Abstract: In a system for dispersing stormwaters beneath the earth surface, a pair of arch shaped corrugated molded plastic chambers lie parallel each to the other upon a bed of gravel and are covered with soil. A bridge cover spans the space between the sidewalls of the adjacent chambers, to keep soil above from entering. Abutting base flanges establish the chamber spacing which fits the bridge cover and also protect the gravel at the bottom of the space from erosion. Stormwater is delivered to the space, to then flow through sidewall perforations into the chambers' interiors where it is stored and gradually dispersed into the earth. Debris settles in the pocket at the bottom of the space and is removed by a perforated pipe lying in the space. Chambers have high aspect ratios, of 0.8 to 1 or more, and steep sidewall angles, of less than 15 degrees.

Abstract: A molded plastic leaching chamber, for dispersing or collecting liquids in soil, has a corrugated arch shape. The sidewall of the chamber is comprised of alternating slot-perforated peaks and valleys connected by slot-perforated deep webs. The unit surface length of perforated sidewall is greater than the unit length of chamber. A combination of interrelated dimensions and angles provide high leaching capacity, strength, and capability to nest for shipment. The sidewall is reinforced by vertically running ribs; the perforated web is reinforced by zig-zag struts. Ribs and struts are shaped and positioned to minimize blockage of the slot openings.