Design and Construction of a Deep Excavation for the Lake Mathews Outlet Facilities Project
Abstract
The Lake Mathews outlet facility, operated by the Metropolitan Water District of Southern California, serves as one of the prime distribution sources of Colorado River Aqueduct water for Los Angeles, Orange and Riverside Counties servicing a population of 8.4 million. The seismic vulnerability of the existing outlet tower at Lake Mathews reservoir necessitated the design of a new outlet facility to assure serviceability of the facility following a major earthquake. One of the key components of the new facility is a 35 m deep excavation required for the construction of a new outlet tower. The excavation is entirely within highly weathered to fresh, blocky granitic rock. Construction of a 7 m high sheetpile cofferdam permitted excavation to proceed in-the-dry, and a comprehensive grouting program was performed round the excavation to control water inflows.
The performance of the excavation was monitored with slope inclinometers and piezometers and by optical survey techniques and visual observations.
2002
Mike McRae
Jacobs Associates, San Francisco, CA,
Steve Dubnewych
Jacobs Associates, San Francisco, CA,
Joel Mona
Metropolitan Water District of Southern California, Los Angeles, CA,
Lilly Shraibati
Metropolitan Water District of Southern California, Los Angeles, CA,