Wyoming Administrative Code
Agency 020 - Environmental Quality, Dept. of
Sub-Agency 0011 - Water Quality
Chapter 2 - DISCHARGES, PERMIT REGS
Appendix E - Additional Requirements Applicable to New and Existing Publicly owned Treatment Works (POTWs)

Current through September 21, 2024

(a) Application requirements for new and existing POTWs. POTWs shall provide the following information, in addition to that described in Section 5(a) (v), to the administrator, using the application form provided by the administrator.

(i) Name of State Management/River Basin and 12 digit hydrologic cataloging unit code.

(ii) Critical flow of the receiving surface waters of the state and total hardness of the receiving surface waters of the state at critical low flow.

(iii) The following POTWs shall provide to the administrator the results of whole effluent toxicity testing conducted in accordance with EPA approved methods:

(A) All POTWs with design influent flows equal to or greater than one million gallons per day; and

(B) All POTWs with approved pretreatment programs or POTWs required to develop a pretreatment program.

(iv) Effluent monitoring for specific parameters.

(A) All applicants must submit to the administrator effluent monitoring information for samples taken from each outfall through which effluent is discharged to surface waters of the state, except for CSOs. The administrator may allow applicants to submit sampling data for only one (1) outfall on a case-by-case basis, where the applicant has two (2) or more outfalls with substantially identical effluent. The administrator may also allow applicants to composite samples from one or more outfalls that discharge into the same mixing zone.

(B) Unless otherwise indicated, all applicants must sample and analyze for the pollutants listed in Table E1 of this Appendix.

(C) Unless otherwise indicated, all applicants with a design flow greater than or equal to 0.1 mgd must sample and analyze for the pollutants listed in Table E2 of this Appendix. Facilities are not required to sample and analyze for chlorine if they do not use chlorine for disinfection, do not use chlorine elsewhere in the treatment process, and have no reasonable potential to discharge chlorine in their effluent.

(D) The following applicants must sample and analyze for the pollutants listed in 40 CFR 122 Appendix J Table 2 and for any other pollutants for which state surface water quality standards have been established for the receiving waters:

(I) All POTWs with a design flow rate equal to or greater than one million gallons per day.

(II) All POTWs with approved pretreatment programs or POTWs required to develop a pretreatment program.

(III) Any other POTW as required by the administrator.

(E) Unless otherwise indicated, all applicants must provide data from a minimum of three (3) samples taken within four and one-half (4.5) year prior to the date of the permit application. Samples must be representative of seasonal variation in the discharge from each outfall. Existing data may be used, if available, in lieu of sampling done solely for the purpose of this application.

(F) All existing data for pollutants specified in this Appendix that is collected within four and one-half (4.5) years of the application must be included in the pollutant data summary submitted by the applicant. If, however, the applicant samples for a specific pollutant on a monthly or more frequent basis, it is only necessary, for such pollutant, to summarize all data collected within one (1) year of the application.

(G) Unless otherwise indicated, all applicants must collect samples of effluent and analyze such samples for pollutants in accordance with analytical methods approved and 40 CFR Part 136 unless an alternative is specified in the existing WYPDES permit. Grab samples must be used for pH, temperature, cyanide, total phenols, residual chlorine, oil and grease, and fecal coliform. For all other pollutants, 24-hour composite samples must be used. For a composite sample, only one analysis of the composite of aliquots is required.

(H) The effluent monitoring data provided must include at least the following information for each parameter.

(I) daily maximum discharge, expressed as concentration or mass, based upon actual sample values;

(II) daily average discharge for all samples, expressed as concentration or mass, and the number of samples used to obtain this value;

(III) The analytical method used; and

(IV) The practical quantitation limit for the analytical method used.

(I) Unless otherwise required by the administrator, metals must be reported as dissolved or total recoverable as applicable in accordance with Wyoming Water Quality Rules and Regulations Chapter 1.

