Hopeland and surrounding region testing
The Department of Environment and Heritage Protection is continuing to test and monitor soil gas contaminants in the Hopeland and surrounding region as part of an extensive ongoing investigation.
Phase one testing
In February 2015, EHP 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.
EHP established an excavation caution zone 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.
EHP has been advised that the gases detected are not associated with coal seam gas development.
Phase two testing
More recently EHP 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.
EHP’s second phase of testing has revealed hydrogen contamination at potentially hazardous levels outside the boundary of the existing excavation caution zone.
EHP will continue to test to understand the extent.
Hydrogen present below two metres underground in the soil profile may present a flammability risk during excavations that disturb the soil at depth. The degree of risk is increased when confined spaces and known ignition sources are involved.
Persons engaged in such activities should exercise caution and consider undertaking site specific risk assessments to identify measures to minimise the risk. Risk assessments should be performed prior to undertaking works that have the potential to intercept the soil gases. Risk minimisation measures to consider include as follows:
- Avoid conducting works unaccompanied that involve excavation or disturbing the soil at depths greater than two metres;
- Monitor gases during works, particularly at the point of disturbance and prior to introducing an ignition source or entering a confined space;
- Ventilate areas of disturbance and confined spaces to disperse and dilute gases;
- Remove or avoid ignition sources completely from the immediate vicinity of the disturbance – i.e. establish a buffer zone around the works;
- Keep other flammable items and liquids well clear of the excavation / disturbed area;
- Consider the use of equipment that is certified flameproof; and
- Refer to the Workplace Health and Safety Queensland Guidelines for works involving a confined space.
The advice is cautionary only and not prohibitive.
Anyone seeking advice or who has further queries can contact EHP via email at email@example.com.
Where does the cautionary advice apply?
The present excavation caution zone remains in place. The areas shaded on the map are areas presently under investigation by EHP and its advisors. The cautionary advice described applies to the excavation caution zone and the investigation area and surrounds. EHP is still testing to understand extent. For that reason, site-specific risk assessments near both these areas should be undertaken to confirm that any proposed works that may disturb the soil below two metres depth can be safely carried out.
EHP will continue to provide updates about the areas under active investigation. You will see EHP officers out and about in this area. If in doubt, email firstname.lastname@example.org or contact EHP’s pollution hotline on 1300 130 372.
Regional Air Quality Investigation
Air quality in the Hopeland region has been monitored by the 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
EHP 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, EHP and its independent experts commenced specific assessments of air, soil, surface water and groundwater on landholder properties within the soil gas contamination area in addition to the ongoing soil gas sampling being undertaken.
Testing of surface soils, surface and groundwater on 18 properties have not revealed any associated impact.
Farm Health Assessments
Given the results of the second phase of testing, EHP and DSITI will continue testing surface soil and water as part of a farm health assessment program.
Anyone within the ECZ and surrounding areas who would like testing conducted on their property can contact EHP via email at email@example.com.
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.
Queensland’s Chief Health Officer has been briefed, and has advised that EHP’s “measures to advise landholders and businesses in the vicinity of the risks are prudent and responsible”.
EHP will continue to update the community with the latest developments.
Anyone seeking further information is invited to email firstname.lastname@example.org or contact EHP’s pollution hotline on 1300 130 372.