327 IAC 8-2.6-2 - Disinfection profiling and benchmarking for systems serving a population of at least 10,000 individuals
Authority: IC 13-13-5-1; IC 13-14-8-2; IC 13-14-8-7; IC 13-18-3-2
Affected: IC 13-12-3-1; IC 13-13-5-2; IC 13-14-9; IC 13-18-11
Sec. 2.
(a) A public
water system subject to this section will determine its TTHM annual average
using the procedure in subdivision (1) and its HAA5 annual average using the
procedure in subdivision (2). The annual average is the arithmetic average of
the quarterly averages of four (4) consecutive quarters of monitoring. A public
water system subject to this section shall meet the following monitoring
requirements to determine its TTHM annual average and its HAA5 annual average:
(1) The TTHM annual average must be the
annual average during the same period as is used for the HAA5 annual average.
Those Subpart H systems serving a population of at least ten thousand (10,000)
individuals that:
(A) collected data under 40
CFR 141 * must use the results of the samples collected during the last four
(4) quarters of required monitoring under 40 CFR 141.142 *;
(B) use grandfathered HAA5 occurrence data
that meet the provisions of subdivision (2)(B) must use the TTHM data collected
at the same time under
327
IAC 8-2-5(a) and
327
IAC 8-2-5.3; and
(C) use HAA5 occurrence data that meet the
provisions of subdivision (2)(C)(i) must use the TTHM data collected at the
same time under
327
IAC 8-2-5(a) and
327
IAC 8-2-5.3.
(2) The HAA5 annual average must be the
annual average during the same period as is used for the TTHM annual average.
Those Subpart H systems serving a population of at least ten thousand (10,000)
individuals that:
(A) collected data under 40
CFR 141 * must use the results of the samples collected during the last four
(4) quarters of required monitoring under 40 CFR 141.142 *;
(B) have collected four (4) quarters of HAA5
occurrence data that meets the routine monitoring sample number and location
requirements for TTHM in
327
IAC 8-2-5(a) and
327
IAC 8-2-5.3 and handling and analytical method
requirements of 40 CFR 141.142(b)(1) * may use those data to determine whether
this section applies; and
(C) have
not collected four (4) quarters of HAA5 occurrence data that meets the
provisions of clause (A) or (B) by March 16, 1999, must either:
(i) conduct monitoring for HAA5 that meets
the routine monitoring sample number and location requirements for TTHM in
327
IAC 8-2-5(a),
327
IAC 8-2-5.3, and handling and analytical method
requirements of 40 CFR 141.142(b)(1) * to determine the HAA5 annual average and
whether subsection (b) applies. This monitoring must be completed so that the
applicability determination can be made no later than March 31, 2000;
or
(ii) comply with all other
provisions of this section as if the HAA5 monitoring had been conducted and the
results required compliance with subsection (b).
(3) Subpart H systems serving a
population of at least ten thousand (10,000) individuals may request that the
commissioner approve a more representative annual data set than the data set
determined under subdivision (1) or (2) for the purpose of determining
applicability of this section.
(4)
The commissioner may require that a system use a more representative annual
data set than the data set determined under subdivision (1) or (2) for the
purpose of determining applicability of this section.
(5) Subpart H systems serving a population of
at least ten thousand (10,000) individuals shall submit data to the
commissioner based on the following schedules:
(A) Those Subpart H systems serving a
population of at least ten thousand (10,000) individuals that collected TTHM
and HAA5 data under 40 CFR 141 *, as required by subdivisions (1)(A) and
(2)(A), shall submit the results of the samples collected during the last
twelve (12) months of monitoring required under 40 CFR 141.142 * not later than
December 31, 1999.
(B) Those
Subpart H systems serving a population of at least ten thousand (10,000)
individuals that have collected four (4) consecutive quarters of HAA5
occurrence data that meets the routine monitoring sample number and location
for TTHM in
327
IAC 8-2-5(a),
327
IAC 8-2-5.3, and handling and analytical method
requirements of 40 CFR 141.142(b)(1) *, as allowed by subdivisions (1)(B) and
(2)(B), must submit those data to the commissioner not later than April 15,
1999. Until the commissioner has approved the data, the system shall conduct
monitoring for HAA5 using the monitoring requirements specified under
subdivision (2)(C).
