Document 50aBRzEZ8EewNNKeLXpdB3YRz

Pretreatment Audit Report Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 Cheyenne, Wyoming March 10, 2025 to March 13, 2025 Prepared by: Al Garcia, Pretreatment Coordinator U.S. Environmental Protection Agency, Region 8 Wastewater Section (8WD-CWW) 1595 Wynkoop Denver, CO 80202 303.312.6382 garcia.al@epa.gov 1 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Report Review and Signature Drafter Name Al Garcia Reviewer Name Althea Wilson Supervisor Signature/Name MICHAEL BOEGLIN Digitally signed by MICHAEL BOEGLIN Date: 2025.04.29 10:39:33 -06'00' Michael Boeglin Address/Phone Number U.S. EPA Region 8 1595 Wynkoop Street 8WD-CWW Denver, Colorado 80202 303-312-6382 Address/Phone Number U.S. EPA Region 8 1595 Wynkoop Street 8ENF-W-NP Denver, Colorado 80202 303-312.6026 Address/Phone Number U.S. EPA Region 8 1595 Wynkoop Street 8WD-CWW Denver, Colorado 80202 303-312-6250 Date 04/10/2025 Date 04/17/2025 Date 04/29/2025 2 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Pretreatment Audit Summary Table Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025 to March 13, 2025 Pretreatment Audit Findings Pretreatment Requirement and Corrective Action Section 7.0 - Industrial User Inventory and Characterization 1. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(i-iii) states, "The POTW shall develop and implement procedures to ensure compliance with the requirements of a Pretreatment Program. At a minimum, these procedures shall enable the POTW to: Identify and locate all possible Industrial Users which might be subject to the POTW Pretreatment Program. Any compilation, index or inventory of Industrial Users made under this paragraph shall be made available to the Regional Administrator or Director Pretreatment Requirements 40 C.F.R. 403.8(f)(2)(ii) upon request." This requires a POTW to Corrective Action Item develop and maintain an inventory of industrial users (IUs) in their service area. Conduct a facility inspection at Eagle Claw Manufacturing to gather information on the "Identify the character and volume of processes conducted at the facility as a follow pollutants contributed to the POTW by the up to the facility's submitted IU survey. In Industrial Users identified under paragraph addition, the BOPU needs to either send a (f)(2)(i) of this section. This information shall survey to Koontz Tooling or conduct a facility be made available to the Regional inspection to maintain its current industrial Administrator or Director upon request." This inventory. requires a POTW to characterize the IUs in Submit the results of the IU inventory follow- the inventory of their service area. up activities and characterization for Eagle "Notify Industrial Users identified under Claw Manufacturing and Koontz Tooling to paragraph (f)(2)(i) of this section, of the EPA. applicable Pretreatment Standards and any applicable requirements under sections 204(b) and 405 of the Act and subtitles C and D of the Resource Conservation and Recovery Act. Within 30 days of approval pursuant to 40 C.F.R. 403.8(f)(6), of a list of significant industrial users, notify each significant industrial user of its status as such and of all requirements applicable to it as a result of such status." These procedures must 3 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 include the notification of IUs of applicable Pretreatment Standards and other applicable requirements. The BOPU provided its current IU inventory of the IUs in its service area for the EPA to review. Based on the EPA's review, the BOPU's IU inventory contains about 1,500 IUs and appears to be current and representative of the POTW's service area. It also appears that the BOPU is devoting resources to continually maintain the inventory and capture current conditions of IUs in its service area. Based on the EPA's review of these IU Pretreatment records, it appears that two IUs do not contain adequate information or data to characterize the pollutants and loadings, as required in 40 C.F.R. 403.8(f)(2)(ii). The BOPU needs to conduct a facility inspection at Eagle Claw Manufacturing to gather information on the processes conducted at the facility, as a follow up to the facility's submitted IU survey. In addition, the BOPU needs to either send a survey to Koontz Tooling or conduct a facility inspection to maintain the industrial user inventory. Section 8.0 -Evaluation of Pretreatment Records and Permit Specific Issues Pretreatment Records 2. The Pretreatment Regulations at 40 C.F.R. Pretreatment Requirements 403.8(f)(2)(ii) require the BOPU to "Identify the 40 C.F.R. 403.8(f)(2)(ii) character and volume of pollutants contributed to the POTW." The 2023 and 2024 inspection reports Corrective Action Item include brief descriptions of the manufacturing processes and should include more detail regarding the facility's chemical storage/handling/transfer, process/unit operations, wastestream generation from these unit operations, wastestream management or wastewater treatment, sampling Provide more detail in the SIU inspection reports to capture current conditions at the facility and to identify the character and volume of contributed pollutants. Recommendation procedures to provide a current characterization, The EPA recommends the BOPU take digital including an evaluation of slug discharge potential photos during facility inspections and ensure and process or treatment plant changes. This these photos capture areas relevant to the information is important for capturing current Pretreatment permit. These areas can include conditions and determining if control mechanisms but are not limited to floor drains, unit are needed. These could include an SIU permit, operations, raw material/chemical storage, BMPs, modifications to existing control applicable chemical handling equipment, mechanisms, or control plans such as slug discharge wastestreams, wastewater treatment, and control plans or spill plans. discharge locations/monitoring points. 4 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 During the audit, the EPA provided compliance assistance and training on conducting facility inspections. This included training on gathering data/information, generating inspection reports that provide current facility conditions that may impact categorical determinations, permit conditions, and control documents such as the slug discharge control plan or toxic organic management plans. The BOPU provides a follow up letter after an inspection to implement the Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(iii) that require the BOPU to "Notify Industrial Users identified under paragraph (f)(2)(i) of this section, of applicable Pretreatment Standards...". The EPA recommends the BOPU include a statement that the IU is responsible to notify the BOPU if process changes occur that may change the evaluation. 3. The Pretreatment Regulations at 40 C.F.R. Pretreatment Requirements 403.12(o) establish the maintenance and recordkeeping requirements for the Pretreatment 40 CFR 403.12(o) records. Corrective Action Item Based on the EPA's review of the BOPU's recordkeeping, it appears that the BOPU needs to improve its recordkeeping and ensure the reports are adequately evaluated and filed in a timely manner. Evaluate current report file management procedures and ensure that reports are adequately evaluated and filed in a timely manner. Black Hills Energy 4. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(ii) require the BOPU to "Identify the character and volume of pollutants contributed to the POTW." The EPA evaluated the 2023 and 2024 facility inspection reports the BOPU conducted at Black Hills Energy. The 2024 Black Hills Energy inspection report only includes a brief descriptions of the steam electric process, oil/water separator, and sludge disposal method but is missing flow information. The inspection report should contain information regarding the generation of wastewater from the steam electric turbines and water supply treatment. If applicable, the report should include a description of the boiler cleaning and the management of PCB disposal. In addition, the inspection report should adequately describe the cooling tower management including chemical usage and discharge from the cooling towers to ensure the sampling/monitoring is representative. Pretreatment Requirements 40 C.F.R. 403.8(f)(2)(ii) Corrective Action Item Ensure the Black Hills Energy inspection reports are complete and contain adequate information to characterize current conditions at the facility. In addition, the 2024 Black Hills Energy inspection report appears incomplete. The report is missing flow data information, information to determine if the SIU's sampling facilities are in satisfactory 5 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 condition and a clear determination of proper sludge management and records reviewed. The 2024 inspection report does not contain a signature or date. 5. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(iii)(B)(3) state that a permit must be enforceable and contain the following elements: "Effluent limits, including Best Management Practices, based on applicable general Pretreatment Standards in part 403 of this chapter, categorical Pretreatment Standards, local limits, and State and local law." Part I, section A.3 of the Black Hills Energy permit Pretreatment Requirements contains the applicable limits for cooling tower 40 C.F.R. 403.8(f)(1)(iii)(B)(3) blowdown for Chromium and Zinc at outfall 001. However, the permit does not include the 126 priority pollutants contained in chemicals added for 40 C.F.R. 423.17(a)(4)(i) 40 C.F.R. 423.17(a)(4)(ii) cooling tower maintenance required at 40 C.F.R. 40 C.F.R. 423.17(b)(1) 423.17(a)(4)(i). The Steam Electric Pretreatment Standards for New Sources (PSNS) at 40 C.F.R. Corrective Action Item 423.17(a)(4)(ii), as an option, allow the facility to Include all applicable PSNS limits and demonstrate by engineering calculations that the prohibitions found in the Steam Electric Point regulated pollutants are not detectable in the final Source Category: discharge by the analytical methods in 40 CFR part 136, instead of the monitoring in compliance with the standards for the 126 priority pollutants may. PCB discharge prohibition 126 priority pollutants contained in chemicals added for cooling tower The Steam Electric Point Source Categorical maintenance. Pretreatment Standards for New Sources (PSNS) at 40 C.F.R. 423.17(b)(1) state that "There shall be no discharge of polychlorinated biphenyl compounds such as those used for transformer fluid." The Black Hills Energy permit does not include this PCB discharge prohibition. The BOPU Require the facility to eliminate the introduction of RO reject wastewater to outfall 001 or modify the permit to calculate limits based on the combined wastestream formula to account for the RO dilution wastestream. is required to modify the current Black Hills Energy Evaluate the 100% BOD and TSS loading permit to include this PSNS. allocations to Black Hills as this restricts the Part I, section A.1 of the Black Hills Energy permit allows reverse osmosis (RO) reject water (nonregulated wastewater) to be introduced into outfall BOPU from allocating BOD and TSS loadings to other SIUs discharging to the Dry Creek POTW. 001. The outfall 001 is the monitoring point for regulated cooling tower blowdown, so the introduction of RO reject water is creating a dilution wastestream. The BOPU established local limit loadings for BOD at 9,788 lbs/day and TSS at 19,447 lbs/day for all SIU discharges to the Dry Creek POTW. The BOPU 6 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 has allocated the 100% of the BOD and TSS local limits loading to Black Hills Energy in its permit. 6. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(iii)(B)(4) state that a permit must be enforceable and contain the following elements: "Self-monitoring, sampling, reporting, notification and recordkeeping requirements, sampling location, sampling frequency, and sample type, based on the applicable general Pretreatment Standards, categorical Pretreatment Standards, local limits, and Pretreatment Requirements State and local law." The Pretreatment Regulations at 40 C.F.R. 403.12(h) state that the Control 40 C.F.R. 403.8(f)(1)(iii)(B)(4) Authority must require appropriate reporting from those Industrial Users with discharges that are not subject to categorical Pretreatment Standards. 40 C.F.R. 403.12(h) Corrective Action Item Significant Non-categorical Industrial Users must Modify the Black Hills Energy permit to submit to the Control Authority at least once every six months a description of the nature, concentration, and flow of the pollutants required to be reported by the Control Authority. These reports must be based require at a minimum, semi-annual sampling at outfall 003 for all permit-limited pollutants of concern. on sampling and analysis performed in the period covered by the report, and in accordance with the techniques described in 40 CFR part 136. Part II, section A.3 of the Black Hills Energy permit only requires annual sampling for Pb, Ni, Ag, TPH and BTEX at outfall 003. Cheyenne Renewable Diesel Company (CRDC) 7. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(iii)(B)(3) state that a permit must be enforceable and contain the following elements: "Effluent limits, including Best Management Pretreatment Requirements Practices, based on applicable general Pretreatment 40 C.F.R. 403.8(f)(1)(iii)(B)(3) Standards in part 403 of this chapter, categorical Pretreatment Standards, local limits, and State and Corrective Action Item local law." Evaluate the 100% BOD and TSS allocation The BOPU established local limit loadings for BOD at 4,845 lbs/day and TSS at 3,071 lbs/day for all SIU discharges to the Crow Creek POTW. The BOPU to CRDC as this restricts the BOPU from allocating BOD and TSS loadings to other SIUs discharging to the Crow Creek POTW. has allocated 100% of the BOD and TSS local limits loading to CRDC in its permit. Walmart Distribution Center 7 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 8. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(iii)(B)(4) state that a permit must be enforceable and contain the following elements: "Self-monitoring, sampling, reporting, notification and recordkeeping requirements, sampling location, sampling frequency, and sample type, based on the applicable general Pretreatment Standards, categorical Pretreatment Standards, local limits, and Pretreatment Requirements State and local law. Further, the Pretreatment Regulations at 40 C.F.R. 403.12(g)(3) state that the 40 C.F.R. 403.8(f)(1)(iii)(B)(4) required reports must be based upon data obtained Corrective Action Item through appropriate sampling and analysis performed during the period covered by the report. which data are representative of conditions occurring during the reporting period. Evaluate the sample type for mercury to ensure the sample type is representative of discharges for the production day. The BOPU requires sampling for permit-limited metals to be conducted as a 24-hour composite, except for mercury which is sampled as a grab sample. The EPA is not aware why mercury is required as a grab sample instead of a 24-hour composite similar to other permit-limited metals. 9. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(iv)(B) require the BOPU to "Require the submission of all notices and self-monitoring reports from Industrial Users as are necessary to assess and Pretreatment Requirements assure compliance by Industrial Users with 40 C.F.R. 403.8(f)(2)(vii) Pretreatment Standards and Requirements, including but not limited to the reports required in 403.12." Corrective Action Item Based on the EPA's review of the Pretreatment records, the 1st Quarter 2024 self-monitoring compliance report due on April 30, 2024 was not date stamped as received by the BOPU. As a result, Ensure that the reports and notifications received are consistently date stamped to determine compliance with the permitrequired due dates. the EPA was unable to determine if the report was received by the due date listed in the permit. Dystar Foam Control 10. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(ii) require the BOPU to "Identify the character and volume of pollutants contributed to the POTW." The EPA evaluated the 2023 and 2024 facility inspection reports from the inspections the BOPU conducted at Dystar Foam Control. The 2024 inspection report only includes brief descriptions of Pretreatment Requirements 40 C.F.R. 403.8(f)(2)(ii) Corrective Action Item Ensure the Dystar inspection report is complete and contains adequate information to 8 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 the defoamer manufacturing, raw materials and wastestream management. The inspection report should contain information regarding the raw materials receipt at the outside tank farm and in the warehouse, including handling and transfer to the blending tanks. In addition, the inspection report should contain information regarding wastestream generation and management. characterize the facility, based on current conditions. 11. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(v) require the BOPU to "Carry out all inspection, surveillance and monitoring procedures necessary to determine, independent of information supplied by Industrial Users, compliance or noncompliance with applicable Pretreatment Standards and Requirements by Industrial Users." The EPA conducted an oversight facility inspection at Dystar Foam Control on January 28, 2025, as part of the Pretreatment audit of the BOPU. The inspection report was submitted to the facility on March 12, 2025. The inspection report and cover letter were submitted to the facility on March 27, 2025, and are enclosed with this audit report. Based on observations from the facility inspection, the EPA observed a constructed trench drain in the Cold Storage Room. The trench drain is not equipped with a pump to convey spills or leaks to the wastewater storage tank and is only used for containment of potential spills. The facility stated during the inspection that the room is not used for liquid storage. Based on observations from the facility inspection, an open floor drain leading to the BOPU's sanitary sewer exists within the retaining wall of tank #17 located in the warehouse. Although the tank is not used according to facility representatives, the open floor drain represents a potential slug discharge to the BOPU in case of inadequate training or operator error when managing spills occurring in the warehouse. This may result in a violation of the facility's zero-discharge permit. Pretreatment Requirements 40 C.F.R. 403.8(f)(1)(v) Corrective Action Item The EPA recommends the SIU develop a slug discharge control plan to ensure the proper management of spills that may occur from the large volume of liquid stored in the warehouse and cold storage room. The EPA further recommends the facility permanently plug the open floor drain within the retaining wall of tank #17 to eliminate any potential slug discharge potential. Section 10.0 - Control Authority Compliance Monitoring 12. As required in 40 C.F.R. 403.8(f)(2), the POTW Pretreatment Requirements shall "develop and implement procedures to ensure 9 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 compliance with the requirements of a Pretreatment Program." The development and implementation of a sampling plan or procedures ensures the POTW is appropriately and consistently performing sampling or monitoring events, as well as providing enforceable data that is representative of the discharge conditions at the facility. The sampling plan should include the following: Purpose and objective of the sampling program, Specific sampling protocols at each facility sampling location to ensure representative sampling, and Appropriate QA/QC procedures to ensure legally defensible data. In addition, the Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(vii) require the BOPU to ensure "Sample taking and analysis and the collection of other information shall be performed with sufficient care to produce evidence admissible in enforcement proceedings or in judicial actions." The BOPU has developed a general overview of sampling in its IPP Guidance that includes an overview of operation, use and maintenance of automatic samplers. In addition, the BOPU has developed annual compliance sampling that provides an overview of compliance sampling procedures in its IPP Guidance and sampling guides for each SIU. The BOPU needs to incorporate QA/QC procedures such as equipment blanks, trip blanks, sample duplicates, matrix spikes, and control standards to ensure the sampling and analytical techniques are in control and compliance with 40 CFR 136. The EPA recommends the BOPU consolidate its SIU sampling procedures in SIU-specific sampling protocols to ensure consistent sampling that is representative for the production day. In addition, the EPA recommends the BOPU incorporate digital photos into the SIU-specific sampling protocols. 