The Loetschberg Basis Tunnel is completed and the first train rode through it. This tunnel together with the Gotthard tunnel are the two main tunnels through the Alps in Switzerland, connecting the north (Germany) with the south (Italy). The Gotthard tunnel is still under construction and will not be completed for another few more years.
The Loetschberg tunnel is about 35 kilometers long, and will be used for cargo trains putting trucks on the train, and for high speed passenger trains. Cars will still go over the mountains. Before the construction about 1.5 million trucks travelled through Switzerland in north-south direction. After completion, the number is expected to drop to 650,000. Besides these environmental savings, the ride through the tunnel will save time as it is twice as fast as the ride over the mountain and will be cheaper than the truck prices for truck companies
How is this related to water? — As any tunnel they had huge water inflows at various stages of drilling, and there is a pretty neat water collection system in place now for the normally infiltrating groundwater.
In 2003 I was part of a field trip to the south portal in Raron, Switzerland. We saw the drilling machine in action, and the geotechnical lab and the rock-recycling facility.