S.D. Admin. R. 74:52:06:04

Current through Register Vol. 51, page 54, October 28, 2024

Section 74:52:06:04 - Special considerations

The following special considerations apply to the secondary treatment requirements:

(1) The POTWs subject to this chapter may not be capable of meeting the percentage removal requirements established under § 74:52:06:03 during wet weather where the treatment works receive flows from combined 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;

(2) The secretary, subject to EPA approval, may adjust the minimum levels of effluent quality required for POTWs in subdivision 74:52:06:03(3) to conform to the TSS concentrations achievable with waste stabilization ponds if the following conditions are met:

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

(b) Operation and maintenance data indicate that the TSS values specified in subdivision 74:52:06:03 (3) cannot be achieved;

(c) The effluent quality for TSS does not exceed 110 mg/L for 30-day average and 165 mg/L for 7-day average; and

(d) The POTW is achieving levels of effluent quality required for BOD₅ specified in § 74:52:06:03;

(3) For less concentrated influent wastewater for separate sewers, the secretary may substitute either a lower percent removal requirement or a mass loading limit for the percent removal requirements set forth in § 74:52:06:03 if the permittee satisfactorily demonstrates that;

(a) 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;

(b) 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

(c) The less concentrated influent wastewater is not the result of excessive infiltration or inflow, or both. The determination of whether the less concentrated wastewater is the result of excessive infiltration or inflow shall use the definition of excessive infiltration or inflow in 40 C.F.R. § 35.2005 (b)(16) (July 1, 1991), plus the additional criterion that inflow is nonexcessive if the total flow to the POTW is less than 275 gallons per capita per day.

S.D. Admin. R. 74:52:06:04

14 SDR 86, effective 12/24/1987; 19 SDR 122, effective 2/21/1993; transferred from

General Authority: SDCL 34A-2-30.

Law Implemented: SDCL 34A-2-13, 34A-2-20.