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'from existing topography around the wa:>te rock pile and tieing projected contour lines to the <br />projected Deadman Gulch alignment. _ <br />The intersection of the historic surface plane (extending from _the highwall) with thepad area <br />-- - - - <br />was estimated visually by "eyeballing" f1rom a point on the pad and looking up hill above the <br />high wall (to the east) and visually projecting a line from the hillside surface plane above the <br />high wall down to pad. This was done in at numerous locations along a line from near the fuel <br />tanks to the near Deadman Gulch.. Points were painted on the surface and then surveyed as part <br />of the topographic survey.. <br />,the _volume of material to be excavated :From the waste`rock pile (in-order to-expose-the-historic <br />Deadman Gulch surface) was calculated using digital elevation surface models of the existing <br />waste rock pile and the estimated historic surface. It was assumed that all material will need to <br />be removed south from a line 15 feet north of the estimated De adman Gulch. This line was <br />assumed to be the toe of the proposed excavation. The cut slope was assumed to be <br />approximately 2:1. A DEM of the proposed excavation surface was created and cut differentials <br />between the existing and proposed surfaces were created. The attached figure shows the <br />estimated cut depths over the proposed excavation area. (Please note that there are a few <br />artifacts from the modeling that show slight fills at the downstream end of the modeled area. <br />There are minor and were not addressed[ at this time.) The total cut volume was calculated to be <br />9,000 cubic yards. However, piezometer drill holes indicated that fill depth (and the historic <br />--r - - <br />peadman Gulch channel) near the upper end of the waste rock pile may be five to ten feet deeper <br />than estimated and the total volume may be closer to 10,000 cubic yards., <br />Deadman Gulch Realignment <br />Upon completion of the waste rock removal effort, Deadman gulch flows will be released to their <br />native channel pathway (tentatively identified within Figure B.2). This will be accomplished in a <br />step-wise fashion in order to ensure that the flows are returned to a pathway devoid of any <br />residual waste rock material. Flows will. be maintained within the amended channelization <br />features until all waste rock is removed. The native channel area will be re-contoured to reflect <br />the native topography. Flows, when released from their containment features will then occupy <br />this pathway and continue down the natural course of the Deadman Gulch/Fault system. Prior to <br />the release of flows from the amended containment system, the native flow pathway will be <br />tested to confirm the absence of any waste rock residue. Samples of soil/alluvium will be taken <br />along the length of the re-established flow pathway and analyzed for acid base accounting <br />parameters, as well as metals content. The results will be compared to other native channel <br />characteristics to define the range of acceptable conditions that measure/confirm the absence of <br />12