Client:
San Diego County
Water Authority

Project Duration:
1998-2003

Olivenhain Dam Project Value:
$203 million

Design Services:
Preliminary design, extensive site geologic/ geotechnical field studies; seismotectonic design; instrumentation design; foundation design including pressure grouting for seepage control; roller compacted concrete design; flow control facilities

Construction
Support Services: Administration of the project labor
agreement (PLA),
site coordination of the Olivenhain projects, development and administration of
an owner controlled insurance program (OCIP)

The Olivenhain Dam is a critical asset in San Diego's future water supply. The dam is part of the San Diego County Water Authority's $827-million Emergency Storage Supply Project, which protects the region by increasing the amount of water available in the county in emergency situations. A drought or major earthquake could interrupt San Diego's water supply for up to six months, and some communities could be without water within 3-4 days. The Olivenhain Dam and Reservoir will ensure that San Diego County has stored up to 24,000 acre-feet of safe water in the event of such an emergency.

Vertical upstream face of Olivenhain Dam. Foreground shows a portion of the RCC conveyor delivery system. Background is the intake and outlet structure.

The Olivenhain Dam is an impressive engineering accomplishment. Parsons, in partnership with Harza Engineering, designed the dam. Preliminary design was completed within eight months. Parsons-Harza conducted extensive site geologic/geotechnical field studies to support the dam's seismotectonic design. The dam was designed to withstand and continue to function after an earthquake with a magnitude of 7.2 on the Richter Scale.

Olivenhain is the first roller-compacted concrete (RCC) dam in California. At 318 feet, it is the highest RCC dam in the U.S. Roller-compacted concrete is similar to and as strong as traditional concrete, but is less expensive, requires less water, and is much stiffer when placed. An RCC dam can be built in less than half the time it takes to build a conventional concrete dam.

Because the dam had to be completed by late summer of 2003, the plans were designed and work was conducted on a fast track schedule. The Parsons-Harza implementation plan entailed constructing the dam and appurtenant facilities through four separate, sequenced contracts, allowing some degree of overlap.

Olivenhain Dam's intake and outlet structure under construction.

The construction of the dam is virtually complete with the recent "topping off" of the dam with RCC on October 31, 2002. The various remaining components (the inlet/outlet tower, dam's crest roadway, downstream flow control facilities, mechanical and electrical work) continue to move forward for a summer 2003 completion.

Environmental mitigation requirements have also been incorporated into design. A spectacular 750-acre open-space park and recreational area will surround the dam and reservoir. The reservoir will offer 17 miles of hiking, mountain biking, equestrian trails and viewing points. The wildlife and natural resources on this reservoir are all closely monitored and will be preserved for generations to come. The face of the dam will be stained with a color that blends into the natural surroundings of the area.

Dedication of the Olivenhain Dam is scheduled for summer 2003, when filling of the dam will begin. It will take approximately one year to fill the dam's reservoir with an anticipated start date of August 2003. To fill the dam, 14,000 feet of 78-inch diameter, welded-steel pipe was constructed between the Water Authority's Second Aqueduct and the Olivenhain Reservoir. The water in the aqueduct is imported via the Colorado River Aqueduct and the State Water Project's California Aqueduct.

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