Current through Register Vol. 48, No. 38, September 20, 2024
a) Applicability. A Subpart B system supplier
that serves fewer than 10,000 persons and utilizing conventional filtration or
direct filtration must conduct continuous monitoring of turbidity for each
individual filter in a supplier's system. The following requirements apply to
continuous turbidity monitoring:
1)
Monitoring must be conducted using an approved method in Section
611.531;
2) Calibration of turbidimeters must be
conducted using procedures specified by the manufacturer;
3) Results of turbidity monitoring must be
recorded at least every 15 minutes;
4) Monthly reporting must be completed
according to Section
611.957(a);
and
5) Records must be maintained
according to Section
611.957(b).
b) Failure of Turbidity Monitoring Equipment.
If there is a failure in the continuous turbidity monitoring equipment, the
supplier must conduct grab sampling every four hours in lieu of continuous
monitoring until the turbidimeter is back on-line. The supplier has 14 days to
resume continuous monitoring before a violation is incurred.
c) Special Requirements for Systems with Two
or Fewer Filters. If a supplier's system only consists of two or fewer filters,
the supplier may conduct continuous monitoring of combined filter effluent
turbidity in lieu of individual filter effluent turbidity monitoring.
Continuous monitoring must meet the same requirements set forth in subsections
(a)(1) through (a)(4) and (b).
d)
Follow-Up Action. Follow-up action is required according to the following
requirements:
1) If the turbidity of an
individual filter (or the turbidity of combined filter effluent (CFE) for a
system with two filters that monitor CFE in lieu of individual filters) exceeds
1.0 NTU in two consecutive recordings 15 minutes apart, the supplier must
report to the Agency by the 10th of the following
month and include the filter numbers, corresponding dates, turbidity values
that exceeded 1.0 NTU, and the cause (if known) for the exceedances.
2) If a supplier was required to report to
the Agency for three months in a row and turbidity exceeded 1.0 NTU in two
consecutive recordings 15 minutes apart at the same filter (or CFE for systems
with two filters that monitor CFE in lieu of individual filters), the supplier
must conduct a self-assessment of the filters within 14 days after the day on
which the filter exceeded 1.0 NTU in two consecutive measurements for the third
straight month, unless a CPE, as specified in subsection (d)(3), was required.
A supplier that has a system with two filters that monitor CFE in lieu of
individual filters must conduct a self-assessment on both filters. The
self-assessment must consist of at least the following components: assessment
of filter performance, development of a filter profile, identification and
prioritization of factors limiting filter performance, assessment of the
applicability of corrections, and preparation of a filter self-assessment
report.
3) If a supplier was
required to report to the Agency for two months in a row and turbidity exceeded
2.0 NTU in two consecutive recordings 15 minutes apart at the same filter (or
CFE for systems with two filters that monitor CFE in lieu of individual
filters), the supplier must arrange to have a comprehensive performance
evaluation (CPE) conducted by the Agency or a third party approved by the
Agency not later than 60 days following the day the filter exceeded 2.0 NTU in
two consecutive measurements for the second straight month. If a CPE has been
completed by the Agency or a third party approved by the Agency within the 12
prior months or the system and Agency are jointly participating in an ongoing
comprehensive technical assistance (CTA) project at the system, a new CPE is
not required. If conducted, a CPE must be completed and submitted to the Agency
no later than 120 days following the day the filter exceeded 2.0 NTU in two
consecutive measurements for the second straight month.
e) Special Individual Filter Monitoring for a
Lime-Softening System. If a supplier's system utilizes lime softening, the
supplier may apply to the Agency for alternative turbidity exceedance levels
for the levels specified in subsection (d). The supplier must be able to
demonstrate to the Agency that higher turbidity levels are due to lime
carryover only, and not due to degraded filter performance.
BOARD NOTE: Derived from
40
CFR 141.560 through
141.564.
