Document O1rq6BQ5a60ZdLp82LyZVL4Dw

U.S. ENVIRONMENTAL PROTECTION AGENCY REGION VIII WATER BRANCH, ENFORCEMENT AND COMPLIANCE ASSURANCE DIVISION CLEAN WATER ACT COMPLIANCE INSPECTION REPORT for Name of Facility: Town of Milliken Reverse Osmosis Water Treatment Plant Facility Address: 400 Inez Blvd., Milliken, CO 80543 Mailing Address: 400 Inez Blvd., Milliken, CO 80543 Report Prepared on: 7/28/2022 Date By:(b) (6) Danny O'Connell, Environmental Scientist (PG Environmental) Signature Report Final as of: 8/24/2022 Date By: , EPA Signature Michael Boeglin, Supervisor, EPA Region 8 General Information Type of Inspection: Reverse Osmosis Water Treatment Plant CEI Owner: Town of Milliken (Public) Operator: Town of Milliken Public Works Permittee: Milliken Reverse Osmosis Water Treatment Plant CDPS Permit No: CO0046485 CDPS Permit Effective Date: Issued November 23, 2015, became effective January 1, 2016. Modified September 30, 2020, modified Permit became effective November 1, 2020 CDPS Permit Expiration Date: December 31, 2020 (administratively extended) Number of Outfalls: 1 (Outfall 001A): 40.319 N, 104.864 W (At the Facility, also known as sampling Port 104) Receiving Water: Little Thompson River Latitude and Longitude: 40.32143 N 104.86779 W (Discharge point to the river) On-Site Facility Inspection Overview Inspection Date: June 21, 2022 Approximate Entry Time: 9:00 a.m. (MDT) Approximate Exit Time: 1:00 p.m. (MDT) On June 21, 2022, a representative from U.S. Environmental Protection Agency (EPA) Region VIII, the Colorado Department of Public Health and Environment (CDPHE), and EPA's contract inspectors from PG Environmental (the EPA Inspection Team), conducted a compliance evaluation inspection of wastewater discharges from the Milliken Reverse Osmosis Water Treatment Plant (ROWTP) in Milliken, Colorado. The Town of Milliken Public Works is identified as the Permittee and owns and operates the Facility. The ROWTP was completely offline at the time of inspection. Page 1 of 12 Inspection Dates: June 21, 2022 Town of Milliken Reverse Osmosis Water Treatment Plant (CO0046485) Compliance Evaluation Inspection Report TABLE OF CONTENTS I. INTRODUCTION............................................................................................................................ 3 Facility Description..........................................................................................................................3 Wastewater Generation and Treatment ............................................................................................4 Wastewater Monitoring and Flow....................................................................................................5 Wastewater Solids Handling ............................................................................................................5 WWTP Operation and Maintenance Management ..........................................................................6 II. INSPECTION PROCESS ................................................................................................................ 6 Inspection Opening Conference .......................................................................................................6 Inspection Attendee List: .................................................................................................................6 Facility Site Walk.............................................................................................................................6 Records Review ...............................................................................................................................9 III. SUMMARY OF OBSERVATIONS ................................................................................................ 9 IV. CLOSING CONFERENCE ........................................................................................................... 12 List of Attachments Appendix A: Photograph Log Appendix B: Exhibit Log o Exhibit 1 - SeHAWK Maintenance Log o Exhibit 2 - Milliken ROWTP Process Flow Diagram o Exhibit 3 - Integrated Compliance Information System (ICIS) Effluent Exceedance Data (March 1, 2019, through March 31, 2022) o Exhibit 4 - EPA's Enforcement and Compliance History Online (ECHO) Effluent Exceedance Data (March 1, 2019, through March 31, 2022) o Exhibit 5 - ROWTP Monthly Discharge Graph September 2019 to October 2021 o Exhibit 6 - January 2020 Whited-Out Daily Lab Worksheet Appendix C: CDPS Permit No. CO0046485 Page 2 of 12 Inspection Date: June 21, 2022 Town of Milliken Reverse Osmosis Water Treatment Plant (CO0046485) Compliance Evaluation Inspection Report I. INTRODUCTION On June 21, 2022, a representative from U.S. Environmental Protection Agency (EPA) Region VIII, the Colorado Department of Public Health and Environment (CDPHE), and EPA's contract inspectors from PG Environmental (hereinafter, collectively referred to as the EPA Inspection Team) inspected the Milliken Reverse Osmosis Water Treatment Plant (ROWTP) (hereinafter, Facility) in Milliken, Colorado. The Town of Milliken Public Works, (hereinafter, Permittee) is identified as the Permittee and owns and operates the Facility. The primary purpose of the inspection was to review and evaluate Facility operations and wastewater