(C) Subpart H
systems serving a population of at least ten thousand (10,000) individuals that
conduct monitoring for HAA5 using the monitoring requirements specified by
subdivision (2)(C)(i) shall submit TTHM and HAA5 data not later than March 31,
2000.
(D) Those systems that elect
to comply with all other provisions of this section as if the HAA5 monitoring
had been conducted and the results required compliance with this section, as
allowed under subdivision (2)(C)(ii), shall notify the commissioner in writing
of their election not later than December 31, 1999.
(E) If the system elects to represent that
the commissioner approve a more representative annual data set than the data
set determined under subdivision (2)(A), the system must submit this request in
writing not later than December 31, 1999.
(6) Any Subpart H systems serving a
population of at least ten thousand (10,000) individuals having either a TTHM
annual average greater than or equal to sixty-four thousandths (0.064)
milligram per liter or an HAA5 annual average greater than or equal to
forty-eight thousandths (0.048) milligram per liter during the period
identified in subdivisions (1) and (2) shall comply with subsection
(b).
(b) Disinfection
profiling requirements are as follows:
(1) Any
Subpart H system serving a population of at least ten thousand (10,000)
individuals that meets the criteria in subsection (a)(6) shall develop a
disinfection profile of its disinfection practice for a period of up to three
(3) years.
(2) Not later than April
1, 2000, Subpart H systems serving a population of at least ten thousand
(10,000) individuals shall monitor daily for a period of twelve (12)
consecutive calendar months to determine the total logs of inactivation for
each day of operation based on the CT99.9 values in Tables 1.1 through 1.6,
2.1, and 3.1 of
40 CFR
141.74(b) *, as appropriate,
through the entire treatment plant. At a minimum, Subpart H systems serving a
population of at least ten thousand (10,000) individuals with a single or
multiple point of disinfectant application prior to entrance to the
distribution system shall conduct the monitoring in clauses (A) through (D) for
each disinfection segment. The system shall monitor the parameters necessary to
determine the total inactivation ratio using analytical methods in
327
IAC 8-2-8.7 as follows:
(A) The temperature of the disinfection water
shall be measured one (1) time per day at each residual disinfectant
concentration sampling point during peak hourly flow.
(B) If the system uses chlorine, the pH of
the disinfected water shall be measured one (1) time per day at each chlorine
residual disinfectant concentration sampling point during peak hourly
flow.
(C) The disinfectant contact
time (T) shall be determined for each day during peak hourly flow.
(D) The residual disinfectant concentration
(C) of the water before or at the first customer and prior to each additional
point of disinfection shall be measured each day during peak hourly
flow.
(3) Instead of the
monitoring conducted under subdivision (2) to develop the disinfection profile,
Subpart H systems serving a population of at least ten thousand (10,000)
individuals may elect to meet either of the following requirements:
(A) Not later than March 31, 2000, Subpart H
systems serving a population of at least ten thousand (10,000) individuals that
have three (3) years of existing operational data may submit those data, a
profile generated using those data, and a request that the commissioner approve
use of those data instead of monitoring under subdivision (2). The commissioner
shall determine whether these operational data are substantially equivalent to
data collected under subdivision (2) and whether these data are representative
of Giardia lamblia inactivation through the entire treatment plant and not just
of certain treatment segments. Until the commissioner approves this request,
the system is required to conduct monitoring under subdivision (2).
(B) In addition to the disinfection profile
generated under subdivision (2), Subpart H systems serving a population of at
least ten thousand (10,000) individuals that have existing operational data may
use those data to develop a disinfection profile for additional years. Subpart
H systems serving a population of at least ten thousand (10,000) individuals
may use these additional yearly disinfection profiles to develop a benchmark
under subsection (c). The commissioner shall determine whether these
operational data are substantially equivalent to data collected under
subdivision (2). These data must also be representative of inactivation through
the entire treatment plant and not just of certain treatment
segments.
