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HomeMy WebLinkAboutNC0004979_Draft WW Permit Fact Sheet_20150505NCDENR/DWR FACT SHEET FOR NPDES PERMIT DEVELOPMENT Duke Energy Carolinas, LLC – Allen Steam Station NC0004979 Facility Information Applicant/Facility Name: Duke Energy Carolinas, LLC – Allen Steam Station Applicant Address: P.O. Box 1006, Charlotte, North Carolina 28201 Facility Address: 253 Plant Allen Road, Belmont, North Carolina 28012 Permitted Flow No limit Type of Waste: 100% industrial Primary SIC Code: 4911 – Electric Services Facility/Permit Status: Class I/Active; Renewal County: Gaston County Miscellaneous Receiving Stream: Catawba River (11- 123.5), South Fork Catawba River (Lake Wylie) Regional Office: Mooresville Stream Classification: WS-IV B (Catawba River) and WS-V B (South Fork Catawba River) State Grid / USGS Quad: G14 NE 303(d) Listed? Yes (Catawba River Only) Permit Writer: Sergei Chernikov, Ph.D. Subbasin: 03-08-34 Date: January 9, 2015 Drainage Area (mi2): 635 (Catawba River) 001: Lat. 35 11’ 23” N Long. 81 00’ 45” W 002: Lat. 35 10’ 30” N Long. 81 00’ 23” W 002A: Lat. 35 11’ 34” N Long. 81 00’ 22” W 002B: Lat. 35 11’ 36” N Long. 81 00’ 30” W 004: Lat. 35 11’ 35” N Long. 81 00’ 22” W Summer 7Q10 (cfs) 95 Winter 7Q10 (cfs): 95 30Q2 (cfs) 314 Average Flow (cfs): 24700 IWC (%): 20 (Outfall 002) Summary: Duke Energy’s Allen Steam Station is a coal fired steam electric plant in Gaston County. Applicable effluent guidelines are in 40 CFR 423.12. The facility is also subject to the Cooling Water Intake Structure Rule (316(b) Rule) per 40 CFR 125.95.  Outfall 001 is comprised of once through, non-contact condenser cooling water. The average flow through this outfall is currently 649.4 MGD, according to the permit application. This outfall discharges to the South Fork Catawba River.  Outfall 002 is the ash basin discharge. This outfall includes domestic wastewater, stormwater from the coal pile area, ash sluice, wastewater from turbine non-destructive testing, a yard drain sump, water treatment filter backwash, laboratory wastes, and the power house sump at Unit 5. The domestic waste is pre-treated by a septic tank. Outfall 002 NPDES Permit Fact Sheet NC0004979 Page 2 of 7 wastewater is treated using chemical coagulation, settling, pH neutralization, and ion exchange. This outfall discharges to the Catawba River.  Outfalls 002A and 002B are intermittent discharges of emergency overflows (coal yard sump overflow and power house sump overflow, respectively). Both outfalls discharge to the Catawba River. Federal regulations (effluent guidelines) require a daily max TSS limit for coal pile runoff (from a rain event) of 50 mg/L. The layout for this coal yard sump is such that an overflow would be low volume wastewater instead of coal pile runoff. Chemical metal cleanings do not go to this sump.  Outfall 003 is miscellaneous once through non-contact cooling water and seal water. This outfall discharges to the South Fork Catawba River.  Outfall 004 is also miscellaneous once through non-contact cooling water. This includes a small amount of intake screen backwash and car wash rinse water. This outfall discharges to the Catawba River.  Outfall 005 is internal, discharging to the ash pond. It is comprised of flue gas desulfurization wastewater. The treatment facilities at this outfall consist of flow equalization, pH stabilization using lime addition, chemical precipitation, clarification, gravity filtration, biological selenium removal, aerated sludge holding, and a sludge filter press.  Outfall 010 is combined flow from all seeps. This outfall discharges to the Catawba River.  Outfall 011 is combined flow from all toe drains. This outfall discharges to the Catawba River SEEPS – OUTFALL 010 The facility identified 9 unpermitted seeps from the ash settling basin. Seeps can be classified as either engineered seeps (toe drains) from the earthen dam or non-engineered seeps that occur as wastewater moves from the ash settling basin into groundwater and then into surface water, either directly or after emerging on land. Engineered seeps can be captured and routed through a permitted outfall. The non-engineered seeps represent a treatment system that has the potential to contaminate groundwater and surface water. The original design and location of the impoundment are