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From the position of the feature on the slope relative to the former bench and erosion <br />control, we concluded that the origin of the observed feature was compaction of the <br />topsoil placed on the slope during reclamation. Immediately above the feature, the <br />erosion logs had silted and overtopped two years ago, providing a water source to <br />saturate the topsoil and allow compaction in the area noted. The lack of a continuous <br />crack or evidence of movement, combined with the feature having vegetation along its <br />length, refutes the inference that this is an instability feature. <br />Also in Section III, Comments-Compliance, under the heading, Slides and Damage you <br />state, "A zone of instability was observed at the western toe of the Rock Fill, adjacent to <br />the paved roadway (Photo 3). Although the surface was dry at the time of the inspection, <br />it appears that excess water may be moving out of the slope on a seasonal basis. The <br />surface of the soil is disturbed, and the predominant vegetation at the location is field <br />bindweed, in contrast to the established elsewhere on the Rock Fill. " <br />There is no area of the Carbon Junction Mine designated as the "Rock Fill". From the <br />description and photograph it was deduced that you were referring to the Previously <br />Reclaimed Spoil Area (PRSA). Again, based on your photograph, the area described was <br />inspected on July 31, 2010. <br />No area of instability was observed. There was on evidence of potential slope failure, no <br />tension cracking, no slope bulging, no displacement of vegetation, no seeps or springs. In <br />short, there was no evidence of any potential or actual instability (Figures 2 and 3). <br />For several reasons the likelihood of slope instability in the area you described is <br />minuscule. The PRSA was created from shot durable rock sandstone with an engineered <br />French drain to remove any moisture from the fill. The fill material above the durable <br />rock sandstone is a homogenous mix of compacted porous colluvial overburden and <br />aggregate, covered with topsoil. The potential for water retention in such an engineered <br />fill is essentially nil. Certainly, the slope angle of the area you describe is insufficient to <br />generate an unstable slide mass. The presence of field bindweed, an opportunistic early <br />seral stage herbaceous perennial with any extremely broad ecologic niche is not <br />indicative of any slope instability, or of any significant condition. <br />In Section III, Comments-Compliance, under the heading, Excess Spoil and Development <br />Waste you state, "Adjacent to the northeast side of the Rock Fill, there is an area <br />(perhaps % acres in size) which appears to pond water on a seasonal basis (Photo 4). <br />The ground was dry at the time of the inspection, but vegetation differences (foxtail and <br />weeds) and remnant wildlife footprints provide clear indication that ponding does occur. <br />There exists the possibility that water ponded here is contributing to the toe bulge <br />described in the preceding section. Continued monitoring of the Rock Fill is warranted. " <br />There is no area of the Carbon Junction Mine designated as the "Rock Fill". From the <br />description and photograph it was deduced that you were referring to the Previously <br />Reclaimed Spoil Area (PRSA). Again, based on your photograph, the area described was <br />inspected on July 31, 2010. <br />Carbon Junction Mine Page 2 <br />CDRMO July 2, 2010 Inspection Rebuttal