[Code of Federal Regulations]
[Title 40, Volume 19]
[Revised as of July 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR141.26]
[Page 375-380]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 141--NATIONAL PRIMARY DRINKING WATER REGULATIONS--Table of Contents
Subpart C--Monitoring and Analytical Requirements
Sec. 141.26 Monitoring frequency for radioactivity in community water systems.
(a) Monitoring requirements for gross alpha particle activity,
radium-226 and radium-228.
[[Page 376]]
(1) Initial sampling to determine compliance with Sec. 141.15 shall
begin within two years of the effective date of these regulations and
the analysis shall be completed within three years of the effective date
of these regulations. Compliance shall be based on the analysis of an
annual composite of four consecutive quarterly samples or the average of
the analyses of four samples obtained at quarterly intervals.
(i) 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/1 at a
confidence level of 95 percent (1.65[sigma] where
[sigma] is the standard deviation of the net counting rate of
the sample). In localities where radium-228 may be present in drinking
water, it is recommended that the State require radium-226 and/or
radium-228 analyses when the gross alpha particle activity exceeds 2
pCi/1.
(ii) When the gross alpha particle activity exceeds 5 pCi/1, the
same or an equivalent sample shall be analyzed for radium-226. If the
concentration of radium-226 exceeds 3 pCi/1 the same or an equivalent
sample shall be analyzed for radium-228.
(2) For the initial analysis required by paragraph (a)(1) of this
section, data acquired within one year prior to the effective date of
this part may be substituted at the discretion of the State.
(3) Suppliers of water shall monitor at least once every four years
following the procedure required by paragraph (a)(1) of this section. At
the discretion of the State, when an annual record taken in conformance
with paragraph (a)(1) of this section has established that the average
annual concentration is less than half the maximum contaminant levels
established by Sec. 141.15, analysis of a single sample may be
substituted for the quarterly sampling procedure required by paragraph
(a)(1) of this section.
(i) More frequent monitoring shall be conducted when ordered by the
State in the vicinity of mining or other operations which may contribute
alpha particle radioactivity to either surface or ground water sources
of drinking water.
(ii) A supplier of water shall monitor in conformance with paragraph
(a)(1) of this section within one year of the introduction of a new
water source for a community water system. More frequent monitoring
shall be conducted when ordered by the State in the event of possible
contamination or when changes in the distribution system or treatment
processing occur which may increase the concentration of radioactivity
in finished water.
(iii) A community water system using two or more sources having
different concentrations of radioactivity shall monitor source water, in
addition to water from a free-flowing tap, when ordered by the State.
(iv) Monitoring for compliance with Sec. 141.15 after the initial
period need not include radium-228 except when required by the State,
Provided, That the average annual concentration of radium-228 has been
assayed at least once using the quarterly sampling procedure required by
paragraph (a)(1) of this section.
(v) Suppliers of water shall conduct annual monitoring of any
community water system in which the radium-226 concentration exceeds 3
pCi/1, when ordered by the State.
(4) If the average annual maximum contaminant level for gross alpha
particle activity or total radium as set forth in Sec. 141.15 is
exceeded, the supplier of a community water system shall give notice to
the State pursuant to Sec. 141.31 and notify the public as required by
subpart Q. Monitoring at quarterly intervals shall be continued until
the annual average concentration no longer exceeds the maximum
contaminant level or until a monitoring schedule as a condition to a
variance, exemption or enforcement action shall become effective.
(b) Monitoring requirements for manmade radioactivity in community
water systems.
(1) Within two years of the effective date of this part, systems
using surface water sources and serving more than 100,000 persons and
such other community water systems as are designated by the State shall
be monitored for compliance with Sec. 141.16 by analysis of
[[Page 377]]
a composite of four consecutive quarterly samples or analysis of four
quarterly samples. Compliance with Sec. 141.16 may be assumed without
further analysis if the average annual concentration of gross beta
particle activity is less than 50 pCi/1 and if the average annual
concentrations of tritium and strontium-90 are less than those listed in
table A, Provided, That if both radionuclides are present the sum of
their annual dose equivalents to bone marrow shall not exceed 4
millirem/year.
