Document 3JdEDbmxG2gXq8N211ddzmgXO

WASTEWATER TREATMENT SYSTEM COMPLIANCE EVALUATION INSPECTION REPORT Purpose: NPDES Compliance Evaluation Inspection Facility: City of Vermilion WPCF 799 West River Road Vermilion, Ohio 44089 NPDES Permit Number: OH-0023612 Dates of Inspection: July 14-15, 2021 U.S. EPA Inspector: Dean Maraldo, EPA Region 5; (312) 353-2098; maraldo.dean@epa.gov U.S. EPA Chemist: Ken Gunter, EPA Region 5; (312) 353-9076; gunter.kenneth@epa.gov City of Vermilion WPCF Representatives: Robert Yost, Superintendent and operator (class 3); (440) 204-2455; robertyost@vermilion.net Garrett Fannin, operator (class 2) Eric Mayer, operator (class 2) Branden Clark, facility maintenance John Majer, laboratory technician and operator (class 3) Report Prepared by: Dean Maraldo, EPA Region 5 Inspector Maraldo, Digitally signed by Maraldo, Dean EPA Inspector Signature: _D_e__a_n_________D06a_:t3e_5::25_012_-10_.50'_70.02_'2____________ Approver Name & Title: Ryan Bahr, Chief, Section 2, Water Enforcement and Compliance Assurance Branch Digitally signed by RYAN RYAN BAHR BAHR Date: 2021.07.22 Approver Signature/Date ______________08_:1_5:_17_-0_5_'00_' ______________ City of Vermilion WPCF CEI Inspection Report [This page intentionally left blank] City of Vermilion WPCF CEI Inspection Report TABLE OF CONTENTS I. Introduction...................................................................................................................... 1 II. Background ...................................................................................................................... 1 III. Inspection Activity Summary .......................................................................................... 3 IV. Closing Conference, Areas of Concern, and Other Observations ................................... 8 V. Documents Received and References ............................................................................ 11 LIST OF ATTACHMENTS Attachment A: Diagram of the Facility wastewater treatment system Attachment B: Documents received during the inspection Attachment C: Photo Log Attachment D: 2017 Method Update Rule Attachment E: July 14, 2021 Inspection Location Map City of Vermilion WPCF CEI Inspection Report [This page intentionally left blank] City of Vermilion WPCF CEI Inspection Report I. INTRODUCTION On July 14-15, 2021, I inspected the City of Vermilion WPCF ("Facility"). I assessed the Facility's compliance with its National Pollutant Discharge Elimination System ("NPDES") permit and the Clean Water Act. The inspection consisted of the following major activities: Inspection opening conference; Interview/discussions with representatives from the Facility including a description of facility operations and maintenance ("O&M"), results of Discharge Monitoring Report (DMR) review, causes of effluent limit exceedances, the status of NPDES permit-specific reports, self-monitoring and laboratory activities, and sanitary sewer overflows ("SSOs"); Physical inspection of the Facility, including the in-house laboratory; Physical inspection of select SSO locations; and Closing conference. This report summarizes the results of the inspection. The following organizations and representatives were involved in the inspection of the Facility: City of Vermilion WPCF: Robert Yost, superintendent and operator (class 3) Garrett Fannin, operator (class 2) Eric Mayer, operator (class 2) Branden Clark, facility maintenance John Majer, laboratory technician and operator (class 3) U.S. EPA: Dean Maraldo, inspector Ken Gunter, chemist II. BACKGROUND The Facility is authorized to discharge under NPDES permit OH-0023612 ("permit"). The City of Vermilion ("City") is responsible for the Facility's operation and compliance with NPDES permit requirements. The City is responsible for conducting monitoring activities and reporting monitoring results to the Ohio Environmental Protection Agency ("Ohio EPA"). Currently, the City employs two Ohio Class 3 certified operators for the Facility, including the Facility Superintendent, Robert Yost, and John Majer, who serves as a laboratory technician. In addition, two Ohio Class 2 certified operators, Garrett Fannin and Eric Mayer, are responsible for maintenance of the Facility and associated lift stations, along with maintenance technicians Branden Clark and Michael Lazuski. Sewer collection system maintenance is managed by the City's Water Department. According to the NPDES Permit Fact Sheet (Ohio EPA, 2016), the Facility was built in 1967 with a design flow of 2.5 million gallons per day ("MGD") and a peak flow of 6.5 MGD. 1 City of Vermilion WPCF CEI Inspection Report Vermilion WPCF has the following treatment processes (see Attachment A for a diagram of the Facility wastewater treatment system): Mechanical Bar Screen Bucket Grit Removal Primary Clarification Activated Sludge (extended aeration/fine bubble) Phosphorus Removal (ferrous chloride) Final Clarifiers Chlorination (sodium hypochlorite) Dechlorination (sodium bisulfite) The Facility was subject to an Ohio EPA Director's Final Findings and Orders ("DFF&O") to eliminate pump station overflows. The DFF&O was signed on May 25, 2011, ordering the elimination of overflows at Elberta Beach pump station and Romps pump station. According to the NPDES Permit Fact Sheet (Ohio EPA, 2016), as of May 2016, Vermilion WPCF eliminated SSOs at both pump stations, thereby fulfilling the requirements in the DFF&O. The Facility reported, via electronic discharge monitoring reports ("DMRs") submitted to Ohio EPA, 50 permit effluent limit exceedances from June 2016 to May 2021, and 64 SSOs from February 2017 to May 2021. Prior to the inspection and per my request, the Facility Superintendent provided, via email, the Facility DMRs and associated laboratory bench sheets from July 2020 to May 2021. I reviewed the information and confirmed the effluent limit exceedances and SSOs summarized below: Effluent Limit Exceedances Summary OH0023612: CITY OF VERMILION WPCF, VERMILION, OH 44089-1324 Monitoring Period Date Range: 07/01/2020 to 05/31/2021 Monitoring Period Date 7/31/2020 7/31/2020 7/31/2020 7/31/2020 7/31/2020 7/31/2020 7/31/2020 7/31/2020 10/31/2020 10/31/2020 10/31/2020 10/31/2020 10/31/2020 11/30/2020 2/28/2021 2/28/2021 2/28/2021 2/28/2021 2/28/2021 Parameter Description Solids, total suspended Solids, total suspended Solids, total suspended Solids, total suspended N, ammonia total (as N) N, ammonia total (as N) N, ammonia total (as N) Chlorine, total residual Solids, total suspended Solids, total suspended Solids, total suspended N, ammonia total (as N) E. coli, MTEC-MF Mercury, total low level Solids, total suspended Solids, total suspended Solids, total suspended Solids, total suspended Phosphorus, total (as P) Limit Type MO AVG WKLY MAX MO AVG WKLY MAX MO AVG WKLY MAX WKLY MAX DAILY MX WKLY MAX WKLY MAX MO AVG WKLY MAX WK GEOMN MO AVG WKLY MAX WKLY MAX MO AVG MO AVG WKLY MAX DMR Value 69.98 1611 414.7 267.2 5.9 15 92 0.19 1500 76.9 382 98 490.571 2.71E-06 2360 159 44 608 25.4 DMR Value Unit mg/L kg/d kg/d mg/L mg/L mg/L kg/d mg/L kg/d mg/L kg/d kg/d MPN/100mL mg/L kg/d mg/L mg/L kg/d kg/d Limit Value 30 426 284 45 5.8 8.7 82 0.02 426 45 284 82 284 2.6E-06 426 45 30 284 14.2 Limit Value Qualifier <= <= <= <= <= <= <= <= <= <= <= <= <= <= <= <= <= <= <= 2 City of Vermilion WPCF CEI Inspection Report Reported SSOs July 2020-May 2021 Station 300 300 300 302 302 302 302 302 300 Parameter Overflow Occurrence Overflow Occurrence