Section NR 211.13 - Removal credits(1)(a) Any POTW receiving wastes from an industrial user to which a categorical pretreatment standard applies may, subject to the conditions of this section, grant removal credits for removal by the POTW of pollutants specified in the categorical pretreatment standard. The POTW may grant a removal credit equal to or less than its consistent removal rate. Upon being granted a removal credit, each affected industrial user shall calculate its revised discharge limits in accordance with par. (c).(b) A POTW may give removal credits only if: 1. The POTW applies for and receives authorization from the department to give a removal credit in accordance with the requirements and procedures specified in sub. (5). Removal credits may only be given for indicator or surrogate pollutants regulated in a categorical pretreatment standard if the categorical pretreatment standard so specifies.2. The POTW demonstrates and continues to achieve consistent removal of the pollutant in accordance with sub. (2).3. Except as provided in sub. (7), the POTW has an approved pretreatment program as required by this chapter; however, a POTW which does not have an approved pretreatment program may, pending approval of such a program, conditionally give credits as provided in sub. (4).4. The granting of removal credits will not cause the POTW to violate the local, state and federal sludge requirements which apply to the sludge management method chosen by the POTW. Alternatively, the POTW can demonstrate to the department that even though it is not presently in compliance with applicable sludge requirements, it will be in compliance when the industrial user to whom the removal credit would apply is required to meet its modified categorical pretreatment standard.5. The granting of removal credits will not cause a violation of the POTW's permit limitations or conditions. Alternatively, the POTW can demonstrate to the department that even though it is not presently in compliance with applicable limitations and conditions in its WPDES permit, it will be in compliance when the industrial user to whom the removal credit would apply is required to meet its modified categorical pretreatment standard.6. The granting of removal credits will not result in a discharge of pollutants to waters of the state greater than the discharge that would be allowed if the pollutants were discharged other than through a POTW.(c) Revised discharge limits for a specific pollutant shall be derived by use of the following formula: where:
x = pollutant discharge limit specified in the applicable categorical pretreatment standard.
r = removal credit for that pollutant as established under sub. (2) (percentage removal expressed as a proportion, i.e., a number between 0 and 1).
y = revised discharge limit for the specified pollutant (expressed in same units as x).
(2) DEMONSTRATION OF CONSISTENT REMOVAL. In order to demonstrate consistent removal, the POTW shall, for each pollutant [for] which removal credit authorization is sought, collect influent and effluent data and calculate consistent removal in accordance with the following requirements: (a) At least 12 representative samples of influent and effluent shall be taken at approximately equal intervals throughout one full year. Sampling shall be evenly distributed over the days of the week to include non-work days as well as work days. Upon concurrence of the department, a POTW may utilize a historical data base either in lieu of or as a supplement to these 12 samples. In order to be approved, the historical data base shall represent the yearly and seasonal conditions to which the POTW is subject and the POTW's performance for at least one year. Alternatively, a POTW, upon approval of the department, may utilize an alternative sampling design, if the samples to be taken represent the POTW's normal operating conditions and the different seasonal conditions to which the POTW is subject.(b) The POTW shall use the composite sampling method unless the grab sampling method is more appropriate. 1. Composite method. a. Influent and effluent operational data should be obtained through 24-hour flow proportional composite samples. Sampling may be done manually or automatically, and discretely or continuously. If discrete sampling is employed, at least 12 aliquots shall be composited. Discrete sampling may be flow proportioned either by varying the time interval between each aliquot or the volume of each aliquot. All composites shall be flow proportional to either the stream flow at the time of collection of the influent aliquot or to the total influent flow since the previous influent aliquot. Volatile pollutant aliquots shall be combined in the laboratory immediately before analysis.b. Effluent sample collection need not be delayed to compensate for hydraulic detention. However, the POTW may elect to include detention time compensation or the department may require detention time compensation. The department may require that each effluent sample is taken approximately one detention time later than the corresponding influent sample if necessary to represent actual POTW operation. The detention period shall be based on a 24-hour average daily flow value. The average daily flow shall be based on the average of the daily flows during the same month of the previous year.2. Grab method. If composite sampling is not an appropriate technique, grab samples shall be taken to obtain influent and effluent operational data. A grab sample is an individual sample collected over a period of time not exceeding 15 minutes. The collection of influent grab samples shall precede the collection of effluent samples by approximately one detention period except that where the detention period is greater than 24 hours such staggering of the sample collection may not be necessary or appropriate. The detention period shall be based on a 24-hour average daily flow value. The average daily flow shall be based upon the average of the daily flows during the same month of the previous year. Grab sampling shall be employed where the pollutants being evaluated are those which may not be held for an extended period because of biological, chemical or physical interaction after sample collection which affects the results. Note: Examples: Cyanide and phenol.
