| (a) Applicability. All community water systems shall
comply with the requirements of this section regarding radionuclide
contaminants. Public water systems treating groundwater under the
direct influence of surface water must comply with the radionuclide
requirements for surface water systems. Public water systems shall
comply with the initial monitoring requirements.
(b) Maximum contaminant levels (MCL). The concentration
of radionuclide contaminants in the water entering the distribution
system shall not exceed the following MCLs.
(1) MCLs for naturally occurring radionuclides are
as follows:
(A) 5 picoCuries per liter (pCi/L) for combined radium-226
and radium-228, as calculated by the summation of the results for
radium-226 and radium-228;
(B) 15 pCi/L for gross alpha particle activity (including
radium-226 but excluding radon and uranium); and
(C) 30 micrograms per liter for uranium.
(2) MCLs for beta particle and photon radioactivity
from man-made radionuclides in drinking water in community water systems
are equivalent to the MCLs under 40 Code of Federal Regulations (CFR) §141.66(d),
as amended and adopted in the CFR through December 7, 2000 (65 FR
76708), which is adopted by reference.
(c) Monitoring requirements. Public water systems shall
measure the concentration of radionuclides at locations and frequencies
specified in the system's monitoring plan. All samples must be collected
during normal operating conditions.
(1) Monitoring frequency for naturally occurring radionuclides.
The monitoring frequency requirements for gross alpha particle activity,
combined radium-226 and radium-228, and uranium are as follows.
(A) Initial monitoring frequency. All systems that
use a new source of water must begin to conduct initial monitoring
of the new source within 90 days after initiating use of the source.
(i) If the initial monitoring results are at or above
an MCL, the system must perform quarterly monitoring as described
in subparagraph (C) of this paragraph.
(ii) If the initial monitoring results are below all
of MCLs given in subsection (b)(1) of this section, the system shall
perform routine monitoring as described in subparagraph (B) of this
paragraph.
(B) Routine monitoring. The results of samples collected
during initial and routine monitoring periods will be used to determine
the monitoring frequency for subsequent monitoring periods.
(i) If the results for all contaminants (gross alpha
particle activity, combined radium-226 and radium-228, and uranium)
are below the detection limits specified in Table A of this clause,
the system must collect and analyze at least one sample at that sampling
point once every nine years.
Attached Graphic
(ii) If the result for any contaminant is at or above
the detection limit but at or below one-half the MCLs given in subsection
(b) of this section, the system must collect and analyze at least
one sample at that sampling point every six years.
(iii) If the result for any contaminant is above one-half
the MCLs given in subsection (b) of this section but below the MCL,
the system must collect and analyze at least one sample at that sampling
point every three years.
(iv) If the result for any contaminant is at or above
any of the MCLs given in subsection (b) of this section, monitoring
must be performed at the frequency given in subparagraph (C) of this
paragraph.
(C) Increased monitoring. A system must perform increased
monitoring if any results at a sampling point are at or above the
MCLs, or at the direction of the executive director.
(i) If the results for any contaminant are at or above
any of the MCLs given in subsection (b) of this section, consecutive
quarterly monitoring must be performed at that sample point.
(ii) If the average of quarterly monitoring results
is less than the MCLs in subsection (b) of this section, the sample
point may be returned to the routine sampling frequency given in subparagraph
(B) of this paragraph.
(iii) To fulfill quarterly monitoring requirements
a system may composite up to four consecutive quarterly samples from
a single entry point if analysis is done within a year of the first
sample.
(iv) The analytical results from a composite sample
will be treated as the annual average to determine compliance with
the MCLs and future monitoring frequency requirements.
(v) When required by the executive director, more frequent
monitoring must be conducted in the vicinity of mining or other operations
that may contribute alpha particle radioactivity to either surface
or groundwater sources of drinking water, or when changes in the distribution
system or treatment processing occur that may increase the concentration
of radionuclide in the finished water.
(vi) Community public water systems shall conduct monitoring
when required by the executive director.
(D) Historical data. A system may use historical data
to comply with the initial monitoring requirement, if approved by
the executive director.
(i) A system having only one entry point to the distribution
system may use the monitoring data from the previous entry point or
distribution system compliance monitoring to satisfy initial monitoring
requirements.
(ii) A system with multiple entry points that has appropriate
historical monitoring data for each entry point to the distribution
system may use previous compliance monitoring data to satisfy initial
monitoring requirements.
(iii) To satisfy initial monitoring requirements, a
community water system with appropriate historical data for a representative
point in the distribution system may use the monitoring data from
the distribution system, provided that the executive director finds
that the historical data satisfactorily demonstrates that each entry
point to the distribution system is expected to be in compliance based
upon the historical data and reasonable assumptions about the variability
of contaminant levels between entry points.
(E) Sample invalidation. The executive director may
invalidate the results of obvious sampling or analytic errors.
(F) Confirmation samples. The executive director may
require more frequent monitoring or may require confirmation samples
at the executive director's discretion.
(G) Sampling scheduling. Systems shall monitor at the
time designated by the executive director.
(2) Monitoring and compliance for man-made radionuclides.
The monitoring and compliance requirements for man-made radionuclide
under 40 CFR §141.26(b), as amended and adopted in the CFR through
December 7, 2000 (65 FR 76708), are adopted by reference.
(3) Monitoring locations for radionuclide contaminants.
Systems must monitor at sample sites described in the system's monitoring
plan.
(A) Initial monitoring for a new water source must
be conducted at a site representative of the water quality of the
new source of water.
(B) Routine compliance monitoring for the radionuclide
covered by this section must be performed at sampling points representing
each entry point to the distribution system. If results from an entry
point exceed one-half the MCL, the executive director may require
the system to sample all water sources providing water to that entry
point.
(d) Analytical requirements for radionuclide contaminants.
Analytical procedures shall be performed in accordance with §290.119
of this title (relating to Analytical Procedures). Testing for radionuclide
contaminants shall be performed at a laboratory certified by the executive
director.
(e) Reporting requirements. The owner or operator of
a public water system must ensure the executive director is provided
with a copy of the results of any test, measurement, or analysis required
by this section. The copies must be submitted within the first ten
days following the month in which the result is received by the public
water system, or the first ten days following the end of the required
monitoring period as provided by this subsection, whichever occurs
first. The copies must be mailed to the Water Supply Division, MC
155, Texas Commission on Environmental Quality, P.O. Box 13087, Austin,
Texas 78711-3087.
(f) Compliance determination. Compliance with the requirements
of this section shall be determined as follows.
(1) If the running average annual MCL for gross alpha
particle activity, combined radium-226 and radium-228, or uranium
as set forth in subsection (b) of this section is exceeded, based
on quarterly monitoring results, the system has committed an MCL violation.
(A) A gross alpha particle activity measurement may
be substituted for the required radium-226 and radium-228 analysis
provided that the measured gross alpha particle activity does not
exceed 5 pCi/L at a confidence level of 95% (1.65 theta where theta
is the standard deviation of the net counting rate of the sample).
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