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1100318 R0T0 0811 JRW1 2 <br /> Exponent and various entities have identified potential alternate causes of the <br />December 2, 2008 landslide. As part of its scientifically rigorous analysis, <br />Exponent’s investigation evaluated the following potential alternate causes: <br />reported overly extensive excavation of Area H, previous over steepening and <br />poor rock quality of the west highwall, rainfall and high groundwater levels, <br />failure along bedding planes in the Manitou Formation, over excavation and <br />placement of fill on the west slope, and the fracturing of unextracted rock <br />from blasting. Based on the results of Exponent’s analysis, Exponent has <br />ruled out these potential causes as the cause of the December 2, 2008 <br />landslide. <br /> Permitted aggregate extraction in Area H is described in various documents, <br />principally including the 1994 Permit Amendment, 2000 Permit Amendment, <br />and Technical Revision 11. Based on the available documentation, the <br />designs described in these documents were substantively implemented at <br />Pikeview Quarry. <br /> Since December 2, 2008, Pikeview Quarry has experienced additional <br />episodic slope movements ranging in magnitude from relatively minor to <br />large. All post-December 2, 2008 slope movements are nested within the <br />landslide boundaries established on December 2, 2008. The movements did <br />not materially increase the damage caused by the December 2, 2008 landslide <br />or the inability to obtain saleable aggregate from the quarry. The additional <br />movements need to be taken into consideration in any reclamation plan; <br />however, they do not alter the scope of the reclamation plan required by the <br />December 2, 2008 landslide. <br /> The saleable aggregate on the west highwall and in portions of Area H at the <br />Pikeview Quarry cannot be obtained without stabilization of the west <br />highwall. The December 2, 2008 landslide rendered these areas unsafe for <br />further mining operations without stabilization of the landslide. <br /> A viable reclamation plan requires enlargement of the Permit Boundary by <br />approximately 10 acres to allow removal of the existing landslide and to <br />create a stable slope. Access to this additional 10 acres is a necessary