One of the most significant unresolved questions as coal seam gas wells expand rapidly across eastern Australia is how the industry will deal with the huge volumes of salt it produces.
CSG production involves removing water from coal seams to free-up trapped gases. The water typically contains high quantities of salt which has to be managed in an environmentally acceptable way once brought to the surface.
Community groups have long been concerned that CSG companies are being granted environmental approvals to proceed by Governments eager to generate royalty flows and new jobs before they have solid plans in place to deal with the contaminated water and salt their developments will produce.
After studying the Environmental Impact Statement of Arrow Energy’s Surat Gas Project in Southern Queensland, Darling Downs landholder and rural community group Save Our Darling Downs says it is clear the company has “no idea” about how to handle the vast tonnages of salt it will generate.
Arrow Energy has rejected the criticism, stating that it is committed to removing all produced salt from the local landscape, and that it is considering several options to to deal with the problem.
Save our Darling Downs says figures contained in Arrow Energy’s EIS show that the company plans to pump around 770 gigalitres of water from the region’s coal seams – one and half times the volume of Sydney Harbour – which will contain 3.5 million tonnes of salt.
The group says the options being considered by Arrow, which include ‘disposal to watercourses’ and ‘ocean outfall’ (pumping the water to the ocean), would have serious environmental implications.
The use of reverse osmosis to allow “beneficial re-use” of water is also cited, but the group points out that this is not a workable solution to handle the massive volumes of water involved.
The groups says the estimates contained in Arrow’s EIS suggest that if all water produced over the life of the project was treated, the process would produce around 117–175 million tonnes of brine.
In terms of how the brine would be treated, the EIS states that it would be stored in dams and disposed to a suitably licensed landfill. The closest suitable waste disposal facility currently available is located at Swanbank, near Ipswich, around 150km from the project area. The EIS states: “This EIS has assumed that all brine concentrate will be trucked to Swanbank.”
By Save our Darling Downs’s calculations, the best case scenario of 117 million tonnes of produced brine would equate to 2.9 million B-Double truck loads (at 40 tonnes each) travelling through Toowoomba and down the Warrego Highway to Swanbank.
Group spokesperson Ruth Armstrong said Arrow Energy’s Surat Gas Project, if approved, would effectively be mining groundwater from the Great Artesian Basin and Murray Darling Basin.
“By the industry’s and the state government’s own admissions, this water mining is not sustainable,” Mrs Armstrong said.
“Arrow Energy’s plan for disposal of the salt produced by its Surat Gas Project is plainly ridiculous and impractical.
“The truth is, Arrow has no idea what to do with the salt, and the likely outcome would be storage in dams across the Darling Downs. This would be a ticking environmental time-bomb, posing a great risk to the Murray-Darling Basin’.
In a written statement to Beef Central, Arrow Energy said the group’s calculations were incorrect and exaggerated the volume of bring that would be produced.
“Arrow understands the importance of water for all communities and is committed to removing all produced salt from the local landscape,” the company's response said.
“Our preference is to identify a beneficial use for the salt produced from our operations.
“Arrow is considering several options for managing salt including our preferred option of processing for beneficial use, injection into an aquifer, pipeline to the ocean or disposal to regulated landfill.
“Any disposal at regulated landfills, for example a facility similar to Swanbank, would involve regulated transport of dry salt after water treatment not salty water. Arrow would use landfills that meet all strict environmental conditions and regulations.
“In the Surat Basin, Arrow and two other major CSG companies are also evaluating the potential for a combined salt recovery plant that could create marketable salt products.
“The brine estimate of 117-175 million tonnes is incorrect. This amount is likely to be much less, up to 3.5 million tonnes of salt over 30 years.
“The brine is reduced to dry salt due through natural evaporation or enhanced crystallisation processes.
“Arrow is encouraged by the recent Queensland Water Commission Underground Water Impact Report that found minimal impacts from coal seam gas activity on groundwater levels in the Condamine Alluvium, particularly around Cecil Plains.
“The findings in the report support those provided in Arrow's Environmental Impact Statement for the Surat Gas Project.”