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HomeMy WebLinkAboutNC0003425_Fact Sheet_20170105 (3)DEPARTEMENT OF ENVIRONMENTAL QUALITY DIVISION OF WATER RESOURCES FACT SHEET FOR NPDES PERMIT DEVELOPMENT NPDES No. NC0003425 Facility Information Applicant/Facility Name: Duke Energy Progress/Roxboro Steam Electric Generating Plant Applicant Address: 1700 Dunnaway Rd., Semora, NC 27343 Facility Address: 1700 Dunnaway Rd., Semora, NC 27343 Permitted Flow Not limited Type of Waste: 99.8 % Industrial, 0.2% - domestic Facility/Permit Status: Existing/Renewal County: Person Miscellaneous Receiving Stream: Hyco Reservoir Stream Classification: WS-V, B Subbasin: 03-02-05 303(d) Listed?: No Drainage Area (mi2): Lake Primary SIC Code: 4911 Summer 7Q10 (cfs) 0 Regional Office: RRO 30Q2 (cfs): 0 Quad Olive Hill Average Flow (cfs): 0 Permit Writer: Teresa Rodriguez IWC (%): 100% Date: 1/5/2017 Summary The Roxboro Steam Electric Plant is an electric generating facility that uses steam turbine generation (via four coal-fired units with a total net capacity of 2558 MW). Units No. 1 and 2 (385 MWe and 670 MWe, respectively) use condensers as cooling devices. Units No. 3 and 4 (707MWe and 700 MWe, respectively) use cooling towers as cooling devices. The facility has three existing cooling water intake structures (CWISs). The source water for CWISs No.1 and 2 is the Hyco Reservoir. The source water for CWIS no. 4 is the site's cooling canal. The facility total intake is approximately 1,114 MGD. The facility discharges to subbasin 030205 in the Roanoke River Basin. Discharges are mostly industrial, with a very small domestic flow (internal Outfall 008) piped to the on -site ash pond. Discharges from the ash pond (internal Outfall 002), once -through cooling water and FGD treatment system (internal outfall 010) are discharged to the Discharge Canal (outfall 003). The Discharge Canal and Coal Pile Runoff (outfall 006) both discharge to Hyco Reservoir. The Hyco Reservoir is a 17.6 km2 waterbody constructed in 1963 by CP&L to serve as a cooling water source. The receiving waterbody is class WS-V; B. The facility is located in the Lower Piedmont area of the state, the applicable state water quality temperature standard is 32'C (89.6' F). This facility is subject to EPA effluent guideline limits per 40 CFR 423 - Steam Electric Power Generating Point Source Category which were amended November 3, 2015. The facility is also subject to the Cooling Water Intake Structures Rules (40 CFR 125) effective October 14, 2014. The intake flow is > 125 MGD. The facility operates five internal outfalls and two outfalls to Hyco Reservoir. Duke requested the addition of three new outfalls on the permit; two to reflect the future treatment systems for the low volume wastes as the ash basin will be closed and one for seeps and stormwater. Description of existing outfalls: • Outfall 003 - Heated Discharge Canal to Hyco Reservoir. The discharge canal combines all internal outfalls (002, 005, 008, 009, 010) before discharging to Hyco Reservoir. In addition, once- NPDES PERMIT FACT SHEET Page 2 Roxboro Steam Electric Plant NPDES No. NC00003425 through cooling water from condensers for units 1,2, and 3, once -through cooling water from heat exchangers, seepage from ash pond, and stormwater runoff from plant drainage areas are discharged to the discharge canal. Outfall 006 - Coal Pile Runoff discharges directly to Hyco Reservoir. Coal pile runoff wastewaters include runoff from the coal pile, limestone pile and gypsum pile, truck wheel wash area and coal handling areas. Treatment is accomplished by neutralization, sedimentation and equalization. Internal Outfall 002 - Ash Pond discharging to the discharge canal. The ash pond receives wastewater from the following source: • Bottom ash transport waters • Silo wash water • Ash landfill leachate and runoff (this landfill receives CCR from Mayo and Roxboro plants) • Dry -ash handling system wash water • Blowdown from Unit 4 cooling tower • Coal mill rejects and pyrites • Sewage treatment plant effluent • Low volume waste consisting of boiler blowdown, equipment maintenance cleaning wastewaters, RO reject wastewater and floor drains. Low volume wastes are treated by neutralization. • Emergency overflow from FGD system blowdown. • Internal Outfall 005 - Cooling tower blowdown from Unit 4. • Internal Outfall 008 - Treated domestic wastewater. The treatment system consists of a screen, communitor, surge