Overflow Occurrence Overflow Occurrence Overflow Occurrence Overflow Occurrence Overflow Occurrence Overflow Occurrence Overflow Occurrence Date 5/11/2021 3/1/2021 12/5/2020 11/24/2020 10/22/2020 10/21/2020 9/7/2020 8/31/2020 8/28/2020 Reported Value 1 1 1 1 1 1 1 1 1 I also compared bench sheets from July 2020 to May 2021 against reported values in the DMRs and found no issues or errors. III. INSPECTION ACTIVITY SUMMARY III. A. Opening Conference I arrived at the Facility with U.S. EPA Chemist Ken Gunter on July 14, 2021 at 8:30 a.m. We met Robert Yost, Facility Superintendent, in his office and began the opening conference with introductions. I presented my U.S. EPA Inspector credentials to Mr. Yost and then discussed the intended scope of the inspection. I thanked Mr. Yost for providing the Facility DMRs and associated bench sheets prior to the inspection. We then began the Interview portion of the inspection. III. B. Interview I started the interview portion of the inspection by asking Mr. Yost if the City submitted an NPDES permit reapplication package, as the Facility's NPDES permit expires on November 30, 2021. He confirmed that the permit reapplication package was submitted to Ohio EPA. I asked Mr. Yost to describe current staffing for wastewater operations. He said the Facility staff includes two maintenance technicians, two operators, and a laboratory technician. I then asked Mr. Yost to provide some general information about the sewer system, including the length of sewer conveyance, number of lift station, and number of service connections. He explained that management of the sewer collection system was managed by the Water Department so he would have to get back to me with details. Mr. Yost did confirm that the system includes 11 lift stations. [On July 21, 2021, Mr, Yost confirmed, via email, that there were 4,588 sanitary sewer connections, including commercial, residential, and multi-units in the system]. At this point in the interview the Facility's two class 2 operators, Garrett Fannin and Eric Mayer, joined the discussion. Mr. Fannin added that all of the lift stations are alarmed and all but three have remote telemetry. Mr. Yost and Mr. Fannin also mentioned the City is investing in a new SCADA-type technology from Mission Communications and plans to have the system in place by the end of the year. Following up on the earlier discussion about the collection system, Mr. Fannin estimated, based on the number of water service connections, about 5,500 sewer service connection in the system, serving about 10,000 residents. Mr. Mayer added that there were some septic areas in the City so the estimate of sewer service connections may be a bit lower. I asked 3 City of Vermilion WPCF CEI Inspection Report about current SSO points in the collection system. Mr. Yost and Mr. Fannin confirmed there are three re-occuring SSO points in the collection system, including Elberta Lift Station, River Lift Station, and Vermilion-on-the-Lake ("VOL") Lift Station. Reserving the discussion about SSOs for later in the inspection, I asked Mr. Yost how things were going at the wastewater treatment plant. He summarized by saying that "lots of things need to be replaced" and added that they have replaced or upgraded system components recently, including a new bar screen. I asked about specific effluent limit exceedances and potential causes, starting with July 2020 exceedances of total suspended solids ("TSS") and nitrogenammonia total (as N). Mr. Yost explained that two of the six clarifiers were down since he started at the Facility in 2018. Operator Branden Clark joined the discussion and added that the two clarifiers were placed back on line in October 2020. I asked about the cause of effluent limit exceedances in October 2020, including TSS, nitrogen-ammonia total (as N), and E. coli; and TSS exceedances in February 2021. Mr. Yost attributed the exceedances to air lift issues and insufficient air to support aeration. He added that a third blower was recently installed to help address the issue. Last, I asked about the phosphorus effluent limit exceedance in February 2021. Mr. Yost said the exceedance was caused by a ferrous chloride system pump failure. I asked Mr. Yost to talk about operation and maintenance ("O&M") practices at the Facility. Mr. Yost explained that Facility had O&M plans but was not sure if the Water Department had a written O&M plan for the collection system. Routine O&M practices include visiting key lift stations every day and recording maintenance activities in a written log (see Attachment B for example of daily O&M log entries). I asked Mr. Yost to describe how the Facility is operating. He said infiltration and inflow ("I&I") is the biggest issue leading to compliance issues, with average daily flows of approximately 1 MGD and peak daily flows of up to 6.5 MGD. He also described recent issues with key wastewater treatment system components. As discussed above, for most of the past year the Facility operated without the use of all six clarifiers and insufficient air support aeration, and is currently operating without clarifier #6 and the grit removal unit. After the O&M discussion, I asked about SSO and basement backup complaints. Mr. Yost said he wasn't aware of many backup complaints. He added that the Water Department would receive complaints and said he would check to see if they recorded backups and complaints and let me know if any records existed. Mr. Yost said he was aware of one resident concerned about SSOs. I went over the status of various non-DMR reports required under the permit. Mr. Yost provided a copy of the Ammonia-Nitrogen Reduction Evaluation (Attachment B) which was dated December 2, 2020, but due to Ohio EPA, pursuant to the Permit Part I.C.3.e., by December 1, 2019. Mr. Yost also provided the Annual Mercury PMP report required pursuant to the permit (Attachment B). The report was submitted by the March 1, 2021 deadline. However, the copy of the report provided was missing required information such as a list of potential mercury sources (Permit Part II.U.1.g.ii) and a summary of efforts to reduce mercury (Permit Part II.U.1.g.iii). Pursuant to Permit Part I.C.5.e.ii., the Facility was required to submit a No Feasible Alternatives Analysis and Schedule ("NFA") regarding the reduction of I&I by December 1, 2019. Mr. Yost provided documentation including letters sent to Ohio EPA and a related Notice of Violation and 4 City of Vermilion WPCF CEI Inspection Report correspondence from Ohio EPA (Attachment B) discussing the Facility's failure to comply with Permit Part I.C.5.e.ii., and eventual resolution of the violation via a permit modification request. I asked to see the written notification procedures between the Facility and the downstream public water supply system, required pursuant to Permit Part II.AA.3. He was not aware of the requirement and said he would look into it and get back to me. [On July 21, 2021, Mr. Yost provided a written notification procedure via email. However, the procedure was not dated and did not cover upsets, spills, and bypasses. He later confirmed that the procedure was recently developed]. Last, I asked Mr. Yost about the status of the Facility's storm water pollution prevention plan ("SWPPP") required pursuant to Permit Part V. He was not able to produce the SWPPP and said he would look for it and get back to me. [On July 21, 2021, Mr. Yost provided an update on the SWPPP status, explaining that it is currently