Section 327IAC8-2.5-6. Monitoring requirements; disinfectant residuals, disinfection byproducts, and disinfection byproducts precursors

   (a) General monitoring requirements for disinfectant residuals, disinfection byproducts, and disinfection byproducts precursors are as follows:

(1) Systems shall take all samples during normal operating conditions.

(2) Systems may consider multiple wells drawing water from a single aquifer as one (1) treatment plant for determining the minimum number of TTHM and HAA5 samples required. The commissioner shall approve all instances of multiple wells that are considered a single treatment plant because they draw water from a single aquifer.

(3) Failure to monitor:

(A) in accordance with the monitoring plan required under subsection (f) is a monitoring violation; and

(B) will be treated as a violation for the entire period covered by the annual average where compliance is based on a running annual average of monthly or quarterly samples or averages and the system's failure to monitor makes it impossible to determine compliance with MCLs or MRDLs.

(4) Systems may use only data collected under the provisions of subsection (b) or 40 CFR 141.140 through 40 CFR 141.144* to qualify for reduced monitoring.

  (b) Monitoring requirements for disinfection byproducts are as follows:

(1) TTHM and HAA5 monitoring requirements are as follows:

(A) For routine monitoring, systems shall monitor at the frequency indicated in the following table:

ROUTINE MONITORING FREQUENCY FOR TTHM AND HAA5
Type of System	Minimum Monitoring Frequency	Sample Location in the Distribution System
Subpart H system serving at least 10,000 persons	4 water samples per quarter per treatment plant	At least 25% of all samples collected each quarter at locations representing maximum residence time. Remaining samples taken at locations representative of at least average residence time in the distribution system and representing the entire distribution system, taking into account number of persons served, different sources of water, and different treatment methods1.
Subpart H system serving from 500 to 9,999 persons	1 water sample per quarter per treatment plant	Locations representing maximum residence time1.
Subpart H system serving fewer than 500 persons	1 sample per year per treatment plant during month of warmest water temperature	Locations representing maximum residence time1. If the sample (or average of annual samples, if more than one sample is taken) exceeds the MCL, the system shall increase monitoring to 1 sample per treatment plant per quarter, taken at a point reflecting the maximum residence time in the distribution system, until the system meets reduced monitoring criteria in clause (D).
System using only ground water not under direct influence of surface water using chemical disinfectant and serving at least 10,000 persons	1 water sample per quarter per treatment plant2	Locations representing maximum residence time1.
System using only ground water not under direct influence of surface water using chemical disinfectant and serving fewer than 10,000 persons	1 sample per year per treatment plant2 during month of warmest water temperature	Locations representing maximum residence time1. If the sample (or average of annual samples, if more than 1 sample is taken) exceeds the MCL, the system shall increase monitoring to 1 sample per treatment plant per quarter, taken at a point reflecting the maximum residence time in the distribution system, until the system meets criteria in clause (D) for reduced monitoring.

¹If a system elects to sample more frequently than the minimum required, at least twenty-five percent (25%) of all samples collected each quarter, including those taken in excess of the required frequency, must be taken at locations that represent the maximum residence time of the water in the distribution system. The remaining samples must be taken at locations representative of at least average residence time in the distribution system.

²Multiple wells drawing water from a single aquifer may be considered one (1) treatment plant for determining the minimum number of samples required.

(B) Systems may reduce monitoring, except as otherwise provided, in accordance with the following table:

