35 Ill. Adm. Code 364.402
F4 Factor
Section 364
Section 364.402 F4 Factor
a) The F4 factor considers the corrective measures necessary to
provide the degree of treatment required by applicable effluent limitations.
F4 is derived through a summation of values assigned for additional treatment
process required for currently overloaded facilities and for rehabilitation.
b) The F4 factor establishes relative values for the following
treatment processes:
1) addition of any required secondary or supplemental treatment
processes where, at the present time, the required processes are non-existent.
2) addition of capacity for currently (hydraulically and/or
organically) overloaded treatment processes.
3) modification of existing processes which do not increase
capacity or degree of treatment but are necessary for the upgrading of an existing
treatment plant.
4) the construction of new trunk and lateral sewers to provide an
extension of service from an existing collection system or the rehabilitation
of existing sewers, which will not eliminate excessive infiltration/inflow.
5) the construction of a new collection system and treatment
works to service a presently unsewered community where a discharge of raw or
partially treated sewage exists, or where no discharge exists.
c) The F4 values are the following:
TABLE
OF F4 VALUES
Treatment Process
Average
Dry Weather Flow
Maximum
Dry Weather Flow
Maximum
Wet Weather Flow
Primary
0
0
8
Secondary
14
10
0
Tertiary (10/12)
8
6
0
Disinfection
6
6
6
Phosphorus Removal
5
3
0
Nitrification
8
6
0
Inadequate Sludge Processing
Facilities
6
Modification of existing
processes which do not increase capacity or degree of treatment
1
or
Wastewater reuse or recycling;
Flood control projects; Trunk and Lateral Sewers
1
Range
of Values: 0 to 99