Illinois Administrative Code
Title 35 - ENVIRONMENTAL PROTECTION
Part 375 - COMBINED SEWER OVERFLOW EXCEPTION CRITERIA AND FIRST FLUSH DETERMINATION
Subpart C - ASSESSMENT OF CONTROL OPTIONS
Section 375.303 - Benefits Assessment
Current through Register Vol. 48, No. 38, September 20, 2024
Benefits shall not be assessed solely on a pound pollutant removed basis but also on instream improvement of a documented pollutional impact or reduction in a public health risk. Acceptable techniques for estimating water quality improvements will vary depending on individual circumstances but may include:
a) consideration of receiving water body assimilative capabilities and strategic relocation of overflows;
b) selection of size of storm to design controls for based on stream hydrograph, available dilution, turbulance and velocity under storm conditions and their affect on assimilation (since CSO's are dominated by suspended rather than soluble pollutants, major emphasis will be placed on prevention of instream deposition); and
c) mathematic modeling.
