An independent analysis has found serious flaws in the modelling and reporting by an open cut coal mine adjacent to landholders who have lost, or have dramatically reduced groundwater supply. Initial modelling of the mine estimated a 10cm drop in bore levels, but data now shows an average 4m drop in the affected area. As a consequence of the findings the NSW DPI Office of Water has commissioned a review into what has become known as the “Werris Creek matter”.

After concerns raised by landholders above the Quipolly Creek alluvium aquifer were largely dismissed by Whitehaven Werris Creek mine and DPI Water only had the resources to review the reporting of groundwater take by Whitehaven against their licence conditions, Caroona Coal Action Group Inc. (CCAG Inc.) and the local landholders commissioned an independent assessment of the changing groundwater conditions to the south of the Werris Creek Mine.
The report, by the University of NSW Australia Water Research Laboratory, found that groundwater in the basin, which previously flowed south, now appears to be flowing north back towards the mine workings. The assessment also points out that removal of the overburden to reach the coal seam has resulted in depressurisation of the underlying aquifer system which also appears to have not been properly taken into account. The investigation also finds incomplete water-balance accounting practices which are not suited to predicting water levels of the landholders’ wells and bores, hence the review by DPI Water. Despite assurances by both DPI Water and the mine itself that the loss of water in landholder bores was due to drought conditions, the report concludes that “it is likely that coal mining operations at WCC’s Werris Creek Mine are contributing to the impacts currently being observed at landholders bores.”

DPI Water, the regulatory body overseeing the water management at WCC, hadn’t completed hydrogeological assessments of the reported groundwater declines to fully understand the observations and check for oversights in the groundwater modelling due to resourcing. These assessments must be part of the mining conditions, done regularly and by an independent and qualified hydrogeologist. DPI Water must be given the resources to ensure this is done.
Chairman of the Caroona Coal Action Group Inc., Susie Lyle, says: “The implications of these findings are very significant for the proposed Shenhua mine at Breeza. When considered in conjunction with the recently published technical article by Ian Acworth and associates, illustrating that current groundwater models used to consider the consequences of extractive industries on the Liverpool Plains contain gross simplifications and inadequate field data regarding vertical aquifer connectivity, Federal and State Governments must review their decisions in relation to the Shenhua mine.”
“The Werris creek mine is a fraction of the size of the proposed Shenhua mine, and the impacts potentially catastrophic on one of the most productive yet intricate underground aquifer systems in Australia.”