Pit-slope design is a specialised activity requiring anticipation of variable geological conditions and the application of engineering analyses. Greater levels of safety and productivity can be achieved if the knowledge of how pit slopes behave can be transferred to the operators at the coalface.

The video, Unearthing Black Gold was produced by the Australian Centre for Geomechanics with the script written by leading geotechnical consultants John Simmons of Sherwood Geotechnical and Research Services and Graeme Boyd of Minserve Group. The video was edited by mining company personnel from Rio Tinto, BHP Billiton Mitsubishi Alliance (BMA), HWE and Anglo Coal.

Ross Seedsman, director, Seedsman Geotechnics reviewed the package that consists of a 42 minute training video, and comprehensive training and language support materials.

“The script is written for the layperson, and uses high quality video footage from mining operations and excellent graphics to explain pit slope failure modes. The script moves effortlessly from explaining the hazards to identifying the warning signs and then the importance of controls that the workforce can implement. There is an emphasis on the importance of following the site’s procedures and controlling water,” Seedsman said.

The video is divided into eight parts, through definitions of terms, the mining cycle, general pit slope hazards, hazards in excavated rock walls, hazards during stripping, hazards in spoil and waste slopes, to hazards in coal stock piles.

In his review Seedsman outlined the content: “For excavated rock walls, the identified hazards are falls of isolated rocks, planar failure, wedge failure, toppling failure and composite failure. Computer graphics are used to illustrate each of these mechanisms. Failures of boxcuts and dragline benches are also included. The importance of good blasting practices, excavation to the design limits, wall trimming, water control, and following site procedures are all stressed.”

For spoil piles and waste dumps, the hazards are rolling of isolated rocks, skin slippages and deep-seated slips. The role of poor floors, weak base material, weak spoil material, dumping into water/mud and control of surface water are all mentioned. Monitoring systems are introduced in this section, on the basis that the deep-seated slips are usually the slowest moving and hence the easiest ones to monitor. Hazards associated with the construction of stockpiles and waste dumps and reclamation of coal stockpiles are covered.

Seedsman cited a quote from the video: “We can’t rely only on monitoring systems. The eyes and ears of a committed workforce are the most valuable assets mines have for monitoring hazards” adding he was in total agreement

“Recently there has been too much emphasis on monitoring in the guise of risk management, almost to the exclusion of the fundamentals of good design and the hazard reduction potential of a trained and committed workforce. Unearthing Black Gold will assist in achieving the latter,” he said.

For further information please contact Josephine Ruddle at the Australian Centre for Geomechanics via acg@acg.uwa.edu.au.