Under the proposal, QGC would have supplied 3000 to 5000 megalitres a year of water produced at its Berwyndale South CBM project near Chinchilla to Toowoomba City Council.
But the Department of Natural Resources and Mines estimated the cost of building a desalination plant, pump stations and a 180km pipeline to supply the treated water to Toowoomba each year at $A150 million.
The report also found that the quality and quantity of water available would vary with the location and during the life of each well drilled in the project.
Townsville Council also raised concerns over the presence of polyaromatic hydrocarbons – potent carcinogens and radio nuclides often associated with coal – that could potentially require a more stringent pre-treatment process.
The long-term reliability of the proposal was also considered questionable, with the source having a total life as short as 15 to 20 years.
The department concluded that the proposal was not viable from either an economic or an environmental perspective.
The report ultimately concluded that making use of water produced by CBM operations "probably has better application where smaller quantities are involved and the end use is located closer to the place of production."
Not far from Toowoomba and Chinchilla, Dalby Town Council and Arrow Energy are testing and assessing the treatment of CBM water to potable standard. They have an application for funding assistance before the National Water Commission.
