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NCS000554_Buck CTCC Draft Permit Fact Sheet_20180502DEQ/DEMLR FACT SHEET FOR NPDES STORMWATER PERMIT DEVELOPMENT NPDES No. NCS000554 Facility Information Applicant/Facility Name: Duke Energy Progress, LLC - Buck Combustion Turbine Combined Cycle (CTCC) Station Applicant Address: P.O. Box 1006, Mail Code EC13K; Charlotte, North Carolina 28201 Facility Address: 1385 Dukeville Road; Salisbury, North Carolina 28146 Permitted Flow: N/A Stormwater Discharges Only) Industrial Activities: Primary SIC Code: 4911 - Electric Services Permit Status: New NPDES Stormwater Permit County: Rowan Count Miscellaneous Receiving Stream: Yadkin River (High Rock Lake) Regional Office: Mooresville Stream Classification: WS -V State Grid / USGS Quad: F15Sw 303(d) Listed? Cu, chlor a, turbidity Fish tissue Hg/PCB statewide Permit Writer: B. Georgoulias Sub -basin: 03-07-04 Date: May 2, 2018 • Facility Location: Lat. 35'42'30"N Long. 80° 22'40" W BACKGROUND Duke Energy's Buck Combustion Turbine Combined Cycle (CTCC) Station is a relatively new natural gas-fired 620 MW electric generation station (built in 2011) in Rowan County, three miles east of Spencer. This facility is located on the same property as the Buck Steam Station coal-fired power plant that is being decommissioned. The Buck CTCC is approximately 2,000 feet south and upland of the older Buck Steam Station and northwest of the ash settling basin. The plant discharges stormwater through one outfall, SW001, from the site's stormwater detention pond located west of the CTCC plant. In addition to NPDES wastewater discharge permit NC0004774 (wastewater discharge into Buck Steam Station's ash basin), the facility also holds TV037886T27 (air permit) and NCD043678929 (RCRA hazardous waste permit). The facility is subject to federal requirements of 40 CFR §423 - Steam Electric Power Generation. This category is subject to federal NPDES stormwater discharge permit requirements per 40 CFR §122.26 (b)(14)(vii). The company originally applied to the Stormwater Permitting Program (SPP) for an NPDES stormwater discharge permit for this CTCC facility in September 2011 (prior to its construction completion). A staff report request with a draft permit was sent to the Mooresville Regional Office, Division of Water Resources (formerly Water Quality), in January 2012 and received back in the Central Office with comments on February 7, 2012. The original draft permit was publically noticed on March 6, 2012. The SPP received comments from the company on March 20, 2012. The permit Fact Sheet NPDES Stormwater Permit NCS000554 Page 1 was never finalized and issued, however, because of unresolved discussions between NCDEQ (formerly NCDENR) and Duke Energy regarding NPDES discharge permits for coal-fired power plants. This new proposed draft stormwater permit resumes the process begun by the company's original NPDES discharge application to the Department in 2011, but it is based on an updated individual permit structure, more recent site activity information, and a more recent visit by NCDEQ staff in November 2015. This facility discharges to the Yadkin River (High Rock Lake). According to the 2014 Integrated Report, this segment of the Yadkin River (Upper portion of High Rock Lake) is impaired for copper. Just downstream of the discharge, High Rock Lake is impaired for turbidity and chlorophyll a. All these waters are impaired because of fish tissue PCB and mercury levels (a statewide issue). The current Basinwide Plan (from 2008) recommends continued support for Best Management Practices (BMPs) implementation, sediment and erosion control local programs, and local stormwater control ordinances. High Rock Lake was added to the Division of Water Resource's Nutrient Criteria Development Plan, and nutrient -related impairments will be addressed through future state management strategy rule-making efforts. The NC Natural Heritage Program Data Explorer (accessed January 29, 2016) indicated the presence of a freshwater mussel with State Threatened status (Eastern Lampmussel) within a one - mile radius of the Buck Steam Station and CTCC combined boundary. During a site visit in November 2015, Stormwater Permitting Program (SPP) staff identified two additional manholes (Manhole #1 and Manhole #2) south of the facility's cooling tower structure that are tied into Buck CTCC's stormwater collection system that received unidentified flows. In addition, it was unclear whether a riprap channel