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HomeMy WebLinkAboutNC0004774_Major Modification_20191028 00 STATE 9 ROY COOPER Governor -42 li MICHAEL S.REGAN Secretory *A°`a"olVIO* LINDA CULPEPPER NORTH CAROLINA Director Environmental Quality October 28, 2019 Mr. Paul Draovitch, Senior Vice President Environmental, Health and Safety Duke Energy Progress, LLC Mail Code EC13K P.O. Box 1006 Charlotte, North Carolina 28201-1006 Subject: Draft NPDES Major Modification Permit NC0004774 Buck Combined Cycle Station Rowan County Facility Class I Dear Mr. Draovitch: The Division has received your request to eliminate temperature requirements for the coal-fired units due to the conversion to the natural gas. The request has been granted. Enclosed with this letter are 4 pages that include necessary modifications. Please review these pages to ensure thorough understanding of the conditions and requirements they contain. The draft permit modification contains the following significant,changes from your current permit: • Elimination of the temperature requirements for Outfall 001A and Outfall 006. Please provide any comments you have regarding the draft permit to this office by December 2, 2019. At this time, the Division is also publishing a notice in the newspapers of general circulation in Rowan County, inviting public comment on the Draft Modification. Following the 30-day comment period, we will review all pertinent comments received and take appropriate action on the permit modification. DEQej North Carolina Department of Environmental Quality I Division of Water Resources 512 North Salisbury Street I 1617Mail Service Center I Raleigh.North Carolina 2 769 9-1617 919.707.3601 If you have any questions about the NPDES permit process, please contact me at the following e-mail address: sergei.chernikov ,iJncdenr.gov, or telephone number: 919- 707-3606. Sin�ce_rely, 1 ergei Chernikov, Ph.D. Environmental Engineer III Complex NPDES Permitting Unit cc: Central Files NPDES Files EPA Region IV (e-copy) Mooresville Regional Office/Water Quality (e-copy) Mooresville Regional Office/PWS (e-copy) WSS/Aquatic Toxicology Unit (e-copy) Page 2 of 2 Permit NC0004774 A.(3.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 001A- CTCC Operations) [15A NCAC 02B .0400 et seq.,02B .0500 et seq.] a. During the period beginning upon both elimination of all remaining waste flows from the Buck Steam Station and diversion of CTCC Plant flows to Outfall 001A and lasting until diversion of CTCC Plant flows to Outfall 006 or until permit expiration,whichever is first,the Permittee is authorized to discharge wastewaters,as described herein,from Outfall 001A.Such discharges shall be limited and monitored by the Permittee as specified below: EFFLUENT LIMITATIONS MONITORING REQUIREMENTS PARAMETER Monthly Daily Measurement Sample Sample Average Maximum Frequency Type Location' Flow,MGD Daily Pump logs Effluent or similar readings pH >_ 6.0 and _< 9.0 standard units Daily2 Grab Effluent Temperature 35°C(95°F) Daily Grab Effluent Temperature Daily Grab Intake and Effluent Total Nitrogen, mg/L3 Monthly Grab Effluent Total Phosphorus, mg/L Monthly Grab Effluent Total Suspended Solids 23.0 mg/L 74.0 mg/L 2/Month Grab Effluent Oil and Grease 11.0 mg/L 15.0 mg/L 2/Month Grab Effluent Total Residual Chlorine 4 28.0 pg/L 2/Month Grab Effluent Free Available Chlorine 4 200 pg/L 500 pg/L 2/Month Grab Effluent Total Hardness, mg/L as CaCO3 2/Month Grab Effluent Total Arsenic, pg/L 5 Quarterly Grab Effluent Total Selenium, pg/L 5 Quarterly Grab Effluent Total Mercury, ng/L 5 Quarterly Grab Effluent Total Aluminum, mg/L 5 Quarterly Grab Effluent Total Antimony, pg/L 5 Quarterly Grab Effluent Total Chromium 5-6 200 pg/L 200 pg/L 2/Month Grab Effluent Total Copper 5 Quarterly Grab Effluent Total Nickel, pg/L 5 Quarterly Grab Effluent Total Zinc 5.6 1,000 pg/L 1,000 pg/L 2/Month Grab Effluent Total Fluoride, mg/L Quarterly Grab Effluent Chloroform, pg/L ' Quarterly Grab Effluent Chronic Toxicity 8 P/F @ 0.1% Quarterly Grab Effluent The 126 priority pollutants except Total Chromium and No detectable amount Annually Grab Effluent Total Zinc 5,6 Footnotes: 1. Effluent sampling shall be conducted below the final treatment unit and prior to mixing with any other waste streams. Intake means the facility's raw water intake. 2. Upon completing at least three consecutive months of daily pH readings,the Permittee may request that pH monitoring be reduced to Weekly.Such request should demonstrate to the Division's satisfaction that the results of weekly monitoring will adequately represent the measure and variability of effluent pH. If a request was approved for Outfall 001A,the approval may be extended to Outfall 006 without requiring resubmittal of the request. (Footnotes continue on next page) 5 Permit NC0004774 A.(3.