NR 812.32(9)(c)3. 3. When necessary, overflow piping shall be installed to prevent flow of water up the outside of the well casing pipe or to prevent freezing of water inside the casing. When installed, the flow of water from the discharge pipe shall be limited to a minimum so as to preserve groundwater and water pressure. The overflow pipe shall be installed to extend through the well cap or seal or shall extend off a surge tank in the basement. The overflow pipe may be attached to the outside wall of the well casing pipe if both the point of exit from the well casing pipe and the terminus of the overflow are at least 12 inches above the ground grade and the connection to the well casing pipe is watertight. The overflow pipe shall terminate at least 2 pipe diameters above any drain inlet at the well site, in a building or in a building basement. If the overflow is installed at the well head, the overflow shall extend at least 2 feet above the regional flood elevation and a free air gap of at least 2 pipe diameters above the drain shall be provided. The receiving drain shall discharge to the ground or to a gravel pocket at a point at least 8 feet from the well. A funnel receptacle shall be installed on the inlet of the drain to accept all of the overflow water, to prevent splashing and prevent ponding of water around the well casing pipe. If a pump is installed in the well and the well stops flowing during pumping, a screen shall be installed on the overflow pipe.

NR 812.32(9)(d) (d) Complying installations. Illustrations of complying pump installations for flowing wells are shown in Figures 4 to 6 of ch. NR 812 Appendix.

NR 812.32 History History: Cr. Register, January, 1991, No. 421, eff. 2-1-91; am. (2) (a) 1. and 5., (6) (b) and Figure 32, renum. (4) (b), (6) (c), (7) and (8) to be (4) (b) 1., (7) to (9) and am. (7), (9) (c) 2. and 3., cr. (1) (a) 6., (d) and (4) (b) 2., Register, September, 1994, No. 465, eff. 10-1-94; correction in (4) (b) 1. c. made under s. 13.93 (2m) (b) 7., Stats., Register, May, 2000, No. 533; correction in (4) (b) 1. c. made under s. 13.92 (4) (b) 7., Stats., Register December 2011 No. 672; reprinted to reinsert omitted text in (4) Register January 2012 No. 67; CR 13-099: am. (1) (a) (intro.), cr. (1) (e), (f), am. (2) (b), cr. (4) (c), (d), am. (5) (b) 3. b., (6) (b), (9) (c) 3., cr. (9) (d) Register September 2014 No. 705, eff. 10-1-14; correction in (9) (d) title made under s. 13.92 (4) (b) 2., Stats., Register September 2014 No. 705; CR 18-095: am. (1) (a) 2., (c), (2) (a) 1., 3., r. (2) (a) 5., am. (2) (b), (3), (5) (b) 2. a. to d., (6) (a), (7), (9) (d) Register June 2020 No. 774, eff. 7-1-20; correction in (1) (a) 1. to 4., (c) made under s. 35.17, Stats., Register June 2020 No. 774.

NR 812.33 NR 812.33 Water storage vessels. The department recommends that pressure tanks be sufficiently sized to provide the minimum pump run time recommended by the pump manufacturer.

NR 812.33 Note Note: Community water systems regulated under ch. NR 811 are required to have a gross pressure tank volume of 10 times the pump capacity.

NR 812.33(1) (1) Pressure tanks.

NR 812.33(1)(a) (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:

NR 812.33(1)(a)1. 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. 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 approved pitless units 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.

NR 812.33 Note Note: The department recommends that a surface air check kit be installed for a buried pressure tank to check, maintain and adjust the air pressure pre-charge of the tank. Also, in uncontaminated soil areas, pipe and pipe connections to the tank should be made with flexible pipe and fittings meeting the requirements of s. NR 812.28 to minimize strain or pressure on the tank or the tank fittings.

NR 812.33(1)(a)2. 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:

NR 812.33(1)(a)2.a. a. If the tank is buried, all electrical controls extended to at least above ground grade.

NR 812.33(1)(a)2.b. 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.

NR 812.33(1)(a)2.c. c. An air compressor or other suitable means to add air to the tank.

NR 812.33(1)(a)2.d. 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.

NR 812.33 Note Note: The department recommends that the tank have bypass piping to allow operation of the system while the tank is being repaired or painted.

NR 812.33(1)(b) (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.

NR 812.33(2) (2) Nonpressure storage vessels. Nonpressure storage vessels, designed as part of a potable water supply system, may not be installed without approval from the department under s. NR 812.09. Approval is required regardless of whether or not there is a free-air gap in the water inlet line upstream of the vessel. Vessel approval is based on methods of construction and sanitary provisions. The installation of a surge tank is exempt from this approval requirement.

NR 812.33(2)(a) (a) Surge tanks. Surge tanks shall meet the requirements for pressure tanks described in s. NR 812.33 (1).

NR 812.33(2)(b) (b) Reservoirs and elevated storage tanks. A reservoir may be constructed to store water if it is constructed above the groundwater level and in accordance with this paragraph and Figure 7 of ch. NR 812 Appendix.

NR 812.33(2)(b)1. 1. ‘General construction specifications.’

NR 812.33(2)(b)1.a. a. Gravity supply pipes shall be located entirely above grade and shall be conducted to the reservoir through the roof or through the curbing for the manhole. The overflow pipe described in subd. 1. b. may be installed at such a level to provide a free-air gap. Buried supply pipe shall be maintained under a continuous pressure head which is greater than the ground surface elevation.

NR 812.33 Note Note: The department recommends that trees and shrubs not be planted within 25 feet of a reservoir.

NR 812.33(2)(b)1.b. b. An exposed overflow pipe shall be located just under the roof of the reservoir or outside the elevated storage tank and shall extend at least 8 feet away. The overflow pipe shall terminate with a downturned, screened elbow located at least 12 inches above ground grade. The pipe shall discharge onto a splash plate and have sufficient diameter to permit wasting water at a rate in excess of the inflow from the water source.

NR 812.33(2)(b)2. 2. ‘Steel construction specifications.’ Steel reservoirs or elevated storage tanks shall meet the requirements of AWWA D100-84 for welded construction or AWWA D103-80 for bolted construction.

NR 812.33(2)(b)3. 3. ‘Access.’ Water storage structures shall be designed with convenient access for cleaning and maintenance.

NR 812.33(2)(b)4. 4. ‘Concrete construction specifications.’ Reservoirs constructed of concrete shall meet the following specifications:

NR 812.33(2)(b)4.a. a. The supply pipe and overflow pipe shall extend through the structure.

NR 812.33(2)(b)4.b. b. An impervious flexible water stop strip for wall construction joint and a reservoir drain facility shall be installed before the concrete is poured.

NR 812.33(2)(b)4.c. c. 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 having a keyway or a flexible water stop strip for a construction joint with the walls.