NR 811.64(6)(a)(a) Groundwater facilities. If the water system design is such that all water passes through one ground reservoir, there shall be bypass piping from the well pumps to the high lift pumps to allow the reservoir to be taken out of service for cleaning and maintenance. The department may waive this requirement if the well pumps can provide sufficient volume and pressure directly to the distribution system, if the well pumps and high lift pumps are greatly different in capacity, or if the reservoir is divided into multiple cells which can be independently removed from service. If CT is required, the department will approve bypass piping around reservoirs only if the required minimum CT can be met with the reservoir chamber or chambers out of service. NR 811.64(6)(b)(b) Surface water facilities. If the water treatment plant design is such that all water passes through one ground reservoir, bypass piping or multiple cells shall be installed to allow the reservoir to be totally or partially taken out of service for cleaning and maintenance. The design shall provide for maintaining the required minimum CT while the reservoir is totally or partially out of service. NR 811.64(7)(7) Access. Water storage structures shall be designed with reasonably convenient access for cleaning and maintenance. Manholes installed above the waterline shall meet the following requirements: NR 811.64(7)(a)(a) Elevated storage structures and reservoirs covered by inhabitable structures. Manholes on elevated tanks, standpipes and reservoirs covered by inhabitable structures shall be framed a minimum of 4 inches above the surface of the roof. Manhole openings shall be fitted with a solid watertight cover. Manhole covers for elevated tanks shall overlap the framed opening and extend down around the frame a minimum of 2 inches. A compressible gasket shall be provided so that when the cover is closed it will provide a water tight seal around the manhole opening. NR 811.64(7)(b)(b) Ground storage structures. On ground level structures, manholes shall be elevated no less than 24 inches above the top or covering sod. Manhole openings shall be fitted with a solid watertight cover that overlaps the framed opening and extends down around the frame a minimum of 2 inches. A compressible gasket shall be provided so that when the cover is closed it will provide a water tight seal around the manhole opening. NR 811.64(7)(c)(c) Locks. Overlapping interior and exterior manhole covers shall be locked at all times except when being used by authorized personnel. NR 811.64(7)(d)(d) Other openings. All other manholes, openings, or access ways shall be provided with watertight, bolted, and gasketed covers. NR 811.64(8)(8) Vents. Water storage structures shall be vented to the atmosphere. Vent installations shall meet the following requirements: NR 811.64(8)(a)2.2. Open construction between the sidewalls and the roof to act as a vent is not allowed. NR 811.64(8)(b)1.1. Prevent the entrance of surface water, rain and snow as applicable. NR 811.64(8)(b)3.3. Exclude insects and dust to the extent this can be done while providing effective venting. NR 811.64(8)(c)(c) Elevated tanks and standpipes. Vents installed on elevated tanks and standpipes shall terminate with a mushroom cap constructed with the opening at least 4 inches above the roof and shall be provided with a 4-mesh outer screen and 4- to 24-mesh inner screen constructed of corrosion resistant material installed within the pipe at a location protected from the environment. The mushroom cap shall be provided with an automatically resetting pressure-vacuum relief frost-proof mechanism. The skirted sides of mushroom caps shall totally cover any screens when viewing the cap from the side. NR 811.64(8)(d)(d) Ground level structures. Vents installed on ground level structures shall terminate in a U-bend or mushroom cap constructed with the opening 24 to 36 inches above the roof or sod and covered with 24-mesh corrosion resistant screen installed within the pipe or cap at a location least susceptible to vandalism. The skirted sides of mushroom caps shall totally cover any screens when viewing the cap from the side. NR 811.64(8)(e)(e) Size. Vents shall be sized to allow an air flow consistent with maximum water inflow and outflow rates. NR 811.64(8)(f)1.1. Vent pipes shall be constructed of ductile iron, steel, or stainless steel pipe. NR 811.64(8)(f)2.2. Mushroom caps shall be constructed of steel, stainless steel, or aluminum. NR 811.64(8)(f)4.4. Inner pallet screens of frost-proof mushroom cap vents shall be constructed of corrosion resistant material. NR 811.64(9)(9) Silt stop. The discharge pipes from all water storage structures shall be located in a manner that will prevent the flow of sediment into the distribution system. Removable silt stops shall be required where feasible. NR 811.64(10)(10) Roof and sidewalls. The roof and sidewalls of all storage structures shall be constructed to meet the following requirements: NR 811.64(10)(a)(a) Watertight construction. The roof and sidewalls of all structures shall be watertight with no openings except properly constructed vents, manholes, overflows, risers, drains, pump mountings, control ports, or piping for inflow and outflow. NR 811.64(10)(b)(b) Sealed openings. Any pipes running through the roof, floor or sidewall of a finished water storage structure shall be sealed watertight. Openings for metal tanks shall be welded or properly gasketed. Pipes running through openings in a concrete structure shall be connected to a standard wall pipe or run through a wall sleeve which were poured in place during the formation of the structure. These wall pipes and wall sleeves shall be metal and have seepage rings embedded in the concrete. Pipes running through a wall sleeve shall be provided with a department approved watertight seal installed between the pipe and the wall sleeve. NR 811.64(10)(c)(c) Roof curbing. Openings in a storage structure roof or top, designed to accommodate control apparatus, pump columns and other equipment, shall be provided with minimum 4-inch high curbing and sleeved with proper additional flashing to prevent the access of surface or floor drainage water to the structure.