Protecting the environment is a priority for the South West Hub Carbon Capture and Storage (CCS) project. Research into CCS is an environmentally responsible investment, contributing to the potential mitigation of carbon dioxide emissions from fossil fuels into the atmosphere.
The South West Hub strives to protect natural resources through the completion of environmental assessments and meeting environmental regulations. This commitment to environmental responsibility encompasses water, soil and air quality.
It also includes land access arrangements, ensuring activities do not interfere with land owners’ day-to-day operations. Carbon dioxide (CO2) injection has a minimal footprint, consisting mainly of a pump and appropriate monitoring stations.
Shallow Well Drilling
An environmental plan was prepared by KD.1 for the Shallow Well Drilling program which occurred during the summer of 2014/15.
The plan was developed in accordance with the ‘Mining Act 1978’ and the ‘Petroleum and Geothermal Energy Resources Act 1967’ and covered the drilling of Harvey 2, 3 & 4 wells.
These wells were drilled on privately owned grazing land, under agreements with the landholders.
The environmental plan detailed management and mitigation strategies to minimise any environmental impacts during the drilling activities.
3D Seismic Surveying has a minimal environmental impact.
An Environmental Management Plan (EMP) was prepared for the South West Hub 3D Seismic Survey, to minimise environmental impacts through data acquisition.
The South West Hub worked with environmental contracting company Umwelt to ensure the surveying met environmental guidelines. An executive summary of the interim Environmental Management Plan is available.
The survey was conducted on private property and a conservation estate, in areas primarily used for stock grazing. Native remnant vegetation, wetlands and other environmental values were present within the area and are therefore at risk of impacts from the survey.
The purpose of the EMP was to provide a background to the survey activities; detail the proposed survey lines where the activities were to be conducted; and highlight the pre-survey tasks. The EMP discusses the environmental landscape of the Project area and provides details of mitigation measures utilised to ensure environmental impacts were as low as reasonably practicable (ALARP).
This EMP stipulated these controls were in place at all times:
- Work to be completed during dry season to minimise environmental and landuse impacts and disturbances
- No use of bulldozer-sized equipment in vegetation clearing, and rehabilitate or remediate land as soon as possible
- Allow vibroseis trucks site access via existing tracks or previously disturbed areas, keeping entry and exit points to a minimum
- Use roller mulching or mowing methodology or hand pruning clearing methods to preserve rootstock
- Do not disturb wetlands of conservation significance
- Weed and dieback brush down hygiene procedures, to prevent weed and dieback spread
- Fire prevention procedures
- Report any environmental incidents
- Ensure sites remain litter and rubbish-free, with any hydrocarbon spills cleaned up as soon as practicable
- Seek permits and authorisations to access Department of Environment and Conservation (DEC) managed land
- Access in DEC Managed Land for the placement of geophones will be completed on foot.
All selected CCS sites are geological formations that do not contain potable water and therefore could not be used to supply drinking water.
The Lesueur saline aquifer is hypersaline - it is saltier than seawater, which is about 35,000 parts per million (ppm). Drinking water is 450ppm or below.
The water contained within the Lesueur Sandstone is not a potential water source for drinking or industrial use. As the graphic demonstrates, the South West's main freshwater aquifer, the Yarragadee, was eroded from this particular area about 130 million years ago, and can therefore not be contaminated.
No other significant deep potable water sources are present in the Harvey–Waroona area, which eliminates any risk of any CO2 mixing with important freshwater sources. However, the presence of the Leederville Aquifer and sub-surface water supplies close to the surface are acknowledged.
The graphic on the right is a snapshot of the salinity levels of aquifers beneath the Harvey–Waroona area.
Groundwater resources of the Lesueur carbon storage project area (PDF 4mb) (SW Hub) by Phillip Commander.
Harvey 1 well
The Harvey 1 stratigraphic well, located on rural land along Riverdale Road, was operational between February and March in 2012.
This well was drilled on behalf of the South West Hub in order to provide information about the potential for the deep underground storage of CO2.
Data and samples collected during the drilling have been the subject of five intensive research projects conducted by independent research partners.
Harvey 1 has been plugged and the drill site rehabilitated back to grazing land.
CCS surface facilities
A demonstration of geosequestration is underway at Otway in Victoria, where CO2 is being extracted from natural deposits and then re-injected into a reservoir. The project has been deemed environmentally safe and has met government and community expectations.
The injection site consists of CO2 compression equipment and injection pipes, with an office and visitor centre, and several monitoring stations, on a one or two hectare property.
CCS injection sites are carefully selected after extensive testing and sophisticated seismic analysis is carried out on the underground formations or stratigraphy.
An underground reservoir for CO2 storage has to meet strict environmental requirements before it is approved for use.
In Western Australia, legislation is before parliament which would allow for potential underground reservoirs to be licensed for use by the State Government.
Any potential for CO2 to migrate to the surface or into potable aquifers will rule out an area for use as a reservoir, as will the potential for resource conflicts with oil, gas or water.
Any CO2 injected into a reservoir will be monitored to ensure it remains trapped, in much the same way as natural deposits of gas, including CO2, are trapped.
There are four trapping mechanisms that encase CO2 within saline aquifers such as the Lesueur Sandstone. These include structural trapping within pore spaces, as well as mineralisation, dissolving in saline water and the presence of a sealing layer above the reservoir.
Any reservoir will need to meet the requirements of government licensing, including a rigorous assessment to ensure that the nominated storage site has appropriate trapping mechanisms, and is suitable for long-term containment of CO2. Only sites that meet these requirements will be considered for licensing.
In the unlikely occurrence that any CO2 migrates to the surface, a gradual slow release of CO2 would be expected, similar to the everyday release of CO2 into our atmosphere.
During 2012, an environmental survey of the Dampier to Bunbury Pipeline corridor was commissioned on behalf of the Department of Mines and Petroleum. In the future this corridor may be used for a CO2 pipeline to an injection site in the Harvey-Waroona area.