40 C.F.R. 403.8(f)(2) 40 C.F.R. 403.8(f)(2)(vii) Corrective Action Item Update the SIU-specific protocols to include appropriate QA/QC (such as equipment blanks, trip blanks, sample duplicates, matrix spikes, and control standards), to ensure the sampling and analytical techniques are in control and comply with 40 C.F.R. 136. Recommended The EPA recommends the BOPU consolidate its SIU sampling procedures in SIU-specific sampling protocols to ensure consistent sampling that is representative for the production day. The EPA recommends the BOPU incorporate digital photos in the SIUspecific sampling protocols. Section 13.3 - Best Management Practices - Dental Amalgam Rule 13. The Dental Amalgam Rule, found in 40 C.F.R. Part 441, was promulgated as a final rule with new source dental facilities required to be in compliance with the Pretreatment Requirements 40 C.F.R. 441.50 10 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Pretreatment Standards as of July 14, 2017, and existing source dental facilities required to be in compliance as of June 14, 2020. Compliance with the rule requires the installation of an ISO1143 amalgam separator or equivalent device, and compliance with the following two BMPs: Prohibition on the use of oxidizing or chlorinecontaining line cleaners; and Ensuring all amalgam process wastewater including chair-side traps, screens, vacuum pump filters, dental tools, cuspidors or collection devices are treated through the amalgam separator. In addition, the new and existing dental facilities are required in 40 C.F.R. 441.50 of the Dental Amalgam Rule to provide a report that characterizes the dental facility and certifies compliance. The new source dental facilities are required to be in compliance upon discharge and submit a one-time compliance report within 90 days of startup. The BOPU has identified 43 dental facilities in its service area and has received one-time compliance reports within the deadline required by the Rule. The EPA reviewed the one-time compliance reports to ensure compliance with the reporting requirements of the Dental Amalgam Rule in 40 C.F.R. 441.50. The following compliance reports are not complete. The BOPU is required to follow up with the following dental offices to ensure the dental facilities comply with the Dental Amalgam Rule: (Note: most reports are not date stamped by the BOPU): The Smile Academy (Children's Dentistry) Dana Barnes Jerri Donahue Gentle Touch Kincheloe and Tonso Mark D Rinne Corrective Action Item Follow up with the identified dental offices to ensure these dental facilities comply with the Dental Amalgam Rule. 11 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Table of Contents 1.0 Introduction............................................................................................................ 16 2.0 Publicly Owned Treatment Works (POTW) Information ..................................... 17 2.1 NPDES Permit.................................................................................................... 19 3.0 Resources ............................................................................................................... 26 3.1 Resources Regulatory Background .................................................................... 26 3.2 Evaluation of the BOPU`s Resources and Funding ........................................... 26 3.3 Examples of Available Pretreatment Training/Resources ................................. 27 4.0 Municipal Ordinance and Intergovernmental Agreements.................................... 27 4.1 Legal Authority Background.............................................................................. 27 4.2 BOPU Municipal Ordinance .............................................................................. 29 4.3 Inter-Jurisdictional or Governmental Agreements (IGA) .................................. 29 4.3.1 IGA Regulatory Background ...................................................................... 29 4.3.2 Evaluation of the BOPU `s IGA with Outside Contributing Jurisdictions . 30 5.0 Local Limits ........................................................................................................... 30 5.1 Local Limits Regulatory Background ................................................................ 30 5.2 Local Limits Requirements Established in the BOPU `s NPDES Permits ........ 32 5.3 The EPA Evaluation of the BOPU `s Local Limits ........................................... 32 5.3.1 Technically based Local Limits .................................................................. 32 5.3.2 Other Numeric Limits ................................................................................. 33 5.3.3 Dilution Prohibition .................................................................................... 34 5.4 Local Limits Technical Evaluation-Regulatory Background............................. 34 5.5 Technical Evaluation of the BOPU `s Local Limits .......................................... 35 5.6 Permit or Site-Specific Limits............................................................................ 36 6.0 Pretreatment Operating Procedures ....................................................................... 37 6.1 Regulatory Background...................................................................................... 37 6.2 Standard Operating Procedures (SOPs) ............................................................. 38 6.3 Templates ........................................................................................................... 38 6.4 Records and Data Management.......................................................................... 38 6.4.1 Regulatory Background .............................................................................. 38 6.4.2 Recordkeeping and Data Management ....................................................... 39 12 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 6.5 Receipt of Discharge Monitoring Reports and Notifications............................. 40 6.6 Management of Confidential Records................................................................ 40 7.0 Industrial User Inventory and Characterization..................................................... 41 7.1 Regulatory Background...................................................................................... 41 7.2 Industrial User Identification and Characterization Procedure .......................... 42 7.3 Industrial User Database of the BOPU `s Service Area..................................... 43 8.0 Evaluation of Pretreatment Records and Permit Specific Issues ........................... 43 8.1 Regulatory Background...................................................................................... 43 8.2 The EPA's Evaluation of the BOPU `s Permitting Legal Authority.................. 46 8.3 Permit Template Overview ................................................................................ 46 8.4 Specific Permit Record Findings ....................................................................... 46 8.4.1 Permit records Overview ............................................................................ 46 8.4.2 Black Hills Energy ...................................................................................... 48 8.4.3 Cheyenne Renewable Diesel Company (CRDC) ....................................... 50 8.4.4 Walmart Distribution Center....................................................................... 50 9.0 Significant Industrial User Facility Inspections..................................................... 52 9.1 Regulatory Background...................................................................................... 52 9.2 Right of Entry..................................................................................................... 52 9.3 Facility Inspection Records - Background ........................................................ 53 9.4 Evaluation of the BOPU `s Inspection Reports/Records ................................... 55 9.5 Notification of Applicable Pretreatment Standards ........................................... 55 9.6 Facility Inspections ............................................................................................ 55 10.0 Control Authority Compliance Monitoring ........................................................... 55 10.1 Regulatory Background .................................................................................. 55 10.2 Sampling Plan and Protocols .......................................................................... 56 10.2.1 Site-Specific Sampling Protocols ............................................................... 56 10.2.2 Quality Assurance/Quality Control (QA/QC) ............................................ 57 10.3 The EPA Evaluation of the BOPU `s Control Authority Monitoring ............ 57 10.3.1 SOPs............................................................................................................ 57 10.3.2 BOPU `s Control Authority Monitoring ..................................................... 58 11.0 Enforcement........................................................................................................... 58 13 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 11.1 Regulatory Background .................................................................................. 58 11.2 Enforcement Legal Authority ......................................................................... 59 11.3 Enforcement Response Plan (ERP) ................................................................ 59 11.4 Compliance Evaluation................................................................................... 59 11.5 SNC Calculations and Public Participation .................................................... 59 12.0 Trucked and Hauled Waste.................................................................................... 60 12.1 Regulatory Background .................................................................................. 60 12.2 Legal Authority............................................................................................... 61 12.3 Trucked and Hauled Waste Disposal Location and Control Mechanisms ..... 62 12.3.1 Crow Creek POTW..................................................................................... 62 12.3.2 Dry Creek POTW ....................................................................................... 62 12.3.3 RV Disposal Stations .................................................................................. 64 13.0 Best Management Practices - Sector Control Programs ....................................... 64 13.1 Regulatory Background .................................................................................. 64 13.2 Authority in Rules and Regulations................................................................ 65 13.3 Dental Amalgam BMP Sector Control Program ............................................ 65 13.4 FOG Sector Control Program ......................................................................... 66 14.0 PFAS Roadmap and Implementation .................................................................... 66 14.1 2021 EPA PFAS Strategic Roadmap.............................................................. 66 14.2 Leverage NPDES permitting to reduce PFAS discharges to waterways........ 67 14.3 Impact of the NPDES Initiatives on the BOPU `s Pretreatment Program...... 68 Figures Figure 1 - Crow Creek POTW Service Area.................................................................... 20 Figure 2 - Crow Creek POTW Process Diagram ............................................................. 21 Figure 3 - Crow Creek POTW - Google Maps View....................................................... 22 Figure 4 - Dry Creek POTW Service Area ...................................................................... 23 Figure 5 - Dry Creek POTW Process Diagram................................................................ 24 Figure 6 - Dry Creek POTW - Google Maps View......................................................... 25 Figure 7 - Dry Creek POTW Septic Disposal Station...................................................... 63 Figure 8 - Dry Creek POTW Septic Disposal Station Sign ............................................. 63 Figure 9 - Dry Creek POTW Septic Disposal Station - Septic Truck Discharge ............ 64 14 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Tables Table 1 - Local Limits for the Dry Creek POTW Service Area ...................................... 32 Table 2 - Local Limits for the Crow Creek POTW Service Area.................................... 33 15 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 1.0 Introduction The U.S. Environmental Protection Agency, Region 8 (EPA) conducted an audit of the Pretreatment program, administered by the Cheyenne Board of Public Utilities, WY (BOPU) from March 10, 2025 to March 13, 2025. The Pretreatment audit started on March 10, 2025 at 9:45 a.m. with an opening interview. The closing conference was held on March 13, 2025 at 7:30 a.m. during which the EPA presented the preliminary observations, conclusions, and findings from the audit. Participants in the audit included: Cheyenne Board of Public Utilities Vicki Dowdy Nathaniel Kaufhold Jake Ward Rob Achenbach Matt Buelow Brad Brooks Compliance Supervisor, vdowdy@cheyennebopu.org Pretreatment Coordinator, nkaufhold@ cheyennebopu.org Pretreatment Specialist, jward@ cheyennebopu.org Pretreatment Specialist, rachenbach@ cheyennebopu.org Division Manager, mbuelow@ cheyennebopu.org Director (Opening Interview) bbrooks@ cheyennebopu.org EPA Al Garcia Region 8 Pretreatment Coordinator The primary purpose of the EPA audit was to evaluate the Pretreatment program administered and implemented by the BOPU. In addition, the audit served as a forum for the EPA and the BOPU to discuss issues related to the implementation of the Pretreatment program, including PFAS requirements in the BOPU's NPDES permit, and for the EPA to provide outreach and training to the BOPU. The EPA Pretreatment audit consisted of an evaluation of the following: The BOPU's legal authority codified in Title 13 - Public Services, Chapter 13.20 - Wastewater Treatment and Disposal of the municipal ordinance. Development and implementation of the BOPU's local limits. The BOPU's resources to implement the Pretreatment program in its service area. Implementation policies and templates developed by the BOPU. Review and evaluation of the Pretreatment programmatic activities and records maintained for the permitted Significant Industrial Users (SIUs). Site inspection of selected SIUs and Industrial Users (IUs) in the service area to ensure the Pretreatment records reflect current conditions at the facilities. Discussion of the Pretreatment Regulations and implementation. The following sections of the report highlight the findings, corrective actions, and recommended actions of the audit. The action items to correct program deficiencies and meet regulatory requirements are identified in the Pretreatment Audit Summary Table, 16 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 beginning on page 2 of this report. Specific actions to clarify and strengthen program implementation are provided as recommendations within the body of the audit report. 2.0 Publicly Owned Treatment Works (POTW) Information The BOPU owns and operates two POTWs that serve the boundary of Cheyenne and the South Cheyenne Water and Sanitation District, an outside contributing jurisdiction. The Crow Creek POTW, WY-0022381 is located at 4403 Livingston Ave, Cheyenne, WY 82007. The Dry Creek POTW is located at 8911 Campstool Rd, Cheyenne, WY 82007. The service area for the Crow Creek POTW is shown in Figure 1, the Crow Creek POTW process diagram is shown in Figure 2, and the Google Earth view of the Crow Creek is shown in Figure 3. The service area for the Dry Creek POTW is shown in Figure 4, the Dry Creek POTW process diagram is shown in Figure 5, and the Google Earth view of the Dry Creek POTW is shown in Figure 6. Narrative discussions of both POTWs were held and a site visit of the Dry Creek POTW was performed during the audit to develop an overview of the BOPU's POTW processes and operation. The POTW information and site visit was provided by Mr. Matt Buelow, Division Manager for the BOPU's POTWs. Service Area - The service area for the Crow Creek and Dry Creek POTWs are shown in Figure 1 - Crow Creek POTW Service Area and Figure 4 - Dry Creek POTW Service Area. As shown in the figures, the service area for the Crow Creek POTW includes the southwest portion of the City of Cheyenne, including the South Cheyenne Water and Sanitation District and the service area for the Dry Creek POTW includes the northeast portion of the City of Cheyenne. Crow Creek POTW - The Crow Creek POTW was built in 1947 and was the initial POTW for the City of Cheyenne, administered by the BOPU. The POTW is designed for a flow of 6.5 MGD with and actual flow of 2.8 - 3.3 MGD. The process flow diagram and a Google Maps view of the Crow Creek POTW are shown in Figures 2 and 3. The wastewater from the service area is conveyed to the Crow Creek POTW via a 30-inch interceptor into a wet well. The POTW has three centrifugal pumps, each with a capacity of 7 MGD to lift the wastewater to the headworks building. The flow enters two separate channels leading to parallel Vulcan step grinders to remove large solids and organic material; the barscreens that are automatically raked (cleaned). The screening material is washed and collected in a dumpster. The dumpster is transported to the landfill about every four days. The flow from the barscreens enters a Smith Loveless pista grit chamber for grit removal. The grit is then collected in a dumpster and transported to the landfill approximately every four days. The wastewater treated in the headworks flows to two primary clarifiers. The floating scum is skimmed and collected in a grease pit. The contents of the grease pit are sent to the Crow 17 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Creek interceptor that transports solids to the Dry Creek POTW. The primary clarifier solids are pumped from the bottom of the clarifiers to the Crow Creek interceptor. The primary clarifier effluent is sent to a splitter box and sent to the parallel Moving Bed Biofilm Reactor (MBBR) trains. The MBBR trains use specialized plastic media to create a moving bed where aerobic bacteria colonize and break down organic matter. Each train consists of two anoxic basins or zones followed by four aeration basins. Solids are returned to the anoxic zone to promote bacterial growth. The effluent from the MBBR is sent to two secondary clarifiers. The scum floating on top, and the settled solids are both collected and pumped to the Crow Creek interceptor leading to the Dry Creek POTW. The secondary effluent is sent to the ultra violet (UV) building, consisting of a single channel leading to the UV bank. The effluent from the UV is discharged to Crow Creek. The POTW also provides about 0.5 to 0.8 MGD to its onsite Reuse Plant. The BOPU adds aluminum sulfate to coagulate and the effluent passes through two sand filters. The reuse water is ready for reuse applications at city-owned landscape and golf courses. The BOPU uses about 70% for reuse and 30% for non-potable use. The BOPU injects sodium