I will have to excavate my pond from flat ground, no dam, no runoff to speak of. And will line with vinyl or bentonite (mixed blanket with a foot of natural soil to cover.

I have read in numerous places that the slope of a pond should not exceed 3:1 to keep soil from sliding down the liner. I assumed this meant 3 inches per foot, is that correct? Or is it 1 foot drop in 3 foot of run? Doesn't sound like much, but a difference of 7.5 ft of depth or 10 ft in a 60 foot diameter pond is quite a bit.

Do I really need to pay that much attention:
1. with a vinyl liner?
2. with bentonite liner?

Will the topsoil slide down off of these, will the bentonite layer slide down leaving no seal at top?

etc. etc.

Greg

3:1 means 1 foot of drop per 3 feet of run.

You probably don't want to exceed that slope with either method of creating your seal.

That is good news, it means I can get to 10ft deep. I thought I would set the liner on a round shape with 3:1 slope. then build any points or irregularities with dug out soil.

Gmoore, If it were my pond, and it's not, I would opt for the bentonite as the seal. Any Liner will eventually have to be replaced and if the bentonite is disced and compacted properly, it will last a lot longer.

The 3:1 slope would not be an issue with bentonite, but a steeper drop could make getting out of the pond very difficult.

Thanks for the info, I have two test holes that I shoveled yesterday to test bentonite, it looks very promising so far.