Springvale and Angus Place lie adjacent to one another, approximately 15 kilometres north west of Lithgow in New South Wales. Together the mines supply five million tonnes of thermal coal to the local Delta Electricity’s Wallerawang and Mt Piper power stations.
Angus Place currently mines a block 250m wide, 3300m long and a working thickness of 3.2m. Springvale has similar conditions with blocks 255m wide, 1900m long and a working thickness of 3.25m.
Both Springvale and Angus Place mine plans and budgets are based upon production model assumptions used to forecast ground conditions and corresponding roof support regimes.
According to mine general manager Bob Miller the structural model has been a highly successful hazard prediction tool compiled by integrating geophysical interpretations with factual geological observations.
There has been ongoing structural mapping of the seam and roof of the Lithgow seam in the development areas ahead of mining, as well as development and updating of a model for the structural framework of the Springvale/Angus Place area from regional aeromagnetic, gravity and remote sensing data.
Trial testing of closely spaced helicopter-borne magnetic data has been carried out to identify secondary structural features. Analysis of mapping during longwall mining is also carried out to gauge implications for future developments.
The results of underground observations are regularly reviewed against modeled structure zones to evaluate the success of the model. To date the success rate encountering mapable structures within the predicted structural zones is about 75% - a higher rate that any other predictive method used in the past.
“Prediction of future hazard areas likely to be encountered in development and/or longwall panel can be undertaken with a much higher degree of confidence and prior warnings provided to the operational crews – a fundamental aspect of the mines’ strata management plans,” Miller said.
The mines use the structural model to plan development advance and longwall retreat rates and in designing minimum roadway support requirements to match expected conditions.
Centennial has also taken advantage of existing synergies between Angus Place and Springvale. Improvement in the understanding of geological, geotechnical and hydro-geological issues along with combined learning experiences in roadway support, production equipment and coal clearance design has avoided duplication in work and resultant waste of resources.
