Erosion control best management practices are required during all ground disturbing activity until permanent site ground covers are in place. A best management practice (BMP) is a physical, chemical, structural or managerial practice that prevents, reduces or treats contamination of water or which prevents or reduces soil erosion.
Stormwater control is a vital element to prevent erosion. The following stormwater BMPs describe methods to convey, divert, treat and otherwise control stormwater flow rates and volumes. Stormwater control BMP sizing can be complex, and runoff volumes and rates difficult to predict. It is recommended that a licensed design engineer be consulted on all stormwater designs.
Stormwater Control BMPs are:
- Interceptor Dikes and Swales
- Intercept and/or divert storm runoff from onsite and offsite drainage areas
- To convey runoff from above unprotected slopes or a disturbed site and direct it to a sediment trap, pond or other approved stabilized outlet
- Dikes and swales may be installed as a permanent site drainage control feature, while providing conveyance of temporary development flows
- Check Dams
- Reduce velocities in a ditch, dike or swale
- Provide sedimentation behind the dam for development site flows
- Should not be used as permanent installations unless sufficiently keyed into side slopes
- Pipe Slope Drain
- Pipe slope drains are temporary conduits, usually of flexible piping, that are joined from the top of a slope to the bottom of the slope t o contain and convey runoff without coming in contact with bare slope soils causing erosion
- Stormwater Barriers
Stormwater barriers are a group of portable materials including hay bales, foam triangles, plastic dams, rock sack berms and other materials meant to impound stormwater and sediment laden flows. These systems are many times manmade, can be modular and therefore replaced by sections, and have sediment-settling abilities. Some systems are designed to dissipate flows.
- Temporary impoundment of stormwater erosion laden flows
- Straw bales for emergency sediment flow diversion
- Sediment Traps and Ponds
- Control sediment laden flows leaving the site
- To collect and store sediment-eroded from exposed ground surfaces disturbed during site development
- Designers are encouraged to consider if ponds created to control sediment and other pollutants during site development could be used to manage post development stormwater runoff