California Code of Regulations › Title 22 - Social Security › Division 4 - Environmental Health › Chapter 15.5 - Disinfectant Residuals, Disinfection Byproducts, and Disinfection Byproduct Precursors › Article 5 - Treatment Technique for Control of Disinfection Byproduct Precursors (Dbpp) › Section 64536.2 - Enhanced Coagulation and Enhanced Softening Performance Requirements

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
(a) Systems using
				  approved surface water and conventional filtration treatment (as defined in
				  section 64651.23) shall operate with
				  enhanced coagulation or enhanced softening to achieve the TOC percent removal
				  levels specified in this section, unless the system meets at least one of the
				  alternative compliance criteria listed in section
				  64536(a) or
				  (b).
(b) Systems shall achieve the Step 1 percent
				  reduction of TOC specified in table 64536.2-A between the source water and the
				  combined filter effluent, unless the State Board approves a system's request
				  for alternate minimum TOC removal (Step 2) requirements under subsection (c).
				  Systems practicing softening shall meet the Step 1 TOC removals in the
				  far-right column (Source water alkalinity >120 mg/L) of table 64536.2-A for
				  the specified source water TOC:
Table 64536.2-A
Step 1 Required Removal of TOC by Enhanced
					 Coagulation and Enhanced Softening Systems Using Conventional
					 Treatment
1, 2
Required
							 Removal of TOC
Source-Water
Source-Water Alkalinity, mg/L as CaCO3
TOC,mg/L
0-60
>60-120
>120
>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%
1 Systems that meet one of the
					 criteria in section
					 64536(a),
					 paragraphs (1) through (6) do not have to operate with enhanced
					 coagulation.
2 Softening systems that meet
					 one of the criteria in section
					 64536(b),
					 paragraphs (1) through (2) do not have to operate with enhanced
					 softening.
(c) Systems using
				  approved surface water and conventional treatment that cannot achieve the Step
				  1 TOC removals required by subsection (b) due to water quality parameters or
				  operational constraints shall apply to the State Board, within three months of
				  failure to achieve the TOC removals required by subsection (b), for approval of
				  Step 2 removal requirements. If the State Board approves the Step 2 removal
				  requirements pursuant to subsection (d), and the system conducted monthly TOC
				  monitoring beginning one year prior to the compliance date specified in section
				  64530, the Step 2 removal
				  requirements will be retroactive to the compliance date for the purposes of
				  determining compliance.
(d)
				  Applications made to the State Board by systems using enhanced coagulation for
				  approval of Step 2 removal requirements under subsection (c) shall include, as
				  a minimum, results of bench-scale or pilot-scale testing conducted under
				  paragraph (1) of this subsection that were used to determine the alternate
				  enhanced coagulation level.
(1) Alternate
				  enhanced coagulation level is defined as coagulation at a coagulant dose and pH
				  as determined by the method described in paragraphs (1) through (4) such that
				  an incremental addition of 10 mg/L of alum (or equivalent addition of iron
				  coagulant) results in a TOC removal of <0.3 mg/L. The percent removal of TOC
				  at this point on the "TOC removal versus coagulant dose" curve is then defined
				  as the Step 2 removal requirement for the system. Once approved by the State
				  Board, this Step 2 removal requirement supersedes the minimum TOC removal
				  required by section
				  64536.2(b). This
				  requirement shall be effective until such time as the State Board approves a
				  new value based on the results of a new bench-scale or pilot-scale
				  test.
(2) Bench-scale or
				  pilot-scale testing of enhanced coagulation shall be conducted by using
				  representative water samples and adding 10 mg/L increments of alum (or
				  equivalent addition of iron coagulant) until the pH is reduced to a level less
				  than or equal to the enhanced coagulation Step 2 target pH shown in table
				  64536.2-B.
Table 64536.2-B 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
(3)
				  For waters with alkalinities of less than 60 mg/L for which the addition of
				  small amounts of alum (or equivalent addition of iron coagulant) drives the pH
				  below 5.5 before significant TOC removal occurs, the system shall add necessary
				  chemicals to maintain the pH between 5.3 and 5.7 in samples until the TOC
				  removal of 0.3 mg/L per 10 mg/L alum added (or equivalent addition of iron
				  coagulant) is reached.
(4) If the
				  TOC removal is consistently less than 0.3 mg/L of TOC per 10 mg/L of
				  incremental alum dose at all dosages of alum (or equivalent addition of iron
				  coagulant), the system is eligible to apply for a waiver of enhanced
				  coagulation requirements. The application shall include, as a minimum, the
				  results of bench-scale or pilot-scale testing conducted under paragraph (1) of
				  this subsection.