Section R. 325.10611e - Enhanced treatment for Cryptosporidium; treatment technique; bin classificationRule 611e.
(1) Following completion of the initial round of source water monitoring required under 40 CFR §141.701 (a), as adopted by reference in R 325.10720b, subpart H supplies that are subject to R 325.10611d shall calculate an initial Cryptosporidium bin concentration for each plant for which monitoring was required. These public water supplies are also considered "water supplies" or "supplies" in this rule. Calculation of the bin concentration shall use the Cryptosporidium results reported under 40 CFR §141.701 (a) and shall follow the procedures in subrule (2) of this rule.(2) Supplies shall use the following criteria to determine bin classification:(a) For supplies that collect a total of not less than 48 samples, the bin concentration is equal to the arithmetic mean of all sample concentrations.(b) For supplies that collect a total of not less than 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 supplies that serve fewer than 10,000 people and monitor for Cryptosporidium for only 1 year, that is, collect 24 samples in 12 months, the bin concentration is equal to the arithmetic mean of all sample concentrations.(d) For supplies with plants operating only part of the year that monitor fewer than 12 months per year under 40 CFR §141.701 (e), as adopted by reference in R 325.10720b, the bin concentration is equal to the highest arithmetic mean of all sample concentrations during a year of Cryptosporidium monitoring.(e) If the monthly Cryptosporidium sampling frequency varies, supplies shall first calculate a monthly average for each month of monitoring. Supplies shall then use these monthly average concentrations, rather than individual sample concentrations, in the applicable calculation for bin classification in subdivisions (a) to (d) of this subrule.(3) Supplies shall determine their initial bin classification from the following table and using the Cryptosporidium bin concentration calculated under subrules (1) and (2) of this rule: Bin Classification Table for Filtered Supplies
| For supplies that are: | With a Cryptosporidium bin concentration of ...* | The bin classification is.... |
| ... required to monitor for Cryptosporidium under 40 CFR 141.701 as adopted by reference in R 325.10720b. | Cryptosporidium less than 0.075 oocyst/L | Bin 1. |
| Cryptosporidium greater than or equal to 0.075 and less than 1.0 oocysts/L | Bin 2 |
| Cryptosporidium greater than or equal to 1.0 and less than 3.0 oocysts/L | Bin 3 |
| Cryptosporidium greater than or equal to 3.0 oocysts/L. | Bin 4 |
| ... serving fewer than 10,000 people and NOT required to monitor for Cryptosporidium under 40 CFR 141.701 (a) (4). | Not applicable | Bin 1 |
* Based on calculations in subrule (1) or (4) of this rule, as applicable.
(4) Following completion of the second round of source water monitoring required under 40 CFR §141.701 (b), supplies shall recalculate their Cryptosporidium bin concentration using the Cryptosporidium results reported under 40 CFR §141.701 (b) and following the procedures in subrule (2) (a) to (d) of this rule. Supplies shall then redetermine their bin classification using this bin concentration and the table in subrule (3) of this rule.(5) The following apply to reporting the bin classification to the department: (a) Supplies shall report their initial bin classification under subrule (3) of this rule to the department for approval not later than 6 months after the supply is required to complete initial source water monitoring based on the schedule in 40 CFR 141.701 (c).(b) Supplies shall report their bin classification under subrule (4) of this rule to the department for approval not later than 6 months after the supply is required to complete the second round of source water monitoring based on the schedule in 40 CFR 141.701 (c).(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 subrule (5) of this rule is a violation of the treatment technique requirement.Mich. Admin. Code R. 325.10611e