Protecting and understanding local water resources is a critical part of the sustainable development of AGL's coal seam gas operations.
The Camden Gas Project groundwater investigation and monitoring program was developed by AGL and environmental specialists, Parsons Brinckerhoff, to help the community understand what impacts, if any, there might be on groundwater resources as a result of exploration for and production of natural gas.
The monitoring program involves dedicated monitoring bores that monitor the groundwater in the shallow aquifers within the Camden Gas Project and at a control site away from the Project.
The completed and planned work investigates connectivity between the shallow groundwater aquifers and water bearing zones in the coal seams. Two key findings of the work to date indicate negligible or no connectivity: the shallow groundwater is chemically different from the deeper coal seam groundwater, and flow within the groundwater systems appears to be mostly lateral, rather than vertical.
Only very small volumes of water are released from the coal seams and in the 2013/14 financial year it was less than 3.6 megalitres for the entire Camden Gas Project (which is about one and a half Olympic swimming pools). This small volume of produced water provides further evidence that there is no or negligible connectivity between the coal seams and other groundwater systems – that is, the water removed by AGL's activities is from the coal seams and not beneficial aquifers.
Access and download previous results from the groundwater monitoring program, in our document library.
AGL hydrogeologist checking one of the water monitoring bores at our Camden Gas Project.
The Camden Gas Project Groundwater Management Plan provides a framework for early assessment of any changes in the groundwater systems beneath the Camden Gas Project area, particularly to the shallow beneficial aquifers. Monitoring and early identification enables us to prevent and/or mitigate any adverse impacts. This plan outlines the monitoring program and reporting requirements to regulators.
Produced water is natural groundwater that is removed from the coal seams (which are approximately 700 metres below the ground) in order to allow the natural gas to flow. AGL analyses produced water quality from a selection of operating gas wells each quarter, as described in the Groundwater Management Plan. The monitoring results are available in the document library and on the Monitoring Data page.
In 2011 and 2012, AGL’s water quality monitoring program found the produced water from some gas wells had significantly lower levels of salt than expected (at a level similar to rainwater or river water) and also a different ratio of the type of salts than is typical for coal seam gas wells at the Camden Gas Project. AGL wanted to understand why.
After conducting internal investigations, AGL engaged Parsons Brinckerhoff to investigate the lower salinity of produced water coming from some gas wells and to provide reasons why this was happening. Following expert chemical and isotope analysis, Parsons Brinckerhoff found that the low salinity water does come from the coal seam but it has been physically and chemically changed due to changes in pressure and temperature. The results from this investigation are very important in continuing to build on our comprehensive understanding of groundwater, produced water and coal seam gas operations for the Camden Gas Project. Download the 2013 Parsons Brinckerhoff report and summary.
As part of its coal seam gas exploration and production programs in NSW and QLD, AGL Upstream Gas commissioned a desktop study on the occurrence of naturally occurring hydrocarbons in groundwater from Permian coal measures and associated sedimentary rocks. The report, prepared by CSIRO, Earth Science and Resource Engineering - Petroleum and Geothermal Research Portfolio Group, concluded that most of the detected total petroleum hydrocarbons, PAH (polycyclic aromatic hydrocarbons) and BTEX (benzene, toluene, ethyl benzene and xylenes) compounds appear to be naturally occurring.
Similar to a drinking straw, a monitoring bore lets us find out what is happening with groundwater. We drill a hole into the ground and install a sealed pipe that has tiny holes at the bottom to let groundwater enter the pipe. The groundwater rises up the pipe to a water level that reflects the water pressure in that aquifer where the bore is installed.
We often put several monitoring bores next to each other, installed to various depths, to monitor groundwater in different aquifers or groundwater systems. We can then measure the water level and water quality in each of the bores to see how they relate to each other and how they change over time.
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