Most alluvial gravel is easy to scrub, the real secret is to use the weight of the gravel to scrub the gravel. As you can see here at around 75 yards per hr, with a 5 ft diameter screen 25 ft long you will get a good scrub. The 1 inch water spray bars pushes a lot of water through the media creating a very good liberating scrubbing action. Using an excavator to feed with is usually the most long term productive way of introducing material to the washing system. The first 6 or 8 ft of blank barrel helps wet, distribute irregular sand and gravels to your screens and recovery system be it simple sluices, jigs, or any other type of gravity recovery system.
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