being developed by a contract engineering firm]. III. C. Physical Facility Inspection The physical inspection of the Facility began at 10:10 a.m. on July 14, 2021. The physical inspection is summarized below. Photographs referenced below are included in the Photo Log (Attachment C). A diagram of the wastewater treatment system is provided in Attachment A. Facility laboratory technician John Majer joined us for the inspection of the on-site laboratory. I started by mentioning that I planned to take photographs during the inspection and asked if there were any concerns regarding potential confidential business information ("CBI"). Mr. Yost stated that there were no concerns regarding potential CBI. Laboratory: Based on our review of laboratory bench sheets, Mr. Gunter recommended adding the dates and times for both sample collection and analysis on laboratory bench sheets to allow for confirmation of holding times. Mr. Gunter also requested a copy of a recent chain-of-custody form for samples sent to the contract laboratory for analysis. Mr. Yost provided a copy of a recent chain-of-custody form (Attachment B). Mr. Gunter noted that there was a gap in time on the form from when a sample was collected (6/22/2021) to when it was turned over to the contract laboratory (7/1/2021). Mr. Gunter pointed out that the chain-of-custody form should allow reviewers to track custody of a sample from the time of collection to the time the sample is delivered to the laboratory. I asked Mr. Majer and Mr. Yost if they conduct any process monitoring. Mr. Majer stated that they conduct settling tests two or three times per day and routinely monitor for dissolved oxygen in the aeration tanks. On our walk through of the laboratory we were able to see adequate bench, instrumentation, storage, and recordkeeping space. The laboratory was a clean and orderly work area. We found the laboratory to have adequate space for personnel to circulate and at least two options for entry and egress. The laboratory appeared to have adequate humidity and temperature control, adequate lighting and ventilation, and a fume hood system. We noted that the laboratory appears to have the necessary equipment such as hot plate, incubator, water bath, refrigerator for samples, glassware, pH meter, thermometer, and balance. The laboratory had emergency equipment such as a fire extinguisher, eye wash station, shower, first aid kit, lab coats, gloves, and goggles. 5 City of Vermilion WPCF CEI Inspection Report Mr. Majer described how he maintains records of each set of analyses performed, including the order in which calibration, QA/QC, and samples were analyzed (i.e., analysis run logs or instrument run logs) and instrument calibration (see Photograph VWPC0001.jpg). Mr. Majer said he follows written requirements (e.g., standard operating procedures or "SOPs") for daily operation of instruments and equipment, and the SOPs were available in the laboratory at the time of inspection (see updated SOPs in Photograph VWPC0002.jpg and bench sheets in VWPC0003.jpg). Mr. Majer appears to appropriately use standards and blanks to perform standard calibration procedures, and uses standard concentrations that closely bracket actual sample concentrations. Sources of standards are documented and where possible, traceable to a national standard (e.g., National Institute of Standards and Technology (see Photograph VWPC0004.jpg - buffer solutions documenting opening and expiration dates). Mr. Gunter pointed out that the laboratory should ensure that drying oven thermometers are equipped with appropriate heat sinks to ensure that temperature readings do not fluctuate when opening and closing the oven door, and recommended they document accurate oven temperatures are maintained (see Photograph VWPC0005.jpg - drying oven with thermometer bulb located in open air). Mr. Gunter asked about the procedure for analyzing total suspended solids. After Mr. Majer described the process, Mr. Gunter explained that the process was not consistent with the approved standard method (Standard Method 2540D). He further explained that the analyses must include and document weighing to a constant weight, as required in the approved standard method. Section 3.C. of the approved standard method requires repeat cycles of drying, cooling, desiccating, and weighing until a constant weight is obtained or until the weight change is less than 4% of the previous weight or 0.5 mg, whichever is less. At this point we agreed to break for lunch and return at noon. Upon our return to the Facility, we met with Mr. Yost and he provided copies of SSO annual reports (required pursuant to Permit Part II.D.2.b.), for 2016, 2018, 2019, and 2020, requested earlier in the day. He could not locate the annual report for 2017 and was not sure it was submitted to Ohio EPA. To fill in for the missing report, he provided all SSO-related DMRs for 2017. We returned to the laboratory to take the photographs referenced above. Headworks: We left the Facility office and were joined by Mr. Yost, Mr. Fannin and Mr. Mayer for the physical inspection of the wastewater treatment system. Mr. Fannin explained the a third of the incoming sewage comes into the plant by gravity flow and through the twin screws (Photographs VWPC0006.jpg and VWPC0007.jpg), and the remaining flow comes into the plant via a force main from the River Lift Station. The west screw was running at the time and Mr. Fannin said they alternate screws monthly. Next we viewed the parshall flume designed to measure flow after the screws (Photograph VWPC0008.jpg). Mr. Yost stated that they do not monitor incoming flow at this location as it is not required by the permit. Next we walked along the influent flow channel to the point where sewage from the force main joins the gravity flow (Photograph VWPC0009.jpg) before heading into the bar screen building. We observed the operating bar screen (Photograph VWPC0010.jpg) and inoperable grit removal system 6 City of Vermilion WPCF CEI Inspection Report (Photograph VWPC0011.jpg). Operators were manually cleaning grit while the grit removal system is down for repairs. The bar screen building also houses the influent composite sampler (Century 3000). I noticed the inside of the influent sample hose tubing was coated with debris (Photograph VWPC0012.jpg) and recommended replacement or cleaning on a routine basis to avoid sample contamination. The inside of the influent composite sampler is captured in Photograph VWPC0013.jpg. Primary Clarifiers: Primary treatment consists of three primary clarifiers (Photograph VWPC0014.jpg, Clarifier #3 in foreground). Mr. Yost mentioned that Clarifier #3 was rebuilt two years ago, Clarifier #2 about seven years ago, and Clarifier #1 is due for a rebuild. I noted a PVC pipe with a significant flow of clear water appearing to flow into a grate-covered vault leading to the primary clarifiers (Photograph VWPC0015.jpg). Mr. Fannin explained that river water infiltrates the basement and is collected and pumped into the primary clarifiers to avoid flooding. Aeration: Wastewater aeration consists of four aeration tanks (Photograph VWPC0016.jpg, Aeration Tank #1 in foreground). Final Clarifiers: The final wastewater clarification system consists of six clarifiers (Photograph VWPC0017.jpg). Mr. Fannin explained that four clarifiers operate every day and one is shut down daily for routine maintenance. He added that Clarifier #6 is currently shut down for repairs. The rails in Clarifier #6 