Removal of water in heavy clay subsoil can be achieved by pipe alone but to be fully effective the drain spacing has to be very close and will become very expensive and therefore usually uneconomicThe alternative is mole drainage. Mole channels are installed by pulling a riper fitted with a bullet and an expander through the heavy clay and across tile drains with permeable backfill. Mole channels behave like pipe drains but are much cheaper and an added advantage is the fissuring, usually
produced above the channel which aids rapid water movement. Mole drains rely for outfall on a system of permanent pipe drains which have permeable backfill ( gravel, sand, crushed stone) over pipes. Mole channels are drawn over these drains so that thebullet of the mole plough penetrates the permeable backfill. Water passes down through the moling fissures to the mole channel and then via the permeable backfill into drains. Having ensure that good mole channels have been formed, the system should provide rapid water movement for a number of years.

Mole plough foot and expander