| (i) Direct integrity tests must be conducted in a manner
that will detect a membrane defect of 3 microns or smaller and demonstrates
a removal efficiency equal to or greater than the removal credit awarded
to the membrane filtration process by the executive director.
(ii) Direct integrity test method must calculate the
log removal value for a 3-micron size particle and establish an upper
control limit which assures that the unit is capable of meeting the
removal credit approved by the executive director.
(iii) A system that has been assigned a Bin 1 classification
under the provisions of subsection (c)(3)(B) of this section must
conduct direct integrity tests at least once every seven days. The
executive director may reduce the testing requirements for other membrane
units.
(iv) A system that has been assigned a Bin 2, 3, or
4 classification under the provisions of subsection (c)(3)(B) of this
section must conduct direct integrity tests at least once each day
that the membrane unit is used for filtration. The executive director
may approve less frequent testing, based on demonstrated process reliability,
the use of multiple barriers effective for Cryptosporidium
removal or inactivation, or reliable process safeguards.
(v) A system must immediately conduct a direct integrity
test on any membrane unit that produces filtered water with turbidity
level above 0.15 NTU on two consecutive readings. The executive director
must establish alternate site-specific control limits for systems
that use other approved technology in lieu of turbidimeters to continuously
monitor the performance of membrane units.
(vi) A system must immediately remove any membrane
unit that fails a direct integrity test from service until the membrane
modules in that unit are inspected and, if necessary, repaired. A
membrane unit that has been removed from service may not be returned
to service until it has passed a direct integrity test.
(E) A system that uses cartridge filters must continuously
monitor the performance of the filtration process in a manner approved
by the executive director.
(3) Analytical requirements. All monitoring required
by this subsection must be conducted by a facility approved by the
executive director and using methods that conform to the requirements
of §290.119 of this title. Equipment used for compliance measurements
must be maintained and calibrated in accordance with §290.46(s)
of this title.
(A) Turbidity of the combined effluent must be measured
with turbidimeters that meet the requirements of subsection (e)(5)(A)
of this section.
(B) The turbidity of the water produced by each membrane
unit must be measured using the Hach FilterTrak Method 10133. The
executive director may approve the use of alternative technology to
monitor the quality of the water produced by each membrane unit.
(C) A system continuously monitoring the performance
of individual cartridges or membrane units may monitor combined effluent
turbidity levels by either continuously monitoring turbidity levels
with an on-line turbidimeter, or by measuring the turbidity level
in grab samples with a bench-top turbidimeter.
(D) Data collected from on-line instruments may be
recorded electronically by a SCADA system or on a strip chart recorder.
The recorder must be designed so that the operator can accurately
determine the value of readings at the monitoring interval approved
by the executive director.
(i) If there is a failure in the continuous monitoring
equipment at a system serving 10,000 people or more, the system must
conduct grab sampling every four hours in lieu of continuous monitoring,
but for no more than five working days following the failure of the
equipment.
(ii) If there is a failure in the continuous monitoring
equipment at a system serving fewer than 10,000 people, the system
must conduct grab sampling every four hours in lieu of continuous
monitoring, but for no more than 14 working days following the failure
of the equipment.
(E) A system that uses cartridge filters and does not
continuously monitor the turbidity of each filter unit must monitor
the performance of individual filters at least once each day using
a bench-top turbidimeter.
(F) Combined filter effluent and individual filter
effluent turbidity monitoring equipment and all associated data recording
devices shall read and record turbidity levels to adequately determine
compliance with the requirements as described in this subchapter.
The turbidity equipment and all associated recording devices shall
read and record levels:
(i) at least 10% higher than the turbidity level needed
to determine compliance with the highest applicable regulatory requirement
as described in this subchapter;
(ii) at the lowest method detection limit of the approved
turbidimeter; and
(iii) at the precision and accuracy necessary to determine
compliance with the requirements as described in this subchapter.
(4) Special investigation requirements. A system which
fails to produce water with acceptable turbidity levels, or if the
level of removal/inactivation of pathogens is inadequate or cannot
be determined, the system shall investigate the cause of the problem
and take appropriate corrective action. The executive director can
waive these special monitoring requirements for systems that have
a corrective action schedule approved by the executive director.
(A) A public water system that utilizes membrane filters
for pathogen removal may be required to participate in a special investigation
conducted by the executive director if, during two consecutive months,
the system fails to report all required direct integrity test results
for a specific membrane unit.
(B) A public water system that utilizes membrane filters
for pathogen removal may be required to participate in a special investigation
conducted by the executive director if, during two consecutive months,
a specific membrane unit fails at least one direct integrity test
and continues to produce water.
(C) A public water system may be required to participate
in a special investigation conducted by executive director when documentation
or lack of documentation from a public water system indicates that
the pathogen removal/inactivation levels are inadequate or cannot
be determined.
(g) Other treatment credits for systems in Bins 2 through
4. The executive director may grant additional pathogen removal and
inactivation credit to systems that meet enhanced design, operational,
maintenance, and reporting requirements.
(1) Individual filter effluent. The executive director
may approve an additional 1.0-log removal credit for Giardia and Cryptosporidium
to a treatment plant that uses conventional granular media
filters.
(A) The executive director will approve the additional
credit for a plant if:
(i) the system continuously monitored the filtered
water turbidity at the effluent of each individual filter and recorded
the turbidity value every 15 minutes that the filter was sending water
to the clearwell;
(ii) the turbidity level at each individual filter
effluent is less than or equal to 0.15 NTU in at least 95% of the
measurements recorded during the month; and
(iii) no individual filter produced water with turbidity
level above 0.3 NTU in two consecutive 15-minute readings.
(B) The executive director may also approve the additional
credit for a plant that does not meet the requirements of subparagraph
(A) of this paragraph if:
(i) the executive director determines that the failure
to meet the requirements of subparagraph (A) of this paragraph could
not have been prevented through optimizing plant operations, design,
or maintenance; and
(ii) the system has experienced no more than two such
failures within the most recent 12 months.
(2) Combined filter effluent. The executive director
may approve an additional 0.5-log removal credit for Cryptosporidium to a treatment plant that
uses conventional granular media filters if:
(A) the system continuously monitored the filtered
water turbidity at the effluent of each individual filter and recorded
the turbidity value every 15 minutes that the filter was sending water
to the clearwell;
(B) the turbidity level at the combined filter effluent
is less than or equal to 0.15 NTU in at least 95% of the measurements
recorded during the month; and
(C) the plant does not receive additional treatment
credit under paragraph (1) of this subsection.
(3) Second stage filtration. The executive director
will approve an additional 0.5-log removal credit for Giardia and Cryptosporidium
to a treatment plant that uses a second, separate stage of
conventional granular media filters if:
(A) the filters in both stages meet minimum design
criteria approved by the executive director;
Cont'd... |
