Section 327IAC8-2.5-16. Conditions requiring increased monitoring; stage 2 disinfection byproducts requirements

   (a) A PWS that is required to monitor at a particular location annually or less frequently than annually under section 12 or 14 of this rule shall increase monitoring to dual sample sets once per quarter (taken every ninety (90) days) at all locations if one (1) or both of the following occur:

(1) TTHM sample is greater than eighty-thousandths (0.080) milligrams per liter (mg/L).

(2) HAA5 sample is greater than sixty-thousandths (0.060) mg/L at any location.

  (b) A PWS is in violation of the following:

(1) MCL when the LRAA:

(A) exceeds the MCLs contained in section 2(b) of this rule, calculated based on four (4) consecutive quarters of monitoring; or

(B) is calculated based on fewer than four (4) quarters of data and the MCL would be exceeded regardless of the monitoring results of subsequent quarters.

(2) Monitoring requirements for each quarter that a monitoring result would be used in calculating an LRAA if the PWS fails to monitor.

  (c) A PWS may return to routine monitoring once it has conducted increased monitoring for at least four (4) consecutive quarters and the LRAA for every monitoring location meets the following:

(1) Less than or equal to sixty-thousandths (0.060) mg/L for TTHM.

(2) Less than or equal to forty-five thousandths (0.045) mg/L for HAA5.

(Water Pollution Control Division; 327 IAC 8-2.5-16; filed May 7, 2010, 9:30 a.m.: 20100602-IR-327080198FRA; errata filed Nov 8, 2012, 8:37 a.m.: 20121121-IR-327120591ACA)