(1) General Requirements for all Chlorination
Installations.
(a) Chemical Types.
Disinfection by chlorination shall be accomplished by gaseous
chlorine or hypochlorite solutions. Hypochlorite solutions can be purchased,
generated on site, or prepared by dissolving solids.
(b) Feed Equipment.
Solution-feed gas type chlorinators, direct-feed gas type
chlorinators or hypochlorite liquid feeders of a positive displacement type
shall be provided. Solution-feed gas type chlorinators are preferred. Use
caution when selecting direct-feed gas type chlorinators.
(c) Chlorine Feed Capacity.
(i) The capacity of the chlorine feed
equipment shall be sized to provide at least 2 mg/L during peak
demand.
(ii) The feed equipment
shall operate accurately over the design feeding range.
(iii) The feed equipment shall be designed to
maintain a detectable residual at all times, at all points within the intended
area in the distribution system.
(d) Automatic Proportioning.
Automatic proportioning chlorinators shall be required where
the rate of flow of the water to be treated or chlorine demand of the water to
be treated is not reasonably constant.
(e) Injector, Eductor, or Diffuser.
(i) Chlorine shall be added at a point that
allows rapid and thorough mix ing. The center of a pipeline is the preferred
application point.
(ii) The
selection of equipment shall consider the point of application, the quantity of
chlorine to be added, the size and flow of the chlorine solution line, the back
pressure of the to-be-treated water flow, and the equipment operating
pressure.
(iii) A suitable strainer
to prevent small debris from clogging chlorine feed equipment shall be
provided. Provision for flushing the strainer is required.
(f) Point of Application for Surface Water.
The design of plants treating surface water or ground water
under the direct influence of surface water shall make provisions to add
chlorine at various process points as needed.
(g) Minimization of Chlorinated Overflow.
The design shall minimize the release of chlorinated water
into the environment, for example, the discharge of chlorinated water from tank
overflows. Such release s must comply with rules of Division of Water Quality
that pertain to discharge of pollution.
(h) Prevention of Cross Connections.
(i) The design shall prevent contamination of
the treated water supply by make-up water of lesser quality.
(ii) All chlorine solution make-up water
shall be at least of equal quality to the water receiving the chlorine
solution. At surface water treatment facilities, pre-chlorination and
post-chlorination processes shall be independent to prevent cross connections
where pre-chlorination make-up water is not finished water.
(i) Flow Measurement.
The design of the chlorination system shall provide a means
to measure the flow rate of treated wateras a basis for dosing.
(j) Residual Testing Equipment.
The water system shall have chlorine residual test equipment
capable of measuring residuals to the nearest 0.1 mg/L in the range below 0.5
mg/L, to the nearest 0.3 mg/L between 0.5 mg/L and 1.0 mg/L and to the nearest
0.5 mg/L above 1.0 mg/L.
(k) Standby and Backup Equipment.
(i) A spare parts kit shall be provided and
maintained for all chlorinators to repair parts subject to wear and breakage.
If there could be a large difference in feed rates between routine and
emergency dosages, multiple gas metering tubes shall be provided, at least one
for each dose range, to assure accurate control of the chlorine feed under both
routine and emergency conditions.
(ii) Where chlorination is required for
disinfection of a water supply, standby equipment of sufficient capacity shall
be available to replace the largest unit in the event of its failure.
(iii) Standby power shall be available,
during power outages, for operation of chlorinators where disinfection of the
water supply is required unless operation of the chlorinator does not require
power.
(l) Heating,
Lighting, Ventilation.
Chlorinator buildings shall be heated, lighted and ventilated
as necessary to assure proper operation of the equipment and safety of the
operators.
(m) Incompatible
Chemicals.
The design shall ensure that incompatible chemicals that may
damage or deteriorate chlorination facilities are stored separately from
chlorination equipment and chemicals.
(2) Additional Requirement s for Gas
Chlorinators.
(a) Automatic Switch over.
Automatic Switch over of chlorine cylinders shall be provided
if continuous disinfection is required.
(b) Gas Scrubbers.
One-ton chlorine cylinder operating areas shall be equipped
with a gas scrubber per the International Fire Code capable of treating the
release of chlorine gas from the largest single cylinder at its maximum flow
rate. Furthermore, local toxic gas ordinances shall be complied with if they
exist.
(c) Heat.
The design of the chlorination room shall assure that the
temperature in the room will not fall below 32 degrees F or the temperature
required for proper operation of the chlorinator, whichever is greater.
(d) Ventilation.
(i) Chlorination equipment rooms which
contain chlorine cylinders, tanks, equipment and gaseous chlorine lines under
pressure shall have at least one exhaust fan.
(ii) Chlorine room exhaust fan(s), when
operating, shall provide at least one complete room air change per
minute.
(iii) Chlorine room exhaust
fan(s) shall take suction inside the chlorine room near the floor, as far as
practical from the door and air inlet, and discharge air outside of the
building away from air inlets.
(iv)
Chlorine room air inlets shall be through wall louvers near the
ceiling.
(v) Separate switches for
the chlorine room fans and lights shall be located near the entrance to the
room and shall be protected from vandalism . The switches shall be located
outside the chlorine room if housed in a water treatment plant.
(vi) The ventilation system for one-ton
chlorine cylinder operating areas shall be designed to operate independently
from the ventilation system for the rest of the treatment plant. One-ton
chlorine cylinder operating areas shall be designed to maintain negative
pressure per the International Fire Code.
