I prolly wont be much help for ya but I will take a stab at it. If I was going bring in equipment to dig it out I wouldn't worry bout the vegetation because it will be removed also. If theres no fish in there tht you care then drain it. When I drained mine (only halfway). I took a bucket and put the pump inside it. Made the bucket like a big washing machine tub. It had lots of small holes in it. Mine I was more concerned with mud clogging it up. If you get some kind of trachoe to clean it be careful. It could disrupt a clay line which hopefully it has. Hopefully I didnt create more questions than answers which I tend to do.

The people who say I can't do it can just sit the @^#% down and watch me. Friends call me Rusto I also subscribe to pond boss mag. http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=504716#Post504716