Year

2014

Degree Name

Bachelor of Science (Honours)

ANZSRC / FoR Code

0401 ATMOSPHERIC SCIENCES, 040203 Isotope Geochemistry, 0406 PHYSICAL GEOGRAPHY AND ENVIRONMENTAL GEOSCIENCE, 040603 Hydrogeology

Department

School of Earth & Environmental Sciences

Advisor(s)

Brian Jones

Abstract

AGL Energy Pty Ltd owns and operates the Camden Gas Project in the Southern Sydney Macarthur region and are currently extracting water and methane from the underlying Illawarra Coal Measures. Within the Macarthur region are two groundwater monitoring sites located at Menangle Park and Denham Court. At each site has four monitoring bores established to monitor the groundwater levels and allow water quality testing. These monitoring bores enable the characterisation of the local groundwater system and an assessment of impacts from coal seam gas extraction on the groundwater system. The Menangle Park monitoring bores are within 100 metres of active production bores whereas Denham Court is ~15km outside the current Camden Gas Project. Both Menangle Park and Denham Court monitoring bores record the groundwater levels of the geological units such as alluvium, the Wianamatta Group and the Hawkesbury Sandstone. Groundwater level hydrographs assess and compare the recharge/drawdown characteristics. In addition, water samples were taken from the Menangle Park monitoring bores (MPMB01, MPMB02, MPMB03 and MPMB04), the nearby production bore (MP17) and the Nepean River. The samples were measured for major ions, elements, radioisotopes and stable isotopes. The techniques involved AMS, CRDS, EA-IRMS, IC and ICPMS. The results characterised the Hawkesbury Sandstone at Menangle Park into an ‘upper’ and ‘lower’ level separated hydrogeologically by a 12 metre thick shale layer. The ‘upper’ level was dated at 600BP whereas the ‘lower’ level was dated between 14,500-16,000BP. The hydrogeochemistry of the coal seam water was significantly different to the Hawkesbury Sandstone however, the age calculations were unrepresentative and unreliable. The water quality was assessed in the Hawkesbury Sandstone and was found to be relatively fresh whereas the Bulli Coal Seam was saline. Interpretation of these results suggests no or negligible hydraulic connection between beneficial aquifers and the coal seam aquifer. Based on this the author concluded that there is negligible impact from coal seam gas extraction on the Hawkesbury Sandstone. However, the data available did not enable the author to make an assessment for the likelihood of long term impacts from coal seam gas extraction.

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