between these two manholes was connected to the toe drain system of Buck Steam Station's ash settling basin. The Division emphasized that any potential for wastewater drainage into the stormwater system at this site must be eliminated because the proposed permit only authorizes stormwater discharges through a single outfall point, SW001. The company provided additional information on April 18, 2016, and June 30, 2016 that addressed these concerns: • An engineer confirmed that none of the toe drains from the ash basins drains into the riprap ditch in question. • The area draining to the riprap ditch had been the staging area for offices during the construction of this plant and is currently a graveled area on top of a hill. The plant confirmed that the area is not used for industrial activities. • The company already provided information that the receiving pipes for Manhole #2 had been sealed (per responses to DEQ questions received on January 11, 2016), but Manhole #1 was still receiving water from somewhere. Plant personnel suspected that flow into the receiving terra cotta pipes for that manhole may be from a spring encountered under the cooling tower but had been unable to confirm the source. The company therefore made plans to reroute flow of that manhole out of Buck CTCC's stormwater system but did not have a firm timeline to complete this project, which would require a dam safety permit. • On June 30, 2016, a company representative confirmed that Manhole #1 has been rerouted and no longer flowed into the CTCC's stormwater system. Instead it now flows to the same area as AOW 5-09, a seep that will be permitted under Buck Steam Station's wastewater permit. Fact Sheet NPDES Stormwater Permit NCS000554 Page 2 WHY THIS FACILITY IS SUBIECT TO A PERMIT Federal NPDES regulations define stormwater discharge associated with industrial activity in 40 CFR §122.26 (b)(14) as: "the discharge from any conveyance that is used for collecting and conveying storm water and that is directly related to manufacturing, processing or raw materials storage areas at an industrial plant. The term does not include discharges from facilities or activities excluded from the NPDES program under this part 122. For the categories of industries identified in this section, the term includes, but is not limited to, storm water discharges from industrial plant yards; immediate access roads and rail lines used or traveled by carriers of raw materials, manufactured products, waste material, or by-products used or created by the facility; material handling sites; refuse sites; sites used for the application or disposal of process waste waters (as defined at part 401 of this chapter); sites used for the storage and maintenance of material handling equipment; sites used for residual treatment, storage, or disposal; shipping and receiving areas; manufacturing buildings; storage areas (including tank farms) for raw materials, and intermediate and final products; and areas where industrial activity has taken place in the past and significant materials remain and are exposed to storm water. For the purposes of this paragraph, material handling activities include storage, loading and unloading, transportation, or conveyance of any raw material, intermediate product, final product, by-product or waste product. The term excludes areas located on plant lands separate from the plant's industrial activities, such as office buildings and accompanying parking lots as long as the drainage from the excluded areas is not mixed with storm water drained from the above described areas." This facility's activity falls under Category (vii) of these regulations, steam electric power generating facilities. While documentation for EPA's Multi -Sector Permit (MSGP) in 2008 clarified the federal agency's interpretation that natural gas-fired combined cycle systems (such as Buck's CTCC plant) would not require permit coverage unless it were dual fuel capable (including back-up or auxiliary fuel capability), the company is not pursuing this "natural gas -only turbine exemption" from NPDES permitting at this time. NC DEQ has also concluded that NPDES stormwater permit coverage is appropriate, especially given the discovery of connections between the Buck Steam Station property and Buck CTCC that were not identified in the original application (found during a site visit in November 2015). PROPOSED MONITORING FOR STORMWATER DISCHARGES No sampling results were submitted with EPA Form 2F as part of the