This paper discusses the development of a strategy for ensuring long-term geotechnical stability of final pit walls at AngloGold Australia's Sunrise Dam Gold Mine. The strategy makes use of improved blasting techniques, changes to the mining sequence and other geotechnical techniques. Only the blasting techniques will be discussed in this paper. These were developed from numerous trials over a period of several months from May 2003 through to November 2003. The focus was to reduce crest loss damage and thereby improve final wall integrity, maintain designed safe berm widths, and ensure long-term stability._x000D_
Crest loss mechanisms are now understood and are explained in this paper. The preferred solution is outlined; which is a combination of improved blasting and changes in the mining sequence to cater for pre-existing ground conditions._x000D_
These ground conditions include dynamic hyper saline water with sometimes intersecting steeply dipping discrete structures._x000D_
Project requirements were defined as mitigating or eliminating crest loss using 127 mm diameter pre-splitting and targeting minimal production blasting vibration levels against the walls._x000D_
Blast results were measured by post blast visual inspections and video. Blast design input utilised the predictive algorithms built into simulation software when attempting to minimise vibration levels against the walls._x000D_
Protection of the already fired pre-split line is now achieved using small charges against the wall and timing sequences which form a mask for the later firing main charges._x000D_
The pre-split spacing is now modified to suit the geology. There eight blast domains identified around the perimeter of the pit, each having varying joint orientation._x000D_
In addition, blasting the bench adjacent to the berm crest has particular considerations not required by the middle and lower benches. The preferred solution was to purposefully translate this damaged top section of the pre-split bench into a planned subsequent dig zone. The design of this top weight' is a direct response to the nature of the crest loss mechanism.