hypochlorite to the non-potable portion and stores this in two non-potable clarifiers. The Crow Creek POTW does not process solids as these are sent to the Dry Creek POTW via the Crow Creek interceptor. However, the Crow Creek POTW has drying beds that are used for collection of sand interceptors and utility solids collected by the City Collections division. The liquid in these drying beds is infrequently decanted and kiln dust is added to the solids which are sent to the landfill. Dry Creek POTW - The Dry Creek POTW was built in 1974 and is designed for a flow of 10.5 MGD with an actual flow of 2.8 - 3.3 MGD. The process flow diagram and a Google Maps view of the Crow Creek POTW are shown in Figures 5 and 6. The wastewater from the service area via the Dry Creek 30-inch interceptor. The Dry Creek POTW also receives solids from the Crow Creek POTW via the Crow Creek interceptor. The interceptors deliver wastewater to the headworks building where the wastewater is lifted to headworks with four screw pumps, each with a capacity of 7 MGD. The wastewater enters two separate channels headworks at the Dry Creek POTW. Each channel leads to a Vulcan step barscreen to remove large solids and organic material. The barscreens are automatically cleaned and the POTW manually cleans the screens twice a day. The screenings are washed, compacted and collected in a dumpster. The dumpster is sent to the landfill six days per week. The screened wastewater is sent to a grit chamber for grit removal. The grit settles out in the classifier and is collected into a 5-yard dumpster, that is transported to the landfill about every other day. The wastewater from the grit chamber is sent to a splitter box and sent to the primary clarifiers. The Dry Creek POTW has a total of four primary clarifiers, two on the north side of the POTW and two on the south side. The scum and other floatables from each clarifier are skimmed off and collected into a scum pit. The scum pit is regularly emptied by the 18 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Utilities department trucks and transported to the drying beds at the Crow Creek POTW. The settled primary solids are sent to the primary digester. The primary effluent is combined in a splitter box and split to the two anoxic basins for denitrification and two IFAS basins for BOD and ammonia removal. The effluent from the IFAS basins is sent to the three secondary clarifiers. The solids are returned to the anoxic/IFAS basins or about 6% of solids are wasted. The secondary effluent is sent to the UV disinfection building where it enters two separate channels leading to UV disinfection treatment. The effluent is discharged to Crow Creek and a portion is delivered to the nonpotable system. Solids - The wasted secondary clarifier sludge is sent to a rotary drum thickener, polymer is added, and the sludge is thickened to 2%. The thickened sludge is sent to the primary digester where it combines with the primary clarifier solids. The solids are maintained in the heated primary digester for about 15-18 days and transferred to a secondary, unheated storage digester for an additional 15-17 days. The sludge is dewatered in a screw press to about 14-15% and sent to onsite sludge drying beds. The sludge is turned periodically and stored to a solids percentage between 25 to 30%. The biosolids are Class A and are land applied in a ranch in Wyoming and one in Nebraska. 2.1 NPDES Permit The BOPU's NPDES permits #WY-0022934 for the Crow Creek POTW and #WY0022381 for the Dry Creek POTW, issued by the Wyoming Department of Environmental Quality (WYDEQ), contains provisions for an EPA-approved Pretreatment program in Part III.B. Both the Crow Creek and Dry Creek permits were effective on February 20, 2024 and expire on October 31, 2028. 19 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Figure 1 - Crow Creek POTW Service Area 20 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Figure 2 - Crow Creek POTW Process Diagram 21 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Crow Creek Drying Beds Figure 3 - Crow Creek POTW - Google Maps View 22 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Figure 4 - Dry Creek POTW Service Area 23 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Figure 5 - Dry Creek POTW Process Diagram 24 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Septic Disposal Station Figure 6 - Dry Creek POTW - Google Maps View 25 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 3.0 Resources 3.1 Resources Regulatory Background The Pretreatment Regulations found in 40 C.F.R. 403.8(f)(1-6) include POTW Pretreatment requirements and procedures to implement an approved Pretreatment program. These requirements and procedures include the legal authority and the implementation procedures of the Pretreatment program (permitting, inspections, sampling, industrial waste survey, receipt of IU reporting and notification, record-keeping, slug discharge control, data evaluation, and enforcement for non-compliance). In addition, the Pretreatment Regulations found in 40 C.F.R. 403.8(f)(3) state that the POTW shall have sufficient resources and qualified personnel to carry out the authorities and implementation procedures of the Pretreatment program. A Pretreatment program, in compliance with the criteria listed in the Pretreatment Regulations, requires adequate and qualified staffing to implement the Pretreatment program in its service area. The resources required for each implementation activity depend largely on the size of the service area, the number of IUs/SIUs/sector control programs, and Pretreatment program policies. A compliant program also requires a consistent funding mechanism to ensure the program is adequately funded and equipped to fully implement the program. 3.2 Evaluation of the BOPU`s Resources and Funding According to the CY24 Pretreatment Annual Report, the BOPU's resource commitment to the Pretreatment program is 4.15 FTE that includes a Compliance Supervisor, a Pretreatment Coordinator and two Pretreatment Specialists. The Compliance Supervisor provides oversight of the Pretreatment and Biosolids programs and develops SIU Pretreatment permits. The Pretreatment Coordinator and Specialists implement all programmatic activities such as the industrial user inventory/characterization, permitting, field activities such as inspections/sampling, compliance evaluation and enforcement. The Compliance Supervisor reports to the Division Manager, who reports to the Director and BOPU Board, which are appointed by the City of Cheyenne Mayor and City Council. The Pretreatment program is supported by the BOPU Attorney. The BOPU reported in its CY24 Pretreatment Annual Report that its Pretreatment program is budgeted at $501,510 and is funded by the BOPU's Sewer Enterprise Fund, generated from residential and non-residential users in the service area. The BOPU appears to be well equipped to implement the field activities of the Pretreatment program and has portable automatic samplers, sampling equipment, a dedicated truck, confined space entry equipment, and personal protective equipment. In addition, the BOPU has adequate storage space for its field equipment and access to the laboratory for cleaning, decontamination, and calibration of its equipment. Based on the EPA's review of the BOPU's implementation of its Pretreatment program, it appears that the BOPU's current resources and budget is adequate to implement all programmatic activities of the Pretreatment program, in compliance with 40 C.F.R. 403.8(f)(3). 26 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 3.3 Examples of Available Pretreatment Training/Resources The EPA recommends the BOPU continue to engage in available Pretreatment training opportunities to acquire the necessary training to ensure its personnel is qualified to implement the Pretreatment program. This is not a comprehensive list of all Pretreatment related training/resources available. The BOPU is encouraged to seek out training and resources that will support its Pretreatment program implementation. The EPA is also available to the BOPU for Pretreatment training opportunities, and during the Pretreatment audit, provided training on gathering information and characterizing IUs during facility inspections. The Region 8 Pretreatment workshop, provided by the Region 8 Pretreatment Association, provides training sessions directly related to Pretreatment implementation, updates to upcoming regulations and policies, and networking opportunities. The EPA provides "Pretreatment 101" webinar training designed to provide consistent national training to local and state Pretreatment programs. The webinar series is located at https://www.epa.gov/npdes/national-pretreatment-program-training-and-webinars. Archived presentations may be downloaded, and a schedule of future training opportunities is located at the website. An additional resource available is the Pretreatment Coordinators Group discussion forum, found at the following website: https://groups.io/g/Pretreatment/topics 4.0 Municipal Ordinance and Intergovernmental Agreements 4.1 Legal Authority Background The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1) states: "The POTW shall operate pursuant to legal authority enforceable in Federal, State, or local courts, which authorizes or enables the POTW to apply and to enforce the requirements of sections 307 (b) and (c), and 402(b)(8) of the Clean Water Act (Act) and any regulations implementing those sections. Such authority may be contained in a statute, ordinance, or series of contracts or joint powers agreements which the POTW is authorized to enact, enter into or implement, and which are authorized by State law. At a minimum, this legal authority shall enable the POTW to: i. Deny or condition new or increased contributions of pollutants, or changes in the nature of the pollutants to the POTW by Industrial Users where such contributions do not meet applicable Pretreatment Standards and Requirements or where such contributions would cause the POTW to violate its NPDES permit. ii. Require compliance with applicable Pretreatment Standards and Requirements by Industrial Users. 27 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 iii. Control through Permit, order, or similar means, the contribution to the POTW by each Industrial User to ensure compliance with applicable Pretreatment Standards and Requirements. In the case of Industrial Users identified as significant under 403.3(v), this control shall be achieved through individual permits or equivalent individual control mechanisms issued to each such User. iv. Require (A) the development of a compliance schedule by each Industrial User for the installation of technology required to meet applicable Pretreatment Standards and Requirements and (B) the submission of all notices and self-monitoring reports from Industrial Users as are necessary to assess and assure compliance by Industrial Users with Pretreatment Standards and Requirements, including but not limited to the reports required in 403.12. v. Carry out all inspection, surveillance and monitoring procedures necessary to determine, independent of information supplied by Industrial Users, compliance or noncompliance with applicable Pretreatment Standards and Requirements by Industrial Users. Representatives of the POTW shall be authorized to enter any premises of any Industrial User in which a Discharge source or treatment system is located or in which records are required to be kept under 403.12(o) to assure compliance with Pretreatment Standards. Such authority shall be at least as extensive as the authority provided under section 308 of the Act. vi. (A) Obtain remedies for noncompliance by any Industrial User with any Pretreatment Standard and Requirement. All POTW's shall be able to seek injunctive relief for noncompliance by Industrial Users with Pretreatment Standards and Requirements. All POTWs shall also have authority to seek or assess civil or criminal penalties in at least the amount of $1,000 a day for each violation by Industrial Users of Pretreatment Standards and Requirements. (B) Pretreatment requirements which will be enforced through the remedies set forth in paragraph (f)(1)(vi)(A) of this section, will include but not be limited to, the duty to allow or carry out inspections, entry, or monitoring activities; any rules, regulations, or orders issued by the POTW; any requirements set forth in control mechanisms issued by the POTW; or any reporting requirements imposed by the POTW or these regulations in this part. The POTW shall have authority and procedures (after informal notice to the discharger) immediately and effectively to halt or prevent any discharge of pollutants to the POTW which reasonably appears to present an imminent endangerment to the health or welfare of persons. The POTW shall also have authority and procedures (which shall include notice to the affected industrial users and an opportunity to respond) to halt or prevent any discharge to the POTW which presents or may present an endangerment to the environment or which threatens to interfere with the operation of the POTW. The Approval Authority shall have authority to seek judicial relief and may also use administrative penalty authority when the POTW has sought a monetary penalty which the Approval Authority believes to be insufficient. vii. Comply with the confidentiality requirements set forth in 403.14." 28 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 The provisions in 40 C.F.R. 403.8(f)(1)(i-vii) do not provide local Pretreatment programs with legal authority, but they do establish the minimum requirements for the local municipality to implement the Pretreatment program. A POTW's legal authority is derived from state law. Therefore, state law must confer the minimum legal authority required by the Pretreatment Regulations on a POTW. To apply the regulatory authority provided by state law, it is necessary for the POTW to establish local regulations to legally implement and enforce pretreatment requirements. A POTW's legal authority is typically established in a sewer use ordinance as part of the municipality's code, or in the case of a sanitation district, its Rules and Regulations. The EPA's 2007 Model Pretreatment Ordinance provides a template for POTWs that are required to develop pretreatment programs and can be found at the following website: https://www3.epa.gov/npdes/pubs/pretreatment_model_suo.pdf 4.2 BOPU Municipal Ordinance The EPA approved the BOPU's Pretreatment program on March 28, 1986. According to records maintained by the EPA, the BOPU has modified its Pretreatment program, including the following in the past ten years: Municipal Ordinance update to clarify language for the definitions, discharge prohibitions, use of best management practices in sector control programs, and certification language. - Approved by the EPA on May 3, 2022. Municipal Ordinance and enforcement response plan update to align with the Pretreatment Regulations - Approved by the EPA on November 28, 2023. The BOPU provided its Pretreatment legal authority found in Title 12-Public Service, Chapter 13.20-Wastewater Treatment and Disposal of its municipal ordinance for the EPA to review. The Pretreatment legal authority provide the BOPU the framework to implement the Pretreatment Regulations in the POTW's service area. 4.3 Inter-Jurisdictional or Governmental Agreements (IGA) 4.3.1 IGA Regulatory Background A POTW's authority to implement and enforce its approved Pretreatment program is directly related to its regulatory jurisdiction. The POTW's authority is established in its ordinance or Rules and Regulations, which are in effect for its service area. Local entities with connectors, or outside jurisdictions to the service area that contribute wastewater, must establish legally binding mechanisms to ensure that all IUs in these outside contributing jurisdictions are subject to enforceable Pretreatment standards and requirements, as required in 403.8(f)(1). 40 C.F.R. 403.8(f)(1)(i) states, "The POTW shall operate pursuant to legal authority enforceable in Federal, State or local courts, which authorizes or enables the POTW to apply and to enforce the requirements of sections 307 (b) and (c), and 402(b)(8) of the Act and any regulations implementing those sections. Such authority may be contained in a 29 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 statute, ordinance, or series of contracts or joint powers agreements which the POTW is authorized to enact, enter into or implement, and which are authorized by State law." [Emphasis added] The local entity that implements the Pretreatment program must either obtain this authority for itself through an IGA or ensure that the outside contributing jurisdiction has both the authority and the obligation to implement and enforce the Pretreatment Standards and Requirements against every IU that discharges to the POTW. 4.3.2 Evaluation of the BOPU's IGA with Outside Contributing Jurisdictions The BOPU has one outside contributing jurisdictions, South Cheyenne Water and Sanitation District (SCWSD) that discharges non-domestic wastewater to the BOPU's Crow Creek POTW. The SCWSD IGA modified on April 7, 2023 adequately delegates the BOPU authority to implement the Pretreatment program and enforce the Pretreatment Regulations. 5.0 Local Limits 5.1 Local Limits Regulatory Background The Pretreatment Regulations at 40 C.F.R. 403.8(f)(4) require POTWs that are developing pretreatment programs to develop and enforce specific limits on prohibited discharges or demonstrate that the limits are not necessary. 40 C.F.R. 403.5(c)(1) states, "Each POTW developing a POTW Pretreatment Program pursuant to 403.8 shall develop and enforce specific limits to implement the prohibitions listed in paragraphs (a)(1) and (b) of this section [general and specific prohibitions]. Each POTW with an approved pretreatment program shall continue to develop these limits as necessary and effectively enforce such limits." [Clarification and emphasis added]. The National Pretreatment Program consists of three types of national pretreatment standards established by regulation that apply to industrial users. These include prohibited discharge standards, categorical standards, and local limits. Prohibited discharge and categorical standards are developed by the EPA to establish nationwide Pretreatment Standards. Prohibited discharge standards, comprised of general and specific prohibitions found in the Pretreatment Regulations at 40 C.F.R. 403.5(a) and (b), apply to all IUs regardless of the size or type of operation. Categorical standards are uniform, technologybased standards that apply to specific process wastewater discharges from industrial categories. These categorical standards are found at 40 C.F.R. Parts 405 through 471. The EPA's promulgation of categorical standards does not relieve a POTW from its obligation to evaluate the need for and to develop local limits to meet the general and specific prohibitions in the Pretreatment Regulations. Because specific prohibitions and categorical standards provide only general protections against pass through and interference, local limits based on POTW-specific conditions may be necessary. Local limits are developed by POTWs to enforce the specific and general prohibitions, as well as any state and local regulations. 