Document bB4Kd6GOx8p8jngbjvJ2Oxk83

United States Environmental Protection Agency Region 4 Enforcement and Compliance Assurance Division Water Enforcement Branch 61 Forsyth Street, SW Atlanta, Georgia 30303 Compliance Evaluation Inspection Report Project No. CV-TN0020885 -101222 Oliver Springs STP 435 Joel Road Oliver Springs, Tennessee, 37840 NPDES Permit Number: TN0020885 Date of Inspection: October 12, 2022 COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 Title and Approval Sheet Title: Compliance Evaluation Inspection Town of Oliver Springs, Oliver Springs STP Approving Official: Digitally signed by JAIRO JAIRO CASTILLO Date: 2022.12.09 15:59:40 CASTILLO _________________-0_5'_00_' ____________ Jairo Castillo, P.E., Chief Wastewater Enforcement Section Water Enforcement Branch Inspector: Digitally signed by DENNIS DENNIS SAYRE Date: 2022.12.12 06:38:52 SAYRE _________________-0_5'0_0_' ____________ Dennis Sayre, Environmental Engineer Wastewater Enforcement Section Water Enforcement Branch 1 Table of Contents 1. Introduction.................................................................................................................................... 1 2. Participants.................................................................................................................................... 1 3. Facility Description....................................................................................................................... 1 4. Inspections Procedures.................................................................................................................. 2 5. Findings & Conclusions................................................................................................................ 2 A. Permit Review......................................................................................................................... 2 B. Records and Reports ................................................................................................................. 2 C. Flow Measurement ................................................................................................................... 3 D. Sampling................................................................................................................................... 3 E. Site Visit (Operation and Maintenance) ................................................................................... 4 F. Effluent and Receiving Waters ................................................................................................. 5 6. Sludge Handling............................................................................................................................ 6 7. Discussion .................................................................................................................................... 6 Appendix A. List of effluent violations. ............................................................................................. I COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 1. Introduction On October 12, 2022, representatives of the United States Environmental Protection Agency, Region 4 and Tennessee Department of Environment and Conservation (TDEC) conducted a Compliance Evaluation Inspection (CEI) on the Oliver Springs Sewage Treatment Plant (STP), owned and operated by the Town of Oliver Springs (Town). The STP is located at 435 Joel Road Oliver Springs, Tennessee. The inspection was conducted under the authority of Section 308 of the Clean Water Act (CWA), as amended. This report provides a summary of the inspection. 