The following definitions are applicable to secondary treatment standards:

1. (1) "Seven-day average," the arithmetic mean of pollutant parameter values of samples collected in a period of seven consecutive days;
2. (2) "30-day average," the arithmetic mean of pollutant parameter values of samples collected in a period of 30 consecutive days;
3. (3) "BOD₅," the five-day measure of the pollutant parameter biochemical oxygen demand;
4. (4) "CBOD₅," the five-day measure of the pollutant parameter carbonaceous biochemical oxygen demand;
5. (5) "Effluent concentrations consistently achievable through proper operation and maintenance," for a given pollutant parameter, the 95th percentile value for the 30-day average effluent quality achieved by a treatment works in a period of at least two years, excluding values attributable to upsets, bypasses, operational errors, or other unusual conditions, and a seven-day average value equal to 1.5 times this value;
6. (6) "mg/L," milligrams per liter;
7. (7) "Percent removal," a percentage expression of the removal efficiency across a treatment plant for a given pollutant parameter, as determined from the 30-day average values of the raw wastewater influent pollutant concentrations to the facility and the 30-day average values of the effluent pollutant concentrations;
8. (8) "TSS," total suspended solids; and
9. (9) "Significantly more stringent limitations," BOD₅ and TSS limitations necessary to meet the percent removal requirements of at least five mg/L more stringent than the otherwise applicable concentration-based limitations.

Source: 14 SDR 86, effective December 24, 1987; 19 SDR 122, effective February 21, 1993; transferred from § 74:03:22:01, July 1, 1996.

General Authority: SDCL 34A-2-30.

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