For an infrequent use, I would get the 2" semi trash pump from Harbor Freight, some suction hose, a good strainer, and some poly pipe. Poly pipe is a lot cheaper than discharge hose, and you can hook it up directly to the pump outlet with the proper fittings. That's the way I do it. Pump the pond down, get a long reach track hoe scheduled to come in right afterward, and muck it out. Let the springs refill it.