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WA9601-CS 990621 (2) ~,~%o -- American water Works Association ANSI/AWWA C652-92 (Revision of ANSI/AWWA C652-86) AWWA STANDARD FOR DISINFECTION OF WATERiSTORAGE FACILITIES SECTION 1: GENERAL Sec. 1.1 Scope This standard for disinfection of water-storage facilities covers materials, facil- ity preparation, application of disinfectant to interior surfaces of facilities, and sampling and testing for the presence of coliform bacteria. The standard also includes disinfection procedures for underwater inspection of on-line, potable-water- storage facilities, but does not cover the technical aspects of underwater inspection. All new storage facilities shall be disinfected before they are placed in service. All storage facilities taken out of service for inspecting, repairing, painting, cleaning, or other activity that might lead to contamination of water shall be disinfected before they are returned to service. Sec. 1.2 References / This standard references the following documents. The latest current edition of each document forms a part of this standard where and to the extent specified herein. In case of any conflict, the requirements of this standard shall prevail. ANSI*/AWWA B300---Standard for Hypochlorites. ANSI/AWWA B301--Standard for Liquid Chlorine. Standard Methods for the Examination of Water and Wastewater. APHA,'~ AWWA, and WEF.~ Washington, D.C. (18th ed., 1992). *American National Standards Institute Inc., 11 W. 42nd St., New York, NY 10036. ?American Public Health Association, 1015 15th St. N.W., Washington, DC 20005. ~;Water Environment Federation, 601 Wythe St., Alexandria, VA 22314. 1 2 AWWA C,652-92 Additional materials relating to activity under this standard include the following: Chlorine Manual---Chlorine Institute Inc.* Introduction to Water Treatment. WSO Series, Vol. 9.. AWWA, Denver (1984). Material safety data sheets for forms of chlorine used (provided by suppliers). Safety Practice for Water Utilities. AWWA Manual M3. AWWA, Denver (1990). Water Chlorination Principles and Practices. AWWA Manual Mg~0. AWWA, Denver (1973). Water Quality and Treatment. AWWA, Denver (4th ed., 1990). Sec. 1.3 Record of Compliance The record of compliance shall be the bacteriological test results certifying that the water held in the storage facility is free of coliform bacteria contamination. SECTION 2: CLEANING All scaffolding, planks, tools, rags, and other materials not part of the struc- tural or operating facilities of the tank shall be removed. Then the surfaces of the walls, floor, and operating facilities of the storage facility shall be cleaned thoroughly using a high-pressure water jet, sweeping, scrubbing, or equally effective means. All water, dirt, and foreign material accumulated in this cleaning operation shall be discharged from the storage facility or otherwise removed. Sec. 2.1 Other Materlain Following the cleaning operation, the vent screen, overflow screen, and any other screened openings shall be checked and put in satisfactory condition to pre- vent birds, insects, and other possible contaminants from entering the facility. Any material required to be in the operating storage facility after the cleaning procedure has been completed shall be clean and sanitary when placed in the facility. In such instances, care shall be taken to minimize the introduction of dirt or other foreign material. (For example, placing a layer of limestone granules on the unpainted bottom of the storage facility to prevent corrosion.) SECTION 3: FORMS OF CHLORINE FOR DISINFECTION The forms of chlorine that may be used in the disinfecting operations are liquid chlorine, sodium hypochlorite solution, and calcium hypoehlorite granules or tablets. See. 3.1 Liquid Chlorine Liquid chlorine conforming to ANSI/AWWA B301 contains 100 percent avail- able chlorine and is packaged in steel containers usually of 100-1b, 150-1b, or 1-ton (45.4-kg, 68.0-kg, or 907.2-kg) net chlorine weight. Liquid chlorine shall be used only (1) in combination with appropriate gas-flow chlorinators and ejectors to provide a *Chlorine Institute Inc., 2001 L St. N.W., Washington, DC 20036. DISI ION OF WATER FACILITIES 3 controlled high-concentration solution feed to the water to be chlorinated; (2) under ' the direct supervision of a person who is familiar with chlorine's physiological, ' chemical, and physical properties, and who is trained and equipped to handle any emergency that may arise; and (3) when appropriate safety practices are observed to protect working personnel and the public. Sec. 3.2 Sodium Hypochlorite Sodium hypochlorite conforming to ANSI/AWWA B300 is available in liquid form in glass, rubber-lined, or plastic containers typically ranging in size from i qt (0.95 L) to 5 gal (18.92 L). Containers of 30 gal (113.6 