(e) Chlorine Vent Line.
The chlorine vent line shall discharge outside, above grade,
at a point least susceptible to vandalism, and shall have the end covered with
a No. 14 mesh non-corrodible screen.
(f) Housing.
(i) Housing shall be provided for
chlorination equipment and storage to ensure proper function and
security.
(ii) Chlorine cylinders
shall not be stored in direct sunlight or exposed to excessive heat.
(g) Housing at Water Treatment
Plants.
A separate chlorine room, for chlorine cylinders and feed
equipment, shall be provided at all water treatment plants with multiple
processes and operating areas.
(i) The
chlorine room shall have shatter resistant inspection window(s) installed in an
interior wall preferably located so that an operator may read the weighing
scales without entering the chlorine room.
(ii) All openings between the chlorine room
and the remainder of the plant shall be sealed.
(iii) Outward-opening doors shall be equipped
with panic bars to allow rapid exit.
(iv) Floor drains are discouraged but, where
provided, shall discharge to the outside of the building and shall not be
connected to other internal or external drain systems.
(v) Chlorine feed lines shall not carry
pressurized chlorine gas beyond the chlorine room. Only vacuum lines may be
routed to other portions of the building outside the chlorine room. Any
openings for these lines must be adequately sealed.
(vi) The design of operating areas for
one-ton cylinders shall allow full and empty cylinders to be stored in separate
areas.
(h) Cylinder
Security.
Chlorine cylinders shall be restrained in position to prevent
upset.
(i) Weighing
Scales.
Scales shall be provided for determining chlorine cylinder
weight. Scales should be of a corrosion resistant material and should be placed
in a location remote from any moisture. Scales shall be accurate enough to
indicate loss of weight to the nearest one pound for 150 pound cylinders and to
the nearest 10 pounds for one ton cylinders.
(j) Pressure Gauges.
Pressure gauges shall be provided on the inlet and outlet of
each chlorine eductor.
(k)
Gas Masks.
(i) Where chlorine gas in one-ton
cylinders is handled, respiratory protection equipment, meeting the
requirements of the National Institute for Occupational Safety and Health
(NIOSH) shall be available and shall be stored at a convenient location, but
not inside any room where chlorine is used or stored. The units shall use
compressed air, have at least a 30 minute capacity, and be compatible with
units used by the fire department responsible for the plant.
(ii) Where 150 pound chlorine cylinders are
used, a respirator recommended by the National Institute for Occupational
Safety and Health must be available.
(l) Chlorine Leak Detection and Repair.
(i) A bottle of Ammonium Hydroxide, 56%
ammonia solution, shall be available for chlorine leak detection.
(ii) Where one-ton cylinders are used, a leak
repair kit approved by the Chlorine Institute shall be provided.
(iii) Continuous chlorine leak detection
equipment is required for one-ton cylinders.
(iv) Where a continuous leak detector is
provided, it shall be equipped with both an audible alarm and a warning light
to ensure operator safety.
(3) Additional Requirements for Hypochlorite
Systems.
(a) General Requirements.
(i) Emergency Eyewash and Safety Showers.
Emergency eyewash stations and safety showers shall be
provided at all hypochlorite installations where concentrated hypochlorite
solutions, containing 5% or greater available chlorine by volume, are handled
in containers greater than 55 gallons. Where hypochlorite solutions are used at
remote locations or in quantities of 55 gallons or less on site, safety showers
are not required and alternative emergency eyewash may be provided.
(ii) Storage of Liquid
Hypochlorite to Prevent Decay.
Storage and injection areas shall be designed to minimize the
decay in strength of concentrated hypochlorite solutions from excessive heat or
direct sunlight.
(iii) Feed
Equipment - Chemical Addition.
Hypochlorite feed equipment shall generally conform with
R309-525-11,
Chemical Addition.
(iv)
Feed Equipment - Certification.
The hypochlorite feed equipment for drinking water treatment
shall be certified to meet ANSI/NSF Standard 61.
(b) Concentrated Hypochlorite Solutions.
The water system shall provide an operational means to avoid
the injection of significantly decayed hypochlorite solutions, for example by
keeping records on site of the delivery date of the hypochlorite solution.
(c) On-Site Generation of
Hypochlorite Solutions.
(i) The on-site
hypochlorite generation systems used for drinking water treatment shall be
certified as meeting the NSF/ANSI Standard 61.
(ii) Manufacturer recommendations for safety
with respect to equipment and electrical power shall be followed.
(iii) The make-up water used in on-site
generation shall be of drinking water quality.
(iv) The hydrogen gas generated in the
electrolytic cell of the on-site generation system shall be vented upward to
the outside of the building in a dedicated, unobstructed line.
(d) Hypochlorite Tablets.
(i) Before selecting a hypochlorite tablet
disinfection process, water hardness, solubility of hypochlorite tablets, water
temperature, and other water quality factors shall be taken into
consideration.
(ii) The
hypochlorite dissolution equipment for drinking water treatment shall be
certified as meeting the ANSI/NSF Standard 61.
(iii) The design shall allow the hypochlorite
tablets to be stored in accordance with the manufacturer's safety guidelines
and in their original containers in a cool, dry, well-ventilated area. The
hypochlorite tablets shall not be stored near combustible materials or acids to
avoid fire or the release of toxic gases.
