Section 327 IAC 5-2-11.6 - Great Lakes system dischargers establishment of water quality-based effluent limitations (WQBELs)Authority: IC 13-14-8; IC 13-14-9; IC 13-15-1-2; IC 13-15-2-1; IC 13-18-3
Affected: IC 13-11-2; IC 13-18-4
Sec. 11.6.
(a) The NPDES permit shall include conditions necessary to achieve water quality standards established under 327 IAC 2-1.5, including narrative water quality criteria. The numeric water quality criteria set forth in 327 IAC 2-1.5-8 and 327 IAC 2-1.5-16 and Tier I criteria and Tier II values established under 327 IAC 2-1.5-11 through 327 IAC 2-1.5-16 shall not be enforceable against any point source discharger until translated into effluent limitations that are incorporated in NPDES permits in accordance with this article.(b) TMDLs and WLAs developed under section 11.4 of this rule shall provide the basis for numeric water quality-based effluent limitations (WQBELs) established in NPDES permits for point sources discharging to waters within the Great Lakes system. If a variance has been granted from a water quality criterion under 327 IAC 2-1.5-17 and 327 IAC 5-3-4.1, WQBELs for the pollutant that is the subject of the variance shall be calculated on the basis of the variance rather than the water quality criterion.(c) The following procedure shall be used to calculate WQBELs using the WLAs developed under section 11.4 of this rule: (1) This subsection assumes that effluent data follow a log-normal distribution. If a discharger is able to demonstrate that the effluent data for a pollutant does not follow a log-normal distribution and provides an alternate distribution that more accurately describes the data, this alternate distribution may be used instead of the procedures in this subsection.(2) For the equations contained within this subsection, the following apply: (A) Z99 = 2.326 (99th percentile probability basis).(B) CV = coefficient of variation = ratio of the standard deviation to the mean. A value of six-tenths (0.6) will be used for the CV unless the discharger demonstrates that an alternate CV is more representative of the variability of the pollutant in the effluent.(3) The first step in this procedure is to calculate a long term average (LTA) for each WLA determined for the pollutant under section 11.4 of this rule. These LTAs are calculated as follows: (A) The LTAA protective of acute aquatic life effects shall be calculated as follows: Click here to view
Where: ó2 = ln(CV2 + 1).
WLAA = WLA determined under section 11.4 of this rule using the acute aquatic life criterion or value.
This WLA is expressed as a one (1) day maximum.
(B) The LTAC protective of chronic aquatic life effects shall be calculated as follows: Click here to view
Where: ó42= ln(CV2/4 + 1).
WLAC = For chloride, sulfate, total dissolved solids, fluoride, and dissolved iron, the more stringent WLA determined under section 11.4 of this rule using the criterion for the pollutant under 327 IAC 2-1.5-8(j), if applicable, or the chronic aquatic life criterion or value. For other pollutants, the WLA determined under section 11.4 of this rule using the chronic aquatic life criterion or value. This WLA is expressed as a four (4) day average.
(C) The LTAH protective of human health effects shall be calculated as follows: Click here to view
Where: ó302 = ln(CV2/30 + 1).
WLAH = The most stringent WLA determined under section 11.4 of this rule using a criterion or value for the protection of human health. This WLA is expressed as a thirty (30) day average.
(D) The LTAW protective of wildlife effects shall be calculated as follows: Click here to view
Where: ó302 = ln(CV2/30 + 1).
WLAW = WLA determined under section 11.4 of this rule using the WC or WV. This WLA is expressed as a thirty (30) day average.
(4) Daily maximum and monthly average WQBELs are determined using the lowest LTA calculated in subdivision (3) as follows:(A) The daily maximum WQBEL is calculated as follows: Click here to view
Where: ó2 = ln(CV2 + 1).
(B) The monthly average WQBEL is calculated as follows: Click here to view
Where: ón2 = ln(CV2/n + 1).
z95 = 1.645 (95th percentile probability basis).
n = Number of samples per month. A value of ten (10) will be used unless the discharger demonstrates that an alternate value is more appropriate.
