The city shall establish and maintain a master plan for a stormwater system designed to handle the stormwater runoff. The master plan shall be adopted by approval of the City Council and shall be effective as of the date of its adoption. The master plan shall provide or be accompanied by maps or other descriptive material showing, at a minimum, the following:
(a) An inventory of the stormwater facilities plus the extent and area of each watershed tributary to the main drainage channels in the city;
(b) The street storm sewers and other storm drains to be built; the basis of their design; the outfall, inlet and outlet locations; the receiving stream or channel and its high water elevation; and the functioning of the systems and facilities during high water conditions;
(c) The parts of the proposed street system where pavements are planned to be depressed sufficiently to convey or temporarily store overflow from storm sewers and runoff over the curb resulting from the heavier rainstorms and the outlets for such overflow;
(d) Streams and floodplains to be maintained, enlarged, altered, and eliminated; and new channels to be constructed, their locations, cross-sections and profiles;
(e) Culverts and bridges, drainage areas, and adequacy of waterway openings, including new culverts and bridges to be built, waterway openings and the basis of their design;
(f) Detention ponds and basins to be maintained, enlarged, and altered; and new ponds or basins to be built with dams, if any;
(g) The slope, type, and size of all sewers and other waterways;
(h) For all detention/retention basins, a tabulation of storage volumes with corresponding water surface elevations and of the basin outflow rates for those water surface elevations;
(i) For all detention/retention basins, design hydrographs of inflow and outflow for the design year under developed conditions and the calculated frequency peak flows from the site under natural and developed conditions;
(j) An examination of the need for reduction of pollution loads resulting from surface runoff where applicable, now or in the future; and
(k) Estimates of cost will be broken down in to two categories; those that are city responsibility and those that are private responsibility.
(Ord. 04-39, passed 9-23-2004)