I have a 48 year old pond that I have owned for 18 years I have tried to dig up and recore the dam I have been dredging muck out with a trash pump for years. Now thanks to the California drought it has dried up for the first time. It's about 330' by 110' and 20' deep six feet of muck so I should have at least 26' of depth when done. I have discovered that so far I think that they didn't do a layer of clay on the pond bowl.