tank, aeration tank, clarifier, chlorine contact chamber and sludge holding tank. A new package plant will be installed to replace the existing plant. • Internal Outfall 009 - Chemical metal cleaning waste. Wastewaters from cleaning of the boilers is generated every five to eight years. Every three to five years wastewaters are generated from cleaning the heat exchangers. The wastewaters generated can be treated by evaporation or by neutralization and precipitation. • Internal Outfall 010 - Flue Gas Desulfurization (FGD) treatment system discharging to the discharge canal. The scrubber system removes SOx by mixing flue gas with a limestone slurry. The blowdown from the scrubber is discharged to a gypsum settling pond system then to a bioreactor which utilizes microorganisms to reduce soluble contaminants to insoluble forms (under anaerobic conditions) that then precipitate from solution. Wastewater is discharged to the ash pond effluent channel. An emergency overflow from the FGD system blowdown discharges to the ash pond. Proposed Outfalls: Outfall 001 (Seeps) - Stormwater and four seeps from the ash landfill flow to the intake canal through a common outfall. This outfall was at one time permitted in a previous permit as outfall 001 and will be reinstated to monitor the seeps. Internal Outfalls 012A and 012B - Low volume waste and other wastewaters. Duke will build two basin treatment systems to treat wastewaters that now go to the ash basin. 2 NPDES PERMIT FACT SHEET Roxboro Steam Electric Plant Page 3 NPDES No. NC00003425 CWA 316 (W 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. Temperature Mixing Zone - Outfall 003 The facility is located in the Lower Piedmont area of the state, the applicable state water quality temperature standard is 32°C (89.6° F). The authorized temperature mixing zone for outfall 003 includes the North Hyco Arm downstream of NC Hwy 57, the main body of Hyco Reservoir downstream of the confluence of the Cobbs Creek Arm and the North Hyco Arm and the entire after bay lake. USGS data at the after bay monitoring station (USGS Station 02077303) was reviewed for the period of January 2011 to April 2016. Data shows that the temperature water quality standard was not exceeded for this period. Maximum temperature recorded was 30.5°C. Instream Monitoring The permit requires monitoring of Hyco Reservoir in accordance to the Biological Monitoring Program as approved by the Division. Based on the Divisions review of the reports the fish community is comparable to other piedmont reservoirs and no problems were noted. DATA REVIEW/PERMIT REOUIREMENTS Internal Outfall 002 - Ash Pond This outfall is subject to the Effluent Limitations Guidelines (ELG) in Table 1. Table 1. ELG Outfall 002 (Prior to November 1, 2018) Pollutant Daily Maximum Monthly Average ELG TSS 100 mg/1 30 mg/1 40 CFR 423.12 (b) (4) Oil & Grease 20 mg/1 15 mg/1 40 CFR 423.12 (b) (4) The current permit requires monitoring for flow and total selenium, limits for Oil & Grease and TSS. A summary of DMR data for the period of January 2011 to January 2016 is included in Table 2. There have been no violations of permit limits or conditions. Table 2. DMR Summary Outfall 002 Parameter Average 9r Maximum Minimum Flow 10.8 MGD 48.3 MGD 3.1 MGD TSS 5 mg/1 21 mg/1 < 2.5 mg/1 Total Selenium 14.6 µg/1 68.8 µg/1 < 10 µg/1 O&G <5mg/1 13.5mg/1 <5mg/1 Table 3. Monitoring Requirements/Proposed Changes Outfall 002 Parameter Monitoring requirements Chan es Basis Flow Monitor No changes 15A NCAC 2B.0505 TSS 30 mg/1 monthly aver 100 mg/1 daily max No changes 40 CFR 423.12(b)(4) Oil & Grease 15 mg/1 monthly aver 20 mg/1 daily max No Changes 40 CFR 423.12(b)(4) Total Selenium Monthly monitoring No changes Pollutant of concern Turbidity, pH No requirement Monitor Pollutant of concern for dewatering/ decanting NPDES PERMIT FACT SHEET Page 4 Roxboro Steam Electric Plant NPDES No. NC00003425 Schedule of Compliance Fly Ash/Bottom Ash: As per 40 CFR 423.13 (k) (1) (i) bottom ash transport water shall not be discharged, compliance with this section shall be as soon as possible beginning on November 1, 2018, but no later than December 31, 2023. Duke utilizes wet bottom ash transport system. Duke is proposing to install a remote mechanical drag chain system. Design of the system is expected to be completed in 8 months, followed by procurement in 12 months. Construction is expected to be completed in 13 months. Duke proposes a 16 month window to