were rotted out (see the center area of Photograph VWPC0018.jpg) and they are waiting for new rail parts. I observed Clarifier #5 and noted significant debris and plant material (likely duckweed) in the effluent troughs and channels (Photograph VWPC0019.jpg). I asked if the clarifier had been cleaned recently and Mr. Yost replied that he was not sure and would make sure the clarifier is cleaned to remove the debris. I mentioned that at this point in the treatment process effluent exiting the clarifier should be free of visible debris. Disinfection: Facility wastewater disinfection relies on a liquid chlorine feed system (Photograph VWPC0020.jpg, chlorine feed pipe). After the chlorine feed, effluent flows into a chlorine contact tank. I noticed floating plant material (likely duckweed) at the end of the chlorine contact tank and at the point where chlorinated effluent flows to the final outfall, according to Mr. Yost (Photograph VWPC0021.jpg). I mentioned to Mr. Yost that significant debris at this point in the treatment process (only dechlorination remaining), has the potential to result in permit effluent exceedances, including total suspended solids. Sodium bisulfate is used for dechlorination (Photograph VWPC0022.jpg, dechlorination drip tubing in effluent channel after chlorine contact tank and prior to final outfall). Chemical Room: The chemical room contains process chemicals and the final effluent composite sampler (Hach, Photograph VWPC0023.jpg). I asked if the composite sampler is set up to collect time or flow-based composite samples. Mr. Fannin confirmed that the composite sampler is set up to collect flow-based samples, consistent with permit requirements. I noted that the sample container appeared to be heavily stained. I mentioned that the container should be cleaned routinely or replaced as needed, along with the effluent tubing. 7 City of Vermilion WPCF CEI Inspection Report Final Outfall 001: The final outfall (#001) to the Vermilion River was the last stop on the physical inspection of the Facility. The river appeared to be high and murky (see contrast between effluent discharge and river water in Photograph VWPC0024.jpg). III. D. Physical Inspection of Select SSO Locations We completed the physical inspection of the Facility wastewater treatment system at 1:35 p.m., and the group returned to the Facility office. Upon our return, I noticed copies of operator log books and photographed (VWPC0025.jpg) recent pages for 6/22-7/7/21. We then began the physical inspection of select SSO locations including the River Lift Station, Elberta Lift Station, and the Vermilion-on-the-Lake ("VOL") Lift Station (see Attachment E, July 14, 2021 Inspection Location Map). We were joined by Mr. Fennin, Mr. Mayer, and Mr. Yost. We started by driving to the River Lift Station, located in a private marina area. I observed the lift station components, including the wet well (Photograph VWPC0026.jpg). Mr. Fannin described what happens when SSO occurs at this location. He said SSOs discharge from a nearby manhole along the railroad track berm and flow towards an open area between the berm and marina access road. We could not locate the manhole due to security fencing and heavy vegetation in the berm area. He added that SSOs reach the marina waters only during extreme rain events. Next we drove to the Elberta Lift Station, which has a constructed outfall to Lake Erie. Mr. Fannin explained that when the lift station overflows the SSOs enter a sewer inlet (in the foreground of Photograph VWPC0027.jpg), and flows via a pipe to an outfall to Lake Erie. He added that SSOs occur at this location during heavy rains. Last, we drove to the VOL Lift Station area. Here, SSOs enter a stormwater catch basin along Edgewater Drive (Photograph VWPC0029.jpg), which flows via a pipe to an outfall to Lake Erie. At this point (2:20 p.m.), we concluded the physical inspection of select SSO locations and concluded the inspection activities for the day. We agreed to meet the next morning (July 15, 2021) at 8 a.m. to conduct the inspection close out conference. IV. CLOSING CONFERENCE, AREAS OF CONCERN, AND OTHER OBSERVATIONS Ken Gunter and I returned to the Facility office at 7:45 a.m. on July 15, 2021. We met with Mr. Yost in his office to conduct the closing conference. First we went over the status of documents I requested the previous day. Mr. Yost agreed to provide the SSO O&M Response Plan, collection system O&M plans, the Facility SWPPP, and the Water System Notification procedure by Wednesday, July 21, 2021. He also agreed to provide additional details on the collection system, including the number of sewer connections/customers, miles/feet of conveyance, and any sewer backup complaint logs by Wednesday, July 21, 2021. Next, I went over preliminary areas of concern, and noted that I may identify other areas of concern after further review of inspection notes and documents received as part of the inspection. 8 City of Vermilion WPCF CEI Inspection Report The preliminary areas of concern included: The Facility reported, via electronic DMRs submitted to Ohio EPA, 50 permit effluent limitation exceedances from June 2016 to May 2021. Reporting (non-DMR related) Areas of Concern: o The Ammonia-Nitrogen Reduction Evaluation was dated December 2, 2020, but due to Ohio EPA, pursuant to the Permit Part I.C.3.e., by December 1, 2019; o The Annual Mercury PMP report required pursuant to the permit was submitted by the March 1, 2021 deadline. However, the copy of the report provided was missing required information such as a list of potential mercury sources (Permit Part II.U.1.g.ii) and a summary of efforts to reduce mercury (Permit Part II.U.1.g.iii); o Pursuant to Permit Part I.C.5.e.ii., the Facility was required to submit a No Feasible Alternatives Analysis and Schedule ("NFA") regarding the reduction of I&I by December 1, 2019. Mr. Yost provided documentation including letters sent to Ohio EPA and a related Notice of Violation and correspondence from Ohio EPA discussing the Facility's failure to comply with Permit Part I.C.5.e.ii.; o Pursuant to Permit Part II.AA.3., written notification procedures between the Facility and the downstream public water supply system were required by June 1, 2016; The Facility was not aware of this requirement or if the procedures existed. On July 21, 2021, Mr. Yost provided a written notification procedure via email. However, the procedure was not dated and did not cover upsets, spills, and bypasses. He later confirmed that the procedure was recently developed; and o Facility representatives were unable to provide the Facility's SWPPP, required pursuant to Permit Part V, upon request. On July 21, 2021, Mr. Yost provided an update on the SWPPP status, explaining that it is currently being developed by a contract engineering firm. Operation and Maintenance Areas of Concern, noting that Permit Part III.3.A requires "[a]t all times, the permittee shall maintain in good working order and operate as efficiently as possible all treatment or control facilities or systems installed or used by the permittee necessary to achieve compliance with the terms and conditions of this permit." o Two of the six final clarifiers were down from 2018 to October 2020; o Effluent limit exceedances in October 2020, including TSS, nitrogen-ammonia total (as N), and E. coli; and TSS exceedances in February 2021 were attributed to air lift issues and insufficient air to support aeration; o Phosphorus effluent limit exceedance in February 2021 were attributed to a ferrous chloride system pump failure; o For most of the past year, the Facility operated without the use of all six clarifiers and insufficient air support aeration, and is currently operating with without Clarifier #6 and the grit removal unit; o According to Mr. Yost, I&I is the biggest issue leading to compliance issues with average daily flows of approximately 1 MGD and peak daily flows of up to 6.5 MGD; o Clear river water is infiltrating into the Facility basement and pumped to the primary clarifiers, adding to amount of non-sanitary flow being treated at the Facility; o Inside of the influent sample hose tubing was coated with debris; o Clarifier #6 is currently offline due to rotted rails. Facility is waiting for new parts. 