(A) General comments. This section describes the city’s policies concerning hydrologic analysis procedures to be used in the city for the planning and design of drainage and flood control facilities and the preparation of accompanying drainage reports. This section contains recommended procedures, equations, data and basic assumptions which the planner or designer is generally required to use. If a situation is encountered in which the use of other methods or data in addition to or instead of these are believed to be more appropriate, then the city engineer should be consulted and advance approval must be received before using them. When methods or data not described in this Chapter are used, the drainage report must include enough information to enable the city engineer to fully evaluate the applicability of the methods and data.
(B) Basis of design.
(1) The Drainage Design Manual for Maricopa County, Volume I, Hydrology, Section 3, Rational Method, shall be used to determine peak discharges and volumes for design purposes for small, uniform, regularly shaped watersheds less than 160 acres.
(2) The Corps of Engineers’ HEC-1 or HEC-HMS computer modeling is required for small watersheds that are non-uniform, irregular in shape, when routing of flows are necessary, or for areas larger than 160 acres.
(C) Study requirements. A hydrology study shall be performed for each development within the city. The study shall define the overall and sub-drainage areas. It shall also determine appropriate hydrologic data for the following:
(1) Off-project areas. The drainage flows for each off-project drainage area tributary to the project shall be computed and submitted in summary form. These off-site flows will be based on the City of Apache Junction Stormwater Master Plan dated January 2002 (adopted in Apache Junction City Code Vol. II, § 10-4-3) or from consultant’s computations where the Master Plan does not cover.
(2) Project sub-basins. The project shall be divided into sub-basins tributary to appropriate design points. The pertinent hydrologic data shall be computed for each and submitted in summary form.
(3) Appropriate design points. APPROPRIATE DESIGN POINTS are those points wherein the peak flow rates, or other pertinent data, are needed to determine flow capacity requirements, inflow-outflow relationships and the like. These points would include but not necessarily be limited to the following: inflow-outflow points of retention/detention basins, up and/or downstream ends of culverts; intake points for storm drains (e.g., inlets, catch basins, scuppers and the like); points immediately upstream and downstream of channel junctions and/or street intersections; others as may be necessary to give a complete hydrologic picture and allow a thorough hydraulic evaluation and/or design of the drainage system.
(Ord. passed - - )