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Home My WebLink AboutNC0004774_Permit Applcation- Update_20180309 etas DUKE Duke Energy Buck Combined Cycle ENERGY® 1385 Dukewlle Road Salisbury,NC 28146 March 9, 2018 Mr. Mike Templeton RECEIVED/DENR/DWR Environmental Engineer NC Division of Water Resources MAR 14 2018 1617 Mail Service Center Raleigh, NC 27699-1617 Water Resources Permitting Section Re: NPDES Wastewater Permit Application Update Duke Energy Carolinas, LLC. Buck Combined Cycle and Buck Steam Station Permit#: NC0004774 Rowan County Dear Mr. Templeton, Duke Energy Carolinas, LLC (Duke) submits the following update on the draft National Pollution Discharge Elimination System (NPDES) Permit for Buck Combined Cycle and Buck Steam Station. This update is in addition to the renewal application submitted February 26, 2016, and updates submitted August 31, 2016, and on December 6, 2017. This submittal provides additional details and clarifications and /or modification on specific provisions of the draft permit, as discussed during the recent meeting with Division staff on February 12, 2018. Duke Energy is formally requesting a 6 month compliance schedule for the new limits at NPDES Outfall 002 for the discharge of process wastewaters prior to the commencement of decanting and dewatering. During this time, Duke Energy will be rerouting process flows to outfall 006 and decant/dewatering flow to outfall 007. Duke requested an internal outfall for potential discharge of offline turbine wash sump water in the December 2017 submittal. Upon further evaluation, we will continue to pump and haul wastewaters contained in the blind sump and retract the request for an internal outfall. The December 2017 application described an incorrect description of the final outfall for 006 and 007 and should be disregarded. The corrected information is included in the attached narrative. Duke Energy appreciates NCDEQ's efforts to develop the Draft Permit, which addresses novel issues associated with surface impoundment decomnussioning and modifications required to facilitate those changes. Finalizing this wastewater permit is a critical step to advance that process. Duke Energy welcomes any further discussion on the Draft permit. Should you have any questions or require additional information, please contact Ms. Elizabeth Glenn at (980) 373- 0530 or at elizabeth.glenn@duke-energy corn. "I certify, under penalty of law, that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gather and evaluate the information submitted Based on my Inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief true, accurate, and complete I am aware that there are significant penalties for submitting false information, including the possibility of fines and imprisonment for knowing violations " Sincerely, Henry A. Botkins, Jr. General Manager Buck Combined Cycle Enclosures NPDES Supplemental Information for Buck Steam Station / Combined Cycle NPDES Permit # NC0004774 March 2018 Buck NPDES application update NC0004774 Rowan County Page 14 Requested Final Wastewater Outfalls — 006 & 007 Outfall 006 will be a new discharge and the final, main process wastewater discharge for the Buck CTCC facility. Please reference Attachment 1—Process Flow Diagram. Final discharge inputs include cooling tower blowdown, treated oil/water separator effluent, reverse osmosis, and reject water. Outfall 007 will be a new discharge for the decanting and dewatering phase of the ash basin complex. This outfall, once permitted and commissioned, will redirect flows from current permitted Outfall 002. Chemical Metal Cleaning Waste Currently, all metal cleaning waste from the CTCC Turbine Wash Blind Sump is collected and disposed of off-site. Buck CTCC will continue to collect metal cleaning waste in the blind sump for off-site disposal in-lieu of ultimately discharging to surface waters. Beneficiation Stormwater Designs for the Buck Beneficiation Facility are still in progress. Current proposals outline a closed-loop system, removing contact water from potential stormwater discharges. Any stormwater exiting the Beneficiation Facility will be non-contact stormwater and handled under the Industrial Stormwater Permitting process. If contact water cannot be recycled through the Beneficiation process, these flows will be directed to the Buck CTCC wastewater system for discharge. Flows will typically be less than 0.005 MGD and will be evaluated before combining with the CTCC wastewater system. The December 2017 update contains wash water data from an existing Beneficiation Facility. Proposed Wastewater Holding Basin Buck CTCC requests a future holding/settling basin for potential equalization and treatment. This basin will be located east of the CTCC facility, please reference Attachment 2—Proposed Holding Basin Aerial. The lined basin will be approximately 4 acres, 6 feet deep, and a Buck NPDES application update NC0004774 Rowan County Page 15 capacity of 10 million gallons. Future potential inputs would include all flows from the CTCC wastewater sump. Treatment options would include coagulants, flocculants, and pH control as needed to meet surface water quality standards. Seeps /AOWs S-09 is the final outfall from the engineered seeps at the Buck site The contributing flow to S- 09 are S-11, an engineered seep and S-17, a riprap toe drainage area. Outfall 109 in the current draft permit will represent S-09. Buck NPDES application update NC0004774 Rowan County Page 16 Attachement 1 Wastewater Flow Schematic March 2018 NPDES application update Buck Steam Station / Combined Cycle NC0004774 . - Wastewater Source Flows Buck Steam Station and Combined Cycle Station n Steam Station NPDES Wastewater Flow Schematic n Combined Cycle 1.) 0.58 MGD/400 gpm Cooling Tower BD 2.) 0.007 MGD/5 gpm 0/W Separator 3.) 0.014 MGD/ 10 gpm UF Backwash > Floor Drains } Stormwater > h Yadkin 4.) 0.022 MGD/ RO Reject Possible Future Reroute / 18 gpmUndetermined Outfall 5.) 0.62 MGD/433 gpm Outfall 006 Overflow Plant Sump ► Yard Sump ► Yadkin > ► Outfall 002A I, Potable Water -Alit Site Proposed Reroute(Option 1) ♦ Offsite Users Transport ►> Evaporation > Softener Backwash Well ► Softener 1 r' Potable Septic Ash Basin Water Users System I ►> Yadkin > ►> Evaporation&Drift > o Outfall 002 o • T ► Blowdown ► 12 IP. Main Cooling cc Seeps(Variable) Tower De Chlorination I o ► 0 • 1 2 * Yadkin Condenser • + Current Outfall 007 I ► Wastewater s Yadkin Service Water 1 ) • Oil/Water Yadkin Users J ► Separator 2 Sump Future Planned Route Outfall 006 Evaporation A A A s &Drift ►> Oil Off-site > 3 HRSG Blowdown Iv t ) Tanks , Intake J Chiller 1 4 Cooling ir Service Water/ ► Ultra Filter ► Reverse ► Ion Exchange ► Heat Recovery Vent Losses I---0Clarifier I- ► Filter --► Clearwell ► Fierwater Osmosis Steam Generators • Storage Tanks • 4 Emergency Firewater Condenser Sludge oi Hotwell Thickener Filter Press ► Solids Off-site Disposal > Turbine Floor Drain < ► Online Wash Evaporation > Clarifier ---10Maintenance -0> Solids Off-site Disposal > T Drain Turbine Turbine Wash Offline Water Sump ----4> Off-site Disposal > Buck NPDES application update NC0004774 Rowan County Page 18 Attachment 2 Proposed Holding Basin Aerial March 2018 NPDES application update Buck Steam Station / Combined Cycle NC0004774 Buck NPDES application update NC0004774 Rowan County Page I 9 Proposed Basin % ./ Legend Write a descnption for your map Buck Steam Station Duke Energy .,: „mgr Wastewater Header ` W. 111 • 1 ' • • r .'. • kyt 9 Ix ' �° er Header ie . 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