9 City of Vermilion WPCF CEI Inspection Report o I observed significant debris and plant material (likely duckweed) in the effluent troughs and channels in Clarifier #5; o I observed floating plant material (likely duckweed) at the end of the chlorine contact tank, at the point where treated effluent exits the chlorine tank; and o The effluent sample container appeared to be heavily stained. The container should be cleaned routinely or replaced as needed, along with the effluent tubing. SSOs (all SSOs are prohibited as stated in Permit Part I.B.): o The Facility reported, via electronic DMRs submitted to Ohio EPA, 64 SSOs from February 2017 to May 2021; o Facility representatives could not locate the SSO annual report for 2017 and were not sure if it was submitted to Ohio EPA, as required pursuant to Permit Part II.D.2.b.iii.. Laboratory Areas of Concern: o Laboratory bench sheets do not include dates and times for both sample collection and analysis to allow for confirmation of holding times; o Chain-of-custody form provided for July 1, 2021 did not allow for tracking of custody of a sample from the time of collection (June 22, 2021) to the time the sample was delivered to the laboratory on July 1, 2021; o Drying oven thermometers are not equipped with appropriate heat sinks to ensure that temperature readings do not fluctuate when opening and closing the oven door, and oven temperatures records are not maintained; and o TSS analytical process is not consistent with the approved standard method (Standard Method 2540D). The analyses must include and document weighing to a constant weight, as required in the standard method. Section 3.C. of the standard method requires repeat cycles of drying, cooling, desiccating and weighing until a constant weight is obtained or until the weight change is less than 4% of the previous weight or 0.5 mg, whichever is less. Additional laboratory-related observations include: Careful review of contract laboratory case narratives. Case narratives are an important part of the data deliverables from a contract laboratory. The case narrative is typically a short summary statement about the analyses that might include the number and type of samples analyzed. Any significant receipt, analysis, or QA/QC problem should be documented in this section. The case narrative may not actually be called a "case narrative" but is the explanatory text at or near the beginning of the data package. The data user should carefully read this part of the report, as it helps identify problem samples or problem analyses that could lead to limitations on the use of the data or, in extreme cases, data rejection. Laboratory personnel should maintain an instrument log documenting replacement, cleaning, checking, and/or adjustment by service personnel for all laboratory instruments and all outof-control data, the situation, and the corrective action taken. Laboratory personnel should perform annual Method Detection Limit (MDL) studies for all in house analyses (Ammonia, phosphorus, Total Residual Chlorine and Total Suspended Solids). The procedure to determine MDL's was revised in the 2017 Method Update Rule and is included in Attachment D. 10 City of Vermilion WPCF CEI Inspection Report After sharing the preliminary areas of concern, I asked Mr. Yost if he had any questions. With no questions from Mr. Yost, I provided an estimated timeframe for completion of the inspection report and we concluded the closing conference. We departed the Facility at 8:45 a.m. on July 15, 2021. V. DOCUMENTS RECEIVED AND REFERENCES Documents received during the inspection: Laboratory narrative and chain-of-custody forms (9/9/2020); Laboratory chain-of-custody form (7/1/2021); Ohio EPA compliance sampling inspection report, dated 9/30/2019; Ohio EPA Notice of Violation ("NOV"), dated 12/29/2020; City of Vermilion letter to Ohio EPA, regarding SSO NFA, dated 12/17/2020; City of Vermilion letter to Ohio EPA, dated January 28, 2021, regarding Ohio EPA NOV, dated 12/29/2020; Ohio EPA letter to City of Vermilion regarding SSO NFA and permit modification, dated 2/9/2021; Mercury PMP Annual Report, dated 3/2/2021; Ammonia-Nitrogen Reduction Evaluation, dated 12/2/2020; and SSO Annual Reports (2016-2018, 2019-2020), SSO-related DMRs for 2017; and SSO 5-day reports for 3/5/2021, 5/11/2021, and 6/10/2021. Specific resources included by reference: City of Vermilion WPCF NPDES Permit# OH-0023612 (Ohio ID# 2PD00032*MD); issued by Ohio EPA on December 1, 2016 ; expiration date November 30, 2021; Fact Sheet: City of Vermilion WPCF NPDES Permit# OH-0023612 (Ohio ID# 2PD00032*MD), Public Notice Date - July 29, 2016. 11 City of Vermilion WPCF CEI Inspection Report Attachment A: Diagram of the Facility wastewater treatment system City of Vermilion WPCF CEI Inspection Report [This page intentionally left blank] Attachment B: Documents received during the inspection Laboratory narrative and Chain-of-Custody forms (9/9/2020); Laboratory Chain-of-Custody form (7/1/2021); Ohio EPA compliance sampling inspection report, dated 9/30/2019 Ohio EPA NOV, dated 12/29/2020; City of Vermilion letter to Ohio EPA, regarding SSO NFA, dated 12/17/2020; City of Vermilion letter to Ohio EPA, dated January 28, 2021, regarding Ohio EPA NOV, dated 12/29/2020; Ohio EPA letter to City of Vermilion regarding SSO NFA and permit modification, dated 2/9/2021; Mercury PMP Annual Report, dated 3/2/2021; Ammonia-Nitrogen Reduction Evaluation, dated 12/2/2020; and SSO Annual Reports (2016-2018, 2019-2020), and SSO-related DMRs for 2017; and SSO 5-day reports for 3/5/2021, 5/11/2021, and 6/10/2021. 