Wisconsin Administrative Code
Department of Natural Resources
NR 800 - Environmental Protection - Water Supply
Chapter NR 809 - Safe Drinking Water
Subchapter I - Maximum Contaminant Levels, Monitoring and Analytical Requirements for Primary Drinking Water Contaminants
Section NR 809.53 - Radionuclide monitoring frequency and compliance requirements for community water systems

Universal Citation: WI Admin Code § NR 809.53

Current through August 26, 2024

(1) MONITORING REQUIREMENTS FOR GROSS ALPHA PARTICLE ACTIVITY, RADIUM-226, RADIUM-228 AND URANIUM.

(a) Detection limits. For the purposes of monitoring for gross alpha particle activity, radium-226, radium-228, uranium and beta particle and photon radioactivity in drinking water, "detection limit" is defined in s. NR 809.52(4).

(b) Applicability and sampling location. Community water system applicability and sampling location requirements shall be as follows:

1. Applicability and sampling location for existing community water systems or sources. All water suppliers for existing community water systems shall sample at every entry point to the distribution system that is representative of all sources being used, under normal operating conditions. The water supplier shall take each sample at the same location unless conditions make another location more representative of each source or the department has designated a distribution system location, in accordance with par. (c) 2. c.

2. Applicability and sampling location for new community water systems or sources. Water suppliers for all new community water systems or community water systems that use a new source of water shall begin to conduct initial monitoring for the new source within the first quarter after initiating use of the source. Water suppliers shall conduct more frequent monitoring when ordered by the department in the event of possible contamination or when changes in the distribution system or treatment processes occur which may increase the concentration of radionuclides in finished water.

(c) Initial monitoring. Water suppliers for community water systems shall conduct initial monitoring for gross alpha particle activity, radium-226, radium-228 and uranium as follows:

1. Except as provided in subd. 2., water suppliers shall collect 4 consecutive quarterly samples at all sampling points before December 31, 2007.

2. As an alternative to the requirement of subd. 1., water suppliers may use historical monitoring data collected at a sampling point to satisfy the initial monitoring requirements for that sampling point for the following situations:

a. To satisfy initial monitoring requirements, a water supplier for a community water system having only one entry point to the distribution system may use the monitoring data from the last compliance monitoring period that began between June 1, 2000 and December 8, 2003.

b. To satisfy initial monitoring requirements, a water supplier for a community water system 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 last compliance monitoring period that began between June 1, 2000 and December 8, 2003.

c. To satisfy initial monitoring requirements, a water supplier for a community water system with appropriate historical data for a representative point in the distribution system may use the monitoring data from the last compliance monitoring period that began between June 1, 2000 and December 8, 2003, provided that the department finds that the historical data satisfactorily demonstrate that each entry point to the distribution system is expected to be in compliance based upon the historical data and reasonable assumptions about the variability of contaminant levels between entry points. The department shall make a written finding indicating how the data conforms to these requirements.

3. For gross alpha particle activity, uranium, radium-226 and radium-228 monitoring, the department may waive the final 2 quarters of initial monitoring for a sampling point if the results of the samples from the previous 2 quarters are below the detection limit.

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

(d) Reduced monitoring. Upon completion of initial monitoring the department may allow monitoring once every 3 years, once every 6 years, or once every 9 years, for each sampling point based on the following criteria:

1. If the average of the initial monitoring results for each contaminant, i.e., gross alpha particle activity, uranium, radium-226 or radium-228, is below the detection limit specified in s. NR 809.52(2), Table O, the water supplier for a community water system shall collect and analyze for that contaminant using at least one sample at that sampling point every 9 years.

2. 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 the MCL, the water supplier for a community water system shall collect and analyze for that contaminant using at least one sample at that sampling point every 6 years. For combined radium-226 and radium-228, the analytical results shall 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 the MCL, the water supplier for a community water system shall collect and analyze for that contaminant using at least one sample at that sampling point every 6 years.

3. For gross alpha particle activity and uranium, if the average of the initial monitoring results for each contaminant is above one-half the MCL but at or below the MCL, the water supplier for a community water system shall collect and analyze at least one sample at that sampling point every 3 years. For combined radium-226 and radium-228, the analytical results shall be combined. If the average of the combined initial monitoring results for radium-226 and radium-228 is above one-half the MCL, but at or below the MCL, the water supplier for a community water system shall collect and analyze at least one sample at that sampling point every 3 years.

4. Results of samples collected during a reduced monitoring period shall be used to determine the monitoring frequency for subsequent monitoring periods.

5. If a community water system has a monitoring result that exceeds the MCL while on reduced monitoring, the water supplier for a community water system shall collect and analyze quarterly samples at that sampling point until the community water system has results from 4 consecutive quarters that are below the MCL, unless the water supplier for a community water system enters into another schedule as part of a formal compliance agreement with the department.

(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.

(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 Ã³ where Ã³ 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.

(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:

(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.

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.

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.

3. At the discretion of the department, water suppliers for the community water systems utilizing only groundwater may be required to monitor for manmade radioactivity.

(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.

1. Quarterly monitoring for gross beta particle activity shall be based on the analysis of monthly samples or the analysis of a composite of 3 monthly samples.

Note: Quarterly monitoring for gross beta particle activity based on the analysis of monthly samples is recommended.

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.

3. Annual monitoring for strontium-90 and tritium shall be conducted by means of the analysis of a composite of 4 consecutive quarterly samples or analysis of 4 quarterly samples.

Note: Annual monitoring for strontium-90 and tritium by means of the analysis of a composite of 4 consecutive quarterly samples is recommended.

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.

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.

(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).

(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.

(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.

(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.

(3) GENERAL MONITORING AND COMPLIANCE REQUIREMENTS FOR RADIONUCLIDES.

(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.

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

(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:

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.

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.

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.

4. Water suppliers for community water systems shall include all samples taken and analyzed under this section in determining compliance, even if that number is greater than the minimum required.

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.

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.

(d) The department may delete results of obvious sampling or analytic errors.

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