Unfortunately the best I could do on the slope was 4:1 down ~7ft to the clay layer.
I tried a steeper slope but got my dozer stuck on the bank, the tracks just spin in the loose soil at a 3:1 slope, luckily I had my excavator to help pull it up.
Will a 4:1 slope all the way around the pond create vegetation problems for me? I don't want cattails, etc...
Latest pictures:
Rear Banks 