(v) In addition to the POTWs listed in paragraph (a) (i) of this appendix, the division may require other POTWs to submit the results of toxicity tests with their permit applications, based on consideration of the following factors:

(A) The variability of the pollutants or pollutant parameters in the POTW effluent (based on chemical-specific information, the type of treatment facility, and types of industrial contributors);

(B) The dilution of the effluent in the receiving water (ratio of effluent flow to receiving surface waters of the state flow);

(C) Existing controls on point or nonpoint sources, including TMDL calculations for the waterbody segment and the relative contribution of the POTW;

(D) Receiving water characteristics, including possible or known water quality impairment, and whether the POTW discharges to waters designated as Class 1 in accordance with Wyoming Water Quality Rules and Regulations Chapter 1; or

(E) Other considerations (including but not limited to the history of toxic impact and compliance problems at the POTW), which the administrator determines could cause or contribute to adverse water quality impacts.

(vi) For POTWs required under paragraph (a) (i) or (a) (ii) of this appendix to conduct toxicity testing, POTWs shall use methods approved by the administrator.

(vii) Effluent monitoring for whole effluent toxicity.

(A) All applicants must provide an identification of any whole effluent toxicity tests conducted during the four and one half (4.5) years prior to the date of the application on any of the applicant's discharges or on any receiving water near the discharge.

(B) Where the POTW has two or more outfalls with substantially identical effluent discharging to the same receiving water segment, the administrator may allow applicants to submit whole effluent toxicity data for only one (1) outfall on a case-by-case basis. The administrator may also allow applicants to composite samples from one (1) or more outfalls that discharge into the same mixing zone.

(C) Each applicant required to perform whole effluent toxicity testing pursuant to paragraph (a) (i) of this Appendix must provide:

(I) Results of a minimum of four (4) quarterly tests for a year, from the year preceding the permit application; or

(II) Results from four tests performed at least annually in the four and one half (4.5) year period prior to the application, provided the results show no appreciable toxicity using a safety factor determined by the permitting authority.

(D) Applicants must conduct tests with multiple species (no less than two (2) species; e.g., fish invertebrate, plant) and test for acute or chronic toxicity, depending on the range of receiving water dilution. It is recommended that applicants conduct acute or chronic testing based on the following dilutions.

(I) Acute toxicity testing if the dilution of the effluent is greater than 1,000:1 at the edge of the mixing zone.

(II) Acute or chronic toxicity testing if the dilution of the effluent is between 100:1 and 1000:1 at the edge of the mixing zone. Acute testing may be more appropriate at the higher end and chronic testing may be more appropriate towards the lower end.

(III) Chronic testing if the dilution of the effluent is less than 100:1 at the edge of the mixing zone.

(E) Unless otherwise directed by the administrator, each applicant required to perform whole effluent toxicity testing pursuant to paragraph (a) (i) of this appendix must provide the number of chronic or acute whole effluent toxicity tests that have been conducted since the last permit reissuance.

(F) Applicants must provide the results using a form provided by the administrator, or test summaries if available and comprehensive, for each whole effluent toxicity test conducted pursuant to this appendix for which such information has not been reported previously to the administrator.

(G) For the purposes of these regulations whole effluent toxicity testing for must be conducted using methods approved under 40 CFR Part 136.

(H) For whole effluent toxicity data submitted to the administrator within four and one half (4.5) years prior to the date of the application applicants must provide the dates on which the data were submitted and a summary of the results, unless otherwise directed by the administrator.

(I) Each POTW required to perform whole effluent toxicity testing in accordance with these regulations must provide any information on the cause of toxicity and written details of any toxicity reduction evaluation conducted, if any whole effluent toxicity test conducted within the past four and one-half years revealed toxicity.

(viii) POTWs receiving Resource Conservation and Recovery Act (RCRA), Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), or RCRA Corrective Action wastes or wastes generated at another type of environmental cleanup or remediation site must provide the following information.

(A) If the POTW receives, or has been notified that it will receive, by truck, rail, or dedicated pipe any wastes that are regulated as RCRA hazardous wastes pursuant to 40 CFR Part 261, the applicant must report the following:

(I) The method by which the waste is received (i.e., whether by truck, rail, or dedicated pipe); and

(II) The hazardous waste number amount received annually of each hazardous waste.

(B) If the POTW receives, or has been notified that it will receive wastewaters that originate from remedial activities, including those undertaken pursuant to CERCLA and sections 3004(u) or 3008(h) of RCRA, the applicant must report the following:

(I) The identity and description of the site(s) or facility(ies) at which the wastewater originates.