optimize the system at full load and additional 6 months for potential permitting delays. Consideration was given to the fact that Duke will be undertaking design, procurement and installation activities in multiple facilities simultaneously. Duke will meet the no discharge of bottom ash requirement by April 30, 2021. Fly ash transport water is no longer discharged therefore Duke meets the compliance date of November 1, 2018. Internal Outfall 002 - Dewatering To meet the requirements of the Coal Ash Management Act of 2014, the facility needs to dewater two ash ponds by removing the interstitial water and excavate the ash to deposit it in landfills. The facility's highest discharge rate from the dewatering process will be 2 MGD. The facility submitted data for the standing surface water in the ash ponds, interstitial water in the ash, and interstitial ash water that was treated by filters of various sizes. The following pollutants were detected at concentrations higher than the water quality standards: selenium, arsenic and molybdenum. A new effluent and monitoring sheet is included in the permit for the ash pond dewatering phase. As this is an internal outfall the water quality standards are not applied. Monitoring will be required for selenium, arsenic, molybdenum, antimony and copper. 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. Outfall 003 - Discharge Canal (Combined outfallsj DMR/Compliance Review Data were reviewed for the period of January 2011 to March 2016. There have been no violations of permit limits or conditions. Table 4. DMR Summary Outfall 003 Parameter Average Maximum Minimum Flow (MGD) 840 1130 6.9 TRC Not discharged TP (mg/1) < 0.036 < 0.05 < 0.05 TN (mg/1) 1 0.68 1.08 0.44 Temperature (°C) 29 41 13°C Total Arsenic (µg/1) 6.2 17.1 < 2.8 pH (SU) 7.34 8 6.38 Toxicity Testing (003): Current Requirement: Acute P/F at 90%, February, May, August, November. Proposed Requirement: Acute P/F at 90%, February, May, August, November. The facility passed 21 tests out of 21 tests performed for the period of January 2011 to January 2016. rd NPDES PERMIT FACT SHEET Roxboro Steam Electric Plant Page 5 NPDES No. NC00003425 Reasonable Potential Analysis Outfall 003: 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 003. For the purposes of the RPA, the background concentrations for all parameters were assumed to be below detection level. The RPA uses 95% probability level and 95% confidence basis in accordance with the EPA Guidance entitled "Technical Support Document for Water Quality -based Toxics Control." With the approval of the Triennial Review (2007-2014) of the NC Water Quality Standards by the Environmental Management Commission (EMC) in 2014 and US -EPA (with some exceptions) on April 6, 2016, the NPDES Permitting Unit is required to implement the new dissolved metal standards in all permits public noticed after April 6, 2016. The RPA included evaluation of dissolved metals' standards, utilizing measured hardness value of 100 mg/L CaCO3 for hardness -dependent metals. A reasonable potential analysis was conducted for arsenic, copper, nickel, selenium, strontium, thallium, chlorides and zinc. Arsenic data used for the RPA was collected between 2011 and 2016. Data for the remaining parameters was from a special study for the period of March 2010 to August 2011. Based on this analysis, the following permitting actions are proposed for this permit: • 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: Arsenic, selenium, chloride. • 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: copper, nickel, strontium, and zinc. • Limit: The following parameter will receive a limit since it demonstrated reasonable potential to exceed the applicable water quality standards/criteria: thallium. Mercury Evaluation Outfall 003: A mercury evaluation was conducted in accordance with the permitting guidance developed for the implementation of the statewide Mercury TMDL to determine the need for a limit and Mercury Minimization Plan (MMP). Monitoring for mercury is not required for outfall 003 but mercury data was collected during a special study during the period of March 2010 to August 2011. The water quality based effluent limitation (WQBEL) for mercury is 12 ng/l. The technology based effluent limit (TBEL) is 47 ng/l. None of the annual averages exceeds the WQBEL or TBEL, no limit is required. See the attached mercury evaluation spreadsheet. Table 5. Mercury Evaluation 2010 2011 # of