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HomeMy WebLinkAboutNC0004979_Correspondence_20210728 (6)ROY COOPER Governor ELIZABETH S. BISER Secretary S. DANIEL SMITH Director NORTH CAROLINA Environmental Quality July 26, 2021 Ms. Jessica Bednarcik, Senior Vice President Environmental, Health and Safety Duke Energy Carolinas, LLC Mail Code EC13K P.O. Box 1006 Charlotte, North Carolina 28201-1006 Dear Ms. Bednarcik: Subject: Final NPDES Major Modification Permit NC0004979 Allen Steam Station Gaston County Facility Class I The Division of Water Resources is forwarding herewith the Final Major Modification for Roxboro Steam Electric Generating Plant. This modification is issued pursuant to the requirements of North Carolina General Statute 143-215.1 and the Memorandum of Agreement between North Carolina and the U.S. Environmental Protection Agency dated October 15, 2007 (or as subsequently amended). The Final Major Modification contains the following significant changes from your Draft Permit: • Early retirement exemption has been postponed and earlier FGD limits have been re- instated until Duke submits the Notice of Planned Participation (Internal Outfall 005). • The ELG re -opener clause was added to the permit (Internal Outfall 005). The Final Major Modification maintains the following significant changes contained in the Draft Permit: • The Bottom Ash Purge was added to the list of waste streams discharged to the Retention Basin. • The wastewater generated by the dewatering process and extracted groundwater were added to the to the Retention Basin to achieve timely closure of the Ash Pond and provide greater operational flexibility. • The flow limit for dewatering operations was increased from 1.0 MGD to 3.0 MGD to achieve timely closure of the Ash Pond. • The Upstream and Downstream monitoring locations were moved to monitor discharge from the Retention Basin. North Carolina Department of Environmental Quality I Division of Water Resources 512 North Salisbury Street 11617 Mali Service Center I Raleigh, North Carolina 27699-1617 919,707.9000 • The pH limits at the Internal Outfall 005 were removed to be consistent with the requirements in 40 CFR 423. • The Technology Based Effluent Limits for TSS and Oil and Grease were added to the permit (Outfall 005) based on the latest update to the 40 CFR 423. • The Annual Progress Report requirement was added to the permit (see Special Condition A. (19) based on the latest update to the 40 CFR 423. • The RPA for Retention Basin was conducted by adding the highest reported concentration of the contaminants in the interstitial wastewater. The flow volume was also increased from 3.3 MGD to 3.5 MGD based on the latest estimates that incorporate flor from the CCR landfill. The limits for As were added as a result of this RPA (Outfall 006). • The RPA for Ash Basin dewatering phase was conducted by increasing flow from 1.0 MGD to 3.0 MGD. No new limits were added as a result of this RPA (Outfall 002). • The Special Condition that requires electronic submittal of all discharge monitoring reports was changed based on the latest update to the NPDES Electronic Reporting Rule (See Special Condition A. (26.)). • The Toxicity Test Instream Waste Concentrations for dewatering and Retention basin have been adjusted (Outfall 002 dewatering and Outfall 006) to account for the increased flow volume. If any parts, measurement frequencies, or sampling requirements contained in this permit are unacceptable to you, you have the right to an adjudicatory hearing upon written request within thirty (30) days following receipt of this letter. This request must be in the form of a written petition, conforming to Chapter 150B of the North Carolina General Statutes, and filed with the office of Administrative Hearings, 6714 Mail Service Center, Raleigh, North Carolina 27699-6714. Unless such a demand is made, this permit shall be final and binding. Please note that this permit is not transferable except after notice to the Division. The Division may require modification or revocation and reissuance of the permit. This permit does not affect the legal requirements to obtain other permits which may be required by the Division of Water Resources or any other Federal, State, or Local governmental regulations. If you have any questions or need additional information, please contact Sergei Chernikov, telephone number (919) 707-3606 or email: sergei.chernikov@ncdenr.gov. cc: Central Files NPDES Files Mooresville Regional Office/Water Quality WSS/Aquatic Toxicology Unit (e-copy) EPA Region IV (e-copy) Sincerely, >f- S. Daniel Smith, Director Division of Water Resources ,D_EQV) North Carolina Department of Environmental Quality I Division of Water Resources 512 North Salisbury Street 11617 Mail Service Center I Raleigh. North Carolina 27699-1617 919.707.9000