Tale of two pits: Highway 99 tunnel-machine rescue update; Murray CSO tank site overview

| Transportation | Utilities | West Seattle news

Whole lot of digging going on around the city these days. Two new views:

TUNNEL-MACHINE RESCUE: WSDOT says digging has officially begun for the pit they’ll use to pull up the Highway 99 tunnel machine’s cutting head for repairs – the photo is a screengrab from one of their live construction cameras. Tons of info in this update. The pit will be 120 feet deep, which is twice as big as the West Seattle pit we’re updating next:

OVERFLOW TANK PIT, HALFWAY THERE: Last Wednesday night, in our coverage of the Morgan Community Association‘s quarterly meeting, we reported the county’s update on the excavation by Lowman Beach: They’re halfway to what’s expected to be a 60-foot-deep pit for the million-gallon Murray Combined Sewer Overflow Control Project storage tank. (It’s known as Murray after the nearby street, which also is namesake for the pump station beneath the southeast side of Lowman Beach Park.) So we went over for a look (map). We’re also checking on whether the delayed start of the extra digging sessions on Saturdays means a delayed end date.

ADDED 3:28 PM: According to county Wastewater Treatment Division spokesperson Doug Marsano, “Crews are making good progress – they’re over 40 feet down now (about 2/3rds of the way) – but the rains forecasted for this week could hinder their progress. Currently, the project team expects to work 2 more Saturdays, extending into early November.”

Random October 20, 2014 (1:35 pm)

That’s the pits!

joezaloom October 20, 2014 (1:52 pm)

groan…

SGG October 20, 2014 (2:39 pm)

So let’s get this straight. They stopped digging the tunnel in December last year. And now today, October 20, they announce that they are “beginning” the pit to go down and see what went wrong? What have they been doing for 10 months?

WSB October 20, 2014 (2:44 pm)

First they spent some months coming up with a repair plan:
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https://westseattleblog.com/2014/06/how-highway-99-tunnel-machine-will-be-dug-up-broken-down-put-back-underground/
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Then other logistics. We haven’t covered it blow-by-blow. But there was other logistics (etc.) info when the new state Transp Sec’y and tunnel project boss spoke to the WS Transportation Coalition:
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https://westseattleblog.com/2014/06/viaduct-closures-tunnel-travails-and-more-state-transportation-boss-lynn-peterson-west-seattle-transportation-coalition
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including how much they’ll be fining the contractor if deadlines are missed.

workdowntown October 20, 2014 (2:50 pm)

Any idea how they will get the bulldozers out of the Lowman pit?

WSB October 20, 2014 (3:01 pm)

Now THAT is an excellent question. I was going to add some extra info here anyway. Let me see if I can get an answer!
- WSB October 20, 2014 (3:57 pm)
  
  Yup. From Doug Marsano @ the county: “Contractors will use a crane to get the excavators out. The extraction crane is a bit bigger than the one parked on site now and much stronger.”

ChefJoe October 20, 2014 (3:53 pm)

Probably something like this, except hopefully the crane is setup so as not to fall in. Drop any extra counterweights and thread some hoisting belts through the tracks.

http://www.bing.com/videos/watch/video/crane-crashes-in-on-bulldozer/208iuyfi

workdowntown October 20, 2014 (4:25 pm)

Crazy video! Thanks for the info.

Trileigh October 20, 2014 (4:29 pm)

Funny you should ask. I just stopped by there this afternoon to ask the guys that same thing. As TR says, they told me they’d just hoist them directly out of the pit. Since I’m really eager to see that, I asked when it would happen, and they said sometime next week. THAT should be pretty interesting!

CarraigNaSplinkeen October 20, 2014 (9:02 pm)

workdowntown: maybe the answer is in “Mike Mulligan and His Steam Shovel.”

heather October 20, 2014 (9:19 pm)

I support the tunnel but I was talking with an elderly friend of mine the other day who is against it. I asked why and she told me that her mother, before she passed, remembered when Seattle was “filling in” that area… and how as a young woman she watched them pile up the old streetcars and steel streetcar tracks and bury them… under the soil… right where Bertha’s planning to dig.
:(

Andtos October 20, 2014 (11:05 pm)

Why is there only one excavator digging out Bertha? They should have three working around the clock to get that hole dug. All those unemployed Virgina miners could dig this tunnel faster than Bertha. I feel like this whole project is just one misstep after another.

WSB October 20, 2014 (11:10 pm)

That was a framegrab from this morning … if you follow the camera link, looks busier right now:
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http://www.wsdot.wa.gov/projects/viaduct/Traffic/ConstructionCam

Paul October 21, 2014 (6:33 am)

What you don’t see in the pictures of the SR 99 pit is the ring of concrete piles they built around the pit. They will keep the sides of the pit from collapsing into the hole. It looks like King County did something similar at Lowman Beach.

slatsbob October 21, 2014 (7:38 pm)

Those are called “secant piles” Standard construction method for shoring in advance of excavating, especially when ground water is an issue.

Interesting to read some of the ignorant rants about SR 99 above. Relax people … it will get built.

GUA8Avenger30Mike October 22, 2014 (1:51 pm)

Fascinating and cool progress pix and video. The explanations are very helpful. Not very long ago we would have all been in the dark about the problem and solutions. Thanks WSB!