US Patent 9809968 Leaching chamber having sidewall with tenced louvers

A corrugated thermoplastic leaching chamber has sidewall louvers that define sidewall slot openings. Each louver comprises an outward extending canopy, a cap integral with the outer end of the canopy, having a down slope greater than the slope of the canopy, and a preferably concave fence at the inner end of the canopy, for inhibiting ingress of soil. The chamber may be made by first thermoforming sheet material, preferably two-layer PET plastic sheet to the shape of the chamber, followed by mechanically cutting and deforming the sidewall, to create the opening and the fence.