Current through Register Vol. XLI, No. 50, December 13, 2024
Section 64-77-7 - Chemical Application7.1. General. -- No chemicals shall be applied to treat drinking waters unless specifically approved by the BPH.7.1.a. Plans and specifications. -- Plans and specifications shall be submitted to the BPH for review and approval and shall include: descriptions of feed equipment, including maximum and minimum feed ranges; the location of feeders, piping layout and points of application; storage and handling facilities; specifications for chemicals to be used; operating and control procedures including proposed application rates; the descriptions of testing equipment and procedures; system including all tanks with capacities, (with drains, overflows, and vents), feeders, transfer pumps, connecting piping, valves, points of application, backflow prevention devices, air gaps, secondary containment and safety eye washes and showers.7.1.b. Chemical application. -- Chemicals shall be applied to the water at such points and by such means as to assure maximum efficiency of treatment, assure maximum safety to consumers, provide maximum safety to operators, assure satisfactory mixing of the chemicals with the water, provide maximum flexibility of operation through various points of application, when appropriate, and prevent backflow or back-siphonage between multiple points of feed through common manifolds.7.1.c. General equipment design. -- General equipment design shall be such that: feeders are able to supply, at all times, the necessary amounts of chemicals at an accurate rate, throughout the range of feed; chemical-contact materials and surfaces are resistant to the aggressiveness of the chemical solution; corrosive chemicals are introduced in such a manner as to minimize potential for corrosion; chemicals that are incompatible are not stored or handled together; all chemicals are conducted from the feeder to the point of application in separate conduits; chemical feeders are as near as practical to the feed point; chemical feeders and pumps operate at no lower than twenty per cent (20%) of the feed range unless two (2) fully independent adjustment mechanisms such as pump pulse rate and stroke length are fitted when the pump shall operate at no lower than ten (10) percent of the rated maximum; and chemicals are fed by gravity where practical.7.1.d. Chemical information. -- For each chemical the information shall include: specifications for the chemical to be used; purpose of the chemical; proposed minimum non-zero, average and maximum dosages, solution strength or purity (as applicable), and specific gravity or bulk density; and method for independent calculation of amount fed daily.7.2. Feed Equipment. 7.2.a. Number of feeders. -- Where chemical feed is necessary for the protection of the supply, such as chlorination, coagulation or other essential processes, the standby unit or a combination of units of sufficient capacity shall be available to replace the largest unit when it is out of service. The standby unit or a combination of units of sufficient capacity shall be available to replace the largest unit during shut-downs. A separate feeder shall be used for each chemical applied. Spare parts shall be available for all equipment to replace parts that are subject to wear and damage.7.2.b. Control. -- Feeders may be manually or automatically controlled, with automatic controls designed to allow override by manual controls. Process shall be manually started following shutdown, unless otherwise approved by the BPH. At automatically operated facilities, chemical feeders shall be electrically interconnected with the well or service pump. Chemical feed rates shall be proportional to the flow stream being dosed. A means to measure the flow stream shall be provided in order to determine chemical feed rates. Provisions shall be made for measuring the quantities of chemicals used. Automatic chemical dose or residual analyzers may be approved by the BPH for use and shall provide alarms for critical values and recording charts. 7.2.b.1. Weighing scales. -- Weighing scales shall be provided for weighing cylinders at all plants utilizing chlorine gas; shall be required for fluoride solution fed from supply drums or carboys; should provide for volumetric dry chemical feeders; shall be capable of providing reasonable precision in relation to average daily dose. Where conditions warrant, for example with rapidly fluctuating intake turbidity, coagulant and coagulant aid addition may be made according to turbidity, streaming current or other sensed parameter.7.2.c. Dry chemical feeders. -- Dry chemical feeders shall measure chemicals volumetrically or gravimetrically, provide adequate solution/slurry water and agitation of the chemical at the point of placing solution/slurry, completely enclose chemicals to prevent emission of dust to the operating room.7.2.d. Positive displacement solution pumps. -- Positive displacement type solution feed pumps shall: be used to feed liquid chemicals but shall not be used to feed chemical slurries; be capable of operating at the required maximum rate against the maximum head conditions found at the point of injection; be provided with calibration tubes or mass flow monitors which allow for