(II) The identities of the wastewater's hazardous constituents, as listed in Appendix VIII of 40 CFR Part 261, if known.

(III) The extent of treatment, if any, the wastewater receives or will receive before entering the POTW.

(C) Applicants are exempt from the requirements of paragraph (e)(ii) of this Appendix if they receive no more than fifteen kilograms per month of hazardous wastes as specified in 40 CFR 261.30(d) and 261.33(e).

(ix) Each applicant with combined sewer systems must provide the following information.

(A) Combined sewer system information:

(I) System map. A map indicating the location of the following:

(1.) All combined sewer overflow (CSO) discharge points.

(2.) Sensitive use areas potentially affected by CSOs.

(3.) Waters supporting threatened or endangered species potentially affected by CSOs.

(II) System diagram. A diagram of the combined sewer collection system that includes:

(1.) The location of major sewer trunk lines, both combined and separate sanitary.

(2.) The locations of points where separate sanitary sewers feed into the combined sewer system.

(3.) In-line and off-line storage structures.

(4.) The locations of flow regulating devices.

( 5.) The location of pump stations.

(B) Information on combined sewer outfalls:

(I) Description of the outfall, including:

(1.) Outfall number.

(2.) State, county, and city or town in which outfall is located.

(3.) Latitude and longitude, to the nearest 15 seconds.

(4.) Distance from shore and depth below surface. (5.) Whether the applicant monitored any of the following in the past year for the CSO:

a. Rainfall.

b. CSO flow volume.

c. CSO pollutant concentrations.

d. Receiving water quality.

e. CSO frequency.

(6.) The number of storm events monitored in the last year.

(II) CSO events. The following information about CSO overflows from each outfall.

(1.) The number of events in the past year.

(2.) The average duration per event, if available.

(3.) The average volume per CSO event if available.

(4.) The minimum rainfall that caused a CSO event, if available, in the last year.

(III) Description of receiving waters. The following information about receiving water.

(1.) Name of the receiving water.

(2.) Name of watershed/stream system and the State watershed (12-digit) code (if known).

(IV) CSO operations. A description of any known water quality impacts on the receiving water caused by the CSO (e.g., permanent or intermittent beach closings, permanent or intermittent fish kills, fish advisories, other recreational loss, or exceedance of any applicable state water quality standard.

(x) Contractors. All applicants must provide the name, mailing address, telephone number, and responsibilities of all contractors responsible for any operational or maintenance aspects of the facility.

(b) A permit application shall not be considered complete if the administrator has waived application requirements under this Appendix or Section 5 of these regulations and the Regional Administrator of the EPA has disapproved the waiver. If a waiver request has been submitted to the Regional Administrator of the EPA more than 210 days prior to permit expiration and the Regional Administrator has not disapproved the waiver application 181 days prior to permit expiration, the permit application lacking the information subject to the waiver request shall be considered complete.

(c) Secondary treatment requirements. This part provides information on the level of effluent quality that shall be obtained through the application of secondary or equivalent treatment.

(i) Terms used in this appendix are defined as follows:

(A) 7-day average. The arithmetic mean of pollutant parameter values for samples collected in a period of seven (7) consecutive days.

(B) 30-day average. The arithmetic mean of pollutant parameter values of samples collected in a period of 30 consecutive days.

(C) BOD5. The five day measure of the pollutant parameter biochemical oxygen demand (BOD5).

(D) CBOD5. The five day measure of the pollutant parameter carbonaceous biochemical oxygen demand (CBOD5).

(E) Effluent concentrations consistently achievable through proper operation and maintenance.

(I) For a given pollutant parameter, the 95th percentile value for the 30-day average effluent quality achieved by a treatment works in a period of at least two years, excluding values attributable to upsets, bypasses, operational errors, or other unusual conditions; and,

(II) A 7-day average value equal to 1.5 times the value derived under paragraph (c) (i) (E) (I) of this appendix.

