| (i) If any of the SOC contaminants listed in subsection
(b)(1) of this section are detected in a composite sample, then a
follow-up sample must be taken from each entry point to the distribution
system included in the composite and analyzed within 14 days of collection.
(ii) If duplicates of the original SOC sample taken
from each entry point to the distribution system used in the composite
are available, the executive director may use these duplicates instead
of resampling. The duplicate must be analyzed within 14 days of collection
and the results reported to the executive director.
(iii) Compositing may only be permitted at entry points
to the distribution system within a single system.
(2) VOC monitoring requirements. Monitoring of the
VOC contaminants shall be conducted at the frequency and locations
given in this paragraph.
(A) VOC monitoring locations. Monitoring of the VOC
contaminants shall be conducted at the following locations.
(i) Systems shall routinely sample at sample sites
representative of each entry point to the distribution system.
(ii) Subsequent samples must be taken at the same sample
site unless the executive director determines that a change in conditions
makes a different sample site more representative of the water available
to customers.
(iii) The executive director must approve any change
in sampling location.
(B) Initial VOC monitoring frequency. Prior to using
water as a drinking water source, public water systems shall monitor
at the frequency established by the executive director to ensure that
the water distributed to customers will comply with the MCLs for VOCs.
(C) Routine VOC monitoring frequency. Monitoring of
the VOC contaminants shall be conducted at the following frequency.
(i) Community and nontransient, noncommunity water
systems shall take four consecutive quarterly samples for each VOC
contaminant listed in subsection (b)(2) of this section during each
compliance period, beginning with the initial compliance period.
(ii) If the initial monitoring for VOC contaminants
has been completed, and the system did not detect any VOC contaminant
listed in subsection (b)(2) of this section, the system shall take
one sample annually beginning with the initial compliance period.
(iii) After a minimum of three years of annual sampling,
the executive director may allow groundwater systems with no previous
detection of any VOC contaminant listed in subsection (b)(2) of this
section to take one sample during each compliance period.
(iv) Each community and nontransient, noncommunity
groundwater system that does not detect a VOC contaminant listed in
subsection (b)(2) of this section may be granted a waiver from the
annual or triennial requirements of subsection (c)(2)(C)(ii) and (iii)
of this section after completing the initial monitoring. For the purposes
of this section, detection is defined as an analytical result of 0.0005
mg/L or greater. A waiver shall be effective for no more than six
years (two compliance periods).
(v) Each public water system shall monitor at the time
designated by the executive director within each compliance period.
(D) Increased VOC monitoring. The executive director
may change the monitoring frequency for VOCs.
(i) Sample sites that exceed the VOC MCLs of subsection
(b)(2) of this section, as determined by subsection (f) of this section,
must be monitored quarterly. After a minimum of four consecutive quarterly
samples that show the system is in compliance as specified in subsection
(f) of this section and after the executive director determines that
the system is reliably and consistently below the MCL, the executive
director may allow the system to monitor annually during the quarter
that previously yielded the highest analytical result.
(ii) The executive director may require a confirmation
sample for positive or negative results. If a confirmation sample
is required by the executive director, the result must be averaged
with the first sampling result and the average is used for the compliance
determination as specified by subsection (f) of this section. The
executive director has discretion to delete results of obvious sampling
errors from this calculation.
(iii) If a VOC contaminant listed in subsection (b)(2)
of this section is detected at a level exceeding 0.0005 mg/L in any
sample, then:
(I) the system must monitor quarterly at each entry
point to the distribution system that resulted in a detection;
(II) the executive director may decrease the quarterly
monitoring requirement specified in subsection (c)(2)(D)(iii)(I) of
this section provided that the executive director has determined that
the system is reliably and consistently below the MCL. In no case
shall the executive director make this determination unless a groundwater
system takes a minimum of two quarterly samples and a surface water
system takes a minimum of four quarterly samples;
(III) if the executive director determines that the
system is reliably and consistently below the MCL, the executive director
may allow the system to monitor annually. Systems that monitor annually
must monitor during the quarter that previously yielded the highest
analytical result;
(IV) systems which have three consecutive annual samples
with no detection of a contaminant may be granted a waiver as specified
in subparagraph (E) of this paragraph; and
(V) groundwater systems that have detected one or more
of the following two-carbon organic compounds: trichloroethylene,
tetrachloroethylene, 1,2-dichloroethane, 1,1,1-trichloroethane, cis-1,2-dichloroethylene,
trans-1,2-dichloroethylene, or 1,1-dichloroethylene shall monitor
quarterly for vinyl chloride. A vinyl chloride sample shall be taken
at each entry point to the distribution system at which one or more
of the two-carbon organic compounds was detected. If the result of
the first analysis does not detect vinyl chloride, the executive director
may reduce the quarterly monitoring frequency for vinyl chloride to
one sample during each compliance period. Surface water systems are
required to monitor for vinyl chloride as specified by the executive
director.
(iv) The executive director may increase the required
VOC monitoring frequency, where necessary, to detect variations within
the system (e.g., fluctuations in concentration due to seasonal use,
changes in water source, etc.).
(E) Waivers for VOC monitoring. The executive director
may grant a waiver after evaluating the previous use (including transport,
storage, or disposal) of the contaminant within the watershed or zone
of influence of the water sources. If a determination by the executive
director reveals no previous use of the contaminant within the watershed
or zone of influence, a waiver may be granted. If previous use of
the contaminant is unknown or it has been used previously, then the
following factors shall be used to determine whether a waiver is granted:
(i) previous analytical results;
(ii) the proximity of the system to a potential point
or non-point source of contamination. Point sources include spills
and leaks of chemicals at or near a water treatment facility or at
drinking water sources manufacturing, distribution, or storage facilities,
or from hazardous and municipal waste landfills and other waste handling
or treatment facilities;
(iii) the environmental persistence and transport of
the contaminants;
(iv) the number of persons served by the public water
system and the proximity of a smaller system to a larger system;
(v) how well the water source is protected against
contamination (e.g., is it a surface or groundwater system). Groundwater
systems must consider factors such as depth of the well, the type
of soil, and well construction. Surface water systems must consider
watershed protection;
(vi) as a condition of the waiver, a groundwater system
must take one sample at each entry point to the distribution system
during the time the waiver is effective (i.e., one sample during two
compliance periods or six years) and update its vulnerability assessment
considering the factors listed in this paragraph. Based on this updated
vulnerability assessment, the executive director must reconfirm that
the system is not vulnerable. If the executive director does not make
this reconfirmation within three years of the initial determination,
then the waiver is invalid and the system is required to sample annually;
and
(vii) community and nontransient surface water systems
that do not detect a VOC contaminant listed in subsection (b)(2) of
this section may be considered by the executive director for a waiver
from the annual sampling requirements of subparagraph (C)(ii) of this
paragraph after completing the initial monitoring. Systems meeting
this criteria must be determined by the executive director to be non-vulnerable
based on a vulnerability assessment during each compliance period.
Each system receiving a waiver shall sample at the frequency specified
by the executive director (if any).
Cont'd... |
