| (iii) The effluent line of each filter installed after
January 1, 1996, must be equipped with a slow opening valve or another
means of automatically preventing flow surges when the filter begins
operation.
(E) The filters shall be provided with facilities to
monitor the performance of the filter. Monitoring devices shall be
designed to provide the ability to measure and record turbidity as
required by §290.111 of this title.
(i) Each filter shall be equipped with a sampling tap
so that the effluent turbidity of the filter can be individually monitored.
(ii) Each filter operated by a public water system
that serves fewer than 10,000 people shall be equipped with an on-line
turbidimeter and recorder which will allow the operator to measure
and record the turbidity at 15-minute intervals. The executive director
may allow combined filter effluent monitoring in lieu of individual
filter effluent monitoring under the following conditions:
(I) The public water system has only two filters that
were installed prior to October 1, 2000, and were never equipped with
individual on-line turbidimeters and recorders; and
(II) The plant is equipped with an on-line turbidimeter
and recorder which will allow the operator to measure and record the
turbidity level of the combined filter effluent at a location prior
to clearwell storage at 15-minute intervals.
(iii) Each filter operated by a public water system
that serves at least 10,000 people shall be equipped with an on-line
turbidimeter and recorder which will allow the operator to measure
and record the turbidity at 15-minute intervals.
(iv) Each filter installed after October 1, 2000, shall
be equipped with an on-line turbidimeter and recorder which will allow
the operator to determine the turbidity at 15-minute intervals.
(v) Each filter unit that is not equipped with an on-line
turbidimeter and recorder shall be equipped with a device to indicate
loss of head through the filter. In lieu of loss-of-head indicators,
declining rate filter units may be equipped with rate-of-flow indicators.
(F) Filters shall be designed to ensure adequate cleaning
during the backwash cycle.
(i) Only filtered water shall be used to backwash the
filters. This water may be supplied by elevated wash water tanks,
by the effluent of other filters, or by pumps which take suction from
the clearwell and are provided for backwashing filters only. For installations
having a treatment capacity no greater than 150,000 gallons per day,
water for backwashing may be secured directly from the distribution
system if proper controls and rate-of-flow limiters are provided.
(ii) The rate of filter backwashing shall be regulated
by a rate-of-flow controller or flow control valve.
(iii) The rate of flow of backwash water shall not
be less than 20 inches vertical rise per minute (12.5 gpm/sq ft) and
usually not more than 35 inches vertical rise per minute (21.8 gpm/sq
ft).
(iv) The backwash facilities shall be capable of expanding
the filtering bed during the backwash cycle.
(I) For facilities equipped with air scour, the backwash
facilities shall be capable of expanding the filtering bed at least
15% during the backwash cycle.
(II) For mixed-media filters without air scour, the
backwash facilities shall be capable of expanding the filtering bed
at least 25% during the backwash cycle.
(III) For mono-media sand filters without air scour,
the backwash facilities shall be capable of expanding the filtering
bed at least 40% during the backwash cycle.
(v) The filter freeboard in inches shall exceed the
wash rate in inches of vertical rise per minute.
(vi) When used, surface filter wash systems shall be
installed with an atmospheric vacuum breaker or a reduced pressure
principle backflow assembly in the supply line. If an atmospheric
vacuum breaker is used, it shall be installed in a section of the
supply line through which all the water passes and which is located
above the overflow level of the filter.
(vii) Gravity filters installed after January 1, 1996,
shall be equipped with air scour backwash or surface wash facilities.
(G) Each filter installed after October 1, 2000, shall
be equipped with facilities that allow the filter to be completely
drained without removing other filters from service.
(12) Pipe galleries shall provide ample working room,
good lighting, and good drainage provided by sloping floors, gutters,
and sumps. Adequate ventilation to prevent condensation and to provide
humidity control is also required.
(13) The identification of influent, effluent, waste
backwash, and chemical feed lines shall be accomplished by the use
of labels or various colors of paint. Where labels are used, they
shall be placed along the pipe at no greater than five-foot intervals.
Color coding must be by solid color or banding. If bands are used,
they shall be placed along the pipe at no greater than five-foot intervals.
(A) A plant that is built or repainted after October
1, 2000, must use the following color code. The color code to be used
in labeling pipes is as follows:
Attached Graphic
(B) A plant that was repainted before October 1, 2000,
may use an alternate color code. The alternate color code must provide
clear visual distinction between process streams.
(C) The system must maintain clear, current documentation
of its color code in a location easily accessed by all personnel.
(14) All surface water treatment plants shall provide
sampling taps for raw, settled, individual filter effluent, and clearwell
discharge. Additional sampling taps shall be provided as appropriate
to monitor specific treatment processes.
(15) An adequately equipped laboratory shall be available
locally so that daily microbiological and chemical tests can be conducted.
(A) For plants serving 25,000 persons or more, the
local laboratory used to conduct the required daily microbiological
analyses must be accredited by the executive director to conduct coliform
analyses.
(B) For plants serving populations of less than 25,000,
the facilities for making microbiological tests may be omitted if
the required microbiological samples can be submitted to a laboratory
accredited by the executive director on a timely basis.
(C) All surface water treatment plants shall be provided
with equipment for making at least the following determinations:
(i) pH;
(ii) temperature;
(iii) disinfectant residual;
(iv) alkalinity;
(v) turbidity;
(vi) jar tests for determining the optimum coagulant
dose; and
(vii) other tests deemed necessary to monitor specific
water quality problems or to evaluate specific water treatment processes.
(D) Each surface water treatment plant that uses chlorine
dioxide shall provide testing equipment for measuring chlorine dioxide
and chlorite levels.
(E) Each surface water treatment plant that uses sludge-blanket
clarifiers shall be equipped with facilities to monitor the depth
of the sludge blanket.
(F) Each surface water treatment plant that uses solids-recirculation
clarifiers shall be equipped with facilities to monitor the solids
concentration in the slurry.
(16) Each surface water treatment plant shall be provided
with a computer and software for recording performance data, maintaining
records, and submitting reports to the executive director. The executive
director may allow a water system to locate the computer at a site
other than the water treatment plant only if performance data can
be reliably transmitted to the remote location on a real-time basis,
the plant operator has access to the computer at all times, and performance
data is readily accessible to agency staff during routine and special
investigations.
(17) Reverse osmosis and nanofiltration membrane systems
not provided for microbiological quality control shall conform to
the requirements of subsection (b)(9) of this section.
(e) Disinfection.
(1) All water obtained from surface sources or groundwater
sources that are under the direct influence of surface water must
be disinfected in a manner consistent with the requirements of §290.110
of this title.
(2) All groundwater must be disinfected prior to distribution
and in a manner consistent with the requirements of §290.110
of this title. The point of application must be ahead of the water
storage tank(s) if storage is provided prior to distribution. Permission
to use alternate disinfectant application points must be obtained
in writing from the executive director.
(3) Disinfection equipment shall be selected and installed
so that continuous and effective disinfection can be secured under
all conditions.
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