Volume between two irregular shapes given areas?

Question

I am trying to find the volume of a waste stockpile with the following characteristics. The top area is 35,189 units, the bottom is 698,886 units, and the angle of repose is 35 degrees. Help me out! Please provide any equations you used also.

Answer 1

Well, I'd assume the shape of the bottom and top are squares
Then the height would be about 227 feet
What you have then is the frustrum of a square pyramid.
V = 1/3*698,886* 295 - 1/3 *35189*68