A storage trench is a subsurface rectangular bed cut into the street or sidewalk. The storage areas are designed to infiltrate stormwater or slow its flow into the sewer system.
Infiltration/storage trenches are filled with stone, plastic crates, or precast modular systems designed to either infiltrate stormwater or slow its flow into the sewer system. As water enters the trench (usually through a green inlet or pervious pavement), it fills the voids within the system, seeps to the bottom of the trench and soaks into the soil beneath. Excess water that does not infiltrate into the soil is slowly released into the sewer system at a controlled rate. Infiltration/storage trenches can be located under sidewalks, parking lots, lawns, or other pervious and impervious recreational areas (basketball courts, athletic fields, etc.) They can be connected to other stormwater tools types, such as bump-outs, to receive stormwater overflow from these systems. Some infiltration/storage trenches have very large drainage areas that collect runoff through an intricate series of inlets.