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Home My WebLink AboutNC0020664_Pretreatment_HWA_Letter_20220628DocuSign Envelope ID: 39D5F951-7E43-4A3C-85EF-03B1C10A5CEC ROY COOPER Governor ELIZABETH S. BISER Secretary RICHARD E. ROGERS, JR. Director Town of Spindale Attn: Guy O'Connor, Superintendent P.O. Box 186 Spindale, NC 28160 Email: goconnor@spindalenc.net Dear Permittee: NORTH CAROLINA Environmental Quality 6/29/2022 Subject: HWA Approval Program: Town of Spindale NPDES Permit No NC0020664, 3.0 MGD Permit Class B Residuals No WQ0001953 Town of Spindale WWTP Rutherford County, ARO The Municipal Unit of the Division of Water Resources has reviewed the Headworks Analysis (HWA) for the Town of Spindale for its wastewater treatment plant (WWTP) working under the NPDES Permit No NC0020664 (effective on July 1, 2020). The HWA was initially received by the Division on November 13, 2020, followed by more information and revisions received on between February 9, 2022 and February 24, 2022. We regret the delay in providing this review. The Division concurs with the HWA calculations for all pollutants of concern, with the corrections and observations discussed below. The approved Maximum Allowable Headworks Loadings (MAHLs), Maximum Allowable Industrial Loadings (MAILs), and the basis for these values are found in the enclosed HWA and Allocation Table (AT) spreadsheet, which has the updates and corrections highlighted. Please ensure to replace or update the POTW's HWA AT spreadsheets with this approved one. 1. HWA Corrections a. POTW Average Flow: This was updated to 0.772 based on using all average monthly data from the DMRs for the time period. b. NPDES Limits: Copper was added as a pollutant of concern in the 2020 NPDES renewal, therefore the limit was added to the HWA. c. Water Quality Stream Standards: The POTW's NPDES Permit was renewed on June 10, 2020 and became effective July 1, 2020. The HWA was updated to include the use include the new NPDES limits including ammonia, copper, and silver. The HWA was also updated to use the site -specific water quality standards (WQS) from the Fact Sheet associated with this permit renewal (see the 2020 RPA tab in the attached spreadsheet). These WQS applied the new NC WQS adopted in 2016. These included new WQS for arsenic, cadmium, chromium, lead, nickel, and zinc. d. Removal Rates and Uncontrollable: Removal rates were updated to include all average monthly data from the DMRs for the time period. This update affected the removal rates for BOD, TSS, ammonia, chromium, copper, mercury, nickel, and zinc. The HWA was corrected to reflect these new values. The updated flow and DocuSign Envelope ID: 39D5F951-7E43-4A3C-85EF-03B1C10A5CEC removal rates information was also updated in the uncontrollable mass balance spreadsheet. This necessitated an update of the uncontrollable flow in the HWA spreadsheet to 0.6229 MGD (cell C9 in HWA) according to the Mass Balance sheet calculation. The uncontrollable mass balance spreadsheet had some incorrect formulas and was calculating values incorrectly. Please use the spreadsheet found on our website. e. Sludge: The sludge to disposal flow value was updated to 0.00265 based on the 2019 Annual Residuals Sampling Summary form from the Town's 2019 Annual Report (permit# WQ0001953). f. Silver: The HWA showed a calculated over allocation based on the dissolved metals stream standard. Recently DWR has decided to allow POTWs the option of using zero for data reported as below PQL (Practical Quantitation Limit) data when the PQL is sufficiently low (best available PQL). All recent WWTP influent and effluent silver data was below 1 ug/L PQL. Based on this data, the HWA was revised to use zero for the uncontrollable. If any future data shows a reported value above 1 ug/L PQL, contact the Pretreatment staff of the Municipal Unit within 30 days to discuss the need for future action. This change still resulted in a negative allocation for silver. The POTW should revise their IUPs silver limit to resolve this overallocation. Please submit this IUP modification to the Division by August 31, 2022. g. Copper: The HWA showed a calculated over allocation based on pass -through. The POTW should revise their IUPs copper limit to resolve this overallocation. Please submit this IUP modification to the Division by August 31, 2022. h. Allocation Table: The AT was updated to reflect the new SIU effective and expiration dates. 2. HWA Observations: Please feel free to contact the Pretreatment staff of the Municipal Unit if you have any questions or concerns about the changes outlined below. All corrected spreadsheets were emailed to you for your files, with the changes highlighted. Please ensure to replace or update POTW's HWA AT spreadsheets and supporting documents with these approved ones. a. Variable Practical Quantitation Levels (PQLs) in LTMP and HWA Data: It was noted that the PQL's fluctuate for many of the parameters from one sample to another. Going forward, the POTW must: i. ensure your lab is informed of your PQL requirements; ii. promptly review each set of lab results promptly to verify the correct PQL was obtained; iii. and where the specified PQL was not obtained, promptly contact the lab to require any necessary re -analysis by the lab to achieve the required PQL. 3. Required Updates a. LTMP updates Submit the updated Long -Term Monitoring Plan (LTMP) by September 30, 2022, addressing: i. The target PQL for the following parameter shall be updated in the LTMP: silver from 2.5 µg/L to 1 µg/L. ii. The Division recommends updating the PQL for the following parameters: arsenic (from 5.0 µg/L to 2.0 µg/L), cadmium (from 2.0 µg/L to 0.50 µg/L), copper (from 2.5 µg/L to 2.0 µg/L), and lead (from 5.0 µg/L to 2.0 µg/L). iii. Uncontrollable should be sampled quarterly not once per six months. DocuSign Envelope ID: 39D5F951-7E43-4A3C-85EF-03B1C10A5CEC 4. Next HWA Due date: The HWA approved today is based on DMR/LTMP data for the period of June 2017 through September 2020. Unless conditions at the POTW change significantly and thus warrant an earlier submittal (see Comprehensive Guide, Chapter 5, Section B), the POTW must submit an updated site -specific HWA by November 30, 2024 (after the reissue of the next NPDES permit renewal). Regardless of this approval action today, within 180 days of the effective date of any reissued/modified NPDES permit, the Permittee would be required to submit to the Division a written technical evaluation of the need to revise local limits (i.e., an updated HWA or documentation of why one is not needed) [NPDES Permit Section D, 4.]. This action may include revising, updating, or adding to the list of Significant Industrial Users (SIUs) and/or modifying SIU Industrial User Pretreatment Permit (IUP) limits. In addition, any executed Special Order of Consent (SOC) conditions or requirements related to pretreatment or pretreatment program updates must be complied with separately from this approval action. Federal and State pretreatment regulations require the local delegated pretreatment program to effectively control and document the discharge of wastewater from Significant/Categorical Industrial Users to the POTW. It is the POTW's responsibility to ensure that these objectives are consistently met. Thank you for your continued cooperation of the Pretreatment Program. If you have any questions or comments, please contact the Pretreatment Coordinator Keyes McGee [keyes. mcgee@ncdenr. gov] . Sincerely, DocuSigned by: IVUI (�t� lt d,L1 C464531431644FE... for Richard E. Rogers Jr., Director Division of Water Resources kl/Spindale.HWA.2022.Approval Attachments: Spindale.Approved HWA-AT (20664).2022 cc with attachments: DWR Asheville Regional Office — Pretreatment/ Mikal Willmer Municipal Unit File cc without attachments: Central Files (Laserfiche)