| (4) Analytical requirements. All monitoring required
by this subsection must be conducted at a facility approved by the
executive director and using methods that conform to the requirements
of §290.119 of this title (relating to Analytical Procedures).
(A) The pH analysis must be conducted using a pH meter
with a minimum accuracy of plus or minus 0.1 pH units.
(B) The temperature of the water must be measured using
a thermometer or thermocouple with a minimum accuracy of plus or minus
0.5 degrees Celsius.
(C) The free chlorine or chloramine residual (measured
as total chlorine) must be measured to a minimum accuracy of plus
or minus 0.1 milligrams per liter (mg/L). Color comparators may be
used for distribution system samples only. When used, a color comparator
must have current reagents, an unfaded and clear color comparator,
a sample cell that is not discolored or stained, and must be properly
stored in a cool, dark location where it is not subjected to conditions
that would result in staining. The color comparator must be used in
the correct range. If a sample reads at the top of the range, the
sample must be diluted with chlorine-free water, then a reading taken
and the resulting residual calculated.
(D) The chlorine dioxide residual must be measured
to a minimum accuracy of plus or minus 0.05 mg/L using a method that
conforms to the requirements of §290.119 of this title. The DPD-glycine
method using a colorimeter or spectrophotometer may be utilized only
with the written permission of the executive director.
(E) The ozone residual must be measured to a minimum
accuracy of plus or minus 0.05 mg/L using the Indigo Method and using
a colorimeter or spectrophotometer.
(F) The UV dose must be measured by a calibrated sensor
approved by the executive director.
(e) Filtration requirements for conventional filters.
A system that uses granular media filters 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 for combined filter
effluent. Treatment plants using conventional media filtration must
meet the following turbidity requirements.
(A) The turbidity level of the combined filter effluent
must never exceed 1.0 nephelometric turbidity unit (NTU).
(B) The turbidity level of the combined filter effluent
must be 0.3 NTU or less in at least 95% of the samples tested each
month.
(2) Performance criteria for individual filter effluent.
The filtration techniques must ensure the public water system meets
the following performance criteria.
(A) The turbidity from each individual filter effluent
should never exceed 1.0 NTU.
(B) At a public water system that serves 10,000 people
or more, the turbidity from each individual filter effluent should
not exceed 0.5 NTU at four hours after the individual filter is returned
to service after backwash or shutdown.
(3) Routine turbidity 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 filter
must measure and record the turbidity level of the combined filter
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 filter must measure
and record the turbidity level of the combined filter effluent at
least every four hours that the system serves water to the public.
(C) Except as provided in subparagraph (D) of this
paragraph, a system must continuously monitor the filtered water turbidity
at the effluent of each individual filter and record the turbidity
value every 15 minutes.
(D) A system that serves fewer than 10,000 people and
monitors combined filter effluent turbidity in lieu of individual
filter effluent turbidity under the provisions of §290.42(d)(11)(E)(ii)
of this title (relating to Water Treatment) must:
(i) continuously monitor the turbidity of the combined
filter effluent and record the turbidity value every 15 minutes; and
(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.
Cont'd... |
