Drainage
There are several ways of draining a lawn which gets waterlogged.
A soakaway 1 metre x 1 metre x 1 metre
A soakaway dug out at the lowest part of your lawn is reasonably simple to install. This will collect water from a waterlogged lawn on a clay soil base. Depending on the size and shape of your lawn, it can be advantageous to dig out more than one soakaway.
Remove turf and place to one side using a half-moon shaped edge cutter. Cut a grid about 300mm square over the area. Then, cut out turf about 50mm thick, one by one using a spade. By cutting even sized turf, they will be easier to re-lay. Dig out a hole 750mm x 750mm by 1 metre deep - you may need to go a little deeper to find reasonable draining soil. Stack the topsoil on a polythene sheet to avoid damaging the lawn.
Fill the hole, firstly with brick rubble or large stones about 600mm deep. Then place a 150mm layer of gravel, sand or small stones. Finally replace the top soil, which should be about 150mm deep. Lightly tread soil down and replace turf. Water the turf if it has dried out while stacked.
Soakaway trench
If the lawn is level and water lays on the surface, a soakaway trench could be the answer.
Dig a trench about 600mm deep and 600mm wide along the length of the lawn. Cut out the turf as described earlier, and put them to one side - stack the topsoil on a polythene sheet to avoid damaging the lawn.
Fill the trench firstly with a 225mm layer of brick rubble. Then place 200mm of pea shingle, gravel or sand. Replace the top soil, tread down and replace the turf, which may need watering if it has dried out.
Single pipe drainage
Plastic pipe 3 metre in length and 100mm in diameter can be bought for land drainage. It can be joined using straight coupling pieces and can be easily sawn to length.
The pipe is perforated to allow water to enter.
Cut out the turf as described earlier, and put them to one side - stack the topsoil on a polythene sheet to avoid damaging the lawn.
Lay the pipe in the trench 300-600mm deep, with the holes facing downwards. This will stop soil and small stones from getting into the pipe, but will allow water to enter. Feed the pipework to a soakaway at the lowest point, as described above, so that the water can drain away.
The soakaway can be a simple affair, a hole dug out 1 metre deep x600mm x 600mm. Put brick rubble and stones in the bottom to a depth of about 600mm. Then place a 150mm layer of pea shingle or coarse sand and finally a layer of top soil. Terminate the pipe in the centre of the soakaway.
Herringbone drainage
Herringbone drainage can work out to be quite expensive and is only necessary if your lawn is waterlogged over the whole area.
Using a line, mark out the main drain pipe from the highest part of the lawn, to the lowest.
Then mark the side drains which connect to the main pipe, forming a herringbone pattern.
The side drains join the main pipe at a 45 degree angle.
Remove the turf carefully and place to one side. Dig out the main and side trenches about 300mm wide and to a depth of 750mm to 1 metre depending on the soil type, to accommodate the drainage pipes.
Lay pipes on a bed of pea shingle and then cover pipes completely with pea shingle.
Earthenware pipes - You can use earthenware pipes laid end to end, leaving a small gap between each pipe to allow the water to enter the pipe. Place pieces of broken terracotta flower pots, or broken roof tiles, over the cracks in the top of the pipes. This avoids soil and small stones getting in, leaving sides and bottom of joins open to accept the water.
Plastic pipes - You can use 3 metre plastic pipes which have many holes pierced in it to allow the water to enter. This pipe is laid in the trench on a bed of pea shingle with the holes facing downwards.
Space side drains at 3 metre intervals for clay soil and 8 metre intervals for loamy soil.
Connect to the main pipe by means of a plastic coupling.
Check the fall of the trench with a long length of timber and a sprit level on top. The fall should be 300mm in 33 metres to allow water to drain through the pipes.
At the lowest end of the herringbone, dig out a soakaway about 1.2 metre deep and terminate the pipe in the centre of the soakaway.
Back fill the soakaway with brick rubble 1 metre deep, 150mm of coarse sand or pea shingle and 150mm of top soil.
Replace the turf.