Indiana Administrative Code
Title 327 - WATER POLLUTION CONTROL DIVISION
Article 8 - PUBLIC WATER SUPPLY
Rule 2.5 - Disinfectants and Disinfection
Section 2.5-17 - Operational evaluation levels; stage 2 disinfection byproducts requirements
Universal Citation: 327 IN Admin Code 2.5-17
Current through December 25, 2024
Authority: IC 13-13-5; IC 13-14-8-7; IC 13-14-9; IC 13-18-3-2; IC 13-18-16
Affected: IC 13-18-3-11
Sec. 17.
(a) A PWS has exceeded the operational evaluation level at any monitoring location when one (1) or both of the following occur:
(1)
The sum of the two (2) previous quarters' TTHM results plus twice the current
quarter's TTHM result, divided by four (4) to determine an average, exceeds
eighty-thousandths (0.080) milligrams per liter (mg/L).
(2) The sum of the two (2) previous quarters'
HAA5 results plus twice the current quarter's HAA5 result, divided by four (4)
to determine an average, exceeds sixty-thousandths (0.060) mg/L.
(b) The following are the requirements for a PWS if the operational evaluation level is exceeded:
(1) The PWS shall:
(A) conduct an operational evaluation;
and
(B) submit a written report of
the operational evaluation to the commissioner not later than ninety (90) days
after being notified of the analytical result that caused the PWS to exceed the
operational evaluation level.
The written report must be made available to the public upon request.
(2) The
operational evaluation must include the following:
(A) Treatment and distribution operational
practices, including:
(i) storage tank
operations;
(ii) excess storage
capacity;
(iii) distribution system
flushing;
(iv) changes in sources
or source water quality; and
(v)
treatment changes or problems; that can contribute to TTHM and HAA5
formation.
(B) Possible
steps that could be considered to minimize future exceedances.
(3) A PWS may request and the
commissioner may allow a PWS to limit the scope of the operational evaluation
required under subdivision (2) if the PWS is able to identify the cause of the
operational evaluation level exceedance.
(4) If the commissioner approves a PWS's
request under subdivision (3) to limit the scope of the operational evaluation,
the following apply:
(A) The commissioner
shall approve a request for a limited scope of operational evaluation in
writing.
(B) The PWS shall include
the commissioner's approval with the completed report on the limited scope
operational evaluation.
(C) The
commissioner's approval of a limited scope operational evaluation does not
extend the schedule under subdivision (1)(B) for submitting the written
report.
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