Hello,

I recently had a pond dug in heavy, undisturbed clay below the water table. The wall slope was fairly steep, I relied on the contractors experience and he compacted the banks well with the excavator bucket but I'm quite sure that the slope will not be reliable in the long term (I can dive off one of the banks that drops about 12 feet.)

Can anyone comment on what the maximum slope will be after settlement and freeze-thaw?

Boomer,

It sounds like all the wall slope will be under water. Is that correct? If it is, and the clay is stable, I would think it could stay in that shape for a very long time. My guess your biggest issue might be if the water level drops a bit and you get some wave action, that could start eating into the bank.

We're in the process of removing clay to build a road, and the borrow area will eventually be under water. At the waters edge we are going to leave a 20 ft wide band that will slope from 1 ft below water level to 1 ft above water level. Then we will cover this with rock to prevent erosion. Then at the 1 ft depth we are going to drop almost straigh down to about 15 ft, to prevent weed growth.

We've got a 10 year old, 25 acre pond and in the borrow area have a similar straight drop off, and my son has scuba dived along it and said the bank still goes straight down.

Bill