This season, the Remediation Team at Casey research station is focused on the clean up of four fuel spill sites at various stages of investigation, remediation and research. In December, we began a detailed investigation of the 2018 fuel spill at the Casey upper fuel farm. This included drilling through ice, down to bedrock in a grid that spans the area down gradient of the fuel spill. Vapour cartridges were installed, that once analysed, will give an indication of the extent of fuel migration below the ice. We encountered areas of snow and ice pack deeper than 4m and could only install pipework to this depth. Results from this investigation will inform us which areas to prioritize for future remediation activities, for example, how much ice will need to be dug out to access the impacted soil?
Work has also continued on the 1999 fuel spill site where contaminated soils were undergoing treatment in the first generation of biopiles, originally built in 2011. Biopiles allow the natural bacteria in the soils to break down the fuels and use fuel as food. They are contained in bunded areas so that fertilizer and water can be recirculated through the soils. These soils have now been stockpiled for either reuse on station in approved environmentally managed applications or for further bioremediation treatment.
In the past few weeks, we took apart two biopiles and completed a detailed investigation of the geosynthetic barrier system that contains the contaminated soils and leachate (water). The design, construction and performance of barrier systems has been ongoing since 2010 with external university collaborators. We have completed drone flights to capture detailed photographs and maps of the barriers and foundation soils. With the doctors at Casey, we completed X-rays of the liners that show the presence or absence of water in the synthetic clay liner with void spaces being potential contaminant pathways.
One biopile was built on a relatively dry and coarse gravel foundation and another was built on a finer soil foundation that experiences a seasonal pulse of melt water running just below the barrier system. The learnings from these barrier designs, decommissioning studies and laboratory testing has helped us with the design of a new biopile to be constructed in January 2020. This will be the largest biopile built at Casey and will allow the small excavator to drive inside and turn soils (especially frozen soils) for enhancing bioremediation.
Before the new biopile is built, our team must complete excavation of the remaining contaminated soils in the ground from the 2015 fuel spill. From our team’s collective soil remediation research and logistical experience, we know that the best method of containing and cleaning up fuel impacted soils is to get the soil out of the ground, into a biopile and encourage the natural bacteria to begin degrading the fuel. We have already successfully remediated two other areas impacted by this fuel spill: the area below the new Casey Utility Building and the sloped area that was the source zone of the fuel spill.
Our team is also completing work on soil biodiversity, ecological risk assessments, microbiology, ecosystem research and developing a framework for the Australian Antarctic Division (AAD) and other nations to guide soil reuse policy. The field team on the ground at Casey were able begin some of the soil sampling, mapping and investigative work at field sites a short distance from station.
It is important to note that less than 1% of the Antarctic continent is ice-free and soils are exposed. Essentially our greater team is aiming to answer the following questions:
How are soils, water, plants and animals (e.g. tiny invertebrates) impacted by humans in Antarctica?
What types of remediation are possible and practical in Antarctica and other cold regions?
- When is the soil clean enough to be returned to the natural environment?
This work involves many collaborators, AAD team members, trades workers, and Australian and international universities. We are a big project!
The AAD Remediation Team is very outdoorsy, enjoys long walks, an adventure, taking in the stunning views here at Casey, and spending time with each other. Pulling sleds and donning survival packs is a nice change of pace to our usual workday on station using heavy machinery, drones, shovels, pumps and Stanley knives.
-AAD Remediation Team