Highway 99 tunnel 140 results

Highway 99 tunneling update: First the barge, then a sinkhole

January 13, 2016 4:10 pm
|    Comments Off on Highway 99 tunneling update: First the barge, then a sinkhole
 |   Alaskan Way Viaduct | Highway 99 tunnel | West Seattle news

4:10 PM: More news today from WSDOT, the day after the Highway 99 tunneling machine had to stop while they sorted out a problem with the barge that was collecting excavation spoils. The barge problem isn’t fixed yet, but they brought in some trucks, and digging resumed. Then came a sinkhole. Here’s the WSDOT update sent this afternoon:

Seattle Tunnel Partners resumed mining Tuesday evening, using trucks to remove excavated material while they continued working to resolve an issue with a soil-removal barge. STP crews resumed excavation at 7 p.m. Tuesday.

(WSDOT graphic)
Approximately two hours later, a sinkhole developed within STP’s work zone near South Main Street, about 35 feet north of the access pit. It is located more than 100 feet south of the cutterhead’s current location, in ground that crews mined through last week. STP filled the sinkhole overnight with 250 cubic yards of concrete.

This section of the tunnel drive is protected by an underground wall built by STP before tunneling. The wall was designed to isolate ground movement and protect the nearby Alaskan Way Viaduct. A manual survey of the viaduct conducted after the sinkhole developed found no movement. WSDOT and STP will continue surveying and monitoring the ground, viaduct, utilities and other structures.

The cause of the sinkhole is still under investigation. STP is analyzing the portion of the tunnel that crews have excavated since mining resumed. There is no indication that any other locations have experienced ground loss.

STP is reviewing their daily operations as a result of this incident. Immediately they will enhance monitoring protocols by requiring crews to manually verify the amount of soil removed during excavation of each ring.

The protocols STP outlined to enhance monitoring were used in the first 1,000 feet of tunneling and WSDOT is disappointed they were not used when STP restarted tunneling in December 2015. STP has several hundred feet of mining before they reach the next planned maintenance stop. Before leaving the maintenance stop, STP’s operational protocols will undergo an additional review by an expert to assure public safety.

STP has temporarily stopped mining to prepare the muck storage pit to receive excavated material. They plan to resume tunneling this week using trucks to remove excavated material. …

Safety remains our top priority as we work to replace the seismically vulnerable Alaskan Way Viaduct. We expect STP to further investigate this incident and take the appropriate corrective action as they continue to build this important project.

ADDED 6:31 PM: We asked WSDOT’s project spokesperson Laura Newborn about the sinkhole’s size: “According to Chris Dixon, the dimensions of the sinkhole were 35 feet long, 20 feet wide and 15 feet deep.”

Video: Alaskan Way Viaduct tunnel bill signed into law

(looking through the aquarium’s front hall, back at the crowd gathering to watch)
ORIGINAL 2 PM REPORT: We’re at the Seattle Aquarium along with a few hundred political, business and community leaders to watch Governor Gregoire sign the Alaskan Way Viaduct deep-bored tunnel bill into law. The event’s scheduled to start in a few minutes; West Seattle-residing political leaders scheduled to be here include King County Council Chair Dow Constantine (who we’ve already seen) and Mayor Nickels; political theater outside included anti-tunnel mayoral challenger Michael McGinn talking with reporters, calling this a multibillion-dollar boondoggle and saying it’s not too late for the city to pull out. More as it happens.

2:23 PM UPDATE: The speeches are under way before the actual signing. After the mayor spoke (iPhone photo above), the governor said it took “guts” for legislators to approve this. To those who say it can’t be done, she said bluntly — “Watch us.” She opened by declaring, the era of The Viaduct “is over.” For emphasis, she repeated it: “It’s over. It’s over.” And she went on to say it would have been hard to anticipate a year ago that this history-making day would arrive. She stood at a podium next to the aquarium’s fish-filled wall, with about 20 political leaders surrounding her, and acknowledged many others, including members of the Stakeholders’ Advisory Committee who reviewed options over more than a year (though ultimately, their process ended with a recommendation different than the one proceeding now, West Seattle’s SAC reps Vlad Oustimovitch and Pete Spalding both support the deep-bored tunnel).

(WSB video of the bill-signing, added 2:46 pm)
2:31 PM UPDATE: The governor just signed SB 5768 – the tunnel bill – into law. A long round of applause followed. Everyone here has just been invited to a champagne reception – as for us, we’re catching the 3:20 King County Water Taxi back to West Seattle. Looks like more bill signings are ensuing here at the Aquarium as well. Meantime, the state hopes to start building the tunnel next year – to finish it in 2015 – and to keep The Viaduct up, as long as it’s deemed safe, until after the tunnel opens, at which time it would be torn down.

3:02 PM UPDATE: Official statement from Council Chair Constantine, just e-mailed (note he’s in our video):

“I was honored to join Governor Chris Gregoire for today’s signing of Senate Bill 5768, the legislation to fund the replacement of the Alaskan Way Viaduct with a deep-bore tunnel and surface roadway improvements.

“First, I think we have crafted a creative solution to a longstanding problem. A new elevated freeway would not have been an acceptable solution. I am glad we have moved beyond the antiquated practice of forcing freeways through cities. The Alaskan Way Viaduct has long been an ugly, noisy wall separating downtown from the waterfront. Its removal is a first, necessary step in reconnecting our central city.

“Secondly, I am proud to have been involved in helping to negotiate this solution. I made many trips to Olympia over the last year to meet with Governor Gregoire, former County Executive Ron Sims, Mayor Greg Nickels and legislative leaders as part of the Viaduct Oversight Committee. The deep-bore tunnel and a surface boulevard—combined with improvements to the Spokane Street Viaduct and the creation of a new stadium interchange for State Route 99—will maintain access for West Seattle and South King County residents to and through downtown Seattle. And, critically, because the tunnel will not share the alignment of the old viaduct structure, we also have the opportunity to maintain traffic on the SR 99 corridor during construction.

“I support this solution and will work to implement it.

“The challenge to Seattle and King County is to provide the other surface and transit improvements needed to make local transportation work. We now must consider how this work will be funded, how quickly it can be implemented, and how we will be able to sustain the needed transit service in the future.”

Adding one other clip from the event – the governor’s message to tunnel skeptics – may still be processing so please be patient:

One such skeptic, mayoral candidate Michael McGinn – we talked with him outside the event – will add that later.