such that wastewaster is not contained and directed to only engineered outfalls as the NPDES program generally contemplates, but wastes are also being released to groundwater and emerging in the form of seeps at the surface at diffuse and remote locations, with wastewater then flowing into surface waters depending on site specific factors. Potential groundwater contamination is regulated through North Carolina's 2L program. The CWA NPDES permitting program does not normally envision permitting of uncontrolled releases from treatment systems; such releases are difficult to monitor and control, and it is difficult to accurately predict their impact on water quality. Releases of this nature would typically be addressed through an enforcement action requiring their elimination rather than permitting. The non-engineered seeps at this facility represent a unique circumstance, where the occurrence of the seeps is attributable to an original pond design that will require long-term action to fully address. Recent North Carolina legislation (Coal Ash Management Act of 2014) establishes a framework for addressing all coal ash impoundments in the state to ensure that groundwater and surface water are adequately protected through closure or other measures. However, action to close NPDES Permit Fact Sheet NC0004979 Page 3 of 7 or otherwise address coal ash impoundments and their threats to surface waters and groundwater will occur over a long term of those actions. In light of the long-term nature of action to fully address these impoundments, the Division is proposing, as an interim measure, to ensure that all non- engineered seeps are appropriately identified, monitored, and subject to protective effluent limits by including the seep discharges as authorized discharges in the facility's NPDES permit. The permit includes requirements to regularly inspect for new seeps, monitoring requirements for all identified seeps, and applicable effluent limits which ensure that the seeps will not result in unacceptable impacts to the receiving stream. The facility identified 9 unpermitted seeps and conducted chemical analysis of the discharges. The flow volume for 7 seeps was determined to be 0.006 MGD. The flow volume for 2 seeps that account for the flow from Toe Drains was determined to be 0.0091 MGD. For the purposes of permitting it was assumed that all seeps and Toe Drains reach the surface water. The water in the seeps has percolated through the walls of the dike or through the bottom of the ash pond. The soil in the dike or the bottom of the ash pond served as a filter, which removed some of the pollutants from the wastewater. Consequently, most of the pollutants in the seep discharge have a lower concentration of the constituents compared to the ash pond discharge. Therefore, pumping the water from the seeps back to the ash pond is not likely to result in any additional pollutant removal. Such pumping would also require construction activities that would disturb and damage sensitive buffer areas. The construction activities would require 401 permits, which will create a substantial delay with ash pond decommissioning and potentially jeopardize the deadlines for coal ash removal established in the North Carolina Coal Ash Management Act of 2014. In addition, the combined seep flow (including Toe Drains) represents only 0.08 % of the ash pond discharge. Considering lower pollutant concentration for most of the chemical compounds in the seep discharge, this discharge has an extremely low impact on the receiving stream. The maximum allowable parameter concentration for seeps was determined by multiplying the highest concentration for a baseline seep data by 10. These values are substantially lower than the allowable concentration determined by the Reasonable Potential Analysis for the combined seep flow. The maximum allowable concentrations for Pb and TDS were established at the level of the water quality standards. ASH POND DAMS Seepage through earthen dams is common and is an expected consequence of impounding water with an earthen embankment. Even the tightest, best-compacted clays cannot prevent some water from seeping through them. Seepage is not necessarily an indication that a dam has structural problems, but should be kept in check through various engineering controls and regularly monitored for