Kurt,
I admire your can-do attitude, but that muck is about as heavy as wet concrete. I dug out a 10 x 12 ft area by hand about 4 ft down for a boat slip. I filled 5 gal buckets 1/2 full and carried them about 20 ft up the bank. I was about 35 yrs old and in very good shape when I did this. After about 5 hrs my biceps were cramping up so bad that I had to keep my arms straight. I could hardly get out of bed the next am because of my sore hamstrings.
"Conan the Barbarian" was just on TV and when you mentioned digging your areas out by hand, I thought of the scene where Conan get bound to the grinding mill and spends his youth pushing that around, eventually just by himself. I you dig you holes out by hand you might end up with a body like Arnold, albeit hormone free....
Seriously I would suggest getting a part time job and saving some money to get a long reach excavator or drag line in there. With the size you mention, I'd think they could be done in a day. At $100 or even $150/hr, that would be a much better approach. That would depend on having a place where they could place the material until it dries. You may need to move it twice, but that would sure be much easier.
Bill