October 5, 2018

Kiewit revising viaduct demo plan

Photo by Benjamin Minnick [enlarge]

Crews will remove the central section of the viaduct, fill the Battery Street Tunnel and connect surface streets near the tunnel’s north portal.

Image from Kiewit document [enlarge]

Kiewit’s initial plan has five crews working simultaneously on three sections of the viaduct.

Kiewit Infrastructure West Co. is revising its demolition plan for the Alaskan Way Viaduct in light of last month's decision to permanently close the aging structure on Jan. 11, rather than this fall.

Kiewit's initial plan was based on closing the viaduct this fall, and had demolition finishing in May. No new date has been released for finishing the demo.

The Seattle Times reported on Thursday that Kiewit has subcontracted with California-based Ferma to demolish the viaduct under a $40 million contract.

The DJC received a copy of Kiewit's proposal at deadline and did not have time to review it. According to The Times, Kiewit's 258-page proposal, submitted in April, said crews would tear down the viaduct in 128 days — 142 days faster than the state required — beginning Jan. 2.

But WSDOT spokeswoman Laura Newborn said Kiewit is evaluating a new work schedule that may — or may not — include changes in how it demolishes the viaduct. She said they don't know when Kiewit will submit its final plan, but a notice-to-proceed with demolition is expected when the replacement tunnel opens in early February.

The Times reported that Kiewit would use as many as five different crews working concurrently in three areas to take down the viaduct, with the northern decks near Pike Place Market among the first sections to come down. That would make room for the city to start building the Overlook Walk, the pedestrian connection between the market and the waterfront.

Other parts of the viaduct would come down in three-span sections, with the top decks coming off first, followed by vertical columns and then the lower decks.

Excavators equipped with demolition claws would chip away at the structures.

Adjacent buildings and other structures would be protected by nets, fabric, plywood and mesh.

WSDOT last month said the schedule for opening the tunnel this fall didn't pan out, and there were some concerns that preparation work would affect holiday shopping and other events downtown.

Kiewit was picked in May to demolish the viaduct under a $93.7 million design-build contract. The work area covers 1.4 miles, from South Dearborn Street to Battery Street Tunnel, and includes removing ramps at Columbia and Seneca streets.