Step Pool Stormwater Conveyance Systems

Step Pool Stormwater Conveyance Systems (SPSCs) are open-channel conveyance structures that convert, through attenuation ponds and a sand seepage filter, surface storm flow to shallow groundwater flow.

About Step Pool Conveyance Systems

Step Pool Conveyance Systems safely convey, attenuate, and treat the quality of storm flow. These structures utilize a series of constructed shallow aquatic pools, riffle grade control, native vegetation, and an underlying sand/woodchip mix filter bed media. The physical characteristics of the SPSC channel are best characterized by the Rosgen A or B stream classification types, where “bedform occurs as a step/pool, a cascading channel which often stores large amounts of sediment in the pools associated with debris dams” (Rosgen, 1996). 

The pretreatment, recharge, and water quality sizing criteria presented in these guidelines follow closely the State of Maryland’s criteria for a typical stormwater filtering device. These structures feature surface/subsurface runoff storage seams and an energy dissipation design that is aimed at attenuating the flow to a desired level through energy and hydraulic power equivalency principles.