(C) The monthly average WQBEL shall not exceed the most stringent WLA developed under section 11.4 of this rule unless calculated using the following: (i) A CV calculated using facility-specific effluent monitoring data that is representative of the variability of the pollutant in the effluent.(ii) A value for n based on the monitoring frequency in the NPDES permit to be issued.(d) Notwithstanding subsection (c), WQBELs for whole effluent toxicity (WET) and WQBELs for the criteria listed in section 11.4(d) of this rule shall be developed as follows: (1) For WET, WQBELs shall be developed using the WLAs for acute and chronic WET developed under section 11.4 of this rule as follows:(A) The commissioner shall ensure that the WQBELs for WET established under this subdivision attain the acute and chronic WET criteria in 327 IAC 2-1.5-8 under the receiving waterbody flows and outside the mixing zones used to develop the WLAs for acute and chronic WET under section 11.4 of this rule.(B) The commissioner shall determine, on a case-by-case basis, the following:(i) Whether to develop a WQBEL for only acute or chronic WET or WQBELs for both acute and chronic WET.(ii) The number of species required for WET testing.(iii) The particular species required for WET testing.(C) In making the determination in clause (B), the commissioner shall take into consideration available information about the discharge and receiving waterbody, including, but not limited to, the following:(i) The ACR of the effluent.(ii) The sensitivity of the test species to the toxicity in the effluent.(iii) The WLAs developed for acute and chronic WET under section 11.4 of this rule.(D) When the commissioner determines that it is necessary to develop a WQBEL for acute WET, the WQBEL shall be set equal to the WLA developed for acute WET under section 11.4 of this rule and shall be established in an NPDES permit as a daily maximum limit.(E) When the commissioner determines that it is necessary to develop a WQBEL for chronic WET, the WQBEL shall be set equal to the WLA developed for chronic WET under section 11.4 of this rule and shall be established in an NPDES permit as a monthly average limit.(2) For the criteria listed in section 11.4(d) of this rule, WQBELs shall be developed to be consistent with the models used in that subsection.(e) WQBELs in an NPDES permit for a metal calculated from a water quality criterion expressed in the form of dissolved metal that is:(1) contained in 327 IAC 2-1.5; or(2) subsequently developed under the procedures contained in 327 IAC 2-1.5; shall be expressed in the permit as total recoverable metal unless all approved analytical methods for the metal inherently measure only its dissolved form, such as hexavalent chromium.
(f) WQBELs for cyanide, calculated from a criterion for free cyanide contained in 327 IAC 2-1.5, shall be limited in the permit as free cyanide and monitored in the effluent using the "Cyanides Amenable to Chlorination" (CATC) method ( 40 CFR 136, Method 4500-CN G) or another method approved by the commissioner. The commissioner may include additional monitoring, limitations, or other requirements in a permit, on a case-by-case basis, if the additional requirements are necessary to ensure that water quality standards will be attained.(g) Whenever a WQBEL is developed, unless otherwise provided in subdivision (3), the WQBEL in the NPDES permit shall be expressed as both a concentration value and a corresponding mass loading rate as follows:(1) Both mass and concentration limits shall be based on the same permit averaging periods, such as daily, or monthly averages, or in other appropriate permit averaging periods.(2) The mass loading rates shall be calculated using effluent flow rates that are the same as those used in establishing the concentration-based WQBELs.(3) For pollutants or parameters that cannot appropriately be expressed in terms of mass (such as pH, temperature, radiation, bacteria, or dissolved oxygen) mass limits are not required.(4) A discharger may request tiered mass limits for a discharge that increases as a result of wet weather flow. As used in this subdivision, "tiered mass limits" consists of two (2) sets of mass limits. One (1) set shall be based on the dry-weather effluent flow determined under section 11.4(a)(9) of this rule and the stream design flow under section 11.4(b) of this rule. The second set shall be based on an effluent flow and stream flow under wet weather conditions. For each mass limit developed under this subdivision, the NPDES permit shall include a corresponding concentration limit.(h) When a WQBEL for a pollutant is calculated to be less than the LOQ, the following conditions apply: (1) The calculated WQBEL shall be established as the limit in the NPDES permit.