Section R. 325.10611k - Enhanced treatment for Cryptosporidium; microbial toolbox; treatment performance toolbox componentsRule 611k.
(1) Combined filter performance is a treatment performance toolbox component. Subpart H supplies that are subject to R 325.10611d and that use conventional filtration treatment or direct filtration treatment receive an additional 0.5-log Cryptosporidium treatment credit during any month the subpart H supply meets the criteria in this subrule. Combined filter effluent (CFE) turbidity shall be less than or equal to 0.15 NTU in not less than 95% of the measurements. Turbidity shall be measured as described in R 325.10605 and R 325.10720 (2).(2) Individual filter performance is a treatment performance toolbox component. Compliance with the criteria in this subrule shall be based on individual filter turbidity monitoring as described in R 325.10720 (2) (c) to (d). Subpart H supplies using conventional filtration treatment or direct filtration treatment receive 0.5-log Cryptosporidium treatment credit, which can be in addition to the 0.5-log credit under subrule (1) of this rule, during any month the supply meets all of the following criteria:(a) The filtered water turbidity for each individual filter shall be less than or equal to 0.15 NTU in not less than 95% of the measurements recorded each month.(b) No individual filter may have a measured turbidity greater than 0.3 NTU in 2 consecutive measurements taken 15 minutes apart.(c) A supply that has received treatment credit for individual filter performance and fails to meet the requirements of subdivision (a) or (b) of this subrule during any month does not receive a treatment technique violation under R 325.10611f (3) if the department determines both of the following: (i) The failure was due to unusual and short-term circumstances that could not reasonably be prevented through optimizing treatment plant design, operation, and maintenance.(ii) The supply has experienced not more than 2 such failures in any calendar year.(3) Demonstration of performance is a treatment performance toolbox component. The department may approve Cryptosporidium treatment credit for drinking water treatment processes based on a demonstration of performance study. This treatment credit may be greater than or less than the prescribed treatment credits in R 325.10611f or R 325.10611j to R 325.10611m and may be awarded to treatment processes that do not meet the criteria for the prescribed credits. All of the following apply to the demonstration of performance study:(a) Subpart H supplies cannot receive the prescribed treatment credit for any toolbox option in R 325.10611j to R 325.10611m if that toolbox option is included in a demonstration of performance study for which treatment credit is awarded under this subrule.(b) The demonstration of performance study shall follow a department-approved protocol, using pilot plant studies or other means, and shall demonstrate the level of Cryptosporidium reduction the treatment process will achieve under the full range of expected operating conditions for the supply.(c) Approval by the department shall be in writing and may include monitoring and treatment performance criteria that the supply shall demonstrate and report on an ongoing basis to remain eligible for the treatment credit. The department may designate those criteria where necessary to verify that the conditions under which the demonstration of performance credit was approved are maintained during routine operation.Mich. Admin. Code R. 325.10611k