Ill. Admin. Code tit. 35, § 611.954 - Disinfection Benchmark

a) Applicability. A Subpart B system supplier that is required to develop a disinfection profile under Section 611.953 must develop a disinfection benchmark if it decides to make a significant change to its disinfection practice. The supplier must consult with the Agency for approval before it can implement a significant disinfection practice change.

b) Significant Changes to Disinfection Practice. Significant changes to disinfection practice include the following:

1) Changes to the point of disinfection;

2) Changes to the disinfectants used in the treatment plant;

3) Changes to the disinfection process; or

4) Any other modification identified by the Agency.

c) Considering a Significant Change. A supplier that is considering a significant change to its disinfection practice must calculate disinfection benchmark, as described in subsections (d) and (e), and provide the benchmarks to the Agency. A supplier may only make a significant disinfection practice change after consulting with the Agency for approval. A supplier must submit the following information to the Agency as part of the consultation and approval process:

1) A description of the proposed change;

2) The disinfection profile for Giardia lamblia (and, if necessary, viruses) and disinfection benchmark;

3) An analysis of how the proposed change will affect the current levels of disinfection; and

4) Any additional information requested by the Agency.

d) Calculation of a Disinfection Benchmark. A supplier that is making a significant change to its disinfection practice must calculate a disinfection benchmark using the following procedure:

1) Step 1: Using the data that the supplier collected to develop the disinfection profile, determined the average Giardia lamblia inactivation for each calendar month by dividing the sum of all Giardia lamblia inactivations for that month by the number of values calculated for that month; and

2) Step 2: Determine the lowest monthly average value out of the 12 values. This value becomes the disinfection benchmark.

e) If a supplier uses chloramines, ozone or chlorine dioxide for primary disinfection the supplier must calculate the disinfection benchmark from the data that the supplier collected for viruses to develop the disinfection profile in subsection (d). This viral benchmark must be calculated in the same manner used to calculate the Giardia lamblia disinfection benchmark in subsection (d).

Notes

Ill. Admin. Code tit. 35, § 611.954

Amended at 28 Ill. Reg. 5269, effective March 10, 2004

Amended at 42 Ill. Reg. 1140, effective 1/4/2018 Amended at 44 Ill. Reg. 6996, effective 4/17/2020

BOARD NOTE: Derived from 40 CFR 141.540 through 141.544.