The drainage system is designed to collect stormwater runoff from the roadway surface and right-of-way and surrounding land, convey it along and through the right-of-way, and discharge it to an adequate receiving body without causing adverse on- or off-site impacts.
Stormwater collection systems must be designed to provide adequate surface drainage. Traffic, passengers and goods safety is intimately related to surface drainage. Rapid removal of stormwater from the catchment minimizes the conditions which can result in the hazards of hydroplaning.
The objective of stormwater conveyance systems (storm drain piping, ditches and channels, pumps, etc.) is to provide an efficient mechanism for conveying design flows from inlet locations to the discharge point without surcharging inlets or otherwise causing surface flooding.
Erosion potential must also be considered in the design of open channels or ditches used for stormwater conveyance.
The design of appropriate discharge facilities for stormwater systems include consideration of stormwater quantity and quality. Local and/or State regulations often control the allowable quantity and quality of stormwater discharges. To meet these regulatory requirements, storm drainage systems will also require other best management practices for the control of discharge quantity and quality.
Best Management Practices (BMP’s) are nonstructural or low structurally intensive alternatives for the control of urban runoff.