direct physical measurement of actual feed rates; and have a pressure relief valve on the pump discharge line.7.2.e. Liquid chemical feeders. -- Siphon control -- Liquid chemical feeders shall be such that chemical solutions cannot be siphoned into the water supply by assuring discharge at a point of positive pressure or by providing vacuum relief, a suitable air gap, or anti-sipon device, or other suitable means or combinations as necessary.7.2.f. Cross-connection control. -- Cross-connection control shall be provided to assure that the service water lines discharging to liquid storage tanks are properly protected from backflow as required by the BPH. Design shall prevent chemical solutions or slurries from being siphoned through solution feeders into the water supply, and no direct connection shall exist between any sewer and a drain or overflow from the feeder, solution chamber or tank by providing that all drains terminate at least six (6) inches or two (2) pipe diameters, whichever is greater, above the overflow rim of a receiving sump, conduit or waste receptacle.7.2.g. Chemical feed equipment location. -- Chemical feed equipment shall: be located in a separate room to reduce hazards and dust problems; be conveniently located near points of application to minimize length of feed lines; be readily accessible for servicing, repair, and observation of operation including cleanouts; be located such that the flow to the rapid mix is by gravity, except in case of in-line static mixers; be located with protective curbing so that chemicals from equipment failure, spillage or accidental drainage shall not enter the water in conduits, treatment or storage basins; and have floor drains to facilitate area cleaning.7.2.h. In-Plant water supply. -- The in-plant water supply shall be: only from a safe, source approved by the BPH, ample in quantity and adequate in pressure; provided with means for measurement when preparing specific solution concentrations by dilution; properly treated for hardness, when necessary; and properly protected against backflow as approved by the BPH.7.2.i. Storage of chemicals. -- Space shall be provided for at least thirty (30) days of chemical supply, the convenient and efficient handling of chemicals, dry storage conditions, and a minimum storage volume of 11/2 truckloads where purchase is by truckload lots. Storage tanks and pipelines for liquid chemicals shall be specific to the chemicals and not for alternates. Where possible, connectors for each liquid chemical shall be different and distinctly marked. Chemicals shall be stored in covered or unopened shipping containers, unless the chemical is transferred into a storage unit approved by the BPH. Liquid chemical storage tanks shall have a liquid level indicator, have an overflow and a receiving basin or drain capable of containing accidental spills or overflows, provide for sufficient containment volume to prevent accidental discharge in the event of failure of the largest tank.7.2.j. Bulk liquid storage tanks. -- A means shall be provided in a solution tank to maintain a uniform strength of solution. Continuous agitation shall be provided to maintain slurries in suspension. A means to assure continuity of chemical supply while servicing a liquid storage tank shall be provided. Means shall be provided to measure the liquid level in the tank. Liquid storage tanks shall be kept covered. Large liquid storage tanks with access openings shall have the openings curbed and fitted with overhanging covers. Subsurface locations for solution tanks shall be free from sources of possible contamination and assure positive drainage for groundwater, accumulated water, chemical spills and overflows. Overflow pipes, when provided, shall be turned downward, with the end screened, have a free fall discharge, and be located where noticeable. Liquid storage tanks shall be vented, but not through vents in common with day tanks. Acid storage tanks shall be vented to the outside atmosphere. Each tank shall be provided with a valved drain and be protected against cross-connections. Liquid storage tanks shall be located with protective curbing so that chemicals from equipment failure, spillage or accidental drainage shall not enter the water in conduits, treatment or storage basins. Secondary containment volumes shall be able to hold the volume of the largest storage tank. Piping shall be designed to minimize or contain chemical spills in the event of pipe ruptures.7.2.k. Day tanks. -- Day tanks shall be provided where bulk storage of liquid chemical is provided, however, the BPH may allow chemicals to be fed directly from shipping containers no larger than fifty-five (55) gallons. Day tanks shall meet all the requirements of bulk liquid storage tanks, except that shipping containers do not require overflow pipes and drains. Day tanks shall hold no more than a thirty (30) hour supply, but no less than a one (1) day of operation supply at design flow. Day tanks shall be scale-mounted or have a calibrated gauge painted or mounted on the side if liquid level can be observed in a gauge tube, manometer or through translucent sidewalls of the tank. In opaque tanks, a gauge rod extending above a reference point at the top of the tank, attached to a float, may