I do not have any of the limestone layers in my immediate area (any rock we might hit would be sandstone) but just ten miles north of me on some ground we farm limestone layers are common. Funny how areas change over relatively short distances.
An excavator and dozer are the ticket for cleaning out muck. I have cleaned out three ponds with my dozer and it is no fun. Hard to keep the tracks on something not slick and maintain traction. With an excavator (especially if it has a long stick) can scoop out the muck while staying out of it and the dozer can keep it cleared away from the excavator so it does not have to move much or rehandle the muck to get it out of its own way.
I would love to have an excavator and may some day.
Cleaning out a 50 year old pond 