(c) The POTW shall analyze the samples for pollutants in accordance with the analytical techniques prescribed in ch. NR 219. If ch. NR 219 does not contain analytical techniques for the pollutant in question, or if the department determines that ch. NR 219 analytical techniques are inappropriate, the analysis shall be performed using validated analytical methods or any other applicable analytical procedures approved by the department including procedures suggested by the POTW.(d)1. For purposes of this paragraph "measurable" refers to the ability of the analytical method to quantify as well as identify the presence of the pollutant in question. "Limit of detectability" refers to the lowest limit at which the analytical method can quantify the pollutant in question.2. For each sample, removal shall be calculated by dividing the difference between the concentrations of a pollutant in the POTW's influent and effluent by the influent concentration. If the number of samples with measurable concentrations is greater than 12, the consistent removal is the average of the lowest half of the removals. If the number of samples with measurable concentrations is between 8 and 12, the consistent removal is the average of the lowest 6 removals. If less than 8 samples have measurable concentrations, the department may approve a means for demonstrating consistent removal on a case-by-case basis.3. If a substance is measurable in the influent but not in the effluent, the effluent concentration may be assumed to be the limit of measurement, and those data may be used by the POTW, subject to approval by the department.4. When calculating consistent removal, the POTW shall use all of the data obtained for measuring removal, except for measurements in which a substance is not measurable in the influent.(e) If an overflow of untreated water to receiving water occurs at least once per year, a POTW may claim consistent removal only by complying with either subd. 1. or 2., except as provided in subd. 3. 1. The POTW shows, to the department's satisfaction, that:a. All industrial users to which the POTW proposes to apply removal credits have demonstrated the ability to contain or reduce discharges or increase pretreatment to compensate for the removal not being provided by the POTW during circumstances in which overflow can be reasonably expected to occur;b. The POTW has identified circumstances in which an overflow event can be reasonably expected to occur and has a notification plan or other viable plan to ensure that industrial users will learn of an impending overflow event in sufficient time to contain or reduce discharges or increase pretreatment to prevent untreated overflow from occurring;c. The POTW will monitor and verify the data required in subd. 1. d. to ensure that industrial users are containing or reducing discharges or pretreatment during overflow events; andd. All industrial users to which the POTW proposes to apply removal credits have demonstrated the ability and commitment to collect and make available, upon request, to the POTW, department or EPA, daily flow reports or other data sufficient to demonstrate that all discharges from regulated processes containing the pollutant for which the removal credit is requested were contained, reduced or subject to increased pretreatment during all circumstances in which an overflow was reasonably expected to occur.2.a. The consistent removal calculated according to par. (d) is reduced according to the following equation: Where:
rc = corrected removal
rm = POTW' s consistent removal for that pollutant as established by sub. (1)
Z = hours per year that overflow occurred between the industrial user and the POTW treatment plant, as shown in the POTW' s current WPDES permit application or by verifiable data specifically related to overflows between a particular industrial user and the POTW treatment plant; and
b. The POTW is complying with all WPDES permit requirements and any additional requirements in any order or decree issued pursuant to the Federal Water Pollution Control Act, (33 U.S. Code section 1251 et seq.), (Clean Water Act), affecting combined sewer outflows. These requirements include, but are not limited to, any requirements contained in EPA's Combined Sewer Overflow Control Policy.3. This paragraph does not apply if the industrial user can show that overflow does not occur between the industrial user and the POTW treatment plant.(3) PROVISIONAL CREDITS. For pollutants which are not discharged currently (i.e., new or modified facilities, or production changes) the POTW may apply for authorization to give removal credits prior to the initial discharge of the pollutant. Consistent removal for the first 18 months of discharge shall be based on data from treatability studies or demonstrated removal at other treatment facilities where the quality and quantity of influent are similar. Eighteen months after initial discharge of pollutants, consistent removal shall be demonstrated pursuant to the requirements of sub. (2). If the POTW cannot demonstrate consistent removal pursuant to the requirements of sub. (2), the authority to grant provisional removal credits shall be terminated by the department. All industrial users to whom the revised discharge limits had been applied shall achieve compliance with the applicable categorical pretreatment standards within a reasonable time, not to exceed the period of time prescribed in the applicable categorical pretreatment standards, as may be specified by the department.