be used. Except for fluosilicic acid, hand pumps may be provided for transfer from a shipping container. A tip rack may be used to permit withdrawal into a bucket from a spigot. Where motor-driven transfer pumps are provided, a liquid level limit switch shall be provided. A means which is consistent with the nature of the chemical solution shall be provided to maintain uniform chemical strength in a day tank. Continuous agitation shall be provided to maintain chemical slurries in suspension. Tanks and tank refilling line entry points shall be clearly labeled with the name of the chemical contained. Filling of day tanks shall not be automated, unless authorized by the BPH.7.2.l. Feed lines. -- Feed lines: shall be as short as possible, and of durable, corrosion-resistant material, easily accessible throughout the entire length, protected against freezing, and readily cleaned; shall slope upward from the chemical source to the feeder when conveying gases; shall be designed consistent with scale-forming or solids depositing properties of the water, chemical, solution or mixtures conveyed; and shall be color coded and labeled.7.2.m. Handling. -- Carts, elevators and other appropriate means shall be provided for lifting chemical containers to minimize excessive lifting by operators. Provisions shall be made for disposing of empty bags, drums or barrels by an approved procedure that minimizes exposure to dusts. Provision shall be made for the proper transfer of dry chemicals from shipping containers to storage bins or hoppers in such a way as to minimize the quantity of dust that may enter the room in which the equipment is installed. Control shall be provided by use of vacuum pneumatic equipment or closed conveyor systems; facilities for emptying shipping containers in special enclosures; or for exhaust fans and dust filters that put the hoppers or bins under negative pressure. Provision shall be made for measuring quantities of chemicals used to prepare feed solutions.7.2.n. Housing. -- Floor surfaces shall be smooth and impervious, slip-proof and well drained. Vents from feeders, storage facilities and equipment exhaust shall discharge to the outside atmosphere above grade and remote from air intakes and doors.7.3. Chemicals. 7.3.a. Shipping containers. -- Chemical shipping containers shall be fully labeled to include the chemical's name, purity and concentration and supplier name and address.7.3.b. Specifications. -- Chemicals shall meet AWWA specifications and shall conform to ANSI/NSF Standard 60: Drinking Water Treatment Chemicals - Health Effects where applicable.7.3.c. Assay. -- Provisions may be required for the assay of chemicals delivered.7.4. Operator Safety. 7.4.a. Ventilation. -- Special provisions shall be made for ventilation of chlorine feed and storage rooms.7.4.b. Respiratory protection equipment. -- Respiratory protection equipment, meeting the requirements of the National Institute for Occupational Safety and Health (NIOSH), shall be available where chlorine gas is handled 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 thirty (30) minute capacity and be compatible with or exactly the same as units used by the fire department responsible for the plant.7.4.c. Chlorine leak detection. -- A bottle of ammonium hydroxide, fifty-six percent (56%) ammonia solution, shall be available for chlorine leak detection. Where ton containers are used, a leak repair kit approved by the Chlorine Institute shall be provided. Where pressurized chlorine gas is present, continuous chlorine leak detection equipment is required and shall be equipped with both an audible alarm and a warning light.7.4.d. Protective equipment. -- The public water system shall provide each operator at least one (1) pair of rubber gloves, a dust respirator of a type meeting NIOSH requirements for toxic dusts, an apron or other protective clothing and goggles or face mask. A deluge shower and eye-washing device shall be installed where strong acids and alkalis are used or stored. A water holding tank that allows water to come to room temperature shall be installed in the water line feeding the deluge shower and eye-washing device. Other methods of water tempering may be considered on an individual basis. Other protective equipment shall be provided as necessary.7.5. Specific Chemicals. 7.5.a. Chlorine gas. -- Chlorine gas feed and storage shall be enclosed, sealed and separated from other operating areas. The chlorine room shall be provided with a shatter resistant inspection window installed in an interior wall, constructed in such a manner that all openings between the chlorine room and the remainder of the plant are sealed and provided with doors equipped with panic hardware assuring a ready means of exit and opening outward only to the building exterior. 