(4) Subpart H
systems serving a population of at least ten thousand (10,000) individuals
shall calculate the total inactivation ratio as follows:
(A) If the system uses only one (1) point of
disinfectant application, the system may determine the total inactivation ratio
for the disinfection segment by using either of the following methods:
(i) Determine one (1) inactivation ratio
(CTcalc/CT99.9) before or at the first customer during
peak hourly flow.
(ii) Determine
successive CTcalc/CT99.9 values, representing sequential
inactivation ratios, between the point of disinfectant application and a point
before or at the first customer during peak hourly flow. Under this
alternative, the system must calculate the total inactivation ratio by
determining (CTcalc/CT99.9) for each sequence and then
adding the (CTcalc/CT99.9) values together to determine
(E (CTcalc/CT99.9)).
(B) Subpart H systems serving a population of
at least ten thousand (10,000) individuals that use more than one (1) point of
disinfectant application before the first customer shall determine the CT value
of each disinfection segment immediately prior to the next point of
disinfectant application, or for the final segment, before or at the first
customer, during peak hourly flow. The (CTcalc/CT99.9)
value of each segment and (E (CTcalc/CT99.9) shall be
calculated using the method in clause (A).
(C) Subpart H systems serving a population of
at least ten thousand (10,000) individuals shall determine the total logs of
inactivation by multiplying the value calculated in clause (A) or (B) by three
and zero-tenths (3.0).
(5) Subpart H systems serving a population of
at least ten thousand (10,000) individuals that use either chloramines or ozone
for primary disinfection shall also calculate the logs of inactivation for
viruses using a method approved by the commissioner.
(6) Subpart H systems serving a population of
at least ten thousand (10,000) individuals shall retain disinfection
profiledata in graphic form, as a spreadsheet, or in some other format
acceptable to the commissioner for review as part of sanitary surveys conducted
by the commissioner.
(c)
Disinfection benchmarking requirements are as follows:
(1) A Subpart H system serving a population
of at least ten thousand (10,000) individuals required to develop a
disinfection profile under subsections (a) and (b) that decides to make a
significant change to its disinfection practice shall consult with the
commissioner before making the change. As used in this subdivision,
"significant changes" means changes to the following:
(A) Point of disinfection.
(B) Disinfectants used in the treatment
plant.
(C) Disinfection
process.
(D) Any other modification
identified by the commissioner.
(2) A Subpart H system serving a population
of at least ten thousand (10,000) individuals that is modifying its
disinfection practice shall calculate its disinfection benchmark using the
following procedures:
(A) Subpart H systems
serving a population of at least ten thousand (10,000) individuals shall
determine the lowest average monthly Giardia lamblia inactivation for each year
of profiling data collected and calculated under subsection (b). The system
shall determine the average Giardia lamblia inactivation for each calendar
month for each year of profiling data by dividing the sum of daily Giardia
lamblia inactivation by the number of values calculated for that
month.
(B) The disinfection
benchmark is the lowest monthly average value (for Subpart H systems serving a
population of at least ten thousand (10,000) with one (1) year of profiling
data) or average of lowest monthly average values (for Subpart H systems
serving a population of at least ten thousand (10,000) individuals with more
than one (1) year of profiling data) of the monthly logs of Giardia lamblia
inactivation for each year of profiling data.
(C) Subpart H systems serving a population of
at least ten thousand (10,000) individuals that use either chloramines or ozone
for primary disinfection shall also calculate the disinfection benchmark for
viruses using a method approved by the commissioner.
(D) The system shall submit the following
information to the commissioner as part of its consultation process:
(i) A description of the proposed change in
disinfection practice.
(ii) The
disinfection profile for Giardia lamblia (and, if necessary, viruses) under
subsection (b) and benchmark as required by this subsection.
(iii) An analysis of how the proposed change
will affect the current levels of disinfection. * 40 CFR 141, 40 CFR 141.142,
40 CFR 141.142(b)(1), and 40 CFR 141.74(b) are incorporated by reference and
are available for copying at the Indiana Department of Environmental
Management, Office of Water Quality, 100 North Senate Avenue, Room N1255,
Indianapolis, Indiana 46204.
Notes
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