(A) Minimum control requirements.
(1) All stormwater management practices will be designed so that the specific storm frequency storage volumes as identified in the Wayne County Stormwater Program are met, unless the City Engineer grants the applicant a waiver or the applicant is exempt from such requirements as outlined in §§ 52.057 and 52.062.
(2) In addition, if hydrologic or topographic conditions warrant greater control than that provided by the minimum control requirements, the City of Wyandotte reserves the right to impose any and all additional requirements deemed necessary to control the volume, timing, and rate of runoff.
(B) Site design feasibility.
(1) Stormwater management practices for a site shall be chosen based on the physical conditions of the site.
(2) Among the factors that should be considered:
(a) Topography;
(b) Maximum drainage area;
(c) Depth to water table;
(d) Soils;
(e) Slopes;
(f) Terrain;
(g) Head; and
(h) Location in relation to environmentally sensitive features or ultra-urban areas.
(3) Applicants shall consult the Wayne County Stormwater Program for guidance on the factors that determine site design feasibility when selecting a stormwater management practice.
(C) Conveyance issues.
(1) All stormwater management practices shall be designed to convey stormwater to allow for the maximum removal of pollutants and reduction in flow velocities. This shall include, but not be limited to:
(a) Maximizing of flow paths from inflow points to outflow points;
(b) Protection of inlet and outfall structures;
(c) Elimination of erosive flow velocities; and
(d) Providing of underdrain systems, where applicable.
(2) The Wayne County Stormwater Program shall provide detailed guidance on the requirements for conveyance for each of the approved stormwater management practices.
(D) Pretreatment requirements. Every stormwater treatment practice shall have an acceptable form of water quality pretreatment, in accordance with the pretreatment requirements found in Wayne County Stormwater Program. Certain stormwater treatment practices, as specified in the Wayne County Stormwater Program, are prohibited even with pretreatment, in the following circumstances:
(1) Stormwater is generated from highly contaminated source areas known as "hotspots."
(2) Stormwater is carried in a conveyance system that also carries contaminated, non- stormwater discharges.
(3) Stormwater is being managed in a designated groundwater recharge area.
(4) Certain geologic conditions exist (e.g., karst) that prohibit the proper pretreatment of stormwater.
(E) Treatment/geometry conditions. All stormwater management practices shall be designed to capture and treat stormwater runoff according to the specifications outlined in the Wayne County Stormwater Standards Manual. These specifications will designate the water quantity and quality treatment criteria that apply to an approved stormwater management practice.
(F) Landscaping plans required. All stormwater management practices must have a landscaping plan detailing both the vegetation to be in the plan and how and who will manage and maintain this vegetation. This plan must be prepared by a registered landscape architect or soil conservation professional.
(G) Maintenance agreements. All stormwater treatment practices shall have an enforceable operation and maintenance agreement to ensure the system functions as designed. This agreement will include any and all maintenance easements required to access and inspect the stormwater treatment practices, and to perform routine maintenance as necessary to ensure proper functioning of the stormwater treatment practice. In addition, a legally binding covenant specifying the parties responsible for the proper maintenance of all stormwater treatment practices shall be secured prior to issuance of any permits for land disturbance activities.
(Ord. 1521, passed 2-7-2022)