Samples 20 16 Annual Average, ng/L 3.6 4.4 Maximum Value, ng/L 7.63 6.92 TBEL, n /L 47 WQBEL, ng/L 12.0 NPDES PERMIT FACT SHEET Page 6 Table 6. Monitoring Requirements/Proposed Changes Outfall 003 Roxboro Steam Electric Plant NPDES No. NC00003425 Parameter Monitoring Changes Basis requirements/Limits Flow Monitor No changes 15A NCAC 2B.0505 TRC 200 µg/l Modified limit to 28 µg State WQ standards, 15A NCAC instantaneous max /1 daily max 2B .0200. The water quality standard is more stringent than the effluent guidelines limit. TP Monitor No changes 15A NCAC 2B .0500 TN Monitor No changes 15A NCAC 2B .0500 Temperature Monitor No changes Approved Mixing zone Total Arsenic Monitor No changes Based on results from RPA, Predicted concentration greater than 50% of allowable. Total Selenium No requirement Quarterly monitoring Based on results from RPA, Predicted concentration greater than 50% of allowable. Total Thallium No requirement 0.24 µg/l Daily max Based on results from RPA. limit 0.24 µg/l Monthly Max Chloride No requirement Quarterly monitoring Based on results from RPA, Predicted concentration greater than 50% of allowable. pH 6 to 9 SU No changes State WQ standards, 15A NCAC 2B .0200 Acute toxicity P/F 90% No changes State WQ standards, 15A NCAC 2B .0200 Internal Outfall 005 - Cooling Tower Blowdown from Unit 4 This outfall is subject to the ELGs in Table 7. Table 7. ELG Outfall 005 Pollutant Dail Maximum I Monthl Avera e pH 6 to 9 SU 40 CFR 423.12 (b) (1) Free Available Chlorine 0.5 mg/l 0.2 mg/l 40 CFR 423.12 (d) (1) 126 Pollutants No detectable amounts 40 CFR 423.13 (d) (1) Total Chromium 0.2 mg/l 0.2 mg/l 40 CFR 423.13 (d) (1) Total Zinc 1.0 mg/l 1.0 mg/l 40 CFR 423.13 (d) (1) The permit includes monitoring for flow and Total Residual Chlorine (TRC), limits for Free Available Chlorine, Total Chromium, Total Zinc and 126 priority pollutants. Special condition A. (14) in the permit doesn't allow the discharge of the cooling tower blowdown to the discharge canal, it has to be discharged to the ash pond. With the modifications planned to the site and the future closure of the existing ash pond Duke will like to have the option to discharge the blowdown to the discharge canal. This will continue to be an internal outfall subject to the same limits under 40 CFR 423. The limits apply before it comingles with any other waste stream so there is no change in limits or other permit conditions by allowing the cooling tower blowdown to discharge into the discharge canal. J NPDES PERMIT FACT SHEET Roxboro Steam Electric Plant Page 7 NPDES No. NC00003425 DMR/Compliance Review: Data were reviewed for the period of January 2011 to January 2016. There have been no violations of permit limits or conditions. Flow was the only parameter monitored at this outfall since the facility did not chlorinate or added chromium or zinc for maintenance activities. Flow is reported as 7.2 MGD on a daily basis. Table 8. Monitoring Requirements/Proposed Changes Outfall 005 Parameter Monitoring Requirements/Limits Changes Basis Flow Monitor No changes 15A NCAC 2B.0505 Free available 500 µg/l daily max No changes 40 CFR 423.13 (d)(1) chlorine 200 µg/l monthly average Total Residual Chlorine Monitoring No changes 40 CFR 423.13 (d) (2) Total chromium 200 µg/l daily max No changes 40 CFR 423.13 (d)(1) 200 µg/l monthly average Total Zinc 1.0 mg/l daily max No changes 40 CFR 423.13 (d)(1) 1.0 mg/l monthly average The 126 priority pollutants No detectable amount No changes 40 CFR 423.13 (d)(1) Outfall 006 - Coal Pile Runoff This outfall is subject to the ELG in Table 9. Table 9. ELG Outfall 006 Pollutant Daily Maximum Monthly Average ELG TSS 50 mg/l 40 CFR 423.12 (b) (9) pH 6 to 9 SU 40 CFR 423.12 (b) (1) DMR/Compliance Review: Data were reviewed for the period of January 2008 to March 2013. There have been no violations of permit limits or conditions. Table 10. DMR Summary Outfall 006 Parameter Average Maximum Minimum Flow (MGD) 0.23 0.05 0.002 TSS (Mg/ 1) 2.6 76.6 < 2.5 H (SU) 7.39 8.9 6.04 Priority Pollutant Scan: The application included the results of one scan. Selenium was detected above the water quality standard. 