RISKS to groundwater triggered the closure of a Linc Energy generator, as an expert warned the company had no real idea about contamination it had caused.
Former Linc employee Dr Gary Love sent company bosses an email in April 2009 about issues at an underground coal gasification site.
Issues including "risks to groundwater” made it essential to decommission UCG Generator 3, Dr Love said in an email shown to Brisbane District Court.
"There remains great uncertainty as to how the groundwater will respond to depressurization and to the extent of groundwater contamination outside of the generator area.” Dr Love added.
Dr Love, who has multiple degrees in geology and groundwater management, proposed a four-stage decommissioning.
First, he advised for "slow depressurisation”.
Then he suggested low pressure would operate for up to three months, or till chemical analysis of groundwater showed "suitably clean conditions”.
Stage three involved no injection, with periodic flaring for up to six months.
Dr Love told the jury on Thursday a cavity 30m long and 20m wide at the site was "quite developed” and "structural failure” could have happened if pressure was reduced too rapidly.
"We had seen contaminated water outside of the generator area.”
Stage four involved monitoring during and following the end of gasification.
Prosecutor Ralph Devlin asked Dr Love how Linc managers responded to his advice.
Dr Love said he was subject to a "fairly robust” but "healthy level of challenge” because the advice could impact the company's finances.
Earlier in the trial, concrete pumper Robert Arnold said he saw "black tar” seeping up at a the Chinchilla site and raised concerns with the company.
Linc, in liquidation, is not in court to defend allegations of causing serious environmental damage.
But five not guilty pleas were entered on January 29.
The alleged offences happened between July 1, 2007 and December 1, 2013, in Chinchilla.
The trial continues. -NewsRegional
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