(i) If the gross beta particle activity exceeds 50 pCi/1, an
analysis of the sample must be performed to identify the major
radioactive constituents present and the appropriate organ and total
body doses shall be calculated to determine compliance with Sec. 141.16.
(ii) Suppliers of water shall conduct additional monitoring, as
ordered by the State, to determine the concentration of man-made
radioactivity in principal watersheds designated by the State.
(iii) At the discretion of the State, suppliers of water utilizing
only ground waters may be required to monitor for man-made
radioactivity.
(2) For the initial analysis required by paragraph (b)(1) of this
section data acquired within one year prior to the effective date of
this part may be substituted at the discretion of the State.
(3) After the initial analysis required by paragraph (b)(1) of this
section suppliers of water shall monitor at least every four years
following the procedure given in paragraph (b)(1) of this section.
(4) Within two years of the effective date of these regulations the
supplier of any community water system designated by the State as
utilizing waters contaminated by effluents from nuclear facilities shall
initiate quarterly monitoring for gross beta particle and iodine-131
radioactivity and annual monitoring for strontium-90 and tritium.
(i) Quarterly monitoring for gross beta particle activity shall be
based on the analysis of monthly samples or the analysis of a composite
of three monthly samples. The former is recommended. If the gross beta
particle activity in a sample exceeds 15 pCi/1, the same or an
equivalent sample shall be analyzed for strontium-89 and cesium-134. If
the gross beta particle activity exceeds 50 pCi/1, an analysis of the
sample must be performed to identify the major radioactive constituents
present and the appropriate organ and total body doses shall be
calculated to determine compliance with Sec. 141.16.
(ii) For iodine-131, a composite of five consecutive daily samples
shall be analyzed once each quarter. As ordered by the State, more
frequent monitoring shall be conducted when iodine-131 is identified in
the finished water.
(iii) Annual monitoring for strontium-90 and tritium shall be
conducted by means of the analysis of a composite of four consecutive
quarterly samples or analysis of four quarterly samples. The latter
procedure is recommended.
(iv) The State may allow the substitution of environmental
surveillance data taken in conjunction with a nuclear facility for
direct monitoring of manmade radioactivity by the supplier of water
where the State determines such data is applicable to a particular
community water system.
(5) If the average annual maximum contaminant level for man-made
radioactivity set forth in Sec. 141.16 is exceeded, the operator of a
community water system shall give notice to the State pursuant to
Sec. 141.31 and to the public as required by subpart Q. Monitoring at
monthly intervals shall be continued until the concentration no longer
exceeds the maximum contaminant level or until a monitoring schedule as
a condition to a variance, exemption or enforcement action shall become
effective.
[41 FR 28404, July 9, 1976, as amended at 65 FR 26022, May 4, 2000]
Effective Date Note: At 65 FR 76745, Dec. 7, 2000, Sec. 141.26 was
revised, effective Dec. 8, 2003. For the convenience of the user, the
revised text is set forth as follows:
Sec. 141.26 Monitoring frequency and compliance requirements for
radionuclides in community water systems
(a) Monitoring and compliance requirements for gross alpha particle
activity, radium-226, radium-228, and uranium.
(1) Community water systems (CWSs) must conduct initial monitoring
to determine
[[Page 378]]
compliance with Sec. 141.66(b), (c), and (e) by December 31, 2007. For
the purposes of monitoring for gross alpha particle activity, radium-
226, radium-228, uranium, and beta particle and photon radioactivity in
drinking water, ``detection limit'' is defined as in Sec. 141.25(c).
(i) Applicability and sampling location for existing community water
systems or sources. All existing CWSs using ground water, surface water
or systems using both ground and surface water (for the purpose of this
section hereafter referred to as systems) must sample at every entry
point to the distribution system that is representative of all sources
being used (hereafter called a sampling point) under normal operating
conditions. The system must take each sample at the same sampling point
unless conditions make another sampling point more representative of
each source or the State has designated a distribution system location,
in accordance with paragraph (a)(2)(ii)(C) of this section.
