Seattle’s big demolition spectacle: How crews plan to pulverize the Alaskan Way Viaduct

Visitors to the Seattle waterfront will hear the crunch of breaking concrete this February, while demolition equipment pivots through clouds of dust and mist, flexing spiked jaws that will munch the six-story-high columns and slice through steel Rebar.
Briefings on Alaskan Way Viaduct demolition
Three neighborhood briefings by WSDOT and Kiewit are scheduled:

Tuesday: 5 – 8 p.m.; Waterfront Space; 1400 Western Ave.
Wednesday: 11 a.m. – 2 p.m., Waterfront Space, 1400 Western Ave.
Monday, Dec. 10: 5 – 8 p.m., Seattle Center, Armory Loft Room 2
305 Harrison St.

For as long as 5 1/2 months, work crews will demolish the Alaskan Way Viaduct, working on three to five sections at a time. Reinforced fabric shrouds will be hung from frames that contractors can move along the route to protect building walls and windows.
Kiewit Infrastructure West, prime contractor for the $75 million job, has settled on its final strategy for the work, which senior operations manager Phil Wallace outlined in an interview last week. The Washington State Department of Transportation (WSDOT) will announce details Tuesday and hold three public briefings.
Sign up for Morning Brief Delivered bright and early weekday mornings, this email provides a quick overview of top stories and need-to-know news. “What you’re going to see is the waterfront opening up, and by June you’re going to see a pretty wide open waterfront, without the viaduct there,” said Laura Newborn, a WSDOT spokeswoman.
Barring an Anchorage-magnitude quake, Seattle will see the 2009 wish of Gov. Chris Gregoire fulfilled: “We want to take the viaduct down, before Mother Nature beats us to the punch.”
This may provide the city’s greatest demolition spectacle since 2000, when pyrotechnicians imploded the Kingdome in only 17 seconds. More recently, in 2011 the state removed the southern mile of the viaduct over Sodo in nine days, but the governor missed her self-imposed 2012 deadline to remove the 1.4 miles downtown. The 65-year-old Viaduct will be replaced by a new four-lane Highway 99 tunnel, along with Sodo and South Lake Union interchanges, scheduled to open the week of Feb. 4. The program costs at least $3.3 billion, funded mostly by gas taxes.
Demolition equipment will clutter the waterfront for months. Merchants have complained about summer access. “The waterfront is open for business during demolition,” promises Brian Nielsen, the state’s Highway 99 administrator.
In a new development, Kiewit and WSDOT told business leaders late Thursday they’ll strive to complete all teardowns by June 1, except a couple blocks near Lenora Street and the curve south of King Street, that might remain until July 31. That means the central waterfront would be clear the weekend after after Memorial Day, and angle parking would even be added, said Bob Donegan, president of Ivar’s restaurants. The June 1 target was unveiled in a two-hour meeting with the Seattle Historic Waterfront Association and representatives from Pioneer Square and Pike Place Market, he said.
“We were overjoyed to hear this,” said Donegan, who admits to being infuriated weeks ago, when the state a postponed a fall tunnel opening and its timeline to finish demolition by spring 2019.
Crews will work in sections of two to three blocks at a time. They will generally start by punching decks with jackhammers. Then the concrete beams will be demolished with a crab-claw-shaped tool.Water will be sprayed on the dust to knock it down, and silty wastewater is to be processed onsite, Newborn said. That treatment would be similar to how Seattle Tunnel Partners pumped water into settling tanks, the size of shipping containers, to capture grit before releasing wastewater into the county sewer system.
Kiewit’s demolition subcontractor, FERMA Corp., will begin work over train tracks near Pike Place Market, removing concrete during limited hours to avoid freight and passenger trains using the Great Northern Tunnel.

“That is first-order work for us, so we can get out of the area as soon as possible,” Wallace said.
Soon afterward, the far north end of the viaduct will be removed, Wallace said, so the city can start building the signature Overlook Walk from the Market to Seattle Aquarium. FERMA will bring excavator machines with arms tall enough to reach upper decks, said Wallace. That’s a change from Kiewit’s initial plan to keep old viaduct ramps in place several weeks, so the machines could be driven onto the viaduct decks.
The Columbia Street onramp will be demolished immediately, so the city can complete paving its future two-way bus corridor below, and embark on a new bridge promenade to Colman Dock. A temporary steel bridge will be installed nearby, to maintain walk-on ferry access from First Avenue.
Heavy demolition will be allowed seven days a week from 7 a.m. to 10 p.m., under city noise permits, though truck trips and equipment staging may continue overnight. The loudest jackhammering of up 90 decibels will wrap up at 8 p.m. weekdays and 5 p.m. weekends, according to WSDOT.
Once the viaduct is gone, the $35 million decommissioning of the Battery Street Tunnel will continue into 2020, along with $17.5 million worth of new street connections across lower Aurora Avenue North until 2021, all within the $94 million Kiewit contract. Newborn said contractors will be paid a few million dollars extra, still under negotiation, because of WSDOT’s decision to delay the opening of the new four-lane Highway 99 tunnel until February, which in turn delayed the initial Jan. 2 date to begin viaduct demolition.

Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com; on Twitter: @MikeLindblom. Staff reporter Mike Lindblom covers transportation for The Seattle Times.