Section 327IAC8-2.6-15. Microbial toolbox options for meeting Cryptosporidium treatment requirements; requirements for microbial toolbox components; enhanced treatment for Cryptosporidium

   (a) A PWS may:

(1) receive the treatment credits listed under Table 15 in subsection (b) by meeting the conditions for microbial toolbox options described in sections 16 through 20 of this rule; and

(2) apply the treatment credits received under subdivision (1) to meet the treatment requirements in section 12 of this rule.

  (b) The following table summarizes options in the microbial toolbox:

Table 15

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
Watershed Control Plan	0.5-log credit for commissioner-approved program comprising required elements, annual program status, report to commissioner, and regular watershed survey. Specific criteria are under section 16(a) of this rule.
Alternative source/intake management	No prescribed credit. Systems may conduct simultaneous monitoring for treatment bin classification at alternative intake locations or under alternative intake management strategies. Specific criteria are under section 16(b) of this rule.
Prefiltration Toolbox Options
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 commissioner-approved performance criteria. To be eligible, basins must be operated continuously with coagulant addition and all plant flow must pass through the basins. Specific criteria are under section 17(a) of this rule.
Two-stage lime softening	0.5-log credit for two-stage lime softening where chemical addition and hardness precipitation occur in both stages. All plant flow must pass through both stages. Single-stage softening is credited as equivalent to conventional treatment. Specific criteria are under section 17(b) of this rule.
Bank filtration	0.5-log credit for 25-foot setback; 1-log credit for 50-foot setback; aquifer must be unconsolidated sand containing at least 10% fines; average turbidity in wells must be less than one NTU. Systems using wells followed by filtration, when conducting source water monitoring must sample the well to determine bin classification and are not eligible for additional credit. Specific criteria are under section 17(b) of this rule.
Treatment performance toolbox options
Combined filter performance	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 section 18(a) of this rule.
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 at least 95%) of samples each month in each filter and never greater than 0.3 NTU in two consecutive measurements in any filter. Specific criteria are under section 18(b) of this rule.
Demonstration of performance	Credit awarded to unit processes or treatment train based on a demonstration to the commissioner with a commissioner-approved protocol. Specific criteria are under section 18(c) of this rule.
Additional filtration toolbox options
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 under section 19(a) of this rule.
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 under section 19(a) of this rule.
Membrane filtration	Log credit equivalent to removal efficiency demonstrated in challenge test for device if supported by direct integrity testing. Specific criteria are under section 19(b) of this rule.
Second stage filtration	0.5-log credit for second separate granular media filtration stage if treatment train includes coagulation prior to first filter. Specific criteria are under section 19(c) of this rule.
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 under section 19(d) of this rule.
Inactivation toolbox options
Chlorine dioxide	Log credit based on measured CT in relation to CT table. Specific criteria are under section 20(b) of this rule.
Ozone	Log credit based on measured CT in relation to CT table. Specific criteria are under section 20(b) of this rule.
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 under section 20(d) of this rule.

(Water Pollution Control Division; 327 IAC 8-2.6-15; filed May 7, 2010, 9:30 a.m.: 20100602-IR-327080198FRA)