management, to review the accuracy and reliability of the Permittee's self-monitoring and reporting program, and to obtain information that will assist EPA in assessing the Permittee's compliance with the requirements of the Permit. The weather at the time of the inspection was breezy, warm, and sunny. The Facility was completely offline at the time of the inspection. The Facility is authorized to discharge process wastewater to the Little Thompson River (40.319 N, 104.864 W) consistent with the terms and conditions of Colorado Discharge Permit System (CDPS) Permit No. CO0046485 (hereinafter, the Permit). The Permit was issued on November 23, 2015 and became effective January 1, 2016. The Permit was modified September 30, 2020, and the modified Permit became effective November 1, 2020. The Permit expired on December 31st, 2020 but has been administratively extended. Photographs taken during the inspection are maintained on file with EPA Region VIII, some of which are included in this report as Appendix A, Photograph Log. Supporting documentation is included in Appendix B, Exhibit Log. A copy of the Permit is included as Appendix C. Facility Description The Facility uses Reverse Osmosis (RO) and carbon media bioreactor technology to treat groundwater that is pumped from two groundwater wells into the treatment system. The treated water is ultimately used as a drinking water source for the Town of Milliken and based on projected future demand projections, it is a critical source of water for the community. The Facility is located on the corner of County Road 21 and County Road 36 in Milliken, Colorado within Weld County. The drinking water aspect of the Facility is not covered under the CDPS Permit No. CO0046485 discussed in this report, but the process waste streams generated from the drinking water production are. Prior to 2014, the Facility was using only RO technology to treat groundwater. The Facility discharged its RO generated waste concentrate from the drinking water treatment process without further treatment. In response to a CDPHE Notice of Violation and Cease and Desist Order (numbers DO-140507-1 and IO140507-1, dated May 7, 2014) based on numerous selenium violations, additional technologies were brought in to try to reduce selenium concentrations in the waste streams produced from the RO treated groundwater processes. The Facility was shut down in 2014, and during the shutdown a pilot version of Frontier's SeHAWK bioreactor was brought into the Facility for testing. Facility representatives stated that the pilot version of the SeHAWK reduced selenium during the pilot study, so a full version of the bioreactor was brought online at the Facility in September 2019. Technical information about the SeHAWK can be found on Frontier's website using the following web link: https://frontierwater.com/sehawk-process/. Since the new bioreactor was placed into operation at the Facility in September 2019, it experienced structural challenges and failures which were tracked in the internal SeHAWK bioreactor maintenance log (refer to Appendix B, Exhibit 1). In June 2020, the bioreactor was taken offline due to a leak in the side of the tank. Operators stated that water was observed spraying out of the side of the tank, and it was shut down immediately. Also at this time, the underdrain of the tank was experiencing structural failures. Once repairs were made to the system, the bioreactor went back online in September 2020, before ultimately experiencing a gasket/seal failure which caused carbon to leak into the rest of the treatment system in Page 3 of 12 Inspection Date: June 21, 2022 Town of Milliken Reverse Osmosis Water Treatment Plant (CO0046485) Compliance Evaluation Inspection Report January 2021. The seals were replaced, but in October 2021 the bioreactor was shut down again because one of the underdrain plates experienced a structural failure. The seal between the metal drain plates and the bottom of the bioreactor failed during operation. This caused carbon to leak through bolt holes and get into the improper treatment units. The bioreactor has been shut down since the October 2021 failure, and new underdrain plates were being installed at the time of the inspection. The Facility's raw water source, two groundwater wells, are approximately 50 feet deep, and are positioned close together. The well's production rate and water quality can vary during normal operation. This is due to a varying recharge rate that at times is not high enough to maintain constant flow through the treatment process. Facility representatives speculate that this is one of the primary reasons that the bioreactor failed initially a few months after it was installed and continued to fail several times before being taken offline again in October 2021. The waste stream generated from the RO process consists of concentrate and various permeate flows. The waste stream from the RO process contributes approximately 0.14 MGD to the overall wastewater at the Facility, and the bioreactor generates approximately 0.17 MGD. Combined, the Facility is capable of producing 0.31 MGD of discharge. This is reflected in the Permittee's September 2020 Permit modification request to CDPHE in which the Facility successfully requested that their permitted flow be reduced from