Section 327IAC8-2.6-18. Treatment performance toolbox options; requirements for microbial toolbox components; enhanced treatment for Cryptosporidium

   (a) A PWS using conventional filtration treatment or direct filtration treatment may receive an additional 0.5-log Cryptosporidium treatment credit during any month the system meets the following:

(1) Combined filter effluent (CFE) turbidity must be less than or equal to fifteen-hundredths (0.15) NTU in at least ninety-five percent (95%) of the measurements recorded each month.

(2) Turbidity must be measured as described in 327 IAC 8-2-8.7(4).

  (b) A PWS using conventional filtration treatment or direct filtration treatment may receive a 0.5-log Cryptosporidium treatment credit, which may be in addition to the 0.5-log credit under subsection (a), during any month the PWS meets the following criteria that must be based on monitoring as described in section 4 of this rule, as applicable:

(1) The filtered water turbidity for each individual filter must be less than or equal to fifteen-hundredths (0.15) NTU in at least ninety-five percent (95%) of the measurements recorded each month.

(2) No individual filter may have a measured turbidity greater than three-tenths (0.3) NTU in two (2) consecutive measurements taken fifteen (15) minutes apart.

(3) A PWS that has received credit for individual filter performance and fails to meet the requirements of subdivision (1) or (2) during any month will not receive a treatment technique violation under section 12(c) of this rule if the commissioner determines that the following conditions exist:

(A) The failure was due to unusual and short-term circumstances that could not reasonably be prevented through optimizing treatment plant:

(i) design;

(ii) operation; or

(iii) maintenance.

(B) The PWS has experienced not more than two (2) failures under this subsection in any calendar year.

  (c) Cryptosporidium treatment credit for drinking water treatment processes may be awarded to a PWS according to the following:

(1) Credits may be approved by the commissioner based on a demonstration of performance study or continuing operation that meets the following criteria:

(A) A PWS may not receive the prescribed credit for any toolbox option in section 17 of this rule, this section, and sections 19 and 20 of this rule if that toolbox option is included in a demonstration of performance study for which treatment credit is awarded under this subsection.

(B) The demonstration of performance study must:

(i) follow a protocol approved by the commissioner; and

(ii) demonstrate the level of Cryptosporidium reduction the treatment process will achieve under the full range of expected operating conditions for the PWS.

(C) Approval by the commissioner of the demonstration of performance study:

(i) must be in writing; and

(ii) may include monitoring and treatment performance criteria that:

(AA) shall be demonstrated and reported by the PWS to the commissioner on an ongoing basis in order to remain eligible for the treatment credit; and

(BB) the commissioner may designate, where necessary, to verify that routine operation continues to reflect the conditions under which the demonstration of performance credit was approved.

(2) The treatment credits may be:

(A) greater than or less than the prescribed treatment credits in section 12 or 17 of this rule, this section, and sections 19 and 20 of this rule; and

(B) awarded to treatment processes that do not meet the criteria for the prescribed credits.

(Water Pollution Control Division; 327 IAC 8-2.6-18; filed May 7, 2010, 9:30 a.m.: 20100602-IR-327080198FRA)