| (ii) measure and record the turbidity level at the
effluent of each filter at least once each day the plant is in operation.
(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 must 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 fails to meet the turbidity
criteria specified in paragraph (2) of this subsection must conduct
additional monitoring.
(i) Each time a filter exceeds an applicable filtered
water turbidity level specified in paragraph (2) of this subsection
for two consecutive 15-minute readings, the public water system must
either identify the cause of the exceedance or produce a filter profile
on the filter within seven days of the exceedance.
(ii) Each time a filter exceeds the filtered turbidity
level specified in paragraph (2)(A) of this subsection for two consecutive
15-minute readings on three separate occasions during any consecutive
three-month period, the public water system must conduct a filter
assessment on the filter within 14 days of the third exceedance.
(iii) Each time the filtered water turbidity level
for a specific filter or any combination of individual filters exceeds
2.0 NTU on two consecutive 15-minute readings during two consecutive
months, the public water system must participate in a third-party
comprehensive performance evaluation (CPE). If the system serves at
least 10,000 people, the CPE must be conducted within 90 days of the
first exceedance in the second month. If the system serves fewer than
10,000 people, the CPE must be conducted within 120 days of the first
exceedance in the second month.
(iv) A public water system that uses conventional filters
may be required to participate in a special investigation conducted
by the executive director if, during two consecutive months, the public
water system fails to report individual filter effluent turbidity
levels on a day when the combined filter effluent turbidity level
exceeds 1.0 NTU.
(B) A system that serves fewer than 10,000 people,
monitors combined filter effluent turbidity in lieu of individual
filter effluent turbidity, and fails to meet the turbidity criteria
in paragraph (1)(A) of this subsection must conduct additional monitoring.
The executive director may waive these special monitoring requirements
for systems that have a corrective action schedule approved by the
executive director.
(i) Each time the combined filter effluent turbidity
level exceeds 1.0 NTU for two consecutive 15-minute readings, the
public water system must either identify the cause of the exceedance
or complete a filter profile on the combined filter effluent within
seven days of the exceedance.
(ii) Each time the combined filter effluent turbidity
level exceeds 1.0 NTU for two consecutive 15-minute readings on three
separate occasions during any consecutive three-month period, the
public water system must conduct a filter assessment on each filter
within 14 days of the third exceedance.
(iii) Each time the combined filter effluent turbidity
level exceeds 2.0 NTU on two consecutive 15-minute readings during
two consecutive months, the public water system must participate in
a third-party CPE within 120 days of the first exceedance in the second
month.
(C) A public water system may be required to participate
in a special investigation conducted by the 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.
(5) Analytical requirements for turbidity. 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 (relating to Minimum Acceptable Operating Practices
for Public Drinking Water Systems).
(A) Turbidity must be measured with turbidimeters that
use a method that conforms with the requirements as described in §290.119
of this title.
(B) A system monitoring the performance of individual
filters with on-line turbidimeters and recorders may monitor combined
filter effluent turbidity levels by either continuously monitoring
turbidity levels with an on-line turbidimeter or measuring the turbidity
level in grab samples with a bench-top turbidimeter.
(C) Continuous turbidity monitoring must be conducted
using a continuous, on-line turbidimeter and a device that records
the turbidity level reading at least once every 15 minutes.
(i) Turbidity data may be recorded electronically by
a supervisory control and data acquisition system (SCADA) or on a
strip chart. The recorder must be designed so that the operator can
accurately determine the turbidity level readings at 15-minute intervals.
(ii) If there is a failure in the continuous turbidity
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.
(iii) If the continuous turbidity monitoring equipment
at a system serving fewer than 10,000 people malfunctions, 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.
(D) A system that monitors combined filter effluent
turbidity in lieu of individual filter effluent turbidity under §290.42(d)(11)(E)(ii)
of this title must monitor the performance of individual filters using
a bench-top turbidimeter.
(E) 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.
(f) Filtration requirements for other filters. A system
that uses cartridge filters, membrane filters, or other unconventional
filtration systems to treat surface water or groundwater under the
direct influence of surface water must meet minimum filtration requirements
before the water is supplied to any consumer.
(1) Treatment technique requirements. A system that
uses unconventional filtration technologies such as membrane filters
or cartridge filters must meet treatment technique requirements prescribed
by the executive director.
(A) The filtration facilities must meet combined filter
effluent and individual filter effluent turbidity limits established
by the executive director.
(B) The filtration facilities must be operated and
maintained in accordance with requirements that the executive director
determines are needed to demonstrate the amount of Giardia and Cryptosporidium
removal achieved.
(2) Monitoring requirements. A system must monitor
the performance of its filtration facilities.
(A) A system that serves fewer than 500 people and
continuously monitors the turbidity level of each individual cartridge
or membrane unit must measure and record the turbidity level of the
combined effluent at least once each day that the plant is in operation.
(B) A system that serves at least 500 people and continuously
monitors the turbidity level of each individual cartridge or membrane
unit must measure and record the turbidity level of the combined effluent
at least every four hours that the system serves water to the public.
(C) A system using membranes must use a method approved
by the executive director to continuously monitor the quality of the
water produced by each membrane unit and record the monitoring results
at least once every five minutes. The executive director may approve
monitoring parameters other than turbidity and decrease the frequency
to once every 15 minutes if the approved operating parameters will
allow consecutive readings to be obtained between backwash or backflush
cycles.
(D) A system using membranes must conduct direct integrity
testing on each membrane unit using a procedure approved by the executive
director.
Cont'd... |
