Pond Boss Forums POND CONSTRUCTION Soil questions How much clay is needed?

You might want to use a coarse mixture of clay so the fines will leach into the rock and seal if you pack it thick being on the uphill side it might loose bond on incoming water pressure in the spring also build solid from the base up so it does not slide back into pond. When under constuction if there was water entering pond from shale bond might be hard to acheive.
Shale is sedimentry most shale in our area runs in fine layers we have had good sucess with a layer of 30 mesh bentonite applied before parging clay with an excavator.
If there is water pressure coming from the shale it will break the bond

Good Luck
Scott