Published in March 2006 Australian Longwall Magazine

In the future, water issues could affect a mine’s ability to gain mining approval where significant aquifers are involved, for instance.

According to Dr Hua Guo, CSIRO Exploration & Mining’s mining systems research leader, the interaction between ground conditions and water in mining is not understood in an integrated way.

“Taking an integrated approach involves geological and hydrogeological site characterisation, pore pressure monitoring, flow measurements, and overburden fracturing and subsidence monitoring,” he said.

Such an integrated approach is the subject of a new ACARP-funded project aimed at developing a mining hydrogeological response assessment and prediction methodology for the coal industry.

The project, to investigate the effects of longwall mining on water flow, aims to advance the understanding of fundamental mechanisms of strata and groundwater interaction. This in turn will facilitate prediction of water inflows into longwalls and mining-induced interference with aquifers. The proposed approach is the first of its kind in Australia.

The major benefit of the project is to provide the coal industry with a sound and practical site hydrogeological assessment methodology.

Eventually, this will be used as a mine-planning tool to predict mining aquifer interference, ground water inflows and barrier size requirements. Mines will be able to design appropriate pumping capacity, which will ultimately result in reduced mining risks and higher productivity.

The project will focus on Centennial Coal’s Springvale Colliery, the site of earlier CSIRO research into water.

In 2004 and 2005, Guo led research at Springvale that identified the operation would have to manage up to 25 megalitres of water per day by 2015. That work resulted in options being developed for water discharge to a nearby power plant for use in electricity generation.

The new work will monitor surface and underground hydrogeological and overburden movement.

The various monitoring, measurement and 3D modelling results will be cross-correlated to establish a hydrogeological response model of longwall mining.

The project uses CSIRO’s proprietary COSFLOW software code as one of the key tools. COSFLOW has been used to assess mine subsidence, ground water inflow and gas emission and drainage at the Appin, West Cliff, Springvale, Central and Wambo mines as well as the Xieqiao and Zhangbei mines in China.

The new project will play an important part in improving the understanding of mining-induced hydrogeological impact.

Guo said other mines had indicated support for the project, adding that CSIRO is also in the process of recruiting a hydrogeologist to support ongoing research work in this important area.