(A) Minimum control requirements.
(1) All stormwater management practices will be designed so that the specific storm frequency storage volumes (such as recharge, water quality, channel protection, 10-year or 100-year) as identified in the Reference Manuals or other municipal ordinances are met, unless the MS4 Coordinator grants the applicant a waiver or the applicant is exempt from such requirements.
(2) In addition, if hydrologic or topographic conditions warrant greater control than that provided by the minimum control requirements, the MS4 Coordinator 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. Among the factors that should be considered:
(a) Topography;
(b) Maximum drainage area;
(c) Depth to water table;
(d) Soils;
(e) Slopes;
(f) Terrain; and
(g) Location in relation to environmentally sensitive features or ultra-urban areas.
(2) Applicants shall consult the Reference Manuals referred to in § 52.05 and other ordinances for guidance on the factors that determine site design feasibility when selecting a stormwater management practice.
(C) Conveyance issues. 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:
(1) Maximizing of flow paths from inflow points to outflow points;
(2) Protection of inlet and outfall structures;
(3) Elimination of erosive flow velocities;
(4) Providing of under-drain systems, where applicable.
(D) Treatment/geometry conditions. All stormwater management practices shall be designed to capture and treat stormwater runoff according to the specifications outlined in the Reference Manuals and other ordinances. These specifications will designate the water quantity and quality treatment criteria that apply to an approved stormwater management practice.
(E) Landscaping plan requirements. All stormwater management practices must have a landscaping plan detailing both the vegetation and the manager in which and by whom this vegetation shall be maintained.
(F) 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.
(G) Non-structural stormwater practices. The use of non-structural stormwater treatment practices is encouraged in order to minimize the reliance on structural practices. Credit in the form of reductions in the amount of stormwater that must be managed can be earned through the use of non-structural practices that reduce the generation of stormwater from the site. These non-structural practices are explained in detail in the Reference Manuals referred to in § 52.05 and/or by the MS4 Coordinator. Applicants wishing to obtain credit for use of non-structural practices must ensure that these practices are documented and remain unaltered by subsequent property owners.
(Ord. 2007-05, passed 4-17-07)