Garden Drainage - General Installation Guide

Single Pit Layout.

1. Choose the wettest area of the garden as the site for the main pit and excavate a square pit approx. 1 meter squ. x 1.4 metres deep, ensuring that if you are digging through a lawn the top slice including the turf should be about 6” thick. Place this to one side. The remaining surplus to be deposited in the skip.
2. Locate the nearest or most convenient surface water drainage and excavate pit to receive the impact mole.
3. Mole between pits aiming for a fall towards the main pit. The moled hole in the main pit should be approx.18” below ground level.
4. Draw in the 38mm duct.
5. Place 20mm stone in pit about 100mm thick
6. Position chamber in pit on the stone and check for level - lid should be about 25mm below lawn level so that a lawn mower can pass over the top of the lid.
7. Cut a hole in the chamber to allow the duct to reach into the chamber by about 2”.
8. Line the sides of the squ. pit with Plantex fabric allowing a 2ft overlap over the edges of the pit and fill around chamber with 20mm stone to within 6” of lawn level (to suit top slice).
9. Tape 20mm pipe and cable together and feed through the duct. Pull about a meter of cable into the chamber. Sit pump on flat stone in pit base (piece of paving slab?).Fit Plasson elbow onto the 20mm pipe and connect to fitting on the pump ensuring that the float on the pump cannot touch the sides of the chamber (the cable to the float can be shortened to achieve this)
10. At the outlet end cut off duct in exit pit allowing 20mm pipe to be adapted to 15mm copper pipe which is then formed so that it drains into the grid. Cut off cable ensuring that there is ample length to feed into the house or garage and onto its designated socket. Cable is fed into overflow type pipe underground and fed neatly to a point where it is necessary to drill through the masonry to a position near the electrical socket.