The federal office building located at 909 1st Avenue in Seattle is an art deco structure built in 1933 on the National Register of Historic Places. The General Services Administration (“GSA”), the federal agency administering this federal office facility, is wondering whether its building will be damaged by shifting soils if the State proceeds forward with the new highway tunnel beneath the building’s foundation.
In a letter dated December 13, 2010, the GSA surmised that because the top of the tunnel may be 75′ below the basement, and near the building foundation piers that the historic building and its occupants might be in permanent jeopardy. The General Services Administration has requested assurances that possible methane gas build ups will be mitigated and requested the Washington State Dept. of Transportation (“WSDOT”) take measures to prevent subsidence of the Federal Office Building. WSDOT administrator Ron Paananen, the State Highway 99 administrator for the project has indicated that the tunnel will be approximately 95′ below the surface at the Federal Office Building site and that his agency and tunnel team will be able to alleviate any of GSA’s concerns.