Patent ID: 8061020

Claim:
An apparatus for making a drainage element comprising a tube for passing light weight aggregate therethrough; supply means for supplying a web about said tube, said web having a first longitudinal net strip secured to a second longitudinal filter strip along respective longitudinal edges thereof; said filter strip characterized in being permeable to the passage of water therethrough and impermeable to the passage of fine particles of solid material from the water passing through said filter material and said mesh material has a regular pattern of openings of a size of from 1/16 inch to 1 inch; forming means for shaping the supplied web about the tube to dispose longitudinal edges of said web in overlapping relation; securing means for securing the overlapped edges of said web together to form a sleeve about said tube; tying means spaced from said tube for intermittently applying a tie about said sleeve to close said sleeve on itself; and means for moving said sleeve from said tube.