Patent ID: 9556576
Date: 2017-01-31
CPC Classifications: E02B,E03F

Claim:
1. A chamber, comprising: 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, wherein the end crest sub-corrugation includes a substantially constant width.