A. Minimum control requirements. All stormwater management practices will be designed so that the specific storm frequency storage volumes (such as recharge, water quality, channel protection, ten year, one hundred year) as identified in the current stormwater design manual are met.
B. Site Design Feasibility. Stormwater BMP's for a site shall be chosen based on the physical conditions of the site. Among the factors that should be considered:
1. Topography.
2. Maximum Drainage Area.
3. Depth to Water Table.
4. Soils.
5. Slopes.
6. Terrain.
7. Head.
8. Location in relation to environmentally sensitive features or ultra-urban areas.
9. Applicants shall consult the stormwater design manual 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 allow for the maximum removal of pollutants and reduction in the volume and rate of discharge. This shall include, but not be limited to:
1. Maximizing flow paths from inflow points to outflow points,
2. Protection of inlet and outfall structures,
3. Elimination of erosive flow velocities, and
4. Providing underdrain systems, where applicable.
The Stormwater Design Manual 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 the stormwater design Stormwater Design Manual.
E. Treatment/Geometry Conditions
All stormwater management practices shall be designed to capture and treat stormwater runoff according to the specifications outlined in the Storwater Design Manual. These specifications will designate the water quantity and quality treatment criteria that apply to an approved stormwater management practice.
F. Vegetation plans required. All stormwater management practices must have a plan detailing the type of vegetation to be planted in the practice area, how will it be maintained, and who will manage arid maintain this vegetation. This plan must be prepared by a registered landscape architect.
G. Maintenance agreements. All stormwater management practices shall have an enforceable operation and maintenance agreement to ensure the system functions as designed. This agreement will include all maintenance easements required to access and inspect the stormwater management practices and access to perform routine maintenance as necessary to ensure proper functioning of the practice.
H. Non-structural stormwater practices. The use of non-structural stormwater treatment practices is encouraged in order to minimize the reliance on structural practices. Credit can be earned, in the form of reductions, when nonstructural management practices are utilized to reduce the stormwater runoff generated from the site because of the proposed construction activity. Non-structural practices are explained in detail in the current design manual and applicants wishing to obtain credit for use of nonstructural practices must ensure that these management practices are documented, remain unaltered, and binding to subsequent property owners.
(Ord. 08-29, 2008)