R 325.10611h Enhanced treatment for Cryptosporidium; microbial toolbox options for meeting Cryptosporidium treatment requirements.

Rule 611h. (1) Subpart H supplies that are subject to R 325.10611d receive the treatment credits listed in the table in subrule (2) of this rule by meeting the conditions for microbial toolbox options described in R 325.10611i to R 325.10611m. Subpart H supplies apply these treatment credits to meet the treatment requirements in R 325.10611f. (2) The following table summarizes options in the microbial toolbox: Table 1 Microbial Toolbox Summary Table: Options, Treatment Credits, and Criteria Toolbox Option Cryptosporidium treatment credit with design and implementation criteria Source Protection and Management Toolbox Options (a) Watershed control program 0.5-log credit for department-approved program comprising required elements, annual program status report to department, and regular watershed survey. Specific criteria are in R 325.10611i (1). (b) Alternative source/intake management No prescribed credit. Subpart H supplies may conduct simultaneous monitoring for treatment bin classification at alternative intake locations or under alternative intake management strategies. Specific criteria are in R 325.10611i (2). Pre Filtration Toolbox Options (c) Presedimentation basin with coagulation 0.5-log credit during a month that presedimentation basins achieve a monthly mean reduction of 0.5-log or greater in turbidity or alternative department-approved performance criteria. To be eligible, basins shall be operated continuously with coagulant addition and all plant flow shall pass through basins. Specific criteria are in R 325.10611j (1). (d) Two-stage lime softening 0.5-log credit for 2-stage softening where chemical addition and hardness precipitation occur in both stages. All plant flow shall pass through both stages. Single-stage softening is credited as equivalent to conventional treatment. Specific criteria are in R 325.10611j (2). (e) Bank filtration 0.5-log credit for 25-foot setback; 1.0- log credit for 50-foot setback; aquifer shall be unconsolidated sand containing not less than 10% fines; average turbidity in wells shall be less than 1 NTU. Subpart H supplies using wells followed by filtration when conducting source water monitoring shall sample the well to determine bin classification and are not eligible for additional credit. Specific criteria are in R 325.10611j (3). Treatment Performance Toolbox Options (f) Combined filter performance 0.5-log credit for combined filter effluent turbidity less than or equal to 0.15 NTU in not less than 95% of measurements each month. Specific criteria are in R 325.10611k (1). (g) Individual filter performance 0.5-log credit (in addition to 0.5-log combined filter performance credit) if individual filter effluent turbidity is less than or equal to 0.15 NTU in not less than 95% of samples each month in each filter and is never greater than 0.3 NTU in 2 consecutive measurements in a filter. Specific criteria are in R 325.10611k (2). (h) Demonstration of performance Credit awarded to unit process or treatment train based on a demonstration to the department with a department-approved protocol. Specific criteria are in R 325.10611k (3). Additional Filtration Toolbox Options (i) Bag or cartridge filters (individual filters). Up to 2-log credit based on the removal efficiency demonstrated during challenge testing with a 1.0-log factor of safety. Specific criteria are in R 325.10611l (1). (j) Bag or cartridge filters (in series). Up to 2.5-log credit based on the removal efficiency demonstrated during challenge testing with a 0.5-log factor of safety. Specific criteria are in R 325.10611l (1). (k) Membrane filtration Log credit equivalent to removal efficiency demonstrated in challenge test for device if supported by direct integrity testing. Specific criteria are in R 325.10611l (2). (l) Second stage filtration 0.5-log credit for second separate granular media filtration stage if treatment train includes coagulation before first filter. Specific criteria are in R 325.10611l (3). (m) Slow sand filters 2.5-log credit as a secondary filtration step; 3.0-log credit as a primary filtration process. No prior chlorination for either option. Specific criteria are in R 325.10611l (4). Inactivation Toolbox Options (n) Chlorine dioxide Log credit based on measured CT in relation to CT table. Specific criteria in R 325.10611m (2). (o) Ozone Log credit based on measured CT in relation to CT table. Specific criteria in R 325.10611m (2). (p) UV Log credit based on validated UV dose in relation to UV dose table; reactor validation testing required to establish UV dose and associated operating conditions. Specific criteria in R 325.10611m (4).