(4) TERMS AND CONDITIONS FOR POTW GRANTING AND CONTINUING CONDITIONAL REMOVAL CREDITS. A POTW required to develop a local pretreatment program by s. NR 211.20 may give removal credits pending approval of the program under the following terms and conditions: (a) All industrial users who are currently subject to a categorical pretreatment standard and who apply for a conditional removal credit shall submit to the POTW the information required in s. NR 211.15(1) (a) to (h). However, new or modified industrial users shall only submit the information required by s. NR 211.15(1) (a) to (f), pertaining to the categorical pretreatment standard as modified by the removal credit. The industrial users shall indicate what additional technology, if any, will be needed to comply with the categorical pretreatment standard as modified by the removal credit;(b) The POTW shall have submitted to the department an application for pretreatment program approval meeting the requirements of subch. II in a timely manner, not to exceed the time limitation set forth in a compliance schedule for development of a pretreatment program included in the POTW's WPDES permit, but in no case later than July 1, 1983, where no permit deadline exists;(c) The POTW shall: 1. Compile and submit data demonstrating its consistent removal in accordance with sub. (2);2. Comply with the conditions specified in sub. (1) (b); and3. Submit a complete application for removal credit authority in accordance with sub. (5);(d) If a POTW receives authority to grant conditional removal credits and the department subsequently makes a final determination, after appropriate notice, that the POTW failed to comply with the conditions in pars. (b) and (c), the authority to grant conditional removal credits shall be terminated by the department. All industrial users to whom the revised discharge limits had been applied shall achieve compliance with the applicable categorical pretreatment standard within a reasonable time, not to exceed the period of time prescribed in the applicable categorical pretreatment standard, as may be specified by the department.(e) If a POTW grants conditional removal credits and the POTW or the department subsequently makes a final determination, after appropriate notice, that the industrial user failed to comply with the conditions in par. (a), the conditional credit shall be terminated by the POTW or the department for the non-complying industrial user. The industrial user to whom the revised discharge limits had been applied shall achieve compliance with the applicable categorical pretreatment standard within a reasonable time, not to exceed the period of time prescribed in the applicable categorical pretreatment standard, as may be specified by the department. The conditional credit may not be terminated where a violation of the provisions of this paragraph results from causes entirely outside of the control of the industrial user or the industrial user had demonstrated substantial compliance.(f) The department may decide not to review an application for conditional removal credit authority, in which case the conditionally revised discharge limits shall become effective and remain in effect until reviewed by the department. This review shall be conducted in accordance with the procedures of s. NR 211.30 before any pretreatment program approval or any WPDES permit reissuance pursuant to the pretreatment program approval.(5) POTW APPLICATION FOR AUTHORIZATION TO GIVE REMOVAL CREDITS. (a) Any POTW that wants to give removal credits or modify existing ones shall apply for authorization from the department. Such application may be submitted at any time and shall include the following information: 1. A list of pollutants for which removal credits are proposed;2. The data required pursuant to sub. (2);3. Proposed revised discharge limits for each affected subcategory of industrial users calculated in accordance with sub. (1) (c);4. A certification that the POTW has an approved local pretreatment program or qualifies for the exceptions to this requirement found in subs. (4) and (7);5. A specific description of the POTW's current methods of using or disposing of its sludge and a certification that the granting of removal credits will not cause a violation of the sludge requirements identified in sub. (1) (b) 4.;6. A certification that the granting of removal credits will not cause a violation of the POTW's WPDES permit limits and conditions as required in sub. (1) (b) 5.; and7. A demonstration that the granting of removal credits will be consistent with sub. (1) (b) 6. for each industrial user for whom removal credits are proposed.(b) The department shall review the POTW's application for authorization to give or modify removal credits in accordance with the procedures of s. NR 211.30 within 180 days from public notice of an application to complete review.