Mt Arthur Coal extension included a cut-off wall installation up to 14m below ground level through think layers of poorly graded river gravels. Read how Keller achieved a permeability requirement of less than 1 x 10-9 m/s.
As part of Mount Arthur Coal (MAC) Windmill Extension works, Keller were engaged to constructed a soil bentonite cut-off wall to minimise potential ground water movement into the proposed mine expansion. The cut-off wall was approximately 900m in length and was required to socket into bedrock at depths of up to 14m.
The ground conditions comprised a thick band of river gravels at depth and some cemented layers above the bedrock. In some locations the gravel band was 6m thick and comprised cobbles up to 100mm raising concerns for excavation stability.
Keller performed a number of mix design trials to overcome the complicated ground conditions and to ensure the performance criteria was achieved. The team utilised a custom cut-off wall bucket to penetrate through the challenging ground conditions to complete the wall with zero incidents, on time and within budget.