Ill. Admin. Code tit. 35, § 611.742 - Disinfection Profiling and Benchmarking
a) Determination of a Supplier Required to
Profile. A PWS supplier subject to this Subpart R must determine its TTHM
annual average under subsection (a)(1) and its HAA5 annual average under
subsection (a)(2). The annual average is the arithmetic average of the
quarterly averages from four consecutive quarters of monitoring.
1) The supplier must use the TTHM annual
average during the same period as the HAA5 annual average.
A) A supplier that collected data under 40
CFR 141 Subpart M (Information Collection Rule) must use the results of the
samples collected during the last four quarters of required monitoring under
former 40 CFR
141.42 (1995).
B) A supplier using "grandfathered" HAA5
occurrence data under subsection (a)(2)(B) must use TTHM data it collected at
the same time under former Section
611.680.
2) The HAA5 annual average the supplier uses
must be the annual average during the same period as the TTHM annual average.
A) A supplier that collected data under the
provisions of 40 CFR 141 Subpart M (Information Collection Rule) must use the
results of the samples it collected during the last four quarters of required
monitoring under former 40
CFR 141.42 (1995).
B) A supplier that collected four quarters of
HAA5 occurrence data meeting the routine monitoring sample number and location
requirements for TTHM in former Section
611.680 and handling and
analytical method requirements of former Section
611.685 may use that data to
determine whether this Section applies.
C) A supplier that has not collected four
quarters of HAA5 occurrence data complying with either subsection (a)(2)(A) or
(a)(2)(B) must do either of two things:
i)
Conduct monitoring for HAA5 meeting the routine monitoring sample number and
location requirements for TTHM in former Section
611.680 and handling and
analytical method requirements of former Section
611.685 to determine the HAA5
annual average and whether subsection (b) applies; or
ii) Comply with all other provisions of this
Section as if the supplier had conducted the HAA5 monitoring and the results
required the supplier to comply with subsection (b).
3) The supplier may request that
the Agency approve a more representative annual data set than the data set
under subsection (a)(1) or (a)(2) for determining applicability of this
Section.
4) The Agency may require
a supplier to use a more representative annual data set than the data set under
subsection (a)(1) or (a)(2) for determining applicability of this
Section.
5) This subsection (a)(5)
corresponds with 40 CFR
141.172(a)(5), an
implementing provision that no longer has operative effect. This statement
maintains structural consistency with the corresponding federal
rules.
6) Any supplier that had
either a TTHM annual average [GREATER THAN OR EQUAL TO] (greater than or equal
to) 0.064 mg/L or an HAA5 annual average [GREATER THAN OR EQUAL TO] 0.048 mg/L
under subsections (a)(1) and (a)(2) must comply with subsection (b).
BOARD NOTE: Former Sections 611.680 and 611.685 originally derived from 40 CFR 141.30(a), (b), and (e) . USEPA removed 40 CFR 141.30 in its entirety in 2006. The Board repealed former Section 611.685 in 2007 and Section 611.680 in 2012. The references to former Sections 611.680 and 611.685 in this subsection (a) relate to using existing monitoring data collected under those provisions as they existed before their repeal.
b) Disinfection Profiling
1) Any supplier complying with subsection
(a)(6) was to develop a disinfection profile of its disinfection practice for a
period of up to three years. The Agency was to determine the period of the
disinfection profile, with a minimum period of one year.
2) The supplier must monitor daily for a
period of 12 consecutive calendar months to determine the total logs of
inactivation for each day of operation, based on the appropriate
CT99.9 values in Appendix B through the entire treatment
plant. As a minimum, the supplier applying disinfection treatment at a single
point before the entry point to its distribution system was to conduct the
monitoring under subsections (b)(2)(A) through (b)(2)(D). A supplier applying
disinfection treatment at more than one point in its distribution system was to
conduct the monitoring under subsections (b)(2)(A) through (b)(2)(D) for each
disinfection segment. The supplier was to monitor the parameters necessary to
determine the total inactivation ratio, using analytical methods in Section
611.531:
A) The supplier was to measure the
temperature of the disinfected water once per day at each residual disinfectant
concentration sampling point during peak hourly flow.