(c) Nothing in these regulations precludes an industrial user or other interested party from assisting the POTW in preparing and presenting the information necessary to apply for authorization.(6) CONTINUATION AND WITHDRAWAL OF AUTHORIZATION.(a) A POTW authorized to grant removal credits for a pollutant regulated in a categorical pretreatment standard may extend that removal credit to the same pollutant when it is regulated in other categorical standards. If a POTW elects to extend removal credits to a new categorical standard, industrial subcategory, or one or more industrial users that were not granted removal credits, it shall notify the department. A POTW may extend removal credits if granting the removal credit will not cause the POTW to violate the sludge requirements identified in sub. (1) (b) 4., or its WPDES permit limits and conditions as required by sub. (1) (b) 5.(b) Removal credits shall be included in the authorized POTW's WPDES permit as soon as possible and shall become an enforceable requirement of the POTW's WPDES permit. The removal credits shall remain in effect for the term of the POTW's WPDES permit, provided the POTW maintains compliance with the conditions specified in par. (d).(c) A POTW authorized to give removal credits shall monitor and report on the POTW's removal capabilities. The reporting period shall be specified by the department and may not be less than once per year. A minimum of one sample per month during the reporting period is required, and all sampling data shall be in-cluded in the POTW's compliance report. As a condition of retaining removal credit authorization, the POTW's consistent removal shall continue to be equal to or greater than the removal credit.(d)1. Compliance with the conditions in sub. (1) (b) 3. to 5. may be reviewed by the department whenever it elects and shall, at the very least, be reviewed whenever the POTW's WPDES permit is reissued. If the department determines, on the basis of compliance monitoring reports or other information available to it, that the conditions specified in sub. (1) (b) 3. to 5. are not being met, the department shall withdraw the POTW's authority to grant removal credits or modify those credits in accordance with the procedures specified in subd. 3.2. If, during the term of the POTW's WPDES permit, the department determines that the POTW's consistent removal rate is consistently and substantially lower than the removal credit specified in the POTW's WPDES permit, the department shall either withdraw the POTW's authority to grant removal credits or modify those credits in accordance with the procedures specified in subd. 3.3. If the department tentatively determines that a POTW's authority to grant removal credits should be withdrawn or modified, the department shall notify the POTW of its determination and give the POTW a reasonable time to take corrective action. The period for corrective action may exceed 60 days only if the POTW or industrial users demonstrate that a longer period is reasonably necessary to undertake appropriate corrective action.4. If the department finds the corrective action insufficient, the department shall, in accordance with the procedures specified in s. NR 211.30, issue a public notice, provide a public comment period of at least 30 days and provide an opportunity for interested persons to request a public hearing. The mailing list for the public notice shall include, at a minimum, the POTW and industrial users to whom the revised discharge limits have been applied.5. If the department finally determines to withdraw or modify the POTW's authority to grant removal credits, the department shall provide notice of the determination to the POTW, all industrial users to whom the revised limits have been applied and each person who has requested individual notice. This notice shall include the basis for the determination. Notice of the final determination shall also be published in the same newspaper that published the notice of the tentative determination.6. Following the notice required by subd. 5., all industrial users to whom revised discharge limits have been applied shall be subject to the modified discharge limits or the limits prescribed in the applicable categorical pretreatment standard. Industrial users shall comply with these limits within a reasonable time, not to exceed the period of time prescribed in the applicable categorical pretreatment standard, as may be specified by the department.(7) Where the department has not required the POTW to develop a pretreatment program, the POTW may not be required to develop a pretreatment program as a precondition to obtaining authorization to give removal credits. The POTW shall, however, be required to comply with the other conditions of sub. (1) (b).Wis. Admin. Code Department of Natural Resources NR 211.13
Cr. Register, September, 1986, No. 369, eff. 10-1-86; cr. (1) (b) 6., (2) (e), (5) (a) 7., (6) (d) 4. to 6., am. (2) (a), (5) (a) 5. and 6., r. and recr. (2) (d) 2. to 4. and (6) (d) 3., Register, March, 1992, No. 435, eff. 4-1-92; CR 13-006: r. and recr. (2) (e) 2. b. Register January 2014 No. 697, eff. 2-1-14.