(2) The analytical method, LOD, and LOQ shall be specified as follows:(A) The commissioner shall specify in the permit the most sensitive, applicable, analytical method, specified in or approved under 40 CFR 136 or by the commissioner, to be used to monitor for the presence and amount in an effluent of the pollutant for which the WQBEL is established and shall specify in accordance with clause (B), the LOD and LOQ that can be achieved by use of the specified analytical method. (B) The LOD and LOQ shall be determined as follows:(i) The MDL shall be used as the LOD unless the permittee demonstrates that a higher LOD is appropriate because of effluent-specific matrix interference.(ii) The LOQ shall be the ML specified in or approved under 40 CFR 136 for the method for that pollutant. If no such ML exists, or if the method is not specified or approved under 40 CFR 136 or by the commissioner, the LOQ shall be calculated by multiplying the LOD by three and eighteen-hundredths (3.18). The commissioner may specify a higher LOQ if the permittee demonstrates that a higher LOQ is appropriate because of effluentspecific matrix interference. Other methods for deriving an LOQ may be approved by the commissioner if the method is scientifically defensible.(3) Compliance with the WQBELs for the pollutant shall be determined as follows: (A) When a daily maximum WQBEL is less than the LOD specified in the permit, effluent levels: (i) of the pollutant less than the LOD are in compliance with the maximum WQBEL; and(ii) greater than the LOD but less than the LOQ are in compliance with the maximum WQBEL, except when confirmed by a sufficient number of analyses of multiple samples and use of appropriate statistical techniques.(B) When a daily maximum WQBEL is greater than the LOD specified in the permit but less than the LOQ specified in the permit, effluent levels of the pollutant less than the LOQ are in compliance with the WQBEL.(C) To determine compliance with a WQBEL expressed as a daily maximum mass limitation, the LOD and LOQ shall each be converted to a mass value, using appropriate conversion factors and the same effluent flow used to determine the mass-based WQBEL, before applying the provision of clauses (A) and (B).(D) When a monthly or weekly average WQBEL is less than the LOQ specified in the permit, a monthly or weekly average effluent level less than or equal to the respective monthly or weekly average WQBEL is in compliance with the monthly or weekly average WQBEL. Daily effluent values that are less than the LOQ, used to determine the monthly or weekly average effluent levels less than the LOQ, may be assigned a value of zero (0), unless, after considering the number of monitoring results that are greater than the LOD, and applying appropriate statistical techniques, a value other than zero (0) is warranted.(4) When a WQBEL is less than the LOD, the commissioner may require a period of accelerated monitoring in a permit, when the measured effluent level is between the LOD and LOQ, for the purpose of collecting additional data to apply the statistical analysis referenced in subdivision (3)(A) and (3)(D).(5) When a WQBEL is less than the LOQ, special conditions may be included in the permit to better quantify the levels of pollutant present in the discharge. These special conditions may include, but are not limited to, the following:(A) Fish tissue sampling.(D) Limits on internal wastestreams.(E) Monitoring requirements on internal wastestreams.(F) Development of a more sensitive analytical procedure.(G) Monitoring for surrogate parameters.(H) Waterbody bioassessment.(6) The permit shall contain reopener clauses authorizing modification or revocation and reissuance of the permit to:(A) include more stringent monitoring requirements or conditions if new information generated as a result of accelerated monitoring conducted in accordance with subdivision (4), or special conditions included in the permit in accordance with subdivision (5) indicates the likely presence of the pollutant in the discharge at levels above the WQBEL; and(B) specify the use of a different analytical method if a more sensitive analytical method has been specified in or approved under 40 CFR 136 or approved by the commissioner to monitor for the presence and amount in the effluent of the pollutant for which the WQBEL is established and shall specify in accordance with subdivision (2)(B), the LOD and LOQ that can be achieved by use of the specified analytical method.(7) The commissioner shall include a condition in the permit requiring the permittee to develop and conduct a pollutant minimization program (PMP) for each pollutant with a WQBEL below the LOQ in accordance with the following: (A) The goal of the PMP shall be to maintain the effluent at or below the WQBEL. The PMP shall include, but is not limited to, the following:(i) Submission of a control strategy designed to proceed toward the goal.(ii) Implementation of appropriate cost-effective control measures consistent with the control strategy.(iii) Monitoring necessary to monitor the progress toward the goal. This shall include, but is not limited to, the following:(AA) Semiannual monitoring of potential sources of the pollutant.(BB) Quarterly monitoring for the pollutant in the influent of the wastewater treatment system.