A qualitative geophysical assessment was undertaken for Clarence Valley Council as part of the conception stage for an under bore in the Orara river.
Due to steep terrain and pristine water conditions, no boreholes could be undertaken in the riverbed. Potential complex issues were identified by boreholes undertaken for the project on top of the riverbank (100m away from river on either side) that suggested the area was unsuitable for under-boring. Contractors were therefore reluctant to provide a costing for the under bore due to unknown geological risk.
Aquares for land data was collected at the site including river banks and river bed. When combined with the boreholes in a ground model, it demonstrated the continuation of the complex geological risks under the river bed proving the under bore would be complex and expensive.
Council elected to undertake alternate methods for crossing the river. Without the ground model, the project would likely have gone ahead at high cost due to risks, particularly frack-outs or excessive leakage of drilling muds to the environment.
Environmental benefits: A potentially high risk project was not undertaken that could have created damage/ issues in the Orara River.
Economic benefits: If the project had gone ahead, cost overruns for the project were likely to be significant.
Social benefits: Protection of the waterways and cost savings also provide social benefits.