7 NPDES PERMIT FACT SHEET Page 8 Table 11. Monitoring Requirements/Proposed Changes Outfall 006 Roxboro Steam Electric Plant NPDES No. NC00003425 Parameter Monitoring Changes Basis requirements/Limits Flow Monitor No changes 15A NCAC 213.05 TSS 50 mg/1 instantaneous Added Monthly average 40 CFR 423.12(b)(9), max limit of 30 mg/1 40 CFR 122.45 pH 6 to 9 SU No changes 40 CFR 423.12 (b) (1) Total selenium No requirement 5.0 µg/1 Monthly Average RPA 56 µg/1 Daily Max Acute toxicity P/F 90% No changes g State WQ standards,15A NCAC 213.0200 Internal Outfall 008 - Domestic WWTP Table 12. DMR Review Outfall 008 Parameter Average Maximum Minimum Flow (MGD) 0.007 0.01 0.002 TSS (mg/1) 14.7 30 5 pH (SU) 6.8 7.3 6.5 BOD (mg/1) 10.4 28 2.1 NH3N (mg/1) 0.8 1.6 < 0.1 Table 13. Monito ing Requirements/ Proosed Changes Outfall 008 Parameter Monitoring I requirements/Limits Changes Basis Flow 0.015 MGD Add effluent page WWTP will be upgraded during for 0.025 MGD this permit cycle TSS 30 mg/1 monthly No changes NPDES rules for secondary aver treatment of domestic 45 mg/1 daily max wastewater,15A 213.0400 pH 6 to 9 SU No changes State WQ standards,15A 213 .0200 BOD 30 mg/1 monthly No changes NPDES rules for secondary aver treatment of domestic 45 mg/1 daily max wastewater,15A 213.0400 Total ammonia Monitor No changes DWQ Policy Internal Outfall 009 - Chemical cleaning waste Table 14. Monitoring Requirements/Proposed Changes Outfall 009 Parameter Monitoring re uirements/Limits Changes Basis Flow Monitor No changes 15A NCAC 2B.0505 Total Copper 1.0 mg/1 monthly aver No changes 40 CFR 423.13 (e) 1.0 mg/1 daily max Total Iron 1.0 mg/1 monthly aver No changes 40 CFR 423.13 (e) 1.0 mg/1 daily max TSS 30 mg/1 monthly aver No changes 40 CFR 423.13 (e) 100 mg/1 daily max Oil & Grease 15 mg/1 monthly aver No changes 40 CFR 423.13 (e) 20 mg/1 daily max N. NPDES PERMIT FACT SHEET Page 9 Roxboro Steam Electric Plant NPDES No. NC00003425 Internal Outfall 010 - FGD This outfall is subject to the Effluent Limitations Guidelines (ELG) in Table 15. These are new limitations promulgated November 3, 2015. Table 15. ELG Outfall 010 Pollutant Daily Maximum K I Monthly Average ELG pH 6 to 9 SU 40 CFR 423.12 (b) (1) TSS 100 mg/1 30 mg/1 40 CFR 423.12 (b) (11) Oil and grease 20 mg/1 15 mg/1 40 CFR 423.12 (b) (11) Total Arsenic 11 µg/1 8 µg/1 40 CFR 423.13 (g) (1) (i) Total Mercury 788 n /1 356 n /1 40 CFR 423.13 () (1) (i) Total Selenium 23 µ /1 12 µ /1 40 CFR 423.13 (g) (1) (i) Nitrate/nitrite 17 mg/1 4.4 mg/1 40 CFR 423.13 (g) (1) (i) The current permit includes monitoring for flow, total beryllium, total mercury, total antimony, total selenium, total silver and total vanadium. Table 16 includes a summary of DMR data for the period of January 2011 to January 2016. There have been no violations of permit limits or conditions. Table 16. DMR Summary Outfall 010 Parameter Average Maximum Minimum Flow (MGD) 0.84 1.77 0.01 Total Beryllium (µg/1) 3.9 10 < 1 Total Mercury (µg/1) 1.08 9.6 < 1 Total Selenium (µg/1) 102 712 < 50 Total Silver (µg/1) 6 8.4 < 5 Total Antimony (µ /1) 31 70 < 25 Total Vanadium (µg/1) < 25 < 25 < 5 Table 17. Monitoring Requirements/Proposed Changes Outfall 010 Parameter Monitoring I requirements/Limits Changes Basis Flow Monitor N o changes 7Remove 15A NCAC 2B.0505 Total Beryllium Monitor monitoring Internal outfall, not a parameter of concern. Total Vanadium Monitor Remove monitoring Internal outfall, not a parameter of concern. Total Antimony Monitor Remove monitoring Internal outfall, not a parameter of concern. Total Silver Monitor Remove monitoring Internal outfall, not a parameter of concern. Total Arsenic No monitoring 11 µg/1 daily max and 8 µg/1 monthly average 40 CFR 423.13 (g) (1) (i) Total Selenium Monitor 23 µg/1 daily max and 12 µg/1 monthly 40 CFR 423.13 (g) (1) (i) average Nitrate/Nitrite No monitoring 17 mg/1 daily max and 4.4 mg/1 monthly 40 CFR 423.13 (g) (1) (i) average Total Mercury Monitoring 788 ng/1 daily max and 356 ng/1 monthly 40 CFR 423.13 (g) (1) (i) average. b NPDES PERMIT FACT SHEET Roxboro Steam Electric Plant Page 10 NPDES No. NC00003425 Schedule of Compliance FGD: 40 CFR 423 establishes compliance dates for the new limitations. Permittee must meet limits as soon as possible beginning on November 1, 2018 but no later than December 31, 2023. Duke utilizes a biological treatment system to treat FGD wastewaters. Duke anticipates that it will be required to install physical/chemical treatment followed by selenium reduction technology to meet the FGD guidelines. Evaluation of new technologies and design of the system is expected to take 30 months. The evaluation phase includes evaluation of existing treatment system, flow optimization, siting of the new system within the plant, selection of technology and