Pond Boss Forums POND CONSTRUCTION Soil questions New pond sealing

Another option would be dig a trench around the pond down to the modeling clay layer. Drop a liner, roofing membrane, plastic sheet, etc. vertically in the trench all around the pond, sealing any seams from the clay layer to the top of the soil. Backfill with dirt. That's what one county NRCS does here when they have a leaky pond. Pond might not seal 100%, but it will leak a LOT less than what it does now.

They said they do that when clay and machinery isn't available. They can do that in a narrow trench as long as the sides don't collapse.