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (cont.) Footnotes(cont.): 3. Total Nitrogen=NO2-N+NO3-N+TKN 4. The Division shall consider all effluent TRC values reported below 50 µg/L to be in compliance with the permit. However,the permittee shall continue to record and submit all values reported by a North Carolina certified laboratory(including field certified),even if these values fall below 50 µg/L. Neither free available chlorine(FAC) nor TRC may be discharged from any single generating unit for more than two hours in any single day,and not more than one unit in the plant may discharge FAC or TRC,unless the discharger demonstrates to the Division that the unit(s)cannot operate at or below this level of chlorination. 5. See Special Condition C.(6.)Metals Analyses. 6. See Special Condition C.(7.)Priority Pollutant Limitations and Analysis. 7. See paragraph(g)of this condition. 8. See Special Condition C.(8.)Chronic Toxicity Permit Limit. b. Authorized waste flows from the CTCC Plant are potable,service,and process water treatment wastes;floor drain wastes;cooling tower blowdown;heat recovery steam generator(HRSG)and auxiliary boiler blowdowns;and stormwater flows draining to the sump.Such waste flows shall not pass through the ash settling pond prior to discharge. c. There shall be no discharge of metal cleaning waste or chemical metal cleaning waste. d. There shall be no discharge of floating solids or visible foam in other than trace amounts. e. This condition is not intended to authorize concurrent waste discharges through both Outfalls 001A and 006 except to the extent necessary to make an orderly transition to the newer outfall.The Permittee shall cease discharge at Outfall OO1A as soon as practical after bringing Outfall 006 online. f. Unless it has already done so in accordance with Special Condition A.(2.) (e),the Permittee shall analyze a representative sample of the CTCC Plant Wastewater Sump discharge and submit a complete and accurate EPA Application Form 2C for the sump discharge no later than the date established per Condition A.(2.)(e). g. If chloroform monitoring was waived in accordance with conditions A.(2.) (a)and(f),the monitoring requirement specified in paragraph(a)of this condition is waived for the remainder of the permit term.If the initial chloroform analysis is conducted while this condition is effective,and if the initial analysis does not yield a reportable concentration of chloroform(PQL<2.0 pg/L),chloroform monitoring specified in paragraph(a)of this condition is waived for the remainder of the permit term. h. The mixing zone for thermal discharges from the Buck facility is defined as that portion of the Yadkin River(High Rock Lake)extending from the Buck Combined Cycle Station water intake to High Rock Lake Dam.The thermal variance and mixing zone terminate on expiration of this permit.The Director may reopen the permit to extend or modify the variance based on the findings of the Thermal Mixing Zone Study(see Special Condition C.(13.))or other new information. i. When High Rock Lake,as measured at the intake of the Buck Combined Cycle Station,is drawn down 10 feet or greater,the Permittee shall on a daily average basis ensure that the minimum unheated daily average stream flow does not fall below one third of the 7-day 10-year low flow(7Q10). j. The Permittee shall notify the Division in writing no later than seven calendar days prior to diversion of CTCC Plant flows to Outfall 006;see Special Condition C.(2.)Notifications and Submittals. 6 Permit NC0004774 A.(4.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 006-CTCC Operations) [15A NCAC 02B .0400 et seq.,02B .0500 et seq.] a. During the period beginning upon both elimination of all remaining waste flows from the Buck Steam Station and diversion of CTCC Plant flows to Outfall 006 and lasting until permit expiration,the Permittee is authorized to discharge wastewaters,as described herein,from Outfall 006.Such discharges shall be limited and monitored by the Permittee as specified below: EFFLUENT LIMITATIONS MONITORING REQUIREMENTS PARAMETER Monthly Daily Measurement Sample Sample Average Maximum Frequency Type Location' Flow, MGD Daily Pump logs Effluent or similar readings pH >_ 6.0 and <_ 9.0 standard units Daily2 Grab Effluent Temperature 35°C(95°F) Daily Grab Effluent Temperature Daily Grab Intake Effluentd Total Nitrogen, mg/L3 Monthly Grab Effluent Total Phosphorus, mg/L Monthly Grab Effluent Total Suspended Solids 23.0 mg/L 74.0 mg/L 2/Month Grab Effluent Oil and Grease 11.0 mg/L 15.0 mg/L 2/Month Grab Effluent Total Residual Chlorine 4 28.0 pg/L 2/Month Grab Effluent Free Available Chlorine 4 200 pg/L 500 pg/L 2/Month Grab Effluent Total Hardness, mg/L as CaCO3 2/Month Grab Effluent Total Arsenic, pg/L 5 Quarterly Grab Effluent Total Selenium, pg/L 5 Quarterly Grab Effluent