Thanks for the suggestions. Our farm is about 2 miles east of I-35. I talked to a dozer operator a little while ago who had built a few tanks in the area, but I didn't get the feeling that he was very knowledgeable about different construction techniques or soil types. I think the extent of his tank design was to do what he did on the last one...

I would appreciate you checking around. Per Bob Lusk's suggestion, I also contacted Johnson Lake Management in San Marcos, so they might be able to help me with some design work and soil analysis.