Section 327IAC8-2.6-2.1. Disinfection profiling and benchmarking for systems serving a population of fewer than 10,000 individuals beginning January 1, 2005

  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 profile data 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).

(Water Pollution Control Division; 327 IAC 8-2.6-2.1; filed Jun 13, 2005, 2:30 p.m.: 28 IR 3250; errata filed Jul 6, 2005, 3:15 p.m.: 28 IR 3583)