Five former executives will stand trial over a failed coal gasification plant.

Linc Energy founder Peter Bond and four other former executives face charges relating to contamination at the company's underground coal gasification (UCG) site near Chinchilla between 2007 and 2013.

The five - Mr Bond, Donald Schofield, Stephen Dumble, Jacobus Terblanche and Daryl Rattai - have all been granted bail.

They are accused of failing to ensure Linc Energy complied with the Environmental Protection Act.

The allegations relate to the escape of toxic gases and subsequent contamination of air, soil and water.

Reports say remediation of the site is expected to take decades.

Linc Energy has been in liquidation since 2016, leaving the site to be managed by the Queensland Government.

Queensland’s Department of Environment and Science (DES) says the investigation was “the largest and most complex ever conducted” by DES.

“The company is alleged to have wilfully and unlawfully caused serious environmental harm as a result of the operation of its UCG facility,” the spokesman said.

“DES, as Queensland's environmental regulator, is committed to pursuing executive officers who fail to ensure companies comply with Queensland's environmental laws.”