GFWAust were appointed to grout up the annulus around a leaking pipe on the new South out-of-pit Water Dam 

Mt Thorley Warkworth mine is part of Rio Tinto’s Coal Division and is located near Singleton in NSW. As part of the overall water management system on the mine a new South out-of-pit Water Dam was constructed. The works included the construction of an embankment and sedimentation dam and were carried out by Robsons Civil.

The out flow from the dam was via a 100m long, 710mm diameter HDPE pipe that was encased in concrete. During commissioning of the works there was found to be a leak of 60L/min from around the pipe through a small annulus formed in the concrete encasement. Further leakage of around 15L/min was also noted through the coarse aggregate above the encased pipe.

GFWAust were appointed by the designers ATC Williams to grout up the annulus around the pipe and stop the leak.

Injection ports and bleed ports were installed at the bottom end and top of the encased pipe and following a simple water test, GFWAust injected a thin, low viscosity precision grout which would not bleed or shrink. Grout pressures were monitored and kept to a minimum to ensure no distortion of the pipe. The pipe was filled with water to assist with adequate cooling of the grout during curing.

The works were completed successfully and quickly allowing commissioning of the dam to be completed and regain some lost program of the works.