Hopeland and surrounding region testing
Soil vapour testing
In 2015, the department identified the presence of particular gases, such as hydrogen, at unexpected levels in soil depths below two metres underground at a number of locations in the Hopeland region, near Chinchilla. These gases were not detected above undisturbed ground surfaces or in the air.
The department established an excavation caution zone (ECZ) as a result of these findings and provided cautionary advice to the community in relation to the risk that these gases pose during excavation or trenching works below depths of two metres from the surface.
Supplementary soil vapour sampling was undertaken in 2017 and 2018. The department was advised that the findings of the testing showed a decline in hazardous soil gas levels regionally which has significantly reduced the risk to landholders.
In early 2018, the department removed the ECZ and investigation area in the Hopeland region. The department recommends that landholders still consider the cautionary advice during excavations that disturb the soil at depths of greater than two meters in the region.
A number of soil vapour bores are installed throughout the region as part of the investigation. The department continues to monitor soil gas regionally and will remain engaged with landholders regarding the results of this testing and the future of these installations.
Cautionary advice should still be considered
The department’s current advice to landholders in the region is as follows.
There may be a flammability risk that exists during excavations that disturb the soil at depths of greater than two metres. The degree of risk may be increased when activities involve the creation of confined spaces and where potential ignition sources are involved. Anyone engaged in such activities is advised to exercise caution and consider undertaking a site-specific risk assessment prior to carrying out those activities to identify measures to minimise the risk.
Risk minimisation measures to consider include:
- engaging an appropriately qualified person to advise on the potential risks involved in carrying out a given activity and measures that should be put in place to deal with those risks
- avoiding conducting works unaccompanied where such works involve excavation or disturbing the soil at depths greater than two metres
- monitoring gases during works, particularly at the point of disturbance and prior to introducing any potential ignition source or entering a confined space
- ventilating areas of disturbance and confined spaces to disperse and dilute gases
- removing or avoiding ignition sources completely from the immediate vicinity of the disturbance and establish a buffer zone around the works until the absence of unsafe gas concentrations are confirmed
- keeping flammable items and liquids well clear of the excavation/disturbed area
- consider using equipment that is certified flameproof, and
- assessing activities to ensure that the Workplace Health and Safety requirements are complied with.
The advice is cautionary only and not prohibitive.
Contact the department by email on DESInvestigation@des.qld.gov.au for further information.
Regional air quality investigation
Air quality in the Hopeland region was monitored during 2015–16 by the former Department of Science, Information Technology and Innovation (DSITI) through two rounds of extensive air quality sampling and assessment. The monitoring did not find any evidence of subsoil gases leading to unsafe levels of air pollutants in the community. This suggests that any surface emissions of the soil gases that may be occurring are likely to be gradual and quickly diluted by surrounding air to very low levels. Two reports on air testing in the area are available for download:
- Air Quality Investigation Hopeland and Chinchilla March 2015
- Air Quality Investigation Hopeland and Chinchilla December 2015
Surface soils, surface water and groundwater
The department is advised that because the gases are found at depth in the soil, immediate impacts to grazing animals and stock are considered very unlikely. To provide further certainty, the department conducted specific assessments of air, soil, surface water and groundwater on landholder properties within the former ECZ (removed 2018) and investigation area in addition to soil gas sampling.
Testing of surface soils, surface water and groundwater (as collected at the surface) was undertaken on 28 properties in 2015 and 2016 and did not reveal any associated impact. Testing on 20 properties in 2017 and 2018 confirmed this conclusion.
Quarterly groundwater bore sampling
The department conducts groundwater sampling on a quarterly basis at various locations throughout the Hopeland region. The latest round of sampling was completed in October 2019. The department remains in contact with landholders regarding the testing.
Chinchilla’s town water supply
Chinchilla’s town water supply was assessed by Queensland Health when soil gas contamination in the area was first discovered in 2015. Queensland Health advised that the results of testing undertaken on Chinchilla’s town water supply were all within the range of historical data for each water quality parameter, or within the expected range for surface water in Queensland. Queensland Health further advised there was nothing in the water quality data that would indicate a health risk from Chinchilla’s treated drinking water, or that additional testing of the treated water was necessary. Water testing of the Condamine River and Chinchilla Weir during 2015 also identified no associated impact.
For further information contact the department by email on DESInvestigation@des.qld.gov.au or phone the pollution hotline on 1300 130 372.
Advice for landholders
The excavation caution zone and investigation area in the Hopeland region was removed in 2018. Landholders should still however consider precautionary advice during excavations in soil at depths of greater than two metres.