35 Ill. Adm. Code 378.301
Die-off Equation
Section 378
Section 378.301 Die-off
Equation
a) The permittee shall model the die-off of fecal coliform from
its discharge using the first-order die-off equation provided in Appendix A of
this Part. Appendix B of this Part provides step-by-step guidance for the
application of this equation. Appendices C through E of this Part provide
further assistance in the application of the equation.
b) The die-off equation predicts levels of fecal coliform at
points downstream from the fecal coliform source. The equation includes
variables to reflect upstream levels of fecal coliform, changes in dilution and
travel time, and other stream-specific parameters.
c) In modeling the effects of its discharge, the permittee shall
collect additional stream-specific information as necessary to demonstrate
compliance with fecal coliform water quality standards. The amount of field
data necessary to utilize the equation as specified in Appendix B of this Part
will depend on the proximity of the source to protected waters and the nature
of the receiving waters. Additional field data collected will produce more
accurate prediction of downstream levels of fecal coliform.