30 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 An EPA-approved Pretreatment program is required to develop technically based local limits that are protective of the POTW, the collection system, and the POTW's site-specific standards. These site-specific standards may be NPDES permit effluent limits, biosolids limits, environmental criterion, worker health and safety standards, or other local standards. The EPA recommends that POTWs establish their technically based local limits based on the maximum allowable headworks loading (MAHL) calculated for each pollutant of concern. The MAHL approach enables the POTW to calculate local limits considering the portion of the MAHL that is controllable (non-domestic discharges from IUs) from the uncontrollable portion (domestic sources, background concentrations, etc.). A pollutant's MAHL is determined by first calculating its Allowable Headworks Loading (AHL) for each POTW's site-specific standard or environmental criterion. Local limit development uses a mass-balance approach to determine the AHLs for a POTW based on the environmental and treatment plant criteria. An AHL is the estimated maximum loading of a pollutant that can be received at a POTW's headworks, that should not cause a POTW to violate a treatment plant limit or environmental criterion. An AHL is developed to prevent interference or pass-through. An AHL is calculated for each applicable POTW site-specific standard: pass-through, sludge contamination, air quality standards, and the various forms of interference (i.e., biological treatment inhibition, sludge digestion inhibition). The AHLs for each pollutant of concern (POC) are calculated based on the various suitable environmental criteria, plant flow rates, and plant removal efficiency. After calculating a series of AHLs for each POC, the lowest AHL is chosen as the MAHL. MAHLs estimate the maximum combined loadings that can be received at the POTW's headworks from all sources. Maximum allowable industrial loadings (MAIL), developed by the POTW, represent the amount of pollutant loadings the POTW can receive from controlled sources (i.e., industrial users, some commercial sources, and some hauled waste) that the POTW chooses to control through local limits. Local limits can take many forms based on how MAILs are allocated by the POTW. The designation and implementation of these MAILs, including the allocation of loadings to SIUs, are left to each POTW. The POTW should provide a reasonable method of allocating the MAIL to the SIUs while ensuring the implementation procedures do not exceed the calculated MAHL. Typically, the POTWs allocate the MAIL as a uniform concentration-based or a mass limit to each SIU. The local limits should be based on the following: Sampling of the service area to develop a representative data set collected for local limits (e.g., influent, effluent, biosolids, commercial, residential, industrial, trucked/hauled waste), Evaluation of the current POTW standards/criteria (including, but not limited to: NPDES permit limits/conditions, water quality standards, biosolids standards), Identification of the POTW removal efficiency and pollutant partitioning, Evaluation of data to ensure it is current and representative of current conditions, Identification of pollutants of concern, 31 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025  Calculations of loadings and determination of MAHL, and Development of local limits and allocation methods. 5.2 Local Limits Requirements Established in the BOPU's NPDES Permits The BOPU's NPDES permits for the Crow Creek POTW and the Dry Creek POTW, both issued by the WYDEQ on February 20, 2024, include Pretreatment requirements, including the requirement to establish, enforce and provide a technical evaluation of the BOPU's local limits within 12 months after permit renewal or February 20, 2025. 5.3 The EPA Evaluation of the BOPU's Local Limits 5.3.1 Technically based Local Limits The BOPU's current local limits were public noticed on April 27, 2015, by the EPA for a 30-day public comment period and approved by the EPA on June 3, 2015. The local limits were developed by the BOPU using SIU regulated flows located at the permitted monitoring points and are applicable to SIUs. The BOPU's local limits are incorporated in section 13.20.070 of the City of Cheyenne's municipal ordinance. The local limits applicability language in section 13.20.070(B) states the following: "It shall be unlawful for any significant industrial user or other designated and permitted industrial user to discharge or cause to be discharged any waste or wastewater to the Crow Creek Water Reclamation Facility or the Dry Creek Water Reclamation Facility that exceeds the following daily maximum limit or pollutant allocations as specified in the individual wastewater discharge permit established in Section 13.20.210 of this chapter and issued by the BOPU." Table 1 - Local Limits for the Dry Creek POTW Service Area Daily Maximum Total Maximum Pollutant Discharge Limits mg/L Allowable Industrial Load (MAIL)(1) lbs/day Arsenic 0.031 0.4348 Cadmium 0.008 0.1172 Chromium 2.43 34.0347 Copper 0.70 9.7646 Lead 0.187 2.6221 Mercury 0.0096 0.1343 Molybdenum 0.065 0.9110 Nickel 0.46 6.4162 Selenium 0.050 0.6962 Silver 0.133 1.8665 Zinc 1.67 23.4355 Biochemical Oxygen Demand 9788 9788 (BOD5), lbs/day 32 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Total Suspended Solid (TSS), lbs/day 10447 10447 Table 2 - Local Limits for the Crow Creek POTW Service Area Pollutant Arsenic Cadmium Chromium Copper Lead Mercury Nickel Selenium Silver Zinc Biochemical Oxygen (BOD5), lbs/day Total Suspended Solid lbs/day Demand (TSS), Daily Maximum Discharge Limits, mg/L 0.065 0.005 2.40 0.24 0.162 0.0023 0.69 0.040 0.165 3.04 4845 3071 Total Maximum Allowable Industrial Load (MAIL)(1) lbs/day 0.4625 0.0333 17.0625 1.7246 1.1543 0.0163 4.9048 0.2876 1.1763 21.6497 4845 3071 (1) The BOPU may allocate the MAIL for a pollutant on a case-by-case basis for the Crow Creek and Dry Creek facilities to significant industrial users or other permitted industrial user discharges. The total allocations included in individual wastewater discharge permits shall not exceed the lbs/day values listed. The BOPU will base its allocation decisions upon available loading and industrial user needs. Allocations are at the sole discretion of the BOPU. 5.3.2 Other Numeric Limits In addition to the established technically based limits in the municipal ordinance, the BOPU has established the following numeric limits by adoption in its municipal ordinance: [13-20-070(D)] - Total Petroleum Hydrocarbons - 50 mg/L and Total Fats, Oils and Greases - 100 mg/L [13-20-070(C)] - The following limits shall apply to wastewaters that are discharged from: o Groundwater cleanup of petroleum or gasoline underground storage tanks or other remediation wastewaters containing these pollutants. o Discharges where one or more of these pollutants are present; or o Where these pollutants are appropriate surrogates. 33 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 o It shall be unlawful for any industrial user to discharge or cause to be discharged any waste or wastewater to the POTW that exceeds the following limits: Total Benzene, 0.050 mg/L Total BTEX, 0.750 mg/L 5.3.3 Dilution Prohibition The BOPU has incorporated a prohibition on dilution in section 13.20.100 of its municipal ordinance to ensure the IUs are appropriately managing their regulated wastestreams to meet compliance with an applicable Pretreatment Standard or Requirement: "No industrial user shall ever increase the use of process water, or in any way attempt to dilute a discharge, as a partial or complete substitute for adequate treatment to achieve compliance with a discharge limitation unless expressly authorized by an applicable pretreatment standard or requirement. In addition to taking enforcement actions, the BOPU may impose mass limitations on industrial users who are using dilution to meet applicable pretreatment standards or requirements, or in other cases when the imposition of mass limitations is appropriate." The dilution prohibition language in 13.20.100 of the municipal ordinance meets the Pretreatment requirement in 40 C.F.R. Part 403.6(d). 5.4 Local Limits Technical Evaluation-Regulatory Background 40 C.F.R. 122.44(j)(2)(ii) of the NPDES regulations require POTWs to provide a written technical evaluation of the need to revise local limits following permit issuance or reissuance. The technical evaluation is a detailed re-evaluation of data, criteria, conditions, and assumptions on which local limits are based to determine whether any significant changes affecting the local limits have occurred. Chapter 7 of the Local Limits Development Guidance Manual, EPA-833-R-04-002A, July 2004 provides guidance on completing the technical evaluation of local limits. The Annual Pretreatment Reports submitted to the EPA provide the POTW with an opportunity to perform reviews for exceedances of the established MAHL for the POCs on an annual basis. The POTW compares both the maximum and average influent data for the reporting year against the MAHL to determine if there were any exceedances. In addition, the POTW is required to report biosolids data to determine if there were any changes or concerns with the biosolids loadings. An exceedance of the established MAHL may be indicative of a change in the service area, changes to the POTW operations, or changes to domestic or non-domestic loadings and may indicate a need to recalculate the local limits. However, the annual review may not have addressed conditions that can change over time, such as operating conditions, environmental criteria/standards, data, or assumptions that may make local limits no longer appropriate, protective, or legally defensible. As a follow-up to MAHL exceedances listed on the annual report and as required during a permit reissuance, a POTW should compare its current conditions and requirements with those that existed when the local limits were developed. The EPA recommends that 34 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 POTWs determine if re-calculating existing local limits or developing MAHLs for new pollutants of concern is necessary in response to the following criteria: 1. Removal Efficiencies a. Modification to the POTW or new POTW brought online. b. Changes in POTW processes or operations that have affected the POTW removal efficiencies. 2. Total POTW or IU Loading a. Significant changes to flow to the POTW. b. Significant changes to loadings to the POTW due to new IUs, changes in loadings at existing IUs, or significant growth in the service area. c. Significant changes in loadings from SIUs in the service area. 3. Limiting Criteria a. New or revised NPDES permit limits. b. New or revised biosolids standards. c. Changes in EPA or State Criteria (acute and chronic water quality standards for the receiving waters, reuse water quality criteria) at the time of local limit development to existing criteria. 4. Sludge Characteristics or Method of Disposal a. Changes in loadings to biosolids. b. Changes in biosolids disposal methods. 5. Background Concentrations of Pollutants in Receiving Water 5.5 Technical Evaluation of the BOPU's Local Limits The BOPU's NPDES permits for the Crow Creek POTW, and the Dry Creek POTW include the following requirements for technical evaluation of the local limits: "The Permittee shall establish and enforce specific local limits to implement the general and specific prohibitions found in 40 CFR 403.5(a) and (b). The Permittee shall continue to develop these limits as necessary and effectively enforce such limits. In accordance with 40 CFR 122.44(j)(2)(ii), a technical evaluation of the need to develop or revise local limits shall be submitted to the Approval Authority within 12 months of the effective date of this permit. This evaluation should be conducted in accordance with EPA's "Local Limits Development Guidance" July 2004. Where the Permittee determines that revised or new local limits are necessary, the Permittee shall submit the proposed local limits to the Approval Authority in an approvable form in accordance with 40 CFR 403.18." The technical evaluation established by the BOPU's permits are 12 months of the NPDES permit reissuance date or February 20, 2025. The BOPU began the technical evaluation condition by submitting the local limits sampling plan to the EPA on January 22, 2025. The BOPU also provided its Proposed Pollutants of Concern document to the EPA on March 10, 2025. Based on the EPA's evaluation, the BOPU is in compliance with the technical evaluation condition in its Dry Creek and Crow Creek NDPES permits. 35 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 The EPA recommends the BOPU evaluate the incorporation of adopted TPH and FOG numeric limits in its ordinance during the local limits update and determine the justification for these adopted limits. The EPA will provide the BOPU EPA guidance for Oil and Grease, "1975-April - Treatability of Oil and Grease Discharged to POTWs - EPA 440--175-066" to consider as a justification of adoption of TPH and FOG limits and include in the local limits' development records. The BOPU should also continue to use the "1989June - Model NPDES Permit for Discharges Resulting from the Cleanup of Gasoline Released from Underground Storage Tanks" as justification for the BTEX/Benzene adopted numeric limits. Include this justification in the local limits' development records. 5.6 Permit or Site-Specific Limits Local municipalities implementing the Pretreatment program should have the ability to establish site- or permit-specific limits as deemed necessary to be protective of the POTW. This is a beneficial authority because situations or projects may occur in the service area that the municipality may want to provide control to protect the POTW. However, the current limits in the ordinance may not address the pollutant of concern. The EPA considers the development of any local limit, whether codified in the municipal ordinance/rules and regulations or developed on a site-specific situation (i.e., permitsspecific limit), to be a program modification under 40 C.F.R 403.18 (53 FR 40579, Final Rule, General Pretreatment Regulations for Existing and New Sources, October 17, 1988). The development of any local limit is required to follow the approval and public notice provisions, both at the local level and by submitting to the EPA. The Pretreatment Regulations at 40 C.F.R 403.5(c)(3) states, "Specific effluent limits shall not be developed and enforced without individual notice to persons or groups who have requested such notice and an opportunity to respond." The EPA recommends that POTWs conduct public participation in the local limits process (whether codified in the municipal ordinances/rules and regulations or new limits developed in a permit) as openly as possible. This may involve notifying the SIUs/IUs and other affected parties of the proposed limits or announcing a 30-day public comment period. This would allow sufficient time for the public to participate, which is a fundamental goal of the Clean Water Act in Section 101(e). The BOPU has established the ability to develop site- or permit-specific limits in section 13.20.070(E) of its municipal ordinance: "The BOPU may establish more stringent pollutant limits, additional site-specific pollutant limits, BMPs, or additional pretreatment requirements, by ordinance or in individual wastewater discharge permits when, in the judgment of the BOPU, such limitations are necessary to implement the provisions of this chapter." 36 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 6.0 Pretreatment Operating Procedures 6.1 Regulatory Background The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2) states, "The POTW shall develop and implement procedures to ensure compliance with the requirements of a Pretreatment Program." [emphasis added] The Pretreatment Regulations identify these minimum procedures in 40 C.F.R. 403.8(f)(2)(i-viii) to include the following implementation activities, summarized below: Identify and locate all possible IUs that might be subject to the Pretreatment program, Obtain information describing the character and volume of wastes discharged by IUs, Notify IUs of all applicable Pretreatment standards and other applicable State or Federal standards or requirements, Review self-monitoring reports and other notices submitted by IUs, Randomly sample and analyze effluents from IUs, Evaluate whether each SIU needs a slug discharge control plan, Investigate instances of noncompliance with Pretreatment standards and requirements, Comply with public participation requirements. The requirements listed in 40 C.F.R. 403.8(f)(2) include the development of procedures. Adequate and updated standard operating procedures (SOPs) provide the following benefits to a Pretreatment program: Develop the baseline knowledge of the Pretreatment Regulations and establish the framework for program implementation, Adequately implement the authorities established in the municipal ordinance and ensure consistency in program implementation, Retain institutional and historical knowledge developed within the POTW's program, and Provide a valuable training resource for new or inexperienced staff members. Ultimately, the benefits of valid SOPs to the Pretreatment program are increased efficiency, improved data comparability, credibility, and legal defensibility. In addition, the development of written SOPs and templates allow the EPA to determine if the procedures adequately implement the legal authority developed in the municipal ordinance/rules and regulations as required in 40 C.F.R. 403.8(f): "A POTW Pretreatment program must be based on the following legal authority and include the following procedures. These authorities and procedures shall at all times be fully and effectively exercised and implemented." 37 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 6.2 Standard Operating Procedures (SOPs) The EPA evaluated the BOPU's procedures and templates during the audit to ensure these meet the requirements listed in 40 C.F.R. 403.8(f)(2). As previously discussed, developing SOPs are beneficial for the BOPU's Pretreatment program, but most importantly, it ensures adequate implementation of the authorities established in the municipal ordinance and ensures consistency in program implementation. The EPA considers the Industrial User Inventory and Characterization, Sampling Plan/QA-QC, and the Enforcement Response Plan to be priority and required SOPs to ensure consistent implementation of the BOPU's legal authority. The EPA evaluated these priority SOPs and provides comments in the following sections within this audit report: Industrial User Inventory and Characterization Procedures (discussed in 7.0), Sampling Plan, Site-Specific Sampling Protocol, Quality Assurance and Quality Control (discussed in 10.0), and Enforcement Response Plan and Data Compliance Evaluation (discussed in 11.0). In addition, the EPA evaluated the following SOPs submitted by the BOPU and these appear to be a valuable resource to ensure the BOPU is consistently implementing the programmatic activities of the BOPU's Pretreatment program: Industrial Pretreatment Program (IPP) Guidance Significant Non-Compliance (SNC) SOP The BOPU's current personnel have a mixture of experience in the program. Evaluating/updating the current IPP Guidance is a beneficial opportunity to incorporate the new perspectives of the current Pretreatment staff into the existing and new SOPs necessary to implement the program. 6.3 Templates Templates and checklists are also critical to a Pretreatment program to ensure consistent and appropriate implementation of the Pretreatment regulations. The BOPU has developed an industrial wastewater discharge survey, a permit application and a permit template. The discharge survey and the permit application appears to provide adequate information and data for the BOPU to develop an appropriate control mechanism. The evaluation of the permit template is included in 8.4 of this audit report. 