Section 809.333. Sampling locations for surface water source water monitoring.

 

(1)   General requirements. Water suppliers for public water systems required to conduct source water monitoring under s. NR 809.331 shall collect samples for each plant that treats a surface water or GWUDI source. Where multiple plants draw water from the same influent, such as the same pipe or intake, the department may approve one set of monitoring results to be used to satisfy the requirements of s. NR 809.331 for all plants.

(2)   Sample collection location. The water supplier shall collect source water samples prior to chemical treatment, such as coagulants, oxidants and disinfectants, unless the public water system meets the condition of this subsection. The department may approve a water supplier to collect a source water sample after chemical treatment if the department determines that collecting a sample prior to chemical treatment is not feasible for the public water system and that the chemical treatment is unlikely to have a significant adverse effect on the analysis of the sample.

(3)   Recycled filter backwash. Water suppliers for public water systems that recycle filter backwash water shall collect source water samples prior to the point of filter backwash water. All public water systems that recycle filter backwash water shall comply with all of the requirements under ss. NR 810.295 , 811.860 , and 811.862 .

(4)   Bank filtration.

(a) Water suppliers for public water systems that receive Cryptosporidium treatment credit for bank filtration under s. NR 810.29 (5) or 810.37 (2) , as applicable, shall collect source water samples in the surface water prior to bank filtration.

(b) Water suppliers for public water systems that use bank filtration as pretreatment to a filtration plant shall collect source water samples from the collector well after bank filtration. Use of bank filtration during monitoring shall be consistent with routine operational practice. When samples are collected after a bank filtration process, public water systems may not receive treatment credit for the bank filtration under s. NR 810.43 (3) .

(5)   Multiple sources. Water suppliers for public water systems with plants that use multiple water sources, including multiple surface water sources and blended surface water and groundwater sources, shall collect samples as specified in par. (a) or (b) . The use of multiple sources during monitoring shall be consistent with routine operational practice.

(a) If a sampling tap where the sources are combined prior to treatment is available, the water supplier shall collect samples from that tap.

(b) If a sampling tap where the sources are combined prior to treatment is not available, the water supplier shall collect samples at each source near the intake on the same day and shall follow either subd. 1. or 2. for sample analysis.

1. Water suppliers may composite samples from each source into one sample prior to analysis. The volume of sample from each source shall be weighted according to the proportion of the source in the total plant flow at the time the sample is collected.

2. Water suppliers may analyze samples from each source separately and calculate a weighted average of the analysis results for each sampling date. The weighted average shall be calculated by multiplying the analysis result for each source by the fraction the source contributed to total plant flow at the time the sample was collected and then summing these values.

(6)   Additional requirements. Water suppliers shall submit a description of their sampling locations to the department at the same time as the sampling schedule required under s. NR 809.332 . This description shall address the position of the sampling location in relation to the public water system's water sources and treatment processes, including pretreatment, points of chemical treatment, and filter backwash recycle. If the department does not respond to a water supplier regarding sampling locations, the water supplier shall sample at the reported locations.

CR 09-073 : cr. Register November 2010 No. 659 , eff. 12-1-10; correction in (3) made under s. 13.92 (4) (b) 7. , Stats., Register November 2010 No. 659 .