Scott Base is located in one of the world’s harshest environments. What are the key challenges for WSP Opus and the wider design and construction team?
In terms of timings and logistics this is a project like no other. It’s a very short construction season with only a four-month window between November and February, when there is enough daylight and it is not so cold. For speed and ease of construction, the new base will be a modular structure in a similar manner to its predecessor, with as much as possible prefabricated and assembled before being shipped to Antarctica from New Zealand. Because of the ice, the sea isn’t navigable until January (late summer), so all the materials for the following year have to be delivered by then so building can start promptly the next summer.
The foundations are the biggest structural challenge because of the permafrost and the way it freezes and thaws, calling for non-standard designs to cope with the different conditions. We’re looking at a range of options, including building on concrete pads anchored to the permafrost, and a method using ground refrigeration that’s used a lot in Canada. Actually excavating the foundations is incredibly difficult, since ice is quite elastic, and therefore very difficult to excavate with a machine. It will have to be done using drill and blast techniques and is very labour-intensive.
There’s also the cold – Antarctica has the coldest climate on the earth! A hot day in summer is -3 OC. When I was there last November it was -5, but that was more like -19 with the windchill. In addition the atmosphere is extremely dry, which affects our choice of materials for the project. In particular shrinkage of timber is a big problem, so any wood used will have to be specially treated.
What are your impressions of Ross Island?
I spent a week there last November getting to know the base, how it works, and what the environment is really like. It’s hard to describe the scale of the landscape. Scott Base is a large complex, but when you land on the ice shelf, it’s just a dot on the landscape on a very small corner of the Ross Ice Shelf.
Scott Base is about 3.5 kms distant from the American base, McMurdo Station. With around 1200 people, they are much bigger than Scott Base, and we will work together with logistic support once construction starts. We had a chance to meet some of the staff there, and get a better understanding of how McMurdo station functioned.
What about climate change, and planning for the future?
We’re looking at a design life of 50 years for this facility and climate change is a serious consideration. For example, we have to take it into account when deciding on the depth and type of foundations in case the active layer of permafrost changes. We’ve considered seismic activity, though historically the risk is very low in this area, but if the ice cap starts to melt, that could affect local tectonic movement. Then there’s Mount Erebus not far from the base, the most active volcano in Antarctica, which is continuously active, but at a low level. Input received from a volcanologist noted it has been stable in the past, but this could change at any time!
Climate change and natural hazards are difficult to predict, and we’re on a constant learning curve. But that’s what makes this project so interesting.