Sacramento embedded liner
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Oct 2009: The Upper Northwest Interceptor 1&2 Project (UNWI 1&2) is the first segmental tunneling project in the world to use a PVC corrosion-protection liner embedded in the tunnel segments. Traylor/Shea JV is 14,500 feet into its 3.6 mile drive with 4,664 feet to go before breakthrough into the UNWI 2/3 Transition Structure reception shaft.
Feedback: First use of a steel plate liner embedded on precast concrete segments was for the second Dartford road tunnel in the UK in the 1970s.

Snapshot

First use of embedded line in tunnel segments

Paula Wallis reports for TunnelTalk
Location:
Sacramento, CA USA
Project:
Upper Northwest Interceptor 1&2
(UNWI 1&2)
Tunnel:
3.6 mile x 12ft i.d. diameter
(5.75km x 3.6m)
Contract Value:

$97.3 million
Owner:
Sacramento Regional County
Sanitation District
Contractor:
Traylor/Shea JV
Construction Manager:

Hatch Mott MacDonald
Designer:
URS
TBM:
EPB supplied by The Robbins Company
Completion Date:
Tunneling activities began on January 14, 2009. Excavation was completed November 18, 2009. Project completion is expected in November 2010.