Preformed Ponds

[vincente]

Tony, this is follow up to something I started 2 years ago. I'm on the archive 18th July 2002! I have laid perforated pipe in pea shingle all the way down the garden to the stormwater drain. I still can't resist the idea of a pond. Would a preformed rigid pond stop the percolation of a constant groundwater problem, forcing any water into the land drain?
Or would digging out to 20" start a major destabilisation of the situation? At the moment the flow tends to prefer to collect in the lowest point, rather than the land drain. When I previously had a flexible liner, the water collected under it until it flooded the lawn. Can I do this, or is it best to give in and fill the hole with topsoil and have a bog garden?

[84-1093879891]

Would it be possible to lay an additional length of land-drain from the proposed pond surround out to the existing land drain system? This would eliminate any problem of hydrostatic pressure developing underneath the planned rigid pond liner.

Ideally, you would surround the planned pond with a land drain at a depth at, or as near as you can get it to, the base of the pond liner. This can be surrounded with granular material to support the rigid pond liner and then, once all is backfilled and the pond is filled, any excess water accumulating in the pond pit would have an escape to the main land-drain system.

[vincente]

Tony, as usual you are inspirational. That seems like a great idea. The only tiny problem might be that the base of the pond is lower than the level of the land drain I have installed. But I suppose even then, the excess water would find its way into the system before any flooding.
Great site, great response times. Brilliant Tony.