Water and Salt
Coal seams contain both water and gas. During coal seam gas operations a large amount of water must be pumped out of the coal seam to lower the pressure and allow the gas to flow to the surface.
At a Sydney meeting in August 2011, Ross Dunn from the Australian Petroleum Production and Exploration Association (APPEA) said that CSG activity “will to varying degrees impact on adjoining aquifers … the extent of impact and whether the impact can be managed is the question.”
The National Water Commission has said coal seam gas development represents “a substantial risk to sustainable water management”. It said that “extracting large volumes of low-quality water will impact on connected surface and groundwater systems” and noted risk factors associated with hydraulic fracturing and reinjection of treated water into other aquifers.
The water extracted during coal seam gas operations is often referred to as “produced water”. This water is generally salty and can contain toxic and radioactive compounds and heavy metals.
Estimates of the total amount of water the coal seam gas industry will extract over the life of the industry vary widely. The amount of water involved in coal seam gas operations also varies, from project to project. The CSIRO says that the amount of water produced during coal seam gas operations can vary from a few thousand to hundreds of thousands of litres a day, depending on the underground water pressures and geology. In 2011, almost 16,000,000,000 litres of water was produced from 3,261 coal seam gas wells in Queensland. In NSW, 249 coal seam gas wells produced 218,000,000 litres.
The extraction of produced water will affect water levels in some adjoining aquifers, in some cases for many decades. Hydrological modelling conducted for Arrow Energy predicting “drawdown in the intermediate and deep groundwater systems to be greater than thresholds set by the Queensland Government”. This means that farmers and other water users reliant on the adjoining aquifers will be affected.
There have been several recent incidents of contamination and pollution related to coal seam gas operations. One coal seam gas company operating in a state forest in north-west NSW admitted that 10,000L of untreated coal seam gas water had been spilled in June 2011. Testing, conducted six months later, of samples taken from near the site of the spill revealed how toxic coal seam gas water can be. The water tests detected heavy metals up to 37 times higher than natural levels and five times drinking water standards. Two coal seam gas operators werepenalised by the NSW Environmental Protection Authority for charges relating to the discharge of polluted water from coal seam gas sites. Meanwhile, in Western Sydney a coal seam gas well blow-out which sent an uncontrolled burst of foam into the air a short distance from an open drinking water channel had operator AGL put on notice by the NSW EPA.
The issue of water contamination from coal seam gas has also been raised in Queensland where locals reported gas bubbling along a 5 kilometre stretch of the Condamine River near coal seam gas operations. Dr Gavin Mudd from Monash University said that it is plausible that coal seam gas is a factor in the methane gas bubbling to the surface of the river.
Salt is another by-product of coal seam gas operations and can have a number of adverse impacts if it enters the surrounding environment. This is a particularly pertinent issue in agricultural areas where salt can permanently damage high quality soils and take them out of production. It is estimated that tens of millions of tonnes of salt will be produced as a waste product of coal seam gas operations over a 30-year period. At this stage coal seam gas companies do not know how they will dispose of this salt. Watch this Lateline Report for more information on the issue of salt disposal.