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

Current through June 24, 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 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.