permitting. Procurement is expected to be completed in 20 months, construction and tie-in expected to be completed in 16 months considering that tie-in has to be done during outages. Startup and optimization under all expected operating conditions is estimated for 15 months. An additional 6 months is included in the schedule for potential permitting delays. Duke will meet the FGD ELG by December 31, 2023. As the new treatment system will be placed in operation and the old pond may still discharge until it is decommissioned. A new outfall is included in the permit for the new system. Provosed Outfalls: Seeps: The facility identified 16 unpermitted seeps. The following seeps from the ash landfill discharge through a common outfall to Hyco Reservoir at the intake canal: S-09, S-10, S-11, and S-12. The outfall used to be the authorized outfall for the effluent from the old ash basin. The seep flow into a concrete culvert and channel that leads to the intake canal. An effluent channel determination was conducted by the Raleigh Regional Office staff on December 15, 2016. Seeps S-01, S-02, S-03, S-04, S-05, S-06, S-07, S-08, S-14, S-18, and S-19 are internal to outfall 003. Seeps 1 through 7 are chimney drains from the ash basin dam. The flow from the combined seeps account for less than 0.0005 % of the total discharge. These are considered de -minimum discharges and will be included in the authorized wastewaters discharging through outfall 003. Outfall 001 Four seeps discharge to the intake canal at Hyco Reservoir where former Outfall 001 used to discharged. The Division will reinstate outfall 001 to monitor the discharge from the seeps and stormwater. The following seeps discharge through outfall 001: S-09, S-10, S-11, and S-12. RPA A RPA was conducted for proposed outfall 001. RPA was conducted for total arsenic, cadmium, chlorides, total chromium, total copper, total lead, total mercury, total molybdenum, total nickel, selenium, total zinc, antimony, sulfate and total thallium. As a result of the RPA limits are required for the following parameters: fluoride, arsenic, sulfate and selenium. Mercury Mercury data was collected for the seeps during 2014 and 2015. 2014 data was collected using method 245 which has a higher detection limit that 1631. Data for 2015 was used to evaluate a need for a limit. The annual average was 5.2 ng/l, no limit will be implemented. In addition to the limits described above all the seep outfalls will have monitoring requirements for fluoride, total mercury, total barium, total iron, total manganese, total zinc, total arsenic, total cadmium, total chromium, total copper, total lead, total nickel, and total selenium, and limits as described in Table 18. 10 NPDES PERMIT FACT SHEET Page 11 Table 18. Outfall 001 Proposed Limits/Monitoring: Roxboro Steam Electric Plant NPDES No. NC00003425 Parameter Monitoring requirements/Limits Basis Flow Monitor 15A NCAC 2B.0505 pH 6 to 9 SU State WQ standards, 15A 2B .0200 Total copper, total antimony, Monitor Coal ash parameters of concern. total lead, total zinc, total barium, total iron, total manganese, total nickel, total mercury, chlorides Fluoride Limit -1.8 mg/l RPA Total Arsenic Limit -10 µg/l RPA Total Selenium Limits 5 µg/l Monthly Average RPA 56 µg/l Daily Max Sulfates Limit - 250 mg/l (Monthly average RPA & daily max) TDS, Hardness, Conductivity Monitor Parameters of concern Acute toxicity Quarterly Limit State WQ standards, 15A NCAC 2B .0200 Low volume Waste Treatment Systems: Two new treatment systems will be installed to treat wastewaters currently delivered to the ash basin. Low volume wastes, metal cleaning wastes, stormwater, and other miscellaneous wastes that are routed to the ash basin will be rerouted to new treatment systems. Duke proposes two separate treatment systems. The new outfalls will be designated as outfall 012A and outfall 012B. The overflow from the 012B basin will be designated as outfall 012C. Duke estimated that design, construction and start up of the new treatment system will be completed within 30 months of permit issuance. Internal Outfall 012A - treatment system for the landfill leachate, silo wash water, contact and non - contact storm water and discharging to the discharge canal. Table 19. Outfall 012A Proposed Limits/Monitoring: Parameter Monitoring Basis ff requirements/Limits Flow Monitor 15A NCAC 2B.0505 Total Suspended Solids 30 mg/l Monthly Average 40 CFR 423.12 (b)(3) 100 mg/l Daily Max Oil & Grease 15 mg/l Monthly Average 40 CFR 423.12 (b)(3) 20 mg/l Daily max Internal Outfall 012B - treatment system for plant low volume wastes, FGD treatment system effluent, domestic waste treatment system, anhydrous ammonia emergency discharge, metal cleaning wastes, stormwater runoff, and cooling tower blowdown. The discharge from outfall 012B will go to the discharge canal. 