Abstract: A plastic arch-shape cross section corrugated stormwater chamber has a multiplicity of crest corrugations and valley corrugations which run transverse to its length. Sub-corrugations run along part or all of the arch-curve lengths of either crest corrugations or valley corrugations, or along both of them. A sub-corrugations are smaller in dimension than an associated crest corrugation or valley corrugation. Sub-corrugations may taper in width and depth and may taper to nothingness. A compound convex shape end cap, useful for closing off the ends of stormwater chambers, has substantially vertical corrugations with analogous sub-corrugations.

Abstract: A chamber is disclosed. The chamber may include a base, a plurality of alternating crest corrugations and valley corrugations running transverse to a length of the chamber, wherein the crest corrugations decrease in width with elevation from the base, and the valley corrugations increase in width with elevation from the base, at least one crest sub-corrugation running along at least a portion of a crest corrugation, at least one valley sub-corrugation running along at least a portion of a valley corrugation an end crest corrugation positioned at a terminal end of the chamber, and an end crest sub-corrugation running along at least a portion of the end crest corrugation.