Some in the sandy soils use a concrete collar, 6 or 8 inches thick and maybe
a foot wide around the top edge of the pond to keep from having the soil so
easily displaced. But based on the fact that you have caving, I think the
easiest and best way would be to pull the liner back and build a concrete
block wall. It can be dry stacked, since it will not have to provide a
large amount of pressure, having water on one side and soil on the other.
You can start the dry stacking at one end of the cave in area and work
around the pond, and take the soil removed to start the next area of wall,
and throw it behind the wall to support the wall. For additional strength,
if desired, mix some concrete or mortar and put it down through the hollow
openings in the block and while the concrete or mortar is still in a fluid
state, push a rebar through. This will lock all of the blocks together.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"A.N.Other" wrote in message
...
"Drew Cutter" wrote in message
...
Are you edge's straight or angle ? supposedly angle edges are suppose to
prevent caving in.

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It had to be vertical, when I dug the original pond I chose a bad spot,
because buried behind the pond and below the trees is rock. go to
http://www3.sympatico.ca/b1wmah56 its the back wall of the pond. what
jappened in my case was that as the soil slumped at the top, it slid down
the rock and pushed the liner into the pond at the bottom.
ANO