A muddy mass of debris left in a logging yard moves through the chutes and conveyors of the Walker DeRocker and comes out in four separate piles: small rocks, large rocks, fine soil and bark. J&S Walker Manufacturing and Mike Morris of Days Creek were granted a patent Nov. 7 for this log yard waste separation system, which has been running at C&D Lumber in Riddle for the last four years. In unpaved logging yards like the one at C&D, layers of rocks sit under the piles of cut logs to keep them clean before they are picked up to be processed at the sawmill. The Walker DeRocker is meant to transform the yard debris left behind into products that can be reused or sold.