Current through September 18, 2024
Authority: IC 13-13-5; IC 13-14-8; IC 13-14-9; IC 13-18-3; IC
13-18-16
Affected: IC 13-18-3-11
Sec. 18.
(a) A PWS
using conventional filtration treatment or direct filtration treatment shall
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.
