I'm not sure about draining the pond, never done one before. Since it was a sand quarry, it is filled from either from ground water or a spring below the water line. All the aerial photos I found seem to show a constant water level. It has higher ground around it and there is no drain/overflow pipe, no lower ground without going over the hill first. I would have to pump it out with a trash pump to a creek 500 feet +/- away from the deep spot. And I don't know how quickly it would try to refill. Is it feasible to just lower it? Would a 3" trash pump do the job and how long would it take? How long before a lime truck can get in it?
