Section 327IAC8-2-10.2. Monitoring frequency for radioactivity; community water systems

  2. (a) Monitoring requirements for gross alpha particle activity, radium-226, radium-228, and uranium in CWS are as follows:

(1) Initial monitoring requirements for CWSs are as follows:

(A) CWSs must conduct initial monitoring to determine compliance with section 9 of this rule by December 31, 2007. Unless exempted under subdivision (2) or reduced under clause (D), systems must collect four (4) consecutive quarterly samples at all sampling points before December 31, 2007.

(B) For the purposes of monitoring for gross alpha particle activity, radium-226, radium-228, and uranium in drinking water, "detection limit" is as described in section 10.1(c) of this rule.

(C) Applicability and sampling location shall be according to the following:

(i) Every existing CWS or source using ground water or surface water or a system using both ground and surface water (to be known as "system" for purposes of this section) must sample at every entry point to the distribution system that is representative of all sources being used (to be known as "sampling point" for purposes of this section) under normal operating conditions. The system must take each sample at the same sampling point unless conditions make another sampling point more representative of each source.

(ii) Every new CWS or source or CWS that uses a new source of water must conduct initial monitoring for the new source within the first quarter after initiating use of the source.

(iii) A system must conduct more frequent monitoring when ordered by the commissioner in the event of possible contamination or when changes in the distribution system or treatment processes occur that may increase the concentration of radioactivity in finished water.

(D) The commissioner may waive the final two (2) quarters of initial monitoring for a sampling point if the results of the samples from the previous two (2) quarters are below the detection limit.

(E) If the average of the initial monitoring results for a sampling point is above the MCL, the system must collect and analyze quarterly samples at that sampling point until the system has results from four (4) consecutive quarters that are at or below the MCL, unless the system enters into another schedule as part of a formal compliance agreement with the commissioner.

(2) The commissioner may allow historical monitoring data, that which is collected at a sampling point between June 1, 2000, and December 8, 2003, to satisfy the initial monitoring requirements for that sampling point in the following situations:

(A) A CWS having only one (1) entry point to the distribution system may use its acceptable historical monitoring data from the latest sampling conducted during the specified period.

(B) A CWS with multiple entry points and having appropriate historical monitoring data for each entry point to the distribution system may use the monitoring data from the latest sampling conducted during the specified period.

(3) Sampling after completion of the initial monitoring specified in subdivision (1) is once every three (3) years unless reduced by the commissioner as follows:

(A) If the average of the initial monitoring results for each contaminant (gross alpha particle activity, uranium, radium-226, or radium-228) is below the detection limit specified in section 10.1 of this rule, the system must collect and analyze for at least one (1) sample for that contaminant at that sampling point every nine (9) years.

(B) For gross alpha particle activity and uranium, if the average of the initial monitoring results for each contaminant is at or above the detection limit but at or below one-half (½) the MCL:

(i) the system must collect and analyze at least one (1) sample for that contaminant at that sampling point every six (6) years; and

(ii) for combined radium-226 and radium-228, the analytical results must be combined. If the average of the combined initial monitoring results for radium-226 and radium-228 is at or above the detection limit but at or below one-half (½) the MCL, the system must collect and analyze at least one (1) sample for radium-226 and radium-228 at that sampling point every six (6) years.

(C) Systems must use the samples collected during the most recent monitoring period to determine the monitoring frequency for subsequent monitoring periods. For example, if a system’s sampling point is on a nine (9) year monitoring period and the sample result is above one-half (½) the MCL, then the next monitoring period for that sampling point is three (3) years.

(D) If a system has a monitoring result that exceeds the MCL while sampling less frequently than quarterly, the system must collect and analyze quarterly samples at that sampling point until the system has results from four (4) consecutive quarters that are below the MCL unless the system enters into another schedule as part of a formal compliance agreement with the commissioner.

(4) To fulfill quarterly monitoring requirements for gross alpha particle activity, radium-226, radium-228, or uranium, a system may composite up to four (4) consecutive quarterly samples from a single entry point if analysis is done within one (1) year of the first sample. The commissioner will treat analytical results from the composited sample as the average analytical result to determine compliance with the MCLs and to determine the future monitoring frequency. If the analytical result from the composited sample is greater than one-half (½) the MCL, the commissioner may direct the system to take additional quarterly samples before allowing the system to sample once every three (3) years.

(5) A gross alpha particle activity measurement may be substituted for the required:

(A) radium-226 measurement provided that the measured gross alpha particle activity does not exceed five (5) pCi/l; and

(B) uranium measurement provided that the measured gross alpha particle activity does not exceed fifteen (15) pCi/l.

The gross alpha measurement shall have a confidence interval of ninety-five percent (95%) (1.65 σ, where σ is the standard deviation of the net counting rate of the sample) for radium-226 and uranium. When a system uses a gross alpha particle activity measurement instead of the measurement for radium-226 or uranium, or both, the gross alpha particle activity analytical result will be used to determine the future monitoring frequency for radium-226 or uranium, or both. If the gross alpha particle activity result is less than detection, one-half (½) the detection limit will be used to determine compliance and the future monitoring frequency.

