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February 8, 2019

WSDOT says crews starting today to demo ramp at Columbia Street

By BENJAMIN MINNICK
Journal Construction Editor

Photo by Benjamin Minnick [enlarge]
The entrance to the Polson Building will remain open during demolition because it’s far enough away from the Columbia Street ramp.

WSDOT opened the new waterfront SR 99 tunnel on Monday and now attention has turned to removing the dilapidated Alaskan Way Viaduct.

Demolition on one of the first pieces — the southbound on-ramp at Columbia Street — is about to begin.

Building owners in the area were told that work could start today — and that the section between First Avenue and the west side of Western Avenue could be gone in a week. Original estimates were up to 30 days.

On Wednesday, workers removed electrical control boxes under the ramp near First Avenue. Yesterday, the city posted 24-hour “no parking” signs on Columbia — effective from today to Feb. 20.

One of the affected properties is the Journal Building, home to the Seattle DJC. Tenants will start using a side entrance on Western Avenue today because the front of the building will be closed during demolition. The Journal Building is just a few feet from the ramp.

Removing the ramp will require around-the-clock “impact” work, which can include jackhammering.

The ramp is coming down first so that the city can convert Columbia Street into a two-way bus corridor between Third Avenue and Alaskan Way.

A report from Kiewit Infrastructure West Co., the project's design-build contractor, said crews removing the ramps at Columbia and Seneca streets will use a slightly different method than they will on the rest of the viaduct. Crews will use small excavators to remove decks, then forklifts and cranes to remove girders. Debris will be lowered to the ground and hauled away.

Kiewit spokeswoman Alex Prentiss said crews will use hoe rams to perforate the deck at strategic locations to make it easier to break up.

When it comes time to demolish the main viaduct, crews will remove the top decks with impact hammers, then remove the girders and columns supporting the top decks using high-reach excavators. A similar method will be used for the lower decks.

Kiewit's demolition subcontractor, Ferma, is bringing a special crane from California for the work.

Prentiss said the crane will be the largest piece of equipment used on the project. The machine is being delivered in seven truckloads.

Prentiss said Ferma designed and built the crane, but couldn't provide more details.

The DJC reported in December that Ferma will pulverize concrete from the viaduct into 3-inch chunks and use them to partially fill the Battery Street Tunnel. About 7 feet of space between that rubble and the tunnel ceiling will be filled with low-density cellular concrete pumped in from surface vents along Battery Street.

Kiewit last year won a $93.7 million contract to demolish 1.4 miles of viaduct between South Dearborn Street and the Battery Street Tunnel. The job includes decommissioning Battery Street Tunnel and connecting roads at the tunnel's north portal.

WSDOT wants to have the central waterfront portion of the viaduct gone by June, the unofficial start of tourist season. The entire viaduct should be gone by August.


 


Benjamin Minnick can be reached by email or by phone at (206) 622-8272.



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