Hopeland and surrounding region testing
Latest update: November 2018
In October 2018, the department concluded a fourth phase of soil vapour sampling. The sampling involved the collection of soil gas from permanent soil vapour bores installed through the Hopeland region.
The results of this sampling are consistent with the phase three sampling and shows a significant reduction in the risks to landholders from gases such as hydrogen in the Hopeland region.
The information below provides background to the testing undertaken in the Hopeland and surrounding region. The department recommends that landholders still follow the precautionary measures detailed below when undertaking excavations that disturb the soil at depths of greater than two metres (on this page).
Phase one testing
In February 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. 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.
The department has been advised that the gases detected are not associated with coal seam gas development.
Phase two testing
The department then conducted a second phase of soil gas testing in Hopeland and surrounding localities. The aim of the second phase was to better characterise the behaviour of the contaminant gases over time. This testing program involved drilling approximately 70 additional bore holes to test soil gas vapours within the soil profile and re-testing long-term soil vapour monitoring bores installed in 2015.
The department's second phase of testing revealed hydrogen contamination at potentially hazardous levels outside the boundary of the existing excavation caution zone. Expert analysis and advice from that testing resulted in the department imposing an investigation area to the south of the ECZ.
Phase three testing
A third phase of testing was conducted in 2017. The testing involved the collection of soil gas from auger holes together with gas contaminants from permanent vapour wells. The methods used were intended to replicate what a landholder might encounter in augering a hole, together with the ability to see whether the gases were increasing or decreasing over time at locations where high gas levels had been detected.
The department was advised that the results of the third phase of testing showed a significant reduction in concentrations of both methane and hydrogen in the near surface environment. The department received advice that, the results of the third phase of testing tend to show a lessening in the severity of the risk to the landholders within the ECZ and investigation area.
Removal of the mapped ECZ and investigation area
The findings of phase three testing (and confirmed by phase four testing) show a decline in hazardous soil gas levels regionally which has lessened the severity of 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.
Community members should be aware, that the ECZ and investigation area was informed by an assessment of the geology and the geomorphology in this area in conjunction with results obtained during investigations. This meant that neither the ECZ nor investigation area could be treated as a detailed map that defines exactly where gases are, or are not, in the landform.
The previously mapped areas simply provided a mechanism to advise the community the areas of heightened risk based upon multiple lines of investigation and reflected the most current information at the date of implementation.
While regional results point to a decreasing risk to landholders as it is not possible to perform a detailed mapping exercise and the fact that various pathways exist in the landform for gases to travel, landholders are encouraged to conduct site-specific risk assessments and still consider the department’s cautionary advice.
The department’s current advice to landholders in the region is therefore 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.
Anyone seeking advice or who has further queries can contact the department via email at firstname.lastname@example.org.
Regional Air Quality Investigation
Air quality in the Hopeland region has been monitored 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. DSITI’s 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 and investigation area in addition to soil gas sampling.
Testing of surface soils, surface and groundwater on 28 properties through 2015 and 2016 have not revealed any associated impact. Testing on 20 properties in 2017 and 2018 has confirmed this conclusion.
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. 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.
Anyone seeking further information is invited to email email@example.com or contact the department's 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.