After the installation of main and lateral drains, the slit drains are installed.
These drains are 50mm x 300mm and are cut at 90 degrees to the lateral drain (photo A). The intersections are then hand cleaned to ensure that a clean interface between the lateral and slit is achieved (photo B).
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A.
sandslit - 90 degree cut
B.
sandslit - slit achieved
The slits are backfilled with gravel, then a blinding sand (photo C), taken after slit completion and first sand application and brooming).
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C.
sandslit - after completion