Cal. Code Regs. tit. 22, § 64534.2 – Disinfection Byproducts Monitoring.

(a) Community and nontransient noncommunity water systems shall monitor for TTHM and HAA5 at the frequencies and locations indicated in table 64534.2-A.
1. (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, ≤ 4.0 mg/L
  ≥10,000
  TTHM¹ ≤0.040 mg/L and HAA5¹ ≤0.030 mg/L
  One sample per treatment plant per quarter at distribution system location reflecting maximum residence time.
  500-9,999
  TTHM¹ ≤0.040 mg/L and HAA5¹ ≤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 ≤0.040 mg/L and HAA5¹ ≤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 ≤0.040 mg/L and HAA5¹ ≤0.030 mg/L for the system may reduce monitoringif it has monitored at least one
  One sample per treatment plant per three-year monitoring cycle at distribution system
  two consecutive years OR TTHM¹ ≤0.020 mg/L and HAA5¹ ≤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. (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. (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 ≤0.060 mg/L and HAA5 annual average is ≤0.045 mg/L.
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.
(b) Community and nontransient noncommunity water systems using chlorine dioxide shall conduct monitoring for chlorite as follows:
1. (1) Systems shall take daily samples at the entrance to the distribution system and analyze the samples the same day the samples are taken. For any daily sample that exceeds the chlorite MCL, the system shall take three additional chlorite distribution system samples the following day (in addition to the daily sample required at the entrance to the distribution system) at these locations: as close to the first customer as possible, at a location representative of average residence time, and at a location reflecting maximum residence time in the distribution system. The system shall analyze the additional samples within 48 hours of being notified pursuant to section 64537(b) of the exceedance;
2. (2) Systems shall take a three-sample set each month in the distribution system. The system shall take one sample at each of the following locations: as close to the first customer as possible, at a location representative of average residence time, and at a location reflecting maximum residence time in the distribution system. Any additional routine sampling shall be conducted in the same manner (as three-sample sets, at the specified locations). The system may use the results of additional monitoring conducted under paragraph (1) to meet the monitoring requirement in this paragraph;
3. (3) Systems may apply to the State Board to reduce monthly chlorite monitoring in the distribution system pursuant to paragraph (2) to one three-sample set per quarter after one year of monitoring during which no individual chlorite sample taken in the distribution system has exceeded the chlorite MCL and the system has not been required to conduct additional monitoring under paragraph (1). The application shall include the results of all chlorite 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 and determine whether or not the system is eligible to reduce monitoring to one three-sample set per quarter. The system may remain on the reduced monitoring schedule until either any of the three individual chlorite samples taken quarterly in the distribution system under paragraph (2) exceeds the chlorite MCL or the system is required to conduct additional monitoring under paragraph (1), at which time the system shall revert to routine monitoring; and
4. (4) If a distribution system sample taken pursuant to paragraph (2) exceeds the chlorite MCL, the system shall take and analyze a confirmation sample within 48 hours of being notified pursuant to section 64537(c) of the exceedance. If the system fails to take a confirmation sample pursuant to this paragraph, it shall take and analyze a confirmation sample within two weeks of notification of the results of the first sample.
(c) Community and nontransient noncommunity systems using ozone shall monitor for bromate as follows:
1. (1) Systems shall take one sample per month for each treatment plant in the system using ozone. Samples shall be taken at the entrance to the distribution system while the ozonation system is operating under normal conditions;
2. (2) Systems may reduce bromate monitoring from monthly to once per quarter, if the system's running annual average bromate concentration is ≤0.0025 mg/L based on monthly bromate measurements under paragraph (1) for the most recent four quarters, with samples analyzed using Method 317.0 Revision 2.0, 321.8, or 326.0. The system shall notify the State Board in writing within 30 days of the change in monitoring frequency; and
