Under Pressure

by David J. Berti, P.E., EQE Engineering, Oakland, CA,
Maryam Eshghipouur, P.E., EQE Engineering, Oakland, CA,
John Shamma, P.E., Inland Feeder Project Mgr.; Metropolitan Water District of Southern California, Los Angeles, CA,

Serial Information: Civil Engineering—ASCE, 1999, Vol. 69, Issue 7, Pg. 46-49

Document Type: Feature article


The Arrowhead East and West contracts for the Inland Feeder water conveyance system being built in California consist of 51,500 ft (15,700 m) of tunnels that cross the San Andreas Fault east of Los Angeles. The tunnels reach depths of 2,040 ft (620 m) as they pass under mountainous terrain, and groundwater levels are ass high as 1,100 ft (335 m) above the tunnels. Because the final tunnel liner must resist external groundwater pressures of up to 480 pssi (3,300 kPa) and internal water pressures of up to 100 psi (700 kPa), as well as ground loads and seismic strains, the design team developed a new type of pipe that consists of an external steel cylinder with an inner concrete core that is reinforced on the inside face.

Subject Headings: Tunnels | Water pressure | Groundwater | Pressure pipes | Seismic loads | Seismic design | Reinforced concrete | Water pipelines | California | United States | Los Angeles

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