35 Ill. Adm. Code 375.303
Benefits Assessment
Section 375
Section 375.303 Benefits
Assessment
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.