Section 327IAC8-2.5-9. Treatment techniques for control of disinfection byproducts precursors

   (a) Applicability is as follows:

(1) Subpart H systems using conventional filtration treatment shall operate with enhanced coagulation or enhanced softening to achieve the TOC percent removal levels specified in subsection (b) unless the system meets at least one (1) of the alternative compliance criteria listed in subdivision (2) or (3).

(2) Subpart H systems using conventional filtration treatment may use one (1) or more of the following alternative compliance criteria to comply with this section instead of complying with subsection (b):

(A) The system's source water TOC level, measured according to section 5(d)(3) of this rule, is less than two and zero-tenths (2.0) milligrams per liter, calculated quarterly as a running annual average.

(B) The system's treated water TOC level, measured according to section 5(d)(3) of this rule, is less than two and zero-tenths (2.0) milligrams per liter, calculated quarterly as a running annual average.

(C) The system's source water TOC level, measured according to section 5(d)(3) of this rule, is less than four and zero-tenths (4.0) milligrams per liter, calculated quarterly as a running annual average and the following are met:

(i) The source water alkalinity, measured according to section 5(d)(1) of this rule, is greater than sixty (60) milligrams per liter (as CaCO₃), calculated quarterly as a running annual average.

(ii) Either of the following:

(AA) The TTHM and HAA5 running annual averages are no greater than forty-thousandths (0.040) milligram per liter and thirty-thousandths (0.030) milligram per liter, respectively.

(BB) Before the effective date for compliance in section 4(b) of this rule, the system has made a clear and irrevocable financial commitment not later than the effective date for compliance in section 4(b) of this rule to use technologies that will limit the levels of TTHMs and HAA5 to not more than forty-thousandths (0.040) milligram per liter and thirty-thousandths (0.030) milligram per liter, respectively. Systems shall submit evidence of a clear and irrevocable financial commitment, in addition to a schedule containing milestones and periodic progress reports for installation and operation of appropriate technologies, to the commissioner for approval not later than the effective date for compliance in section 4(b) of this rule. These technologies must be installed and operating not later than June 30, 2005.

(D) The TTHM and HAA5 running annual averages are not greater than forty-thousandths (0.040) milligram per liter and thirty-thousandths (0.030) milligram per liter, respectively, and the system uses only chlorine for primary disinfection and maintenance of a residual in the distribution system.

(E) The system's source water SUVA, before any treatment and measured monthly according to section 5(d)(4) of this rule, is less than or equal to two and zero-tenths (2.0) liters per milligram meter, calculated quarterly as a running annual average.

(F) The system's finished water SUVA, measured monthly according to section 5(d)(4) of this rule, is less than or equal to two and zero-tenths (2.0) liters per milligram meter, calculated quarterly as a running annual average.

(3) Systems practicing enhanced softening that cannot achieve the TOC removals required by subsection (b)(2) may use the following alternative compliance criteria instead of complying with subsection (b):

(A) Softening that results in lowering the treated water alkalinity to less than sixty (60) milligrams per liter (as CaCO₃), measured monthly according to section 5(d)(1) of this rule and calculated quarterly as a running annual average.

(B) Softening that results in removing at least ten (10) milligrams per liter of magnesium hardness (as CaCO₃), measured monthly according to section 5(d)(5) of this rule and calculated quarterly as an annual running average.

Systems shall comply with monitoring requirements in section 6(d) of this rule.

  (b) Enhanced coagulation and enhanced softening performance requirements are as follows:

(1) Systems shall achieve the percent reduction of TOC specified in subdivision (2) between the source water and the combined filter effluent unless the commissioner approves a system's request for alternate minimum TOC removal (Step 2) requirements under subdivision (3).

