Tulloch has completed a number of surveys for the mining industry to provide alignment for raise bore hole drilling. Advances in drilling technology have translated into an increased use of this method for opening up holes between surface and underground mine to provide air to the mine or to be used to deliver ballast such as sand into the mine. Recent raise bore alignment surveys have been completed at Totten mine and Frood Stobie mines where some of the raises are up to 3000 feet in length between surface and the underground.

The mining company provides Tulloch with their design coordinates, usually in a local mine coordinate system, for the point on the surface and the point underground. The surface point is laid out first and a poured concrete pad is constructed to secure the boring equipment. Tulloch then provides alignment direction (azimuth and dip) for the drill set up to ensure the correct orientation to hit the planned break through point. Once the boring rig is positioned based on the initial layout the survey crew returns to precisely align the boom of the rig to match the design alignment. The boom of the drilling equipment can be up to 25 feet long so the alignment is critical (a ¼ of an inch of misalignment of the boom can make a significant difference in a 3000 foot long drill hole).

A pilot hole usually 12” to 15” in diameter is drilled from surface to the underground break through point. Often a directional gyro survey of the pilot hole is completed to confirm that the hole is advancing along the design alignment. The gyro provides the measured azimuth of the hole related to magnetic north so a baseline is generated by Tulloch to provide a relationship between north and the local mine coordinate system. Once the drilling of the pilot hole has been completed, rods are installed from surface to connect the raise bore rig with a cutting (reaming) head underground. Raise drilling begins as the boring rig pulls the reamer towards surface along the pilot hole. The final raise can range in diameter depending on the purpose but can be many feet in diameter if being used for fresh air delivery to the mine or only a few feet if being used as a backfill hole.