Mine Pit Lakes Study will bring certainty

Initiated by ChemCentre, Mine Pit Lakes – Their Characterisation and Assessment for In-Situ Metal Recovery Opportunities and cost effective environmental management is a three-year collaborative project involving  ChemCentre, CSIRO, MBS Environmental, the Department of Mines and Petroleum, Department of Water, and Department of Environmental Regulation. The project is funded by both the Corporate Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE) and the Minerals Research Institute of Western Australia (MRIWA).

Project leader Dr Silvia Black (ChemCentre) said the project aims to better inform and validate existing predictive geochemical models by obtaining ‘real world data’ from existing mine pit lakes and mine pit voids.

“When mining has finished, the pit that remains often fills with water, either from natural seepage or from rainfall,” Silvia said. “There is a potential for metals from the walls and floors of the pit to become mobilised and leach into the water. We want to understand the conditions under which metals mobilise into mine pit lakes and when that mobilisation matters.

“For example, there may be heavy metals such as chromium in the leachate, and this may have long-term implications.

“If a pit lake is forming in a remote area, contaminants could potentially impact wildlife and the food chain. Where mining occurs close to communities, pit lakes could potentially affect groundwater supplies. Correctly managed, these lakes could have recreation potential if potential long-term environmental impacts on water quality are well informed.

“Our study will provide real world data to better inform predictive models.”

Silvia said that while predictive models are applied to understand the long term environmental impact of mine pit lakes, some assumptions are made due to gaps in the available knowledge to inform the predictive models.

“Very little real world data has been collected, simply because it’s a very expensive research exercise” she said.

“We now have an opportunity to do the science to minimise the need to make assumptions about what is likely to happen in mine pit lakes after mining has finished and make confident predictions extending, for example. 100 years into the future.”

A key outcome of this project will be a laboratory based ‘decision support’ tool to better predict the leaching potential of waste rocks that will ultimately constitute the walls and floor of mine pit lakes.

“We hope that the tools we are able to develop through the project will be used by government and industry to enable Western Australia to move forward with exceptional mine planning and environmental approvals processes,” Silvia said.

“We will be involving industry and government regulators in the project to ensure we remain focused on meeting their needs.”

ChemCentre provides expert chemical analysis and expertise to help the Western Australian Government deal with potential chemical risk while enabling appropriate state development.