Approximately six kilometers of the West Link will be built through rock and clay below the groundwater table. Rock, soil and groundwater conditions must be inspected in order to handle risks and to prevent damage.
Along the entire length of the West Link, there is a risk that we will affect the groundwater. Changes to groundwater can affect ancient remains, natural environments and buildings with sensitive foundations. Energy plants and geothermal wells are also sensitive to these changes. For example, lowering the groundwater level can result in less energy being obtained from geothermal plants.
The Swedish Transport Administration will define the groundwater levels at which the various sensitive objects risk being affected and the measures that may be required in such a case. Inspections of buildings that are dependent on groundwater are carried out by measuring groundwater levels in soil and settlement movements, for example. If we detect a deviation, one initial action may be to measure the groundwater levels more often. The next step may involve infiltration to maintain the water level or further water tightening, known as injection. The rock is made watertight by spraying a mixture of water and cement into its cracks.
We began to measure and monitor changes in 2012
The project began to set up measuring tubes in 2012 in order to measure and monitor changes in the groundwater level. We call these tubes measuring points and we have set up 375 of them in Gothenburg so far. Another 250 will be set up during 2016 and 2017. The aim of these measurements is to be able to act as quickly as possible if the groundwater level falls more than normal and there is a risk of damage. We currently carry out monthly measurements. During construction measurements will be carried out at shorter intervals.
The inspection programmes
- Ground water, e.g. ground water level, water leaching into excavations
- Surrounding disruption, e.g. construction noise, vibrations
- Surface water, e.g. water level, water quality
- Flora and fauna, e.g. the natural environment, fish
- Air quality, e.g. air quality above ground outside the site
- Cultural environment, e.g. ancient remains, buildings of cultural and historical value that are sensitive to vibrations