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Follow-ups: FedRep park digging, extra juice for the TBM tunnel boring machine

We followed up on a few items raised in the rabble of the CHS comments. Rabble rabble rabble!

Front loader in the lot this morning
A few guys showed up this morning with front loader. They dug a large hole in the middle of the lot, put a fence around it, then left. Not sure what’s up. Maybe they’re planting mutant giant tomatoes in our soon to be pea patch.

We checked in with the city to see what new drama was unfolding at the FedRep empty lot. Parks department tells CHS that, yes, the landowner was investigating the presence of buried tanks on the property as part of the sales process and that one was found and needs to be dealt with before the sale is complete. The Parks official we spoke to said this likely won’t impact the sales process. We’ll, um, dig in and see what else we can learn about further testing related to the find. In the meantime, you’ll note in the pictures on this posts that neighbors have turned the chain link fence surrounding the lot into a kind of neighborhood bulletin board. Abbie, helpfully, posted a note about the search for the oil tanks. You’ll also see some interesting plastic decorations and a “Future Neighborhood Park!” label. How can CHS compete with that?

This electric upgrade is undoubtedly related to the fact that the tunnel boring machine (TBM) runs on electricity.

The TBM launched at Capitol Hill Station (CHS) will proceed twice — once per each future one-way rail tunnel — from the CHS site down to the Pine Street Stub Tunnel (PSST). All the dirt removed for each tube comes out through the station site.

A brief overall description of the future 3 mile long subway tunnel coming to the neighborhood is an 8 page paper (pdf) prepared for a 2008 tunnel conference. The paper is on a contractor’s web site.

Quoting, “The TBM for the northbound tunnel will be launched first from the CHS box after the bottom slab has been placed. This will allow for construction of the station box while the northbound running
tunnel is mined. Once the TBM reaches the PSST, the TBM will be moved back to CHS and then re-launched to mine the southbound running tunnel.”

Good luck to all involved!

According to Sound Transit spokesperson Bruce Gray, the power upgrade is, indeed, necessary to power the tunnel boring machine, a.k.a the TBM. “After checking in with our construction folks,” Gray wrote, “the short answer to your question is yes, we need more juice at the site for the TBM operations than what we have there today.” Seattle City Light tells us that the lines are temporary and being installed specifically for the light rail station’s construction period. They also tell us that the system will be set up to provide Sound Transit contractors drilling the tunnel with two feeder lines so that there is a back-up should one line fail. City Light says both of those lines will be fed by the Pine substation. Now you know!

  • UPDATE: We also have a follow-up we didn’t even have to dig for. A spokesperson for SDOT sent us unsolicited e-mail with some answers to questions raised in the comments on our recent post about a summer 10th Ave paving project. Take it away Marybeth Turner:

One reader asks why it takes so long to pave 10th from Boston to Miller. The reason is that we will completely reconstruct the roadway from the base up, and pave with concrete which is better suited to support the bus traffic on this street. (This takes a lot longer than grinding down surface asphalt and then applying a new asphalt surface as we do on many city streets.) Also, we will remove and replace the concrete curb on both sides of the street.

Other readers asked why we don’t pave all the way north to Roanoke, and why we don’t pave Boston from  10th Avenue to Broadway. We are aware of the poor pavement condition. Ideally, we would like to reconstruct all of 10th Avenue East from the SR 520 overpass to the turn at Broadway; however, with limited funds, we prioritized the segment through the business district. We plan to reconstruct the other parts of 10th when the funds are available. We are not paving Boston because with limited funds we are giving priority to arterial streets.

Another reader asked for an alternative bike route during construction. We are consulting with our bicycle program staff on this issue.

For project updates, watch the project website at

Questions may be directed to George Frost, (206) 615-0786.  

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Phil Mocek
Phil Mocek
13 years ago

Weren’t we told that part of the justification for the noise variance Sound Transit requested and the City granted was that on-site generators will be needed to provide power to the tunnel boring operation?

From page 8 of DPD’s April 19, 2010, Analysis and Decision (PDF, 256 KB):

Ventilation fans and power generators are needed at the surface to provide fresh air to the workers in the tunnel and a reliable power source for the underground equipment.

Are we intentionally building unreliable new power lines?