I've literally just completed a similar project, albeit for a different reason. We drained and renovated our 1/2 acre pond to eliminate a trash fish population that migrated in during a flood as well as reconfigure aeration. Common carp had created a turbidity problem that was being exacerbated by our aeration system, we found the diffusers had created little volcanic looking spouts of silt around them over a couple years since the flood. Turbidity collapsed the food chain and forage base = worthless mudhole..

With a cheapo 2" pump, running it while we were around the house (evenings and weekend) it took a couple good solid weeks to drain.. Would have gone faster had I adapted a larger tank to the pump, but just never did it. Surprisingly the pump actually sucked out a darn good bit of the silt during the drain process. The rest took several weeks to dry enough to get a tractor in there, the drought here in the south helped some I'm sure. It was still pretty sloppy, but as long as we dug out to the clay pack and didnt try to run off through the slop (about 18-20" deep) we didnt have a problem doing it with the FEL.

Blocked the diffusers up about 18-20" off the bottom and started refilling.. About 2ft from full pool now and new fish will de livered next week. Not a horrible process, just gotta be deliberate and patient.