  (b) For purposes of monitoring for beta particle and photon radioactivity in drinking water, "detection limit" is as described in section 10.1(c) of this rule. To determine compliance with the MCLs in section 10 of this rule for beta particle and photon radioactivity, a system must comply with monitoring and sampling frequency requirements as follows:

(1) CWSs (both surface and ground water) designated by the commissioner as vulnerable must sample for beta particle and photon radioactivity. Systems must collect quarterly samples for beta emitters and annual samples for tritium and strontium-90 at each sampling point beginning within one (1) quarter after being notified by the commissioner of the designation. Designated systems must continue to sample until the commissioner reviews and either reaffirms or removes the designation. If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity at a sampling point has a running annual average (computed quarterly) less than or equal to fifty (50) pCi/l (screening level), the commissioner may reduce the frequency of monitoring at that sampling point to once every three (3) years. A system must continue to collect all other samples required by this subdivision during the reduced monitoring period.

(2) CWSs (both surface and ground water) designated by the commissioner as utilizing waters contaminated by effluents from nuclear facilities must sample for beta particle and photon radioactivity. A system designated under this subdivision must collect quarterly samples for beta emitters and iodine-131 and annual samples for tritium and strontium-90 at each entry point to the distribution system beginning within one (1) quarter after being notified by the commissioner of the designation. A system designated as using waters contaminated by effluents from a nuclear facility must continue to sample until the commissioner reviews and either reaffirms or removes the designation. The following monitoring and frequency of sampling requirements apply to vulnerable systems:

(A) Quarterly monitoring for gross beta particle activity shall be based on the analysis of monthly samples or the analysis of a composite of three (3) monthly samples. The former is recommended.

(B) For iodine-131, a composite of five (5) consecutive daily samples shall be analyzed once each quarter. At the direction of the commissioner, more frequent monitoring shall be conducted when iodine-131 is identified in the finished water.

(C) Annual monitoring for strontium-90 and tritium shall be conducted by analysis of a composite of four (4) consecutive quarterly samples or analysis of four (4) quarterly samples. The latter procedure is recommended.

(D) If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity at a sampling point has a running annual average (computed quarterly) less than or equal to fifteen (15) pCi/l (screening level), the commissioner may reduce the frequency of monitoring at that sampling point to once every three (3) years. Systems must collect all samples required in this subdivision during the reduced monitoring period.

(3) CWSs may analyze for naturally occurring potassium-40 beta particle activity from the same or equivalent sample used for the gross beta particle activity analysis. Systems are allowed to subtract the potassium-40 beta particle activity value from the total gross beta particle activity value to determine if the screening level is exceeded. The potassium-40 beta particle activity must be calculated by multiplying elemental potassium concentrations (in mg/l) by a factor of eighty-two hundredths (0.82).

(4) If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity exceeds the appropriate screening level, an analysis of the sample must be performed to identify the major radioactive constituents present in the sample and the appropriate doses must be calculated and summed to determine compliance with section 10 of this rule using the formula in that section. Doses must be calculated and combined for measured levels of major radioactive constituents, tritium, and strontium to determine compliance.

(5) A system must monitor monthly at the sampling point or points that exceed the MCL in section 10 of this rule beginning the month after the exceedance occurs. A system must continue monthly monitoring until the system has established, by a rolling average of three (3) monthly samples, that the MCL is being met. A system that reestablishes compliance with the MCL must return to quarterly monitoring until the requirements set forth in subdivision (1) or (2)(D) are met.

  (c) The following general monitoring and compliance requirements for radionuclides apply:

(1) The commissioner has the discretion to require:

(A) more frequent monitoring than specified in subsections (a) and (b); or

(B) confirmation samples.

The results of the initial and confirmation samples shall be averaged for use in compliance determinations.

(2) A CWS shall monitor at the time designated by the commissioner during each compliance period.

(3) The following shall be used to determine whether a CWS is in compliance with sections 9 through 10 of this rule:

(A) Analytical results obtained at each sampling point must meet the applicable requirements of sections 9 through 10 of this rule. If one (1) sampling point is in violation of an MCL, the system is in violation of the MCL.

(B) For systems monitoring more than once per year, compliance with the MCL is determined by a running annual average at each sampling point. If the running annual average of any sampling point is greater than the MCL, then the system is out of compliance with the MCL.

(C) For systems monitoring more than once per year, if any single sample result will cause the running average to exceed the MCL at any sample point, the system is out of compliance with the MCL immediately.

(D) A system must include all samples taken and analyzed under this section in determining compliance even if that number is greater than the minimum required.

(E) If a system does not collect all required samples when compliance with the MCL is based on a running annual average of quarterly samples, compliance will be based on the running average of the samples collected.

(F) If a sample result is less than the detection limit, zero (0) shall be used to calculate the annual average, unless a gross alpha particle activity is being used instead of radium-226 or uranium, or both. If the gross alpha particle activity result is less than detection, one-half (½) the detection limit will be used to calculate the annual average.

(4) The commissioner has the discretion to delete results of obvious sampling or analytic errors.

(5) If the MCL for radioactivity set forth in sections 9 through 10 of this rule is exceeded, the operator of a CWS must give notice to the commissioner under section 13 of this rule and to the public as required by 327 IAC 8-2.1-7 through 327 IAC 8-2.1-16.

(Water Pollution Control Division; 327 IAC 8-2-10.2; filed Dec 28, 1990, 5:10 p.m.: 14 IR 1029; errata filed Aug 6, 1991, 3:45 p.m.: 14 IR 2258; filed Nov 20, 2001, 10:20 a.m.: 25 IR 1094; errata filed Feb 22, 2002, 2:01 p. m.: 25 IR 2254; filed Jun 13, 2005, 2:30 p.m.: 28 IR 3212; errata filed Jul 6, 2005, 3:15 p.m.: 28 IR 3582)