NR 809.53(1)(e)(e) Compositing. To fulfill quarterly monitoring requirements for gross alpha particle activity, radium-226, radium-228 or uranium, a water supplier for a community water system may composite up to 4 consecutive quarterly samples from a single entry point if analysis is done within a year of the first sample. The department will treat analytical results from the composited results as the average analytical result to determine compliance with the MCLs and the future monitoring frequency. If the analytical result from the composited sample is greater than one-half the MCL, the department may direct the water supplier to take additional quarterly samples before allowing the water supplier to sample under a reduced monitoring schedule.

NR 809.53(1)(f)(f) Gross alpha particle activity measurement substitutions. A gross alpha particle activity measurement may be substituted for the required radium-226 measurement provided that the measured gross alpha particle activity does not exceed 5 pCi/l. A gross alpha particle activity measurement may be substituted for the required uranium measurement provided that the measured gross alpha particle activity does not exceed 15 pCi/l. The gross alpha measurement shall have a confidence interval of 95% confidence level, 1.65 ó where ó is the standard deviation of the net counting rate of the sample for radium-226 and uranium. When a water supplier for a community water system uses a gross alpha particle activity measurement in lieu of a measurement for radium-226 or uranium, or both, the gross alpha particle activity analytical result shall 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 the detection limit shall be used to determine compliance and the future monitoring frequency.

NR 809.53(2)(2) Monitoring requirements for beta particle and photon radioactivity. To determine compliance with the maximum contaminant levels in s. NR 809.51 for beta particle and photon radioactivity, a water supplier for a community water system shall monitor at a frequency as follows:

NR 809.53(2)(a)(a) Community water systems designated by the department as vulnerable, shall be sampled for beta particle and photon radioactivity. Water suppliers for community water systems shall collect quarterly samples for beta emitters and annual samples for tritium and strontium-90 at each entry point to the distribution system, no later than one quarter after being notified by the department. Community water systems already designated by the department shall continue to be sampled until the department reviews and either reaffirms or removes the designation.

NR 809.53(2)(a)1.1. If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity at an entry point has a running annual average, computed quarterly, less than or equal to 50 pCi/l, the department may reduce the frequency of monitoring at that entry point to once every 3 years. Water suppliers for community water systems shall collect all samples required in this subsection during the reduced monitoring period.

NR 809.53(2)(a)2.2. For community water systems in the vicinity of a nuclear facility, the department may allow the water supplier for the community water system to utilize environmental surveillance data collected by the nuclear facility in lieu of monitoring at the community water system’s entry points, if the department determines that the data is applicable to a particular community water system. If there is a release from a nuclear facility, water suppliers for community water systems which are using surveillance data shall begin monitoring at the community water system’s entry points in accordance with this subsection.

NR 809.53(2)(b)(b) Water suppliers for community water systems designated by the department as utilizing waters contaminated by effluents from nuclear facilities shall sample for beta particle and photon radioactivity. Water suppliers shall 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 no later than one quarter after being notified by the department. Water suppliers for community water systems already designated by the department as community water systems using water contaminated by effluents from nuclear facilities shall continue to sample until the department reviews and either reaffirms or removes the designation.

NR 809.53(2)(b)2.2. For iodine-131, a composite of 5 consecutive daily samples shall be analyzed once each quarter. As ordered by the department, more frequent monitoring shall be conducted when iodine-131 is identified in the finished water.

NR 809.53(2)(b)4.4. 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 15 pCi/l, the department may reduce the frequency of monitoring at that sampling point to once every 3 years. Water suppliers for community water systems shall collect all samples required in this paragraph during the reduced monitoring period.

NR 809.53(2)(b)5.5. For community water systems in the vicinity of a nuclear facility, the department may allow the water supplier for community water system to utilize environmental surveillance data collected by the nuclear facility in lieu of monitoring at the community water system’s entry points, if the department determines that the data is applicable to a particular community water system. If there is a release from a nuclear facility, water suppliers for community water systems which are using surveillance data shall begin monitoring at the community water system’s entry points in accordance with this paragraph.

NR 809.53(2)(c)(c) Water suppliers for community water systems designated by the department to monitor for beta particle and photon radioactivity may not apply to the department for a waiver from the monitoring frequencies specified in either par. (a) or (b).

NR 809.53(2)(d)(d) Water suppliers for community water systems may analyze for naturally occurring potassium-40 beta particle activity from the same or equivalent sample used for the gross beta particle activity analysis. Water suppliers for community water systems may subtract the potassium-40 beta particle activity value from the total gross beta particle activity value to determine if 50 pCi/l is exceeded. The potassium-40 beta particle activity shall be calculated by multiplying elemental potassium concentrations, in mg/l, by a factor of 0.82.

NR 809.53(2)(e)(e) If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity exceeds 50 pCi/l, an analysis of the sample shall be performed to identify the major radioactive constituents present in the sample and the appropriate doses shall be calculated and summed to determine compliance with s. NR 809.51 (1) using the formula in s. NR 809.51 (2). Doses shall also be calculated and combined for measured levels of tritium and strontium to determine compliance.

NR 809.53(2)(f)(f) Water suppliers for community water systems shall monitor monthly at the sampling points that exceed the maximum contaminant level in s. NR 809.51 beginning the month after the exceedance occurs. Water suppliers shall continue monthly monitoring until the water supplier has established, by a rolling average of 3 monthly samples, that the MCL is being met. Water suppliers for community water systems that establish that the MCL is being met shall return to quarterly monitoring until the requirements in par. (a) 1. or (b) 4. are met.

NR 809.53(3)(a)(a) The department may require more frequent monitoring than specified in subs. (1) and (2), or may require confirmation samples at its discretion. The results of the initial and confirmation samples shall be averaged for use in compliance determinations.

NR 809.53(3)(b)(b) Water suppliers for each public water system shall monitor at the time designated by the department during each compliance period.

NR 809.53(3)(c)(c) Compliance with ss. NR 809.50 (1) and 809.51 (1) shall be determined based on the analytical results obtained at each sampling point. If one sampling point is in violation of an MCL, the community water system is in violation of the MCL. In addition:

NR 809.53(3)(c)1.1. For community water systems monitored more than once per year, compliance with the MCL is determined by using a running annual average calculated for each sampling point. If the average of any sampling point is greater than the MCL, the community water system is out of compliance with the MCL.

NR 809.53(3)(c)2.2. For community water systems monitored more than once per year, if any sample result will cause the running annual average to exceed the MCL at any sample point, the community water system is out of compliance with the MCL immediately.

NR 809.53(3)(c)3.3. For community water systems on reduced monitoring where monitoring results exceed an MCL, and a community water system is placed on quarterly monitoring as required by sub. (1) (d) 5., compliance with the MCL is determined based on a running annual average at each sample point, as required by sub. (3) (c) 1. if sample results exceed the MCL.

NR 809.53(3)(c)5.5. If a water supplier for a community water system does not collect all required samples when compliance is based on a running annual average of quarterly samples, compliance shall be based on the running average of the samples collected.

NR 809.53(3)(c)6.6. If a sample result is less than the detection limit, zero will be used to calculate the annual average, unless a gross alpha particle activity is being used in lieu of radium-226 or uranium, or both. If the gross alpha particle activity result is less than detection, 1/2 the detection limit shall be used to calculate the annual average.