The groundwater barrier for the tunnel under the new runway has been installed using a method known as jet grouting. Jet grouting creates a cement wall below the ground surface surrounding the entire excavation. The process is designed to dramatically reduce the amount of groundwater getting into the construction site and therefore to reduce the amount of water that has to be pumped away. As a result, little if any impact to nearby groundwater levels is likely. To be absolutely certain, the MAC has implemented an aggressive monitoring
program to measure the amount of water extracted from the construction site and to ensure the development does not pose a threat to surrounding groundwater or surface water resources. The monitoring program is being conducted in cooperation with the Minnehaha Creek Watershed District and the Minnesota Department
of Natural Resources. Both agencies have reviewed the construction methods and have issued permits for the construction and water control activities. Currently, the jet grout barrier has been completed, the construction site inside the barrier has been dewatered, and excavation for the tunnel is underway.

For further info go to;
http://www.mspairport.com/Airport_Expansion/Tunnel_Construction/tunnel_construction.asp