11 NPDES PERMIT FACT SHEET Page 12 Table 20. Outfall 012B Proposed Limits/Monitoring: Roxboro Steam Electric Plant NPDES No. NC00003425 Parameter Monitoring requirements/Limits Basis Flow Monitor 15A NCAC 2B.0505 Total Suspended Solids 30 mg/1 Monthly Average 100 mg/1 Daily Max 40 CFR 423.12 (b)(3) Oil & Grease 15 mg/1 Monthly Average 20 mg/1 Daily max 40 CFR 423.12 (b)(3) Ammonia Monitor Monitor during emergency discharge of anh drous ammonia Emergency Outfall 012C - The basin discharging through 012B will have an emergency overflow Table 21. Outfall 012C Proposed Limits/Monitoring: Parameter Monitoring requirements/Limits Basis Flow Monitor 15A NCAC 2B.0505 Total Suspended Solids 30 mg/1 Monthly Average 100 mg/1 Daily Max 40 CFR 423.12 (b)(3) Oil & Grease 15 mg/1 Monthly Average 20 mg/1 Daily max 40 CFR 423.12 (b)(3) Ammonia Monitor Monitor during emergency discharge of anhydrous ammonia Arsenic Monitor Parameter of concern Mercury Monitor Parameter of concern Selenium Monitor Parameter of concern Nitrate/ nitrite Monitor Parameter of concern Copper Monitor Parameter of concern Iron Monitor Parameter of concern Public Notice/Public Hearing The first draft of this permit was public noticed on August 30, 2016. A public hearing was held on October 4, 2016. A second public notice is being published since the first notice went to a newspaper out of the area. Summary of permit modifications: • A separate effluent page for the dewatering of the ash ponds (Outfall 002) was added to the permit. • Outfall 001 was reinstated to monitor discharge of seeps and stormwater. • A new internal outfall (Outfall 011) was added to the permit to monitor the discharge from the proposed FGD treatment system. • Special Condition A. (14) that prohibited the discharge of cooling tower blowdown from outfall 005 to the discharge canal was eliminated from the permit. • A special condition was added to describe Section 316(b) requirements for submittal of applicable information. • A special condition was added to the permit to require an Ash Pond Closure Plan. • A Special Condition was added to the permit to require compliance with Senate Bill 729 (Coal Ash Management Act). • Attachment 1 entitled "Groundwater Monitoring Plan' was added to the permit. 12 NPDES PERMIT FACT SHEET Roxboro Steam Electric Plant Page 13 NPDES No. NC00003425 • Attachment 2 entitled "Plan for Identification of New Discharges' was added to the permit. Summary of modifications to the first draft permit: • Condition A. (1) Effluent Limitations and Monitoring Requirements for seeps - monitoring requirements were updated to include the same list of parameters monitored for seeps in other Duke permits. • Condition A. (2) Effluent Limitations and Monitoring Requirements for the ash basin - monitoring was added for arsenic, molybdenum, and chromium. In addition, a statement was added with the requirement to use physical/chemical treatment during dewatering. • Condition A. (2) & A. (3) Effluent Limitations and Monitoring Requirements for the ash basin - Statement regarding no discharge of fly ash was modified to read that no discharge of fly ash is allowed. The statement pertaining to the schedule of compliance with the ELG for zero discharge of bottom ash was corrected to read April 30, 2021 instead of November 1, 2018. • Condition A. (10) & A. (11) Effluent Limitations and Monitoring Requirements for the FGD - footnote 3 was corrected to read December 31, 2023. • Turbidity sampling was eliminated from internal outfall 002. Turbidity monitoring is included at outfall 003. • Supplement to cover sheet was modified to include flows that were not listed and add proposed outfalls and outfalls. • Condition A. (6) Effluent Limitations and Monitoring Requirements outfall 006: o Oil and Grease limits were added since it receives truck wash waters. o The RPA was revised and limits for total selenium were added. • Condition A. (4) Effluent Limitations and Monitoring Requirements for outfall 003: o Footnote 4 was modified to include a statement regarding the addition of temperature limits if the