Laserfiche WebLink
cat <br /> Mining Corrx)raiior <br /> 1.0 Introduction <br /> This report presents the results of a geotechnical investigation performed for a section of <br /> the existing access road at the May Day Idaho Mine Complex located on County Road 124, <br /> Hesperus, La Plata County, Colorado (Figure 1). This investigation was performed to evaluate <br /> its stability and provide criteria for design of planned improvements, and in fulfillment of <br /> requirements for additional geotechnical investigation activities and recommendations as <br /> described in the Colorado Division of Reclamation, Mining, and Safety sixth adequacy letter <br /> dated September 30, 2011, and the Colorado Mined Land Reclamation Branch's 112d-1 Permit <br /> approval, dated December 12, 2011. <br /> The scope of work included reviewing documents related to access road design and <br /> construction, including the results of previous geotechnical evaluations, performing a subsurface <br /> investigation and field and laboratory testing and engineering analyses to develop criteria for <br /> design of access road improvements, and preparation of this report. <br /> 1.1 Existing Access Road Description <br /> An access road was constructed in 2008 to provide access to the mine areas, and extends <br /> from County Road 124 to the La Plata River Bridge, approximately 2,700 feet long (Figure 2). <br /> The focus of the investigation is the area from Stations 15+00 to 27+00, which consists of three <br /> sections: the upper portion extending through a through-cut between Stations 15+00 and 16+50, <br /> a cut-fill condition and a fill embankment crossing a drainage between Stations 16+50 and <br /> 21+00, and flat section in native soil between Stations 21+00 and 27+00. <br /> The existing roadway slopes average less than 15 percent but vary from less than 2 <br /> percent to slightly over 23 percent. Roadway widths are over 20 feet wide between Station <br /> 15+00 and 18+00, between 15 and 20 feet wide between Station 18+00 and 19+00, and less than <br /> 15 feet wide thereafter. Cut slopes vary from slightly flatter than 1:1 (Horizontal: Vertical) <br /> between Station 16+00 to approximately 0.7:1 at approximately Station 18+80. <br /> 2.0 Investigation <br /> This investigation included a literature review and performing a subsurface exploration <br /> program. Documents reviewed include published references on regional geology, and the results <br /> of previous investigation, including the following. <br /> • Sakura Engineering, Geotechnical Reconnaissance of Idaho Mine Access Road, <br /> November 2008 <br /> Wildcat Mining Corporation <br /> 112(d)Permit—May Day Idaho Mine Complex <br /> Wildcat Mining Corporation,3926 N.State Highway 67 <br /> Sedalia,CO 80135 Office: 303.832.7664 <br />