R309-520-7. Chlorine

  (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 mixing. 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 releases 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 water as 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 Requirements 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.