(ii) Applicability and sampling location for new community water
systems or sources. All new CWSs or CWSs that use a new source of water
must begin to conduct initial monitoring for the new source within the
first quarter after initiating use of the source. CWSs must conduct more
frequent monitoring when ordered by the State in the event of possible
contamination or when changes in the distribution system or treatment
processes occur which may increase the concentration of radioactivity in
finished water.
(2) Initial monitoring: Systems must conduct initial monitoring for
gross alpha particle activity, radium-226, radium-228, and uranium as
follows:
(i) Systems without acceptable historical data, as defined below,
must collect four consecutive quarterly samples at all sampling points
before December 31, 2007.
(ii) Grandfathering of data: States may allow historical monitoring
data collected at a sampling point to satisfy the initial monitoring
requirements for that sampling point, for the following situations.
(A) To satisfy initial monitoring requirements, a community water
system having only one entry point to the distribution system may use
the monitoring data from the last compliance monitoring period that
began between June 2000 and December 8, 2003.
(B) To satisfy initial monitoring requirements, a community water
system with multiple entry points and having appropriate historical
monitoring data for each entry point to the distribution system may use
the monitoring data from the last compliance monitoring period that
began between June 2000 and December 8, 2003.
(C) 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 last
compliance monitoring period that began between June 2000 and December
8, 2003, provided that the State finds that the historical data
satisfactorily demonstrate 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. The State must make a written finding indicating
how the data conforms to the these requirements.
(iii) For gross alpha particle activity, uranium, radium-226, and
radium-228 monitoring, the State may waive the final two quarters of
initial monitoring for a sampling point if the results of the samples
from the previous two quarters are below the detection limit.
(iv) If the average of the initial monitoring results for a sampling
point is above the MCL, the system must collect and analyze quarterly
samples at that sampling point until the system has results from four
consecutive quarters that are at or below the MCL, unless the system
enters into another schedule as part of a formal compliance agreement
with the State.
(3) Reduced monitoring: States may allow community water systems to
reduce the future frequency of monitoring from once every three years to
once every six or nine years at each sampling point, based on the
following criteria.
(i) If the average of the initial monitoring results for each
contaminant (i.e., gross alpha particle activity, uranium, radium-226,
or radium-228) is below the detection limit specified in Table B, in
Sec. 141.25(c)(1), the system must collect and analyze for that
contaminant using at least one sample at that sampling point every nine
years.
(ii) For gross alpha particle activity and uranium, if the average
of the initial monitoring results for each contaminant is at or above
the detection limit but at or below \1/2\ the MCL, the system must
collect and analyze for that contaminant using at least one sample at
that sampling point every six years. For combined radium-226 and radium-
228, the analytical results must be combined. If the average of the
combined initial monitoring results for radium-226 and radium-228 is at
or above the detection limit but at or below \1/2\ the MCL, the system
must collect and analyze for that contaminant using at least one sample
at that sampling point every six years.
(iii) For gross alpha particle activity and uranium, if the average
of the initial monitoring results for each contaminant is above \1/2\
the MCL but at or below the MCL, the system must collect and analyze at
least one sample at that sampling point every three years. For combined
radium-226 and radium-
[[Page 379]]
228, the analytical results must be combined. If the average of the
combined initial monitoring results for radium-226 and radium-228 is
above \1/2\ the MCL but at or below the MCL, the system must collect and
analyze at least one sample at that sampling point every three years.
(iv) Systems must use the samples collected during the reduced
monitoring period to determine the monitoring frequency for subsequent
monitoring periods (e.g., if a system's sampling point is on a nine year
monitoring period, and the sample result is above \1/2\ MCL, then the
next monitoring period for that sampling point is three years).
