Polystyrene beads for drainage fields

DETAILED DESCRIPTION Accordingly, the primary object of the invention is to provide an expanded plastic bead of novel configuration which is strong and durable, which provides greater void space to promote the flow of waste water through the drainage units, and which provides maximum surface area for bacteria to attach to, the bacteria acting on the sewage effluent, returns it to the soil.
The objectives of the invention are accomplished by providing a configured block-like polystyrene bead made primarily from recycled polystyrene materials of low melt flow to give the bead toughness and durability.
The bead is formed by extruding material through an appropriately shaped and sized extrusion die, cutting the material to form beads of a predetermined length, and heating and expanding the beads so that each of its six sides is at least one inch in size.
The bead has a longitudinally extending central portion and a plurality of spaced legs, preferably at least three, extending upwardly and three spaced legs extending downwardly from the central portion.
A rib projects outwardly from the central portion on each side face of the bead.
Channels are formed between adjacent legs and the width of the channels is less than the width of the legs.
When contained within a drainage unit, this prevents the legs of one bead from interlocking in the channels of an adjacent bead and maintains maximum void space.
Similarly, the ribs on the side faces of the beads maintain spacing between adjacent beads to maximize void space.
The large void space allows for maximum flow and storage of waste water.
In addition, the novel bead configuration with the legs and channels provides maximum surface area for growth of bacteria which enhances the breakdown of sewage waste.
Other objectives and advantages will become apparent from reading the following description of the invention wherein reference is made to the accompanying drawings.