NPDES stormwater permit application in 2011 because the site had not yet been built. Monitoring parameters in this draft permit are based on potential pollutants in the drainage area indicated on the submitted application. According to the application, the drainage area includes two gas turbine buildings, one steam turbine building, one water treatment building, one auxiliary boiler building, one cooling tower structure, two chiller buildings, one administration building, a raw water treatment facility, several large transformers, a power distribution center (PDC), an emergency diesel generator, two large water tanks, one large ammonia tank, an oil/water separator, and the station consolidated wastewater sump. Note that during the November 2015 site visit, there was some discussion as to whether the PDC was included in this permit because it does not drain to the stormwater detention pond and is under different management. The original application included the following information about the industrial materials and potential stormwater contaminants on the site: Most chemical storage, if exposed, to be located within concrete containments. All transformer containments discharge to the oil/water separator (wastewater discharge). Fact Sheet NPDES Stormwater Permit NCS000554 Page 3 • All open containments (including tanker unloading stations) discharge directly to the consolidated wastewater sump. Most covered containments will be non -discharge containments. • Lube oils, diesel fuel, and mineral oil would be present at the site. • Ammonia to be stored at the site (20,000 gal tank on western side of facility, inside containment draining to sump; 300 gal tank inside Steam Turbine Building). • Raw water treatment facility chemicals stored under common shed inside containment. Chemicals include sodium hypochlorite, ferric sulfate, and caustic. • Cooling tower has adjacent chemical feed skid with chemical storage under shed; unloading pad is sloped and curbed, and drains to sump. Chemicals include sodium hypochlorite, dispersant, micro biocide, and general water treatment (not specified). Below is a table of the proposed monitoring for the single outfall at the Buck CTCC site. The outfall SWO01 ultimately discharges to the Yadkin River (High Rock Lake). Stormwater Discharge Outfall (SDO) Monitoring SW001 Drains entire site through Stormwater Detention Pond Total Suspended Solids (TSS) Semi-annual monitoring. BASIS: Potential pollutant from drainage area and detention pond BMP effectiveness indicator. Also related to turbidity, a parameter of concern for this segment. Non -polar Oil & Grease (Method Semi-annual monitoring. BASIS: Potential pollutant from 1664 SGT -HEM)* lubricants and diesel fuel stored on site; Method 1664 SGT -HEM targetspetroleum-based 0&G*. Total Ammonia as Nitrogen Semi-annual monitoring. BASIS: Potential pollutant from large (NH3-N) ammonia storage tank and loading/unloading areas. Exempt if DEQ determines storage and spill prevention measures for ammonia are sufficient to limit risk of pollutant discharge. Monitoring exemption expires i si ni scants ill occurs. Total Nitrogen (TN) Semi-annual monitoring. BASIS: Potential pollutant from ammonia storage and a nutrient sensitive watershed (High Rock Lake). Exempt if DEQ determines storage and spill prevention measures for ammonia are sufficient to limit risk of pollutant discharge. Monitoring exemption expires i si ni icants ill occurs. pH Semi-annual monitoring. BASIS: Rapid pollutant indicator for the nature of chemicals stored on site (caustic, acids, etc.) and important to interpreting toxicity potential of metals or ammonia. Copper Semi-annual monitoring. BASIS: Receiving waters are impaired for copper; potential wastewater contribution from previously unidentified ash basin toe drain connection (to be removed before permit finalized). *Note - This method is not the same as the more expensive GC analyses commonly used to measure Total Petroleum Hydrocarbons (TPH) and isolates petroleum-based oils, rather than capturing vegetable-based oils or animal fats that are not expected to be here. Even though some diesel fuel may be lost in the solvent extraction step of Method 1664 (SGT -HEM), the quantity of diesel in the emergency generator is smaller than the other oils and confined to the double -walled container. There is significant aqueous ammonia storage at this facility. Any spills from the smaller tank inside the steam turbine building would drain to the oil/water separator