A two month project to prepare the soil of the western slope of Capitol Hill for light rail tunneling is planned to start today, according to a construction alert from Sound Transit issued on Friday. According to the document provided by the transit agency, eastbound Pine near the Paramount will be ‘temporarily’ closed during the work. We’re asking ST for some clarification about what that will mean but you can find detour and bike route information below. We’ll also ask why there was such short warning on this project on a significant route between the Hill and downtown.

The project description below lays out eight weeks of “jet grouting” work, a process that was recently completed at the Broadway light rail station construction site and involves the application of “cement, cement kiln dust, calcium chloride or other high pH materials” into the soil to improve the performance of the tunnel boring equipment. As we’ve reported before, the process isn’t recommended to be done during rainy periods so Sound Transit’s contractor is likely hoping some sunshine or, at least, no more August rain.

 

Preparations for Connecting Downtown Seattle Light Rail Tunnels to Capitol Hill Tunnels for University Link Construction
Jet Grouting on Pine Street

Late next year, the first Tunnel Boring Machine (TBM) will arrive at Pine Street from Capitol Hill. When it arrives the machine will be disassembled and trucked back to Capitol Hill to dig the second tunnel. Sound Transit’s contractor is about to begin the preparations for the arrival of the machine. One of the first major activities is jet grouting – a ground improvement technique that utilizes a strong, cementitious material to stabilize the ground and prepare the area for the launch and extraction of the tunnel boring machine.

As early as Monday, August 2, and lasting for approximately 2 months, Sound Transit’s contractor, JCM ULink Joint Venture, will be conducting jet grouting activities in the Pine Street area east of the Paramount Theatre. Work will take place in the triangle-shape lot (highlighted in map to the right), as well as in the eastbound lane and south sidewalk of Pine Street between 9th and Boren avenues.

The following activities will begin on Monday, August 2:

• Sidewalk closure on the south side of Pine Street between 9th and Boren avenues. A pedestrian detour will be in place
• Driveway preparations and cut-ins for entrance into triangle-shaped lot for jet grouting equipment
•  Tree and planter removal

 The following activities will begin on Monday, August 9:

• Temporary closure of Pine Street’s eastbound lane between 9th and Boren avenues. Two lanes of westbound traffic will remain open.
• Detour for eastbound Pine Street (see map on reverse):
  Motorists traveling eastbound on Pine Street will be detoured right onto 9th Ave

• Left onto Pike Street

• Left onto Boren Ave to return to Pine Street

• Recommended bicycle detour (see reverse for details)

Hours of construction activities will be from 7:00 a.m. to 7:00 p.m. Monday through Friday, with possible weekend activities. Access to businesses and for deliveries and sanitation pick-up will be maintained at all times. Moderate to loud noise from the drilling activities is anticipated.