L) or larger may be available in some areas. Sodium hypochlorite contains approximately 5 percent to 15 percent available chlorine by volume, and care must be taken to control storage conditions and length of storage to minimize its deterioration. Sec. 3.3 Calcium Hypochlorite Calcium hypochlorite conforming to ANSI/AWWA B300 is available in granular form or in small tablets, and contains approximately 65 percent available chlorine by weight. The material should be stored in a cool, dry, dark environment to mini- mize its deterioration. SECTION 4: ALTERNATIVE METHODS OF CHLORINATION C Three methods of chlorination are explained in this standard. Typically, only -. one method will be used for a given storage-facility disinfection, but combinations of the methods may be used. The three methods are (1) chlorination of the full storage facility such that, at the end of the appropriate retention period, the water will have a free chlorine residual of not less than 10 mg/L; (2) spraying or painting of all storage facility water-contact surfaces with a solution of 200-mg/L available chlorine; and (3) chlorination of full storage facility with water having a free chlorine residual of 2 mg/L after 24 h.* Sec. 4.1 Chlorination Method 1 The water-storage facility shall be filled to the overflow level with potable water to which enough chlorine is added to provide a free chlorine residual in the full facility of not less than 10 mg/L at the end of the appropriate 6-h or 24-h period, as described in Sec. 4.1.4. The chlorine, either as calcium hypochlorite, sodium hypo- chlorite, or liquid chlorine, shall be introduced into the water as described hereafter. 4.1.1 Liquid-chlorine use. Liquid chlorine shall be introduced into the water filling the storage facility in such a way as to give a uniform chlorine concentration during the entire filling operation. Portable chlorination equipment shall be care- fully operated and shall include a liquid-chlorine cylinder, gas-flow chlorinator, chlorine ejector, safety equipment, and an appropriate solution tube to inject the high-concentration chlorine solution into the filling water. The solution tube shall be *For reference, amounts of chemicals needed for various chlorine concentrations are shown in appendix A, Table A. 1. 4 AV4,rV~A C652-92 inserted through an appropriate valve located on the inlet pipe and near the storage facility such that the chlorine solution will mix readily with the in~owing water. 4.1.2 Sodium hypochlorite use. Sodium hypochlorite shall be added to the water entering the storage facility by means of a chemical-feed pump, or shall be applied by hand-pouring into the storage facility and allowing the infiowing water to provide the desired mixing. 4.1.2.1 When a chemical-feed pump is used, the concentrated chlorine solution shall be pumped through an appropriate solution tube so as to inject the high- concentration chlorine solution at a rate that will give a uniform chlorine concentration in the filling water. The solution tube shall be inserted through an appropriate valve located on the inlet pipe and near the storage facility, or through an appropriate valve located on the storage facility such that the chlorine solution will mix readily with the filling water. 4.1.2.2 When the sodium hypochlorite is poured into the storage facility, the filling of the storage facility shall begin immediately thereafter or as soon as any removed manhole covers can be closed. The sodium hypochlorite may be poured through the cleanout or inspection manhole in the lower course or level of the stor- age facility, in the riser pipe of an elevated tank, or through the roof manhole. The sodium hypochlorite shall be poured into water in the storage facility when such water is not more than 3 ft (0.9 m) in depth, nor less than 1 f~ (0.3 m) in depth or as close thereto as manhole locations permit. 4.1.3 Calcium hypochlorite use. Calcium hypochlorite granules or tablets bro- ken or crushed to sizes not larger than l/4-in. (6.4-mm) maximum dimension may be poured or carried into the storage facility through the cleanout or inspection man- hole in the lower course or level of the storage facility, into the riser pipe of an elevated tank, or through the roof manhole. The granules or tablet particles sha'll be placed in the storage facility before flowing water into it. The granules or tablets shall be located so that the infiowing water will ensure a current of water circulat- ing through the calcium hypochlorite, dissolving it during the filling operation. The calcium hypochlorite shall be placed only on dry surfaces unless adequate precau- tions are taken to provide ventilation or protective breathing equipment. 