Laserfiche WebLink
SHARtNON ~ WtL$ON, INC. <br /> <br />GEOTECHNICAL STUDY <br />SOUTH TAYLOR EXCESS SPOIL FILLS <br />RIO TINTO ENERGY AMERICA <br />COLOWYO COAL MINE <br />1.0 SCOPE OF WORK <br />This report presents the results of our geotechnical exploration and analyses, as well as our <br />geotechnical recommendations for the proposed South Taylor Excess Spoil Fills. Our work <br />included review of previous studies by others at the site, review of geologic maps and aerial <br />photos, subsurface investigation, laboratory testing, and stability analysis. We also reviewed <br />information provided by Rio Tinto Energy America (RTEA) regarding bedrock orientations <br />below the site and seeps/springs. <br />Our work was performed in general accordance with our proposal and with the September 14, <br />2005 edition of the Colorado Division of Minerals and Geology "Regulations of the Colorado <br />Mined Land Reclamation Board for Coal Mining" (CDMG Regulations, Reference 1). <br />2.0 PROJECT DESCRIPTION <br />The excess spoil fills discussed in this report are located in the South Taylor Area, adjacent to the <br />proposed South Taylor Pit (Figure 1). RTEA provided post mining topography which indicates <br />the locations and configurations for two permanent excess spoil fills, as shown on Figure 2. The <br />western fill will be located in the valley just west of the boxcut. The east fill will include a <br />temporary excess spoil fill that will be constructed on top of the permanent fill and then removed <br />at a later date. In addition, astand-alone, temporary excess spoil fill is planned to the east of the <br />east permanent excess spoil fill. The boundaries may vary as planning proceeds. <br />Section 1.04 of the CDMG Regulations (Reference 1) indicate that, for a site to be classified as a <br />"Valley Fill," the side slopes of the valley measured at the steepest point must be greater than 20 <br />degrees, or the average slope of the profile of the valley from the toe of the fill to the top of the <br />fill must be greater than 10 degrees. Based on the topographic information provided by RTEA, <br />the two excess spoil fill sites are classified as "Valley Fill." The out-slopes of the valley fills are <br />planned at a maximum slope of 3.8 horizontal to 1 vertical (3.8H:1 V). Cross-sections through <br />• <br />23-1-OI105-200-Rl.doc 23-1-01105-200 <br />