6.4 Records and Data Management 6.4.1 Regulatory Background The recordkeeping requirements of the Pretreatment program are established in 40 C.F.R. 403.12(o)(1-3): "(1) Any Industrial User and POTW subject to the reporting requirements established in this section shall maintain records of all information resulting from any monitoring 38 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 activities required by this section, including documentation associated with Best Management Practices. Such records shall include for all samples: (i) The date, exact place, method, and time of sampling and the names of the person or persons taking the samples. (ii) The dates analyses were performed. (iii) Who performed the analyses. (iv) The analytical techniques/methods use; and (v) The results of such analyses. (2) Any Industrial User or POTW subject to the reporting requirements established in this section (including documentation associated with Best Management Practices) shall be required to retain for a minimum of 3 years, any records of monitoring activities and results (whether or not such monitoring activities are required by this section) and shall make such records available for inspection and copying by the Director and the Regional Administrator (and POTW in the case of an Industrial User). This period of retention shall be extended during the course of any unresolved litigation regarding the Industrial User or POTW or when requested by the Director or the Regional Administrator. (3) Any POTW to which reports are submitted by an Industrial User pursuant to paragraphs (b), [baseline monitoring reports] (d), [90-day compliance reports] (e), [categorical industrial user monitoring reports] and (h) [significant industrial user monitoring reports] of this section shall retain such reports for a minimum of 3 years and shall make such reports available for inspection and copying by the Director and the Regional Administrator. This period of retention shall be extended during the course of any unresolved litigation regarding the discharge of pollutants by the Industrial User or the operation of the POTW Pretreatment Program or when requested by the Director or the Regional Administrator." 6.4.2 Recordkeeping and Data Management Based on information gathered during the audit, the Pretreatment records for IUs and permitted SIUs are maintained in the file cabinets located in the IPP offices. The permitted SIU records are sequentially organized into the following sections: permit/spill plan/slug discharge control plan/correspondence/enforcement/sampling/SMRs/inspections. The truck and hauled waste records such as pre-inspection forms, insurance information, correspondence and applicable SDS are also maintained in the IPP offices. Food service FOG records are kept in the Specialist's offices and include manifests and applicable enforcement documentation. The working copies of the Pretreatment records are maintained in the IPP offices for three years and are archived in the storage room. Based on the EPA's evaluation, the Pretreatment records are well organized and maintained. The EPA acknowledges the Districts effort in maintaining the Pretreatment records as this is beneficial to the overall implementation of the BOPU's Pretreatment program. 39 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 6.5 Receipt of Discharge Monitoring Reports and Notifications The Pretreatment regulations in 40 C.F.R. 403.8(f)(2)(vii) require a POTW to "Investigate instances of noncompliance with Pretreatment Standards and Requirements, as indicated in the reports and notices required under 403.12 [IU compliance reports], or indicated by analysis, inspection, and surveillance activities [control authority monitoring]." This requires the POTW to ensure adequate receipt and tracking of self-monitoring reports and notifications. It also requires the POTW to have procedures to evaluate the data and information contained within these reports and notices, and determine compliance with the Pretreatment standards (e.g., permit limits and conditions). The BOPU accepts the compliance reports from the permitted SIUs, either through hand delivery or through the mail. The BOPU date stamps the reports and notices to determine if these compliance reports were submitted by the deadline due date required by the permit. The BOPU enters the data from the self-monitoring reports into the Linko database for compliance determination. The BOPU completes a compliance evaluation checklist for the permitted SIUs, to evaluate if all permit-limited pollutants were sampled and if they are in compliance. This checklist benefits the BOPU to ensure the reports are complete. The EPA recommends the BOPU update/modify the compliance evaluation checklist to include all permit required items, including: "Compliance report submitted by the due date" and other applicable narrative permit reporting conditions, Appropriate analytical methods used per 40 C.F.R. 136, and TTO certification, etc. The EPA will provide an example compliance report checklist for the BOPU to evaluate. 6.6 Management of Confidential Records The Pretreatment Regulations at 40 C.F.R. 403.14 establish the public availability of the Pretreatment records and the provisions to establish confidential business information (CBI). The BOPU has incorporated the public availability and confidentiality requirements in Section 13.20.160 of the municipal ordinance: "Information and data on an industrial user obtained from reports, surveys, wastewater discharge permit applications, individual wastewater discharge permits, general permits and monitoring programs, and from the BOPU's inspection and sampling activities, shall be available to the public without restriction, unless the industrial user specifically requests, and is able to demonstrate to the satisfaction of the BOPU, that the release of such information would divulge information, processes, or methods of production entitled to protection as trade secrets under applicable state law. Any such request must be asserted at the time of submission of the information or data. When requested and demonstrated by the industrial user furnishing a report that such information should be held confidential, the portions of a report which might disclose trade secrets or secret processes shall not be made available for inspection by the public, but shall be made available pursuant to a court order or subpoena, immediately upon request to governmental agencies for uses related to the WYPDES program or pretreatment program, and in enforcement proceedings involving 40 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 the person furnishing the report. Wastewater constituents and characteristics and other effluent data, as defined at 40 CFR Section 2.302, shall not be recognized as confidential information and shall be available to the public without restriction." According to information gathered during the audit, the BOPU has not received confidential business information. 7.0 Industrial User Inventory and Characterization 7.1 Regulatory Background The Pretreatment Regulations state in 40 C.F.R. 403.8(f)(2)(i-iii) that a POTW shall develop and implement procedures to ensure compliance with requirements of a Pretreatment Program. [These requirements are summarized after the regulation language in bold and italics font]. i. "Identify and locate all possible Industrial Users which might be subject to the POTW Pretreatment Program. Any compilation, index or inventory of Industrial Users made under this paragraph shall be made available to the Regional Administrator or Director upon request." This requires a POTW to develop and maintain an inventory of IUs in the service area. ii. "Identify the character and volume of pollutants contributed to the POTW by the Industrial Users identified under paragraph (f)(2)(i) of this section. This information shall be made available to the Regional Administrator or Director upon request." This requires a POTW to characterize the IUs in the inventory of the service area. iii. "Notify Industrial Users identified under paragraph (f)(2)(i) of this section, of applicable Pretreatment Standards and any applicable requirements under sections 204(b) and 405 of the Act and subtitles C and D of the Resource Conservation and Recovery Act. Within 30 days of approval pursuant to 40 C.F.R. 403.8(f)(6), of a list of significant industrial users, notify each significant industrial user of its status as such and of all requirements applicable to it as a result of such status." These procedures must include the notification of IUs of applicable Pretreatment Standards and other applicable requirements. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(6) state, "The POTW shall prepare and maintain a list of its non-domestic or Industrial Users meeting the criteria in 403.3(v)(1). The list shall identify the criteria in 403.3(v)(1) applicable to each Industrial User and, where applicable, shall also indicate whether the POTW has made a determination pursuant to 403.3(v)(2) that such Industrial User should not be considered a Significant Industrial User. The initial list shall be submitted to the Approval Authority pursuant to 403.9 or as a non-substantial modification pursuant to 403.18(d)." Approved Pretreatment programs are required by the Pretreatment Regulations to develop and maintain an inventory of IUs, in order to understand their service area and outside contributing jurisdictions. In addition, the Pretreatment Regulations require a Pretreatment program to characterize the IUs listed on the inventory and notify the IU of their status under the Pretreatment program. For example, the following characterizations may apply 41 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 to an IU, based on information received from questionnaires, drive-by or facility inspections: The IU is not characterized as significant, based on volume and characteristic of the discharged wastewater. The IU is characterized as significant and is issued a permit. The IU is not characterized as significant, but loadings need to be controlled using best management practices in a source control program such as a FOG program. The IU is generating wastewaters that are significant but does not discharge to the POTW and is characterized as a zero-discharging facility. The Industrial Waste Inventory and Characterization, or industrial waste survey (IWS)/IU inventory procedures are an important component of an effective Pretreatment program because this is a POTW's first exposure to the IUs, allows the POTW to determine if an IU is significant, notifies the IU of its status under the Pretreatment regulations, and determines the appropriate type of control mechanisms for these facilities to protect the POTW and collection system. 7.2 Industrial User Identification and Characterization Procedure The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2) require the BOPU to "develop and implement procedures" that "enable the POTW" to comply with Pretreatment Program requirements. The BOPU has not developed an Industrial User Inventory and Characterization Procedure SOP to implement the Pretreatment requirement found in 40 C.F.R. 403.8(f)(2)(i-iii). The requirement in 40 C.F.R. 403.8(f)(2)(i-iii) states that the BOPU must identify and locate all possible IUs which might be subject to the POTW Pretreatment Program, identify the character and volume of pollutants contributed to the POTW by the IUs, and notify the IUs of applicable Pretreatment Standards. According to information gathered from the audit, the BOPU collaborates with its Business License department to gather information on new businesses or existing IUs with tenant finishes. The Pretreatment program is assigned a task to sign off on these licenses in order for the certificate of occupancy to be issued after completion. In addition, the BOPU participates in regular Development Business Review meetings to gather information on new IUs in the service area. The BOPU sends out surveys to about 25% of its service area annually and based on the responses, may require additional inspections or sampling to complete the characterization of these IUs. It appears that the BOPU is devoting the necessary resources to maintaining the IU Inventory. The EPA recommends the BOPU develop a procedure that details how the BOPU maintains its IU inventory, how it characterizes pollutants and flows for these IUs and how it notifies the IUs of applicable Pretreatment Standards, based on the characterization. The development of the IU Inventory and Characterization procedure will benefit the BOPU to ensure consistency and to capture institutional knowledge and procedures. 42 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 7.3 Industrial User Database of the BOPU's Service Area The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(i-iii) require the BOPU to identify and locate all IUs in its service area, identify the character and volume of pollutants contributed by these IUs based on current information, and notify these IUs of applicable Pretreatment Standards and Requirements. The BOPU provided its current IU inventory of the IUs in its service area for the EPA to review. Based on the EPA's review, the BOPU's IU inventory contains about 1,500 IUs and appears to be current and representative of the POTW's service area. It also appears that the BOPU is devoting resources to continually maintain the inventory and capture current conditions of IUs in its service area. Based on the EPA's review of these IU Pretreatment records, it appears that two IUs do not contain adequate information or data to characterize the pollutants and loadings, as required in 40 C.F.R. 403.8(f)(2)(ii). The BOPU needs to conduct a facility inspection at Eagle Claw Manufacturing to gather information on the processes conducted at the facility, as a follow up to the facility's submitted IU survey. In addition, the BOPU needs to either send a survey to Koontz Tooling or conduct a facility inspection to maintain the IU inventory. The results of the IU inventory follow up activities for Eagle Claw Manufacturing and Koontz Tooling need to be submitted to the EPA as follow-up to the audit. The EPA currently provides "Pretreatment 101" webinar training, and a training for "Industrial User Inventory and Characterization Procedures," was provided in September 2010. The training is archived at the following website: https://www.epa.gov/npdes/national-pretreatment-program-events-training-andpublications#pretreat101 8.0 Evaluation of Pretreatment Records and Permit Specific Issues 8.1 Regulatory Background POTWs are required to issue control mechanisms to IUs identified as SIUs through IU Inventory and Characterization procedures. Individual permits or general control mechanisms authorize the discharge of wastewater to a POTW upon condition that the discharger complies with the permit limitations and conditions. An SIU permit is effective for only a limited period and should be revocable by the issuing authority at any time for just cause. In addition, the POTW's legal authority will typically include a provision that forbids the discharge of industrial wastewater from a SIU without a current permit. The Pretreatment Regulations establish the required permit conditions in 40 C.F.R. 403.8(f)(1)(iii)(B)(1-6) that include the following minimum elements: 1. Statement of duration (in no case more than five years). 2. Statement of non-transferability without, at a minimum, prior notification to the POTW and provision of a copy of the existing control mechanism to the new owner or operator. 43 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 3. Effluent limits, including Best Management Practices, based on applicable general Pretreatment Standards, categorical Pretreatment Standards, local limits, and state and local law. 4. Self-monitoring, sampling, reporting, notification and recordkeeping requirements, including an identification of the pollutants to be monitored, sampling location, sampling frequency, and sample type, based on the applicable general Pretreatment Standards, categorical Pretreatment Standards, local limits, and state and local law. 5. Statement of applicable civil and criminal penalties for violation of Pretreatment Standards and requirements, and any applicable compliance schedule. Such schedules may not extend the compliance date beyond applicable federal deadlines. 6. Requirements to control Slug Discharges, if determined by the POTW to be necessary. The reporting and notification requirements in permit condition #4 above are found in 40 C.F.R. 403.12 of the Pretreatment Regulations and include the following: Baseline Monitoring Reports - 403.12(b) Compliance Schedule Progress Reports - 403.12(c) 90-Day Compliance Reports - 403.12(d) CIU Periodic Compliance Reports - 403.12(e) Notice of Potential Problems, including Slug Loading - 403.12(f) Notification of Changes Affecting Slug Discharge Potential - 403.8(f)(2)(vi) 24-Hour Non-Compliance Notification - 403.12(g) SIU Periodic Compliance Reports - 403.12(h) Notification of Changed Discharge - 403.12(j) Notification of Hazardous Waste Discharge - 403.12(p) Notification of Bypass - 403.17 Under general principles of administrative law, permit applicants and other interested parties may challenge the POTW's permit decisions, including the permit limitations and conditions and the POTW's authority to issue the permit. The POTW must ensure that it has the requisite legal authority to impose Pretreatment Standards and Requirements in SIU permits and that it exercises its authority in a consistent and non-arbitrary manner. The local ordinance must clearly provide the POTW with the following authorities to support the permit requirements found in 40 C.F.R. 403.8(f)(1)(iii): Authority to regulate all Industrial Users contributing wastewater to the POTW. Authority to require and issue permits, orders, or other control mechanisms, including: o Authority to require Industrial Users to submit all data that the POTW deems relevant to permit decisions and provisions for public access to data. o Authority to enter, inspect, and sample to verify information supplied by the Industrial User as well as to assess the Industrial User's compliance status. o Authority to incorporate local limits, including BMPs (if applicable). o Authority to incorporate federal and state Pretreatment Standards and Requirements. 44 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 o Authority to require self-monitoring, record keeping, reporting, and notifications by the permittee. o Authority to develop other appropriate permit conditions. Authority to enforce sewer use ordinance and discharge permit violations. Authority to require the development of a slug discharge control plan. The POTW is required to establish the legal authority to require an IU to complete and file a permit application, with current information, to receive an initial or reissued permit. A permit application enables the POTW to obtain the information necessary to characterize the facility, to evaluate the quality and quantity of wastewater discharged or projected to be discharged for a new facility, and to determine the applicable Pretreatment Standards and controls. The permit application serves as the formal request from the IU to discharge to the POTW and is required to be signed by a responsible corporate officer of the IU, as defined in 40 C.F.R. 403.12(l) of the Pretreatment Regulations. In addition to the permit application, the POTW should evaluate, if available, historic IU effluent data, compliance reports, previous inspection reports, Safety Data Sheets, etc. Throughout the permit drafting process, the POTW should carefully and thoroughly document each step in a permit rationale or statement of basis. A statement of basis is a document that provides a justification of the permit conditions and limits based on a characterization of the IU, its wastewater discharge, and the applicable Pretreatment Standards and Requirements. The statement of basis should include a description of the facility's production, process(es), wastewater generation/management, and discharge locations to adequately characterize the facility. The statement of basis should also identify the appropriate federal, state, and local Pretreatment Standards, based on the IU's characterization and should provide justification for permit conditions and requirements, such as pollutants of concern, monitoring/reporting frequencies, representative sampling types, notification requirements, slug discharge control, operation and maintenance requirements, etc. The statement of basis facilitates defending any challenges that the permit terms and conditions were developed arbitrarily or capriciously and provides the required documentation in the permit record of any relief from otherwise applicable requirements (i.e., pollutants not expected to be present, equivalent limits, decisions on general control mechanisms, decisions on Non-Significant Categorical Industrial User (NSCIU) classification, and decisions on reduced monitoring requirements). In addition, the statement of basis can serve as a resident document to preserve institutional knowledge and continuity for new or different staff members. The EPA updated the IU Permitting Guidance Manual, 833-R-12-0001A, in September 2012. This guidance manual supports the implementation of the permit conditions found in 40 C.F. R. 403.8(f)(1)(iii)(B)(1-6) of the Pretreatment Regulations. The guidance manual is intended to provide both new and experienced permit writers with conceptual support and specific examples to strengthen their permit development expertise. The guidance manual references technical guidance developed by the EPA regarding local limits, enforcing Pretreatment Standards and Requirements, controlling hauled waste, information regarding compliance inspections and sampling, and BMPs. 45 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 The IU Permitting Guidance Manual can be found at the following website: https://www.epa.gov/sites/production/files/201510/documents/industrial_user_permitting_manual_full.pdf 8.2 The EPA's Evaluation of the BOPU's Permitting Legal Authority The EPA evaluated the BOPU's municipal ordinance to ensure it provides an adequate framework to require permit coverage, to deny or condition non-domestic wastewater contributions and to establish adequate permit conditions. Section 13.20.210(A) - establishes the requirement for SIUs and CIUs to obtain a wastewater discharge permit. Section 13.20.210(B) - establishes the requirement for other IUs to obtain a wastewater discharge permit, if applicable. Section 13.20.240 - contains the permit application contents. Section 13.20.090 and 13.20.270 - establishes the authority for the BOPU to deny or condition wastewaters discharged to the public sewers. Section 13.20.280(A) - establishes the permit conditions to prevent Passthrough or Interference to protect the POTW, worker health and safety, biosolids, and the receiving stream water quality. 