ABSTRACT
The ore body at the McArthur River uranium mine is located underground between the 530 m and 640 m development levels and is situated in a brecciated conglomerate zone along a fault with fractured, silicified sandstone above, and pelitic basement rock below and on one side. Water transport in the region is mainly through cracks and fissures in the sandstone and the water pressure is hydrostatic to the surface (i.e., approximately 5500 kPa). In order to prevent high-pressure water flows during mining, it has been necessary to artificially create a frozen wall barrier around the perimeter of the ore body. The geology of the ground that the freeze pipes pass through is not consistent. Many of the 105 m long freeze pipe holes are drilled through rubble, flowing sand, and squeezing clay zones, ending up in hard basement rock. This paper focuses on the need for ground freezing and the challenges associated with installation of the freezing system.
