by John Weekes
A CONCRETE pumper says he saw 'black tar' seeping up at a Linc Energy site and raised concerns with the company.
Robert Arnold has told a court he noticed some odd occurrences when he went to the Chinchilla site in late 2007.
Linc, in liquidation, is not in court to defend allegations of causing serious environmental damage.
But five not guilty pleas were entered at Brisbane District Court last week, following claims about Linc's underground coal gasification activity.
On Thursday, Mr Arnold told jurors he noticed several phenomena at the site.
"We saw bubbles coming up ... and a black tar substance. We commented back to Linc about it."
"A few of us went over and had a look ... basically it just looked like a heavy black oil ... it was in the puddles as well, in the same area," Mr Arnold added.
"We couldn't place our equipment close to the well because of these overhead pipes ... it was dripping out of the joints."
Prosecutor Ralph Devlin earlier claimed a "bubbling" event happened on the ground after rainfall at the coal gasification site.
Mr Arnold told jurors that after discussing the oozing substance, concrete trucks turned up and he pumped the concrete into a well.
Mr Arnold said he felt the concrete used that time was "very light" but the on-site supervisor made that decision.
Prosecutors previously told the court concerns were raised at various times with Linc leadership about the quality of cement and geological data used at the site.
The Crown has also claimed Linc used its underground wells in a way that made them fail, and allowed contaminants to escape far way, to places Linc could not remove them.
The trial continues. -NewsRegional