The Jefferson Memorial itself is supported on a network of 600+ concrete piles and drilled shafts that penetrate through soft Patomac River sediments and dredged material into bedrock between 80 and 138-ft below ground. However, the seawall is supported on timber pilings that are estimated to be 65 to 75-ft long, stopping short of the bedrock. The wall has been settling below the level of the adjacent plaza since about 2006 as reported by GeoPrac back in 2007. At that time Schnabel was preparing a report for the National Park Service, but I never heard anything else about it. General contractor Clark Construction Company has been working on a $12.4M repair project that includes constructing a temporary cofferdam, deconstructing the existing seawall while salvaging the historic stone facing, installing 4-ft drilled shafts into bedrock and battered concrete-filled pipe piles to support a new seawall. The project is expected to be completed in the spring of 2011. [Source: Washington Post via ASCE SmartBrief. Image: The Washington Post]
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City of Chilliwack, British Columbia to Pay $18M for Up to 42 Homes On Landslide
The Chilliwack Times reports that the City of Chilliwack will pay 80% of the assessed home value for up to 42 homes in an Eastern Hillside subdivision that are located on a slow moving landslide. The issue was first noticed in 2001 and several homes have had significant damage, but most are currently undamaged. The City denies any responsibility, but it’s legal counsel recommended a settlement. (Photo by Paul J. Henderson, Chilliwack Times)
Normally the geotechnical engineer for the subdivision would be held accountable. But apparently the slip surface is located 30-m below grade, much deeper than borings for a typical investigation for a subdivision. I wonder if there were any geologists consulted? Click through for a Google map view of the area and you can do your own armchair photogeology quarterbacking! Your heart does go out to the people losing their homes, they had no idea. But it could be worse, they could be in La Jolla and be getting squat.