(F) Facilities eligible for treatment equivalent to secondary treatment. Treatment works shall be eligible for consideration for effluent limitations described for treatment equivalent to secondary treatment (133.105) if:

(I) The BOD5 and TSS effluent concentrations consistently achievable through proper operation and maintenance of the treatment works exceed the minimum level of effluent quality set forth in 133.02(a) and (b).

(II) A trickling filter or waste stabilization pond is used as the principal process; and,

(III) The treatment works provide significant biological treatment of municipal wastewater.

(G) Percent removal. A percentage expression of the removal efficiency across a treatment plan for a given pollutant parameter, as determined from the 30-day average values of the raw wastewater influent pollutant concentrations to the facility and the 30-day average values of the raw wastewater influent pollutant concentrations to the facility and the 30-day average values of the effluent pollutant concentrations for a given time period.

(H) Significant biological treatment. The use of an aerobic or anaerobic biological treatment process in a treatment works to consistently achieve a 30-day average of at least 65 percent removal of BOD5.

(I) TSS. The pollutant parameter total suspended solids.

(J) Significantly more stringent limitation means BOD5 and TSS limitations necessary to meet the percent removal requirements of at least 5 mg/l more stringent than the otherwise applicable concentration-based limitations (e.g., less than 25 mg/l in the case of the secondary treatment limits for BOD5 and TSS), or the percent removal limitations in paragraphs (c) (ii) and (c) (v) of this appendix, if such limits would, by themselves, force significant construction or other significant capital expenditure.

(ii) Secondary Treatment. The following paragraphs describe the minimum level of effluent quality attainable by secondary treatment in terms of the parameters BOD5, TSS, and pH. All requirements for each parameter shall be achieved except as provided for in paragraphs (c) (iii) and (c) (v) of this appendix.

(A) BOD5.

(I) The 30-day average shall not exceed 30 mg/l.

(II) The 7-day average shall not exceed 45 mg/l.

(III) The 30-day average percent removal shall not be less than 85 percent.

(IV) At the option of the administrator, in lieu of the parameter BOD5. and the levels of the effluent quality specified in paragraphs (c) (ii) (A) (I) (II) and (III) , the parameter C BOD5. may be substituted with the following levels of the CBOD5 effluent quality provided:

(1.) The 30-day average shall not exceed 25 mg/l.

(2.) The 7-day average shall not exceed 40 mg/l.

(3.) The 30-day average percent removal shall not be less than 85 percent.

(B) TSS.

(I) The 30-day average shall not exceed 30 mg/l.

(II) The 7-day average shall not exceed 45 mg/l

(III) The 30-day average percent removal shall not be less than 85 percent.

(C) pH. The effluent values for pH shall be maintained within the limits of 6.0 to 9.0 unless the publicly owned treatment works demonstrates that: (1) Inorganic chemicals are not added to the waste stream as part of the treatment process; and (2) contributions from industrial sources do not cause the pH of the effluent to be less than 6.0 or greater than 9.0.

(iii) Special considerations.

(A) Combined sewers. Treatment works subject to this part may not be capable of meeting the percentage removal requirements established under 102 (a) (3) and (b) (3) or 105 (a) (3) and (b) (3) during wet weather where the treatment works receive flows from combined sewers (i.e., sewers which are designed to transport both storm water and sanitary sewage). For such treatment works, the decision must be made on a case-by-case basis as to whether any attainable percentage removal level can be defined, and if so, what the level should be.

(B) Industrial waste. For certain industrial categories, the discharge to surface waters of the state of BOD5 and TSS permitted under Sections 301(b) (1) (A) (i), (b) (2) (E) or 306 of the CWA may be less stringent than the values given in paragraphs (c) (ii) (A) (I) and (IV) (i), (c) (ii) (B) (I), (c) (v) (A) (I), (c) (v) (B) (I) and (c) (v) (E) (I) (i) of this appendix. In cases when wastes would be introduced from such an industrial category into a publicly owned treatment works, the values for BOD5 and TSS in paragraphs (c) (ii) (A) (I) and (IV) (i), (c) (ii) (B) (I), (c) (v) (A) (I), (c) (v) (B) (I) and (c) (v) (E) (I) (i) of this appendix may be adjusted upwards provided that: (1) The permitted discharge of such pollutants attributable to the industrial category, would not be greater that which would be permitted under Sections 301(b) (1) (A) (i), (b) (2) (E) or 306 of the CWA if such industrial category were to discharge directly into the surface waters of the state, and (2) the flow or loading of such pollutants introduced by the industrial category exceeds 10 percent of the design flow or loading of the publicly owned treatment works. When such an adjustment is made, the values for BOD5 or TSS in paragraphs (c) (ii) (A) (II) and (IV) (ii), (c) (ii) (B) (II), (c) (v) (A) (II), (c) (v) (B) (II) and (c) (v) (E) (I) (ii) of this appendix. should be adjusted proportionately.

