(A) Generally. Stormwater runoff from areas tributary to the property shall be considered in the design of the property’s drainage system. Whenever practicable, flows from upstream areas that are not to be detained should be routed around the basin being provided for the site being developed.
(B) Upstream areas not meeting ordinance requirements. When there are areas not meeting the storage and release rates of this chapter, tributary to the applicant’s property, regionalized detention on the applicant’s property shall may be explored by the applicant or the county. When it is deemed beneficial by the county or the applicant to explore such a design, the following steps shall be followed:
(2) Areas tributary to the applicant’s property, not meeting the storage and release rate requirements of this chapter, shall be identified.
(3) (a) Using the areas determined above plus the applicant’s property area, total storage needed for the combined properties shall be computed.
(b) Allowable release rates shall be computed using the combined property areas. Storage shall be computed as described in § 152.23. If tributary areas are not developed, a reasonable fully developed land cover, based on local zoning, shall be used for the purposes of computing storage.
(c) Once the necessary combined storage is computed, the village may choose to pay for over-sizing the applicant’s detention basin to accommodate the regional flows. The applicant’s responsibility will be limited to the storage for his or her property as computed above. If regional storage is selected by the village then the design produced in § 152.22 shall be implemented. If regional storage is rejected by the village, the applicant shall bypass all tributary area flows around the applicant’s basin whenever practicable. If the applicant roust route upstream flows through his or her basin and the upstream areas exceed one square mile in size, the applicant must meet the provision of § 152.23(K) for onstream basins.
(C) Upstream areas meeting ordinance requirements. When there are areas which meet the storage and release rate requirements of this chapter, tributary to the applicant’s property, the upstream flows shall be bypassed around the applicant’s detention basin if this is the only practicable alternative. Storage needed for the applicant’s property shall be computed as described in § 152.23. However, if the village decides to route tributary area flows through an applicant’s basin, the final design stormwater releases shall be based on the combined total of the applicant’s property plus tributary areas.
(Ord. passed 12-9-02)