Patent ID: 7052209

Claim:
An apparatus combination which comprises: an arch shape cross section thermoplastic chamber, for receiving or dispersing water when buried within water-permeable media, comprising a plurality of substantially identical alternating peak and valley corrugations, an open bottom, and an arch shape cross section geometry; wherein, at least one peak corrugation at a first end of the chamber is smaller than said plurality of corrugations, so that the opposing end of a like chamber may overlap the smaller corrugation, to thereby connect and form a joint between the chambers; and, a domed endplate, for fitting within the interior of said first end smaller peak corrugation, for closing off the first end of the chamber, to inhibit passage of media in which the chamber is buried; wherein, the size and shape relationships among the endplate, the first end smaller peak corrugation, and the peak corrugation plurality is such that the end plate may alternatively be positioned within the interior of a peak of said plurality of corrugations, to inhibit passage of media or water.