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Home My WebLink AboutNC0081621_Draft Permit_20180821 (2) ROY COOPER Governor N MICHAEL S.REGAN Sem Maly LINDA CULPEPPER Water Resources Interim Duector ENVIRONMENTAL QUALITY August 21, 2018 Mr. Timothy R. Kiser, P.E. Engineering Director Water and Sewer Authority of Cabarrus County 232 Davidson Highway Concord,NC 28027 Subject: Draft NPDES Permit Permit NC0081621 Muddy Creek WWTP Cabarrus County Grade II(0.15 & 0.3 MGD) & III (0.53 MGD) Biological WPCS SIC Code 4952 Dear Mr. Kiser: Enclosed with this letter is a copy of the Draft NPDES permit renewal and modification for your facility. Please review this draft carefully to ensure thorough understanding of the requirements and conditions it contains. There are several changes from the existing permit, including the following: • The Division reviewed and concurred with your flow justification of 0.53 MGD, as well as the EAA conclusion that the direct discharge to surface water alternative is the most environmentally sound alternative selected from all reasonably cost-effective options (per 15A NCAC 2H.0105(c)(2)). • The Supplement to Permit Cover Sheet has been updated to include prior to expansion to 0.53 MGD with outfall 002,plans and specifications must be submitted to the Division for approval and subsequent issuance of Authorization to Construct(A to C). No construction may begin until such authorization has been issued by the Division.Also,no discharge via outfall 002 may begin until submission of Engineer's Certification of completion to the Division. • Special condition has been added to the permit (See A. (5.)) requiring closure of the existing facility (outfall 001) once the construction of the new facility (outfall 002) has been completed and the Engineer's Certification of completion has been submitted to the Division. • The Effluent Limitations and Monitoring Requirements (A. (3.)) for the new facility with outfall 002 has been added to the permit. • The topographic map was updated to include the proposed location of outfall 002 and the location of the existing facility. State of North Carolina I Environmental Quality I Water Resources 1617 Mail Service Center Raleigh,North Carolina 27699-1617 919 807 6300 Page 12 • Upstream and effluent total hardness quarterly monitoring have been added to the permit for all flow tiers (0.15 and 0.3 MGD) as required by the implementation guidance for the new dissolved metal standards [ See A. (1.) and A. (2.)]. • The Permittee reported Total Silver at less than detection,with detection levels<2.5 µg/L. The Permittee's permit discharge requirement for Total Silver is 10.05 µg/L for flow tier of 0.15 MGD and 5.05 µg/L for flow tier of 0.3 MGD. DWR's laboratory identifies the Practical Quantification Limit(PQL) for Total Silver as 1 µg/L. In this case,the Permittee should test for Total Silver down to the recommended PQL and as long as the Permittee reports effluent Total Silver less than the PQL or a lower reporting level of the procedure, the Permittee will be considered in compliance with its permit discharge requirement (limit). As stated above, in accordance with 15A NCAC 2B .0500 the Permittee shall test for Total Silver down to the lower reporting level of the procedure. The Division can modify this permit and add a limit or limits during the next renewal if this regulation is not satisfied. • Since the facility has a pretreatment program, Whole Effluent Toxicity (WET) limits of 0.6% and 1.2% have been added to flow tiers of 0.15 and 0.3 MGD, respectively (See A. (1.) and A. (2.)). In addition, special condition A. (4.) Chronic Toxicity Permit Limit (Quarterly) has been added to the permit in accordance with 15 A NCAC 02B.0200 and 15A NCAC 2B.0500. Please review each paragraph carefully. Permittees should be aware that the objective of whole effluent toxicity limits placed in NPDES permits is to prevent discharge of toxic substances in amounts likely to cause chronic or acute toxicity to wildlife in the receiving stream and represents the only feasible method of evaluating the combined effects of constituents of complex wastestreams. Following is a link to review DWR's WET Strategy: https://files.nc.gov/ncdeq/Water%20Quality/ATU%20Documents/Whole%20E ffluent%20Toxicity%20(WET)/WET%20Monitoring%20and%20Reporting/NCDWQ%2 OWET%20Strategy.pdf Since,WET testing is a vital component to implementing water quality standards under the NPDES permits program in accordance with the CWA Section 402, all the state environmental agencies with NPDES programs implement WET testing. • Effluent pollutant scans requirements have been added to Effluent Limitations and Monitoring Requirements [See A. (1.) and A. (2.)]. Special condition A. (6.) to include specific three years in which the effluent Pollutant Scan shall be performed (2020, 2021, 2022) and submitted with your next renewal application per Federal Regulations [40 CFR 122.21(j)(4)] has been added to the permit. In addition,at the end of the Special Condition, 2nd species Toxicity Testing Requirements for municipal permit renewals per Federal Regulations [40 CFR 122.21(j)(5)] have been added. Please review each paragraph carefully. • Federal regulations require electronic submittal of all discharge monitoring reports (DMRs) and program reports. The requirement to continue reporting discharge monitoring data electronically using the NC DWR's Electronic Discharge Monitoring Report(eDMR) internet application has been added to your NPDES permit[See Special Condition A. (7.)]. • Parameter codes have been added to the Effluent Limitations and Monitoring Requirements [ See A. (1.) and A. (2.)].