2. Participants Name Dennis Sayre Sarah Snyder Robert Ramsey Thomas McCormick Travis Thrasher Position EPA Inspector TDEC Inspector Water Resources/Facilities Manager, Knoxville Field Office City Manager STP Lead Operator Number 404-562-9756 865-809-5086 865-203-3523 865-435-7722 865-426-9476 3. Facility Description The STP is an Oxidation Ditch type of activated sludge wastewater treatment system with an average design flow of 0.74 million gallons per day (MGD). The STP consists of an equalization (EQ) basin, head works with a vortex grit and solids removal device, a primary clarifier, one Oxidation Ditch with variable speed propeller mixers, two secondary clarifiers, a tertiary filtration system, chlorine contact chambers with two independent flow paths, a step aerator, and related appurtenances. Disinfection and dechlorination is achieved using chlorine gas and sodium bisulfate. Figure 1: Aerial Display of the STP 1 COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 4. Inspections Procedures The overall objective of this CEI was to evaluate the condition and operational performance of the STP and the Town's self-monitoring program and to offer compliance assistance as needed. Specific tasks included an opening conference, conducting interviews with STP staff, review of Discharge Monitoring Reports (DMRs) and other STP records, conducting a site visit throughout the STP, and a closing conference. 5. Findings & Conclusions The Town has been in Significant Non-Compliance (SNC) for 8 of the past 12 calendar quarters, primarily due to Ammonia (as Nitrogen) (NH3-N) and Total Residual Chlorine (TRC) exceedances. Of note, the Town has been in SNC for one of the past 4 quarters. The Town has also been in non-compliance with several other permit effluent limits as noted Appendix 1, which includes exceedances in E. coli, Total Nitrogen (TN), Total Phosphorus (TP), Total Suspended Solids (percent removal). The Town also reported several wet weather sanitary sewer overflows (SSOs). The Town was issued a TDEC Commissioner's Order (WPC14-002) in July 2014 for numerous effluent limit violations from the STP as well as SSOs from the collection system. The Order required the Town to develop and implement corrective action plans to eliminate SSOs and to rehabilitate the STP to prevent further violations of the National Pollutant Discharge Elimination System (NPDES) permit. The Order also directed the Town to develop and implement a Sewage Overflow Response Plan to ensure proper response to SSOs and to develop and implement various Capacity, Management, Operations, and Maintenance (CMOM) programs to facilitate proper asset management of the sewer system. The Order was concluded and terminated by TDEC on July 7, 2021. A. Permit Review The Town's NPDES permit has an effective date of August 1, 2018, and expires on June 30, 2023. The permit has report-only requirements for flow and concentrations of TN, and TP and sets forth limits on the allowable levels of Total Suspended Solids (TSS), Settleable Solids, carbonaceous biochemical oxygen demand (CBOD5), Total Phosphorus (loading only), NH3-N, Dissolved Oxygen (DO), E. coli, TRC, and pH. The permit also requires continuous monitoring of the STP influent and effluent flow rate. B. Records and Reports EPA's Integrated Compliance Information System (ICIS) database shows the facility to be in SNC due to permit limit exceedances, as discussed above. Appendix 1 is a list of effluent exceedances from October 2019 through October 2022. ICIS data can be reviewed on the EPA's Enforcement and Compliance History Online (ECHO)1 public website. 1 https://echo.epa.gov 2 COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 C. Flow Measurement A Parshall flume and ultrasonic flow meter is used to measure influent flow rate. Effluent flow rate is measured using ultrasonic metering device that measures the depth of effluent in the chlorine contact chamber (CCC). The CCC is divided into two independent flow paths of which is selected by the operator and can be operated simultaneously or independently. The effluent ultrasonic transducer is mounted on a galvanized pipe and is manually pivoted to read one CCC depth at a time, (Figure 2). Flow