and then into the ash settling basin at Buck Steam Station (permitted under a separate NPDES wastewater permit.) The original application stated that spills from the 20,000 -gallon tank outside would drain to the wastewater sump; however, after review of piping diagrams, plant personnel determined that secondary containment from that tank instead drains to the stormwater retention basin, along with the ammonia unloading area and transfer pump skid. Appropriate tank level Fact Sheet NPDES Stormwater Permit NCS000554 Page 4 monitoring and secondary containment maintenance/inspection procedures (regular and prior to any stormwater release) should provide adequate measures to identify problems and prevent ammonia from being discharged in stormwater. The draft permit proposes ammonia and TN monitoring but allows for an exemption if the company provides information on: ammonia spill prevention procedures; how stormwater will be evaluated for ammonia contamination prior to release; and how the facility will handle or dispose of any contaminated stormwater. DEQ must approve the exemption in writing if measures are adequate to minimize risk of discharge. However, if a significant spill (reportable quantity) of ammonia occurs, the exemption expires. STORMWATER BENCHMARKS AND TIERED RESPONSE Rather than limits, North Carolina NPDES Stormwater permits contain benchmark concentrations. Stormwater benchmarks are numerical action levels for stormwater monitoring. Benchmarks are not effluent limits, and benchmark exceedances are not permit violations. Benchmarks provide facilities a tool for assessing the significance of pollutants in stormwater discharges and the effectiveness of best management practices (BMPs). Benchmark concentrations are intended as guidelines for the facility's development and implementation of the Stormwater Pollution Prevention Plan (SPPP). Benchmark exceedances require the permittee to increase monitoring, increase management actions, increase record keeping, and/or install stormwater BMPs in a tiered program. The permit establishes a tiered approach to specify actions the permittee must take in response to analytical results above benchmark concentrations (Part II, Section B.). The tiered structure of the permit provides the permittee and NC DEMLR wide flexibility to address issues that may arise with one or more parameters and/or outfalls. Metals and toxicant stormwater benchmarks are calculated to mimic acute water quality standards and with the guidance of NC's Division of Water Resources (DWR). NC DWR follows established federal procedures for calculating acute standards when developing the benchmarks. Just like the acute surface water standards, metals benchmarks normally reflect one half of the calculated Final Acute Value (the "1/a FAV"). In most cases, translation into total recoverable values is based on an assumed hardness of 25 mg/1 and a total suspended solids (TSS) concentration of 10 mg/1. Acute standards protect aquatic life from negative impacts of short-term exposure to higher levels of chemicals where the discharge enters a waterbody. The Stormwater Permitting Program applies this approach because of the ephemeral nature of rainfall events. Other benchmarks are based on a variety of sources. A summary of the benchmarks in the draft permit, and their basis, is below: Parameter Benchmark Basis Total Suspended Solids (TSS), National Urban Runoff Program (NURP) Study, mg/L 100 1983. Industrial sources expected to meet. Non -Polar Oil & Grease, EPA Review of other state's daily maximum benchmark Method 1664 (SGT -HEM), 1s concentration for this more targeted 0&G; NC WQ mg/L Standard that does not allow oil sheen in waters. NH3-N, (Total Ammonia as 1/z FAV @ pH of 8; EPA's 1999 Update of Ambient Nitrogen), mg/L 8.4 Water Quality Criteria for Ammonia (excludes salmonid species). Total Nitrogen, mg/L 30 Sum of DEQ Stormwater Benchmark values for Nitrate/Nitrite and Total Kjeldahl Nitrogen (TKN) pH 6-9 NC Water Quality Standard (Range) Copper (Cu), mg/L (Total) 0.010 Acute Aquatic Criterion, 1/z FAV Fact Sheet NPDES Stormwater Permit NCS000554 Page 5 STORMWATER POLLUTION PREVENTION PLAN The proposed permit conditions reflect the Environmental Protection Agency's (EPA) and North Carolina's pollution prevention approach to stormwater permitting. The Division's maintains that implementation of Best Management Practices (BMPs) and traditional stormwater management practices that control the source of pollutants meets the