You should be working with cohesive soils when building a pond. Here is some reading that might offer some hints and tips:
http://www.iowadot.gov/erl/archives/Apr_2004/CM/content/6-40.htm


www.hoosierpondpros.com


http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).