Coastal roads and harbors are traditionally protected from sea erosion by giant blocks of rock or geosynthetic bags filled with material, all locally sourced where possible. In the Arctic and other cold northern regions, where good quality material is often scarce, the prohibitive economic and environmental cost of importing suitable matter has led to a demand for solutions that make use of whatever low quality soil or other material is available.
Geosynthetic bags, which are typically woven textile, polymer-based envelopes, have been successfully used for more than 40 years in temperate climates, but have not been tested in sub-zero conditions.
EUREKA project E! 3702 GISSAC was initiated by TenCate Geosynthetics France, a world-leader in the design and production of geosynthetic materials for civil engineering projects. The company wanted to find out if geosynthetic bags worked in very cold conditions, and to come up with a product that was both environmentally-friendly and sustainable.
"Our northern European sales offices asked us to develop suitable materials for cold regions where the temperature is rarely above zero," explains Dr Olivier Artières, TenCate's Innovation Project Manager and Senior Expert. "They face specific problems such as the thawing and freezing cycles of water that make the construction of infrastructures like roads and jetties difficult.
"Following a discussion with colleagues at Norway's SINTEF Research Institute we decided to hold a brainstorming session with local users to gain a better understanding of their needs and the kind of solution they were looking for. They told us that constructing embankments under water to create dykes and breakwaters was a major problem, and protecting against coastal erosion. This was particularly so in areas such as Svalbard, where traditional solutions are too expensive or don't comply with strict environmental regulations, and which also lack suitable geological material for building protective infrastructures."
The GISSAC project team, with the support of EUREKA and the Norwegian-French Foundation, set about developing envelopes made with textiles comprising different structures (woven, non-woven and knitted) and different types of polymers. Laboratory tests and analysis of on-site results were conducted by French partner CETE Est LRPC Nancy and Norwegian subcontractor UNIS, with PhD and MSc students taking part in the fieldwork.
The project also entailed establishing the optimum shape and size of the geosynthetic bags, or Geobags, and the best method of installation. "The cold makes it extremely difficult to work in the Arctic," explains Dr Artières, "so it was a matter of finding the best compromise between a solution that works well and is also easy to install, as well as being inexpensive and environmentally friendly."
Geobags made from different types of textile were installed along a 100 metre stretch of coastline near a mining camp on Svalbard operated by project partner Store Norske Spitsbergen Grubekompani (SNSG). Over three winters, their response was monitored to the cold, ice movement, currents, abrasion and other stresses characteristic of the area. The results were so good that SNSG used the Geobags to repair a damaged quay wall in the local harbour instead of locally available rocks.
The inexpensive, sustainable solution will be launched on the market in early 2010. With climate change models predicting that the north-western coasts of Canada and Alaska will be ice-free by 2020, and an estimated 25% of the world's undiscovered oil and gas resources located in the Arctic, the market potential for Geobags is considerable, as all new operations will require land-based infrastructures in need of protection. Several new Russian fields are also currently planned in the Barents and Pechora seas.
Given the ecologically fragile nature of arctic regions, Geobags have another significant advantage, says Dr Artières. "Geobag infrastructures are reversible – if they are no longer required, they can simply be emptied and the place left exactly as it was before construction."
The condition of Geobags when they are in situ is relatively easy to monitor, as being positioned on the ground surface of a site they can be checked regularly and replaced if necessary. However, the geosynthetic products used in more temperate climates for dams and flood-protection dikes and embankments are installed invisibly under soil, making it impossible to tell how well they are functioning.
TenCate has recently completed another EUREKA project, E! 3361 SAFEDIKE, which has developed a new, intelligent generation of geosynthetic textiles incorporating sensors and fibre optic technology that enable their condition to be monitored remotely.
"The GeoDetect® system not only monitors a product remotely but also acts as an early warning system, explains Dr Artières. "If the geosynthetic textile's performance starts deteriorating or there's some other malfunction, the system can identify the source of the trouble. The site managers can make a repair before any major damage occurs, especially something potentially catastrophic like a dike or dam failure."