changes in quantity or quality which, over time, may result in dam failure. TOE DRAINS – OUTFALL 011 The Allen Active Ash Basin dam consists of the north dike and the east dike. Both dikes have internal drainage systems. Any surface water flow from these drainage systems will pass through seep locations S-3 or S-4. Toe drains have been incorporated into the permit under the Outfall 011. REASONABLE POTENTIAL ANALYSIS(RPA)-OUTFALL 002, OUTFALL 010, OUTFALL 011 The Division conducted EPA-recommended analyses to determine the reasonable potential for toxicants to be discharged at levels exceeding water quality standards/EPA criteria by this facility from outfall 002 (Ash Pond). Calculations included: As, Be, Cd, Chlorides, F, Total Phenolic Compounds, Cr, Cu, CN, Pb, Hg, Mo, Ni, Se, Ag, Zn, Co, Sulfate, Al, Ba, B, Fe, Mn, Sb, and Tl (please see attached). The analysis indicates no reasonable potential to violate the surface water quality standards or EPA criteria. NPDES Permit Fact Sheet NC0004979 Page 4 of 7 An RPA was also conducted for the combined flow from the seeps. Calculations included: As, Cd, Chlorides, Cr, Cu, F, Pb, Hg, Mo, Ni, Se Zn, Sulfate, Al, Ba, B, Fe, Mn, Sb, and Tl (please see attached). The analysis indicates no reasonable potential to violate the water quality standards or EPA criteria. The flow volume for the combined seep flow was measured at 0.006 MGD. However, the flow of 0.5 MGD was used for the RPA to incorporate a safety factor, account for potential new seeps that might emerge in the future or increase in flow volume at the existing seeps. An RPA was also conducted for the combined Toe Drains flow. Calculations included: As, Cd, Chlorides, Cr, Cu, F, Pb, Hg, Mo, Ni, Se Zn, Sulfate, Al, Ba, B, Fe, Mn, Sb, and Tl (please see attached). The analysis indicates no reasonable potential to violate the water quality standards or EPA criteria. The flow volume for the combined Toe Drains flow was measured at 0.0091 MGD. However, the flow of 0.01 MGD was used for the RPA to incorporate a safety factor and account for potential increase in flow volume. The RPA analysis indicates that existing discharges from the facility outfalls will not cause contravention of the state water quality standards/ EPA criteria. TECHNOLOGY BASED EFFLUENT LIMITS-OUTFALL 002, OUTFALL 005, OUTFALL 010, OUTFALL 011 The existing federal regulations require development of Technology Based Effluent Limits (TBELs) for the parameters of concern. Since the EPA has not promulgated any new Effluent Guidelines for Power Plants since 1982, the Division has reviewed the performance of the existing coal-fired power plants to establish TBELs: Marshall Steam Station, Belews Steam Station, and Allen Steam Station. Two of these facilities (Belews and Allen) were used by EPA to establish the proposed Effluent Guidelines for Power Plants. The Division focused on the following parameters: Total Arsenic, Total Mercury, Total Selenium, and Nitrate/nitrite as N. These parameters are consistent with the parameters selected by EPA in the proposed Effluent Guidelines. The Division agrees with the EPA statement from the proposed Effluent Guidelines that justifies TBEL limitations for only four pollutants of concern: “Effluent limits and monitoring for all pollutants of concern is not necessary to ensure that the pollutants are adequately controlled because many of the pollutants originate from similar sources, have similar treatabilities, and are removed by similar mechanisms. Because of this, it may be sufficient to establish effluent limits for one pollutant as a surrogate or indicator pollutant that ensures the removal of other pollutants of concern.” Based on the review of the effluent data for the past 5 years the Division established the following TBELs for the coal-fired power plants in North Carolina. The monthly average limits for Total Arsenic and Total Selenium are based on 95th percentile of the effluent data, which is consistent with the EPA methodology, and daily maximum limits for these constituents are based on the 99.9th percentile of the effluent data. The Total Mercury limit is based on the Statewide Mercury TMDL implementation strategy and was established by the Division previously. A statewide mercury TMDL was developed to estimate the proportions of mercury contributions to water and fish from wastewater