readings are doubled when both paths are being utilized. Figure 2. Effluent ultrasonic transducer. Red arrows represent separate Flow paths in the CCC. D. Sampling Composite effluent samples are collected at the bottom of the step aeration basin. Two buffered thermometers were located in the refrigeration bin of the composite sampler unit. The composite sampler appeared to be in good condition. The STP operators analyze samples for all pollutants indicated in the NPDES permit with exception of TN and TP. Waypoint Analytical conducts sample analysis for TN and TP. The EPA reviewed laboratory bench sheets for the month of July 2022 and reviewed the sampling Chain of Custody (COC) sheet for samples collected in December 2021 and July 2022 and subsequent lab reports. No deficiencies were noted. 3 COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 E. Site Visit (Operation and Maintenance) The STP utilizes an EQ basin to capture excess wet weather flow. The EQ basin was constructed as part of capital improvements associated with the 2014 Commissioner's Order and appeared to be in good operating condition. The Headworks consists of a vortex grit removal unit, and a Parshall flume with an ultrasonic meter (Figure 3). Figure3. Headworks grit removal unit and influent Parshall flume. The influent appeared to be very thin (void of solids), indicating excessive rain derived infiltration and inflow (RDII) in the sewage collection system. The mixed liquor suspended solids (MLSS) in the Oxidation Ditch was dark brown and experiencing thick brown foaming that covered approximately 15 to 20% of the surface (Figure 4). Variable drive propeller mixers were installed in 2016 and are used to circulate and aerate the MLSS. Figure 4. Oxidation Ditch MLSS. 4 COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 One of the clarifiers was experiencing excessive foaming (Figure 5). Figure 5. Excessive foaming in Clarifier. Nutrient removal is achieved by alternating aerobic and anaerobic zones around the oxidation ditch. Continuous DO meters are installed to assist in the process. New DO meters were installed in September/October 2021. The operator stated that the Return Activated Sludge/Waste Activated Sludge (RAS/WAS) valve is a turn valve ( turn valves fully opens or closes the valve with a 90-degree turn). The type of valve installed does not allow for fine tuning adjustments of RAS which can limit the STP operator's ability to maintain proper concentrations of biomass in the oxidation ditch. F. Effluent and Receiving Waters The STP discharges into Poplar Creek. The outfall at the creek was not readily accessible. The effluent was clear, Figure 6. 5 COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 Figure 6. Left, effluent discharged from CCC. Right, step aeration. 6. Sludge Handling Sludge is thickened in a sludge digester basin and dewatered using a screw press before hauling to the local landfill. 7. Discussion Documents provided by TDEC show that the Town has invested at least $7M on collection system rehabilitation, mostly pipe lining, and another $7M on STP rehabilitation in efforts to comply with the Commissioner's Order. The Town's NPDES compliance history has improved significantly since the first calendar quarter following termination of the Commissioner's Order. Table 1 below is a summary of violations taken from Appendix A following termination of the Order. STP rehabilitation appears to have substantially corrected chronic NH3-N and e. coli exceedances, among other effluent violations of the past. The appearance of the influent suggests that RDII in the collection system is still a significant problem. The use of the EQ basin greatly assists with stabilizing sewage diluted with RDII to the STP, but prolonged RDII diluted influent will eventually impact the performance of the STP. Prolonged RDII diluted influent prompts the operator to maintain older MLSS