Wisconsin Administrative Code
Department of Natural Resources
NR 800 - Environmental Protection - Water Supply
Chapter NR 810 - Requirements for the operation and maintenance of public water systems
Subchapter II - Surface Water Treatment and Groundwater Under the Direct Influence of Surface Water Treatment Operations
Section NR 810.34 - Cryptosporidium bin classification for filtered systems

Universal Citation: WI Admin Code ยง NR 810.34

Current through August 26, 2024

(1) Following completion of the initial round of source water monitoring required under s. NR 809.331(1), water suppliers for filtered systems shall calculate an initial Cryptosporidium bin concentration for each plant for which monitoring was required. Calculation of the bin concentration shall use the Cryptosporidium results reported under s. NR 809.331(1) and shall follow the procedures in sub. (2) (a) to (e).

(2)

(a) For filtered systems that collect a total of at least 48 samples, the bin concentration is equal to the arithmetic mean of all sample concentrations.

(b) For filtered systems that collect a total of at least 24 samples, but not more than 47 samples, the bin concentration is equal to the highest arithmetic mean of all sample concentrations in any 12 consecutive months during which Cryptosporidium samples were collected.

(c) For filtered systems that serve fewer than 10,000 people and monitor for Cryptosporidium for only one year, collecting 24 samples in 12 months, the bin concentration is equal to the arithmetic mean of all sample concentrations.

(d) For filtered systems with plants operating only part of the year that monitor fewer than 12 months per year under s. NR 809.331(5), the bin concentration is equal to the highest arithmetic mean of all sample concentrations during any year of Cryptosporidium monitoring.

(e) If the monthly Cryptosporidium sampling frequency varies, water suppliers shall first calculate a monthly average for each month of monitoring. Systems shall then use these monthly average concentrations, rather than individual sample concentrations, in the applicable calculation for bin classification in pars. (a) to (d).

(3) Water suppliers for filtered systems shall determine their initial bin classification from the following table and using the Cryptosporidium bin concentration calculated under subs. (1) and (2):

Bin Classification Table for Filtered Systems

For systems that are: With a Cryptosporidium bin concentration ot: 1 The bin classification is:
Required to monitor for Cryptospo-ridium under s. NR 809.331 Cryptosporidium[LESS than]0.075 oocyst/L Bin 1
0.075 oocysts/L [LESS than]= Cryptosporidium [LESS than] 1.0 oocysts/L Bin 2
1.0 oocysts/L [LESS than]= Cryptosporidium [LESS than] 3.0 oocysts/L Bin 3
Cryptosporidium [GREATER than]= 3.0 oocysts/L Bin 4
Serving fewer than 10,000 people and NOT required to monitor for Cryptosporidium under s. NR 809.331(1) (d) NA Bin 1

1 Based on calculations in sub. (1) or (4), as applicable.

(4) Following completion of the second round of source water monitoring required under s. NR 809.331(2), water suppliers for filtered systems shall recalculate their Cryptosporidium bin concentration using the Cryptosporidium results reported under s. NR 809.331(2) and following the procedures in sub. (2) (a) to (d). Systems shall then redetermine their bin classification using this bin concentration and the table in sub. (3).

(5) Water suppliers shall report their bin classification of the water system as follows:

(a) Water suppliers for filtered systems shall report the initial bin classification under par. (c) to the department for approval no later than 6 months after the system is required to complete initial source water monitoring based on the schedule in s. NR 809.331(3).

(b) Water suppliers for filtered systems shall report the bin classification under sub. (4) to the department for approval no later than 6 months after the system is required to complete the second round of source water monitoring based on the schedule in s. NR 809.331(3).

(c) The bin classification report to the department shall include a summary of source water monitoring data and the calculation procedure used to determine bin classification.

(6) Failure to comply with the conditions of sub. (5) is a violation of the treatment technique requirement.

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