Capitol Hill Seattle when to the, well, Capitol Hill station 90% open house. There are a few slides of the presentation, and the obvious question: what happens to all the dirt that gets removed for the underground station?

10 Replies to “Capitol Hill Open House”

  1. I would have thought the obvious solution would be to use rail to pull dirt out of there. Rail cars could carry much more than dump trucks, and you could tow it to much less dense areas. I wonder if there are any spots where Link rail touches regular rail lines* – then we could move the dirt further and more efficiently.

    Of course, there are probably technical reasons why you can’t run a train full of dirt through the bus tunnel. But it sure sounds easier than using trucks.

    * There must be – how else do they deliver new trains?

    1. I’ve been in the London Underground in the late evening and seen one of their “Engineers Trains” roll through a station loaded with ballast, rails, etc. It CAN be done, and is done , but the will to do it has to be present. In Seattle? I think not.

      I believe the LINK cars are delivered by (gasp!) truck, are they not?

    2. The LRV’s are delivered by low-boy semi trucks to Seattle during early morning hours from Everett and they come on ship from Japan.

  2. No. You simply can’t add any sort of heavy rail to the Cap Hill street infrastructure so running spoil trains off the hill isn’t an option.

    However, other than for the trucks removing the fill from the cut and cover station excavation, ST could have stuck to their original 2 TBM plan and removed the tunnel spoils at Husky Stadium via the excavated tunnels. This isn’t any different than what was done with the Beacon Hill tunnel (all spoils removed at one end) although the distances are longer.

    The longer distances might favor muck carts as opposed to a conveyer system, but it would certainly be doable. Removing the spoils at Husky Stadium also creates an opportunity to ship them out via a barge instead of using trucks and city streets. This would be very energy efficient and would also create an opportunity for sea disposal of none contaminated soils.

    However, when ST went to a 3 TBM plan then really needed to use trucks for the Cap Hill-to-stub tunnel segment. I personally don’t think this will be that big of a deal. I’m willing to bet that the total number of trucks won’t be that high compared to existing vehicle traffic on Olive and Denny.

    Just my 2 cents worth.

    1. //can’t add any sort of heavy rail to the Cap Hill street infrastructure// I was talking about through the tunnel in the other direction – through the bus tunnel. I have no idea if this would work out from a staging perspective (are the tunneling toward the bus tunnel or away?), it was just a thought.

      2. Interesting idea, but since the bus tunnel will be used for light rail 20 hours a day, that leaves only 4 hours each night to tunnel toward Cap Hill. I don’t think you want to deal with trains of tunnel muck going through the station as you’re waiting for the next Link or bus to pick you up.

      3. They are tunneling from Husky Stadium southward, and from Cap Hill Station southward — spoils of course flow northward behind the southerly moving TBM. Hence removing spoils via the existing bus tunnel is not an option.

        I still think the best option for removing spoils at Husky Stadium is via a barge, but trucking spoils from TBM 3 at Cap Hill shouldn’t be that big a deal anyhow.

      4. The Army Corps of Engineers is already having trouble operating the locks without lowering the level of lake washington. Plus, where are the spoils going? We can’t just dump them in the water anymore.

      5. I disagree.

        Shipping by barge would require very few movements compared to trucking, and dumping at sea is still allowed – even for dredgings that are typically much more contaminated then anything we are talking about here.

        Yes, ST would need to verify that the spoils were clean (no jet grout), but that is the same as what they had to do for the BH tunnel. And they might need to adjust their polymer mix.

        The locks shouldn’t be a problem – we aren’t talking about a lot of movements here and they still spill water over the dam for most of the year.

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