All you need is gas powered fire pump, a 55 gal drum (sealed) a 15 length of hose, and a 50 to a hundred foot length of hose. Cut to holes on the drum, one about 3/4 ways, to the top and one about a quarter ways to the bottom. Attach a ball valve for each hose. Run the top valve from the barrel to the water in on the fire pump. Attach the longer hose to the ball valve. With the ball valves close, fill the barrel full of water, the top valve and let that hose fill with water to prime the pump. Shut the valve back once it's full. Once done, have the longer hose in the water, crank the motor, open the valves and wa-la, instant coin retrieval. The coins come into the bottom of the barrel and only dirty water goes through the pump.
I'm in if you need help