| (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
(III) the public water system's sample siting plan
remains representative of water quality in the distribution system.
If a required repeat sample is used to meet both requirements and
found to be E. coli -positive, the
public water system will have achieved an E.
coli MCL as defined in subsection (b)(1)(A) - (D) of this section
and corrective action will be required for the groundwater source
where the sample was found to be E. coli -positive.
(iv) If the executive director does not require corrective
action under §290.116 of this title (relating to Groundwater
Corrective Actions and Treatment Techniques) for a fecal indicator
positive source water sample collected under this subparagraph that
is not invalidated under subsection (e) of this section, the public
water system shall collect five additional source water samples from
the same source within 24 hours of being notified of the fecal indicator
positive sample.
(v) If a public water system takes more than one repeat
sample at the monitoring location required for triggered source water
monitoring, the public water system may reduce the number of additional
source water samples required under clause (iv) of this subparagraph
by the number of repeat samples taken at that location that were not E. coli- positive.
(C) Consecutive and wholesale systems. Consecutive
groundwater systems receiving drinking water from a wholesaler must
notify the wholesale system(s) within 24 hours of being notified of
the positive coliform distribution sample. The wholesale groundwater
system(s) must comply with the following:
(i) A wholesale groundwater system that receives notice
of a distribution coliform sample positive from a consecutive system
it serves must collect a sample from each of its groundwater sources
within 24 hours of the notification and analyze each sample for the
presence of E. coli (or other approved
fecal indicator).
(ii) If any raw source sample is
E. coli (or other approved fecal indicator) positive, the wholesale
groundwater system must notify all consecutive systems served by that
groundwater source of the fecal indicator positive within 24 hours
of being notified. The wholesale system and all consecutive systems
served by that groundwater source must notify their water system customers
in accordance with subsection (h)(2) of this section and shall meet
the requirements of subparagraph (B)(iv) of this paragraph.
(iii) If any raw source sample is E. coli positive, the wholesale groundwater
system shall notify all consecutive systems served by that groundwater
source of the fecal indicator source water positive within 24 hours
of being notified and shall meet the requirements of subparagraph
(B)(iv) of this paragraph.
(D) Exceptions to the triggered source monitoring requirements.
A groundwater system is not required to comply with the triggered
source monitoring requirements if any of the following conditions
exist.
(i) The executive director determines and documents
in writing, that the distribution coliform-positive sample is caused
by a distribution system deficiency; or
(ii) The distribution coliform-positive sample is collected
at a location that meets the distribution coliform sample invalidation
criteria as specified in subsection (e)(1) of this section and the
replacement sample is negative for coliforms.
(E) Assessment source monitoring. The executive director
may require monthly source assessment raw monitoring without the presence
of a positive total coliform distribution sample if well conditions
exist that indicate the groundwater may be susceptible to fecal contamination.
The executive director may conduct a hydrogeological sensitivity assessment
to determine if the source is susceptible to fecal contamination.
If requested by the executive director, groundwater systems must provide
the executive director with any existing information that will enable
the executive director to perform a hydrogeological sensitivity assessment.
A groundwater system conducting assessment source monitoring may use
a triggered source sample collected under subparagraph (A) of this
paragraph to meet the assessment source monitoring requirement. A
groundwater system with a groundwater source sample collected under
this subparagraph or under subparagraph (A) of this paragraph that
is fecal indicator positive and that is not invalidated under subsection
(e)(2) of this section, including consecutive systems served by the
groundwater source, shall conduct public notification under §290.122(a)
of this title (relating to Public Notification). Additionally, an
assessment source monitoring sample may be used as a triggered source
monitoring sample if collected within 24 hours of notification of
the coliform-positive distribution sample. Cont'd... |
