35 Ill. Adm. Code 375.401
Variables in First Flush Determination
Section 375
Section 375.401 Variables in
First Flush Determination
The intensity and duration of
first flush are a function of certain variables including:
a) Physical and hydraulic features of the sewer system and
tributary watershed.
b) Amount of sediment accumulated in the sewer system and on
impervious surfaces of the watershed.
c) Intensity and duration of the storm event causing the
flushing.