US Patent 7811028 Hooded check tube

A check tube is sealed on one end and may be open on the opposite end. The check tube may have a cape, a flap and/or a hood attached to the check tube to, among other things, anchor the check tube and/or to prevent water flow, and thus erosion, between adjacent check tubes, beneath the check tube and/or downstream of the check tube. A temporary pocket defining a subset of the volume of the check tube is provided in the check tube and filled with fill material that expands after being introduced to water. Just prior to, during or after installation of the check tube, the pocket is opened, broken or dissolved and the check tube is introduced to water thereby allowing the fill material to expand to the full volume of the check tube.