discharges, in-state air sources, and out-of-state air sources, and to calculate appropriate reductions needed. The TMDL was approved by EPA on 10/12/2012. Total Arsenic – 10.5 µg/L (Monthly Average); 14.5 µg/L (Daily Maximum) Total Selenium – 13.6 µg/L (Monthly Average); 25.5 µg/L (Daily Maximum) Total Mercury – 47.0 ng/L (Monthly Average); 47.0 ng/L (Daily Maximum) The Division does not have any long-term data for Nitrate/nitrite as N. Therefore, the limits for this parameter are based on the proposed EPA Effluent Guidelines. NPDES Permit Fact Sheet NC0004979 Page 5 of 7 Nitrate/nitrite as N – 0.13 mg/L (Monthly Average); 0.17 mg/L (Daily Maximum) Facility is allowed 4.5 years from the effective date of the permit to comply with the TBELs (Outfall 005 only). This time period is provided in order for the facility to budget, design, and construct the treatment system. The compliance schedule is consistent with the proposed EPA Effluent Guidelines that require compliance with the TBELs “as soon as possible within the next permit cycle beginning July 1, 2012”. Since the permit cycle is 5 years, the Effluent Guidelines will allow the facility to comply with the TBELs by June 30, 2022. This permit has a more stringent requirements, the facility shall comply with the TBELs by the end of 2019. CWA SECTION 316(a) TEMPERATURE VARIANCE – OUTFALL 001 The facility has a temperature variance. In order to maintain the variance the facility has to conduct annual biological and chemical monitoring of the receiving stream to demonstrate that it has a balanced and indigenous macroinvertebrate and fish community. The latest BIP (balanced and indigenous population) report was submitted to DWR in November of 2014. The DWR has reviewed the report and concluded that the receiving stream near Allen Steam Station has a balanced and indigenous macroinvertebrate and fish community. CWA SECTION 316(b) The permittee shall comply with the Cooling Water Intake Structure Rule per 40 CFR 125.95. The Division approved the facility request for an alternative schedule in accordance with 40 CFR 125.95(a)(2). The permittee shall submit all the materials required by the Rule with the next renewal application. INSTREAM MONITORING-OUTFALL 002 The permit required semi-annual upstream and downstream monitoring near the ash pond discharge. The upstream site (Station 250) is approximately 1.1 miles upstream of the discharge and downstream location (Station 235) is approximately 3 miles downstream of the discharge. These monitoring stations have been established through the BIP monitoring program, which was required to maintain the 316(a) temperature variance. The monitored parameters are: As, Cd, Cr, Cu, Hg, Pb, Se, Zn, and Total Dissolved Solids (TDS). The majority of the results are below detection level (Hg, As, Cd, Cr, Pb, Se), the rest of the results are below water quality standards (Cu, Zn, TDS). No parameter demonstrate increase in the concentration at the monitoring stations below the discharge. It is required that the monitoring of the instream stations will continue during the next permit cycle. It is also required that the facility uses low level method 1631E for all Hg analysis. FISH TISSUE MONITORING-NEAR OUTFALL 002 The permit required fish tissue monitoring for As, Se, and Hg near the ash pond discharge once every 5 years. This frequency is consistent with EPA guidance. Redear sunfish and largemouth bass tissues were analyzed for these trace elements. The results were below action levels for Se and Hg (10.0 µg/g – Se, 0.4 µg/g – Hg, NC) and screening value for As (1.2 – µg/g, EPA). These results are consistent with the previous monitoring results. TOXICITY TESTING-OUTFALL 002 Current Requirement: Outfall 002 – Chronic P/F @ 20% using Ceriodaphnia Recommended Requirement: Outfall 002 – Chronic P/F @ 20% using Ceriodaphnia This facility has passed all toxicity tests during the previous permit cycle, please see attached. NPDES Permit Fact Sheet NC0004979 Page 6 of 7 COMPLIANCE SUMMARY During the last 5 years, the facility has exceeded limits 4 times, please see attached. Three limit violations were for temperature (Outfall 001) and one limit violation was for Fe (Outfall 002). PERMIT LIMITS DEVELOPMENT  Outfall 001 – Condenser Cooling Water (CCW): Currently, only temperature is limited in this outfall. Summer and winter thermal limits have been established in support of the 316(a) temperature variance.  