Just finished with this project on 3/4 acre and heavy equipment contractor. 19 days, layers of limestone bottom, 56 truckloads of clay, 45000# bentonite. They did a beautiful job, but pricey, messy, and having a place for alot of sludge helped.
Where in Indiana are you?

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=475818#Post475818

sean