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page-89 City of Vermilion WPCF CEI Inspection Report Attachment B, page-90 City of Vermilion WPCF CEI Inspection Report Attachment B, page-91 City of Vermilion WPCF CEI Inspection Report Attachment B, page-92 City of Vermilion WPCF CEI Inspection Report Attachment B, page-93 City of Vermilion WPCF CEI Inspection Report Attachment B, page-94 City of Vermilion WPCF CEI Inspection Report Attachment B, page-95 City of Vermilion WPCF CEI Inspection Report Attachment B, page-96 City of Vermilion WPCF CEI Inspection Report Attachment B, page-97 City of Vermilion WPCF CEI Inspection Report Attachment B, page-98 City of Vermilion WPCF CEI Inspection Report Attachment B, page-99 City of Vermilion WPCF CEI Inspection Report Attachment B, page-100 City of Vermilion WPCF CEI Inspection Report Attachment B, page-101 City of Vermilion WPCF CEI Inspection Report Attachment B, page-102 City of Vermilion WPCF CEI Inspection Report Attachment B, page-103 City of Vermilion WPCF CEI Inspection Report Attachment B, page-104 City of Vermilion WPCF CEI Inspection Report Attachment B, page-105 City of Vermilion WPCF CEI Inspection Report Attachment B, page-106 City of Vermilion WPCF CEI Inspection Report Attachment B, page-107 City of Vermilion WPCF CEI Inspection Report Attachment C: Photo Log City of Vermilion WPCF EPA Inspection July 14-15, 2021 All photos taken by Dean Maraldo, Inspector, U.S. EPA Camera: Ricoh WG-4 1: VWPC0001 Description: Analytical scale calibration certification. Location: Laboratory Camera Direction: 340 Date/Time: July 14, 2021; 12:27 p.m. Attachment C, page 1 City of Vermilion WPCF CEI Inspection Report 2: VWPC0002 Description: Updated laboratory SOPs. Location: Laboratory Camera Direction: 234 Date/Time: July 14, 2021; 12:28 p.m. 3: VWPC0003 Description: Laboratory bench sheets. Location: Laboratory Camera Direction: 1 Date/Time: July 14, 2021; 12:29 p.m. Attachment C, page 2 City of Vermilion WPCF CEI Inspection Report 4: VWPC0004 Description: Buffer solutions documenting opening and expiration dates. Location: Laboratory Camera Direction: 275 Date/Time: July 14, 2021; 12:30 p.m. 5: VWPC0005 Description: Drying oven with thermometer bulb located in open air. Location: Laboratory Camera Direction: 344 Date/Time: July 14, 2021; 12:31 p.m. Attachment C, page 3 City of Vermilion WPCF CEI Inspection Report 6: VWPC0006 Description: Twin screws pushing incoming gravity flow. Location: Headworks Camera Direction: 348 Date/Time: July 14, 2021; 12:35 p.m. 7: VWPC0007 Description: Twin screws pushing incoming gravity flow. Location: Headworks Camera Direction: 348 Date/Time: July 14, 2021; 12:36 p.m. Attachment C, page 4 City of Vermilion WPCF CEI Inspection Report 8: VWPC0008 Description: Parshall flume designed to measure flow after the screws. Location: Headworks Camera Direction: 240 Date/Time: July 14, 2021; 12:42 p.m. 9: VWPC0009 Description: Influent flow channel and the point where sewage from the force main joins the gravity flow. Location: Headworks Camera Direction: 288 Date/Time: July 14, 2021; 12:44 p.m. Attachment C, page 5 City of Vermilion WPCF CEI Inspection Report 10: VWPC0010 Description: Operating bar screen. Location: Headworks; bar screen building Camera Direction: 157 Date/Time: July 14, 2021; 12:47 p.m. 11: VWPC0011 Description: Inoperable grit removal system. Location: Headworks; bar screen building Camera Direction: 314 Date/Time: July 14, 2021; 12:47 p.m. Attachment C, page 6 City of Vermilion WPCF CEI Inspection Report 12: VWPC0012 Description: Influent composite sampler (Century 3000). was coated with debris. Location: Headworks; bar screen building Camera Direction: 21 Date/Time: July 14, 2021; 12:48 p.m. Note the inside of the influent sample tubing 13: VWPC0013 Description: Inside of the influent composite sampler. Location: Headworks; bar screen building Camera Direction: 50 Date/Time: July 14, 2021; 12:48 p.m. Attachment C, page 7 City of Vermilion WPCF CEI Inspection Report 14: VWPC0014 Description: Primary treatment consists of three primary clarifiers. Clarifier #3 in foreground. Location: Primary clarifier area Camera Direction: 230 Date/Time: July 14, 2021; 12:53 p.m. 15: VWPC0015 Description: Clear river water pumped from the basement and likely due to river infiltration into basement. Piped to the primary clarifiers. Location: Primary clarifier area Camera Direction: 76 Date/Time: July 14, 2021; 12:55 p.m. Attachment C, page 8 City of Vermilion WPCF CEI Inspection Report 16: VWPC0016 Description: Aeration tanks. Aeration Tank #1 in foreground. Location: Secondary treatment area Camera Direction: 201 Date/Time: July 14, 2021; 1:00 p.m. 17: VWPC0017 Description: Final clarifiers. Location: Secondary clarifier area Camera Direction: 265 Date/Time: July 14, 2021; 1:04 p.m. Attachment C, page 9 City of Vermilion WPCF CEI Inspection Report 18: VWPC0018 Description: Final Clarifier #6. The rails were rotted out (see the center area of photograph). Location: Secondary clarifier area Camera Direction: 255 Date/Time: July 14, 2021; 1:08 p.m. 19: VWPC0019 Description: Clarifier #5. Noted significant debris and plant material (likely duckweed) in the effluent troughs and channels. Location: Secondary clarifier area Camera Direction: 334 Date/Time: July 14, 2021; 1:09 p.m. Attachment C, page 10 City of Vermilion WPCF CEI Inspection Report 20: VWPC0020 Description: Liquid chlorine feed system. Note white feed pipe under channel grate cover. Location: Disinfection area Camera Direction: 46 Date/Time: July 14, 2021; 1:11 p.m. 21: VWPC0021 Description: Floating plant material (likely duckweed) at the end of the chlorine contact tank, at the point where treated effluent exits the chlorine tank. Location: Disinfection area Camera Direction: 215 Date/Time: July 14, 2021; 1:13 p.m. Attachment C, page 11 City of Vermilion WPCF CEI Inspection Report 22: VWPC0022 Description: Dechlorination drip tubing in effluent channel after chlorine contact tank and prior to final outfall. Location: Disinfection area Camera Direction: 60 Date/Time: July 14, 2021; 1:16 p.m. 23: VWPC0023 Description: Final effluent composite sampler (Hach). Note staining in sample container. Location: Chemical room Camera Direction: 340 Date/Time: July 14, 2021; 1:22 p.m. Attachment C, page 12 City of Vermilion WPCF CEI Inspection Report 24: VWPC0024 Description: The final outfall (#001) to the Vermilion River. (see contrast between effluent discharge and river water). Location: Final outfall to the Vermilion River Camera Direction: 22 Date/Time: July 14, 2021; 1:26 p.m. The river appeared to be high and murky 25: VWPC0025 Description: Operators log book, open to recent pages for 6/22/2021-7/7/2021. Location: Facility office Camera Direction: 315 Date/Time: July 14, 2021; 1:34 p.m. Attachment C, page 13 City of Vermilion WPCF CEI Inspection Report 26: VWPC0026 Description: Lift station wet well. Location: River Lift Station Camera Direction: 354 Date/Time: July 14, 2021; 1:43 p.m. 27: VWPC0027 Description:Lift station where overflows enter the sewer inlet in the foreground of photograph and flows via a pipe to an outfall to Lake Erie. Location: Elberta Lift Station Camera Direction: 171 Date/Time: July 14, 2021; 2:03 p.m. Attachment C, page 14 City of Vermilion WPCF CEI Inspection Report 28: VWPC0028 Description: SSOs in this area enter the stormwater catch basin (in the foreground of photograph), along Edgewater Drive. The inlet sends flow through a pipe to an outfall to Lake Erie (behind the homes in the photograph). Location: VOL Lift Station area Camera Direction: 43 Date/Time: July 14, 2021; 2:17 p.m. Attachment C, page 15 City of Vermilion WPCF CEI Inspection Report City of Vermilion WPCF CEI Inspection Report [This page intentionally left blank] Attachment D: 2017 Method Update Rule Attachment D, page-1 City of Vermilion WPCF CEI Inspection Report Office of Water www.epa.gov EPA 821-R-16-006 December 2016 Definition and Procedure for the Determination of the Method Detection Limit, Revision 2 Attachment D, page-2 City of Vermilion WPCF CEI Inspection Report This document contains the text of Revision 2 of the method detection limit procedure from 40 CFR 136 Appendix B; but formatted as a more user friendly stand-alone document. Please address questions or comments to: CWA Methods Team Engineering and Analytical Support Branch/EAD (4303T) Office of Science and Technology U.S. Environmental Protection Agency 1200 Pennsylvania Avenue Washington, DC 20460 https://www.epa.gov/cwa-methods Attachment D, page-3 City of Vermilion WPCF