(A) The development shall have an overland flow path at the downstream limit of the property that will pass the base flood flow without increasing damage to structures or property. Overland flow paths internal to the site shall be considered as part of the major stormwater system and shall be designed for conveyance of the base flood (critical duration) and shall be a minimum of one cfs per tributary acre without damage to structures. If the storm sewer pipe and inlet sized for the base flood can be constructed in lieu of providing an overland flow path as a part of the major drainage system, then the overland flow path shall be considered an emergency overland flow path and it shall not be considered a part of the major stormwater system but must still meet the protection of buildings criteria in § 160.018.
(B) For all overland flow routes, whether a part of the major drainage system or an emergency overland flow route, the water surface elevation for determining the FPE (flood protection elevation) shall be calculated assuming that the storm sewers are inoperable.
(C) Structures of any kind, including fences, shall not be permitted in overland flow paths draining more than 20 acres, unless the structures are otherwise permissible and certified by a professional engineer or professional landscape architect that the proposed structure will not cause any adverse upstream impacts as a result of blocking or impeding the flow of stormwater. A fence, if permitted, shall conform to the village's fence ordinance provisions for fences located in drainage easements as applicable.
(Ord. 06-0383, passed 3-15-06)