Northam Platinum Mine – No 1 shaft – Transvaal RSA, 1989
During November 1988 the sinking crew at No. 1 Shaft reported intersecting water in a pilot hole at 4 level plat development. Attempts to pump cementitious grout via a telescopic packer proved unsuccessful. Drilling of additional pilot holes, together with the grouting program, fractured the surrounding rock so that what was only an intersection in a pilot hole subsequently became a general breakout through numerous fractures in the face and side-wall. Water inflow increased to 850 liters per minute, and water temperature was 55° C which was 2° C higher than the virgin rock temperature in the area.
In view of high hydrostatic pressure (17 MPa), the relatively weak tensile strength of the rock (14 MPa) and proximity to the face, it was decided to install a more remote seal closer to the source of the water. Numerous holes were then drilled into the fracture and grouted, but flow velocities within the water-bearing fractures were simply too high for emplacement of an effective cement grout seal.
During January 1989, Sovereign was contracted to seal the water ingress. Three strategically placed holes were drilled. Dye testing was performed to confirm adequate connection with the water-bearing fractures. SCEM66 with activator was injected, and the sealing operation was successfully completed within a single 8-hour shift.