the Facility's designed capacity of 0.70 MGD to 0.31 MGD. The treated waste stream is monitored immediately downstream of the Facility's Reaction/Aeration tank. This location is identified as sampling Port 104 internally at the Facility, but also represents permitted Outfall 001A. Treated effluent is then gravity fed into a sump tank, where it is ultimately pumped to the Little Thompson River. The effluent is transported to the Little Thompson River by the town's stormwater line, which runs along the west side of South Quentine Avenue. It reaches the surface at a stormwater collector apron, where it comingles with stormwater before flowing to its final discharge point at the Little Thompson River. Solid waste generated at the Facility is removed for proper disposal by McDonald Farms Enterprises. Wastewater Generation and Treatment Wastewater streams (concentrate and maintenance streams) are generated at this Facility through Reverse Osmosis treatment during the process of generating drinking water for the Town of Milliken. At the start of the process, groundwater is drawn from two, approximately 50-foot-deep wells and blended. It is then sent through the one functional RO system, consisting of six individual units, for initial treatment. After RO treatment, brine concentrate and percentage of permeate are fed into an equalization tank. Some permeate from the RO process is sent to two, 1,100-gallon onsite holding tanks, where it is stored for future use during clean in place (CIP) operations. During periods of peak flow, such as summer, the Facility is able to completely fill the equalization tank before it is sent through the treatment system. During periods of lower flow like winter, according to Facility representatives the Facility is not able to generate a continuous stream of wastewater for the proper operation of the waste treatment system. Brine concentrate and a portion of the permeate are then pumped through the SeHAWK bioreactor via two Bio Feed pumps. The initial stage (Stage 1) of treatment in the bioreactor consists of upward flow through the 1A and 1B units. Facility representatives stated that at their current influent rate of 0.31 MGD, only Stage 1A was needed for proper treatment. During Stage 1, nutrients are fed into the bioreactor which helps facilitate the biological transformation of nitrate into nitrogen gas, which is then released from the system. In the second stage (Stage 2), the effluent flows back downward through the 2A and 2B units. Stage 2 is where biofiltration occurs in the system, removing selenium and other heavy metals. When the bioreactor is in a backwash cycle, waste from the backwash process is sent to the Waste Sump Tank outside of the bioreactor building, where solids settling occurs. The supernatant water at this stage is pumped out of the tank through an automatic strainer before going through a multimedia filter and a granular activated carbon (GAC) tank. An odor scrubber is also present at this stage of the treatment process. The water is then redirected back to the equalization tank before being reintroduced into the system. Solids that settle in the Waste Sump Tank are taken by McDonald Farms Enterprises to be properly disposed of. Before the waste Page 4 of 12 Inspection Date: June 21, 2022 Town of Milliken Reverse Osmosis Water Treatment Plant (CO0046485) Compliance Evaluation Inspection Report stream enters the bioreactor, there is a bypass option which can be used to route the RO waste directly to the Waste Sump Tank, where it is ultimately pumped to the Little Thompson River. Operators stated that they use this bypass in the event of a bioreactor shut down when the RO units are still in operation. After the effluent goes through both stages of the bioreactor, it is pumped to a Backwash Supply Tank. The water used during bioreactor backwash cycles is stored in this tank. The Backwash Supply Tank is designed to overflow to the bottom of the Reaction Tank, where hydrogen peroxide is injected for the aeration treatment phase. A blower injects air into the Reaction Tank through a series of diffusers at the bottom of the tank. The final effluent sampling takes place before the effluent is discharged from the Facility and into the Town of Milliken's stormwater system. Oxidation-reduction potential (ORP), pH, and Dissolved Oxygen (DO) are measured at this location. As final effluent is transported to the Little Thompson River, it emerges from a PVC pipe into a stormwater culvert collector apron, which is located on the corner of South Quentine Avenue and West Lilac Street, approximately half a mile from the Facility. Operators indicated that this was the last place that the water was uninfluenced by any other source such as stormwater flow from the Town of Milliken before discharging into the Little Thompson River. After this point, the water continues to flow by gravity in the stormwater system about half a mile further north before final discharge into the Little Thompson River. Wastewater Monitoring and Flow During periods of normal operation, CDPS compliance self-monitoring activities and samples are conducted by Milliken ROWTP staff before final effluent leaves the Facility. Compliance sampling takes place after the water leaves the Reaction/Aeration Tank via sampling Port 