Everett R Davis, 92Yarmouth, MA

5263792, Nov 23, 1993

Oct 26, 1992

7/966809

Everett R. Davis - Harwichport MA
Keith R. Bartlett - Groveland MA

W. R. Grace & Co.-Conn. - New York NY

E02B 1100
E02D 1900
E02D 3100

405 45

This invention provides an improved rollable subterranean drainage core device which has T-shaped finned projections to which may be adhered a water-penetrable soil filtration fabric. The fin structure provides impact resistance and high compressive strength while providing high water channel flow-through capabilities. An exemplary method for fabricating the drainage device involves extruding a unitary finned polymeric core sheet having T-shaped projection members on at least one major side thereof, and then removing a portion of the fins in a cross direction at periodic intervals along the machine direction, so that individual T-shaped projection members are spaced in rows and columns on the rollable core sheet. The drainage core member is particularly suitable for use in conjunction with waterproofing membranes.