| 摘要 |
A laminated sheet which is useful as part of an underground drainage system for a basement is disclosed, and which includes a layer of polystyrene and at least one layer of a polyolefin laminated to one side of the polystyrene layer. The laminated sheet is molded so as to include an array of spaced apart projections extending laterally outwardly from one side of the laminated sheet thereby forming a series of drainage channels.
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