When the bottom of a drinking water storage tank will be placed below the normal ground surface, it shall be placed above the local ground water table.(3) Covered Roof.
When the roof of a drinking water storage tank will be covered by earth, the roof shall be sloped to drain toward the outside edge of the tank.
R309-545-9. Tank Roof and Sidewalls.
(1) Protection From Contamination.
All drinking water storage tanks shall have suitable watertight roofs and sidewalls that shall also exclude birds, animals, insects, and excessive dust.
(2) Openings.
Openings in the roof and sidewalls shall be kept to a minimum and shall comply with the following:
(a) Any pipes running through the roof or sidewall of a metal drinking water storage tank shall be welded, or properly gasketed. In new concrete tanks, these pipes shall be connected to standard wall castings with seepage rings that have been poured in place. Vent pipes, in addition to seepage rings, shall have raised concrete curbs that direct water away from the vent pipe and are formed as a single pour with the roof deck. Roof drains or any other pipes, which may contain water of lesser quality than drinking water, shall not penetrate the roof, walls, or floor of a drinking water storage tank.
(b) Openings in a storage tank roof or top, designated to accommodate control apparatus or pump columns, shall be welded, gasketed, or curbed and sleeved as above, and shall have additional proper shielding to prevent vandalism.
(3) Adjacent Compartments.
Drinking water shall not be stored or conveyed in a compartment adjacent to wastewater when the two compartments are separated by a single wall.
(4) Roof Drainage.
The roof of all storage tanks shall be designed for drainage to eliminate water ponding. Parapets, or similar structures, which would tend to hold water and snow, shall not be allowed/permitted unless adequate waterproofing and drainage are provided. Downspout or roof drain pipes shall not enter or pass through the tank.
R309-545-10. Internal Features.
The following shall apply to internal features of drinking water storage tanks:
(1) Drains.
(a) A means shall be provided for the draining of drinking water storage tanks.
(b) Where possible, the drain shall be separate from the outlet pipeline. If a tank drain line is provided, it shall be sloped for complete drainage.
(c) The drain shall not discharge to a sanitary sewer.
(d) If local authority allows discharge to a storm drain, the drain discharge shall have a physical clearance of at least 12 inches between the discharge end of the pipe and the overflow rim of the receiving basin.
(2) Internal Catwalks.
Internal catwalks, if provided and located over the drinking water, shall have a solid floor with raised edges. The edges and floor shall be designed so that shoe scrapings or dirt will not fall into the drinking water.
(3) Inlet and Outlet.
(a) To minimize potential sediment in the flow from the tank, the outlet pipes from all tanks shall be located in a manner to provide a silt trap prior to discharge into the distribution system.
(b) Inlet and outlet pipes shall be configured to provide mixing and circulation.
(4) Tank Floor.
The floor of the storage tank shall be sloped to permit complete drainage of the structure.
R309-545-11. Internal Surfaces and Coatings.
(1) ANSI/NSF Standard 61 Certification.
All interior surfaces and coatings shall comply with ANSI/NSF Standard 61 or other standards approved by the Director. This requirement applies to any pipes and fittings, protective materials (e.g., paints, coatings, concrete admixtures, concrete release agents, or concrete sealers), joining and sealing materials (e.g., adhesives, caulks, gaskets, primers and sealants) and mechanical devices (e.g., electrical wire, switches, sensors, valves, or submersible pumps) that may come into contact with the drinking water.
(2) Curing Procedures and Volatile Organic Compounds.
(a) Proper curing procedures shall be followed per manufacturer's directions, including curing time, temperature, and forced air ventilation. Drinking water shall not be introduced into the tank until proper curing has occurred.
(b) It shall be the responsibility of the water system to assure that no tastes, odors, toxins, or contaminantsthat result in MCL exceedances, are imparted to the water as a result of tank coating or repair.
(c) Prior to placing a drinking water storage tank in service, cleaning, disinfection, and flushing procedures shall be completed.
(d) Prior to placing a drinking water storage tank in service, an analysis for volatile organic compounds from water contained therein may be required to verify compliance with drinking water maximum contaminant levels.
