Queensland's environment department has lifted a warning zone from a contaminated site on the Darling Downs linked to former underground coal gasification project.
After conducting nearly 2000 soil gas tests since 2015, the department said the most recent results showed an overall reduction in soil gas contaminant levels in the Hopeland region.
However, landholders excavating soil more than two metres deep are being encouraged to continue risk-minimisation practises.
Restrictions were put in place in February 2015 after Linc Energy’s UCG plant in the area was allegedly found to have caused widespread contamination of the surrounding farmland.
High concentrations of hydrogen, as well as methane and cancer-causing benzenes were found in the soil.
In February last year testing revealed the contamination was more widespread than first thought, extending beyond the initial 314 square kilometre “excavation caution zone”.
The zone was put in place primarily because of concerns the flammable hydrogen could combust if disturbed by digging equipment .
The department will continue to sample soil vapour bores and groundwater over the next year to ensure there is no upswing of gas levels.
Testing has not found any contamination of local drinking water supplies, air quality or agricultural products, and the department says human health is not impacted.