(C) Waste stabilization ponds. The administrator, may authorize adjusting the minimum levels of effluent quality set forth in paragraphs (c) (v) (B) (1), (2) and (3) of this appendix for treatment works subject to this part, to conform to the TSS concentrations achievable with waste stabilization ponds, provided that:

(I) Waste stabilization ponds are the principal process used for secondary treatment; and

(II) Operation and maintenance data indicate that the TSS values specified in paragraphs (c) (v) (B) (1), (2) and (3) of this appendix cannot be achieved. The term "TSS concentrations achievable with waste stabilization ponds" means a TSS value, determined by the administrator, which is equal to the effluent concentration achieved 90 percent of the time within a state or appropriate contiguous geographical area by waste stabilization ponds that are achieving the levels of effluent quality for BOD5 specified in paragraphs (c) (v) (A) (1) of this appendix.

(D) Less concentrated influent wastewater for separate sewers. The administrator may authorize substituting either a lower percent removal requirement or a mass loading limit for the percent removal requirements set forth in paragraphs (c) (ii) (A) (III) and (IV) (iii), (c) (ii) (B) (III), (c) (v) (A) (III), (c) (v) (B) (III) and (c) (v) (E) (I) (iii) of this appendix provided that the permittee satisfactorily demonstrates that:

(I) The treatment works is consistently meeting, or will consistently meet, its permit effluent concentration limits but its percent removal requirements cannot be met due to less concentrated influent wastewater;

(II) To meet the percent removal requirements, the treatment works would have to achieve significantly more stringent limitations than would otherwise be required by the concentration-based standards; and

(III) The less concentrated influent wastewater is not the result of excessive I/I. The determination of whether the less concentrated I/I will use the definition of excessive I/I in 40 CFR 35.2005(b) (16) plus the additional criterion that inflow is non-excessive if the total flow to the POTW (i.e., wastewater plus inflow plus infiltration) is less than 25 gallons per capita per day.

(E) Less concentrated influent wastewater for combined sewers during dry weather. The administrator may substitute either a lower percent removal requirement or a mass loading limit for the percent removal requirements set forth in paragraphs (c) (ii) (A) (III) and (IV) (iii), (c) (ii) (B) (III), (c) (v) (A) (III), (c) (v) (B) (III) and (c) (v) (E) (I) (iii) of this appendix provided that the permittee satisfactorily demonstrates that:

(I) The treatment works is consistently meeting, or will consistently meet, its permit effluent concentration limits, but the percent removal requirements cannot be met due to less concentrated influent wastewater;

(II) To meet the percent removal requirements, the treatment works would have to achieve significantly more stringent effluent concentrations than would otherwise be required by the concentration-based standards; and

(III) The less concentrated influent wastewater does not result from either excessive infiltrations or clear water industrial discharges during dry weather periods. The determination of whether the less concentrated wastewater results from excessive infiltration is discussed in 40 CFR 352005(b) (28), plus the additional criterion that either 40 gallons per capita per day or 1500 gallons per inch diameter per mile of sewer may be used as the threshold value for that portion of the dry weather base flow attributed to infiltration. If the less concentrated influent wastewater is the result of clear water industrial discharges, then the treatment works must control such discharges pursuant to 40 CFR Part 403.

(iv) Sampling and test procedures.

(A) Sampling and test procedures for pollutants listed in this part shall be in accordance with guidelines in 40 CFR Part 136.

(B) Chemical oxygen demand (COD) or total organic carbon (TOC) may be substituted for BOD5 when a long-term BOD5 , COD or BOD5 TOC correlation has been demonstrated.