REDUCED MONITORING FREQUENCY FOR TTHM AND HAA5
IF YOU ARE A:	AND YOU HAVE MONITORED AT LEAST ONE YEAR AND YOUR:	YOU MAY REDUCE MONITORING TO THIS LEVEL:
Subpart H system serving at least 10,000 persons that has a source water annual average TOC level, before any treatment, ≤ 4.0 mg/L	TTHM annual average ≤ 0.040 mg/L and HAA5 annual average ≤0.030 mg/L	1 sample per treatment plant per quarter at distribution system location reflecting maximum residence time
Subpart H system serving from 500 to 9,999 persons that has a source water annual average TOC level, before any treatment, ≤ 4.0 mg/L	TTHM annual average ≤ 0.040 mg/L and HAA5 annual average ≤0.030 mg/L	1 sample per treatment plant per year at distribution system location reflecting maximum residence time during month of warmest water temperature. NOTE: Any Subpart H system serving fewer than 500 persons may not reduce its monitoring to less than 1 sample per treatment plant per year.
System using only ground water not under direct influence of surface water using chemical disinfectant and serving at least 10,000 persons	TTHM annual average ≤ 0.040 mg/L and HAA5 annual average ≤0.030 mg/L	1 sample per treatment plant per year at distribution system location reflecting maximum residence time during month of warmest water temperature
System using only ground water not under direct influence of surface water using chemical disinfectant and serving fewer than 10,000 persons	TTHM annual average ≤0.040 mg/L and HAA5 annual average ≤0.030 mg/L for 2 consecutive years or TTHM annual average ≤0.020 mg/L and HAA5 annual average ≤0.015 mg/L for 1 year	1 sample per treatment plant per 3 year monitoring cycle at distribution system location reflecting maximum residence time during month of warmest water temperature, with the 3 year cycle beginning on January 1 following quarter in which system qualifies for reduced monitoring

(C) Beginning April 1, 2008, or earlier if specified by the commissioner, in order to qualify for reduced monitoring for TTHM and HAA5 under clause (B), Subpart H systems not monitoring under the provisions of subsection (d), shall meet the following requirements:

(i) Take monthly TOC samples every thirty (30) days at a location before any treatment.

(ii) In addition to meeting other criteria for reduced monitoring in clause (B), the source water TOC running annual average must be less than or equal to four and zero-tenths (4.0) milligrams per liter (based on the most recent four (4) quarters of monitoring) on a continuing basis at each treatment plant to reduce or remain on reduced monitoring for TTHM and HAA5.

(iii) Once qualified for reduced monitoring for TTHM and HAA5 under clause (B), a system may reduce source water TOC monitoring to quarterly TOC samples taken every ninety (90) days at a location before any treatment.

(D) Systems on a reduced monitoring schedule shall comply with the following:

(i) Systems may remain on the reduced schedule as long as the:

(AA) average of all samples taken in the year (for systems that must monitor quarterly); or

(BB) result of the sample (for systems that must monitor not more frequently than annually);

is not more than sixty-thousandths (0.060) milligram per liter and forty-five thousandths (0.045) milligram per liter for TTHMs and HAA5, respectively.

(ii) Systems that do not meet the levels specified under item (i) shall resume monitoring at the frequency identified in the table contained in clause (A) (minimum monitoring frequency column) in the quarter immediately following the monitoring period in which the system exceeds those levels.

(iii) For systems using only ground water not under the direct influence of surface water and serving fewer than ten thousand (10,000) persons, if either the:

(AA) TTHM annual average is greater than eighty-thousandths (0.080) milligram per liter; or

(BB) HAA5 annual average is greater than sixty-thousandths (0.060) milligram per liter;

the system shall go to the increased monitoring identified in the table contained in clause (A) (sample location column) in the quarter immediately following the monitoring period in which the system exceeds those levels.

(E) Systems on increased monitoring may return to routine monitoring if, after at least one (1) year of monitoring, their:

(i) TTHM annual average is equal to or less than sixty-thousandths (0.060) milligram per liter; and

(ii) HAA5 annual average is equal to or less than forty-five thousandths (0.045) milligram per liter.

(F) A system may return to routine monitoring at the commissioner's discretion.

(2) CWSs and NTNCWSs using chlorine dioxide for disinfection or oxidation must conduct monitoring for chlorite as follows:

(A) Routine monitoring is as follows:

(i) Systems shall take daily samples at the entrance to the distribution system. For any daily sample that exceeds the chlorite MCL, the system shall take additional samples in the distribution system the following day at the locations required by clause (B), in addition to the sample required at the entrance to the distribution system.

(ii) Systems shall take a three (3) sample set each month in the distribution system. The system shall take one (1) sample at each of the following locations:

(AA) Near the first customer.

(BB) At a location representative of average residence time.

(CC) At a location reflecting maximum residence time in the distribution system.

Any additional routine sampling must be conducted in the same manner (as three (3) sample sets, at the specified locations). The system may use the results of additional monitoring conducted under clause (B) to meet the requirement for monitoring in this clause.

