(A) Surface flow. Surface swales/ditches described in § 158.072, shall be encouraged for use as designed in accordance with the requirements of this chapter. Natural swales and depressional storage areas shall be incorporated into storm water facilities design wherever practicable. Swales and ditches, together with any underground storm sewer system, shall provide an adequate outfall for runoff from the 100-year frequency 24-hour duration rainstorm. In areas where swales/ditches can not be provided, the underground storm sewer system shall be designed for the 100-year storm condition. Where allowed by the Village Engineer, storm sewers may be constructed to drain the development and any contiguous drainage areas. The subdivider shall submit to the Village Engineer two copies of the storm drainage computations.
(B) Storm water detention. Storm detention is required and subject to the review of the Village Engineer. A detention pond shall have high-water level based on a 100-year design storm and shall have an outlet which allows runoff no greater than that for the land in its natural state prior to development. Previously developed sites not providing storm water detention must, when undergoing redevelopment and/or additions, provide detention meeting the requirements of this chapter. Detention to be provided shall be for the entire site evaluated in its natural state and shall be constructed prior to all other improvements. This shall include mass grading and all necessary erosion control measures.
(C) Drainage basin divides. The design of storm water drainage systems shall not result in the interbasin transfer of drainage, unless no reasonable alternative exists and there is no legal restraint preventing such transfer.
(D) Sump pump connections. All new subdivisions will supply a four-inch service connection for each unit or lot in said subdivision. Upon construction the builder will connect the house sump to the storm water connection.
(E) Lot grading. The location and top of foundation elevation for all proposed structures shall be shown on the engineering drawings. Generally, the top of foundation of any structure must be constructed at least 18 inches above the centerline (or back of curbs) of the abutting street. Where foundations are lower than the street centerline, or in the case of depressed driveways, alternate means of surface drainage diversion must be shown to avoid structure flooding. Sufficient finished grade elevations must be shown on the drawings to ensure positive drainage away from each structure.
(Ord. 04-02, § 158.008, passed 4-5-04)