Gas Watch 80 - Danger to ground water in Hunter Valley
Date: 10-Apr-10
Author: Graeme Gibson
AGL Energy - unable to provide proof
Danger to ground water in Hunter Valley
At the insistence of the community of Broke and Bulga, AGL Energy commissioned a water study at one of two wells drilled in 2004 adjacent to the village of Broke, in an attempt to ensure that there is no danger to the upper fresh water aquifers through which AGL is drilling for coal seam methane gas.
This well was drilled some 300 metres down into the coal seam, through the upper fresh water aquifers relied upon by the village and farming communities.
AGL is claiming that there is no connectivity between the coal seam and the fresh groundwater and therefore no risk to the groundwater.
The peer reviewer of the AGL study, Professor Garry Willgoose of Newcastle University, says that he is satisfied that the strong indications are that there is no danger to the fresh water aquifer at that well, and for a very small area around the well.
Professor Willgoose is, however, unable to give any guarantee. He opines in his report : This result is consistent with there being no leakage from an adjacent aquifer. However, it does not guarantee no leakage."
The Professor further says: "Accordingly, the peer reviewer cannot provide a reliable estimate of the region of impact of the pump test within the aquifer. However, all of the results in the modelling suggest that it lies at the lower end of the range suggested by PB and probably in the range 20-50 m out from the well." "The pump test does not provide any direct information on the leakiness outside of that cone of depression." ie the 20 to 50 metre radius.
So, whilst the community tried to take some comfort from the strong indications of no connectivity, the community was faced with no guarantees, no proof, and a test area of only about 60 metres in diameter, which cannot be extrapolated out to the broader methane gas exploration area.
So, now a flow test for 6 months from the same well extracting some 30,000 litres of toxic water per day to see if there can be any proof that there is no risk of losing or contaminating the fresh water aquifer. Fortunately this will also be monitored closely by Professor Willgoose, as the area of affectation will be more than 30 metres, it will be some 300 metres and will go under the vineyard village of Broke.
PO Box 120 Broke NSW 2330
www.huntervalleyprotectionalliance.com
April, 2010.
Contact: Graeme Gibson 02 65791062