4.1.4 Retention period. After the storage facility has been filled with the disin- fecting water, it shall stand full as follows: (1) for a period of not less than 6 h when the water entering the storage facility has been chlorinated uniformly by gas-feed equipment or chemical pump, or (2) for a period of not less than 24 h when the storage facility has been filled with water that has been mixed with sodium hypo- chlorite or calcium hypochlorite within the storage facility as described in Sec. 4.1.2 and Sec. 4.1.3. 4.1.5 Handling of disinfection water. After the retention period stated in Sec. 4.1.4, the free chlorine residual in the storage facility shall be reduced to a concentration appropriate for distribution (not more than 2 mg/L) by completely draining the storage facility and refilling with potable water, or by a combination of additional holding time and blending with potable water having a low chlorine con- centration. When an appropriate chlorine concentration is reached and subject to satisfactory bacteriological testing and acceptable aesthetic quality, such water may be delivered to the distribution system. 4.1.5.1 The environment into which the chlorinated water is to be discharged shall be inspected, and if there is any likelihood that the chlorinated discharge will cause damage, then a reducing agent shall be applied to the water to be wasted to thoroughly neutralize the chlorine residual in the water. Federal, state, or local ION OF WATER FACIL1TIY~ 5 environmental regulations may require special provisions or permits prior to dis- ' posal of highly chlorinated water. The proper authorities should be contacted prior to disposal of highly chlorinated water. Sec. 4.2 Chlorlnation Method 2 A solution of 200-mg/L available chlorine shall be applied directly to the sur- faces of all parts of the storage facility that would be in contact with water when the storage facility is full to the overflow elevation. 4.2.1 Method of application. The chlorine solution may be applied with suit- able brushes or spray equipment. The solution shall thoroughly coat all surfaces to be treated, including the inlet and outlet piping, and shall be applied to any sepa- rate drain piping such that it will have available chlorine of not less than 10 mg/L when filled with water. Overflow piping need not be disinfected. 4.2.2 Retention. The disinfected surfaces shall remain in contact with the strong chlorine solution for at least 30 min, afser which potable water shall be admitted, the drain piping purged of the 10-mg/L chlorinated water, and the storage facility then filled to its overflow level. Following this procedure, and subject to satisfactory bacteriological testing and acceptable aesthetic quality, such water may be delivered to the distribution system. Sec. 4.3 ChlorlnAtion Method 3 Water and chlorine shall be added to the storage facility in amounts such that the solution will initially contain 50 mg/L available chlorine and will fill approxi- mately 5 percent of the total storage volume. This solution shall be held in the storage facility for a period of not less than 6 h. The storage facility shall then be r filled to the overflow level by flowing potable water into the highly chlorinated =.. water. It shall be held full for a period of not less than 24 h. All highly chlorinated water shall then be purged from the drain piping. Following this procedure, and subject to satisfactory bacteriological testing and acceptable aesthetic quality, the remaining water may be delivered to the distribution system. 4.3.1 Adding chlorine. Chlorine shall be added to the storage facility by the method described in Sec. 4.1.1, Sec. 4.1.2, or Sec. 4.1.3. The actual volume of the 50-mg/L chlorine solution shall be such that, after the solution is mixed with filling water and the storage facility is held full for 24 h, there will be a free-chlorine residual of not less than 2 mg/L. ~ Sec. 4A Bacteriological Sampling and Testing After the chlorination procedure is completed, and before the storage facility is placed in service, water from the full facility shall be sampled and tested for coli- form organisms in accordance with the latest edition of Standard Methods for the Examination of Water and Wastewater. The testing method used shall be either the multiple-tube fermentation technique or the membrane-filter technique. 4.4.1 Test for odor. The water in the full facility should also be tested to assure that no offensive odor exists due to chlorine reactions or excess chlorine residual. 4.4.2 Results of testing. If the test for coliform organisms is negative, then the storage facility may be placed in service. If the test shows the presence of coliform bacteria, then the situation shall be evaluated by a qualified engineer. In any event, repeat samples shall be taken until two consecutive samples are negative, or the storage facility shall again be subjected to disinfection.