L&M Energy may have to build a desalination plant to treat contaminated water from gas wells in Western Southland.
The coal-seam gas operations around Ohai have the potential to produce large amounts of waste water, which company managing director Kent Anson said would need to be disposed of.
Water from the pilot well is discharged untreated into the Orauea Stream, near Bluebottle Rd south of Ohai, as per its resource consent approved by Environment Southland.
Commercial operations could see significantly more waste water produced from additional wells in the Waiau Basin area.
Water released from coal seams has a high saline and sodium content, but can be treated and turned into useful fresh water. “What we’d like to do is turn it into a usable resource with a small desalination plant,” he said. “Then it could be used for irrigation or livestock.”
If commercial production was to go ahead, the desalination plant would be built at a central location with the gas compressor station.
The Western Southland gasfield will not produce as much waste water as Australian coal seam gas operations, Mr Anson said, because of the less porous nature of the rock.
“The end game is selling gas,” Mr Anson said. “All water and gas collected from the wells will be gathered to a central point.”
Under the existing test site resource consent, the company is allowed to discharge up to 1.75 million liters of water a day into the Orauea Stream. The water is monitored and tested to ensure the stream is not affected.
Environment Southland consents officer Stephen West said if the company was to open new wells, it would need to amend its existing test site consent to include discharge from other sources. The test site’s present discharge was trivial, he said.
In Australia, where coal seam gas has become a huge growth industry, wells can produce between 5000 and 20,000 litres of waste water a day. The water has been stored in large evaporation ponds.
There have been concerns water could leak out of the ponds and poison the surrounding land.
As a result, the Queensland State Government introduced stringent regulations for coal seam gas water in 2008. Evaporation ponds are to be phased out.
In response, companies such as Queensland Gas have spent millions of dollars on treatment plants and pipelines for the waste water. The Queensland Gas plant, near Chinchilla, cost more than A$350 million (NZ$439m).
The start of production from L&M’s pilot well was held up last month because of technical problems with the flow of water and gas.