B) If the supplier uses chlorine, the
supplier was to measure the pH of the disinfected water once per day at each
chlorine residual disinfectant concentration sampling point during peak hourly
flow.
C) The supplier was to
determine the disinfectant contact times ("T") for each day during peak hourly
flow.
D) The supplier was to
measure the residual disinfectant concentrations ("C") of the water before or
at the first customer and prior to each additional point of disinfection each
day during peak hourly flow.
3) This subsection (b)(3) corresponds with
40 CFR
141.172(b)(2)(A), a
provision relating to implementation of the Interim Enhanced Surface Water
Treatment Rule. This statement maintains structural consistency with the
corresponding federal rule.
4) The
supplier must calculate the total inactivation ratio:
A) A supplier using only one point of
disinfectant application may determine the total inactivation ratio for its
disinfection segment under subsection (b)(4)(A)(i) or (b)(4)(A)(ii).
i) The supplier may determine one
inactivation ratio
(CTcalc/CT99.9) before or at the
first customer during peak hourly flow; or
ii) The supplier may determine successive
CTcalc/CT99.9 values,
representing sequential inactivation ratios, between the point where applying
disinfectant and a point before or at the first customer during peak hourly
flow. Under this alternative, the supplier must calculate the total
inactivation ratio ([SIGMA]
(CTcalc/CT99.9)) by determining
CTcalc/CT99.9 for each step in
the sequence, then summing the
CTcalc/CT99.9 values for each
step to determine [SIGMA]
(CTcalc/CT99.9).
B) A supplier applying
disinfection treatment at more than one point before the first customer must
determine the CT value of each disinfection segment during peak hourly flow
immediately prior to the next point where applying or before or at the first
customer for the final segment. The supplier must calculate the
(CTcalc/CT99.9) value of each
segment and
([SIGMA](CTcalc/CT99.9))
using the method in subsection (b)(4)(A).
C) The supplier must determine the total logs
of inactivation by multiplying the value calculated under subsection (b)(4)(A)
or (b)(4)(B) by 3.0.
5)
A supplier using chloramines or ozone for primary disinfection must also
calculate the logs of inactivation for viruses using an Agency-approved
method.
6) The supplier must
maintain disinfection profile data in graphic form, as a spreadsheet or in some
other format acceptable to the Agency, for review as part of sanitary surveys
the Agency conducts.
c)
Disinfection Benchmarking
1) A supplier that
must develop a disinfection profile under the subsections (a) and (b) deciding
to significantly change its disinfection practice must obtain Agency approval
before making the change. Certain changes are significant changes to
disinfection practice:
A) A change in the
point where the supplier applies disinfection treatment;
B) A change in the disinfectant the supplier
uses in its treatment plant;
C) A
change in the supplier's disinfection process; and
D) Any other modification the Agency
identifies as a significant change in a SEP.
2) Any supplier modifying its disinfection
practice must calculate its disinfection benchmark using the procedure in
subsections (c)(2)(A) and (c)(2)(B).
A) For
each year of profiling data a supplier collects and calculates under subsection
(b), the supplier must determine the lowest average monthly Giardia lamblia
inactivation in each year of profiling data. The supplier must determine the
average Giardia lamblia inactivation for each calendar month for each year of
profiling data by dividing the sum of daily Giardia lamblia of inactivation by
the number of values calculated for that month.
B) The disinfection benchmark is the lowest
monthly average value (for a supplier with one year of profiling data) or
average of lowest monthly average values (for a supplier with more than one
year of profiling data) of the monthly logs of Giardia lamblia inactivation in
each year of profiling data.
3) A supplier using chloramines or ozone for
primary disinfection must also calculate the disinfection benchmark for viruses
using an Agency-approved method.
4)
The supplier must submit the information in subsections (c)(4)(A) through
(c)(4)(C) to the Agency when seeking Agency approval.
A) A description of the proposed
change;
B) The disinfection profile
for Giardia lamblia (and viruses if necessary) under subsection (b) and
benchmark as subsection (c)(2) requires; and
C) An analysis of how the proposed change
will affect the current levels of disinfection.
Notes
Amended at 28 Ill. Reg. 5269, effective March 10, 2004
BOARD NOTE: This Section derives from 40 CFR 141.172.
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