104 (Outfall 001A), before it is sent to the Little Thompson River through the same manhole that the Facility was pumping untreated well water through on the day of the inspection. Grab samples are collected from one end of Port 104, which is a T-off pipe. On the other end of the pipe, composite samples are taken by a Hach AS950 automatic sampler. Composite samples are flow weighted. Process control samples are also collected by Facility operators. The onsite sample collection location and methods appeared to provide representative samples. The samples are analyzed using both on-site and contract laboratories. Measurements for DO, pH, temperature, conductivity, and ORP are conducted onsite, while weekly analysis for E-Coli and Total Suspended Solids (TSS), monthly analysis for Arsenic (total and potentially dissolved), Bicarbonate, Boron (total), Cadmium (total and potentially dissolved), Calcium (total), Chloride, Chromium Trivalent (total and potentially dissolved), Chromium Hexavalent (dissolved), electrical conductivity, Iron (total and dissolved), Copper (potentially dissolved), Lead (total and potentially dissolved), Manganese (total and potentially dissolved), Magnesium (total), Mercury (total low level), Molybdenum (total), Nickel (total and potentially dissolved), Nitrogen (total inorganic), Selenium (potentially dissolved), Silver (potentially dissolved), Uranium (total), Zinc (potentially dissolved), SAR, Sodium (total), Sulfate, Sulfide, and quarterly analysis for Total Dissolved Solids (TDS), and Total Ammonia, are conducted by Colorado Analytical Laboratories, Inc., the Facility's contract laboratory in Commerce City, Colorado. Whole effluent toxicity (WET) testing is conducted by another contract laboratory, SeaCrest Group in Louisville, Colorado. Facility discharge monitoring reports (DMRs) for 2019 through 2021 were reviewed as a component of this inspection. Since the Facility has been offline since October 2021, DMRs from 2022 were not reviewed. The review included a comparison of reported monitoring results versus requirements and limitations contained within the Permit. Permit limit exceedances were identified and are presented in Section III, Observation No. 1 of this report for additional details. Wastewater Solids Handling Solids generated from the ROWTP are sent to McDonald Farms Enterprises for proper disposal. Page 5 of 12 Inspection Date: June 21, 2022 Town of Milliken Reverse Osmosis Water Treatment Plant (CO0046485) Compliance Evaluation Inspection Report WWTP Operation and Maintenance Management The Permittee currently does not utilize a Computerized Maintenance Management (CMMS) software to track work orders, labor hours, or assets at the Facility. However, the Water/Wastewater Director of the Facility tracks repairs/maintenance in a Microsoft Excel Spreadsheet. The EPA Inspection Team reviewed this spreadsheet as a component of the inspection (refer to Appendix B, Exhibit 1). II. INSPECTION PROCESS Inspection Opening Conference The EPA Inspection Team arrived at the Facility on June 21, 2022, at 9:00 a.m. (MDT) for the inspection. Danny O'Connell of PG Environmental, and Stephanie Meyers of EPA Region VIII displayed their Clean Water Act inspector credentials to Don Stonebrink, the Water/Wastewater Director at the outset of the inspection and explained the purpose of the inspection was to confirm compliance with the Facility's CDPS Permit No. CO0046485 (refer to Appendix C). The EPA Inspection Team informed the Permittee that any information that the Facility deemed to be confidential business information ("CBI") should be identified to EPA representatives during the inspection and it would be handled as CBI according to EPA's CBI procedures. No information provided to the EPA Inspection Team was identified as CBI during the course of the inspection. The list below describes the individuals that participated in the inspection. Inspection Attendee List: EPA Inspectors and Contractors: Stephanie Meyers, US EPA Region 8 Danny O'Connell, PG Environmental (EPA Contractor) Jake Okun, PG Environmental (EPA Contractor) Colorado Department of Public Health (CDPHE) Representatives: Emma Ely, CDPHE Town of Milliken ROWTP Representatives: Don Stonebrink, Town of Milliken Kyle Beyerlein, Town of Milliken Facility Site Walk As part of the inspection process, the EPA Inspection Team visually observed the treatment train and site conditions in the presence of the Water/Wastewater Director and the lead Facility operator. The Facility was completely offline at the time of inspection, but components of the treatment process were still observed. The wastewater process train consists of: RO Membrane System #1 (out of service since the plant was initially brought online) RO Membrane System #2 Equalization Tank Bio Feed Pumps (2) SeHAWK Bioreactor Nutrient Storage Tank and Nutrient Feed Multimedia and GAC Filtration Tanks Sump Waste Tank and Sump Pumps Treated Water Pumps (2) Backwash Supply Tank Page 6 of 12 Inspection Date: June 21, 2022 Town of Milliken Reverse Osmosis Water Treatment Plant (CO0046485) Compliance Evaluation Inspection Report Reaction/Aeration Tank Backwash Pumps (2) Blower Additional equipment and assets that were observed that support the wastewater treatment process include: pH, ORP, DO, and