Current through Register Vol. 48, No. 38, September 20, 2024
a)
General
1) This Section applies to CWS
suppliers that use only ground water (except ground water under the direct
influence of surface water, as defined in Section
611.102
) and which serve 1,000 or fewer people.
2) Following any total coliform-positive
sample taken under the provisions of this Section, the supplier must comply
with the repeat monitoring requirements and E. coli analytical requirements in
Section
611.1058.
3) Once all monitoring required by this
Section and Section
611.1058
for a calendar month has been completed, the supplier must determine whether
any coliform treatment technique triggers specified in Section
611.1059
have been exceeded. If any trigger has been exceeded, the supplier must
complete assessments as required by Section 611.1059.
b) Monitoring Frequency for Total Coliforms.
The monitoring frequency for total coliforms is one sample per month, except as
provided for under subsections (c) through (f).
c) Transition to Subpart AA. The Agency must
perform a special monitoring evaluation during each sanitary survey to review
the status of the supplier's system, including the distribution system, to
determine whether the system is on an appropriate monitoring schedule. After
the Agency has performed the special monitoring evaluation during each sanitary
survey, the Agency may, by a SEP issued under Section
611.110,
modify the supplier's monitoring schedule, as necessary. Alternatively, the
Agency may allow the supplier to stay on its existing monitoring schedule,
consistent with the provisions of this Section. The Agency may not allow a
supplier to begin less frequent monitoring under the special monitoring
evaluation unless the supplier has already met the applicable criteria for less
frequent monitoring in this Section.
d) Criteria for Reduced Monitoring
1) The Agency may, by a SEP, reduce the
monitoring frequency from monthly monitoring to no less than quarterly
monitoring if the supplier is in compliance with Agency-certified operator
provisions and demonstrates that it meets the criteria in subsections (d)(1)(A)
through (d)(1)(C). A supplier that loses its certified operator must return to
monthly monitoring the month following that loss.
A) The supplier has a clean compliance
history for a minimum of 12 months.
B) The most recent sanitary survey shows the
supplier is free of sanitary defects (or has an approved plan and schedule to
correct them and is in compliance with the plan and the schedule), has a
protected water source, and meets Agency-approved construction
standards.
C) The supplier meets at
least one of the following criteria:
i) An
annual site visit by the Agency that is equivalent to a Level 2 assessment or
an annual Level 2 assessment by a party approved by the Agency and correction
of all identified sanitary defects (or an approved plan and schedule to correct
them and is in compliance with the plan and schedule).
ii) Cross connection control, as approved by
the Agency.
iii) Continuous
disinfection entering the distribution system and a residual in the
distribution system in accordance with criteria specified by the
Agency.
iv) Demonstration of
maintenance of at least a 4-log removal or inactivation of viruses as provided
for under Section
611.803(b)(3).
v) Other equivalent enhancements to water
system barriers as approved by the Agency.
2) This subsection (d)(2) corresponds with
40
CFR 141.855(d)(2), which
USEPA has marked "reserved". This statement maintains structural consistency
with the corresponding federal provision.
e) Return to Routine Monthly Monitoring
Requirements. A supplier on quarterly monitoring that experience any of the
events in subsections (e)(1) through (e)(4) must begin monthly monitoring the
month following the event. The supplier must continue monthly monitoring until
it meets the reduced monitoring requirements in subsection (d).
1) The supplier triggers a Level 2 assessment
or two Level 1 assessments in a rolling 12-month period.
2) The supplier has an E. coli MCL
violation.
3) The supplier has a
coliform treatment technique violation.
4) The supplier has two Subpart AA monitoring
violations in a rolling 12- month period.
f) Additional Routine Monitoring the Month
Following a Total Coliform-Positive Sample. A supplier collecting samples on a
quarterly frequency must conduct additional routine monitoring the month
following one or more total coliform-positive samples (with or without a Level
1 treatment technique trigger). A supplier must collect at least three routine
samples during the next month, except that the Agency may, by a SEP, waive this
requirement if the conditions of subsection (f)(1), (f)(2), or (f)(3) are met.
A supplier may either collect samples at regular time intervals throughout the
month or may collect all required routine samples on a single day if samples
are taken from different sites. A supplier must use the results of additional
routine samples in coliform treatment technique trigger calculations.
1) The Agency may, by a SEP, waive the
requirement to collect three routine samples the next month in which the
supplier's system provides water to the public if the Agency, or an agent
approved by the Agency, performs a site visit before the end of the next month
in which the supplier's system provides water to the public. Although a
sanitary survey need not be performed, the site visit must be sufficiently
detailed to allow the Agency to determine whether additional monitoring or any
corrective action is needed. The Agency cannot approve an employee of the
supplier to perform this site visit, even if the employee is an agent approved
by the Agency to perform sanitary surveys.
2) The Agency may, by a SEP, waive the
requirement to collect three routine samples the next month in which the
supplier's system provides water to the public if the Agency has determined why
the sample was total coliform-positive and has established that the supplier
has corrected the problem or will correct the problem before the end of the
next month in which the supplier's system serves water to the public. In this
case, the Agency must document this decision to waive the following month's
additional monitoring requirement in writing, have it approved and signed by
the supervisor of the Agency official who recommends such a decision, and make
this document available to USEPA and the public. The written documentation must
describe the specific cause of the total coliform-positive sample and what
action the supplier has taken or will take to correct this problem.
3) The Agency may not waive the requirement
to collect three additional routine samples the next month in which the
supplier's system provides water to the public solely on the grounds that all
repeat samples are total coliform-negative. If the Agency determines that the
supplier has corrected the contamination problem before the supplier takes the
set of repeat samples required in Section 611.1058, and all repeat samples were
total coliform-negative, the Agency may, by a SEP, waive the requirement for
additional routine monitoring the next month.
BOARD NOTE: Derived from
40
CFR 141.855.
