Our land is basically clay with a small bit of soil on top. The water table is only 10 feet underground. There is a massive sawdust pile that is at least 30 years old that is partially decomposed. The highest point is about 20 - 30 feet off the ground. I've just finished reading Mike Oehler's book and I am leaning towards the shed roof flat land design. Could anyone make a suggestion as to whether building into this saw dust pile would work and if it would be advisable? Thank you so much for your time.