in the oxidation ditch to make up for the loss of food for the microorganisms, which in turn contributes to thick brown foaming at the surface of the oxidation ditch and in the clarifiers and can also lead to effluent violations of ammonia and suspended solids removal efficiency (such as the violations noted in Table 1 below). Also, treating excessive RDII at the STP increases treatment costs and increases wear and tear on the STP equipment. The EPA strongly recommends that the Town continue to improve the collection system to remove excess RDII. The EPA also recommends the Town conduct a flow study throughout the sewage collection system, if not already completed or planned, to ascertain where the RDII is coming from following the rehabilitation efforts. Special attention should be given in assessing manhole crowns and sewage laterals. 6 COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 Measuring effluent flow from an ultrasonic transducer that is not stationary does not provide for a reliable flow reading. The pivot point on the mounting pole will loosen over time and cause the transceiver to tilt and draw closer to the effluent which will impact its accuracy. The EPA recommends adding an additional flow meter to maintain continuous monitoring for both CCC flow paths and replacing the pivoting transducer mount with a permanent/solid mount. The EPA also recommends replacing the turn RAS/WAS control valve with a multi-turn valve as explained in Section 5.E above. End of Reporting Month Wet Weather SSO Phosphorus (lb/yr) Ammonia (Daily Max mg/L) Ammonia (Wk Ave mg/L) Ammonia (Mo Ave mg/L) SS % Removal CBOD5 (Weekly Ave lb/day) 7/31/2021 X X X X X 8/31/2021 X X X X 9/30/2021 X X X X 12/31/2021 X X 1/31/2022 2/28/2022 X 2/28/2022 3/31/2022 X X 2/28/2022 7/31/2022 X X 9/30/2022 X X Table 1. Summary of violations reported from July 1, 2021, through October 31, 2022. END OF REPORT 7 COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 Appendix A. List of effluent violations. Monitoring Period End Date Parameter Description 10/31/2020 NH3-N 12/31/2020 NH3-N 1/31/2021 NH3-N 1/31/2021 NH3-N 7/31/2021 NH3-N 7/31/2021 NH3-N 8/31/2021 NH3-N 1/31/2022 NH3-N 2/28/2022 NH3-N 8/31/2019 Chlorine, total residual Chlorine, total 10/31/2019 residual Chlorine, total 11/30/2019 residual Chlorine, total 12/31/2019 residual 1/31/2020 Chlorine, total residual Permit Limit Value 9.3 43 43 7 9.3 1.5 9.3 43 43 0.08 0.08 0.08 0.08 0.08 DMR Reported Value 20.877 66.079 69.423 9.865 14.185 3.288 13.118 67.025 64.155 0.38 0.16 0.67 2.24 0.85 I Units lb/d lb/d lb/d mg/L lb/d mg/L lb/d lb/d lb/d mg/L mg/L mg/L mg/L mg/L Monitoring Frequency MO AVG MO AVG MO AVG MO AVG MO AVG MO AVG MO AVG MO AVG MO AVG DAILY MX DAILY MX DAILY MX DAILY MX DAILY MX % Exceeded 124 54 61 41 53 119 41 56 49 375 100 738 2700 963 Violation Severity Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 Monitoring Period End Date Parameter Description 4/30/2020 Chlorine, total residual 7/31/2020 Chlorine, total residual 1/31/2021 Chlorine, total residual 2/28/2021 Chlorine, total residual 10/31/2020 NH3-N 12/31/2020 NH3-N 3/31/2022 NH3-N 3/31/2022 NH3-N 2/29/2020 Nitrogen, total [as N] 3/31/2020 Nitrogen, total [as N] 4/30/2020 Nitrogen, total [as N] 5/31/2020 Nitrogen, total [as N] 6/30/2020 Nitrogen, total [as N] 7/31/2020 Nitrogen, total [as N] 8/31/2020 Nitrogen, total [as N] 9/30/2020 Nitrogen, total [as N] 10/31/2020 Nitrogen, total [as N] 11/30/2020 Nitrogen, total [as N] 12/31/2020 Nitrogen, total [as N] Permit Limit Value 0.08 0.08 0.08 0.08 1.5 7 43 7 30782.8 30782.8 30782.8 30782.8 30782.8 30782.8 30782.8 30782.8 30782.8 30782.8 30782.8 DMR Reported Value 0.95 0.31 0.29 0.47 1.588 8.646 58.751 8.101 45538.4 45156.8 41547.7 42744.9 40476.1 39781.5 39140.9 38658.8 38628.5 38121.9 38048.5 Units mg/L mg/L mg/L mg/L mg/L mg/L lb/d mg/L lb/yr lb/yr lb/yr lb/yr lb/yr lb/yr lb/yr lb/yr lb/yr lb/yr lb/yr