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Home My WebLink AboutNC0069841_Speculative Limits_20210713DocuSign Envelope ID: 3F6ECADA-70CD-4608-83A6-F42F5D0175E6 ROY COOPER. Governor ELIZABETH S. BISER Secretary S. DANIEL SMITH Director NORTH CAROLINA Environmental Quality July 13, 2021 Andrew Neff, P.E. Water and Wastewater Division Director Union County Public Works 4600 Goldmine Rd Monroe, NC 28112 Subject: Speculative Effluent Limits New Lower Crooked Creek WRF Union County Yadkin -Pee Dee River Basin Dear Mr. Neff: First, we appreciate the time and effort by our organization during this process. Based upon data and information provided by you, NCDEQ conducted a review and assessment utilizing the QUAL2K model and subsequent revisions from TetraTech which resulted in the required speculative limits evaluation. We want to note that NCDEQ is not in agreement in the interpretation of the application of the rules for less restrictive winter limits It is NCDEQ's position that rule 15A NCAC 2B .0404(b) allows for seasonal limits for existing facilities that are meeting the limits in summer but not consistently in winter, this precludes the application of the rule to new facilities. As the Lower Crooked Creek plant is a new facility, the clause for existing discharges in 15A NCAC 2B .0206(d) would not apply as well. With that said as requested this letter provides speculative effluent limits for 4.6 MGD and 8.2 MGD at a proposed new Lower Crooked Creek WRF. Please recognize that speculative limits may change based on future water quality initiatives, and it is highly recommended that the applicant verify the speculative limits with the Division's NPDES Unit prior to expending time and resources towards any engineering design work. Receiving Stream. Crooked Creek is located within the Yadkin -Pee Dee River Basin. Crooked Creek has a stream classification of C, and waters with this classification have a best usage for aquatic life propagation and maintenance of biological integrity, wildlife, secondary recreation and agriculture. Crooked Creek has a summer 7Q10 flow of 0.0 cfs, a winter 7Q10 flow of 0.4 cfs, a 30Q2 flow of 1.4 cfs, and an annual average flow of 24.0 cfs. Based upon an initial review of information available from the North Carolina Natural Heritage Program Online Map Viewer, there are not any Federally Listed threatened or endangered aquatic species identified within a 5-mile radius of the proposed discharge location. If there are any identified threatened/endangered species, it is recommended that the applicant discuss the NORT DE _ Department o! Environmental OuaINY 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 DocuSign Envelope ID: 3F6ECADA-70CD-4608-83A6-F42F5D0175E6 proposed project with the US Fish and Wildlife Service to determine whether the proposed discharge location might impact such species. Speculative Effluent Limits. Based on Division review of receiving stream conditions and water quality modeling results, speculative limits for the proposed expansion to 4.6 MGD and 8.2 MGD are presented in Tables 1 and 2, respectively. A complete evaluation of these limits and monitoring requirements for metals and other toxicants, as well as potential instream monitoring requirements, will be addressed upon receipt of a formal NPDES permit application. Some features of the speculative limit development include the following: • BOD/NH3 Limits. These limits are provided with the understanding that the Grassy Branch (NC0085812) and Crooked Creek #2 (NC0069841) plants will be decommissioned and their permits rescinded upon completion of each of the new plant's flow tiers respectively. Modeling used to support these speculative limits indicated potential for high pH stream values. The actual permit may use site -specific criteria to determine ammonia -nitrogen toxicity limits which may be lower than those in these tables. The EAA requirement listed below will need to include discussion of the removal of the existing plants and their effects on water quality parameters in the stream. TABLE 1. Speculative Limits for Lower Crooked Creek WRF (Proposed New at 4.6 MGD) Effluent Characteristic Effluent Limitations Monthly Average Weekly Average Daily Maximum Flow 4.6 MGD BOD5 5.0 mg/L 7.5 mg/L NH3 as N (summer) 1.0 mg/L 3.0 mg/L NH3 as N (winter) 1.9 mg/L 5.7 mg/L Dissolved Oxygen (daily average) > 6.0 mg/L TSS 30 mg/L 45 mg/L TRC 17 ug/1 Fecal coliform (geometric mean) 200/100 ml 400/100 ml Chronic Toxicity Pass/Fail (Quarterly test) 90% TABLE 2. Speculative Limits for Lower Crooked Creek WRF (Proposed New at 8.2 MGD) Effluent Characteristic Effluent Limitations Monthly Average Weekly Average Daily Maximum Flow 8.2 MGD BOD5 5.0 mg/L 7.5 mg/L NH3 as N (summer) 1.0 mg/L 3.0 mg/L NH3 as N (winter) 1.9 mg/L 5.7 mg/L Page 2 of 4 DocuSign Envelope ID: 3F6ECADA-70CD-4608-83A6-F42F5D0175E6 Dissolved Oxygen (daily average) > 6.0 mg/L TSS 30 mg/L 45 mg/L TRC 17 ug/1 Fecal coliform (geometric mean) 200/100 ml 400/100 ml Chronic Toxicity Pass/Fail (Quarterly test) 90% Engineering Alternatives Analysis (EAA). Please note that the Division cannot guarantee that an NPDES permit for a new or expanding discharge will be issued with these speculative limits. Final decisions can only be made after the Division receives and evaluates a formal permit application with all supporting data for the new/expanded discharge. In accordance with North Carolina Administrative Code 15A NCAC 2H.0105(c), the most environmentally sound alternative should be selected from all reasonably cost-effective options. Therefore, as a component of all NPDES permit applications for new or expanding flow, a detailed engineering alternatives analysis (EAA) must be prepared. The EAA must justify requested flows and provide an analysis of potential wastewater treatment alternatives. EAA guidance can be found at: https://files.nc.gov/ncdeq/Surface%20Water%20Protection/NPDES/permits/eaa-guidance- 20140501-dwr-swp-npdes_ 13.pdf. State Environmental Policy Act (SEPA) EA/EIS Requirements. A SEPA EA/EIS document may be required for projects that: 1) involve $10 Million or more of state funds; or 2) will significantly and permanently impact 10 or more acres of public lands. Please check with the DWR SEPA coordinator (David Wainwright, 919-707-9045) as to whether your project requires SEPA review. For projects that are subject to SEPA, the EAA requirements discussed above will need to be folded into the SEPA document. Additionally, if subject to SEPA, the NPDES Unit will not accept an NPDES permit application for a new/expanding discharge until the Division has approved the SEPA document and sent a Finding of No Significant Impact (FONSI) to the State Clearinghouse for review and comment. If you would like to discuss the contents of this letter or any other aspect of the project, please feel to reach out to David Hill at david.hill@ncdenr.gov or (919) 707-3612 at any time. At your request, David will coordinate a Teams meeting with all relevant players. All we will need from you is some proposed dates and times to set up a meeting. Respectfully, DocuSignedLL kow by: `1 • t'^.''U ` C464531431644FE... Michael Montebello Supervisor, NPDES Municipal Permitting Unit Electronic Copy: NCDWR Laserfiche NC WRC, Inland Fisheries, shannon.deaton@ncwildlife.org US Fish and Wildlife Service, Sarah_mcrae@fws.gov DWR/Water Quality Regional Office Page 3 of 4 DocuSign Envelope ID: 3F6ECADA-70CD-4608-83A6-F42F5D0175E6 DWR/Modeling, Pam Behm DWR/Basinwide Planning, Ian McMillan DWR/NPDES Server>Specs Page 4 of 4