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road and natural hill slopes), In essence, the material would be rolled-back towards the north to fill in the <br />cut slope created by the pad and road. This approach relies on certain site aspect assumptions as follows; <br />The area to the north of the waste rock pile is largely comprised of alluvium and contains no <br />surface expression of rhyollite (the acid bearing formation associated with Gold Hill) (samples of <br />this material have been collected and analyzed - results were provided in Attachment A, Table <br />A.2). Thus, the placement of the Level 6 waste rock to the north, would put the material on top of <br />a geologic formation found to contain a natural buffering capacity. <br />It was assumed that there are no groundwater flow pathways that would contact the moved <br />material. This assumption was based upon historic observations which indicate that there are no <br />surface expression seeps along the north side of the exposed portal face, pad or access road. <br />• Based on surveyed information, the volume of material to be moved from the estimated native <br />Deadman Gulch channel would range from 9,000 - 11,000 cubic yards of material. Very <br />conservative assumptions were folded into this volume estimate (Black Creek Hydrology <br />Associates). <br />Figure B.2 depicts the proposed Level 6 pad waste rock removal effort. The proposed amendment permit <br />boundary (wide red line) is depicted within this Figure. The information contained within this Figure was <br />`estimated' using three-dimensional surveyed points (shown in Figure B3), gathered by Black Creek <br />Hydrology LLC in order to determine the volume of the waste rock to be removed, and its appropriate <br />placement based on the area it will occupy. Figure B.3 shows the estimated excavation depth to remove <br />the portion of the waste rock pile that occupies the Gulch native channel. These estimates were based on <br />the hypothesized channel alignment and estimated historic contours that were extrapolated from the <br />adjacent exposed ground surfaces. In addition, the information obtained from the newly installed <br />piezometer wells was incorporated as validation points. There were assumptions applied to this estimate <br />as follows: <br />0 <br />• Waste rock will be removed 15 feet from the Deadman Gulch flow pathway centerline (narrow <br />blue line `15' Channel offset). The Deadman Gulch flow pathways IS CURRENTLY <br />UNKNOWN, and was estimated using projected underlying topographic contours (wide blue line <br />`Historic Estimated Channel alignment'). <br />• The waste rock would be pulled back to achieve a 2:1 slope which matches adjacent hill-slope <br />aspects. In order to meet BLM's aesthetic goals of `blending' site features into the natural setting <br />contours, this slope/aspect ratio was applied. <br />• The removed waste rock would reach a crest (wide orange line) and blend with the historic <br />underlying contours (dark black lines). <br />The anticipated step-wise progression to accomplish the waste rock removal is as follows; <br />• Removal will likely begin at the southern corner closest to the Deadman Gulch headwaters area. <br />The waste rock will be removed in layers to allow for drying/draining of underlying material. <br />9