7.5.a.1. Full and empty cylinders of chlorine gas shall be isolated from operating areas, restrained in position to prevent upset, stored in rooms separate from ammonia storage and stored in areas not in direct sunlight or exposed to excessive heat.7.5.a.2. Where chlorine gas is used, adequate housing shall be provided for the chlorination equipment and for storing chlorine. The room shall be constructed to provide the following: a ventilating fan designed specifically to handle chlorine gas with a capacity that provides one complete air change per minute when the room is occupied; the ventilating fan shall take suction near the floor as far as practical from the door and air inlet, with the point of discharge located so as not to contaminate air inlets or entrance doors to any rooms or structures; air inlets shall be through corrosion resistant louvers near the ceiling; and louvers for chlorine room air intake and exhaust shall facilitate airtight closure. Separate switches for the fan and lights shall be located outside of the chlorine room and at the inspection window. Outside switches shall be protected from vandalism. A signal light indicating fan operation shall be provided at each entrance when the fan can be controlled from more than one point. Vents from feeders and storage shall discharge to the outside atmosphere, above grade. The room location shall be on the prevailing downwind side of the building away from entrances, windows, louvers, walkways, etc. Floor drains are discouraged. Where provided, the floor drains shall discharge to the outside of the building and shall not be connected to other internal or external drainage systems. Where located near residential or developed areas and deemed necessary by the BPH, provision shall be made to chemically neutralize chlorine gas before discharge from the water treatment plant building into the environment. Such equipment shall be designed as part of the chlorine gas storage and feed areas to automatically engage in the event of any measured chlorine release. The equipment shall be sized to treat the entire contents of the largest storage container on site.7.5.a.3. Chlorinator rooms shall be heated to sixty (60) degrees F and be protected from excessive heat. Cylinders and gas lines shall be protected from temperatures above that of the feed equipment.7.5.a.4. Pressurized chlorine feed lines shall not carry chlorine gas beyond the chlorinator room.7.5.b. Acids and caustics. -- Acids and caustics shall be kept in closed corrosion-resistant shipping containers or bulk liquid storage tanks with the contents identified by signs or placards. Acids and caustics shall not be handled in open vessels but shall be pumped in undiluted form from original containers through suitable hose to the point of treatment or to a covered day tank.7.5.c. Sodium chlorite for chlorine dioxide generation. -- Proposals for the storage and use of sodium chlorite shall be approved by the BPH prior to the preparation of final plans and specifications. Provisions shall be made for proper storage and handling of sodium chlorite to eliminate any danger of fire or explosion associated with its powerful oxidizing nature. 7.5.c.1. Storage. -- Sodium chlorite shall be stored by itself in a separate room and preferably shall be stored in an outside building detached from the water treatment facility. It shall be stored away from organic materials that would react violently with sodium chlorite. The storage structures shall be constructed of noncombustible materials. If the storage structure is located in an area where a fire may occur, water shall be available to keep the sodium chlorite area cool enough to prevent decomposition from heat and the resultant explosive conditions.7.5.c.2. Handling. -- Care shall be taken to prevent spillage. An emergency plan of operation shall be available for the clean-up of any spillage. Storage drums shall be thoroughly flushed prior to being recycled or disposed.7.5.c.3. Feeders. -- Positive displacement feeders shall be provided. Tubing for conveying sodium chlorite or chlorine dioxide solutions shall be Type 1 PVC, polyethylene or materials recommended by the manufacturer. Chemical feeders may be installed in gas chlorine rooms if sufficient space is provided for facilities meeting the chlorine room requirements. Feed lines shall be installed in a manner to prevent formation of gas pockets and shall terminate at a point of positive pressure. Check valves shall be provided to prevent the backflow of chlorine into the sodium chlorite line.7.5.d. Sodium Hypochlorite. -- Storage and handling procedures shall be arranged to minimize the slow natural decomposition process of sodium hypochlorite either by contamination or by exposure to more extreme storage conditions. In addition, feed rates shall be regularly adjusted to compensate for this progressive loss in chlorine content. 7.5.d.1. Storage. -- Sodium hypochlorite shall be stored in the original container or in sodium hypochlorite compatible bulk liquid storage tanks. Storage containers or tanks shall be located out of sunlight in a cool area and shall be vented to the outside of the building. Whenever feasible, stored sodium hypochlorite shall be pumped undiluted to the point of addition. Where dilution is unavoidable, deionized or softened water should be used. Storage areas, tanks, and pipe work shall be designed to avoid the possibility of uncontrolled discharges and a sufficient amount of appropriately selected spill absorbent shall be stored on-site.7.5.d.2. Feeders. -- Positive displacement pumps with sodium hypochlorite compatible materials for wetted surfaces shall be used. To avoid air locking in smaller installations, small diameter suction lines shall be used with foot valves and degassing pump heads. In larger installations flooded suction shall be used with pipe work arranged to ease escape of gas bubbles. Calibration tubes or mass flow monitors which allow for direct physical checking of actual feed rates shall be provided. Injectors shall be made removable for regular cleaning where hard water is to be treated.7.5.e. Ammonia. -- Ammonia for chloramines formation may be added to water either as a water solution of ammonium sulfate, or as aqua ammonia, or as anhydrous ammonia (purified 100% ammonia in liquid or gaseous form). 