La. Admin. Code tit. 33 § IX-5907

Current through Register Vol. 50, No. 11, November 20, 2024

Section IX-5907 - Special Considerations

A. Combined Sewers. Treatment works subject to this Chapter may not be capable of meeting the percentage removal requirements established under LAC 33:IX.5905.A.3 and B.3, or 5911.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 Wastes. For certain industrial categories, the discharge to navigable waters of BOD₅ and TSS permitted under Sections 301(b)(1)(A)(i), (b)(2)(E) of the Act may be less stringent than the values given in LAC 33:IX.5905.A.1, A.4.a, B.1, 5911.A.1, B.1, and E.1.a. 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 LAC 33:IX.5905.A.1, A.4.a, B.1, 5911.A.1, B.1, and E.1.a may be adjusted upwards provided that:

1. the permitted discharge of such pollutants, attributable to the industrial category, would not be greater than that which would be permitted under Sections 301(b)(1)(A)(i) of the Act if such industrial category were to discharge directly into the navigable waters; 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 LAC 33:IX.5905.A.2, A.4.b, B.2, 5911.A.2, B.2, and E.1.b should be adjusted proportionately.

C. Waste Stabilization Ponds. The EPA regional administrator, or, if appropriate, state administrative authority subject to EPA approval, is authorized to adjust the minimum levels of effluent quality set forth in LAC 33:IX.5911.B.1-3 for treatment works subject to this Chapter, to conform to the TSS concentrations achievable with waste stabilization ponds, provided that:

1. waste stabilization ponds are the principal process used for secondary treatment; and

2. operation and maintenance data indicate that the TSS values specified in LAC 33:IX.5911.B.1-3 cannot be achieved. The term TSS concentrations achievable with waste stabilization ponds means a TSS value, determined by the EPA regional administrator, or, if appropriate, state administrative authority subject to EPA approval, which is equal to the effluent concentration achieved 90 percent of the time within the state or appropriate contiguous geographical area by waste stabilization ponds that are achieving the levels of effluent quality for BOD₅ specified in LAC 33:IX.5911.A.1.

D. Less Concentrated Influent Wastewater for Separate Sewers. The EPA regional administrator, or if appropriate, state administrative authority is authorized to substitute either a lower percent removal requirement or a mass loading limit for the percent removal requirements set forth in LAC 33:IX.5905.A.3, 4.b, B.3, 5911.A.3, B.3, and E.1.c provided that the permittee satisfactorily demonstrates that:

1. 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;

2. 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

3. the less concentrated influent wastewater is not the result of excessive Inflow/Infiltration (I/I). The determination of whether the less concentrated wastewater is the result of excessive I/I will use the definition of excessive I/I in 40 CFR 35.2005(b)(16) plus the additional criterion that inflow is nonexcessive if the total flow to the POTW (i.e., wastewater plus inflow plus infiltration) is less than 275 gallons per capita per day.

E. Less Concentrated Influent Wastewater for Combined Sewers during Dry Weather. The EPA regional administrator or, if appropriate the state administrative authority, is authorized to substitute either a lower percent removal requirement or a mass loading limit for the percent removal requirements set forth in LAC 33:IX.5905.A.3, A.4.c, B.3, or 3311.A.3, B.3, and E.1.c provided that the permittee satisfactorily demonstrates that:

1. the treatment works is consistently meeting, or will consistently meet, its permit effluent concentration limitations, but the percent removal requirements cannot be met due to less concentrated influent wastewater;

2. 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

3. the less concentrated influent wastewater flows not result from either excessive infiltration 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 35.2005(b)(28), plus the additional criterion that either 40 gallons per capita per day (gpcd) or 1500 gallons per inch diameter per mile of sewer (gpdim) may be used as the threshold value for that portion of the dry weather base flow attributed to the 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 LAC 33:IX.Chapter 61.

La. Admin. Code tit. 33, § IX-5907

Promulgated by the Department of Environmental Quality, Office of Water Resources, LR 21:945 (September 1995), repromulgated by the Office of Environmental Assessment, Environmental Planning Division, LR 30:232 (February 2004).

AUTHORITY NOTE: Promulgated in accordance with R.S. 30:2001 et seq., and in particular Section 2074(B)(3) and (B)(4)