total Cadmium was added to the permit based on the results of the Reasonable Potential Analysis. The monitoring for Total Lead was increased from Monthly to 2/Month to be consistent with monitoring for other TBEL parameters. The monitoring for Total Copper was increased from Quarterly to 2/Month due to be implementation of the water quality based Total Copper limit. The temperature monitoring was added to the permit to determine compliance with 15A NCAC 2B .0200. The Technology Based Effluent Limits for Total Chromium, Total Fluoride, Total Cyanide, Total Nickel, Total Lead, and Total Zinc have been recalculated based on the latest production data. The instream waste concentration was changed from 58% to 51% based on the current flow rate. 17. Fact Sheet Attachments (if applicable): RPA Spreadsheet Summary ELG Spreadsheet Dissolved Metals Implementation/Freshwater or Saltwater 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 Quality Standards/Aquatic Life Protection Parameter Acute FW, µg/l (Dissolved) Chronic FW, µg/l (Dissolved) Acute SW, µg/l (Dissolved) Chronic SW, µg/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: FW= Freshwater, SW= Saltwater Calculation = Hardness dependent standard 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 2B.0200 (e.g., arsenic at 10 µg/l for human health protection; cyanide at 5 µg/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, µg/l  Cadmium, Acute WER*{1.136672-[ln hardness](0.041838)} ∙ e^{0.9789 [ln hardness]-3.443}   Cadmium, Acute Trout waters WER*{1.136672-[ln hardness](0.041838)} ∙ e^{0.9789[ln hardness]-3.866}  Cadmium, Chronic WER*{1.101672-[ln hardness](0.041838)} ∙ e^{0.7977[ln hardness]-3.909}  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-[ln hardness](0.145712)} ∙ e^{1.273[ln hardness]-1.460}  Lead, Chronic WER*{1.46203-[ln hardness](0.145712)} ∙ e^{1.273[ln hardness]-4.705}  Nickel, Acute WER*0.998 ∙ e^{0.8460[ln hardness]+2.255}  Nickel, Chronic WER*0.997 ∙ e^{0.8460[ln hardness]+0.0584}  Silver, Acute WER*0.85 ∙ e^{1.72[ln 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 Permitting Guidance/WQBELs 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. 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 1Q10 using the formula 1Q10 = 0.843 (s7Q10, cfs) 0.993 Effluent hardness and upstream hardness, site-specific data is preferred Permitted flow Receiving stream classification 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. 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) + (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 1Q10 flow. 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. 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. The RPA spreadsheet uses a mass balance equation to determine the total allowable concentration (permit limits) for each pollutant using the following equation: Ca = (s7Q10 + Qw) (Cwqs) – (s7Q10) (Cb) Qw Where: Ca = allowable effluent concentration (µg/L or mg/L) Cwqs = NC Water Quality Standard or federal criteria (µg/L or mg/L) Cb = background concentration: assume zero for all toxicants except NH3* (µg/L or mg/L) Qw = permitted effluent flow (cfs, match s7Q10) s7Q10 = 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: 1Q10 = 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 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. 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. 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.