NR 809.245(4)(b) (b) If previous use of the contaminant is unknown or it has been used previously, then the following factors shall be used to determine whether a waiver is granted.

NR 809.245(4)(b)1. 1. Previous analytical results.

NR 809.245(4)(b)2. 2. The proximity of the public water system to potential point or non-point source of contamination. Point sources include spills and leaks of chemicals at or near a water treatment facility or at manufacturing, distribution or storage facilities, or from hazardous and municipal waste landfills and other waste handling or treatment facilities.

NR 809.245(4)(b)3. 3. The environmental persistence and transport of the contaminants.

NR 809.245(4)(b)4. 4. The number of persons served by the public water system and the proximity of a smaller public water system to a larger public water system.

NR 809.245(4)(b)5. 5. How well the water source is protected against contamination. Groundwater systems shall consider factors such as depth of the well, the type of soil and wellhead protection.

NR 809.245(5) (5) Waiver conditions and monitoring assessments. A water supplier for a groundwater system shall take one sample at each entry point during the time the waiver is effective. As a condition of the waiver under sub. (4), water supplier for the groundwater system shall update the monitoring assessment considering the factors listed in sub. (4). Based on this monitoring assessment, the department shall reconfirm that the public water system is non-vulnerable. If the department does not make this reconfirmation within 3 years of the initial determination or each subsequent determination, then the waiver is invalidated and the public water system is required to sample during each compliance period as specified in sub. (2) (b).

NR 809.245(6) (6) monitoring for detected compounds. If vinyl chloride is detected at a level exceeding 0.0002 mg/L, or any other VOC contaminant specified in s. NR 809.24 is detected at a level exceeding 0.0005 mg/1 in any sample, then:

NR 809.245(6)(a) (a) The public water system shall be monitored quarterly for all VOCs under s. NR 809.24 at each sampling location which resulted in a detection.

NR 809.245(6)(b) (b) The department may decrease the quarterly monitoring requirement specified in par. (a) if the department has determined that the public water system is reliably and consistently below the MCL. In no case may the department make this determination unless a groundwater system has been sampled a minimum of 2 quarters and a surface water system has been sampled a minimum of 4 quarters.

NR 809.245(6)(c) (c) If the department determines that the public water system is reliably and consistently below the MCL, the department may allow the system to be monitored annually. Public water systems which are monitored annually shall be monitored during the quarter which previously yielded the highest analytical result.

NR 809.245(6)(d) (d) Water suppliers for public water systems which have 3 consecutive annual samples with no detection of a contaminant may apply to the department for a waiver as specified in sub. (3).

NR 809.245(7) (7) Monitoring when an MCL is exceeded. Additional monitoring for volatile organic contaminants shall be required as follows in order to maintain compliance.

NR 809.245(7)(a) (a) If a VOC contaminant specified in s. NR 809.24 is detected at a level exceeding the MCL in any sample, then the water supplier shall begin to take quarterly samples at each entry point which exceeded a MCL.

NR 809.245(7)(b) (b) Water suppliers for public water systems which exceed a MCL listed in s. NR 809.24 shall be monitored quarterly. After a minimum of 4 quarterly samples that show the public water system is back in compliance and the department determines the public water system is reliably and consistently below the MCL as specified in s. NR 809.247 (1), the water supplier for the public water system shall be monitored at the frequency specified in sub. (6) (c).

NR 809.245(8) (8) Confirmation samples. The department may require a confirmation sample for positive or negative results. The department may delete results of sampling errors from any compliance calculation, or may require the collection of additional samples to determine whether the result is or is not in error. When a confirmation sample is required, the result shall be averaged with the first sampling result and the average used for the compliance determination as specified in s. NR 809.247 (1) (c)

NR 809.245(9) (9) Composite samples. The department may reduce the total number of samples a water supplier for a public water system shall analyze by allowing the use of compositing. The following composite sampling requirements shall be met:

NR 809.245(9)(a) (a) Compositing may only be permitted for entry points within a single public water system. Composite samples from a maximum of 5 entry points may be allowed, if the detection limit of the method used for analysis is less than one-fifth of the MCL.

NR 809.245(9)(b) (b) Compositing of samples shall be done in the laboratory and analyzed within 14 days of sample collection according to the procedures in s. NR 809.243 (1) Table E.

NR 809.245(9)(c) (c) If the concentration in the composite sample is greater than 0.0002 mg/L for vinyl chloride or 0.0005mg/L for any other contaminant listed under s. NR 809.24, then a follow-up sample shall be taken and analyzed for each contaminant detected within 14 days from each entry point included in the composite.

NR 809.245(9)(d) (d) If duplicates of the original sample taken from each sampling point used in the composite are available, the water supplier may use these instead of re-sampling. The duplicate shall be analyzed and the results reported to the department within 14 days of collection.

NR 809.245(10) (10) Increasing monitoring frequency. The department may increase monitoring requirements if necessary to detect contaminant variations within a public water system.

NR 809.245(11) (11) Designation of sampling times. Each public water system shall be monitored during the month, quarter or year designated by the department within each compliance period.

NR 809.245 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 15-049: am. (2) (a) 1., (b), (5), (7) (b), (9) (c) Register March 2016 No. 723, eff. 4-1-16.

NR 809.247 NR 809.247 Compliance requirements for volatile organic contaminants.

NR 809.247(1) (1) MCL compliance determination. Compliance with volatile organic contaminant MCLs shall be determined as follows:

NR 809.247(1)(a) (a) Compliance with the VOC MCLs specified in s. NR 809.24 shall be determined based on the analytical results obtained at each entry point. If one entry point is in violation of an MCL, the public water system is in violation of the MCL.

NR 809.247(1)(b) (b) For public water systems which are monitored more frequently than annually, compliance is determined by a running annual average of all samples taken at each entry point. If the annual average of any entry point is greater than the MCL, the public water system is out of compliance. If the initial sample or a subsequent sample would cause the annual average to exceed the MCL, the public water system is out of compliance immediately.

NR 809.247(1)(c) (c) If monitoring is conducted annually, or less frequently, the public water system is out of compliance if the level of a contaminant at any entry point is greater than the MCL. Compliance shall be based on the concentration of this sample or the average value of this sample and the confirmation sample, if the department required a confirmation sample.