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UNDERGROUND DRILLING The GMP Vertical Rod Pusher frees up geotechnical drills, such as the one shown here, from survey tool deployment assignments. GMP built a prototype specifically to meet the needs of Cigar Lake's unique application. This first prototype needed only one modification: For use in the mine, GMP replaced the gasoline engine driving the hydraulic power pack with a 600- volt electric motor. Loehr also had GMP supply a ½-in. Duct Rodder (in its normal cassette) and the Portable Powered Duct Rod Pusher without its carriage. Cameco would fabri- cate a frame for mounting the power pack and pusher (also referred to as the drive head). Once the GMP equipment arrived at the mine, additional modifications were made in preparation for underground ver- tical borehole testing, including a skid to which the power pack and drive head were attached, and a cage that con- tained the Rodder and cassette. After the preliminary work was completed, the Portable Powered Duct Rod Pusher was put to the test. The first trial sent a bare rod (without tool weight) up a 258-ft-long, 3-in.- Results of original, simulated tool-weight test results for the rod pusher in a mine environment. diameter, near-vertical borehole. The machine easily pushed a distance of 252 ft under those conditions. After that, different simulated tool weights were added and the results were meas- ured for each test. Testing conducted with a standard ½-in. rod proved sufficient to deploy simulated tools of various weights to distances of 137 to 252 ft. This satisfied the deployment requirements of several existing survey instruments. But the tests also exposed issues concerning the stiffness of the fiberglass rods; they were bending, snake-like, from tool weight and self-weight, thus creating friction against the inner wall of the borehole. Because long-term applications would require deployments into even larger (up to 5-in.) boreholes, "we needed to solve the serpentine problem," Young said. To achieve the desired distances and borehole diameters without rod deflection, GMP provided a thicker, stiffer 5/8-in.- diameter fiberglass rod. However, the thicker rod required a much larger storage cassette. GMP fabricated this to accom- Vertical Rod Pusher and electric hydraulic power pack mounted on Cameco-fabricat- ed deployment frame. www.e-mj.com New 5 ⁄8 -in.-diameter rod cassette and cage. The cage is 8 ft square x 53 in. wide. NOVEMBER 2012 • E&MJ; 63