Conductivity Meters Two, 1,100-gallon RO Permeate Storage Tanks H2S Sensor Odor Scrubber Hydrogen Peroxide Storage Automatic Hach Effluent Sampler The Facility site walk began at approximately 11:00 a.m. MDT on June 21, 2022. The walk began in the RO building, where the EPA Inspection Team observed the two RO systems (refer to Appendix A, Photographs 1-2). While the plant was in operation, only RO System #2 had been used due to repeated technical failures with RO System #1 since it was originally installed. The membranes from RO System #1 were not in place at the time of inspection, and an operator log indicated that the membranes had been sold in May 2022 (refer to Appendix A, Photograph 1). The EPA Inspection Team also observed the initial filtration units where RO feed passed through before entering the systems (refer to Appendix A, Photograph 3). Next, Facility representatives showed the two, 1,100-gallon RO permeate storage tanks outside of the RO building (refer to Appendix A, Photograph 4). They stated that the RO permeate was stored here and used for RO membrane CIP and rinses. Waste from the CIP process is drained directly to the sewer system. Concentrate from the RO process is pumped to the equalization tank (refer to Appendix A, Photograph 5). The equalization tank had 16 operational feet, and the tank had approximately eight feet of water in it at the time of the inspection, leaving approximately 50% of the operational volume available. After observing the equalization tank, the EPA Inspection Team observed the two bio feed pumps which pump water from the equalization tank to the SeHAWK bioreactor (refer to Appendix A, Photograph 6). Operators stated that pH and conductivity internal process sampling occur at this location. As water is fed into the bioreactor at this stage, it is injected with a nutrient blend to assist with nitrification. Nutrients, which the operators stated were a proprietary blend, are stored adjacent to the bioreactor in a nutrient storage tank (refer to Appendix A, Photograph 7). Operators stated that the centrifugal nutrient feed pumps had experienced challenges while the bioreactor was in operation, and they had to be modified by the operations team. The nutrient feed pumps were originally fastened to the side of the reactor with adhesive, and this resulted in the nutrient feed pumps not pumping the nutrient blend in the proper amounts. Operators had to unfasten the nutrient feed pumps in order for the system to function properly (refer to Appendix A, Photograph 8). At the time of inspection, new iron plates were being installed in the SeHAWK bioreactor, and the EPA Inspection Team observed the new plates staged next to the bioreactor (refer to Appendix A, Photograph 9). An operator stated that these new plates, along with new seals and gaskets were the latest solution to the repeated structural failures that the bioreactor had experienced since it was brought online in September 2019. Since the bioreactor was being repaired during the inspection, the EPA Inspection Team was able to look at the inner structure of the tank. The bottom plates of the tank were pitted and heavily marked with deep grooves and scratches in the metal (refer to Appendix A, Photograph 10). An operator stated that these marks were a result of normal operation on the system. Facility representatives indicated that once the bioreactor was repaired, only Stage 1A would be used for the initial treatment step. Rather than sending flow through both Stages 1A and 1B before entering Stage 2 treatment, this capacity reduction would help deal with low or variable groundwater flow through the system. According to Facility representatives, it would also allow for Stage 1B to be used for spare parts if needed. Page 7 of 12 Inspection Date: June 21, 2022 Town of Milliken Reverse Osmosis Water Treatment Plant (CO0046485) Compliance Evaluation Inspection Report After observing the SeHAWK bioreactor (refer to Appendix A, Photograph 11), the EPA Inspection Team observed a bypass valve which allows water to be sent directly to the Waste Sump Tank located outside of the bioreactor building rather than being treated in the bioreactor (refer to Appendix A, Photographs 1213). This allows operators to send water directly to the Waste Sump Tank, where it is ultimately pumped to the Little Thompson River, when the bioreactor is offline or under repair. While the bioreactor is operating, water is pumped from the bioreactor and sent to this tank for solids settling during routine backwash cycles. An operator stated that the solids are taken by McDonald Farms Enterprises for proper offsite disposal. They then stated that the supernatant water in this Waste Sump Tank is pumped through an automatic strainer before going through multimedia and GAC filtration (refer to Appendix A, Photograph 14). During the inspection, the EPA Inspection Team observed filter media on the floor around the filtration tanks and Facility representatives stated that they had just recently switched out the filter media. After filtration, the backwash water is then sent back to the equalization tank to be reintroduced to the system. Once water is treated in the bioreactor, water is pumped to the Backwash Supply Tank via two treated water pumps (refer to Appendix