Vertical soil drainage component acting through different strata - has central portion formed by transverse partitions and walls bearing against permeable layers

摘要

The component gives vertical drainage through different soil strata, and comprises a central strip portion with lengthwise slots on opposite sides covered by a water-permeable layer. The central portion is formed by partitions (22) at right angles to the layers (21), and joined to each other by walls (23) bearing against the layers. The walls between the partitions can run against opposite layers alternately, and they and the partitions can be of 0.5 mm. thick plastic, the partition pitch being 2.5 mm.