Section 310.301  Special Definitions

For Subpart C, the following definitions apply:

"Consistent removal" means the average of the lowest 50% of the removals measured according to Section 310.311.  All sample data obtained for the measured pollutant during the time period prescribed in Section 310.311 must be reported and used in computing consistent removal.  If a substance is measurable in the influent but not in the effluent, the effluent level may be assumed to be the limit of measurement, and those data may be used by the POTW at its discretion and subject to approval by the Agency.  If the substance is not measurable in the influent, the data may not be used. If the number of samples with concentrations equal to or above the limit of measurement is between eight and twelve, the average of the lowest six removals must be used.  If there are less than eight samples with concentrations equal to or less than the limit of measurement, the Agency may approve alternate means of demonstrating consistent removal. "Measurement" refers to the ability of the analytical method or protocol to quantify as well as identify the presence of the substance in question.

BOARD NOTE:  Derived from 40 CFR 403.7 (2005).

"Industrial user" means industrial user or users, as is appropriate from the context.

"Overflow" means the intentional or unintentional diversion of flow from the POTW before the POTW treatment plant.

BOARD NOTE: Derived from 40 CFR 403.7 (2005), as amended at 70 Fed. Reg. 60134 (Oct. 14, 2005).

"Removal" means a reduction in the amount of a pollutant in the POTW's effluent or alteration of the nature of a pollutant during treatment at the POTW.  The reduction or alteration can be obtained by physical, chemical, or biological means and may be the result of specifically designed POTW capabilities, or may be incidental to the treatment system's operation. Removal does not mean dilution of a pollutant in a POTW.

BOARD NOTE:  Derived from 40 CFR 403.7(a) (2005).

"Sludge requirements" is as defined in Section 310.110.

BOARD NOTE:  Derived from 40 CFR 403.7(a) (2005).

"Standard" means standard or standards as is appropriate from the context.

(Source:  Amended at 47 Ill. Reg. 5083, effective March 23, 2023)