Subsection 096-525-3-VI - Treatment equivalent to secondary treatment [see 40 CFR 133.105]This subsection describes the minimum level of effluent quality attainable by facilities eligible for treatment equivalent to secondary treatment (Subsection II(g)) in terms of the parameters--BOD-5, SS and pH. All requirements for the specified parameters in paragraphs(a), (b) and (c) of this subsection shall be achieved except as provided for in Subsection IV, or paragraphs (d), (e) or (f) of this subsection.
(a) BOD-5. (1) The 30-day average shall not exceed 45 mg/l(2) The 7-day average shall not exceed 65 mg/l.(3) The 30-day average percent removal shall not be less than 65 percent.(b) SS. Except where SS values have been adjusted in accordance with Subsection IV(c): (1) The 30-day average shall not exceed 45 mg/l.(2) The 7-day average shall not exceed 65 mg/l.(3) The 30-day average percent removal shall not be less than 65 percent.(c) pH. The requirements of Subsection III(c) shall be met.(d) Alternative State requirements. Except as limited by paragraph(f) of this subsection, and after notice and opportunity for public comment, the Department, subject to EPA approval, is authorized to adjust the minimum levels of effluent quality set forth in paragraphs (a)(1), (a)(2), (b)(1) and (b)(2) of this subsection for trickling filter facilities and in paragraphs (a)(1) and (a)(2) of this subsection for waste stabilization pond facilities, to conform to the BOD-5 and SS effluent concentrations consistently achievable through proper operation and maintenance (Subsection II(f)) by the median (50th percentile) facility in a representative sample of facilities within a State or appropriate contiguous geographical area that meet the definition of facilities eligible for treatment equivalent to secondary treatment (Subsection II(g)).(e) CBOD-5 limitations: (1) Where data are available to establish CBOD-5 limitations for a treatment works subject to this subsection, the NPDES permitting authority may substitute the parameter CBOD-5 for the parameter BOD-5 in Subsections VI(a)(1), (a)(2) and (a)(3), on a case-by-case basis provided that the levels of CBOD-5 effluent quality are not less stringent than the following: (i) The 30-day average shall not exceed 40 mg/l.(ii) The 7-days average shall not exceed 60 mg/l.(iii) The 30-day average percent removal shall not be less than 65 percent.(2) Where data are available, the parameter CBOD-5 may be used for effluent quality limitations established under paragraph (d) of this subsection. Where concurrent BOD effluent data are available, they must be submitted with the CBOD data as a part of the approval process outlined in paragraph (d) of this subsection.(f) Permit adjustments. Any permit adjustment made pursuant to this Chapter may not be any less stringent than the limitations required pursuant to Subsections VI(a)-(e). Furthermore, permitting authorities shall require more stringent limitations when adjusting permits if: (1) For existing facilities the permitting authority determines that the 30-day average and 7-day average BOD-5 and SS effluent values that could be achievable through proper operation and maintenance of the treatment works, based on an analysis of the past performance of the treatment works, would enable the treatment works to achieve more stringent limitations, or(2) For new facilities, the permitting authority determines that the 30-day average and 7-day average BOD-5 and SS 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. C.M.R. 06, 096, ch. 525, § 096-525-3, subsec. 096-525-3-VI