what kind of bentonite are you using? if powder, i'm not surprised it didnt work. if chip, then you have a more serious problem and I concur with dave.

there are different brands of chip (normally i see/use 3/4" to minus chip from 40 lb bags......wyoben, enviroplug....there are probably many other brands). try chip first if you havent already, if that doesnt work, you may need to consider draining and installing thick lining of good clay soil

GSF are people too!