(A) SWM plans for redevelopment shall provide ESD to the MEP consistent with the Design Manual and the Supplement. Overbank flood protection volume requirements do not apply unless required by the county in uncommon situations such as historic flooding, or extreme erosion where more stormwater control than the minimum required may be necessary.
(B) If the runoff from a proposed redevelopment site drains into a publically or privately owned regional SWM facility that provides full quality and quantity management, the developer may contribute their portion of the actual cost for the design/construction/repair/maintenance of the regional facility based on the per acre cost of the impervious acreage draining to the facility in lieu of onsite SWM measures. Adequate pretreatment, runoff capture, and stable conveyance to the regional facility must be provided.
(C) All redevelopment project designs shall reduce those existing site impervious areas within the limit of disturbance (LOD) built in accordance with an approved site plan by at least 50% below conditions existing on the date of the most recent county geographic information system orthophotography or as depicted on the original approved site plan. Where site conditions prevent the reduction of impervious area, then SWM practices shall implement ESD to the MEP for at least 50% of the site’s impervious area. When a combination of impervious area reduction and ESD is used, the combined reduced and treated area shall equal no less than 50% of the site’s impervious area within the LOD. Where existing site impervious areas were constructed after July 1, 1984, without an approved SWM plan, SWM shall be provided in accordance with § 151.035 for all impervious surfaces on the parcel.
(D) Alternative SWM measures may be used to meet the requirements in division (C) above if the owner or developer satisfactorily demonstrates to the county that impervious area reduction has been maximized and ESD has been implemented to the MEP. Alternative stormwater management measures include but are not limited to:
(1) An on site structural BMP;
(2) An off site structural BMP to provide water quality treatment for an impervious area equal to or greater than 70% of the existing impervious area;
(3) A combination of impervious area reduction, ESD implementation, and an on site structural BMP for an area equal to or greater than 50% of the existing site impervious area within the LOD; or
(4) A combination of impervious area reduction, ESD implementation and an off site structural BMP for an area equal to or greater than 70% of the existing site impervious area within the LOD.
(E) The county policies for providing stormwater runoff treatment for redevelopment projects if it is proven to the county’s satisfaction that the requirements of divisions (A), (B), (C) and (D) above cannot be met are as follows:
(1) Retrofitting of existing on site or off site BMPs that provide inadequate stormwater treatment for the impervious areas draining to them, identified by the county within the eight digit drainage basin of the project, to bring them up to current standards in accordance with the Design Manual and the Supplement. The retrofitted facilities must treat drainage from impervious areas that require additional treatment greater than that required for all site imperviousness within the LOD; or
(2) Fees paid into the Stormwater Management Fund established in § 151.067 for the exclusive purpose of providing management of stormwater. The fees shall be the estimated cost of constructing adequate onsite ESD and/or structural SWM practices as estimated by the design engineer or surveyor with concurrence by the County.
(2004 Code, § 191-8) (Ord. 01-12, passed 9-27-2001; Ord. 04-07, passed 4-1-2004; Ord. 2010-05, passed 4-29-2010; Ord. 2018-10, passed 11-29-2018)