Current through Register 2024 Notice Reg. No. 38, September 20, 2024
(a)
Each community and nontransient-noncommunity water system (system) shall comply
with the primary MCLs in Table 64442 in the drinking water supplied to the
public and use the DLRs for reporting monitoring results:
Table 64442
Radionuclide Maximum Containment Levels (MCLs) and
Detection Levels for Purposes of Reporting (DLRs)
|
Radionuclide |
MCL | |
DLR |
| Radium-226 |
| |
1 pCi/L |
| Radium-228 |
5 pCi/L (combined radium-226 & -228) | |
1 pCi/L |
| Gross Alpha particle activity (excluding radon and
uranium) |
15 pCi/L | |
3 pCi/L |
| Uranium |
20 pCi/L | |
1 pCi/L |
(b)
Each system shall monitor to determine compliance with the MCLs in table 64442,
as follows:
(1) Monitor at each water source,
or every entry point to the distribution system that is representative of all
sources being used under normal operating conditions; conduct all monitoring at
the same sample site(s) unless a change is approved by the State Board, based
on a review of the system and its historical water quality data;
(2) For quarterly monitoring, monitor during
the same month (first, second or third) of each quarter during each quarter
monitored;
(3) By December 31,
2007, complete initial monitoring that consists of four consecutive quarterly
samples at each sampling site for each radionuclide in table 64442, except that
nontransient-noncommunity water systems shall not be required to monitor
radium-228 as a separate analyte, but shall monitor for compliance with the
combined radium MCL using the analytical method described in Prescribed
Procedures for Measurement of Radioactivity in Drinking Water, Section 6,
Alpha-Emitting Radium Isotopes in Drinking Water, method 903.0
(EPA/600/4-80-032, August, 1980):
(A) Data
collected for a sampling site between January 1, 2001, and December 31, 2004,
may be used to satisfy the initial monitoring requirement, subject to the State
Board's approval based on whether the analytical methods, DLRs, sampling sites,
and the frequency of monitoring used were consistent with this
article.
(B) For gross alpha
particle activity, uranium, radium-226 and radium-228, the State Board may
waive the final two quarters of initial monitoring at a sampling site if the
results from the previous two quarters are below the DLR(s) and the sources are
not known to be vulnerable to contamination.
(c) Any new system or new source for an
existing system shall begin monitoring pursuant to Subsection (b) within the
first quarter after initiating water service to the public.
(d) After initial monitoring, each system
shall monitor for each radionuclide at each sampling site at a frequency
determined by the monitoring result(s) [single sample result or average of
sample results if more than one sample collected] from the most recent
compliance period as follows:
(1) For
nontransient-noncommunity water systems, the results for the total radium
analyses shall be averaged.
(2) For
community water systems, the results of radium-226 and radium-228 analyses
shall be added and the average calculated.
(3) The values used for the radionuclide MCLs
and DLRs shall be as specified in Table 64442.
(4) If the single sample result or average
is:
A. Below the DLR, the system shall
collect and analyze at least one sample every nine years (3 compliance
periods).
B. At or above the DLR,
but at or below 1/2 the MCL, the system shall collect and analyze at least one
sample every six years.
C. Above
1/2 the MCL, but not above the MCL, the system shall collect and analyze at
least one sample every three years.
(e) A system that monitors quarterly may
composite up to four consecutive samples from a single sampling site if
analysis is done within a year of the first sample's collection. If the result
of the composited sample is greater than 1/2 the MCL, at least one additional
quarterly sample shall be analyzed to evaluate the range and trend of results
over time before allowing the system to reduce the monitoring
frequency.
(f) A gross alpha
particle activity measurement may be substituted for other measurements by
adding the 95% confidence interval (1.65[SIGMA], where [SIGMA] is the standard
deviation of the net counting rate of the sample) to it; and if,
(1) For uranium and radium measurements
(after initial radium-228 monitoring has been completed), the gross alpha
measurement does not exceed 5 pCi/L; or
(2) For radium measurements (after initial
radium-228 monitoring has been completed), the result obtained from subtracting
the uranium measurement from the gross alpha measurement does not exceed 5
pCi/L.
(g) If any sample
result is greater than an MCL:
(1) For a
system monitoring less than quarterly, quarterly samples shall be collected and
analyzed to determine compliance, pursuant to subsection (h);
(2) For a system that already has four
consecutive quarterly results, compliance shall be determined pursuant to
subsection (h).
(3) The system
shall monitor quarterly until the results of four consecutive quarterly sample
results do not exceed the MCL.
(h) A system with one or more sample results
greater than an MCL shall determine compliance with the MCL as follows:
(1) At each sampling site, based on the
analytical results for that site. Any confirmation sample result shall be
averaged with the initial result.
(2) Using all monitoring results collected
under this section during the previous 12 months, even if more than the minimum
required number of samples was collected.
(3) By a running annual average of four
consecutive quarters of sampling results. Averages shall be rounded to the same
number of significant figures as the MCL for which compliance is being
determined.
(A) If any sample result will
cause the annual average at any sample site to exceed the MCL, the system shall
be out of compliance immediately upon receiving the result;
(B) If a system has not analyzed the required
number of samples, compliance shall be determined by the average of the samples
collected at the site during the most recent 12 months; and
(C) If a sample result is less than the DLR
in table 64442, zero shall be used to calculate the annual average, unless a
gross alpha particle activity is being used in lieu of radium-226, total
radium, and/or uranium. In that case, if the gross alpha particle activity
result is less than the DLR, 1/2 the DLR shall be used to calculate the annual
average.
(4) If
compositing is allowed at a sampling site, by the results of a composite of
four consecutive quarterly samples.
(5) If the system can provide documentation
that a sample was subject to sampling or analytical errors, the State Board may
invalidate the result based on its review of the documentation, the sampling
result, and the historical sampling data.
(6) Each system shall ensure that the
laboratory analyzing its samples collected for compliance with this article
calculates and reports the sample-specific Minimum Detectable Activity at the
95% confidence level (MDA95) along with the sample
results. The MDA95 shall not exceed the DLR and shall be
calculated as described in ANSI N42.23 Measurement and Associated
Instrumentation Quality Assurance for Radiobioassay Laboratories, Appendix
A.7.6 (September 10, 1995).
1. New
section filed 5-12-2006; operative 6-11-2006 (Register 2006, No.
19).
2. Change without regulatory effect amending subsections
(b)(1), (b)(3)(A)-(B) and (h)(5) and amending NOTE filed 6-2-2015 pursuant to
section 100, title 1, California Code of
Regulations (Register 2015, No. 23).
Note: Authority cited: Sections
116271,
116325,
116350
and
116375,
Health and Safety Code. Reference: Sections
116275,
116365
and
116385,
Health and Safety Code.