Monitoring Frequency DAILY MX DAILY MX DAILY MX DAILY MX MO AVG MO AVG MO AVG MO AVG ANNL TOT ANNL TOT ANNL TOT ANNL TOT ANNL TOT ANNL TOT ANNL TOT ANNL TOT ANNL TOT ANNL TOT ANNL TOT % Exceeded 1088 288 263 488 6 24 37 16 48 47 35 39 31 29 27 26 25 24 24 Violation Severity Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Significant Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation II COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 Monitoring Period End Date Parameter Description 10/31/2020 NH3-N 10/31/2020 NH3-N 12/31/2020 NH3-N 1/31/2021 NH3-N 1/31/2021 NH3-N 3/31/2021 NH3-N 5/31/2021 NH3-N 6/30/2021 NH3-N 7/31/2021 NH3-N 7/31/2021 NH3-N 8/31/2021 NH3-N 8/31/2021 NH3-N 8/31/2021 NH3-N 9/30/2021 NH3-N 9/30/2021 NH3-N 9/30/2021 NH3-N 12/31/2021 NH3-N 1/31/2022 NH3-N 2/28/2022 NH3-N Permit Limit Value 3 14.2 62 62 15 62 3 3 2.3 3 3 2.3 14.2 14.2 3 2.3 62 62 62 DMR Reported Value 6.94 20.876 71.688 69.422 18.5 63.677 3.13 3.23 3.0686 16.2 5.71 3.66 39.71 21.455 8.27 4.196 69.506 100.536 141.9 Units mg/L lb/d lb/d lb/d mg/L lb/d mg/L mg/L mg/L mg/L mg/L mg/L lb/d lb/d mg/L mg/L lb/d lb/d lb/d Monitoring Frequency DAILY MX WKLY AVG WKLY AVG WKLY AVG DAILY MX WKLY AVG DAILY MX DAILY MX WKLY AVG DAILY MX DAILY MX WKLY AVG WKLY AVG WKLY AVG DAILY MX WKLY AVG WKLY AVG WKLY AVG WKLY AVG % Exceeded 131 47 16 12 23 3 4 8 33 440 90 59 180 51 176 82 12 62 129 Violation Severity Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation III COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 Monitoring Period End Date Parameter Description 3/31/2022 NH3-N 3/31/2022 2/29/2020 3/31/2020 4/30/2020 5/31/2020 6/30/2020 7/31/2020 8/31/2020 9/30/2020 10/31/2020 11/30/2020 12/31/2020 1/31/2021 4/30/2021 5/31/2021 6/30/2021 7/31/2021 8/31/2021 9/30/2021 12/31/2021 NH3-N Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] Phosphorus, total [as P] 10/31/2019 E. coli Permit Limit Value 62 10 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 4830.2 941 DMR Reported Value Units 73.039 lb/d 10.73 mg/L 6302 lb/yr 5827.9 lb/yr 6298.9 lb/yr 6566 lb/yr 6007.9 lb/yr 5771.4 lb/yr 5793.2 lb/yr 5854.4 lb/yr 6176 lb/yr 6002.4 lb/yr 6131.8 lb/yr 5762.8 lb/yr 5233.8 lb/yr 53984 lb/yr 5010 lb/yr 5044.9 lb/yr 5074.2 lb/yr 4859.5 lb/yr 5146.1 lb/yr 2419.6 #/100mL IV Monitoring Frequency WKLY AVG WKLY AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG ROLL AVG DAILY MX % Exceeded 18 7 30 21 30 36 24 19 20 21 28 24 27 19 8 1018 4 4 5 1 7 157 Violation Severity Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation COMPLIANCE EVALUATION INSPECTION REPORT Oliver Springs STP- CV-TN0020885-101222 Monitoring Period End Date Parameter Description 11/30/2019 E. coli 11/30/2020 E. coli 12/31/2021 BOD5 2/28/2022 BOD5 4/30/2021 10/31/2019 11/30/2019 12/31/2019 9/30/2021 CBOD, % removal Solids, suspended % removal Solids, suspended % removal Solids, suspended % removal Solids, suspended % removal 12/31/2019 SSO, Dry Weather 7/31/2019 SSO, Wet Weather 10/31/2019 SSO, Wet Weather 12/31/2019 SSO, Wet Weather 3/31/2021 SSO, Wet Weather 5/31/2021 SSO, Wet Weather 7/31/2021 SSO, Wet Weather 8/31/2021 SSO, Wet Weather 9/30/2021 SSO, Wet Weather 2/28/2022 SSO, Wet Weather 7/31/2022 SSO, Wet Weather 9/30/2022 SSO, Wet Weather Permit Limit Value 941 941 154 154 40 40 40 40 40 0 0 0 0 0 0 0 0 0 0 0 0 DMR Reported Value 1119.9 1011.2 183.4 182 21.1 -40 -33.3 -30.4 20 3 3 2 3 3 3 3 3 3 2 1 1 Units #/100mL #/100mL lb/d lb/d % % % % % occur/mo occur/mo occur/mo occur/mo occur/mo occur/mo occur/mo occur/mo occur/mo occur/mo occur/mo occur/mo Monitoring Frequency DAILY MX DAILY MX WKLY AVG WKLY AVG DAILY MN DAILY MN DAILY MN DAILY MN DAILY MN MO TOTAL MO TOTAL MO TOTAL MO TOTAL MO TOTAL MO TOTAL MO TOTAL MO TOTAL MO TOTAL MO TOTAL MO TOTAL MO TOTAL % Exceeded 19 7 19 18 32 133 122 117 33 Violation Severity Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation Noncompliance Effluent Violation V