All storm drainage design shall be planned and executed so as to preserve natural topographic features and vegetative cover, to minimize change to existing topography and to preserve natural drainage systems.
(A) Where an adequate public storm sewer is available at the plat boundary, the sub-divider shall construct a storm sewer system and connect with such storm sewer line. If such a storm sewer system is not accessible, natural drainage channels with easements of at least 30 feet in width shall be provided, as determined by the City Manager and approved by the Planning Commission. Storm drainage from lots, including drain tile around basements, shall not be permitted to discharge into any sanitary sewer facility, but shall connect to an adequate drainage outlet.
(B) The sub-divider shall construct all necessary facilities including underground pipe, inlets, catch basins or open drainage ditches, as determined by the City Manager, to provide for the adequate disposal of subsurface and surface water and maintenance of natural drainage courses. The best available technology shall be used to minimize off-site storm water runoff, increase on-site filtration, simulate natural drainage systems and minimize off-site discharge of pollutants to ground and surface water. Best available technology may include measures such as retention basins, recharge trenches, porous paving and piping, contour terraces and swales. Storm water management shall follow the standards established in Rainwater and Land Development, Second Edition, 1996, ODNR, or any later version that is published as an update. Subdivision development shall not increase the rate of runoff and an increase in the volume of runoff shall require a reduction in the rate of runoff. NRCS TR-55, or other suitable engineering method, shall be used to determine flow rate. Manning’s equation, or other suitable engineering method, shall be used to determine velocity.
(C) When necessary, outlet ditches of closed sewers of an approved type and size shall be required as part of the construction. If the same is across private property, rights-of-way or easements shall be obtained by the sub-divider for construction and future maintenance. These rights-of-way or easements shall be shown on the construction plans. The channel downstream of the subdivision shall be improved adequately by the sub-divider to convey the storm runoff from the subdivision and across the adjacent property owner so that damages from flooding are minimized. Whenever possible, post-development drainage patterns shall be the same as pre-development drainage patterns.
(D) The sub-divider shall guard against the creation or continuation of swampy areas or stagnant pools, unless they are a component of a designed wetlands open space. The City Manager may require fill, swale and/or channel improvements in order to forestall such problems.
(Prior Code, § 23.06.05) Penalty, see § 151.999