| MCL violation under any of the conditions
as described in subsection (b)(1)(A) - (D) of this section or has
exceeded the coliform treatment technique triggers as described in
subsection (c)(1) and (2) of this section.
(B) The public water system must collect all repeat
samples on the same day, except a public water system with a single
service connection may collect daily repeat samples over a three-day
period until the required number of repeat samples has been collected.
(C) Unless the public water system meets the provisions
of clause (i) or (ii) of this subparagraph, the public water system
must collect at least one repeat sample from the sampling tap where
the original coliform-positive sample was taken, and at least one
repeat sample at a tap within five service connections upstream and
at least one repeat sample at a tap within five service connections
downstream of the original sampling site. If the positive routine
sample was collected at the end of the distribution system, or one
service connection away from the end of the distribution system, one
repeat sample must be collected at that point and the other two repeat
samples must be collected within five connections upstream of that
point.
(i) As approved by the executive director, public water
systems may propose repeat monitoring locations to the executive director
that the public water system considers to be representative of a pathway
for contamination of the distribution system. A public water system
may elect to specify either alternative fixed locations or criteria
for selecting repeat sampling sites on a situational basis in a written
standard operating procedure (SOP) in its Sample Siting Plan. The
public water system shall design its SOP to focus the repeat samples
at locations that best verify and determine the extent of potential
contamination of the distribution system area based on specific situations.
The executive director may modify the SOP or require alternative monitoring
locations as needed.
(ii) As approved by the executive director, groundwater
public water systems serving 1,000 or fewer people may propose repeat
sampling locations to the executive director, in a written SOP in
its Sample Siting Plan, that differentiate potential source water
and distribution system contamination (e.g., by sampling at entry
points to the distribution system). A groundwater public water system
with a single well required to conduct triggered source water monitoring
may, with written executive director approval, take one of its repeat
samples at the monitoring location required for triggered source water
monitoring under paragraph (4) and (4)(A) of this subsection if the
public water system demonstrates to the executive director that the
Sample Siting Plan remains representative of water quality in the
distribution system. If approved by the executive director, the public
water system may use that sample result to meet the monitoring requirements
for both repeat monitoring under this paragraph and triggered source
monitoring under paragraph (4) and (4)(A) of this subsection.
(iii) All public water systems shall include all sample
sites as required by this subparagraph and any required SOPs for any
proposed sampling sites as described in clauses (i) and (ii) of this
subparagraph in the public water system's Sample Siting Plan in accordance
with paragraph (6) of this subsection.
(D) If one or more repeat samples in the set is total
coliform-positive, the public water system must collect an additional
set of repeat samples in the manner specified in subparagraphs (A)
- (C) of this paragraph. The additional samples must be collected
within 24 hours of the public water system being notified of the positive
result or as soon as possible if the local laboratory is closed. The
executive director may extend the 24-hour limit on a case-by-case
basis if the public water system has a logistical problem in collecting
the repeat samples within 24 hours that is beyond the public water
system's control. In accordance with 40 Code of Federal Regulations
(CFR) §141.858(a)(1) the executive director is prohibited from
waiving the requirement for a public water system to collect repeat
samples as specified in subparagraphs (A) - (D) of this paragraph.
The public water system must repeat this process until either one
of the following occurs:
(i) total coliforms are not detected in one complete
set of repeat samples;
(ii) a coliform treatment technique trigger as described
in subsection (c)(1) and (2) of this section has been exceeded; or
(iii) If a treatment technique trigger as described
in subsection (c)(1) and (2) of this section is exceeded as a result
of a routine sample being total coliform-positive, public water systems
are required to conduct only one round of repeat monitoring for each
total coliform-positive routine sample.
(E) After a public water system collects a routine
sample and before it learns the results of the analysis of that sample,
if it collects another routine sample(s) from within five adjacent
service connections of the initial sample, and the initial sample
is found to contain total coliform bacteria, then the public water
system may count the subsequent sample(s) as a repeat sample instead
of as a routine sample.
(F) A total coliform-positive sample invalidated under
this subsection does not count towards meeting the minimum repeat
monitoring requirements of this subsection. Unless the executive director
has invalidated the sample in accordance with subsection (e) of this
section, all repeat coliform sample results must be used to determine
compliance with subsection (b)(1) of this section and to determine
treatment technique trigger and assessment requirements as described
in subsection (c)(1) and (2) of this section.
(4) General requirements for raw groundwater source
monitoring. Groundwater systems must comply, unless otherwise noted,
with the requirements of this section. Any raw groundwater source
sample required under this paragraph must be collected at a location
prior to any treatment of the groundwater source and use analytical
procedures and methods described in §290.119(b)(10) of this title
(relating to Analytical Procedures). The public water system may collect
a sample at an executive director-approved location prior to any treatment
to meet the requirements of this paragraph and subparagraph (A) of
this paragraph if the sample is representative of the water quality
of that well.
(A) Triggered source monitoring general requirements.
A groundwater system must conduct triggered source water monitoring
for E. coli (or other approved fecal
indicator), if both of the following conditions exist.
(i) The system does not provide at least 4-log treatment
of viruses (as defined in §290.103(44) of this title (relating
to Definitions)) before the first customer for each groundwater source;
and
(ii) The system is notified that a routine distribution
coliform sample is positive and the sample is not invalidated under
subsection (e)(1) of this section.
(B) Triggered source monitoring sampling requirements.
A groundwater system must collect, within 24 hours of notification
of the routine distribution total coliform-positive sample, at least
one raw groundwater source E. coli (or
other approved fecal indicator) sample from each groundwater source
in use at the time the distribution coliform-positive sample was collected.
(i) The executive director may extend the 24-hour time
limit on a case-by-case basis if the system cannot collect the raw
groundwater source sample within 24 hours due to circumstances beyond
its control. If the executive director extends the 24-hour time limit
on a case-by-case basis, the public water system must collect the
sample within 48 hours.
(ii) If approved by the executive director and documented
in the public water system's monitoring plan, public water systems
with more than one groundwater source may be allowed to sample a representative
groundwater source or sources. Public water systems shall modify their
current monitoring plan to identify one or more groundwater sources
that are representative of each distribution coliform sampling site
and is intended to be used for representative source sampling.
(iii) A groundwater system with one well serving 1,000
people or fewer may use one of the three required repeat samples collected
from a raw groundwater source to meet both the repeat requirements
of paragraph (3) of this subsection and the triggered raw source monitoring
requirements in this paragraph when all of the following requirements
are met:
(I) the fecal indicator used is E.
coli;
(II) the executive director has provided written approval
for the public water system to meet the monitoring requirements for
both repeat monitoring under paragraph (3) of this subsection and
triggered source monitoring under this paragraph and subparagraph
(A) of this paragraph; and
Cont'd... |
