Feds have safety concerns about viaduct tunnel Letter details worries about possible structural damage to federal building

Uncle Sam has some problems with plans to run the tunnel replacement for the Alaskan Way Viaduct under a downtown building owned by the federal government.

The General Services Administration on Dec. 13 wrote a letter to the state Department of Transportation, citing several issues about the tunnel route following the publication of a draft environmental impact study. PubliCola first reported about the letter Monday.

The federal government owns the Federal Office Building at First and Marion. In the letter, the GSA cites worries the current tunnel route beneath the surface "place both this historic building and its occupants in permanent jeopardy." There are concerns about structural damage and "methane gas build-up" that was discovered in the space between the ground and parking level floor slab of the federal building.

"What is the proposed method for monitoring and mitigating any methane gas-build up within the tunnel and specifically around the Federal Office Building?" the letter asks.

As of right now, the federal government has not granted permission to dig under its property until all its concerns are addressed.

"We have posed a number of questions to the State of Washington regarding the impact of the tunnel project on our property. We are working with the State to obtain answers to these questions and once we receive the answers, we will be able to provide a response to the State," Ross Buffington, spokesman for the GSA, Northwest/Arctic Region, told seattlepi.com.

Speaking to the Seattle City Council Tuesday morning, Ron Paananen, who heads up WSDOT's tunnel team, said the state had met with federal officials after the Dec. 13 letter was sent.

"We believe we can satisfy all of their concerns," he said. "The letter was a good indication of their concern to protect federal property, we take that seriously."

Paananen said now that there's a specific plan and contractor it will be easier to address federal questions.

Earlier this month state officials signed a nearly $1.1 billion contract to build what would be the world's largest diameter deep-bore highway beneath Seattle.

Construction on the 1.7-mile tunnel, which can't begin until approval by the federal government, is expected to begin later this year. Eventually, a 57-foot diameter boring machine would burrow beneath downtown, starting from Alaskan Way in Sodo, and lay the framework for a tunnel that will have two road decks and be the world's largest soft-ground tunnel when it opens in 2015 or 2016.

Seattle Mayor Mike McGinn has objected to the tunnel plans, specifically concerns about potential cost overruns. A provision in state law, which many believe to be unenforceable, says city taxpayers would have to pick up the costs of any overruns.

Aaron Pickus, a spokesman for McGinn, said the mayor's office was unaware of the correspondence between the federal government and the state regarding the Federal Office Building.