(v) Treatment equivalent to secondary treatment. This section describes the minimum level of effluent quality attainable by facilities eligible for treatment equivalent to secondary treatment under paragraph (c) (i) (F) of this appendix in terms of the parameters BOD5 , TSS and pH. All requirements for the specified parameters in paragraphs (c) (v) (A), (B) and (C) of this appendix shall be achieved except as provided for in paragraph (c) (iii), or paragraphs (c) (v) (D), (E) or (F) of this appendix.

(A) BOD5.

(I) The 30-day average shall not exceed 45 mg/l.

(II) The 7-day average shall not exceed 65 mg/l.

(III) The 30-day average percent removal shall not be less than 65 percent.

(B) TSS. Except where TSS values have been adjusted in accordance with paragraph (c) (iii) (C) of this appendix:

(I) The 30-day average shall not exceed 45 mg/l.

(II) The 7-day average shall not exceed 65 mg/l.

(III) The 30-day average percent removal shall not be less than 65 percent.

(C) pH. The requirements of paragraph (c) (ii) (C) of this appendix shall be met.

(D) Alternative requirements. Except as limited by paragraph (c) (v) (F) of this appendix, and after public notice and opportunity for public comment, the administrator may adjust the minimum levels of effluent quality set forth in paragraphs (c) (v) (A) (I), (A) (II), (B) (I) and (B) (II) of this appendix for trickling filter facilities and in paragraphs (c) (v) (A) (I) and (A) (II) of this section for waste stabilization pond facilities, to conform to the BOD5 and TSS effluent concentrations consistently achievable through proper operation and maintenance by the median (50th percentile) facility in a representative sample of facilities within the state or an appropriate contiguous geographical area that meet the definition of facilities eligible for treatment equivalent to secondary treatment.

(E) CBOD5 limitations.

(I) Where data are available to establish CBOD5 limitations for a treatment works subject to this Section, the administrator may substitute the parameter CBOD5 for the parameter BOD5. In paragraph (c) (v) (A) (I) (II) (III) of this appendix, on a case-by-case basis provided that the levels of CBOD5 effluent quality are not less stringent than the following:

(1.) The 30-day average shall not exceed 40 mg/l.

(2.) The 7-day average shall not exceed 60 mg/l.

(3.) The 30-day average percent removal shall not be less than 65 percent.

(II) Where data are available, the parameter CBOD5 may be used for effluent quality limitations established under paragraph (c) (v) (D) of this appendix. Where concurrent BOD5 effluent data are available, they must be submitted with the CBOD5 data as part of the approval process outlined in paragraph (c) (v) (D) of this appendix.

(F) Permit adjustments. Any permit adjustment made pursuant to this part may not be any less stringent than the limitations required pursuant to paragraph (c) (v) (A) through (E) of this appendix. Furthermore, more stringent limitations shall be required when adjusting permits if:

(I) For existing facilities, the administrator determines that the 30-day average and 7-day average BOD5 and TSS effluent values that could be achievable through proper operation and maintenance of the treatment works, based on an analyses of the past performance of the treatment works to achieve more stringent limitations, or

(II) For new facilities, the administrator determines that the 30-day average and 7-day average BOD5 and TSS effluent values that could be achievable through proper operation and maintenance of the treatment works, considering the design capability of the treatment process and geographical and climatic conditions, would enable the treatment works to achieve more stringent limitations.

(d) Permits for publicly owned treatment works will require that the permittee must provide adequate notification to the administrator of the following:

(i) Any new introduction of pollutants into the publicly owned treatment works from an indirect discharger which would be subject to Sections 301 or 306 of the CWA if it were directly discharging those pollutants, and

(li) Any substantial change in the volume or character of pollutants being introduced into that publicly owned treatment works by a source introducing pollutants into the publicly owned treatment works at the time of issuance of the permit.

(lii) For the purposes of Appendix E (d) (i) and (ii), adequate notification shall include information on the quality and quantity of effluent introduced into the publicly owned treatment works; and any anticipated impact of the change on the quantity or quality of effluent to be discharged from the publicly owned treatment works.