(A) Reference. Normal flow demands for design shall be calculated on the basis of full ultimate development as known, or projected. The average daily flow for domestic use shall be calculated at the minimum rate of 100 gallons per day per capita, with 3.5 persons per single-family residence, and 2.5 persons per multi-family or mobile home dwelling unit. Maximum day demand to be used for design shall be 0.9 gallons per minute (GPM) per single-family residence and 0.7 GPM per dwelling unit for each multi-family or mobile home unit. Flow demands for commercial, industrial, or other special developments shall be established from existing records or by estimated projections, using the best available data.
(B) Water systems. Water distribution systems and/or water main extensions shall be designed and constructed in accordance with the fire protection requirements of the Insurance Services Office (National Board of Fire Underwriters), as stated in their publication "Guide for the Determination of Required Fire Flows", if not in conflict with the following:
(1) Single-family. Fire flows in single-family residential areas shall provide 500 gpm at a 20 psi residual pressure.
(2) Commercial and industrial. Fire flows in commercial, institutional, industrial areas and apartment or multi-unit complexes shall provide 1,250 gpm at a 20 psi residual pressure.
(3) Fire hydrants. Distance from or spacing for hydrants located within areas or development containing one or two family dwelling units shall not exceed 1000 feet (measured along the street) and shall be connected to water mains of six inches minimum size, which are of satisfactory loop design. Minimum distance and size requirements for areas or development containing multi-family dwelling units, commercial, institutional or industrial uses are 500 feet and eight inches, respectively (measured along the street). Connection to dead end stubs are acceptable, provided that said stubbed water main is not less than eight inches. The city may require larger diameter water mains for long lines that are not connected to other mains at intervals close enough for proper mutual support, or as may be required to provide the fire flow and residual pressures specified.
(4) System size computation. The minimum design for water distribution systems shall provide for at least 100% of the combined maximum day-demand rate and required fire flow for said rate, with special provisions for peak flows in excess thereof. The allowable minimum service pressure under said design condition shall not be less than 20 pounds per square inch. Design computation shall be by the "Hardy Cross" procedure, or other applicable methods, as dictated by the system configuration. Design flows and method of computation shall be subject to review and approval by the city.
(5) Valve locations. Valves shall be provided for all branch connections, loop ends, fire hydrant stubs, or other locations, as required to provide an operable, easily maintained, and repaired water distribution system. Valves are to be placed so that the maximum allowable length of water main required to be shutdown for repair work shall be 500 feet in commercial, industrial or multi-family residential areas, or 1,000 feet in other areas.
(Ord. 348, passed 12-3-87; Am. Ord. 1056, passed 5-2-02) Penalty, see § 77