Going "underground"
Jan Erik Kaarø
In the County of Romerike, the biggest soil investigations in Norwegian history is nearly finished.
Atle Dagestad, a graduate student at NTH's Dept. of Geology and Mineral Resources Engineering (left), Geir Westerlund, Division Director at SINTEF Geotechnical Engineering, and Senior Research Engineer Sveinung Sægrov of SINTEF NHL are all involved in Gardermoen projects.
A number of engineering consultants are currently involved in a hectic phase of the planning process for the new main airport at Gardermoen.
Both SINTEF and NTH landed long ago at the new airport. SINTEF Geotechnical Engineering has been a scientific consultant since 1990. Among other things, SINTEF's geotechnicians have been responsible for deciding the scope and content of investigations of soil conditions, and they are now involved in studies of the groundwater situation under different construction and operating conditions.
NTH and SINTEF are also participating in The Gardermoen project which is part of the the "Environment of the subsurface" research programme. The Norwegian Agricultural University and the University of Oslo are also involved in the project, which is due to come to an end next year. The primary sponsor of the project is the Civil Aviation Administration.
Will be affected
The estimated cost of the new airport is about NOK 20 billion, and it will cover an area of about 13 square kilometres. In comparison, the widely discussed groundwater reservoir is about 100 square kilometres in extent. Norway's biggest groundwater basin lies for the most part in sand and gravel. The water surface is between three and 20 metres below ground level and the main reservoir varies from 10 to 50 metres in depth. Some scientists believe that a further reservoir lies even further down, below a thick layer of clay.Geir J. Westerlund, Division director at SINTEF Geotechnical Engineering, admits that the basin is bound to be physically affected by the construction of the airport. For example, the railway tunnel to the terminal will be so deep that it will act as a sort of groundwater separator through the whole area. SINTEF Geotechnical Engineering has suggested to the Civil Aviation Administration how the 1300 m long culvert can be kept dry and how the tunnel can affect its surroundings.
De-icing aircraft during the winter months is another threat, which is currently being studied in detail by researchers at the Agricultural University of Norway. "We can never manage to protect groundwater 100%. But any contamination caused by airport operations should be regarded with respect to current water quality. No-one knows exactly just how pure it really is. We can assume that emissions from an aircraft cemetery and from the Air Force's activities at Gardermoen have left traces," points Westerlund out .
The groundwater contamination studies also involve NTH's Department of Geotechnical Engineering and Department of Geology and Mineral Resources Engineering. For the time being, Gardermoen projects are absorbing some 20% of the scientific capacity of SINTEF Geotechnical Engineering.