definition of Best Available Technology (BAT) and Best Conventional Pollutant Control Technology (BCT). The permit conditions are not numeric effluent limitations but are designed to be flexible requirements for implementing site- specific plans to minimize and control pollutants in stormwater discharges associated with the industrial activity. Title 40 Code of Federal Regulations (CFR) §122.44(k)(2) authorizes the use of BMPs in lieu of numeric effluent limitations in NPDES permits when the agency finds numeric effluent limitations to be infeasible. The agency may also impose BMP requirements which are "reasonably necessary" to carry out the purposes of the Act under the authority of 40 CFR 122.44(k)(3). The conditions proposed in this draft permit are included under the authority of both of these regulatory provisions. In essence, the pollution prevention and BMP requirements operate as limitations on effluent discharges that reflect the application of BAT/BCT. Determining specific BMPs that are appropriate for the site and activities are the permittee's responsibility, and the permit strives not to limit what BMPs can be used. The permittee should also refer to the BMPs described in both EPA's Multi -Sector Permit (MSGP) and Industrial Stormwater Fact Sheet for Steam Electric Power Generating Facilities (Sector 0) for guidance on pollution prevention measures. FLEXIBILITY IN TIER RESPONSES Tier Two actions (upon two consecutive benchmark exceedances at an outfall) proposed in this draft permit differs slightly from the Program's standard template and includes step 6. That step provides an opportunity for the permittee to propose an alternative monitoring plan for approval by the Region: Alternatively, in lieu of steps 2 and 3, the permittee may, after two consecutive exceedances exercise the option of contacting the DEMLR Regional Engineer as provided below in Tie T ree. e permittee as provided in Tier Three, including reduced or additional sampling parameters or frequency. If pursuing this option, the permittee may propose an alternative monitoring plan for approval by the Regional Engineer. The permit therefore allows the permittee to petition the Regional Office for monitoring changes sooner than Tier Three (upon any four benchmark exceedances) and gives guidance on one option to take. For example, the permitttee may request that only parameters over the benchmark be monitored more frequently (the default is for sampling of all parameters to increase). In this way, changes to the monitoring scheme for any outfall could be handled more effectively outside of a permit modification. OTHER PROPOSED REQUIREMENTS It is standard for Stormwater Pollution Prevention Plan (SPPP) requirements to include an annual certification that stormwater outfalls have been evaluated for the presence of non- stormwater discharges, and if any are identified, how those discharges are permitted or otherwise authorized. The draft permit requires this facility to submit the first certification to DEMLR no later than 90 days after the effective date of the permit (Part II, Section A.). Requirement to submit a request for permit modification if the facility identifies or creates any new outfalls, removes outfalls, or alters any drainage area that changes potential pollutants. Fact Sheet NPDES Stormwater Permit NCS000554 Page 6 Federal regulations will require electronic submittal of all discharge monitoring reports (DMRs). Permit provisions addressing this impending requirement is included in Part III, Section B (General Conditions), 3.e. Based on these regulations, the provision in the draft permit notes the permittee's obligation to begin reporting data electronically December 1, 2016 or when the agency's electronic reporting system is ready. (NC DEQ's eDMR system is not yet capable of receiving DMR data electronically for stormwater NPDES permits, but DEQ continues its work to expand the system to do so.) Standard conditions may be revised, and/or a Special Condition may be added into the permit to address the obligation to report electronically in more detail before the final permit is issued. PROPOSED SCHEDULE FOR PERMIT ISSUANCE: Draft Permit to Public Notice: May 2018 (est.) Permit Scheduled to Issue: August 15, 2018 (est.) STATE CONTACT: If you have any questions about any of the above information or the attached permit, please contact Bethany Georgoulias at (919) 807-6372 or bethany.georgoulias@ncdenr.gov. Fact Sheet NPDES Stormwater Permit NCS000554 Page 7