(v) If a system has a monitoring result that exceeds the MCL while
on reduced monitoring, the system must collect and analyze quarterly
samples at that sampling point until the system has results from four
consecutive quarters that are below the MCL, unless the system enters
into another schedule as part of a formal compliance agreement with the
State.
(4) Compositing: To fulfill quarterly monitoring requirements for
gross alpha particle activity, radium-226, radium-228, or uranium, 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. States will treat analytical results from the composited as the
average analytical result to determine compliance with the MCLs and the
future monitoring frequency. If the analytical result from the
composited sample is greater than \1/2\ MCL, the State may direct the
system to take additional quarterly samples before allowing the system
to sample under a reduced monitoring schedule.
(5) A gross alpha particle activity measurement may be substituted
for the required radium-226 measurement provided that the measured gross
alpha particle activity does not exceed 5 pCi/l. A gross alpha particle
activity measurement may be substituted for the required uranium
measurement provided that the measured gross alpha particle activity
does not exceed 15 pCi/l. The gross alpha measurement shall have a
confidence interval of 95% (1.65[sigma], where [sigma] is the standard
deviation of the net counting rate of the sample) for radium-226 and
uranium. When a system uses a gross alpha particle activity measurement
in lieu of a radium-226 and/or uranium measurement, the gross alpha
particle activity analytical result will be used to determine the future
monitoring frequency for radium-226 and/or uranium. If the gross alpha
particle activity result is less than detection, \1/2\ the detection
limit will be used to determine compliance and the future monitoring
frequency.
(b) Monitoring and compliance requirements for beta particle and
photon radioactivity.To determine compliance with the maximum
contaminant levels in Sec. 141.66(d) for beta particle and photon
radioactivity, a system must monitor at a frequency as follows:
(1) Community water systems (both surface and ground water)
designated by the State as vulnerable must sample for beta particle and
photon radioactivity. Systems must collect quarterly samples for beta
emitters and annual samples for tritium and strontium-90 at each entry
point to the distribution system (hereafter called a sampling point),
beginning within one quarter after being notified by the State. Systems
already designated by the State must continue to sample until the State
reviews and either reaffirms or removes the designation.
(i) If the gross beta particle activity minus the naturally
occurring potassium-40 beta particle activity at a sampling point has a
running annual average (computed quarterly) less than or equal to 50
pCi/L (screening level), the State may reduce the frequency of
monitoring at that sampling point to once every 3 years. Systems must
collect all samples required in paragraph (b)(1) of this section during
the reduced monitoring period.
(ii) For systems in the vicinity of a nuclear facility, the State
may allow the CWS to utilize environmental surveillance data collected
by the nuclear facility in lieu of monitoring at the system's entry
point(s), where the State determines if such data is applicable to a
particular water system. In the event that there is a release from a
nuclear facility, systems which are using surveillance data must begin
monitoring at the community water system's entry point(s) in accordance
with paragraph (b)(1) of this section.
(2) Community water systems (both surface and ground water)
designated by the State as utilizing waters contaminated by effluents
from nuclear facilities must sample for beta particle and photon
radioactivity. Systems must collect quarterly samples for beta emitters
and iodine-131 and annual samples for tritium and strontium-90 at each
entry point to the distribution system (hereafter called a sampling
point), beginning within one quarter after being notified by the State.
Systems already designated by the State as systems using waters
contaminated by effluents from nuclear facilities must continue to
sample until the State reviews and either reaffirms or removes the
designation.
(i) Quarterly monitoring for gross beta particle activity shall be
based on the analysis of monthly samples or the analysis of a composite
of three monthly samples. The former is recommended.
(ii) For iodine-131, a composite of five consecutive daily samples
shall be analyzed once each quarter. As ordered by the State, more
frequent monitoring shall be conducted when iodine-131 is identified in
the finished water.
[[Page 380]]
(iii) Annual monitoring for strontium-90 and tritium shall be
conducted by means of the analysis of a composite of four consecutive
quarterly samples or analysis of four quarterly samples. The latter
procedure is recommended.