(B) On each day following a routine sample monitoring result that exceeds the chlorite MCL at the entrance to the distribution system, the system shall take three (3) chlorite distribution system samples at the following locations:

(i) As close to the first customer as possible.

(ii) In a location representative of average residence time.

(iii) As close to the end of the distribution system as possible at a point reflecting maximum residence time in the distribution system.

(C) Monitoring for chlorite may be reduced as follows:

(i) Chlorite monitoring at the entrance to the distribution system required by clause (A)(i) may not be reduced.

(ii) Chlorite monitoring in the distribution system required by clause (A)(ii) applies as follows:

(AA) Chlorite monitoring may be reduced to one (1) three (3) sample set per quarter after one (1) year of monitoring where no individual chlorite sample taken in the distribution system under clause (A)(ii) has exceeded the chlorite MCL and the system has not been required to conduct monitoring under clause (B).

(BB) The system may remain on the reduced monitoring schedule specified under subitem (AA) unless one (1) of the three (3) individual chlorite samples taken monthly in the distribution system under clause (A)(ii) exceeds the chlorite MCL or the system is required to conduct monitoring under clause (B), at which time the system shall revert to routine monitoring.

(3) Monitoring for bromate is as follows:

(A) CWSs and NTNCWSs using ozone for disinfection or oxidation shall take:

(i) one (1) sample per month for each treatment plant in the system using ozone; and

(ii) the samples required under item (i) monthly at the entrance to the distribution system while the ozonation system is operating under normal conditions.

(B) Until March 31, 2009, systems required to analyze for bromate may reduce monitoring from monthly to quarterly under the following conditions:

(i) The system demonstrates that the average source water bromide concentration is less than five-hundredths (0.05) milligram per liter based upon representative monthly bromide measurements for one (1) year.

(ii) The system may remain on reduced bromate monitoring unless the running annual average source water bromide concentration, computed quarterly, is equal to or greater than five-hundredths (0.05) milligram per liter based upon representative monthly measurements.

(iii) If the running annual average source water bromide concentration is equal to or greater than five-hundredths (0.05) milligram per liter, the system shall resume routine monitoring required by clause (A) in the month following the result.

(C) Beginning April 1, 2009, a system may no longer use the provisions of clause (B) to qualify for reduced monitoring but may be eligible for reduced monitoring according to the following:

(i) A system required to analyze for bromate may reduce monitoring from monthly to quarterly, if the system's running annual average bromate concentration is less than or equal to twenty-five ten-thousandths (0.0025) milligrams per liter based on monthly bromate measurements under clause (A) for the most recent four (4) quarters, with samples analyzed using EPA Method 317.0, Revision 2.0, EPA Method 326.0, or EPA Method 321.8.

(ii) If a system has qualified for reduced bromate monitoring under clause (B), that system may remain on reduced monitoring as long as the running annual average of quarterly bromate samples is less than or equal to twenty-five ten-thousandths (0.0025) milligrams per liter based on samples analyzed using EPA Method 317.0, Revision 2.0, EPA Method 326.0, or EPA Method 321.8.

(iii) If the running annual average bromate concentration is greater than twenty-five ten-thousandths (0.0025) milligrams per liter, the system shall resume routine monitoring required by clause (A)(i).

  (c) Monitoring requirements for disinfectant residuals are as follows:

(1) Monitoring for chlorine and chloramines is as follows:

(A) CWSs and NTNCWSs that use chlorine or chloramines shall comply with the following:

(i) The systems shall measure the residual disinfectant level in the distribution system at the same points and at the same time as total coliforms are sampled, as specified in 327 IAC 8-2-8.

(ii) Subpart H systems may use the results of residual disinfectant concentration sampling conducted under 327 IAC 8-2-8.8(d) for systems that filter instead of taking separate samples.

(B) Monitoring for chlorine or chloramines may not be reduced.

(2) Monitoring for chlorine dioxide is as follows:

(A) CWSs, NTNCWSs, and TWSs that use chlorine dioxide for disinfection or oxidation shall comply with the following:

(i) The systems shall take daily samples at the entrance to the distribution system.

(ii) For any daily sample that exceeds the MRDL, the system shall take samples in the distribution system the following day at the locations required by clause (B) in addition to the sample required at the entrance to the distribution system.