Total Mercury, ng/L 5 Quarterly Grab Effluent Total Aluminum, mg/L 5 Quarterly Grab Effluent Total Antimony, pg/L 5 Quarterly Grab Effluent Total Chromium 5'6 200 pg/L 200 pg/L 2/Month Grab Effluent Total Copper 5 Quarterly Grab Effluent Total Nickel, pg/L 5 Quarterly Grab Effluent Total Zinc 5.6 1,000 pg/L 1,000 pg/L 2/Month Grab Effluent Total Fluoride, mg/L Quarterly Grab Effluent Chloroform, pg/L ' Quarterly Grab Effluent Chronic Toxicity 8 P/F @ 0.1% Quarterly Grab Effluent The 126 priority pollutants except Total Chromium and No detectable amount Annually Grab Effluent Total Zinc 5,6 Footnotes: 1. Effluent sampling shall be conducted below the final treatment unit and prior to mixing with any other waste streams.Intake means the facility's raw water intake. 2. Upon completing at least three consecutive months of daily pH readings,the Permittee may request that pH monitoring be reduced to Weekly.Such request should demonstrate to the Division's satisfaction that the results of weekly monitoring will adequately represent the measure and variability of effluent pH.If a request was approved for Outfall OO1A,the approval may be extended to Outfall 006 without requiring resubmittal of the request. (Footnotes continue on next page.) 7 Permit NC0004774 A.(4.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (cont.) Footnotes(cont): 3. Total Nitrogen=NO2-N+NO3-N+TKN 4. The Division shall consider all effluent TRC values reported below 50 µg/L to be in compliance with the permit. However,the permittee shall continue to record and submit all values reported by a North Carolina certified laboratory(including field certified),even if these values fall below 50 µg/L. Neither free available chlorine(FAC) nor TRC may be discharged from any single generating unit for more than two hours in any single day,and not more than one unit in the plant may discharge FAC or TRC,unless the discharger demonstrates to the Division that the unit(s)cannot operate at or below this level of chlorination. 5. See Special Condition C.(6.)Metals Analyses. 6. See Special Condition C.(7.)Priority Pollutant Limitations and Analysis. 7. See paragraph(g)of this condition. 8. See Special Condition C.(8.)Chronic Toxicity Permit Limit. b. Authorized waste flows from the CTCC Plant are potable,service,and process water treatment wastes;floor drain wastes;cooling tower blowdown;heat recovery steam generator (HRSG)and auxiliary boiler blowdowns;and stormwater flows draining to the sump. Such waste flows shall not pass through the ash settling pond prior to discharge. c. There shall be no discharge of metal cleaning waste or chemical metal cleaning waste. d. There shall be no discharge of floatingsolids or visible foam in other than trace e amounts. e. Conditions A.(3.)and A.(4.)are not intended to authorize concurrent waste discharges through both Outfalls 001A and 006 except as necessary to make an orderly transition to the new outfall.The Permittee shall cease discharge at Outfall 001A as soon as practical after bringing Outfall 006 online. f. Unless it has already done so in accordance with Special Condition A.(2.) (e)or A.(3.) (f),the Permittee shall analyze a representative sample of the CTCC Plant Wastewater Sump discharge and submit a complete and accurate EPA Application Form 2C for the sump discharge no later than the date established in condition A.(2.)(e). g. If chloroform monitoring was waived in accordance with conditions A.(2.)a)and (f)or conditions A.(4.)(a)and (g),the monitoring requirement specified in paragraph(a)of this condition is waived for the remainder of the permit term. If the initial chloroform analysis is conducted while this condition is effective,and if the initial analysis does not yield a reportable concentration of chloroform(PQL<2.0 pg/L),chloroform monitoring specified in paragraph(a)is waived for the remainder of the permit term. h. The mixing zone for thermal discharges from the Buck facility is defined as that portion of the Yadkin River(High Rock Lake)extending from the Buck Combined Cycle Station water intake to High Rock Lake Dam. The thermal variance and mixing zone terminate on expiration of this permit.The Director may reopen the permit to extend or modify the variance based on the findings of the Thermal Mixing Zone Study(see Special Condition C.(13.))or other new information. i. When High Rock Lake,as measured at the intake of the Buck Combined Cycle Station,is drawn down 10 feet or greater,the Permittee shall on a daily average basis ensure that the minimum unheated daily average stream flow does not fall below one third of the 7-day 10-year low flow(7Q10). j. The Permittee shall notify the Division in writing no later than seven calendar days following the closure of Outfall 001A to confirm its closure;see Special Condition C.(2.)Notifications and Submittals. 8