Serious environmental harm was caused by failed Queensland company Linc Energy's underground coal gasification operations on the Darling Downs.

The company was on Monday found guilty of five charges of wilfully and unlawfully causing environmental harm after toxic gas leaked from four of its Chinchilla sites between 2007 and 2013.

Scientists and workers warned senior managers about gases bubbling from the ground but the company kept operating, with the prosecutors arguing profits were put ahead of the need to follow environmental guidelines.

The ground had been fractured by Linc injecting air as part of the UCG process and while the company tried to seal them with concrete and use wells to control pressure this didn’t sufficiently reduce risks or damage.

During trial the Brisbane District Court heard the UCG operations left water polluted to the point it was unfit for stock to consume.

Sentencing has been scheduled for May.

* Between 2007 and 2013 toxic gas leaked into ground water from Linc’s four underground coal gasification (UCG) sites in Chinchilla

* April 2016 – Linc goes into voluntary administration, owing $289m to creditors

* May 2016 – Queensland government environmental protection order seeks $5.5m from Linc to rehabilitate sites

* October 2016 – Court of Appeal dismisses Linc chair Peter Bond’s attempt to overturn EPO

* November 2016 – Liquidators challenge EPO, claiming liquidated companies need not comply

* March 2018 – Supreme Court rules in liquidators’ favour over EPO

* April 2018 – Linc found guilty of five charges of wilfully and unlawfully causing serious environmental harm following week’s long Brisbane District Court trial

* May 2018 – Sentence expected over April convictions

* Mid-2018 – Five former Linc Energy executives, including Bond to face committal hearing in Brisbane Magistrates Court for alleged environmental breaches