Water storage vessels

Water storage vessels. Water storage vessels. The department recommends that pressure tanks be sufficiently sized to provide the minimum pump run time recommended by the pump manufacturer. (1) Pressure tanks. (a) General. Tanks relying on expansion of a flexible membrane within a restricting container, rather than on a water to air interface to provide pressure in the water system, may be used. All pressure tanks for storing potable water under pressure, including those having an air space for expansion, shall be identified by seal, label or plate indicating the manufacturers name and model number and shall meet the following specifications: 1. Pressure tanks to be buried shall be constructed of steel, fiberglass, or other comparable non-metallic composite material. Steel tanks with metallic discharge piping, meeting the requirements of s. NR 812.28 , shall be used in contaminated soil areas. Steel tanks to be buried shall have a minimum wall thickness of 0.25 inches and shall have an identifying seal, label, or plate showing the manufacturer’s name and model number. Fiberglass or other non-metallic tanks to be buried shall have the structural strength to prevent collapse of the tank. Manufacturer’s instructions shall be followed. All buried tanks shall be back-filled in place with sand, compacted in place. Steel pitless receiver tanks, when they are part of a pitless unit attached directly to the well casing pipe, shall also have a minimum wall thickness of 0.25 inches. Any air unloader pipe, tank air valve, or any other pipe connection extending up to the ground surface shall be steel pipe meeting the requirements of s. NR 812.28 and shall terminate at least 12 inches above ground grade. 2. Pressure tanks having a gross volume in excess of 500 gallons, and not having a water to air interface bladder, shall have the following: a. If the tank is buried, all electrical controls extended to at least above ground grade. b. Each tank shall have an access manhole, a drain, and pressure gauge, pressure relief valve, water sight glass and pressure or probe operated controls for the pumps. c. An air compressor or other suitable means to add air to the tank. d. Any interior protective materials including but not limited to liners, paints, coatings,or sealants shall be certified for potable water use under NSF Standard 61. (b) Pressure tanks larger than 1,000 gallons gross volume. An approval shall be obtained for pressure tanks having a gross volume greater than 1,000 gallons. The department recommends that pressure tanks having a volume greater than 1,000 gallons be installed above ground. When approved, the tank shall be installed according to the requirements of par. (a) . When tanks of this size are approved for burial, the head end of the tank shall be cradled in a basement wall or in the wall of an approved pit to provide access and shall be constructed to the specifications for pits described in s. NR 812.36 (2) to provide access to the head of the tank. The pit shall have other additional support cradles. Pitless receiver tanks having a volume greater than 1,000 gallons may be installed without an access pit. (2) Nonpressure storage vessels. All nonpressure storage vessels shall meet all of the following requirements, as applicable: (a) Approvals. Prior department approval under s. NR 812.09 is required for all of the following: 1. Any reservoir located prior to the entry point into a potable water system. 2. A nonpressure storage vessel, except for a surge tank, that is located prior to the entry point into the distribution system of a potable non-community water system. 3. A nonpressure storage vessel for potable water made of a material not meeting the specifications of par. (b) 1. (b) General specifications. All nonpressure storage vessels shall meet all of the following specifications: 1. ‘Material.’ Reservoirs shall be constructed of steel or reinforced concrete. Nonpressure storage vessels located entirely above ground shall be made of stainless steel, poured concrete, or high-grade plastic. Concrete used to construct a nonpressure storage vessel shall be mixed according to the requirements specified under s. NR 812.11 (15) (e) . 2. ‘Location.’ Reservoirs shall meet the location requirements of s. NR 812.08 . Nonpressure storage vessels located entirely above ground and elevated nonpressure storage vessels shall be placed in a location that provides convenient access for inspection and maintenance. 3. ‘Access.’ Nonpressure storage vessels shall be provided with a manhole that is at least 20 inches in diameter or 20 inches square for cleaning and maintenance. 4. ‘Inflow piping.’ Above-ground inflow pipes shall enter the nonpressure storage vessel a minimum of 2 pipe diameters above the overflow elevation within the nonpressure vessel to maintain an air gap. Buried inflow pipe shall be maintained under a continuous positive pressure head that is greater than the ground surface elevation. 5. ‘Overflow piping.’ Nonpressure storage vessels shall be provided with an overflow pipe that discharges at least 12 inches above ground grade and discharges onto a splash plate or other hard, non-erodible surface. The end of the overflow pipe shall be fitted with an attached screen that is adequate to prevent entry of vermin into the storage tank. 6. ‘Cover.’ The cover of any nonpressure storage vessel shall seal well enough to prevent water, vermin, and insects from entering. 7. ‘Steel construction specifications.’ Steel nonpressure storage vessels shall meet the requirements for welded construction of AWWA D100-21, dated November 1, 2021, or the requirements for bolted construction of AWWA D103-19, dated January 1, 2020, which are incorporated by reference. (c) Reservoirs. A reservoir may be constructed or installed to store water if it is constructed or installed above the groundwater level and in accordance with the requirements of par. (b) and this paragraph. Concrete reservoir construction features are shown in Figure 7 of ch. NR 812 Appendix . Reservoirs constructed of concrete shall meet all of the following specifications: 1. ‘Pipes.’ The supply pipe and overflow pipe shall extend through the structure. 2. ‘Joints and drain.’ Wall construction joints shall have an impervious flexible water stop strip, and a reservoir drain shall be installed before the concrete is poured. 3. ‘Floor.’ The floor of the reservoir shall be reinforced poured concrete with a thickness of at least 6 inches and shall have a curbing wall 6 inches high and 6 inches thick with a keyway or a flexible water stop strip for a construction joint with the walls. 4. ‘Walls.’ The walls of the reservoir shall be reinforced poured concrete at least 6 inches thick and shall terminate above the established ground surface. 5. ‘Roof.’ The roof shall be reinforced poured concrete at least 6 inches thick and shall extend at least 12 inches above the established ground surface. An access manhole at least 20 inches in diameter or 20 inches square shall be constructed as an integral part of the roof. The manhole shall have a curbing wall extending at least 12 inches above the roof. The manhole shall be constructed entirely of 4-inch-thick reinforced poured concrete or shall be fabricated of a 0.25-inch steel or cast-iron frame with a gasket and bolted cover. The curbing shall be provided with a snug-fitting, overlapping cover with a minimum of 3-inch-wide skirted sides. The cover shall be constructed with welded sheet steel or reinforced poured concrete. Concrete shall be mixed according to the requirements specified under s. NR 812.11 (15) (e) . (3) Painting and cathodic protection. Metal surfaces of reservoirs or elevated storage tanks, to be in contact with potable water, shall be protected by paints, other protective coatings, or by cathodic protection except when documentation is provided to the department that the source water will not be aggressive or corrosive to the metal surfaces. Paint or coating systems shall conform with AWWA standard D102 and shall be NSF approved for use with potable water. When cathodic protection is to be provided, it shall be designed and installed by competent technical personnel. A copy of the AWWA standards are available for inspection at the office of the department of natural resources and the office of the legislative reference bureau, and may be obtained for personal use from AWWA, Inc., 6666 W. Quincy Avenue, Denver, Colorado 80235.