8.3 Permit Template Overview The EPA evaluated the BOPU's permit template to ensure the BOPU is incorporating the required permit conditions found in 40 C.F.R. 403.8(f)(1)(iii)(B)(1-6) of the Pretreatment Regulations and section 13.20.280(A) of the BOPU's municipal ordinance. The results of the EPA's review of the BOPU's permit template is found in Section 8.4.3. 8.4 Specific Permit Record Findings The BOPU has identified seven IUs in the service area that are determined to be SIUs and that have been issued a permit under the Pretreatment program. One of the SIUs, Black Hills Energy, has been identified as a categorical industrial user (CIU) subject to the Steam Electric Categorical Pretreatment Standards developed by the EPA and found in 40 C.F.R. 423. The other six SIUs are subject to the BOPU's local limits or are zero discharge. The EPA reviewed the Pretreatment records from a representative number of SIUs, CIUs and zero discharge permittees. Findings and observations from the EPA's review of the Pretreatment records, including the facility inspection report, statement of basis, permit, compliance evaluation, and enforcement records are listed below: 8.4.1 Permit records Overview 1. SIU Facility Inspection Reports: The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(ii) require the BOPU to "Identify the character and volume of pollutants contributed to the POTW." Based on the EPA's review of the BOPU's Pretreatment records, the BOPU is inspecting the SIUs at least annually. 46 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 a. The SIU inspection reports include only brief descriptions of the manufacturing processes. The inspection reports should include more detail regarding the SIU's chemical storage/handling/transfer, process/unit operations, wastestream generation from these unit operations, wastestream management or wastewater treatment, and sampling procedures, in order to provide a detailed and current characterization (including an evaluation of slug discharge potential and process or treatment plant changes). This information is important for capturing current conditions and determining if a control mechanism (such as an SIU permit or BMPs) or a modification to an existing control mechanism (such as a slug discharge control plan or spill plan) are necessary. b. The EPA recommends the BOPU gather digital photos during facility inspections and ensure these photos capture areas relevant to the Pretreatment permit. These areas could include but are not limited to, floor drains, unit operations, raw material/chemical storage, applicable chemical handling equipment, wastestreams, wastewater treatment, and discharge locations/monitoring points. If digital photos are taken during an inspection, the EPA recommends including them in the facility inspection reports. c. The BOPU provides a follow up letter after an inspection. The EPA recommends the BOPU include a statement in the letter, that the IU is responsible to notify the BOPU if process changes occur that may alter the evaluation. d. During the audit, the EPA provided compliance assistance and training on the following: i. Conducting facility inspections, ii. Gathering data and information, and iii. Generating inspection reports that provide current facility conditions (since these may impact categorical determinations, permit conditions, or control documents such as the slug discharge control plan or toxic organic management plans). 2. Statement of Basis: The BOPU develops a statement of basis for every issued SIU and zero discharge permit. The statement of basis adequately captures current conditions at the SIUs, identifies applicable Pretreatment Standards and justifies the permit conditions. It also contains representative monitoring type/frequencies based on the SIU's wastewater discharge, recent compliance history, slug discharge/spill potential, reporting frequency, reportable data, TOMP requirements, and the requirements for a slug discharge control plan based on the current conditions. 3. Permit Template: Based on the EPA's review, the BOPU's permit template and the standard conditions are equivalent to the Federal Pretreatment Regulations found in 40 C.F.R. 403.8(f)(1)(iii)(B)(1-6) and adopted in the BOPU's municipal ordinance at section 13.20.280(A). 47 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 a. The BOPU issues discharge and zero discharge permits for three years. The BOPU's Permit Template allow the permit to be administratively extended and include the following statement on the cover page: "If the Permittee wishes to continue to discharge beyond the expiration date of this Permit, an application must be submitted to the BOPU in accordance with the requirements of applicable Cheyenne City Code, Title 13, Chapter 13.20. To be eligible for permit reissuance and to continue to discharge industrial wastewater to BOPU, applications must be received by the BOPU a minimum of 90 days prior to the expiration date of this Permit." The EPA recommends the BOPU clarify this administrative extension to align with its legal authority in section 13.20.220 of the municipal ordinance. To aid in this clarification, the EPA recommends adding the following language: "This shall not apply if the duration of the wastewater discharge permit is five years or if the administrative extension is five years from the issuance date." b. The BOPU has a zero discharger IU in its service area and has not developed a zero-discharge permit template. The EPA is providing an "EPA Region 8 Zero Discharge Permit Template" for the BOPU to evaluate and consider using for zero-discharging IUs in its service area. 4. Recordkeeping: Based on the EPA's evaluation of the Pretreatment records, it appears that the BOPU needs to improve its recordkeeping to ensure the reports are adequately evaluated and filed in a timely manner. 5. Slug Discharge Control Plans - Based on the EPA's review of the Pretreatment records, the BOPU has ensured the permitted SIUs develop a slug discharge control plan that captures current conditions at the SIU and adequately implements the required elements found in the Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(vi)(A-D). 8.4.2 Black Hills Energy 1. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(ii) require the BOPU to "Identify the character and volume of pollutants contributed to the POTW." The EPA evaluated the 2023 and 2024 facility inspection reports the BOPU conducted at Black Hills Energy. The 2024 inspection report only includes brief descriptions of the steam electric process, oil/water separator, sludge disposal method and is missing flow information. The inspection report should contain information regarding the generation of wastewater from the steam electric turbines, water supply treatment, a description of the boiler cleaning (if applicable), and management of PCB disposal (if applicable). The inspection report should also adequately describe the cooling tower management, including chemical usage and discharge from the cooling towers to ensure the sampling/monitoring is representative. 48 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 a. In addition, the 2024 inspection report appears incomplete. The report is missing flow data information, information to determine if the SIU's sampling facilities are in satisfactory condition, a clear determination of proper sludge management, and records reviewed. Additionally, the 2024 inspection report is not signed and dated. b. The BOPU is required to ensure its inspection reports are complete and contain adequate information to characterize current conditions at the facility. 2. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(iii)(B)(3) state that a permit must be enforceable and contain the following elements: "Effluent limits, including Best Management Practices, based on applicable general Pretreatment Standards in part 403 of this chapter, categorical Pretreatment Standards, local limits, and State and local law." a. The Steam Electric Point Source Categorical Pretreatment Standards for New Sources (PSNS) at 40 C.F.R. 423.17(b)(1) state that "There shall be no discharge of polychlorinated biphenyl compounds such as those used for transformer fluid." The Black Hills Energy permit does not include this PCB discharge prohibition. The BOPU is required to modify the current Black Hills Energy permit to include this PSNS. b. Part I, section A.1 of the Black Hills Energy permit allows reverse osmosis (RO) reject water to be introduced into outfall 001. The outfall 001 is the monitoring point for regulated cooling tower blowdown and the introduction of RO reject water is a dilution wastestream. The facility is required to eliminate the introduction of RO reject wastewater to outfall 001 or the BOPU is required to modify the permit to calculate limits based on the combined wastestream formula to account for the RO dilution wastestream. c. Part I, section A.3 of the Black Hills Energy permit contains the applicable limits for cooling tower blowdown for Chromium and Zinc at outfall 001. However, the permit does not include the 126 priority pollutants contained in chemicals added for cooling tower maintenance or an allowance for engineering calculations, required at 40 C.F.R. 423.17(a)(4)(i). The Steam Electric PSNS at 40 C.F.R. 423.17(a)(4)(ii), allows the facility to: to determine the priority pollutants through engineering calculations that demonstrate that the regulated pollutants are not detectable in the final discharge by (by the analytical methods used in 40 C.F.R. part 136), instead of the monitoring in compliance with the standards for the 126 priority pollutants. d. The BOPU established local limit loadings for BOD at 9,788 lbs/day and TSS at 19,447 lbs/day for all SIU discharges to the Dry Creek POTW. The BOPU has allocated 100% of the BOD and TSS local limits loading to Black Hills Energy in its permit. The BOPU needs to re-evaluate the 100% 49 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 allocation to Black Hills as this restricts the BOPU from allocating BOD and TSS loadings to other SIUs discharging to the Dry Creek POTW. 3. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(iii)(B)(4) state that a permit must be enforceable and contain the following elements: "Selfmonitoring, sampling, reporting, notification and recordkeeping requirements, sampling location, sampling frequency, and sample type, based on the applicable general Pretreatment Standards, categorical Pretreatment Standards, local limits, and State and local law." The Pretreatment Regulations at 40 C.F.R. 403.12(h) state that the Control Authority must require appropriate reporting from those Industrial Users with discharges that are not subject to categorical Pretreatment Standards. Significant Non-categorical Industrial Users must submit to the Control Authority at least once every six months a description of the nature, concentration, and flow of the pollutants required to be reported by the Control Authority. These reports must be based on sampling and analysis performed in the period covered by the report, and in accordance with the techniques described in 40 CFR part 136. a. Part II, section A.3 of the Black Hills Energy permit only requires annual sampling for Pb, Ni, Ag, TPH and BTEX at outfall 003. The BOPU is required to modify the permit to require at a minimum, semi-annual sampling at outfall 003 for all permit-limited pollutants of concern. 8.4.3 Cheyenne Renewable Diesel Company (CRDC) 1. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(iii)(B)(3) state that a permit must be enforceable and contain the following elements: "Effluent limits, including Best Management Practices, based on applicable general Pretreatment Standards in part 403 of this chapter, categorical Pretreatment Standards, local limits, and State and local law." a. The BOPU established local limit loadings for BOD at 4,845 lbs/day and TSS at 3,071 lbs/day for all SIU discharges to the Crow Creek POTW. The BOPU has allocated 100% of the BOD and TSS local limits loading to CRDC in its permit. The BOPU needs to re-evaluate the 100% allocation to CRDC as this restricts the BOPU from allocating BOD and TSS loadings to other SIUs discharging to the Crow Creek POTW. 8.4.4 Walmart Distribution Center 1. The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(iii)(B)(4) state that a permit must be enforceable and contain the following elements: "Selfmonitoring, sampling, reporting, notification and recordkeeping requirements, sampling location, sampling frequency, and sample type, based on the applicable general Pretreatment Standards, categorical Pretreatment Standards, local limits, and State and local law." Further, the Pretreatment Regulations at 40 C.F.R. 403.12(g)(3) require the reports required must be based upon data obtained through appropriate sampling and analysis performed during the 50 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 period covered by the report, which data are representative of conditions occurring during the reporting period. a. The BOPU requires sampling for permit-limited metals to be conducted as a 24-hour composite, except for mercury which is sampled as a grab sample. The EPA is not aware why mercury is required as a grab sample instead of a 24-hour composite similar to other permit-limited metals. The BOPU is required to evaluate the sample type for mercury to ensure the sample type is representative of discharges for the production day. 2. Based on the EPA's review of the Pretreatment records, the 1st Quarter 2024 self-monitoring compliance report due on April 30, 2024 was not date stamped as received by the BOPU. As a result, the EPA was unable to determine if the report was received by the due date required by the permit. The BOPU is required to ensure it consistently date stamps the reports and notifications received to determine compliance with the due dates. 8.4.5 Dystar Foam Control 1.The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(ii) require the BOPU to "Identify the character and volume of pollutants contributed to the POTW." The EPA evaluated the 2023 and 2024 facility inspection reports the BOPU conducted at Dystar Foam Control. The 2024 inspection report only includes brief descriptions of the defoamer manufacturing, raw materials and wastestream management. The inspection report should contain information regarding the raw materials receipt at the outside tank farm and in the warehouse, it should also include handling and transfer to the blending tanks. In addition, the inspection report should contain information regarding wastestream generation and management. 2.The EPA conducted an oversight facility inspection at Dystar Foam Control on January 28, 2025, as part of the Pretreatment audit of the BOPU. The inspection report was submitted to the facility on March 12, 2025. The inspection report and cover letter were submitted to the facility on March 27, 2025, and are enclosed with this audit report. a. Based on observations from the facility inspection, the EPA observed a constructed trench drain in the Cold Storage Room. The trench drain is not equipped with a pump to convey spills or leaks to the wastewater storage tank and is only used for containment of potential spills. The facility stated during the inspection that the room is not used for liquid storage. b. Based on observations from the facility inspection, an open floor drain leading to the BOPU's sanitary sewer exists within the retaining wall of tank #17 located in the warehouse. Although the tank is not used according to facility representatives, the open floor drain represents a potential slug discharge to the BOPU in case of inadequate training or operator error when managing spills occurring in the warehouse. This may result in a violation 51 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 of the facility's zero-discharge permit. The EPA recommends the facility permanently plug the open floor drain to eliminate any slug discharge potential. c. The EPA recommends the SIU develop a slug discharge control plan to ensure the proper management of spills that may occur from the large volume of liquid stored in the warehouse and cold storage room. 9.0 Significant Industrial User Facility Inspections 9.1 Regulatory Background The General Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(v) state that the POTW shall have the legal authority to: "Carry out all inspection, surveillance, and monitoring procedures necessary to determine, independent of information supplied by Industrial Users, compliance or noncompliance with applicable Pretreatment Standards and Requirements by Industrial Users. Representatives of the POTW shall be authorized to enter any premises of any Industrial User in which a Discharge source or treatment system is located or in which records are required to be kept under 403.12(o) to assure compliance with Pretreatment Standards. Such authority shall be at least as extensive as the authority provided under section 308 of the Act;" The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(v) require the POTW to inspect its SIUs at least once per year. 40 C.F.R. 403.8(f)(2)(ii) requires the BOPU to "Identify the character and volume of pollutants contributed to the POTW." 40 C.F.R. 403.8(f)(2)(vii) establishes the standard of evidence collection during sampling or inspection activities: "Investigate instances of noncompliance with Pretreatment Standards and Requirements, as indicated in the reports and notices required under 403.12, or indicated by analysis, inspection, and surveillance activities described in paragraph (f)(2)(v) of this section. Sample taking and analysis and the collection of other information shall be performed with sufficient care to produce evidence admissible in enforcement proceedings or in judicial actions." Typically, an inspector is the only representative from the POTW that regularly appears at the IU's facility and significantly represents the POTW's role as a responsible public agency, observing the actions and evaluating the performance of the regulated industry. 