Access pit excavation is underway
Posted on Oct 20 2014 11:19 AM
Seattle Tunnel Partners has started digging the circular pit (pdf 2.5 Mb) crews will use to access and repair Bertha, the SR 99 tunneling machine. On Friday evening, Oct. 17, an excavator rolled into position to the west of the Alaskan Way Viaduct near Pier 48, where STP stopped tunneling last December after Bertha overheated. There, crews began taking the first scoops of soil from what will become a 120-foot-deep, 80-foot-wide pile-supported pit.
Approximately 20,000 cubic yards of soil will be removed from the pit over the course of excavation. Because a number of other important construction activities are competing for space near the pit, there will be many days when excavation doesn’t occur. Contaminated soil will be hauled by truck or barge to a disposal facility; STP will store non-contaminated soil and use it to fill in the pit after tunneling resumes.
Meanwhile, crews are continuing to lower groundwater in enclosed areas near the machine and prepare for installation of the massive crane that will be used to hoist pieces of the machine to the surface for repair later this fall (simulated image below).
You can watch the pit take shape on our time-lapse cameras. Taken from our south-facing camera, the shot below shows you STP’s progress as of Monday morning, Oct. 20.
- View an animation of repairs narrated by STP Project Manager Chris Dixon (view on YouTube or download WMV file)
- View photos on Flickr
- Seattle Tunnel Partners repair work plan (pdf 4.8 Mb)
- Graphics showing access pit construction (pdf 2.5 Mb)
- Time-lapse cameras of repairs
- Video of crews building the access pit (view on YouTube or download WMV file)
- Video of crews reconfiguring the tunnel launch pit (view on YouTube of download WMV file)
- Brochure of STP's repair plan (pdf 1 Mb)