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Home My WebLink AboutNC0000396_Correspondence_20220209 (8)%'DUKE 4 ENERGY® PROGRESS FedEx tracking: 773483832087 File: 12520B April 20, 2021 Dr. Sergei Chernikov, PhD North Carolina Department of Environmental Quality Division of Water Resources 1617 Mail Service Center Raleigh, NC 27699-1617 Antonio D. Price, PE Plant General Manager Asheville Combined Cycle Station Duke Energy Progress ASVL PLT 146 Duke Energy Lane Arden, NC 28704 o: 828-650-0620 t 828-650-0701 antonio.price@duke-energy.com RECEIVED AFR 2 6 2021 NCDEQIDWRINPDES Subject: Asheville Steam Electric Generating Plant NPDES Permit NC0000396 Request for minor NPDES permit modification removing Outfalls OO1B and OO1D Dear Dr. Chernikov: The Asheville Steam Electric Generating Plant coal units retired in January of 2020 as planned and concurrent to the new natural gas combined cycle station completing commissioning. Decommissioning of the old units are well underway. A malfunction of the new oil water separator units, internal outfalls 001B and 001D, in February of 2020 has resulted in removing the equipment from normal service to investigate and resolve conditions that may have caused the incident. The investigation of the oil water separator malfunction revealed design criteria opportunities as well as process improvements. Some exterior stormwater containments were diverted to the industrial stormwater discharges and internal equipment drain piping was routed to the cooling water system. During the engineering evaluation of the system, the preferred design change was to route the discharge lines from the oil water separators to the side stream filter backwash sumps. This routing eliminates internal outfalls OO1B and 001D by recycling the flow back into the cooling water system and release through existing internal outfalls OO1A and OO1C. Outfalls OO1A, OO1B, OO1C and OO1D contain the same permit limits. This work was completed on April 19, 2021 in accordance with the written confirmation to proceed received from the North Carolinas Division of Water Resources. A minor NPDES permit modification is therefore requested to remove internal outfalls OO1B and OO1D from NPDES permit NC0000396. Enclosed are updated process flow diagrams for the system showing this change. Should you have questions or need additional information please contact Robert Wylie at 704 562-8258. Antonio D. Price, P.E. Asheville Plant Manager Attachments cc: Landon Davidson, DEQ, Asheville Regional Office Teresa Williams, Duke Energy Robert Wylie, Duke Energy Former Coal Plant Operation French Broad River Y Lake Julian Make Up Water Intake rSettling >ene Intake Structure Consumptive Loss T Flue Ga:, Desulfurization Public Water Supply Diesel Fire Pump Units 1 & 2 Condensers Clarifier Lake -Julian Circulating Water to Heat Exchanger AA Vender supplied water treatment Combustion Turbine Site Ash Sump Y Fire Protection System O M Lew �letome Waste Sources Potable and Sanitary c Storm -Water l4 Preheater Cleaning Water 1964 Ash Pond (Duck Pond) Public > Sewer System MSD Coal Pile Runoff 4- Ash Sluice Water Outfall 002 Evaporation in Boilers IL 1 Public Sewer System MSD Chemical Metal Cleaning Waste J Rim Ditch & Dam Seepage Evaporation Secondary Settling Basin A Gioundwatec Extraction racti P hys/<Shem WAS French Broad River Outfall 001 Attachmont C Process Flow Diagram Bake-€nercgy--Progrocs LLG French Broad River Make-up Water Settling Zone Lake Julian City of Asheville Public water Potable and Sanitary Systems 1 Public Sewer System (MSD) Intake Structure Evaporation Post Coal plant shutdown Jan 2021 Combined ► and Simple Cycle Plant Service Water Fire Protection System Power Block/Demo Industrial Storm Water Water truck dust suppression 1964 Ash Pond J BB Contact SW and Interstitial water Dam Seepage Outfall 101 Lined Retention Pond Onsite Physical/Chemical WTS FF Segregated clean SW (potentially) GG Note: Some process removed, no Change in discharge location/characteristics Combined and Simple Cycle Plant Secondary Settling Basin Groundwater Extraction French Broad River Outfall 001 AttachmentA — Process Flow Diagram Duke Energy Progress, LLC Asheville Steam Electric Plant Buncombe County March 2021 Lake Julian Intake Structure 2 Combined and Simple Cycle Combustion Turbine Plant 4 8 10 Existing Unit 3 and 4 Simple Cycle Demineral.zed Water Storage Tanks Simple Cycle CTG Water Wash Transfer Truck Unit 07/08 Raw \ Water Supply / Simple Cycle CTG Water Injection Evaporation 46 Ultrafiltration Backwash Strainer and ultrafiltration skids Atmosphere 6 OF Backwash Sump (Shared) Filter Press (Shared) 44 45 Service Water/Fire Water Tank 12 17 Service Water Users 16 38 Existing Simple Cycle Evap Cooling & Makeup Two -Pass Reverse Osmosis 14 Cooling Tower & Basin A 37 Sludge Thickener (1 per power block) 47 Transfer Truck t 43 Side -stream Filter Backwash Sump (1 per power block) 38 Atmosphere 11 Standby RO/Demin Trailers 13 22 HRSG Blowdown Tank/Sump v Side -St eam Filters per power b ock) 23 39 A Mixed -Bed Demineralizer 21 Equipment Drains Sump Existing Simple Cycle Stormwater Drains and lift station 38 15 } 20 24 HRSG 24 Sample Panel Unit 07/08 Cooling Tower Blowdown 001C 5 Unit 05/06 Cooling Tower Blowdown 001A 32 x 25 v 18 Demine alized Water Tanks 19 CTG Wash Water Unit 07/08 Oil Water Separator 001E v vy Waste Water Sump (Shared) 25 4 19 Existing Outfall 002 to Lake Julian CTG NOx Injection Transfer Truck Unit 7/8 TB / WTB drains sump Unit 05/06 Oil -Water Separator 001 D 26 Existing Ash pond LRB / WTS Secondary Settling Basin • Unit 5/6 TB drain sump French Broad River Outfal 1001 <Existing Fuel Oil Oil -Water Separator Existing Fuel Oil Area Stormwater Attachment A - Process Flow Diagram Duke Energy Progress, LLC Asheville Steam Electric Plant Buncombe County, March 2021