7.5.e.1. Ammonium sulfate. -- A water solution is made by the addition of ammonium sulfate solid to water with agitation. The tank and dosing equipment contact surfaces shall be made of corrosion resistant non-metallic materials. Provisions shall be made for removal of the agitator after dissolving the solid. The tank shall be fitted with an air-tight lid and vented outdoors. The application point shall be at the center of treated water flow at a location where there is high velocity movement.7.5.e.2. Aqua ammonia (ammonium hydroxide). -- Aqua ammonia feed pumps and storage shall be enclosed and separated from other operating areas. The aqua ammonia room shall be equipped as per a chlorine gas room with the following changes: Corrosion resistant, closed, unpressurized tank shall be used for bulk liquid storage and day tanks, vented through inert liquid traps to a high point outside; an incompatible connector or lockout provisions shall be provided to prevent accidental addition of other chemicals to the bulk liquid storage tank(s); the bulk liquid storage tank(s) shall be designed to avoid conditions where temperature increases cause the ammonia vapor pressure over the aqua ammonia to exceed atmospheric pressure by refrigeration or other means of external cooling, or by dilution and mixing of the contents with water without opening the bulk liquid storage tank; an exhaust fan shall be installed to withdraw air from high points in the room and makeup air shall be allowed to enter at a low point; the aqua ammonia shall be conveyed directly from a day tank to the treated water stream injector without the use of a carrier water stream unless the carrier stream is softened; the application point shall be placed in a region of rapid, preferably turbulent, water flow; provisions shall be made for easy access for removal of calcium scale deposits from the injector; and provisions of a modestly-sized scrubber capable of handling occasional minor emissions should be considered.7.5.e.3. Anhydrous ammonia. -- Anhydrous ammonia is readily available as a pure liquefied gas under moderate pressure in cylinders or as a cryogenic liquid boiling at -15 Celsius at atmospheric pressure. The liquid causes severe burns on skin contact. Anhydrous ammonia and storage feed systems (including heaters where required) shall be enclosed and separated from other work areas and constructed of corrosion resistant materials. Pressurized ammonia feed lines shall be restricted to the ammonia room. An emergency air exhaust system with an elevated intake shall be provided in the ammonia storage room. Leak detection systems shall be provided in all areas through which ammonia is piped. Special vacuum breaker/regulator provisions must be made to avoid potentially violent results of backflow of water into cylinders or storage tanks. Carrier water systems of soft or pre-softened water may be used to transport ammonia to the application point and to assist in mixing. The ammonia injector should use a vacuum eductor or consist of a perforated tube fitted with a closely fitting flexible rubber tubing seal punctured with a number of small slits to delay fouling by lime or other scale deposits. Provisions shall be made for periodic removal of lime or other scale deposits from injectors and carrier piping. Consideration shall be given to the provision of an emergency gas scrubber capable of absorbing the entire contents of the largest anhydrous ammonia storage unit whenever there is a risk to the public as a result of potential ammonia leaks.7.5.f. Potassium permanganate. -- A source of heated water should be available for dissolving potassium permanganate and mechanical mixers shall be provided.7.5.g. Fluoride - At least two (2) diaphragm operated anti-siphon devices shall be provided on all fluoride saturator or fluosilicic acid feed systems with one (1) diaphragm operated anti-siphon device to be located on the discharge side of the feed pump and one (1) to be located at the point of application. A physical break box is required in high hazard situations where the application point is substantially lower than the metering pump. In this situation, either a dual head feed pump or two (2) separate pumps are required and the anti-siphon device at the discharge side of the pump may be omitted. The point of application shall enter into the lower half of the pipe, preferably at a forty-five (45) degree angle from the bottom of the pipe and shall protrude into the pipe one third of the pipe diameter.7.6. Other chemical feed system or treatment methodologies may be installed in accordance with manufacturers and industry recommendations if approved by the BPH.