A, Photographs 15). The operator said that backwash water was stored in this tank, and that two backwash pumps sent it back through the bioreactor during backwash cycles. When the bioreactor is not backwashing, water flows from the top of the backwash tank downward into the Reaction/Aeration Tank (refer to Appendix A, Photograph 16). Facility representatives showed where hydrogen peroxide is stored/pumped from (refer to Appendix A, Photograph 17), and injected before entering the Reaction/Aeration Tank (refer to Appendix A, Photograph 18). The EPA Inspection Team observed where air from the blowers is injected into the bottom of the Reaction/Aeration Tank (refer to Appendix A, Photograph 19). Once final effluent leaves the Reaction/Aeration Tank, an operator stated that it was sampled for DO, ORP, pH, and conductivity. They showed the EPA Inspection Team the instrumentation panel containing all of the probes for sampling these parameters (refer to Appendix A, Photograph 20), as well as the sampling port where compliance grab sampling for these parameters is conducted for the final treated effluent. The operators internally referred to this as sampling Port 104 (refer to Appendix A, Photograph 21). Facility representatives stated that Port 104 was the same as permitted Outfall 001A, and it was located inside the bioreactor building just off of the Reaction/Aeration Tank. In addition to the grab sample location, Facility representatives showed their Hach AS950 automatic sampler, which is used to take composite compliance samples for Outfall 001A (refer to Appendix A, Photograph 22). Final effluent is then gravity fed into a sump tank, before being pumped toward the Little Thompson River. The EPA Inspection Team observed a manhole outside of the bioreactor building where final effluent would be seen flowing toward the Little Thompson River during normal operation (refer to Appendix A, Photograph 23). Since the Facility was completely offline at the time of the inspection, treated effluent was not being directed to The Little Thompson River during the inspection. However, groundwater was being pumped from the two onsite wells and was observed to be flowing to the Little Thompson River through the Waste Sump Tank (refer to Appendix A, Photograph 23). Facility representatives stated that the Facility was obligated to send a certain amount of water to the Little Thompson River even if the Facility was offline due to water rights with the Town of Milliken. An operator also stated that they were sending approximately 210,000 gallons of water to the river per day while the Facility was offline, and that the water is pumped from the groundwater wells directly through the Waste Sump Tank (refer to Appendix A, Photograph 23), where it is then pumped to the Little Thompson River without treatment. After observing the manhole, Facility representatives, with the EPA Inspection Team, drove approximately half a mile away from the Facility to a point where discharge from the Facility was flowing out of a PVC pipe above the ground surface (refer to Appendix A, Photograph 24) into a stormwater culvert collector apron. The operator stated that this was the last place that their discharge water surfaced before being influenced or comingled with other sources such as the Town of Milliken's stormwater runoff. They stated that no sampling took place at this point, and that they only recently became aware that effluent was coming out of this pipe. This pipe was located at 40.33494 N, 104.86795 W. They expressed that stormwater and other flows were comingling with their discharge at this stage, and that they had no control Page 8 of 12 Inspection Date: June 21, 2022 Town of Milliken Reverse Osmosis Water Treatment Plant (CO0046485) Compliance Evaluation Inspection Report over the stormwater flows that were entering the Little Thompson River from this exposed line. After another half mile drive, the EPA Inspection Team observed the point where final effluent is released from the stormwater system, approximately 25 feet south of the Little Thompson River (refer to Appendix A, Photograph 25), and the confluence point where the final stormwater drainage comingled with treated Facility effluent discharges to the river (refer to Appendix A, Photograph 26). At the time of inspection, the water being pumped from the two groundwater wells was discharging into the Little Thompson River. The groundwater well discharge was observed at the exposed PVC pipe (refer to Appendix A, Photograph 24), and was clear and free of foams, solids, or odors. A Facility Process Flow Diagram is included for reference in Appendix B, Exhibit 2. Records Review The EPA Inspection Team conducted a records review to evaluate the Permittee's compliance with the Permit. Some of the records and reports required by the Permit were available for review prior to and after the inspection. Bioreactor standard operating procedures (SOPs), operator logs, the most recent Permit application, process flow diagrams, and calibration records were reviewed offsite. The Plant's discharge monitoring reports (DMRs) were obtained electronically and reviewed offsite after the onsite inspection. The following records were requested and reviewed: DMR data during the period from September 1, 2019, through May 31, 2022 