facility is not in compliance with the temperature water quality standard. o Reporting of the temperature at the afterbay station was added to the monitoring requirements for outfall 003, reporting of temperature at 4C, 4D was eliminated. o The RPA was revised and limits for thallium were added. • Condition A. (17)- temperature reporting requirements were modified. • A. (8) Effluent Limitations and Monitoring Requirements for outfall 008 - monitoring requirements were modified to require quarterly monitoring for one year after the new plant start operations, annual monitoring is required after one year of quarterly monitoring. • Two new internal outfalls (Outfall 012A and 012B) were added to the permit for the two proposed retention basins for the treatment of low volume wastes that are now sent to the ash basin. Duke will build two separate wastewater treatment systems to handle the wastes that go to the ash pond. These ponds will be in different locations in the site and will require each a separate outfall into the effluent channel. • Outfall 012C was added to the permit for the emergency overflow of the proposed lined retention basin discharging through outfall 012B. • A table including a list of all the seeps locations was added to Condition A. (14). Public Notice schedule: Draft permit to Public Notice: January 22, 2017 Permit Scheduled to issue: March 10, 2017 STATE CONTACT If you have any questions on any of the above information or on the attached permit, please contact Teresa Rodriguez at (919) 807-6387. NAME: DA 13 NPDES PERMIT FACT SHEET Page 14 Amendment to Fact Sheet - March 2017 Roxboro Steam Electric Plant NPDES No. NC00003425 Comments were received from Duke Energy, Sierra Club and the Southern Environmental Law Center Duke Energy Comments: 1. Include extracted groundwater as contributing flow to 003 and 001. - The groundwater flow was not included because it is not an existing source and it has not been characterized. The groundwater treatment system is not in operation and is not expected to commence for approximately three years. When the groundwater system is defined and a schedule for operation is known the permit can be modified. 2. List retention basis (012) as potential flow path for cooling tower blowdown (Outfall 005) - the retention basin (012B) is listed as potential flow path for outfall 005 3. List retention basin as potential flow path for domestic wastewater (Outfall 008) - the retention basin (012B) is listed as potential flow path for outfall 008. 4. List retention basin for potential flow path for landfill leachate - its listed on 12 A, does it goes to 12A or 1213? 5. Modify WET sampling frequency from monthly to quarterly for outfall 001- the sampling frequency will not be modified, all the outfall for seeps receive monthly sampling for WET. 6. Footnote for outfall 001 related to fly ash discharges should read "no fly ash should be discharged after November 1, 2018 - the footnote was corrected. 7. Remove pH limitations from internal outfalls 002 - the pH limit was removed 8. Clarify that flow limit of 2.0 MGD only applies for interstitial water treated through physical/chemical treatment - 9. Add language on special condition A.(5) to include that the cooling water can be discharged through the retention basin or the discharge canal - the flow path is already included in the supplement to cover sheet, it will not be included in the outfall description in condition A.(5). 10. Remove monthly average limit for selenium in outfall 006, this outfall is not continuous and is associated with precipitation events only - ? 11. Add the following language to Condition A.(15): "All previously identified seeps from this facility are contributing flows to outfalls 003 and 001. There are no seeps that discharge directly to jurisdictional waters". List all the seeps that are tributary to outfall 003 - 12. Clarify language in condition A.(19) that temperature readings from the afterbay will be obtained from the existing USGS Gaging station and that a malfunction of the station will not be considered a violation of the permit - proposed language: "Temperature readings from the afterbay shall be obtained from the existing USGS station (02077303). In case where the permittee experiences equipment problems and is unable to obtain daily temperatures from the monitoring station temperature monitoring must be reestablished within five working days." Comments received from public: SELC: 14