Laserfiche WebLink
INTRODUCTION <br />On May 4~", 1998 a geotechnical coring project core drilling project was initiated <br />at the Oxbow underground coal mine at Somerset, Colorado. The Montgomery <br />Watson (Terramatrix) consulting firm of Steamboat Springs was contracted to <br />permit a new underground entry for the Oxbow Mine. This entry is to access the <br />D-seam, located approximately 240 straligraphic feet above the B-seam currently <br />under development by Oxbow Coal's Sanborn Creek entry. <br />D.A. Smith Drilling of Loma, Colorado was contracted to undertake the core <br />drilling. Glenn E. Miller Inc. of Elizabeth Colorado was sub-contracted through <br />Montgomery Watson to administer the drilling and to geotechnically log the core <br />samples. <br />Three top to bottom geotechnical cores were to be taken along a projected entry <br />path into the D-seam. Particular attention was to be made of the burn areas. As <br />the project progressed, it became evident that the initial entry path into the D- <br />seam would be much greater in length to access the unburned coal. This <br />discovery led to the addition of 9 additional drill sites to check rock strength, coal <br />quality and hydrologic characteristics at other entry locations. <br />Field operations were completed on August 20th, 1998 with the demobilization of <br />the Smith Drilling Company drill rig. <br />DRILL COSTS if< PRODUCTIVITY <br />A total of 12 drill sites were completed during the project and a total of 3321 feet <br />were drilled. Of this footage, 2633 feet were cored. Overall core recovery was <br />2473 feet or 93.9°~ (Table 1). The invoice costs for the drilling were $153,779.29 <br />and took 79 operational days to complete. This was a productivity rate of 42 feet <br />per operational day. This low productivity figure was a direct reflection of the <br />unstable hole conditions encountered in the bum zones. The D.A. Smith <br />Company cost analysis tables are located in Section 2 and show a total invoice <br />cost of $46.82/drill foot. The individual day sheets for the project are located in <br />Section 5. <br />CORE HANDLING PROCEDURES <br />As a geotechnical project, the priority of the project was to collect core data, rock <br />mechanic and chemical samples of the floor, roof and coal portions of the D- <br />seam. <br />Continuous coring was the drilling method selected by Oxbow Mining due to the <br />size (3 sites) and shallow depths (<300') of the initial project. Core samples <br />would allow the direct observation of all strata above, through and below the D- <br /> <br />Page I of ~ <br />