Section 327IAC8-2.5-2. Maximum contaminant levels; disinfection byproducts

   (a) The MCLs for disinfection byproducts are as follows:

Disinfection Byproduct	MCL (mg/L)
TTHM	0.080
HAA5	0.060
Bromate	0.010
Chlorite	1.0

(1) Subpart H systems shall comply with this subsection according to the following:

(A) Beginning January 1, 2002, for a system serving ten thousand (10,000) or more persons.

(B) Beginning January 1, 2004, for systems serving fewer than ten thousand (10,000) persons and systems using only ground water not under the direct influence of surface water.

(2) The commissioner hereby identifies the following as the best technology, treatment techniques, or other means available for achieving compliance with the MCLs for disinfection byproducts identified in this subsection:

Disinfection Byproduct	Best Available Technology
TTHM	Enhanced coagulation or enhanced softening or GAC10, with chlorine as the primary and residual disinfectant.
HAA5	Enhanced coagulation or enhanced softening or GAC10, with chlorine as the primary and residual disinfectant.
Bromate	Control of ozone treatment process to reduce production of bromate.
Chlorite	Control of treatment processes to reduce disinfectant demand and control of disinfection treatment processes to reduce disinfectant levels.

  (b) This subsection relates to LRAA compliance under sections 11 through 20 of this rule. The MCLs for TTHM and HAA5 are as follows:

Disinfection Byproduct	MCL (mg/L)
TTHM	0.080
HAA5	0.060

(1) The MCLs for TTHM and HAA5 must be complied with as a LRAA at each monitoring location beginning at the date specified for compliance in section 11(c) of this rule.

(2) The commissioner hereby identifies the following as the best technology, treatment techniques, or other means available for achieving compliance with the MCLs for TTHM and HAA5 identified in this subsection for all systems that disinfect their source water:

Disinfection Byproduct	Best Available Technology
TTHM and HAA5	Enhanced coagulation or enhanced softening plus GAC10, or nanofiltration with a molecular weight cutoff less than or equal to one thousand (1,000) Daltons, or GAC20.

(3) The commissioner hereby identifies the following as the BAT, treatment techniques, or other means available for achieving compliance with the MCLs for TTHM and HAA5 identified in this subsection for consecutive systems and applies only to the disinfected water that consecutive systems buy or otherwise receive:

Disinfection Byproduct	Best Available Technology
TTHM and HAA5	Systems serving greater than or equal to ten thousand (10,000): Improved distribution system and storage tank management to reduce residence time, plus the use of chloramines for disinfectant residual maintenance. Systems serving less than ten thousand (10,000): Improved distribution system and storage tank maintenance to reduce residence time.

(Water Pollution Control Division; 327 IAC 8-2.5-2; filed May 1, 2003, 12:00 p.m.: 26 IR 2840; filed May 7, 2010, 9:30 a.m.: 20100602-IR-327080198FRA)