(2) Required Step 1 TOC reductions, indicated in the following table, are based upon specified source water parameters measured in accordance with section 6(d) of this rule. Systems practicing softening are required to meet the Step 1 TOC reductions in the far right column (source water alkalinity greater than one hundred twenty (120) milligrams per liter) for the specified source water TOC:

Step 1 Required Removal of TOC by Enhanced Coagulation and Enhanced Softening

for Subpart H Systems Using Conventional Treatment^{1, 2}

	Source-Water Alkalinity, mg/L as CaCO3
Source-Water TOC, mg/L	0-60	>60-120	>1203
>2.0-4.0	35.0%	25.0%	15.0%
>4.0-8.0	45.0%	35.0%	25.0%
>8.0	50.0%	40.0%	30.0%

¹Systems meeting at least one (1) of the conditions in subsection (a)(2) are not required to operate with enhanced coagulation.

²Softening systems meeting one (1) of the alternative compliance criteria in subsection (a)(3) are not required to operate with enhanced softening.

³Systems practicing softening shall meet the TOC removal requirements in this column.

(3) Subpart H conventional treatment systems that cannot achieve the Step 1 TOC removals required by subdivision (2) due to water quality parameters or operational constraints shall comply with the following regarding alternate minimum TOC (Step 2) removal:

(A) The system shall apply to the commissioner, within three (3) months of failure to achieve the TOC removals required by subdivision (2), for approval of alternate minimum TOC (Step 2) removal requirements submitted by the system as provided by subdivision (4).

(B) If the commissioner approves the alternate minimum TOC removal (Step 2) requirements, the commissioner may make those requirements retroactive for the purposes of determining compliance. Until the commissioner approves the alternate minimum TOC removal (Step 2) requirements, the system shall meet the Step 1 TOC removals contained in subdivision (2).

(4) Alternate minimum TOC removal (Step 2) requirements are as follows:

(A) Applications made to the commissioner by enhanced coagulation systems for approval of alternate minimum TOC removal (Step 2) requirements under subdivision (3) must include, at a minimum, results of bench-scale or pilot-scale testing conducted under clause (C). The submitted bench-scale or pilot-scale testing will be used to determine the alternate enhanced coagulation level.

(B) As used in this subdivision, "alternate enhanced coagulation level" is described by the following sequential process:

(i) The term means coagulation at a coagulant dose and pH as determined by the method described in clause (A), this clause, and clauses (C) through (E) such that an incremental addition of ten (10) milligrams per liter of alum (or equivalent amount of ferric salt) results in a TOC removal of less than or equal to three-tenths (0.3) milligram per liter.

(ii) The percent removal of TOC calculated under item (i) on the TOC removal versus coagulant dose curve is defined as the minimum TOC removal required for the system.

(iii) Once approved by the commissioner, the minimum TOC removal requirement calculated under item (ii):

(AA) supersedes the minimum TOC removal required by the table in subdivision (2); and

(BB) will be effective until the commissioner approves a new value based on the results of a new bench-scale and pilot-scale tests.

Failure to achieve alternate minimum TOC removal levels is a violation of this subsection.

(C) Bench-scale or pilot-scale testing of enhanced coagulation must be conducted by using representative water samples and adding ten (10) milligrams per liter increments of alum, or equivalent amounts of ferric salt, until the pH is reduced to a level less than or equal to the enhanced coagulation Step 2 target pH shown in the following table:

Enhanced Coagulation Step 2 Target pH
Alkalinity (mg/L as CaCO3)	Target pH
0-60	5.5
>60-120	6.3
>120-240	7.0
>240	7.5

(D) For waters with alkalinities of less than sixty (60) milligrams per liter for which the addition of small amounts of alum or equivalent addition of iron coagulant drives the pH below five and five-tenths (5.5) before significant TOC removal occurs, the system shall add necessary chemicals to maintain the pH between five and three-tenths (5.3) and five and seven-tenths (5.7) in samples until the TOC removal of three-tenths (0.3) milligram per liter per ten (10) milligrams per liter alum added, or equivalent addition of iron coagulant, is reached.

