A series of questions were posed at the start of the day, for which 120 attendees were registered:
- Are hazard management plans an appropriate way of managing safety?
- What is the role of risk assessments?
- Have we identified the hazards?
- Do the plans manage the hazards?
- Is there too much emphasis on monitoring and not enough on the design stage – in particular mine layouts?
- Can the plans be implemented?
- Are they implemented?
Ten papers were presented ranging from the identification of geotechnical hazards in both development and longwall, through risk assessments to implementation. Case studies were presented from Crinum, Kestrel, Dartbrook, BMA Goonyella/Riverside, and Gibson's Mines.
The issue of rib stability was raised several times. John Shepherd summarised work done over the last 20 years, and commented that there is little recent work. The NSW Inspectorate quoted recent figures that suggest that two-thirds of ground injuries and fatalities are related to falls of ribs. Is there a connection?
The role of risk assessments was discussed with the emphasis that they are not a replacement for geotechnical engineering. Some considered that the strength of risk assessments is the forum where risks can be identified - others suggested that too much time is spent on identifying risk and not enough on controls. Clearly there are different applications of risk assessment techniques.
The Queensland case studies indicated what can be done when there is a large body of exploration data - drilling and 3-D seismics. These papers showed how to integrate the data into the underground operation. The Kestrel case study discussed the way the mines at the face are part of the information gathering in preparation for longwall retreat. At Crinum the exploration data is used to change primary and secondary support on development. The BMA Goonyella case study showed what can happen when geological structures are encountered that even the best exploration cannot detect.
The discussion session, led by Ian Anderson, covered similar ground to the previous day - how to train engineers in the art of ground control and geotechnical engineering. A common theme was the need for guidelines to what is a good strata management plan. Three of the conveners of the conference are three geotechnical consultants so there was a particular interest in their role in a strata plan.
Ken Singer quoted some statistics from the United States where the data shows conclusively that it is experienced miners in new mines that are at risk. There is no reason to think that this is not the case in Australia. Strata plans will only be a success if they can identify hazards in new ground and then change the behavioral patterns of the workforce. The conference dealt with the first point – substantial progress is being made in anticipating hazards. Progress in modifying behaviours at all levels - management, planning, operational - is perhaps slower.
The colloquium was run in associated with the AusIMM Illawarra Branch, the NSW Coal Mine Manager’s Association, the Gas and Coal Outburst committee and The University of Wollongong.