Contract lab reports (September 2019 through May 2022, during months of discharge) Monthly Operations Reports (September 2019 through May 2022) Onsite laboratory bench sheet and process control data (September 2019 through May 2022) Compliance Order of Consent MC-160803-1 Progress Reports (2019-2021) Daily rounds sheets DMR QA Study Results WET Test Results (2020) Contract Lab Certification SOPs (bioreactor) WWTF flow diagram III. SUMMARY OF OBSERVATIONS The following section summarizes the EPA Inspection Team's observations relative to the Permit requirements, including the status of certain treatment units, operation and maintenance practices, and the Permittee's monitoring and reporting documentation. Part I.A.2, Limitations, Monitoring Frequencies and Sample Types, of the Permit, identifies effluent limitations, monitoring frequencies and sample type requirements for Outfall 001A discharges. As part of the data review, the EPA Inspection Team reviewed EPA's Integrated Compliance Information System (ICIS) database and monthly DMRs to compare reported values against effluent limitations defined in the Permit (refer to Appendix B, Exhibit 3) as well as EPA's Enforcement and Compliance History Online (ECHO) database (refer to Appendix B, Exhibit 4) in order to evaluate the Permittee's compliance with effluent limitations identified in the Permit. The EPA Inspection Team observed that the Permittee experienced 8 effluent limitation exceedances during the period of review (2019-2022). Documented in EPA's ICIS database and monthly DMRs provided by the Permittee are the Facility's 8 effluent limit exceedances for Outfall 001A, experienced between March 1, 2019, and March 31, 2022 (refer to Appendix B, Exhibit 3, and Table 1 below). The ECHO database indicates the Facility was in a state of significant noncompliance (SNC) from October 1, 2019, through Page 9 of 12 Inspection Date: June 21, 2022 Town of Milliken Reverse Osmosis Water Treatment Plant (CO0046485) Compliance Evaluation Inspection Report March 31, 2022, with additional violations noted for the period of April 1, 2022, through June 24, 2022 (refer to Appendix B, Exhibit 4). Table 1. Outfall 001A Final Effluent Exceedances (March 1, 2019, through March 31, 2022) Permit # Monitoring Period End Date Parameter Name DMR Permit Value Limit Units Limit Type CO0046485 CO0046485 CO0046485 CO0046485 CO0046485 CO0046485 CO0046485 CO0046485 09/30/2019 12/31/2019 03/31/2020 01/31/2021 08/31/2021 10/31/2021 10/31/2021 10/31/2021 Mercury, total [as Hg] Static Renewal 7 Day Chronic Ceriodaphnia dubia Static Renewal 7 Day Chronic Ceriodaphnia dubia Sulfide-hydrogen sulfide [undissociated] Arsenic, total recoverable Arsenic, total recoverable Selenium, potentially dissolved Selenium, potentially dissolved < .2 .05 7.7 18 11.5 18 .38 .31 1.8 1.2 1.8 1.2 18.3 12.3 18.3 18 ug/L tox chronic tox chronic mg/L ug/L ug/L ug/L ug/L 30-Day Average Minimum Value Minimum Value 30-Day Average 30-Day Average 30-Day Average 30-Day Average Daily Max Between September 2019 and October 2021 (26 months), the Facility was not in operation for 5 months due to bioreactor shutdowns and repair (refer to Appendix B, Exhibit 5). During the 21 other months that the Facility was operational, they experienced 6 effluent limit violations, and two failed WET tests. However, when considering the effluent limits that will become effective November 1, 2023, using the reported effluent values across those 21 operational months, the Facility would experience effluent exceedances for Arsenic, H2S, and E. Coli almost every single month, and exceedances for Selenium for several months. Facility representatives stated that even if the bioreactor was repaired structurally, they would still have difficulty meeting the new effluent limits that will be set in place starting November 1, 2023, as they already had difficulty meeting the less stringent limits that were already in place (refer to Appendix B, Exhibit 5). At the time of the inspection, the EPA Inspection Team observed that the Facility had experienced numerous Permit effluent limit violations and was in significant noncompliance. Facility representatives indicated that many of the parameter exceedances and some of the failures in their treatment train are a result of variable groundwater flow rates in the system, particularly during off-peak season (winter). They stated that it is difficult to produce enough treated water, which in turn generates the appropriate wastewater flow to operate their Facility properly during the wintertime, and that switching to seasonal operation was being considered for the next Permit term. According to Facility representatives, one of the primary challenges associated with this plan is the amount of time that it takes to flush the system of "dirty water" to get back into compliance after the system has been sitting for several months. One Facility representative stated that it can take 3-4 weeks of normal process operations during a start-up before they are able to get back into compliance with their permitted effluent limits. Part I.B.1, Facilities Operation and Maintenance, of the Permit states, "The permittee shall at all times properly operate and maintain all facilities and systems of treatment and control (and related appurtenances) which