Boy, this got long.
JAS, I've never talked with anyone who has both educational credentials and practical experience in this matter. If you ever make it to the D/FW metroplex, I would love to sit down and talk about clay with you. You will do most of the talking and I can draw a pretty good crowd of listeners from this area. BTW, I have no idea what soil types or weather conditions exist where NashFireman is going to excavate and build. Nor do I know his tolerance for small leaks.
However, for practical reasons, I have to disagree with you on the need to core. In your part of the world, a pond that you allude to as not leaking very much can be a disaster in my drought stricken part of the world. I've not seen a leak slow down when it runs between natural ground and piled and mashed clay. I think of it by saying that I buy health insurance before I get sick and life insurance before I die. The uncored, slightly leaking pond is the pre-existing condition that the insurance guys don't like hearing about.
In a perennially dry area which we usually have, the % of clay that goes into making up sandy loam is critical. If too little clay, the sand all runs off the face of the dam into the pond. If too much clay we get cracks in the face when water recedes. And, it darn sure recedes in 100 + temps. The cracks close when we get a good rain but somehow I feel that the integrity has been compromised.
In certain areas around D/FW we have black gumbo clay soil. When it dries, it shrinks and when it gets wet, it expands. When it shrinks, we get huge cracks in the ground. This happens every summer. Thus, we get a lot of busted concrete slab foundations and cracks in walls. Even after repairs, you almost can't sell the house. I've never tried to build a dam in that type of area or talked to anyone who has. But, I've always wondered what would happen, with or without coring. What are your thoughts? If you make it to D/FW, I'll buy the beer and and listen.
