Historic Seattle neighborhood inspected for damage after sinking

By Eric M. Johnson SEATTLE (Reuters) - Some 30 buildings in a historic Seattle neighborhood will be inspected for damage after officials determined they sit in a wider area that has sunk as much as 1.2 inches since October amid a $3.1 billion roadway overhaul, officials said on Tuesday. Portions of the Alaskan Way Viaduct and the earth around it have sagged as crews pump groundwater from a deep pit near the highway, clearing the way for repairs to a massive tunnel-boring machine, nicknamed Bertha, which overheated and broke down a year ago. The machine, nearly 60 feet in diameter, was brought in to dig an underground expressway to replace the aging waterfront highway, which was damaged in a 2001 earthquake. While the sinking poses no immediate threat to public safety, officials worry that so much ground subsidence in so brief a time might cause stress-induced cracks and other damage to the highway, buildings and public utilities in the area. The state confirmed through surveys over the weekend that the roadway underwent "uniform" settlement levels of roughly 1 to 1.2 inches, while more worrisome "uneven settlement" occurred near the tunnel access pit. Washington state has hired outside experts to inspect buildings and structures near the construction site and viaduct, pending owners' approval, state Department of Transportation spokeswoman Laura Newborn said. This includes some 30 buildings around Seattle's historic Pioneer Square neighborhood, Newborn said. State officials were still working to determine the exact size of the area affected. On-the-ground surveys will continue this week by architects and structural engineers, and city officials said they were inspecting public infrastructure, Newborn said. The Transportation Department, which has not confirmed the cause of the sinking, said it is working with the contractor, Seattle Tunnel Partners, to develop a plan to stop pumping water if the data shows continued settlement. The contractor aims to resume tunneling by late March 2015 with the goal of opening the underground expressway to traffic in late 2016, despite a year fraught with delays, as part of a broader $3.1 billion roadway overhaul, state transportation officials said. (Editing by Steve Gorman and Sandra Maler)