3. (3) Systems shall resume routine bromate monitoring pursuant to paragraph (1) and notify the State Board in writing within 30 days of the change in monitoring frequency if the running annual average bromate concentration, computed quarterly, is greater than 0.0025 mg/L.
(d) By the applicable date specified in section 64530(d), and in lieu of TTHM and HAA5 monitoring in subsection (a):
1. (1) Community and nontransient noncommunity water systems shall monitor for TTHM and HAA5 at the frequencies and location totals indicated in table 64534.2-C and in accordance with the monitoring plan developed pursuant to section 64534.8;
  Table 64534.2-C Routine Monitoring Frequency for TTHM and HAA5
  Minimum monitoring frequency¹
  Source water type
  Persons served
  Number of distribution system monitoring locations
  Monitoring period²
  Systems using approved surface water
  ≥5,000,000
  20 dual sample sets
  per quarter
  1,000,000-4,999,999
  16 dual sample sets
  per quarter
  250,000-999,999
  12 dual sample sets
  per quarter
  50,000-249,999
  8 dual sample sets
  per quarter
  10,000-49,999
  4 dual sample sets
  per quarter
  3,301-9,999
  2 dual sample sets
  per quarter
  500-3,300
  1 TTHM and 1 HAA5 sample: one at the location with the highest TTHM measurement, one at the location with the highest HAA5 measurement
  per quarter
  <500
  1 TTHM and 1 HAA5 sample: one at the location with the highest TTHM measurement, one at the location with the highest HAA5 measurement³
  per year
  Systems using ground water not under direct influence of surface water
  ≥500,000
  8 dual sample sets
  per quarter
  100,000-499,999
  6 dual sample sets
  per quarter
  10,000-99,999
  4 dual sample sets
  per quarter
  500-9,999
  2 dual sample sets
  per year
  <500
  1 TTHM and 1 HAA5 sample: one at the location with the highest TTHM measurement, one at the location with the highest HAA5 measurement³
  per year
  ¹ All systems shall monitor during the month of highest disinfection byproduct concentrations.
  ² Systems on quarterly monitoring shall take dual sample sets every 90 days at each monitoring location, except for systems using approved surface water and serving 500-3,300 persons.
  ³ Only one location with a dual sample set per monitoring period is needed if highest TTHM and HAA5 concentrations occur at the same location and month.
2. (2) Undisinfected systems that begin using a disinfectant other than UV light after the applicable dates in 40 Code of Federal Regulations, part 141.600 (71 Fed. Reg. 388, January 4, 2006), which is incorporated by reference, shall consult with the State Board to identify compliance monitoring locations for this subsection. Systems shall then develop a monitoring plan in accordance with section 64534.8 that includes those monitoring locations;
3. (3) Systems may apply to the State Board to monitor at a reduced frequency in accordance with table 64534.2-D, any time the LRAA is ≤0.040 mg/L for TTHM and ≤0.030 mg/L for HAA5 at all monitoring locations. In addition, the source water annual average TOC level, before any treatment shall be ≤4.0 mg/L at each treatment plant treating approved surface water, based on source water TOC monitoring conducted pursuant to section 64534.6. 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-D;
  Table 64534.2-D Reduced Monitoring Frequency for TTHM and HAA5
  Minimum monitoring frequency
  Source water type
  Persons served
  Number of distribution system monitoring locations
  Monitoring period¹
  Systems using approved surface water
  ≥5,000,000
  10 dual sample sets: at the locations with the five highest TTHM and five highest HAA5 LRAAs
  per quarter
  1,000,000-4,999,999
  8 dual sample sets: at the locations with the four highest TTHM and four highest HAA5 LRAAs
  per quarter
  250,000-999,999
  6 dual sample sets: at the locations with the three highest TTHM and three highest HAA5 LRAAs
  per quarter
  50,000-249,999
  4 dual sample sets: at the locations with the two highest TTHM and two highest HAA5 LRAAs
  per quarter
  10,000-49,999
  2 dual sample sets: at the locations with the highest TTHM and highest HAA5 LRAAs
  per quarter
  3,301-9,999
  2 dual sample sets: one at the location and during the quarter with the highest TTHM single measurement, one at the location and during the quarter with the highest HAA5 single measurement
  per year
  500-3,300
  1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement, one at the location and during the quarter with the highest HAA5 single measurement; 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter
  per year
  Systems using only ground water not under direct influence of surface water
  ≥500,000
  4 dual sample sets: at the locations with the two highest TTHM and two highest HAA5 LRAAs
  per quarter
  100,000-499,999
  2 dual sample sets: at the locations with the highest TTHM and highest HAA5 LRAAs
  per quarter
  10,000-99,999
