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 III - Toolbox Options for Meeting Enhanced Treatment for Cryptosporidium Requirements
Section NR 810.41 - Microbial toolbox options
Universal Citation: WI Admin Code ยง NR 810.41
Current through August 26, 2024
(1)
(a) Public water systems receive the
treatment credits listed in the table in sub. (2) by meeting the conditions for
microbial toolbox options described in ss.
NR 810.42 to 810.46. Systems apply these treatment
credits to meet the treatment requirements in s.
NR 810.35 or 810.36, as applicable.
(b) Unfiltered GWUDI systems are eligible for
treatment credits for the microbial toolbox options described in s.
NR 810.46 only.
(2) The following table summarizes options in the microbial toolbox:
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 | |
| (1) Watershed control program | 0.5-log credit for department-approved program comprising required elements, annual program status report to department, and regular watershed survey. Unfiltered systems are not eligible for credit. Specific criteria are in s. NR 810.42(1). |
| (2) Alternative source/ intake management | No prescribed credit. Systems may conduct simultaneous monitoring for treatment bin classifica-tion at alternative intake locations or under alternative intake management strategies. Specific criteria are in s. NR 810.42(2). |
| Pre Filtration Toolbox Options | |
| (3) Presedimentation basin with coagulation | 0.5-log credit during any 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 s. NR 810.43(1). |
| (4) 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 s. NR 810.43(2). |
| (5) Bank filtration | 0.5-log credit for 25-foot setback; 1.0-log credit for 50-foot setback; aquifer shall be unconsoli-dated sand containing at least 10% fines; average turbidity in wells shall be less than one NTU. Systems using wells followed by filtration when conducting source water monitoring shall sam-ple the well to determine bin classification and are not eligible for additional credit. Specific criteria are in s. NR 810.43(3). |
| Treatment Performance Toolbox Options | |
| (6) Combined filter per-formance | 0.5-log credit for combined filter effluent turbidity less than or equal to 0.15 NTU in at least 95% of measurements each month. Specific criteria are in s. NR 810.44(1). |
| (7) Individual filter per-formance | 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 at least 95% of samples each month in each filter and is never greater than 0.3 NTU in 2 consecutive measurements in any filter. Spe-cific criteria are in s. NR 810.44(2). |
| (8) 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 s. NR 810.44(3). |
| Additional Filtration Toolbox Options | |
| (9) Bag or cartridge fil-ters (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 s. NR 810.45(1). |
| (10) 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 s. NR 810.45(1). |
| (11) Membrane filtra-tion | Log credit equivalent to removal efficiency demonstrated in challenge test for device if sup-ported by direct integrity testing. Specific criteria are in s. NR 810.45(2). |
| (12) Second stage filtration | 0.5-log credit for second separate granular media filtration stage if treatment train includes coag-ulation prior to first filter. Specific criteria are in s. NR 810.45(3) |
| Toolbox Option | Cryptosporidium treatment credit with design and implementation criteria |
| Additional Filtration Toolbox Options | |
| (13) 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 s. NR 810.45(4). |
| Inactivation Toolbox Options | |
| (14) Chlorine dioxide | Log credit based on measured CT in relation to CT table. Specific criteria are in s. NR 810.46(2) |
| (15) Ozone | Log credit based on measured CT in relation to CT table. Specific criteria are in s. NR 810.46(2). |
| (16) 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 are in s. NR 810.46(4). |
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