California Bay Delta tunnel project
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December 3, 2015: Conceptual design is complete for nearly 70 miles (112km) of bored tunnels that form the Phase 1 California Water Fix of the planned $14.9 billion California Bay Delta Water Conveyance Project to transfer fresh water from the Sacramento River under the delta to pump stations in the south for onward transportation via existing conveyance infrastructure to the populations of central and southern California.

The Design and Construction Enterprise, a new entity created by the California Department of Water Resources, will be advancing further design and construction work packages for the California Water Fix program once the environmental assessment process for the program is completed in mid-2016.

A six-year tunnel construction phase, split across a proposed six construction packages, is scheduled to begin in 2019.

References
Mega water tunnel plan for California - TunnelTalk, February 2010
Governor supports mega water tunnels project - TunnelCast, July 2012
Changes to reduce mega Delta project impact - TunnelCast, August 2013

Snapshot

California Bay Delta tunnel project

Sterling Noren reporting for TunnelCast
Project: California Water Fix, USA
(Bay Delta water conveyance tunnels)
Total Cost: $6.8 billion of underground
construction on a total US$14.9 billion project
Project Scope: 70 miles (112.5km) of water
  conveyance tunnels
12–13 access shafts of depth
  150ft (45.7m)
Water pumping infrastructure
Geology: Unconsolidated soft ground,
  including peat
High groundwater table
North Tunnels: 10 miles (16.1km)
20–28ft (6.1–8.5m) i.d
Main Tunnels: 2 x 30 miles (48.3km)
40ft i.d.
Tunnel depth: 150ft (45.7m), pressure up to
  4.5bar at invert
Excavation
method:
10–12 TBMs up to 45ft (13.7m)
  diameter
Tunnel lining: Single pass concrete segmental lining 8 segments + key
Interviewed: John Bednarski, Section Manager,
Metropolitan Water District,
Southern California