I am building a pond and having an engineer do the plans on it, however, he is a ways out on getting to me to get everything calculated and I have an opportunity for some really cheap pure clay that is being removed from a place nearby. I would love to get a general idea on how thick the clay core needs to be for this pond so I can get roughly the correct amount of clay hauled in. The pond is going to be roughly 2 acres in size and 8 feet deep, the pond dam will roughly be 100 feet long and 12 feet tall. I was thinking the core needed to be 3-4' feet but I would love any opinions/guidance on this because I have limited experience with this. Thanks in advance