At 10 p.m. on Friday, February 1, 2019, the Battery Street Tunnel, which connects the Alaskan Way Viaduct to Aurora Avenue underneath Seattle's Belltown neighborhood, is permanently closed to traffic. The decommissioning of the tunnel allows the Washington State Department of Transportation (WSDOT) to begin the first phase of construction inside the tunnel on February 12. The project includes filling the tunnel with rubble from the demolished viaduct and adding new utility lines. A second construction phase, scheduled for 2020, calls for the topping off and sealing of the tunnel with poured concrete, marking the end of the Battery Street Tunnel's 65-year history.
Opened in 1954, the Battery Street Tunnel was seven city blocks long and 2.7 acres in total size. The initial plan developed by WSDOT was to use crushed rubble from the demolition of the Alaskan Way Viaduct to fill the tunnel to within seven feet of its ceiling. The tunnel closure also would allow WSDOT to rebuild a three-block stretch of Seventh Avenue N at the tunnel's north portal.
However, local interests include vendors at Pike Place Market voiced objections to the original plan. In the months leading up to the tunnel's anticipated closure in early 2019, several proposals were put forward as alternatives to filling it, including turning it into a public park or using it as a site for farming, or retaining it as a transit option with seismic retrofitting measures.
One of the more vocal advocates for an alternative to the landfill option was the group Recharge the Battery. These Belltown residents argued that the estimated $200 million land value of the site made it more suitable for reuse. At one point, 44 different ideas were reviewed by Recharge the Battery, from turning the tunnel into a public swimming pool, to growing mushrooms or worms, or adding a beach and making it a surfing site. A number of options making it a park were also proposed.
By March 2018, Recharge the Battery had settled on a preferred option that offered a combined park space with water treatment and a subterranean farm design. Among those advocates contributing to the group's plan were several members of the American Association of Architects (AIA), including Dave Miller (b. 1944) of the Miller Hull Partnership in Seattle.
Other members of the public called for a continuation of the tunnel as a transportation corridor. Mike Osborn, co-owner of Sosio's Produce in the Pike Place Market, called attention to the negative business impact the closure might have on local vendors: "They're effectively closing us off to our northend customers ... Green Lake, Greenwood, Phinney Ridge, even parts of Queen Anne" (Westneat). Another critic of the WSDOT plan, artist Ed Newbold, echoed the displeasure felt by many in the Market community whose livelihoods depend on public access: "It's a complete waste to take it out ... a grade-separated thruway is practically priceless around here. You saw how hard it was for them to drill new tunnels. And here we're just throwing one away?" (Westneat).
The project planners at WSDOT offered feedback on the cost of alternatives. The anticipated cost to seismically retrofit the tunnel for any of them was estimated in the tens of millions of dollars. WSDOT's overall budget to tear down the viaduct, decommission the tunnel, and rebuild Alaskan Way with connections to Elliott and Westeran avenues was $328.9 million.
The proposals were ultimately rejected by the Seattle City Council, which on March 26, 2018, voted 7-2 to execute an agreement with WSDOT to decommission the tunnel, with the addition that the contractor on the project should determine what fill material would be used to seal the tunnel. The dissenting votes came from Debora Juarez (b. 1959) and Sally Bagshaw (b. 1951), whose District 7 included the tunnel. Bagshaw said that while other uses might have been possible, factors such as timing and cost were barriers. Councilmember Mike O'Brien (b. 1968) of District 6 was blunt in his assessment, a view shared by a majority: "The cost and risks associated with doing that are not warranted at this point" (Markovich).
Northbound traffic in the tunnel was halted on January 11, 2019, when the Alaskan Way Viaduct was shut down. Southbound traffic was allowed to proceed through the tunnel to the Western Avenue exit until February 1, when the tunnel was permantly closed at 10 p.m.
Sealing the Deal
The contractor Kiewit Infrastructure West began work on the Battery Street Tunnel on February 12, 2019; its initial work involved removing the tunnel's utility and mechanical systems, and any hazardous materials. During the week of May 10, workers began filling the tunnel with crushed rubble, beginning at Denny Way, and then working their way southwest toward First Avenue. Construction also focused on the tunnel's north portal at Denny and Auroral Avenue, which was renamed Seventh Avenue N. The grade was filled with concrete, raising the roadway to the same height as surrounding streets in South Lake Union. This allowed for the reconnection of John and Thomas streets as cross streets connecting Seattle Center with South Lake Union.
By August 5, crews had sealed the north entrance and filled the tunnel to within seven feet of the ceiling. The rubble was added from vents on surface streets above the tunnel, and from the south entrance to the tunnel on Western Avenue. WSDOT spokesperson Laura Newborn marked the occasion by highlighting the process to convert the tunnel from transit to infrastructure use: "Essentially, the Battery Street Tunnel is becoming a new utility corridor" (Sundell). As with the rubble addition, the crews used existing access points above to layer in vaults, duct banks, and sewer lines on top of the compressed fill layer. A total of 2,400 truckloads of crushed rubble measuring three inches in diameter or smaller were hauled into the tunnel. More than 15 million pounds of steel rebar from the viaduct were added as new infill.
The process of filling the tunnel with a top layer of poured concrete -- mixed and pumped through surface vents along Battery Street -- was scheduled to begin in early 2020.