are installed or used by the permittee as necessary to achieve compliance with the conditions of this permit." Page 10 of 12 Inspection Date: June 21, 2022 Town of Milliken Reverse Osmosis Water Treatment Plant (CO0046485) Compliance Evaluation Inspection Report According to Facility representatives, a series of structural failures in the SeHAWK bioreactor caused the Facility to be completely offline at the time of the inspection (refer to Appendix B, Exhibit 1). The seal between the metal drain plates and the bottom of the bioreactor failed during operation and had to be taken offline in October 2021. Before that, other structural failures had caused the bioreactor to be taken offline in June 2020 and January 2021. At the time of inspection, new plates were being installed in the bioreactor with upgraded seals, gaskets, and additional angle iron supports (refer to Appendix A, Photograph 9). The Facility representatives informed the EPA Inspection Team that these improvements would ideally fix the structural failures pertaining to the bioreactor. They indicated that the bioreactor rehab should be complete approximately 3-4 weeks from the time of the inspection. At the time of the inspection, the EPA Inspection Team observed severe structural pitting that was taking place in the metal insides of the bioreactor. Facility representatives stated that this was a result of normal operational wear and tear (refer to Appendix A, Photograph 10). At the time of inspection, Facility representatives stated that they don't currently track all of their assets, and that they were working towards that to eventually help with maintenance schedules. The Permittee currently does not utilize a CMMS software to track work orders, labor hours, or assets at the Facility. The Facility representatives stated that they use Microsoft Excel to track corrective and preventative maintenance done on select assets at the Facility (refer to Appendix B, Exhibit 1). Part I.D.5.a, Records, of the Permit states, "The permittee shall establish and maintain records. Those records shall include, but not be limited to, the following: i. The date, type, exact place, and time of sampling or measurements; ii. The individual(s) who performed the sampling or measurements; iii. The date(s) the analyses were performed; iv. The individual(s) who performed the analysis; v. The analytical techniques or methods used; and vi. The results of such analysis. vii. Any other observations which may result in an impact on the quality of the discharge as indicated in 40 CFR 122.44 (i)(1)(iii)." During the records review portion of the inspection, the EPA Inspection Team noticed that white-out had been used to cover up past entries on daily lab worksheets, and new values had been written over it. The daily lab worksheets were being used to track internal process sampling, and thus the white-out was not being used to cover up compliance sampling values. This completely masked the old entries, and it was unknown why the values were changed by the Permittee (refer to Appendix B, Exhibit 6). It is recommended that corrected values have a one-line strike through, with the initials and date of who made the correction and comments as to why the correction was made. Part II.A.2, Change in Discharge, of the Permit states, "The permittee shall give advance notice to the Division, in writing, of any planned physical alterations or additions to the permitted facility. Notice is required only when: a. The alteration or addition could significantly change the nature or increase the quantity of pollutants discharged..." At the time of the inspection, the Facility was pumping untreated water from the two onsite groundwater wells directly into the Waste Sump Tank before being pumped Page 11 of 12 Inspection Date: June 21, 2022 Town of Milliken Reverse Osmosis Water Treatment Plant (CO0046485) Compliance Evaluation Inspection Report directly to the Little Thompson River without any treatment (refer to Appendix A, Photographs 23 and 24). Facility representatives stated that this was normal procedure during plant shutdowns because they had to meet certain water rights limits (i.e., augmentation) set by the Town of Milliken. A Facility representative stated that they were sending 210,000 gallons of untreated well water a day to the Little Thompson River at the time of the inspection. This untreated groundwater discharge, observed at the time of inspection, was not described, or covered under the Facility's CDPS Permit (refer to Appendix C) or the Facility's Fact Sheet. IV. CLOSING CONFERENCE At approximately 12:50 p.m. (MDT) on June 21, 2022, the EPA Inspection Team met with the Facility representatives for a closing conference and shared preliminary observations. The EPA Inspection Team reiterated that all preliminary observations discussed were not formal compliance determinations. Any preliminary observations shared were subject to further investigation by the EPA Inspection Team upon the additional review of records and documentation. Additional observations may be contained in this inspection report that were not identified at the time of the closing conference. The inspection concluded on June 21, 2022, at approximately 1:00 p.m. (MDT). 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