Stormwater runoff both on-site and downstream will usually be affected by the development or redevelopment of property. Care must be taken in the design of stormwater infrastructure to minimize impacts, particularly during heavy rainfall events.
In addressing these impacts the designer should prepare plans for improvements that provide for safe and adequate conveyance of stormwater from higher elevations to lower elevations within the site. Furthermore, as stormwater leaves the site, adequate provisions must be in place to minimize adverse downstream impacts (erosion, etc.)
The developers of large projects are encouraged to provide for retention of stormwater on-site through the utilization of basins, storage pipes and other devices. Those projects for which the issuance of a Special Use Permit is necessary will generally be required to implement retention measures if downstream properties would be adversely affected.
Submitted plans for a project should be of sufficient detail to clearly indicate the existing topography, proposed grading and placement of all stormwater appurtenances such as swales, curbs, pipes, inlets, junction boxes, etc. Pertinent storm drainage calculations should also be submitted. These plans also serve as the basis for the application for an Erosion and Sedimentation Control permit if more than one acre of land is to be disturbed by the project.