11 Natural uranium and thorium-230 or approved as gross alpha calibration standards for gross alpha with co-precipitation and evaporation methods, americium-241 is approved with co-precipitation methods.

12 If uranium (U) is determined by mass a 0.67 pCi/g of uranium conversion factor shall be used. This conservative factor is based on the 1:1 activity ratio of U-234 to U-238 that is characteristic of naturally occurring uranium.

NR 809.52(3)(3) Results rounding. To judge compliance with the maximum contaminant levels listed in s. NR 809.50, averages of data shall be used and shall be rounded to the same number of significant figures as the maximum contaminant level for the substance in question.

NR 809.52(4)(4) Sensitivity limits. For the purpose of monitoring radionuclide concentrations in drinking water, the required sensitivity of the radioanalysis is defined in terms of a detection limit. The detection limit shall be that concentration which can be counted with a precision of plus or minus 100% at the 95% confidence level, 1.96 ó where ó is the standard deviation of the net counting rate of the sample.

NR 809.52(5)(5) Detection limits for man-made beta particle and photon emitters. To determine compliance with s. NR 809.51, the detection limits may not exceed the concentrations listed in Table P.

NR 809.52 NoteNote: Sections NR 809.50 to 809.52 are identical to the radioactivity standards of the department of health services in ch. DHS 157, Wis. Adm. Code, and to the National Interim Primary Drinking Water Regulations, 40 CFR part 141. These sections are adopted pursuant to s. 254.34, Stats.

NR 809.52(6)(6) Sample collection methods. Sample collection for radionuclide contaminants under s. NR 809.50 shall be conducted using the sample preservation, containers and maximum holding time procedures specified in Table Q. If a composite sample is prepared, a holding time cannot exceed 12 months. In all cases, samples should be analyzed as soon after collection as possible.

1 It is recommended that the preservative be added to the sample at the time of collection unless suspended solids activity is to be measured. If the sample has to be shipped to a laboratory or storage area unpreserved, acidification of the sample (in its original container) may be delayed for a period not to exceed 5 days. A minimum of 16 hours shall elapse between acidification and analysis.

NR 809.52 HistoryHistory: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 15-049: am. (1) Table N Register March 2016 No. 723, eff. 4-1-16.

NR 809.53(1)(a)(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).

NR 809.53(1)(b)1.1. 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.

NR 809.53(1)(b)2.2. 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.

NR 809.53(1)(c)(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:

NR 809.53(1)(c)1.1. Except as provided in subd. 2., water suppliers shall collect 4 consecutive quarterly samples at all sampling points before December 31, 2007.

NR 809.53(1)(c)2.2. 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:

NR 809.53(1)(c)2.a.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.

NR 809.53(1)(c)2.b.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.

NR 809.53(1)(c)2.c.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.

NR 809.53(1)(c)3.3. 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.

NR 809.53(1)(c)4.4. 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.

NR 809.53(1)(d)(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:

NR 809.53(1)(d)1.1. 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.

NR 809.53(1)(d)2.2. 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.