AGL has been cleared of BTEX use in a recent investigation of flowback water from AGL’s Waukivory Pilot Project near Gloucester (NSW).
On 27 January 2015, AGL Upstream Investments Pty Ltd reported elevated levels of BTEX chemicals in a water sample from one of its wells.
Operations were voluntarily suspended while further samples were taken from the three other wells and separate investigations by the Division of Resources and Energy (DRE) and the Environment Protection Authority (EPA) began.
The NSW Government bans the use of BTEX chemicals in the fracture stimulation of coal seams because of their potential danger to human health if they occur in high enough concentrations for prolonged periods of time.
The DRE investigation looked at a number of factors including AGL’s fracture stimulation methods, its surface and groundwater plans, its water sampling methods and the geology of the Gloucester Basin.
The region contains extensive coal deposits in ancient formations that hold traces of oil. Investigators could find no evidence that BTEX had been used by AGL in any fracture stimulation fluid or drilling process.
The evidence gathered during the investigation found the source of BTEX in the flowback water is from naturally occurring groundwater within the deep coal seams which are in excess of 600m below the surface.
There is widespread independent literature confirming that BTEX can occur in groundwater found in deep coal seams with similar geological formations.
There is no evidence of BTEX being detected in aquifers close to the surface. The DRE findings were sent to the University of Queensland for independent review by specialist researchers who reached the same conclusion of naturally occurring BTEX and they reported that fracture stimulation activity did not impact the water quality of the shallow aquifers.
With the investigation now completed and no adverse findings, AGL is entitled to resume operations.
The company has an application to change the manner in which flowback water is disposed of and that application is currently under consideration by the relevant agencies.