Indiana Administrative Code
Title 327 - WATER POLLUTION CONTROL DIVISION
Article 8 - PUBLIC WATER SUPPLY
Rule 2.6 - Enhanced Filtration and Disinfection
Section 2.6-2.1 - Disinfection profiling and benchmarking for systems serving a population of fewer than 10,000 individuals beginning January 1, 2005
Universal Citation: 327 IN Admin Code 2.6-2.1
Current through September 18, 2024
Authority: IC 13-13-5-1; IC 13-14-8-7; IC 13-18-3-1; IC 13-18-3-2; IC 13-18-6
Affected: IC 13-14-9
Sec. 2.1.
(a) A disinfection profile is a graphical representation of a system's level of Giardia lamblia or virus inactivation measured during the course of a year. Beginning January 1, 2005, Subpart H systems serving a population of fewer than ten thousand (10,000) individuals must develop a disinfection profile unless the commissioner determines that the system's profile is unnecessary. The commissioner may approve the use of a more representative data set for disinfection profiling than the data set required under subsection (c).
(b) The commissioner may only determine that a system's profile is unnecessary if a system's TTHM and HAA5 levels are below sixty-four thousandths (0.064) mg/l and forty-eight thousandths (0.048) mg/l, respectively. To determine these levels, TTHM and HAA5 samples must be collected after January 1, 1998, during the month with the warmest water temperature and at the point of maximum residence time in a system's distribution system.
(c) Disinfection profiling requirements are as follows:
(1) A disinfection profile consists of three
(3) steps:
(A) Subpart H systems serving a
population of fewer than ten thousand (10,000) individuals must collect data
for several parameters from the plant over the course of twelve (12) months
according to subdivision (2). If the system serves more than five hundred (500)
and fewer than ten thousand (10,000) individuals, the system must begin to
collect data no later than July 1, 2003. If the system serves fewer than five
hundred (500) individuals, the system must begin to collect data no later than
January 1, 2004.
(B) The system
must use this data to calculate weekly log inactivation according to
subdivisions (3) and (4).
(C) The
system must use these weekly log inactivations to develop a disinfection
profile as specified in subdivisions (5) through (8).
(2) Subpart H systems serving a population of
fewer than ten thousand (10,000) individuals must monitor the following
parameters to determine the total log inactivation using the analytical methods
in
327
IAC 8-2-8.7, once per week on the same calendar day,
over twelve (12) consecutive months:
(A) The
temperature of the disinfected water at each residual disinfectant
concentration sampling point during peak hourly flow.
(B) If the system uses chlorine, the pH of
the disinfected water at each residual disinfectant concentration sampling
point during peak hourly flow.
(C)
The disinfectant contact time or times (T) during peak hourly flow.
(D) The residual disinfectant concentration
or concentrations (C) of the water before or at the first customer and prior to
each additional point of disinfection during peak hourly flow.
(3) Calculate the total
inactivation ratio using the following table and multiply the value by three
and zero-tenths (3.0) to determine log inactivation of Giardia lamblia:
| For systems that *** | The system must determine *** |
| (A) Use only one (1) point of disinfectant application | (i) One (1) inactivation ratio (CTcalc/CT99.9) before or at the first customer during peak hourly flow or (ii) 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, systems 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 (3CTcalc/CT99.9). |
| (B) Use more than one (1) point of disinfectant application before the first customer | The (CTcalc/CT99.9) 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 using the procedure specified in (A)(ii) of this table. |
(4)
Subpart H systems serving a population of fewer than ten thousand (10,000)
individuals that use chloramines, ozone, or chlorine dioxide for primary
disinfection must also calculate the logs of inactivation for viruses and
develop an additional disinfection profile for viruses using methods approved
by the commissioner.
(5) Develop a
disinfection profile by plotting each log inactivation as a data point. Systems
should have fifty-two (52) measurements to plot (one (1) for every week of the
year).
(6) Subpart H systems
serving a population of fewer than ten thousand (10,000) individuals and the
commissioner should evaluate the disinfection profile to examine microbial
inactivation variations over the course of the year by looking at all fifty-two
(52) measurements.
(7) Subpart H
systems serving a population of fewer than ten thousand (10,000) individuals
must retain the disinfection profiledata in graphic form, such as a
spreadsheet, that must be available for review by the commissioner as part of a
sanitary survey.
(8) Subpart H
systems serving a population of fewer than ten thousand (10,000) individuals
must use this data to calculate a benchmark if they are considering changes to
disinfection practices.
(d) Disinfection benchmark requirements are as follows:
(1) Subpart H systems serving a
population of fewer than ten thousand (10,000) individuals that are required to
develop a disinfection profile under subsections (a) through (c) must develop a
disinfection benchmark if a significant change is made to the system's
disinfection practices.
(2) Subpart
H systems serving a population of fewer than ten thousand (10,000) individuals
must consult with the commissioner for approval before implementing a
significant disinfection practice change. Significant changes to disinfection
practices include changes to the following:
(A) Point of disinfection.
(B) Disinfectant or disinfectants used in the
treatment plant.
(C) Disinfection
process.
(D) Any other modification
identified by the commissioner.
(3) Subpart H systems serving a population of
fewer than ten thousand (10,000) individuals that are considering a significant
change to their disinfection practices must calculate a disinfection benchmark
or benchmarks according to subdivisions (4) and (5) and provide the benchmark
or benchmarks to the commissioner. Subpart H systems serving a population of
fewer than ten thousand (10,000) individuals may make a significant
disinfection practice change only after consulting with the commissioner for
approval. Subpart H systems serving a population of fewer than ten thousand
(10,000) individuals must submit the following information to the commissioner
as part of the consultation and approval process:
(A) A description of the proposed
change.
(B) The disinfection
profile for Giardia lamblia (and, if necessary, viruses) and disinfection
benchmark.
(C) An analysis of how
the proposed change will affect the current levels of disinfection.
(D) Any additional information requested by
the commissioner.
(4)
Subpart H systems serving a population of fewer than ten thousand (10,000)
individuals that are making a significant change to their disinfection
practices must calculate a disinfection benchmark using the following
procedure:
(A) Using the data collected by the
system to develop the disinfection profile, determine 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.
(B) Determine the
lowest monthly average value out of the twelve (12) values. This value becomes
the disinfection benchmark. (5) Subpart H systems serving a population of fewer
than ten thousand (10,000) individuals and using chloramines, ozone, or
chlorine dioxide for primary disinfection must calculate the disinfection
benchmark from the data collected for viruses by the system to develop the
disinfection profile in addition to the Giardia lamblia disinfection benchmark
calculated under subdivision (4). This viral benchmark must be calculated in
the same manner used to calculate the Giardia lamblia disinfection benchmark in
subdivision (4).
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