For the part of the pond that is above ground, it would be a good idea to
use a styrofoam or similar insulation board to help the pond retain as much
heat as possible. Do not insulate under the bottom, as heat will come up
through the soil to help keep the pond critters at about 4C, 40F. The
exposed sides will carry heat away quicker than a submerged pond, but
insulated, it should be doable.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html

"Gill Passman" gillspamattaylorpassmanspam.co.uk wrote in message
.. .
Hi All,

After lurking on this group for a few months and a lot of research
elsewhere
I am almost ready to finalize the plans for our pond.

We will most likely be using pond liner due to the area to be covered and
the fact that it won't be completely square or rectangular. The structure
will be decking panels. I will probably need to put a grid in short-term
because of my 4 year old daughter. We are planning to keep fish in here -
hubbie wants Koi but this is still up for debate.

The pond is going to be raised around 2-3 foot above ground level. I was
wondering if we need to dig below the surface at all as well? The problem
is
that our soakaway runs around six inches below where the end of the pond
is
going to be. Of course there is the possibility to dig deeper at the other
end of where the pond is planned for.

Any thoughts on this would be helpful - especially on the need to dig and
if
yes how deep?

Thanks
Gill