2010-12-16_PERMIT FILE - C1982056

Home Browse Search

Twentymile Coal Company 18 LT Utility Borehole — Drilling October 27, 2010 GENERAL SCOPE OF WORK The project scope of work to be completed by the Contractor shall include a 60' long, grouted, 16" diameter conductor casing. The utility borehole shall be drilled to a nominal 14 -3/4" inch diameter to a depth of approximately 1390 feet below the surface. Two steel pipes are to be placed inside the nominal 14 -3/4" drilled hole from the surface to the mine opening. One pipe will be a schedule 80, welded joint, 8 -5/8" diameter pipe. The other pipe will be a schedule 80, welded joint, 4 -1/2" diameter pipe. TCC shall provide the welded joint pipes. The work site should be available on or about 11 /15 /10for drilling. All permits should be secured by this date. General Provisions 1. Technical questions should be addressed to Michael Berdine at (970)- 870 -2782. 2. Contractor to provide a detailed, itemized bid on all aspects of this scope of work the Contractor intends to perform. TCC prefers a complete packaged bid from each Contractor. 3. Contractor to provide time line for completion of work outlined in this document. 4. The work site should be available on or about 11 /15 /10for drilling. 5. The winning bidder will receive a "not to exceed" amount Purchase Order. 6. Contractor must maintain all equipment and materials on the provided pad, including drill cuttings. Drill cuttings can be pumped to existing cuttings pit via a pipe line to be supplied by the drilling contractor. 18 LT Utility Borehole The 18 LT utility borehole is to be drilled approximately 1,390 feet in depth. The Contractor is to complete this borehole within a maximum horizontal deviation of 2.0% of the borehole length. It should be noted that the strata in this area dips at approximately 5% O the north. The surface drilling location has been selected to account for the anticipated up -dip walking of the drill bit to allow for aximum opportunity to intersect the mine workings. Two existing 18 LT boreholes were drilled in 2009 to a depth of approximately 1,390 feet and deviated approximately 25' to the north. The borehole will be intersecting open and examinable mine workings. The Contractor is to use an existing collections pit to collect the drill cuttings. TCC has prepared the pad for the drilling equipment. The Contractor may not extend or modify the pad without TCC's consent. Contractor is to install and grout a 60' long, 16" diameter, surface conductor casing or a size as deemed necessary for Contractor's equipment and to meet the borehole accuracy requirements. The Contractor shall then drill a nominal 14 -3/4 inch borehole into the surveyed mine roof (approximately 1,390 feet total length). Two steel, welded pipes are to be placed inside the nominal 14 -3/4" drilled hole from the surface to the mine opening. One pipe will be a schedule 80, welded joint, 8 -5/8" diameter pipe. The other pipe will be a schedule 80, welded joint, 4 -1/2" diameter pipe. Both pipes are to be fully grouted to within 3 feet from the surface. The Contractor shall provide a minimum of two grout basket on each of the two pipes, for facilitating grouting off the pipes, one placed 10' above the mine roof on each pipe and one placed 20' above the mine roof on each pipe. The 14 -3/4 inch drilled borehole should allow sufficient room to perform tremmie -pipe grouting from the bottom, up. Each pipe shall have a coupler and plug welded /installed on the bottom of the pipe string and shall be filled with water prior to grouting the annulus. Contractor shall air lift out the water from within each casing pipe after the concrete has set around the annulus. Attachments: 1. Exhibit A Location Map 2. Exhibit B Typical Lithology • 18 Left Utility BH Sscope of Work 102710.doc 10/27/2010 Page 2