Polystyrene beads for drainage fields

A preassembled drainage line unit comprising a perforated sleeve member and a loose aggregation of lightweight plastic beads enclosed within said sleeve member, each of said beads comprising a solid central portion of generally rectangular cross section, a plurality of solid legs extending a substantial distance from the top of said central portion and a plurality of solid legs extending a substantial distance from the bottom of said central portion, a plurality of channels each defined by adjacent legs and each having a substantial depth, the width of said legs being greater than the width of said channels so as to prevent the legs of one bead from nesting within the channels of an adjacent bead.

A lightweight expanded plastic bead for use as aggregate in a preassembled drainage line unit, said bead comprising a solid central portion of generally rectangular cross section, a plurality of solid legs extending upwardly a substantial distance from the top of said central portion and a plurality of solid legs extending downwardly a substantial distance from the bottom of said central portion, the legs extending from the top of said central portion being substantially aligned with the legs extending from the bottom thereof, a plurality of channels each defined by adjacent legs and each having a substantial depth, the width of said legs being greater than the width of said channels so as to prevent the legs of one bead from nesting within the channels of an adjacent bead when in use, the length of the sides of said bead being no greater than three inches.

A preassembled drainage line unit comprising a perforated sleeve member and a plurality of lightweight plastic beads enclosed within said sleeve member, each of said beads being of substantially the same configuration and comprising a solid central portion of generally rectangular cross section, a plurality of solid legs extending a substantial distance from the top of said central portion and a plurality of solid legs extending a substantial distance from the bottom of said central portion, the legs extending from the top of said central portion being substantially aligned with the legs extending from the bottom thereof, a plurality of channels each defined by adjacent legs and each having a substantial depth, the width of said legs being greater than the width of said channels so as to prevent the legs of one bead from nesting within the channels of an adjacent bead.