I have a test hole that is 2 1/2 good clay & then I began to get into some gravel.The clay that is mixed w/ this gravel is good....stains my hand brown when I sqeez it...stays together when balled up.I had one contractor say it would be ok nto use on the back side of the dam & another contractor says he is not interested in diggin the dam.I have enough clay to dig the dam.When i was diggin in the clay/gravel mix the excavator struggled to dig b/c it was hardto dig.Anyone have any suggestions.If gravel is such a bad thing why are all these gravel pits that i have been fishin keep me commin back??????