9.2 Right of Entry The BOPU has established the authority for right of entry in 13.20.170 of its municipal ordinance: "The BOPU shall have the right to enter the premises of any industrial user to determine whether the industrial user is complying with all requirements of this chapter and any 52 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 individual wastewater discharge permit, general permit, or order issued hereunder. Industrial users shall allow the BOPU ready access at all times to all parts of the premises for the purposes of inspection, sampling, records examination and copying, including use of digital photography, recording equipment, and the performance of any additional duties. A. Where an industrial user has security measures in force which require proper identification and clearance before entry into its premises, the industrial user shall make necessary arrangements with its security guards so that, upon presentation of suitable identification, the BOPU shall be permitted to enter without delay for the purposes of performing specific responsibilities. B. The BOPU shall have the right to set up on the industrial user's property, or require installation of, such devices as are necessary to conduct sampling and/or metering of the industrial user's operations. C. The BOPU may require the industrial user to install monitoring equipment as necessary. The facility's sampling and monitoring equipment shall be maintained at all times in a safe and proper operating condition by the industrial user at its own expense. All devices used to measure wastewater flow and quality shall be calibrated per the manufacturer's specifications or once per year, whichever is less. D. Any temporary or permanent obstruction to safe and easy access to the facility to be inspected and/or sampled shall be promptly removed by the industrial user at the written or verbal request of the BOPU and shall not be replaced. The costs of clearing such access shall be borne by the industrial user. E. Unreasonable delays in allowing the BOPU access to the industrial user's premises shall be a violation of the provisions of this chapter." The municipal ordinance adequately establishes the right of entry authority for the BOPU, as required in the Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(v). 9.3 Facility Inspection Records - Background The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(vii) require the POTW to meet the criterion for evidence collection "with sufficient care to produce evidence admissible in enforcement proceedings or in judicial actions." This is performed during facility inspections by adequate documentation (in the inspection report) of the observations, surveillance, inspections, sampling performed, and analysis gathered during the facility inspections. A complete and well-developed inspection report that provides a current characterization of the facility will benefit the POTW's Pretreatment program for programmatic decisions such as categorical determinations, slug discharge/spill potential, changes at the facility that may affect the current permit conditions, sampling frequencies, etc. As discussed in 2.11.2 of the Industrial User Inspection and Sampling Manual for POTWs, EPA-831B17001, January 2017, the inspection report generated from the facility inspections should accomplish the following three objectives: 53 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 1. organize and coordinate all information in a comprehensive, usable manner for use by the POTW's compliance personnel; 2. identify areas that may require follow-up activity; and 3. provide significant background information on the facility that can be reviewed prior to conducting subsequent inspections at the facility. The quality of this documentation will, to a large degree, determine how effective these follow-up activities will be at the facility. The information in the inspection report must be presented in a clear, concise, and well-organized manner. The Industrial User Inspection and Sampling Manual for POTWs describes the information necessary to characterize a facility in 2.10.3 and 2.12. The manual also discusses the records to review at a facility to help determine the facility's compliance in 2.10.8. It is important for Pretreatment programs to capture the following information during facility inspections to characterize the facility, and document facility changes to ensure the SIU's permit addresses current conditions: Chemical storage areas, including potential spill concerns during chemical receiving, transfer, and handling. Process tanks or processing areas - detailed descriptions of the processes occuring on-site, including tank contents and capacities. Wastestream generation from the process areas and disposal/discharge practices - frequency of discharge of rinse water tanks. Spent chemical solutions tanks and whether they discharge to the POTW or are hauled off site; proximity to floor/trench drains, slug discharge control, and spill containment measures, etc. Wastestream management (treatment, recycling, hauling off site, evaporation, etc.). Waste treatment system. Wastestream or hazardous waste storage areas, including potential spill concerns. Discharge monitoring points. o Evaluation of the sampling/monitoring protocols to determine if these are appropriate to provide representative data of the wastewaters regulated by the permit. A facility inspection of a permitted SIU should include a review of relevant records used to support compliance with the permit conditions, and records that may not be reported in the self-monitoring compliance reports; such as pH and continuous flow monitoring records, tank change-out logs, analytical reports, waste manifests, operation and maintenance logs, etc. A detailed facility inspection report with descriptions of tank contents, capacities, generated wastestreams, plumbing, and management of the wastestreams will benefit the POTW to establish the baseline for the year. It will also help to determine if any changes will impact the permit conditions/limits or associated documents such as the slug discharge control plan, spill plan, treatment system operation manual, or sampling protocol. During the Pretreatment audit, the EPA discussed inspection procedures with the BOPU, including the EPA's procedures. The EPA performs facility inspections by gathering verbal or narrative information in an opening conference, then performing a walkthrough to 54 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 visually confirm the information gathered during the opening interview. The EPA structures its information gathering by following the raw materials/chemical supply through the sequential unit operations and ultimately to the finished product or service. Any wastestreams that are generated from the unit operations are compiled and questions are asked about the management or treatment of such wastes. This includes discharges to the municipality, hauling off-site or other disposal/recycling/reuse methods. A closing conference is performed to gather follow-up information, review records, and to provide preliminary conclusions to the facility. 9.4 Evaluation of the BOPU's Inspection Reports/Records The EPA evaluated the inspection reports and other records related to the facility inspection for the SIU annual facility inspection. As discussed in section 8.4.1.1 of this audit report, the SIU inspection reports provide minimal characterization of the facility and need to be improved to include the following information: information regarding the facility's chemical storage/handling, process (sources, flow volume, and types of discharges), wastewater generation, slug discharge potential, waste treatment methods, sampling procedures, and review of records in the annual inspection report. The inspection reports should also include digital photos to further support information gathered during the inspection. 9.5 Notification of Applicable Pretreatment Standards The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(iii) require the BOPU to notify IUs of applicable Pretreatment Standards and Requirements. Based on the EPA's review of the inspection records, it appears that the BOPU is consistently providing notification to the SIUs regarding the applicable Pretreatment Standards and applicable corrective action items as a follow-up to the facility inspections. The EPA recommends the BOPU include a statement that the IU is responsible to notify the BOPU if process changes occur that may change the evaluation. 9.6 Facility Inspections During the audit, the EPA and the BOPU inspected Dystar Foam Control on March 12, 2025. The inspection report was submitted to the facility on March 27, 2025 and is included in this audit report as an enclosure. Areas of concern during the facility inspection are provided in the facility inspection reports for the BOPU to provide direct follow-up with the inspected facility. 10.0 Control Authority Compliance Monitoring 10.1 Regulatory Background The Pretreatment Regulations at 40 C.F.R. 403.8(f)(1)(v) require the POTW to have the legal authority to "Carry out all inspection, surveillance, and monitoring procedures necessary to determine, independent of information supplied by Industrial Users, compliance or noncompliance with applicable Pretreatment Standards and requirements." Further, 40 C.F.R. 403.8(f)(2)(v) requires a POTW to "Randomly sample and analyze 55 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 the effluent from Industrial Users and conduct surveillance activities in order to identify, independent of information supplied by Industrial Users, occasional and continuing noncompliance with Pretreatment Standards. Inspect and sample the effluent from each Significant Industrial User at least once a year." The standard to which POTWs are held for purposes of evidence collection during a Control Authority monitoring event is outlined in 40 C.F.R. 403.8(f)(2)(vii): "Sample taking and analysis and the collection of other information shall be performed with sufficient care to produce evidence which is admissible in enforcement proceedings or judicial actions." In addition, a POTW is required to ensure the Control Authority monitoring events are based on representative conditions at the monitoring point to ensure that these sampling events are legally defensible and of the same quality as required for self-monitoring events. The Pretreatment Regulations at 40 C.F.R. 403.12(g)(3) require, "The reports ... must be based upon data obtained through appropriate sampling and analysis performed during the period covered by the report, which data are representative of conditions occurring during the reporting period." An enforceable sample must be representative of the nature and character of the discharges during the reporting period and is required to be representative in composition to that in the larger volume of wastewater being discharged. A POTW is required to implement a Control Authority monitoring program that meets the compliance monitoring requirements of the Pretreatment Regulations, provides representative data for compliance determinations, and would be legally defensible in court if such an enforcement action is taken by the POTW. In addition, representative and legally defensible data helps the POTW support other program objectives such as local limits evaluation and permit development or reissuance. 10.2 Sampling Plan and Protocols As required in 40 C.F.R. 403.8(f)(2), the POTW shall "develop and implement procedures to ensure compliance with the requirements of a Pretreatment Program." The development and implementation of a sampling plan or procedures ensures the POTW is appropriately and consistently performing sampling or monitoring events, as well as providing enforceable data that is representative of the discharge conditions at the facility. The sampling plan should include the following: Purpose and objective of the sampling program, Specific sampling protocols at each facility sampling location to ensure representative sampling, and Appropriate QA/QC procedures to ensure legally defensible data. 10.2.1 Site-Specific Sampling Protocols The sampling protocols must include specific procedures used at each facility to ensure adequate and representative sampling protocols. The development of the sampling 56 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 protocols will ensure the sampling events are performed in accordance with appropriate standards and procedures and produce quality data that is legally defensible. At a minimum, the specific sampling protocols at each sampling location should include the following: Sampling locations - should include all monitoring points included in the SIU's permit, including the use of digital photos for each monitoring point. Type of sample - the POTW is required to ensure the sampling event is representative of the SIU's discharge, as required by 40 C.F.R. 403.12(g)(3). The type of sample will be dependent on the parameter to be sampled and discharge characteristics. The type of sample could include specifications for the use of automatic samplers (including programming to provide representative sampling) or manual sampling techniques. Type of Flow Measurement - if applicable Parameters for Analysis - based on the SIU's permit Sample Volume Type of Sample Containers Sample Preservation Techniques Sample Identification and Chain of Custody Procedures QA/QC Procedures 10.2.2 Quality Assurance/Quality Control (QA/QC) QA and QC are tools that are necessary in a sampling program to maintain a level of quality, such as legally defensible data, in the measurement, documentation, and interpretation of sampling data. The QA/QC procedures are used to obtain data that are both precise (degree of closeness between two or more samples) and accurate (degree of closeness between the results obtained from the sample analysis and the true value that should have been obtained). Proper implementation of QA/QC procedures will result in an increase in the POTW's confidence in the validity of the reported analytical data. The QA/QC procedures used to ensure data collected is valid and legally defensible include, but are not limited to, the following: Equipment maintenance/calibration, Proper sampling bottles, proper sampling techniques that are adequate and representative of the discharge from the facility, Field blanks, equipment blanks, method blanks, standards, blind duplicates, and ensuring sampling personnel are adequately trained. 10.3 The EPA Evaluation of the BOPU's Control Authority Monitoring 10.3.1 SOPs The BOPU has developed a general overview of sampling in its IPP Guidance that includes an overview of operation, use, and maintenance of automatic samplers. In addition, the 57 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 BOPU has develop annual compliance sampling that provides an overview of compliance sampling procedures in its IPP Guidance and sampling guides for each SIU. The BOPU is required to incorporate QA/QC procedures such as equipment blanks, trip blanks, sample duplicates, matrix spikes, and control standards to ensure the sampling and analytical techniques are in control and compliance with 40 C.F.R. 136. The EPA recommends the BOPU consolidate its SIU sampling procedures in SIU-specific sampling protocols to ensure consistent sampling that is representative for the production day. In addition, the EPA recommends the BOPU incorporate digital photos into the SIUspecific sampling protocols. 10.3.2 BOPU's Control Authority Monitoring Based on the EPA's review of the Pretreatment records, the BOPU samples the permitted SIUs at least once per year and meets the Control Authority monitoring frequency required in 40 C.F.R. 403.8(f)(2)(v). 11.0 Enforcement 11.1 Regulatory Background The EPA establishes the regulatory requirement to develop and implement an Enforcement Response Plan (ERP) in the Pretreatment Regulations at 40 C.F.R. 403.8(f)(5)(i-iv). The regulations state: "The POTW shall develop and implement an enforcement response plan. This plan shall contain detailed procedures indicating how a POTW will investigate and respond to instances of industrial user noncompliance. The plan shall, at a minimum: (i) Describe how the POTW will investigate instances of noncompliance. (ii) Describe the types of escalating enforcement responses the POTW will take in response to all anticipated types of industrial user violations and the time periods within which responses will take place. (iii) Identify (by title) the official(s) responsible for each type of response. (iv) Adequately reflect the POTW's primary responsibility to enforce all applicable pretreatment requirements and standards." The development and implementation of an ERP is an important component of an effective Pretreatment Program. Although a successful Pretreatment program should provide outreach to facilities in the service area regarding the applicability of the Pretreatment Standards and compliance with these standards, in many situations, enforcement is the necessary driving force that makes the Pretreatment program functional. The ERP establishes a framework for POTWs to formalize procedures for investigating and responding to instances of IU noncompliance and to ensure that POTWs enforce against IUs objectively, consistently, and equitably. A well-developed ERP should help the POTW decide what resources are needed to enforce the Pretreatment 58 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Standards/Requirements and assist in dealing with IU violations. In addition, the ERP will provide notice to the IUs regarding the POTW's responsibility to respond to violations of Pretreatment Standards/Requirements. 11.2 Enforcement Legal Authority The EPA evaluated the BOPU's enforcement authority and remedies found in its municipal ordinance. 1. Civil/Criminal penalties established in 13.20.760 and 13.20.770. 2. Injunctive relief provisions established in 13.20.750. 3. Authority to enforce against falsification/tampering established in 13.20.770(B). 4. Notice of violations authority established in 13.20.660. 5. Compliance orders authority established in 13.20.690, consent orders established in 13.20.670 and cease and desist orders established in 13.20.700. 6. Administrative penalty authority established in 13.20.710. 7. Show cause hearing provisions in 13.20.680. 8. Suspensions of service provisions in 13.20.720 and 13.20.730. 9. Permit termination provisions established in 13.20.740. 10. Publication of IUs in significant noncompliance in 13.20.550. 11.3 Enforcement Response Plan (ERP) The BOPU submitted its ERP to the EPA for review, prior to the audit. The EPA previously reviewed and approved the ERP on November 21, 2023. The BOPU's ERP complies with the Pretreatment Regulations found at 40 C.F.R. 403.8(f)(5)(i-iv). 11.4 Compliance Evaluation Based on the EPA's review of the Pretreatment records, it appears that the BOPU is consistently evaluating compliance in the self-monitoring reports or notices submitted by the SIUs and IUs in the POTW's service area. However, as mentioned previously, the BOPU needs to ensure it consistently files the reports, notices, and correspondence to ensure the Pretreatment record is current and complete. 11.5 SNC Calculations and Public Participation The Pretreatment Regulations at 40 C.F.R. 403.8(f)(2)(viii) require a POTW to comply with the public participation requirements in the enforcement of National Pretreatment Standards. These procedures shall include a provision for at least annual public notification in a newspaper of general circulation, that provides meaningful public notice within the jurisdictions served by the POTW. The annual public notification should include a list of IUs, that, at any time during the previous 12 months, were in SNC with applicable Pretreatment requirements. The SNC determinations are both a calculation of numeric Pretreatment Standards, as listed in 40 C.F.R. 403.8(f)(2)(viii)(A-D), and a determination of violations of the narrative Pretreatment Standards, as listed in 40 C.F.R. 403.8(f)(2)(viii)(E-H). 59 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Based on EPA's review of the Pretreatment records, the BOPU is calculating numeric SNC and determining narrative SNC as necessary per the Significant Noncompliance SOP developed by the BOPU. The EPA recommends the BOPU consistently document its SNC determination of the narrative SNC criteria, to implement section 4.d of the SNC SOP. If no SNC of numeric criteria is calculated during the quarter, then the SNC records should document this with a statement such as "no numeric SNC violations during this reporting period". Similarly, if no SNC of narrative criteria is determined, then the SNC records should document this with a statement such as "all narrative SNC criteria evaluated and no SNC during this reporting period". 