This week at Casey: 23 December 2016
Casey Station is kept busy with yearly resupply but remediation work goes on.
Our ship comes in
After several weeks of anticipation and more weeks of meticulous planning, the Aurora Australis pulled into Newcomb Bay this week to commence the 2016/2017 Casey resupply.
The ship created a spectacular photo opportunity as it dropped anchor and commenced to unload cargo, before starting on the station refuel. Normal station operations have been suspended whilst everyone lends a hand, whether it be operating the many items of equipment that make unloading and reloading happen or just manual labour unloading the dozens of containers that come onto station. Even our director Nick, who is currently visiting Casey, lent a hand to fill the freezers and food store.
With the hard work comes the excitement of finally getting your hands on your personal cargo, that expeditioners have had sent down to make their season more comfortable. The long hours and effort by all on station certainly increases the level of camaraderie as we all work together to get the job done.
Despite resupply, the remediation team has been hard at work managing groundwater as it flows through our contaminated sites here at Casey.
Our water treatment container (WTC) underwent a retrofit in November (with the help of many Casey tradies). We celebrated the grand opening and promptly began treating surface water, groundwater and bio pile leachate.
The redesign includes larger columns packed with granulated activated carbon, better flocculation, warmer temperatures for the natural hydrocarbon degrading bacteria and a heated hose that reduced daily manual labour in this freeze/thaw environment, thank you Canada for your northern hemisphere tricks! The WTC can treat just over 11,000 litres of water a day when we run it for 12 hours, which we have been able to do now that everything is melting!
In addition to water management, our team completed the build of a brand new bio pile barrier system (named bio pile 8) and we are slowly filling it with soil. Luckily it is warm out and the soil has exposure to heat and oxygen, increasing the microbial degradation of the fuel in the soil.
After designing, constructing and spending significant effort investigating the performance of the barrier system, our team has pretty much got the build phase down pat. This time, we went for the largest bio pile we have ever built, while just almost working within the capacity of our five ton excavator to reach and aerate the soil a few times each season.
The barrier system requires the best sub-grade that Antarctica can offer, and for Casey the gap graded (fines and larger cobbles) and low moisture content soil is always a challenge. To assist the barrier system, we placed a sacrificial retention layer of fine soil that will hopefully be held within the bio pile foundation and not mobilised with the annual pulse of the summer melt.
The next layers included four panels of geosynthetic clay liners and two panels of high density polyethylene plastic welded together by our tradie Colin Ford. Then the protection layers for the main liners were placed and this included screened soil and textiles.
A bio pile barrier system is designed just like a landfill barrier system to hold in leachate (contaminated water) and soil. The challenges of designing in Antarctica come from cold temperatures, freeze/thaw cycles, the arid climate and exposure to high winds and solar radiation. However, despite the challenges the bio piles have been working and last year, after five years of treatment, soil in some of the bio piles was returned to the station as a building foundation material.
It was the first time Australia re-mediated contaminated soil and reused it on site. It was worthy of a celebration after years of working towards proving bio-remediation is possible in Antarctica.