Behind the base of the wall a land drain is put, on a bed of clean stone about 6 - 10" thick. Keep the land drain level, it will eventually be terminated in a surface water drain or soakpit.

The land drain is then covered with more clean stone. The land drain negates the requirement to inset weep holes in the bottom of the wall, which will produce unsightly staining of the face of the wall below them. The cavity is filled with concrete, using a vibrating poker to ensure the concrete is compacted - this is very important to maximise the strength of the structure.

A sheet of geotextile material is put over the clean stone - this will prevent fine material from eventially choking up the land drain. The rest of the trench is then backfilled with more clean stone (not shown here).

Before backfilling with clean stone, the back of the wall is covered with DPM and a layer of expanded polystyrene to protect the DPM from the stone. The DPM gets surface water down to the land drain and prevents the water from soaking into the wall. An alternative is to waterproof the wall with bitumin paint.