Review of groundwater modelling at Carmichael coal mine
Issued: 3 Mar 2023
Bravus has committed to undertaking further groundwater modelling at its Carmichael coal mine to ensure the early detection and prevention of any potential future impacts to the Doongmabulla Springs Complex.
The commitment comes after the Department of Environment and Science (DES) received a groundwater model report from Bravus about its predicted impacts at the mine if underground mining were to commence as planned post 2034.
The report was produced under a requirement of their Environmental Authority (EA).
Importantly, based on a preliminary review by DES, the report indicates there are no predicted impacts to the springs from current and future open cut mining.
However, the report indicates there may be impacts to the springs from future underground mining under the current approved mine plan. It demonstrates underground operations will result in a predicted drawdown which is not consistent with approved impacts.
Bravus has committed that it will not proceed with its underground mine development until the completion of investigations and assessments which demonstrate and conclude that further development will not exceed approved impacts.
DES has issued Bravus an Environmental Protection Order which requires that:
- Bravus undertake a second groundwater model re-run and provide a report to DES.
- underground mining not commence until a second groundwater model review report is approved by DES.
The department recognises the significant cultural and environmental values attached to the Doongmabulla Springs Complex and is committed to ensuring the highest protection is afforded to the springs.
The department is continuing to review the current report and has sought advice from CSIRO and Geoscience Australia. The department has directed that any feedback from this review must be incorporated into Bravus’ next report.
Background
The conditions of the Bravus EA were designed based on an adaptive management approach. This means conditions of the EA were developed requiring regular re-runs of the original modelling over time using real data collected since mining commenced.
The aim of this approach is that as research and monitoring information becomes available, the model is refined and uncertainty is reduced.
This results in a more accurate model, ensuring the early detection and prevention of any potential future impacts to the Doongmabulla Springs Complex due to mining operations.
Adaptive management also provides the opportunity for an operator to modify its mining activities where necessary to mitigate those impacts.
DES has received the first groundwater model re-run report from Bravus about its predicted modelled impacts at its Carmichael coal mine.
The next model re-run Bravus is required to undertake in accordance with its EA is due in 2027, six years prior to commencement of underground operations. However, based on the results of the first re-run, Bravus has committed to undertaking a re-run sooner.
DES has now formally required Bravus to complete a second re-run and provide an updated report later this year. The department has directed that any feedback from the CSIRO and Geoscience Australia must be incorporated into the second model re-run.
The department has also included a requirement that underground mining not commence until the completion of investigations, assessments and modelling that concludes impacts will not exceed the approved drawdown and the re-run report is approved by the department.