Groundwater modelling misses the mark


Now that water supplies in the Maules Creek area are running low, residents are questioning the impact of mining and the ability to improve water levels given the existing baseline data, the monitoring of mine water usage and the state governments regulatory processes.

The Maules Creek coal mine was approved with a series of conditions that required the development of groundwater management plans, the validation of computer modelling, the development of adaptive management triggers and response plans, and self regulation by the mine itself.

It is hardly a recipe for the early identification and resolution of problems without strong government oversight. Based on past experience with noise and dust, mine self-regulation is unlikely to work should anything threaten the mine’s operations and returns to it’s shareholders.

Unfortunately, the government itself is conflicted. At the same time as the mine was being approved and constructed, the Department of Water was being systematically gutted, with the removal of operational staff, technical experts and middle management, leaving only the licensing division and the politically connected senior management to “supervise” any complaints and then manage the fallout.

Now, as water levels decline, the regulatory regime will come under the microscope and it is important to note that the potential for groundwater impacts were raised strongly prior to the projects approval.

The Peer Reviewer of the Maules Creek coal mine groundwater modelling had serious doubts back in 2012.

“Using the MDBC guidelines checklist, the modelling is found to be deficient and/or lacking in the areas of calibration, verification, sensitivity analyses and uncertainty analyses – each to varying degrees.”

“The primary risks of impact being assessed are associated with the alluvial systems yet the connection between the alluvial and bedrock systems in the calibrated model are not assessed to the previous studies and conceptual model to provide the reader with any confidence the model is replicating reality.

In fact groundwater specialists engaged by Maules Creek coal said exactly that on Page 62 of their Groundwater Impact Assessment;

“The model therefore simulates a continuous hydraulically interconnected aquifer system, which is not present in reality.”

Its inconceivable that the model didn’t represent reality raised no red flags for the miners, the Dept, the PAC and the regulators. The company simply paid another expert, as did the PAC, to confirm that everything was OK.

The Peer Reviewer for the local community gave a foretaste of the situation at the Werris Creek coal mine (and potentially at the Maules Creek mine) whereby the miner points to the results of their deficient theoretical groundwater model while blaming “the drought” for dry bores, while the mine pits are flooded with water. The Peer Reviewer lamented back in 2012 that the Groundwater Impact Assessment did nothing to assist with accountability should a groundwater problem arise.

“A clear method for identifying mining related loss of well yields from background yield losses should be defined up front to eliminate any confusion or difficulties after the fact.”

However it is this same deficient theoretical model which is now being use to regulate the mine 5 years later and it is time that the assumptions that were used are tested.