Infiltration practices provide temporary surface and/or subsurface storage, allowing infiltration of runoff into soils. In practice, an excavated trench is usually filled with gravel or stone media, where runoff is stored in pore spaces or voids between the stones (see figure 1). These systems can reduce significant quantities of stormwater by enhancing infiltration, as well as provide filtering and adsorption of pollutants within the stone media and soils. Infiltration practices are part of a group of stormwater treatment practices, also known as best management practices (BMPs)