CEI Inspection Report DEFINITION AND PROCEDURE FOR THE DETERMINATION OF THE METHOD DETECTION LIMIT REVISION 2 Definition The method detection limit (MDL) is defined as the minimum measured concentration of a substance that can be reported with 99% confidence that the measured concentration is distinguishable from method blank results. Scope and Application The MDL procedure is designed to be a straightforward technique for estimation of the detection limit for a broad variety of physical and chemical methods. The procedure requires a complete, specific, and welldefined analytical method. It is essential that all sample processing steps used by the laboratory be included in the determination of the method detection limit. The MDL procedure is not applicable to methods that do not produce results with a continuous distribution, such as, but not limited to, methods for whole effluent toxicity, presence/absence methods, and microbiological methods that involve counting colonies. The MDL procedure also is not applicable to measurements such as, but not limited to, biochemical oxygen demand, color, pH, specific conductance, many titration methods, and any method where low-level spiked samples cannot be prepared. Except as described in the addendum, for the purposes of this procedure, "spiked samples" are prepared from a clean reference matrix, such as reagent water, spiked with a known and consistent quantity of the analyte. MDL determinations using spiked samples may not be appropriate for all gravimetric methods (e.g., residue or total suspended solids), but an MDL based on method blanks can be determined in such instances. Procedure (1) Estimate the initial MDL using one or more of the following: (a) The mean determined concentration plus three times the standard deviation of a set of method blanks. (b) The concentration value that corresponds to an instrument signal-to-noise ratio in the range of 3 to 5. (c) The concentration equivalent to three times the standard deviation of replicate instrumental measurements of spiked blanks. (d) That region of the calibration where there is a significant change in sensitivity, i.e., a break in the slope of the calibration. (e) Instrumental limitations. (f) Previously determined MDL. It is recognized that the experience of the analyst is important to this process. However, the analyst should include some or all of the above considerations in the initial estimate of the MDL. Attachment D, page-4 City of Vermilion WPCF CEI Inspection Report (2) Determine the initial MDL Note: The Initial MDL is used when the laboratory does not have adequate data to perform the Ongoing Annual Verification specified in Section (4), typically when a new method is implemented or if a method was rarely used in the last 24 months. (a) Select a spiking level, typically 2 - 10 times the estimated MDL in Section 1. Spiking levels in excess of 10 times the estimated detection limit may be required for analytes with very poor recovery (e.g., for an analyte with 10% recovery, spiked at 100 micrograms/L, with mean recovery of 10 micrograms/L; the calculated MDL may be around 3 micrograms/L. Therefore, in this example, the spiking level would be 33 times the MDL, but spiking lower may result in no recovery at all). (b) Process a minimum of seven spiked samples and seven method blank samples through all steps of the method. The samples used for the MDL must be prepared in at least three batches on three separate calendar dates and analyzed on three separate calendar dates. (Preparation and analysis may be on the same day.) Existing data may be used, if compliant with the requirements for at least three batches, and generated within the last twenty four months. The most recent available data for method blanks and spiked samples must be used. Statistical outlier removal procedures should not be used to remove data for the initial MDL determination, since the total number of observations is small and the purpose of the MDL procedure is to capture routine method variability. However, documented instances of gross failures (e.g., instrument malfunctions, mislabeled samples, cracked vials) may be excluded from the calculations, provided that at least seven spiked samples and seven method blanks are available. (The rationale for removal of specific outliers must be documented and maintained on file with the results of the MDL determination.) (i) If there are multiple instruments that will be assigned the same MDL, then the sample analyses must be distributed across all of the instruments. (ii) A minimum of two spiked samples and two method blank samples prepared and analyzed on different calendar dates is required for each instrument. Each analytical batch may contain one spiked sample and one method blank sample run together. A spiked sample and a method blank sample may be analyzed in the same batch, but are not required to be. (iii) The same prepared extract may be analyzed on multiple instruments so long as the minimum requirement of seven preparations in at least three separate batches is maintained. (c) Evaluate the spiking level: If any result for any individual analyte from the spiked samples does not meet the method qualitative identification criteria or does not provide a numerical result greater than zero, then repeat the spiked samples at a higher concentration. (Qualitative identification criteria are a set of rules or guidelines for establishing the identification or presence of an analyte using a measurement system. Qualitative identification does not ensure that quantitative results for the analyte can be obtained.) (d) Make all computations as specified in the analytical method and express the final results in the method-specified reporting units. (i) Calculate the sample standard deviation (S) of the replicate spiked sample measurements and the sample standard deviation of the replicate method blank measurements from all instruments to which the MDL will be applied. Attachment D, page-5 City of Vermilion WPCF CEI Inspection Report (ii) Compute the MDLs (the MDL based on spiked samples) as follows: = (-1, 1-=0.99) where: MDLs = the method detection limit based on spiked samples t(n-1, 1- = 0.99) = the Student's t-value appropriate for a single-tailed 99th percentile t statistic and a standard deviation estimate with n-1 degrees of freedom. See Addendum Table 1. Ss = sample standard deviation of the replicate spiked sample analyses. (iii) Compute the MDLb (the MDL based on method blanks) as follows: (A) If none of the method blanks give numerical results for an individual analyte, the MDLb does not apply. A numerical result includes both positive and negative results, including results below the current MDL, but not results of "ND" (not detected) commonly observed when a peak is not present in chromatographic analysis. (B) If some (but not all) of the method blanks for an individual analyte give numerical results, set the MDLb equal to the highest method blank result. If more than 100 method blanks are available, set MDLb to the level that is no less than the 99th percentile of the method blank results. For "n" method blanks where n 100, sort the method blanks in rank order. The (n * 0.99) ranked method blank result (round to the nearest whole number) is the MDLb. For example, to find MDLb from a set of 164 method blanks where the highest ranked method blank results are ... 