California Code of Regulations › Title 22 - Social Security › Division 4 - Environmental Health › Chapter 15.5 - Disinfectant Residuals, Disinfection Byproducts, and Disinfection Byproduct Precursors › Article 3 - Monitoring Requirements › Section 64534.2 - Disinfection Byproducts Monitoring

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
(a) Community and nontransient noncommunity
				  water systems shall monitor for TTHM and HAA5 at the frequencies and locations
				  indicated in table 64534.2-A.
Table 64534.2-A Routine and Increased Monitoring
					 Frequency for TTHM and HAA5
COLUMN A Type of
							 System
COLUMN B Persons
							 served
COLUMN C Minimum monitoring
							 frequency
COLUMN D Sample location in the
							 distribution system & increased monitoring frequencies
Systems using approved surface
							 water
>=10,000
Four samples per quarter per treatment
							 plant
At least 25 percent of all samples collected each quarter at
							 locations representing maximum residence time. Remaining samples taken at
							 locations representative of at least average residence time in the distribution
							 system and representing the entire distribution system, taking into account
							 number of persons served, different sources of water, and different treatment
							 methods1.
500-9,999
One sample per quarter
							 per treatment plant
Locations representing maximum residence
							 time1.
<500
One sample per year per
							 treatment plant during month of warmest water temperature
Locations
							 representing maximum residence time1. If the sample
							 (or average of annual samples, if more than one sample is taken) exceeds MCL,
							 system shall increase monitoring to one sample per treatment plant per quarter,
							 taken at a point reflecting the maximum residence time in the distribution
							 system, until system meets reduced monitoring criteria in paragraph (3) of this
							 subsection.
Systems using only ground water not under direct
							 influence of surface water and using chemical
							 disinfectant
>=10,000
One sample per quarter per treatment
							 plant
Locations representing maximum residence
							 time1.
<10,000
One sample per year per
							 treatment plant during month of warmest water temperature
Locations
							 representing maximum residence time1. If the sample
							 (or average of annual samples, if more than one sample is taken) exceeds MCL,
							 system shall increase monitoring to one sample per treatment plant per quarter,
							 taken at a point reflecting the maximum residence time in the distribution
							 system, until system meets reduced monitoring criteria in paragraph (3) of this
							 subsection.
1 If a system
							 elects to sample more frequently than the minimum required, at least 25 percent
							 of all samples collected each quarter (including those taken in excess of the
							 required frequency) shall be taken at locations that represent the maximum
							 residence time of the water in the distribution system. The remaining samples
							 shall be taken at locations representative of at least average residence time
							 in the distribution system.
(1) Systems
				  may apply to the State Board to monitor at a reduced frequency in accordance
				  with table 64534.2-B. The application shall include the results of all TOC,
				  TTHM, and HAA5 monitoring conducted in the previous 12 months and the proposed
				  revised monitoring plan as required by section
				  64534.8. The State Board will
				  evaluate data submitted with the application to determine whether or not the
				  system is eligible for the reduced monitoring specified in table 64534.2-B;
Table 64534.2-B Reduced Monitoring Frequency for TTHM
					 and HAA5
the system may reduce
							 monitoring if it has monitored at least one
If the system is
							 a(n)...
serving...
year
							 and...
to this level
Approved surface water system which has a source
							 water TOC1 level, before any treatment, [LESS THAN
							 EQUAL TO] 4.0 mg/L
>=10,000
TTHM1
							 [LESS THAN EQUAL TO]0.040 mg/L and HAA51 [LESS THAN
							 EQUAL TO]0.030 mg/L
One sample per treatment plant per quarter at
							 distribution system location reflecting maximum residence time.
500-9,999
TTHM1 [LESS THAN EQUAL
							 TO]0.040 mg/L and HAA51 [LESS THAN EQUAL TO]0.030
							 mg/L
One sample per treatment plant per year at distribution system
							 location reflecting maximum residence time during month of warmest water
							 temperature.
System using only ground water not under direct
							 influence of surface water and using chemical
							 disinfectant
>=10,000
TTHM1 [LESS
							 THAN EQUAL TO]0.040 mg/L and HAA51 [LESS THAN EQUAL
							 TO]0.030 mg/L
One sample per treatment plant per year at distribution
							 system location reflecting maximum residence time during month of warmest water
							 temperature.
<10,000
TTHM1 [LESS THAN EQUAL TO]0.040
							 mg/L and HAA51 [LESS THAN EQUAL TO]0.030 mg/L for
the system may reduce monitoring
if it has monitored
							 at least one
One sample per treatment plant per three-year
							 monitoring cycle at distribution system
two consecutive years OR
							 TTHM1 [LESS THAN EQUAL TO]0.020 mg/L and
							 HAA51 [LESS THAN EQUAL TO]0.015 mg/L for one
							 year
location reflecting maximum residence time during month of warmest
							 water temperature, with the three-year cycle beginning on January 1 following
							 the quarter in which system qualifies for reduced monitoring.
1 TOC, TTHM,
							 and HAA5 values based on annual averages.
(2)
				  Systems on reduced monitoring shall resume monitoring at the frequency
				  specified in column C of table 64534.2-A in the quarter immediately following
				  the quarter in which the system exceeds 0.060 mg/L for the TTHM annual average,
				  0.045 mg/L for the HAA5 annual average, or 4.0 mg/L for the source water TOC
				  annual average. For systems using only ground water not under the direct
				  influence of surface water and serving fewer than 10,000 persons or for systems
				  using approved surface water and serving fewer than 500 persons, if either the
				  TTHM annual average is >0.080 mg/L or the HAA5 annual average is >0.060
				  mg/L, the system shall go to increased monitoring identified in column D of
				  table 64534.2-A in the quarter immediately following the quarter in which the
				  system exceeds 0.080 mg/L or 0.060 mg/L for the TTHM and HAA5 annual averages,
				  respectively; and
(3) Systems on
				  increased monitoring pursuant to column D of table 64534.2-A may return to
				  routine monitoring specified in column C of table 64534.2-A if, after at least
				  one year of monitoring, TTHM annual average is [LESS THAN EQUAL TO]0.060 mg/L
				  and HAA5 annual average is [LESS THAN EQUAL TO]0.045 mg/L.