The area is approximately 300-m from the Rhine River, and groundwater is very shallow. As noted in another NCE article, the contractor constructed 15 dewatering wells when only 4 were approved. Additionally, the pumping rate being used was 750 m^3/hr, or nearly double the 450 m^3/hr it was pumping in December of 2008. Clearly the groundwater is one component of the failure, but it does not appear that there is sufficient evidence to say exactly what role of the groundwater was or if the shoring walls did in fact fail and lead to the collapse of the Cologne historical archives and the deaths of two people.
The Devil’s Slide Tunnel Project was originally scheduled to open at the end of 2012, but it has been delayed slightly to an early 2013 opening. If you look at some recent photos, you can hardly tell that there is anything left to finish. I’ve been following this project since it started, since to me it represents the essence of geoengineering, with important roles played by geotechnical engineers, geological engineers, hydrogeologists, and of course geotechnical contractors and tunneling specialists. I thought it would be interesting to list a few of the posts I’ve written about the project over the years and present a bit of information I only recently learned. Click through for more. [Image: kxyoung on Flickr]