(B) On each day following a routine sample monitoring result that exceeds the MRDL, the system is required to take three (3) chlorine dioxide distribution system samples as follows:

(i) If chlorine dioxide or chloramines are used to maintain a disinfectant residual in the distribution system, or if chlorine is used to maintain a disinfectant residual in the distribution system and there are no disinfection addition points after the entrance to the distribution system, for example, no booster chlorination, the system shall take three (3) samples as close to the first customer as possible at intervals of at least six (6) hours.

(ii) If chlorine is used to maintain a disinfectant residual in the distribution system and there are one (1) or more disinfection addition points after the entrance to the distribution system, for example, booster chlorination, the system shall take one (1) sample at each of the following locations:

(AA) As close to the first customer as possible.

(BB) In a location representative of average residence time.

(CC) As close to the end of the distribution system as possible, reflecting maximum residence time in the distribution system.

(C) Chlorine dioxide monitoring may not be reduced.

  (d) Monitoring requirements for disinfection byproduct precursors (DBPP) are as follows:

(1) Routine monitoring is required as follows:

(A) Subpart H systems that use conventional filtration treatment, as defined in 327 IAC 8-2-1, shall monitor each treatment plant for TOC not later than the point of combined filter effluent turbidity monitoring and representative of the treated water.

(B) All systems required to monitor under this subdivision shall also monitor for TOC in the source water before any treatment at the same time as monitoring for TOC in the treated water. These samples, source water and treated water, are referred to as paired samples.

(C) At the same time as the source water sample is taken, all systems shall monitor for alkalinity in the source water before any treatment.

(D) Systems shall take one (1) paired sample and one (1) source water alkalinity sample per month per plant at a time representative of normal operating conditions and influent water quality.

(2) Subpart H systems with an average treated water TOC of less than:

(A) two and zero-tenths (2.0) milligrams per liter for two (2) consecutive years; or

(B) one and zero-tenths (1.0) milligram per liter for one (1) year;

may reduce monitoring for both TOC and alkalinity to one (1) paired sample and one (1) source water alkalinity sample per plant per quarter. The system shall revert to routine monitoring in the month following the quarter when the annual average treated water TOC is greater than or equal to two and zero-tenths (2.0) milligrams per liter.

  (e) Systems required to analyze for bromate may reduce bromate monitoring from monthly to once per quarter if the system demonstrates that the average source water bromide concentration is less than five-hundredths (0.05) milligram per liter based upon representative monthly measurements for one (1) year. The system shall continue bromide monitoring to remain on reduced bromate monitoring.

  (f) Each system required to monitor under this section shall develop and implement a monitoring plan as follows:

(1) The system shall maintain the plan and make it available for inspection by the commissioner and the general public not later than thirty (30) days following the applicable compliance dates in section 4(b) and 4(c) of this rule.

(2) All Subpart H systems serving more than three thousand three hundred (3,300) people shall submit a copy of the monitoring plan to the commissioner not later than the date of the first report required under section 8 of this rule.

(3) The commissioner may also require any other system to submit a monitoring plan.

(4) After review, the commissioner may require changes in any plan elements.

(5) The plan must include, at a minimum, the following elements:

(A) Specific locations and schedules for collecting samples for any parameters included in this section.

(B) How the system will calculate compliance with MCLs, MRDLs, and treatment techniques.

(C) If:

(i) approved for monitoring as a consecutive system; or

(ii) providing water to a consecutive system;

the sampling plan must reflect the entire distribution system.

  *40 CFR 141.140 through 40 CFR 141.144 is incorporated by reference and is available for copying at the Indiana Department of Environmental Management, Office of Water Quality, 100 North Senate Avenue, Room N1255, Indianapolis, Indiana 46204. (Water Pollution Control Division; 327 IAC 8-2.5-6; filed May 1, 2003, 12:00 p.m.: 26 IR 2844; errata filed Feb 6, 2006, 11:15 a.m.: 29 IR 1937; filed Oct 24, 2006, 3:03 p.m.: 20061122-IR-327050255FRA; errata filed Dec 6, 2006, 10:10 a.m.: 20061227-IR-327050255ACA; filed May 7, 2010, 9:30 a.m.: 20100602-IR-327080198FRA)