The temperature limits (Outfall 001) are based on the North Carolina water quality standards (15A NCAC 2B .0200) and 316(a) Thermal Variance.  The limits for Oil and Grease and Total Suspended Solids (Outfalls 002, 002A, 002B, 004, and 011) were established in accordance with 40 CFR 423.  The pH limits (Outfalls 002, 002A, 002B, 010, and 011) in the permit are based on the North Carolina water quality standards (15A NCAC 2B .0200).  The limits for Total Copper and Total Iron (Outfalls 002, 002A, 002B, and 011) were established in accordance with 40 CFR 423.  The turbidity limit in the permit (Outfalls 002 and 011) is based on the North Carolina water quality standards (15A NCAC 2B .0200).  The Technology Based Effluent Limits for Total Arsenic, Total Mercury, Total Selenium, and Nitrate/nitrite as N (Outfalls 010 and 011) are based on the requirements of 40 CFR 125.3(a) , 40 CFR 122.44(a)(1); 40 CFR 125.3(c) and (d).  The Technology Based Effluent Limits for Total Arsenic, Total Selenium, and Nitrate/nitrite as N (Outfall 005) are based on the requirements of 40 CFR 125.3(a) , 40 CFR 122.44(a)(1); 40 CFR 125.3(c) and (d).  The Technology Based Effluent Limits for Total Mercury (Outfall 002) are based on the requirements of 40 CFR 125.3(a) , 40 CFR 122.44(a)(1); 40 CFR 125.3(c) and (d).  The Whole Effluent Toxicity limit (Outfall 002) is based on the requirements of 15A NCAC 2B .0500. PROPOSED CHANGES  The Seep Outfall 010 (Please see A. (8.)) and Seep Pollutant Analysis Special Condition (Please see A. (21.)) were added to the permit.  The Toe Drains Outfall 011 (Please see A. (9.) was added to the permit.  The Appendix A and Appendix B were added to the permit.  The turbidity limit was added to the permit (Outfall 002 and Outfall 011)to meet the state turbidity standard per 15A NCAC 2B .0211(3) (k).  The pH limits were added to the permit (Outfalls 002A and 002B) to meet the state pH standard per 15A NCAC 2B .0200.  The Technology Based Effluent Limits for Total Arsenic, Total Mercury, Total Selenium, and Nitrate/nitrite as N were added to the permit (Outfalls 010, and 011) and are based on the requirements of 40 CFR 125.3(a) , 40 CFR 122.44(a)(1); 40 CFR 125.3(c) and (d).  The Technology Based Effluent Limits for Total Arsenic, Total Selenium, and Nitrate/nitrite as N were added to the permit (Outfall 005) and are based on the requirements of 40 CFR 125.3(a) , 40 CFR 122.44(a)(1); 40 CFR 125.3(c) and (d).  The Technology Based Effluent Limits for Total Mercury were added to the permit (Outfall 002) and are based on the requirements of 40 CFR 125.3(a) , 40 CFR 122.44(a)(1); 40 CFR 125.3(c) and (d). NPDES Permit Fact Sheet NC0004979 Page 7 of 7  Monitoring for Chlorides was removed from the permit (Outfall 002) based on the results of Reasonable Potential Analysis.  The Monitoring Frequency for As, Se, and Total Mercury was reduced to Quarterly (Outfall 005) based on the results of Reasonable Potential Analysis.  Monitoring for TSS, COD, Total Cadmium, Total Chromium, Chlorides, Total Nickel, Total Silver, Total Zinc and Total Beryllium was removed from the permit (Outfall 005) based on the results of discharge evaluation.  Proposed federal regulations require electronic submittal of all discharge monitoring reports (DMRs) and specify that, if a state does not establish a system to receive such submittals, then permittees must submit DMRs electronically to the Environmental Protection Agency (EPA). The Division anticipates that these regulations will be adopted and is beginning implementation. The requirement to begin reporting discharge monitoring data electronically using the NC DWR’s Electronic Discharge Monitoring Report (eDMR) internet application has been added to the permit. (Please see Special Condition A. (22.)).  The Applicable State Law Special Condition was added to the permit to meet the requirements of Senate Bill 729 (Coal Ash Management Act, Please see Special Condition A. (23.)). PROPOSED SCHEDULE Draft Permit to Public Notice: March 8, 2015 (est.) Permit Scheduled to Issue: July 27, 2015 (est.) STATE CONTACT If you have any questions on any of the above information or on the attached permit, please contact Sergei Chernikov at (919) 807-6386 or sergei.chernikov@ncdenr.gov.