Developments in My Garden - The Pond
In January 2009 work began on a pond in the lower garden. The subsoil is boulderclay with a sandy consistency so it would not hold water for a long period without a liner.
View of the area where the pond was to be dug out in July 2008.
The top-soil was removed and stacked outside the area to be re-profiled. There is a slight incline so the area was levelled out by moving some of the subsoil to the lower side first, then the excess was taken away to form the pond. The larger boulders were kept to be used for retaining the upper side.
There are some field drains passing through the area that take away the water which filters down from the higher ground. This could gather under the liner during very wet weather and would cause it to bubble up to look like a whale. So the drains were continued at the bottom of the dug out area.
The sides were given a gentle slope and a shallow shelf was left near to the edges to accommodate marginal planting. The level was checked by driving a small peg into the soil at the perimeter and using a long plank and a spirit level, another peg was inserted further around. This process was continued until there were pegs all around (two of them can be seen in the picture below).
The soil in the dug out area was raked over and all of the stones removed as they could damage the liner. For further protection, old silage bale covers were spread over the area. The gravel patch in the centre is to allow water below the liner to reach the underlying drain.
A 1mm butyl rubber liner was used as it is the most suitable for a pond of this size.
The water to fill the pond was taken from a deep well using a submersible pump. It was crystal clear for a few days, but turned a reddish colour due to the particular algae that must have been in the well water. So it should be possible to keep a flock of flamingos in pink plumage!
The excess liner was trimmed off and about 40cm all round was buried under soil or under some of the boulders which were placed on the edge.
Earlier a selection of pond plants had been grown in some tanks of water so they were ready for placing on the shelves which are about 20cm below the surface. After a few weeks the reddish colour had gone, but due to the soil at the edges the water remained a bit muddy because of the rain washing it into the pond. When the edging plants fill out this should stop.
At the end of the pond (in the foreground of the picture above) there is a bog garden which has a perforated liner to retain the moisture and a slight depression in the edge of the pond allows any excess water from the torrential rainfall this summer, to overflow into the area.
This view shows the sloping profile of the surrounding ground.
