Laserfiche WebLink
• The borehole was drilled by a local drilling contractor using a Central Mining Equipment (CME) <br />model 55 drill rig. A 4-inch solid auger was used to drill through the colluvium/alluvium <br />material. Two Standard Penetration Test (SPT) drives were taken within this material using <br />standard American Society for Testing and Materials (ASTM) methods, including a 2-inch <br />outside diameter (O. D.) split-spoon sampler and 140 pound (Ib) drop hammer. <br />Appendix A shows the log for this borehole. The drilling confirmed colluvium/alluvium depths <br />of approximately 18 feet. The material classified as a silty sand with laboratory analyses on <br />material taken from split-spoon samples. Maximum particle size was 1.5 inches. The contact <br />with competent Rollins Sandstone bedrock is at 18 feet. The hole was continued to 75 feet <br />to confirm sandstone bedrock continuity. Drilling within the competent sandstone was <br />performed using a 4-inch rotary tricone bit. Water was used to circulate cuttings to the <br />ground surface where they were logged. Since the groundwater depth could not be <br />determined because of the use of water in the drilling process, a 1.5-inch diameter piezometer <br />was installed with screen in the bottom 50 feet. Several weeks later, the water level within <br />the piezometer was at 50 feet below the ground surface. This reading may, however, reflect <br />drilling water. <br />A geologic strata that was not encountered in the drilling program was shale within the Bowie <br />Member. This shale strata is located between the sandstone outcrops above the site (also part <br />of the Bowie Member) and the RoNins Sandstone below. Operations of the Sanborn Creek <br />Mine take place within this shale, and is believed to be located below the surficial colluvium, <br />topographically between the vertical Bowie Member sandstone cliffs above and the Rollins <br />Member sandstone outcrops at the railroad tracks below. A geologic cross section is <br />presented on Drawing 95255-02. Shale strata located within the Bowie Member is described <br />as "grey shale with thin to thick lenticular beds of buff sandstone, and contains several coal <br />beds" (PBR, 1995). <br />• <br />96266/1424.RPT Coel Mine Weate Benk Deaipn for the Sanborn Creek Mina <br />October 1898 WESTEC, Inc. 4 <br />