Section 306.305  Treatment of Overflows and Bypasses

All combined sewer overflows and treatment plant bypasses shall be given sufficient treatment to prevent pollution, or the violation of applicable water quality standards unless an exception has been granted by the Board pursuant to Subpart D.  Sufficient treatment shall consist of the following:

a)         All dry weather flows, and the first flush of storm flows as determined by the Agency, shall meet the applicable effluent standards; and

b)         Additional flows, as determined by the Agency but not less than ten times the average dry weather flow for the design year, shall receive a minimum of primary treatment and disinfection with adequate retention time; and

c)         Flows in excess of those described in subsection (b) shall be treated, in whole or in part, to the extent necessary to prevent accumulations of sludge deposits, floating debris and solids in accordance with 35 Ill. Adm. Code 302.203, and to prevent depression of oxygen levels; or

d)         Compliance with a treatment program authorized by the Board in an exception granted pursuant to Subpart D.

(Source:  Section 306.305 was renumbered from Section 305.103(c) and amended at 7 Ill. Reg. 5682, effective April 19, 1983)