What is the minimum required velocity for stormwater piping?

The minimum required velocity for stormwater piping is set to ensure that sediment and debris are effectively transported through the system without causing blockages or settling within the pipes. A velocity of 3 feet per second (fps) is generally recognized as appropriate for maintaining the necessary flow characteristics in stormwater drainage systems. This velocity helps to minimize the risk of sediment deposition that can lead to clogging, thus ensuring the system operates efficiently during storm events.

Furthermore, if the velocity is too low, such as at 1 fps or 2 fps, it may not provide sufficient force to carry debris along, leading to potential accumulation and maintenance issues. Conversely, if the velocity is excessively high (like 4 fps), it could increase wear and tear on the piping materials and might create other hydraulic issues, such as excessive turbulence or air entrainment. Thus, the specified minimum velocity is balanced to promote effective drainage while safeguarding the integrity of the system.