(iv) If the gross beta particle activity beta minus the naturally
occurring potassium-40 beta particle activity at a sampling point has a
running annual average (computed quarterly) less than or equal to 15
pCi/L, the State may reduce the frequency of monitoring at that sampling
point to every 3 years. Systems must collect all samples required in
paragraph (b)(2) of this section during the reduced monitoring period.
(v) For systems in the vicinity of a nuclear facility, the State may
allow the CWS to utilize environmental surveillance data collected by
the nuclear facility in lieu of monitoring at the system's entry
point(s), where the State determines if such data is applicable to a
particular water system. In the event that there is a release from a
nuclear facility, systems which are using surveillance data must begin
monitoring at the community water system's entry point(s) in accordance
with paragraph (b)(2) of this section.
(3) Community water systems designated by the State to monitor for
beta particle and photon radioactivity can not apply to the State for a
waiver from the monitoring frequencies specified in paragraph (b)(1) or
(b)(2) of this section.
(4) Community water systems may analyze for naturally occurring
potassium-40 beta particle activity from the same or equivalent sample
used for the gross beta particle activity analysis. Systems are allowed
to subtract the potassium-40 beta particle activity value from the total
gross beta particle activity value to determine if the screening level
is exceeded. The potassium-40 beta particle activity must be calculated
by multiplying elemental potassium concentrations (in mg/L) by a factor
of 0.82.
(5) If the gross beta particle activity minus the naturally
occurring potassium-40 beta particle activity exceeds the screening
level, an analysis of the sample must be performed to identify the major
radioactive constituents present in the sample and the appropriate doses
must be calculated and summed to determine compliance with
Sec. 141.66(d)(1), using the formula in Sec. 141.66(d)(2). Doses must
also be calculated and combined for measured levels of tritium and
strontium to determine compliance.
(6) Systems must monitor monthly at the sampling point(s) which
exceed the maximum contaminant level in Sec. 141.66(d) beginning the
month after the exceedance occurs. Systems must continue monthly
monitoring until the system has established, by a rolling average of 3
monthly samples, that the MCL is being met. Systems who establish that
the MCL is being met must return to quarterly monitoring until they meet
the requirements set forth in paragraph (b)(1)(ii) or (b)(2)(i) of this
section.
(c) General monitoring and compliance requirements for
radionuclides.
(1) The State may require more frequent monitoring than specified in
paragraphs (a) and (b) of this section, or may require confirmation
samples at its discretion. The results of the initial and confirmation
samples will be averaged for use in compliance determinations.
(2) Each public water systems shall monitor at the time designated
by the State during each compliance period.
(3) Compliance: Compliance with Sec. 141.66 (b) through (e) will be
determined based on the analytical result(s) obtained at each sampling
point. If one sampling point is in violation of an MCL, the system is in
violation of the MCL.
(i) For systems monitoring more than once per year, compliance with
the MCL is determined by a running annual average at each sampling
point. If the average of any sampling point is greater than the MCL,
then the system is out of compliance with the MCL.
(ii) For systems monitoring more than once per year, if any sample
result will cause the running average to exceed the MCL at any sample
point, the system is out of compliance with the MCL immediately.
(iii) Systems must include all samples taken and analyzed under the
provisions of this section in determining compliance, even if that
number is greater than the minimum required.
(iv) If a system does not collect all required samples when
compliance is based on a running annual average of quarterly samples,
compliance will be based on the running average of the samples
collected.
(v) If a sample result is less than the detection limit, zero will
be used to calculate the annual average, unless a gross alpha particle
activity is being used in lieu of radium-226 and/or uranium. If the
gross alpha particle activity result is less than detection, \1/2\ the
detection limit will be used to calculate the annual average.
(4) States have the discretion to delete results of obvious sampling
or analytic errors.
(5) If the MCL for radioactivity set forth in Sec. 141.66 (b)
through (e) is exceeded, the operator of a community water system must
give notice to the State pursuant to Sec. 141.31 and to the public as
required by subpart Q of this part.