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• smaller or larger pieces are acceptable. Our discussions with the previous <br />contractor who constructed most of the drain indicates the rock was covered with <br />filter fabric. We recommend this practice be continued. The drains can be ended <br />wthin the top 50 feet of the RDA. <br />The initial drain rock was obtained from quarry operations outside the RDA <br />area and consisted of native sandstone. As the RDA increased in elevation the <br />sandstone was obtained from seams within the RDA perimeter. The sandstone used <br />should be durable and not be contaminated with significant quantities of shale or <br />overburden soils. <br />Roads on the Fill Surface <br />We were requested to comment on the suitability of stabilizing the surface of <br />• the fill using excavated sandstone from the RDA perimeter. This has occurred at <br />various stages of RDA construction. The stabilization has typically been performed <br />when inclement weather or processing problems have resulted in high moisture <br />conditions which inhibit equipment traffic on the pile. Stabilized areas (roads} were <br />typically provided along the face of the RDA, around the back and intermittently <br />across the RDA or radially from the refuse discharge area. Based upon our <br />discussions with previous contractors the material used consisted of soil and rock <br />dragged from the native slopes of the pit area. Mr. Augustine stated that they tried <br />to avoid building "roads" adjacent and parallel to the RDA face, instead trying to <br />orientate them perpendicular to the face. <br />Provided the material used is primarily sandstone and the stabilized areas are <br />• intermittent vertically and horizontally, then we do not believe they will significantly <br />25 <br />