1.5, 1.7, 1.9, 5.0, and 10, then 164 x 0.99 = 162.36 which rounds to the 162nd method blank result. Therefore, MDLb is 1.9 for n =164 (10 is the 164th result, 5.0 is the 163rd result, and 1.9 is the 162nd result). Alternatively, you may use spreadsheet algorithms to calculate the 99th percentile to interpolate between the ranks more precisely. (C) If all of the method blanks for an individual analyte give numerical results, then calculate the MDLb as: = + (-1,1-=0.99) where: MDLb t(n-1, 1- = 0.99) Sb = the MDL based on method blanks = mean of the method blank results (use zero in place of the mean if the mean is negative) = the Student's t-value appropriate for the single-tailed 99th percentile t statistic and a standard deviation estimate with n-1 degrees of freedom. See Addendum Table 1. = sample standard deviation of the replicate method blank sample analyses. Note: If 100 or more method blanks are available, as an option, MDLb may be set to the concentration that is greater than or equal to the 99th percentile of the method blank results, as described in Section (2)(d)(iii)(B). (e) Select the greater of MDLs or MDLb as the initial MDL. Attachment D, page-6 City of Vermilion WPCF CEI Inspection Report (3) Ongoing Data Collection (a) During any quarter in which samples are being analyzed, prepare and analyze a minimum of two spiked samples on each instrument, in separate batches, using the same spiking concentration used in Section 2. If any analytes are repeatedly not detected in the quarterly spiked sample analyses, or do not meet the qualitative identification criteria of the method (see Section 2(c) of this procedure), then this is an indication that the spiking level is not high enough and should be adjusted upward. Note that it is not necessary to analyze additional method blanks together with the spiked samples, the method blank population should include all of the routine method blanks analyzed with each batch during the course of sample analysis. (b) Ensure that at least seven spiked samples and seven method blanks are completed for the annual verification. If only one instrument is in use, a minimum of seven spikes are still required, but they may be drawn from the last two years of data collection. (c) At least once per year, re-evaluate the spiking level. (i) If more than 5% of the spiked samples do not return positive numerical results that meet all method qualitative identification criteria, then the spiking level must be increased and the initial MDL re-determined following the procedure in Section 2. (d) If the method is altered in a way that can be reasonably expected to change its sensitivity, then redetermine the initial MDL according to Section 2, and the restart the ongoing data collection. (e) If a new instrument is added to a group of instruments whose data are being pooled to create a single MDL, analyze a minimum of two spiked replicates and two method blank replicates on the new instrument. If both method blank results are below the existing MDL, then the existing MDLb is validated. Combine the new spiked sample results to the existing spiked sample results and recalculate the MDLs as in Section 4. If the recalculated MDLs does not vary by more than the factor specified in Section 4(f) of this procedure, then the existing MDLs is validated. If either of these two conditions is not met, then calculate a new MDL following the instructions in Section 2. (4) Ongoing Annual Verification (a) At least once every thirteen months, re-calculate MDLs and MDLb from the collected spiked samples and method blank results using the equations in Section 2. (b) Include data generated within the last twenty four months, but only data with the same spiking level. Only documented instances of gross failures (e.g., instrument malfunctions, mislabeled samples, cracked vials) may be excluded from the calculations. (The rationale for removal of specific outliers must be documented and maintained on file with the results of the MDL determination.) If the laboratory believes the sensitivity of the method has changed significantly, then the most recent data available may be used, maintaining compliance with the requirement for at least seven replicates in three separate batches on three separate days (see Section 2b). (c) Include the initial MDL spiked samples, if the data were generated within twenty four months. (d) Only use data associated with acceptable calibrations and batch QC. Include all routine data, with the exception of batches that are rejected and the associated samples reanalyzed. If the method has been altered in a way that can be reasonably expected to change its sensitivity, then use only data collected after the change. Attachment D, page-7 City of Vermilion WPCF CEI Inspection Report (e) Ideally, use all method blank results from the last 24 months for the MDLb calculation. The laboratory has the option to use only the last six months of method blank data or the fifty most recent method blanks, whichever criteria yields the greater number of method blanks. (f) The verified MDL is the greater of the MDLs or MDLb. If the verified MDL is within 0.5 to 2.0 times the existing MDL, and fewer than 3% of the method blank results (for the individual analyte) have numerical results above the existing MDL, then the existing MDL may optionally be left unchanged. Otherwise, adjust the MDL to the new verification MDL. (The range of 0.5 to 2.0 approximates the 95th percentile confidence interval for the initial MDL determination with six degrees of freedom.) ADDENDUM: DETERMINATION OF THE MDL FOR A SPECIFIC MATRIX The MDL may be determined in a specific sample matrix as well as in reagent water. (1) Analyze the sample matrix to determine the native (background) concentration of the analyte(s) of interest. (2) If the response for the native concentration is at a signal-to-noise ratio of approximately 5-20, determine the matrix-specific MDL according to Section 2 but without spiking additional analyte. (3) Calculate MDLb using the method blanks, not the sample matrix. (4) If the signal-to-noise ratio is less than 5, then the analyte(s) should be spiked into the sample matrix to obtain a concentration that will give results with a signal-to-noise ratio of approximately 10-20. (5) If the analytes(s) of interest have signal-to-noise ratio(s) greater than approximately 20, then the resulting MDL is likely to be biased high. Table 1: Single-Tailed 99th Percentile t Statistic Number of replicates Degrees of freedom (n-1) t (n-1, 0.99) 7 6 3.143 8 7 2.998 9 8 2.896 10 9 2.821 11 10 2.764 16 15 2.602 21 20 2.528 26 25 2.485 31 30 2.457 32 31 2.453 48 47 2.408 50 49 2.405 61 60 2.390 64 63 2.387 80 79 2.374 96 95 2.366 100 99 2.365 Attachment D, page-8 City of Vermilion WPCF CEI Inspection Report Documentation The analytical method used must be specifically identified by number or title and the MDL for each analyte expressed in the appropriate method reporting units. Data and calculations used to establish the MDL must be able to be reconstructed upon request. The sample matrix used to determine the MDL must also be identified with MDL value. Document the mean spiked and recovered analyte levels with the MDL. The rationale for removal of outlier results, if any, must be documented and maintained on file with the results of the MDL determination. Attachment D, page-9 City of Vermilion WPCF CEI Inspection Report City of Vermilion WPCF CEI Inspection Report Attachment E: July 14, 2021 Inspection Location Map City of Vermilion WPCF CEI Inspection Report [This page intentionally left blank]