(E) The system may operate at any coagulant dose or pH necessary, consistent with, the provisions of 327 IAC 8-2, 327 IAC 8-2.5, and 327 IAC 8-2.6, to achieve the minimum TOC percent removal approved under subdivision (3).

(F) If the TOC removal is consistently less than three-tenths (0.3) milligram per liter of TOC per ten (10) milligrams per liter of incremental alum dose at all dosages of alum (or equivalent addition of iron coagulant), then the:

(i) water is deemed to contain TOC not amenable to enhanced coagulation; and

(ii) system may apply to the commissioner for a waiver of enhanced coagulation requirements.

  (c) Compliance calculations are required as follows:

(1) Subpart H systems other than those identified in subsection (a)(2) or (a)(3) shall comply with requirements contained in subsection (b)(2) or (b)(3). Systems shall calculate compliance quarterly, beginning after the system has collected twelve (12) months of data, by determining an annual average using the following method:

STEP 1: Calculate actual monthly TOC percent removal, which is equal to: (1 - (treated water TOC/source water TOC)) ´ one hundred (100).

STEP 2: Calculate the required monthly TOC percent removal (from either the table in subsection (b)(2) or from subsection (b)(3)).

STEP 3: Divide the value determined under STEP 1 by the value determined under STEP 2.

STEP 4: Add together the quotients determined under STEP 3 for the last twelve (12) months and divide by twelve (12).

STEP 5: If the quotient calculated in STEP 4 is less than one and zero-hundredths (1.00), the system is not in compliance with the TOC percent removal requirements.

(2) Systems may use one (1) or more of the following provisions instead of the calculations in subdivision (1) to determine compliance with TOC percent removal requirements:

(A) In any month that the system's treated or source water TOC level, measured according to section 5(d)(3) of this rule, is less than two and zero-tenths (2.0) milligrams per liter, the system may assign a monthly value of one and zero-tenths (1.0) (instead of the value calculated in STEP 3 of subdivision (1)) when calculating compliance under subdivision (1).

(B) In any month that a system practicing softening removes at least ten (10) milligrams per liter of magnesium hardness (as CaCO₃), the system may assign a monthly value of one and zero-tenths (1.0) (instead of the value calculated in STEP 3 of subdivision (1)) when calculating compliance under subdivision (1).

(C) In any month that the system's source water SUVA, before any treatment and measured according to section 5(d)(4) of this rule, is less than or equal to two and zero-tenths (2.0) liters per milligram meter, the system may assign a monthly value of one and zero-tenths (1.0) (instead of the value calculated in STEP 3 of subdivision (1)) when calculating compliance under subdivision (1).

(D) In any month that the system's finished water SUVA, measured according to section 5(d)(4) of this rule, is less than or equal to two and zero-tenths (2.0) liters per milligram meter, the system may assign a monthly value of one and zero-tenths (1.0) (instead of the value calculated in STEP 3 of subdivision (1)) when calculating compliance under subdivision (1).

(E) In any month that a system practicing enhanced softening lowers alkalinity below sixty (60) milligrams per liter (as CaCO₃), the system may assign a monthly value of one and zero-tenths (1.0) (instead of the value calculated in STEP 3 of subdivision (1)) when calculating compliance under subdivision (1).

(3) Subpart H systems using conventional treatment may also comply with this section by meeting the criteria in subsection (a)(2) or (a)(3).

  (d) The commissioner identifies the following as treatment techniques for Subpart H systems using conventional treatment to control the level of disinfection byproduct precursors in drinking water treatment and distribution systems:

(1) Enhanced coagulation.

(2) Enhanced softening.

(Water Pollution Control Division; 327 IAC 8-2.5-9; filed May 1, 2003, 12:00 p.m.: 26 IR 2851; filed Oct 24, 2006, 3:03 p.m.: 20061122-IR-327050255FRA; filed May 7, 2010, 9:30 a.m.: 20100602-IR-327080198FRA)