Prefabricated ponds....
Prefabricated ponds, commonly known as mounded ponds have the advantage of being easy to install
and require little very planing. The main disadvantage would be the cost, especially with the more durable thicker
types. These can be obtained from either an aquatic or garden centre.
Before buying a moulded pond there few considerations to address:
Wildlife ponds will need a sloping side to allow creatures to enter and exit the water.
If using marginal plants, make sure the preshaped liner has large enough shelves to accommodate
them.
If you intend keeping fish such as koi, the pond needs to be atleast 45cms deep.
Moulded ponds normally have a lip on the outer edges, this is quite difficult to hide using vegetation, so
you might have to consider using materials such as paving stones.
Installation of the prefabricated pond....
Lay the liner the right way up, on the intended site. Make a mark in the soil with a spade adjacent to the outside
diameter of the pond. After removing the liner, dig a hole to a depth of the first shelf , after this rake the soil and remove
any sharp objects.
Replace the pond on to the soil, apply gentle pressure the the base of the pond, then remove the pond once more.
The base of the pond should have left an indentation in the soil, dig out the soil to a depth of 5cms more than
the bottom section of the pond. Compact the soil, remove any sharp stones, then place the preformed liner back into the hole,
checking it fits ok.
Fill the base of the hole with about 5 cms of building sand, compress the sand and replace the liner. Check
that the pond is level with a spirit level, if necessary adjust the excavation.
When the pond is level, fill the with water to about 20cms, this will give the pond stability by moulding itself
into the excavation. Now back fill the excavation to the level of the water, making sure the soil used is stone free.
After each fill firm the soil, either with your boots or I use a sizeable rounded piece of wood.
Add another 20 cms of water and repeat back filling process. After each fill check that the pond is level with a spirit level.
If using edging stones add sand under the rim of the pond liner, compact this layer before laying the edging stones on a bed of cement.