(iv) An annual status report that shall be sent to the commissioner, including the following: (AA) All PMP monitoring results for the previous year.(BB) A list of potential sources of the pollutant.(CC) A summary of all actions taken to reduce or eliminate the identified sources of the pollutant.(v) A PMP may include the submittal of pollution prevention strategies that use changes in production process technology, materials, processes, operations, or procedures to reduce or eliminate the source of the pollutant.(B) No PMP is required if the permittee demonstrates that the discharge of a pollutant with a WQBEL below the LOQ is reasonably expected to be in compliance with the WQBEL at the point of discharge into the receiving water. This demonstration may include, but is not limited to, the following:(i) Treatment information, including information derived from modeling the destruction or removal of the pollutant in the treatment process.(ii) Mass balance information.(iii) Fish tissue studies or other biological studies.(C) In determining appropriate cost-effective control measures to be implemented in a PMP, the following factors may be considered: (i) Significance of sources.(ii) Economic and technical feasibility.(D) The permit shall contain a reopener clause authorizing modification or revocation and reissuance of the permit to revise (such as more or less frequent monitoring) or remove the requirements of this subdivision if supported by information generated as a result of this subdivision.(i) The determinations under this subsection regarding the consideration of intake pollutants, as defined under section 11.5(b)(4)(A) of this rule, shall be made on a pollutant-by-pollutant, outfall-by-outfall basis. This subsection applies only when the concentration of the pollutant of concern upstream of the discharge, as determined under section 11.4(a)(8) of this rule, exceeds the most stringent applicable water quality criterion or value for that pollutant. In addition, this subsection applies only in the absence of an EPA-approved TMDL applicable to the discharge, or in the absence of an assessment and remediation plan submitted and approved in accordance with section 11.4(a)(2) of this rule. The following procedures shall be used in the consideration of intake pollutants in establishing WQBELs:(1) When an intake pollutant is from the same body of water, as defined under section 11.5(b)(4)(B) of this rule, and the discharge and the facility meet the conditions in section 11.5(b)(4)(C)(i)(BB) through 11.5(b)(4)(C)(i)(EE), the following procedures apply:(A) The commissioner may establish effluent limitations allowing the facility to discharge a mass and concentration of the pollutant that are no greater than the mass and concentration of the pollutant identified in the facility's intake water (no net addition limitations). The permit shall specify how compliance with mass and concentration limitations shall be assessed. No permit may authorize no net addition limitations that are effective after March 23, 2007. After that date, WQBELs shall be established in accordance with section 11.5(d) of this rule.(B) Where proper operation and maintenance of a facility's treatment system results in removal of a pollutant, the commissioner may establish limitations that reflect the lower mass or concentration, or both, of the pollutant achieved by such treatment, taking into account the feasibility of establishing such limits.(C) For pollutants contained in intake water provided by a water system, the concentration of the intake pollutant shall be determined at the point where the raw water supply is removed from the same body of water, except that it shall be the point where the water enters the water supplier's distribution system where the water treatment system removes any of the identified pollutants from the raw water supply. Mass shall be determined by multiplying the concentration of the pollutant by the volume of the facility's intake flow received from the water system.(2) Where the pollutant in a facility's discharge originates from a water of the state that is not the same body of water as the receiving water, as determined in accordance with section 11.5(b)(4)(B) of this rule, WQBELs shall be established based upon the most stringent applicable water quality criterion or value for that pollutant.(3) Where a facility discharges intake pollutants that originate in part from the same body of water, and in part from a different body of water, the commissioner may apply the procedures of subdivisions (1) and (2) to derive an effluent limitation reflecting the flow-weighted average of each source of the pollutant, provided that adequate monitoring to determine compliance can be established and is included in the permit.Water Pollution Control Board; 327 IAC 5-2-11.6; filed Jan 14, 1997, 12:00 p.m.: 20 IR 1457; errata filed Aug 11, 1997, 4:15 p.m.: 20 IR 3379; errata, 26 IR 3884; filed Feb 14, 2005, 10:05 a.m.: 28 IR 2120; filed Jul 9, 2012, 2:54 p.m.: 20120808-IR-327110320FRAReadopted filed 10/18/2024, 1:57 p.m.: 20241113-IR-327230810RFA