  2 dual sample sets: one at the location and during the quarter with the highest TTHM single measurement, one at the location and during the quarter with the highest HAA5 single measurement
  per year
  500-9,999
  1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement, one at the location and during the quarter with the highest HAA5 single measurement; 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter
  per year
  <500
  1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement, one at the location and during the quarter with the highest HAA5 single measurement; 1 dual sample set every third year if the highest TTHM and HAA5 measurements occurred at the same location and quarter
  every third year
  ¹ Systems on quarterly monitoring shall take dual sample sets every 90 days.
4. (4) Systems on reduced monitoring shall resume routine monitoring pursuant to table 64534.2-C or conduct increased monitoring pursuant to paragraph (5) (if applicable), if the TTHM LRAA is >0.040 mg/L or the HAA5 LRAA is >0.030 mg/L at any monitoring location (for systems with quarterly reduced monitoring); a TTHM sample is >0.060 mg/L or a HAA5 sample is >0.045 mg/L (for systems with annual or less frequent monitoring); or the source water annual average TOC level, before any treatment, is >4.0 mg/L at any treatment plant treating an approved surface water;
5. (5) Systems that are required to monitor at a particular location annually or less frequently than annually pursuant to table 64534.2-C or 64534.2-D shall increase monitoring to dual sample sets once per quarter (taken every 90 days) at all locations if a TTHM sample is >0.080 mg/L or a HAA5 sample is >0.060 mg/L at any location. Systems on increased monitoring may return to routine monitoring specified in table 64534.2-C if, after at least four consecutive quarters of monitoring, the LRAA for every monitoring location is ≤0.060 mg/L for TTHM and ≤0.045 mg/L for HAA5;
6. (6) If the operational evaluation level (OEL) exceeds 0.080 mg/L for TTHM or 0.060 mg/L for HAA5 at any monitoring location, systems shall conduct an operational evaluation. The operational evaluation shall include the examination of system treatment and distribution operational practices, including storage tank operations, excess storage capacity, distribution system flushing, changes in sources or source water quality, and treatment changes or problems that may contribute to TTHM and HAA5 formation and what steps could be considered to minimize future exceedances. Systems that are able to identify the cause of the OEL exceedance may submit a written request to the State Board to limit the scope of the evaluation. The request to limit the scope of the evaluation shall not extend the schedule in section 64537(d) for submitting the written report to the State Board;
7. (7) Systems on reduced monitoring pursuant to table 64534.2-B may remain on reduced monitoring after the applicable date in table 64530-A for compliance with this subsection provided the system meets IDSE requirements under section 64530(c) by qualifying for a 40/30 certification (40 CFR part 141.603) or receiving a very small system waiver (40 CFR part 141.604), meets the reduced monitoring criteria in paragraphs (3) and (4), and does not change or add monitoring locations from those used for compliance monitoring under subsection (a); and
8. (8) Systems on increased monitoring pursuant to table 64534.2-A shall remain on increased monitoring and conduct increased monitoring pursuant to paragraph (5) at the locations in the monitoring plan developed under section 64534.8 beginning at the applicable date in table 64530-A for compliance with this subsection. Systems on increased monitoring may return to routine monitoring specified in table 64534.2-C pursuant to paragraph (5).

Note: Authority cited: Sections 116271, 116350 and 116375, Health and Safety Code. Reference: Sections 116350, 116385 and 116555, Health and Safety Code.

History

1. New section filed 5-18-2006; operative 6-17-2006 (Register 2006, No. 20).

2. Editorial correction of Table 64534.2-B (Register 2007, No. 30).

3. Amendment of subsections (a)(2) and (b)(1)-(3), new subsection (b)(4), amendment of subsections (c)(1)-(2), new subsections (c)(3)-(d)(8) and amendment of Note filed 5-22-2012; operative 6-21-2012 (Register 2012, No. 21).

4. Amendment of subsections (a)(2). (c)(2) and (c)(3), repealer of subsections (c)(3)(A)-(B) and amendment of subsection (d)(2) filed 5-28-2014; operative 7-1-2014 (Register 2014, No. 22).

5. Change without regulatory effect amending subsections (a)(1), (b)(3), (c)(2)-(3), (d)(2)-(3) and (d)(6) and amending Note filed 6-2-2015 pursuant to section 100, title 1, California Code of Regulations (Register 2015, No. 23).

6. Editorial correction of Table 64534.2-D within subsection (d)(3) (Register 2021, No. 33).