I want to build a dam to raise the water level of an existing pond. Currently the pond is 30' x 50' and the dam will be on the long side, and would raise the water level another foot or so. However I don't have enough clay on hand to build the dam, so I was wondering If I could make a mix of the clay I have, bentonite, and the dirt I dug out of the pond. My plan would be to dig down below current water level, and build the dam up in lifts compacting as I went up. Would that work? If not does anybody have a better idea?