12.0 Trucked and Hauled Waste 12.1 Regulatory Background In addition to receiving waste through the collection system, many POTWs accept trucked and hauled waste. As stated in 40 C.F.R. 403.1(b)(1), pollutants from nondomestic sources that are transported to the POTW by truck or rail are also subject to the Pretreatment Regulations. They may also be subject to the categorical Pretreatment Standards. Therefore, hauled wastes from CIUs or hauled waste that otherwise qualifies the discharger as an IU must be regulated in accordance with the requirements of the Pretreatment Regulations; this includes any applicable requirements for permitting and inspecting the generating facility. Hauled wastes, like wastes received through the collection system, have the potential to negatively affect the POTW, making regulatory control of the wastes necessary. Most wastewaters hauled or trucked to a POTW are domestic septage, typically from homes outside the POTW's service area, but compatible in nature. Because such discharges are predominantly compatible wastes, treatment at a POTW is the most appropriate disposal method. The biosolids regulations at 40 C.F.R. 503.9(f) define domestic septage as the liquid or solid material removed from a septic tank, cesspool, portable toilet, Type III marine sanitation device, or similar system that holds only domestic sewage. Domestic septage does not include liquid or solid material removed from any system that receives either commercial wastewater or industrial wastewater, and it does not include grease removed from a restaurant grease trap. The POTW cannot know for certain the nature and concentration of the trucked wastes and the impact on the POTW without implementing some type of control or surveillance program. Unlike discharges from IUs directly connected to the POTW, the makeup of a load of hauled waste is virtually unknown without some type of monitoring, be it visual or analytical. Even compatible loads of domestic septage can cause problems for a POTW due to high strength or discharge rate. Domestic septage can be partially digested, higher in metals concentrations than normal domestic wastes, or contain small amounts of household contaminants (e.g., cleaners). Similarly, disinfectants used in portable toilets have the potential to affect POTW operations. Receipt of hauled hazardous waste (as defined in the Resource Conservation and Recovery Act (RCRA)) might not only affect POTW operations but also could subject the POTW to additional reporting requirements. The Domestic Sewage Exclusion, specified in 40 C.F.R. 60 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025  261.4(a)(1)(ii), provides that hazardous wastes mixed with domestic sewage and under control of the Pretreatment program are exempt from the RCRA waste regulations. However, hazardous wastes received by truck or rail (or dedicated pipe) at the treatment plant are not exempt from the regulations. POTWs that accept hazardous wastes from those sources are subject to permit by rule status under RCRA [40 C.F.R. 270.60(c)] provided that certain requirements are met. The POTW must be in compliance with all its NPDES permit requirements and the waste must comply with all federal, state, and local pretreatment requirements. 12.2 Legal Authority The BOPU has adopted the Federal specific discharge prohibitions for trucked and hauled wastes found in the Pretreatment Regulations at 40 C.F.R. 403.5(b)(8). This is incorporated by the BOPU in section 13.20.050(B)(9) of its municipal ordinance: "Any trucked or hauled pollutants, except at discharge points designated by the BOPU." In addition, the BOPU has established trucked and hauled waste recordkeeping and reporting requirements for companies servicing grease interceptors from food service establishments in section 13.20.545(B)(8)(m), and listed below: "Each industrial user that is required to use and maintain a grease interceptor, at their expense, shall keep a record of every time the grease interceptor is pumped, cleaned, or repaired. All methods of record keeping shall be approved by the BOPU. Methods may include: manifests for grease disposal, grease interceptor self-cleaning logs, and reporting software programs. This record shall include, unless otherwise approved by the BOPU, at a minimum, the establishment name, address, phone number, the date and time of pumping and cleaning, the name of the company that is performing the pumping and cleaning of the grease interceptor, the amount of waste removed, certification statements provided in this subparagraph, below, for both the establishment and the company performing the cleaning and hauling of the grease interceptor, the printed name and signature of the responsible party for both the generator (establishment) and the transporter (company cleaning grease interceptor and hauling the waste). These records shall be submitted to the BOPU within two weeks of the grease interceptor cleaning, or as specified by the BOPU. All records for grease interceptor cleaning or repairs shall be kept on the premises for at least three years and be available to the BOPU upon request. The removed contents from any grease interceptor shall be handled by a person licensed to haul such waste and shall be disposed of in accordance with federal, state, and local regulations. A grease interceptor located inside the facility may be cleaned by the establishment's employees upon approval by the BOPU provided BMPs are followed, a log approved by the BOPU is kept and submitted to the BOPU within two weeks of each cleaning or as specified by the BOPU, and the waste is disposed of in accordance with federal, state, and local regulations." Certification Statement for Establishment: "I acknowledge that, as the generator of grease interceptor waste, I am responsible for following the requirements of Chapters 13.12 and 13.20, of the Cheyenne City Code and 61 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 that failure to do so may result in fines and penalties. To the best of my knowledge, the grease interceptor cleaning service has been properly performed." Certification Statement for Company performing Cleaning and Hauling: "I certify that I have cleaned the above grease interceptor in accordance with Chapters 13.12 and 13.20 of the Cheyenne City Code. To the best of my knowledge, the waste being transported and disposed of contains no hazardous material." 12.3 Trucked and Hauled Waste Disposal Location and Control Mechanisms 12.3.1 Crow Creek POTW The BOPU accepts oily water and sand generated from municipal activities and maintenance of its collection and stormwater systems. The municipal-generated trucked waste is accepted at the Crow Creek POTW drying beds, as shown in Figure 3. The trucked waste is allowed to dry for period of time, liquids may be decanted, and the solidified wastes are mixed with kiln dust and transported to a landfill for disposal. According to BOPU representatives, there is no discharge of liquids from this waste to the Crow Creek POTW. 12.3.2 Dry Creek POTW The BOPU accepts septage, grease and stormwater trucked waste at the disposal station at the Dry Creek POTW, as shown in Figures 6-9. The hauled waste disposal station is open for disposal 24/7 and is equipped with cameras. The disposal station is tied directly into the Crow Creek interceptor line that flows into the Dry Creek POTW headworks wet well The hauled waste companies must gather approval by the County Health Department and get set up by the City's Accounting department. The volume of the hauled waste truck is verified by the BOPU and have current insurance and Safety Data Sheets for chemical usage. The approved hauler truck must stop at the Operations Laboratory and drop off a hauled waste sample and waste manifests before use of the disposal station. Based on the EPA's evaluation of the septic disposal site and available records, it appears that the BOPU has adequate control of trucked and hauled waste in the service area. 62 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Figure 7 - Dry Creek POTW Septic Disposal Station Figure 8 - Dry Creek POTW Septic Disposal Station Sign 63 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Figure 9 - Dry Creek POTW Septic Disposal Station - Septic Truck Discharge 12.3.3 RV Disposal Stations According to information gathered during the audit, the BOPU has four RV disposal sites within the service area: Southeast Wyoming Travel Center, 5611 High Plains Road, Cheyenne, WY 82007 Maverik Adventure's First Stop, 1706 S Greeley Hwy, Cheyenne WY 82007 Love's, 3305 W College Drive, Cheyenne, WY 82007 Pilot/Flying J, 2250 Etchepare Drive, Cheyenne, WY 82007 The EPA recommends the BOPU evaluate appropriate control and site access to ensure these sites only accept RV waste and are not illicitly used for non-RV waste. Low cost control options may include locked disposal site with access available upon signing into a logbook to record activities. The BOPU may require reporting of these records or ensure these are available upon inspection. 13.0 Best Management Practices - Sector Control Programs 13.1 Regulatory Background BMPs are defined in 40 C.F.R. 403.3(e) as "schedules of activities, prohibitions of practices, maintenance procedures, and other management practices to implement the prohibitions listed in 40 C.F.R. 403.5(a)(1) [General Prohibitions] and (b) [Specific Prohibitions]. BMPs also include treatment requirements, operating procedures, and 64 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 practices to control plant site runoff, spillage or leaks, sludge or waste disposal, or drainage from raw materials storage." 40 C.F.R. 403.5(c)(4) states, "POTWs may develop Best Management Practices (BMPs) to implement paragraphs (c)(1) [develop limits to implement the general/specific prohibitions] and (c)(2) [develop and enforce specific effluent limits for industrial users that contribute pollutants that may result in Interference and Pass-Through] of this section. Such BMPs shall be considered local limits and Pretreatment Standards for the purposes of this part and section 307(d) of the Act." The regulations establish that BMPs are enforceable Pretreatment Standards. 13.2 Authority in Rules and Regulations The BOPU established the authority to implement BMPs in its Rules and Regulations as follows: BMP definition and established as Pretreatment Standards in 13.20.030. BMPs established as a permit condition in 13.20.280(A)(3). BMP recordkeeping requirements referenced in 13.20.520. BMPs established as an SNC criterion in 13.20.550(A)(8). The BOPU has established specific sector control programs, based on BMPs for industrial users to control specific pollutants as necessary in 13.20.545. o BMPs for FOG facilities in 13.20.545(B). o BMPs for Sand Interceptor and Oil Water Separator Requirements in 13.20.545(C). 13.3 Dental Amalgam BMP Sector Control Program The Dental Amalgam Rule, found in 40 C.F.R. Part 441, was promulgated as a final rule with new source dental facilities required to be in compliance with the Pretreatment Standards as of July 14, 2017, and existing source dental facilities required to be in compliance as of June 14, 2020. Compliance with the rule requires the installation of an ISO1143 amalgam separator or equivalent device, and compliance with the following two BMPs: Prohibition on the use of oxidizing or chlorine-containing line cleaners; and Ensuring all amalgam process wastewater including chair-side traps, screens, vacuum pump filters, dental tools, cuspidors or collection devices are treated through the amalgam separator. In addition, the new and existing dental facilities are required in 40 C.F.R. 441.50 of the Dental Amalgam Rule to provide a report that characterizes the dental facility and certifies compliance. The new source dental facilities are required to be in compliance upon discharge and submit a one-time compliance report within 90 days of startup. The BOPU has identified 43 dental facilities in its service area and has received one-time compliance reports within the deadline required by the Rule. The EPA reviewed the onetime compliance reports to ensure compliance with the reporting requirements of the 65 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 Dental Amalgam Rule in 40 C.F.R. 441.50. The following compliance reports are not complete. The BOPU is required to follow up with the following dental offices to ensure the dental facilities comply with the Dental Amalgam Rule: (Note: most reports are not date stamped by the BOPU): The Smile Academy (Children's Dentistry) Dana Barnes Jerri Donahue Gentle Touch Kincheloe and Tonso Mark D Rinne 13.4 FOG Sector Control Program The BOPU has established sector control requirements for the food service establishments (FSE) with grease interceptors and IUs with sand interceptors in the service area to control fats, oils, and greases (FOG). The sector control BMPs require installation and maintenance of appropriate technology such as, gravity grease interceptors for FOG and sand or oil/water interceptor for facilities that have the potential to discharge petroleum oil, mineral oil, cutting oils, non-food grease and solids. The sector control BMPs include appropriate maintenance, recordkeeping and reporting requirements for the operation of the interceptors. The BOPU has about 400 IUs with grease or sand interceptors in the POTW's service area. The BOPU requires FSEs to report the records within 14 days of the cleaning event. The cleaning frequency is based on performance and is determined in a 30/90/180/360-day frequencies, but the default frequency for new FSEs is 90-days. 14.0 PFAS Roadmap and Implementation Harmful per- and poly-fluoroalkyl substances (PFAS) are an urgent public health and environmental issue facing communities across the United States. PFAS have been manufactured and used in a variety of industries in the United States and around the globe since the 1940s, and they are still being used today. Because of the duration and breadth of use, PFAS can be found in surface water, groundwater, soil, and air--from remote rural areas to densely populated urban centers. A growing body of scientific evidence shows that exposure at certain levels to specific PFAS can adversely impact human health and other living things. Despite these concerns, PFAS are still used in a wide range of consumer products and industrial applications. Every level of government--federal, tribal, state, and local--needs to exercise increased and sustained leadership to accelerate progress to clean up PFAS contamination, prevent new contamination, and make game-changing breakthroughs in the scientific understanding of PFAS. 14.1 2021 EPA PFAS Strategic Roadmap On October 18, 2021, the EPA developed the Agency's PFAS Strategic Roadmap -- laying out a whole-of-agency approach to addressing PFAS. The roadmap sets timelines 66 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 by which EPA plans to take specific actions and commits to policies designed to safeguard public health, protect the environment, and hold polluters accountable. The PFAS Strategic Roadmap may be found at the following link: https://www.epa.gov/pfas/pfas-strategicroadmap-epas-commitments-action-2021-2024 . The EPA's integrated approach to PFAS is focuses on three central directives: 1. Research. Invest in research, development, and innovation to increase understanding of PFAS exposures and toxicities, human health and ecological effects, and effective interventions that incorporate the best available science. 2. Restrict. Pursue a comprehensive approach to proactively prevent PFAS from entering air, land, and water at levels that can adversely impact human health and the environment. 3. Remediate. Broaden and accelerate the cleanup of PFAS contamination to protect human health and ecological systems. The EPA's approach is shaped by the unique challenges to addressing PFAS contamination. The EPA cannot solve the problem of "forever chemicals" by tackling one route of exposure or one use at a time. Rather, the EPA understands that it needs to take a lifecycle approach to PFAS to make meaningful progress. PFAS pollution is not a legacy issue--these chemicals remain in use in U.S. commerce. The risks posed by PFAS demand that the Agency attack the problem on multiple fronts at the same time. In the 2021 PFAS Roadmap, the EPA is leveraging the full range of statutory authorities to confront the human health and ecological risks of PFAS: Water - Clean Water Act (CWA) Solid Waste - Resource Conservation and Recovery Act (RCRA) Land - Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Air - Clean Air Act (CAA) Chemical Safety and Pollution Prevention - Toxic Substances Control Act (TSCA) For purposes of this audit, the EPA is addressing the initiatives used in the Office of Water under the Safe Drinking Water Act, the Clean Water Act, the NPDES Permitting program and associated programs under the NPDES regulatory umbrella. The specific PFAS Roadmap commitments and updates may be found at the following link: https://www.epa.gov/pfas/pfas-strategic-roadmap-epas-commitments-action-20212024#ow . 14.2 Leverage NPDES permitting to reduce PFAS discharges to waterways The National Pollutant Discharge Elimination System (NPDES) program interfaces with many pathways by which PFAS travel and are released into the environment and ultimately impact people and water quality. 67 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025 On December 5, 2022, the EPA issued the Addressing PFAS Discharges in NPDES Permits and Through the Pretreatment Program and Monitoring Programs Memo to the U.S. States to proactively use existing NPDES authorities to reduce discharges of PFAS at the source and obtain more comprehensive information through monitoring on the sources of PFAS and the quantity of PFAS discharged by these sources. This memorandum provides the EPA's guidance to states and updates the April 28, 2022 guidance to the EPA Regions for addressing PFAS discharges when they are authorized to administer the NPDES permitting program or Pretreatment program. The memo provides the following recommendations for POTW NPDES permits and Pretreatment programs: POTW NPDES Permits: o Quarterly effluent, influent and biosolids monitoring using EPA Method 1633. o Recommended biosolids assessment, based on biosolids monitoring and a PFAS source reduction for IUs in the POTW's service area, if necessary. o Public notice of downstream drinking systems that are potentially affected by the POTW effluent when the POTW's NPDES permit is renewed or issued. Pretreatment Programs: o Source Identification: Update IU inventory to include PFAS sources o Source Control: Utilize BMPS and pollution prevention to address PFAS discharges to the POTW; Update IU permits to required quarterly PFAS monitoring. Develop IU BMPS or local limits for PFAS, where authority exists through the NPDES permit limits or PFAS ELG promulgation. 14.3 Impact of the NPDES Initiatives on the BOPU's Pretreatment Program The analytical tools, rules, procedures, and methods developed by the EPA in the PFAS Strategic Roadmap are currently recommendations to identify and control non-domestic or IU sources in a POTW's service area. The requirement to control IUs will occur either when the EPA promulgates categorical Pretreatment Standards for specific IU sectors (such as OCPSF, Metal Finishers or other future rulemakings), or when the NPDES State adopts the EPA National Water Quality Criteria for PFAS and PFOS as State water quality standards and begins implementing these as NPDES permit limits. However, EPA recommends the BOPU evaluate these recommendations and determine proactive measures to identify non-domestic sources of PFAS in its service area, and determine appropriate levels of control or compliance assistance. 68 Cheyenne Board of Public Utilities Pretreatment Audit Report WY-0022934 and WY-0022381 March 10, 2025, to March 13, 2025