American Academy of Environmental Engineers

Project Description

Integrated approach

The Olivenhain Project was designed and built to safeguard the San Diego Region from natural and man-made disasters, while minimizing environmental impacts.

The Project’s comprehensive, integrated approach started at the planning phase when a site was selected that had been set aside more than 30 years ago for a water storage reservoir.

One of the largest environmental considerations was the impact on the local residents, some of whom live less than a half-mile from the new dam.

Hundreds of local residents were brought into the Project at the planning phase through a broad-based outreach program, including neighborhood meetings and the formation of the Emergency Storage Working Committee – a 27-member citizen’s advisory group.

The Owners kept the residents involved through design and construction using regular newsletters, meetings, and site tours, and a 24-hour hotline.

One of the largest impacts – the stark appearance of a large concrete monolith – was mitigated through the use of a stain that matched the dam’s downstream face to that of the surrounding topography.

Quality

Schedule was a critical Project issue for the Owners. Due to the emergency storage mission of the Project, the schedule was optimized to make it operational as quickly as possible. A fast-track approach using “construction packages” reduced the overall contract duration by about one year.

Packages allowed site development and dam foundation excavation to proceed on an expedited basis, while detailed dam design, environmental permitting and regulatory review were underway.

By using RCC, the construction schedule was shortened to roughly half that of a traditional concrete gravity dam, reducing the overall cost and minimizing the adverse impacts on the environment (emissions from construction equipment) and local residents (noise, dust, light, traffic, and safety).

More than 1.4 million cubic yards of RCC were produced on site and placed in fewer than nine months, setting world record rates for RCC placement at 16,000 cubic yards in a day and more than 294,000 cubic yards in a month.

More than 2.8 million cubic yards of granite were quarried on site, reducing truck traffic transiting through the local community and reducing use of energy.

Innovation/ Originality

The dam’s many unique design features incorporated a number of innovative techniques, tools and processes including:

RCC zero-slump concrete - a moist concrete with just a minimal amount of water that allows concrete to be mixed and handled like soil. RCC supports heavy construction equipment immediately after placement, allowing uninterrupted “7/24” construction. Conventional concrete requires waiting seven to 10 days of curing before pouring the next lift.
A curvilinear downstream face to minimize stresses within the dam structure under seismic conditions.
Material innovation using an exposed geomembrane liner on the upstream face of the dam to provide water tightness and its ability to move and stretch with the dam during an earthquake. This is the world’s largest application of an exposed geomembrane liner on a dam.
Large shaping blocks -- foundation treatments designed to optimize dam performance during an earthquake. These are the world’s largest foundation replacements using shaping blocks.

Complexity

In San Diego County alone, three dam and reservoir projects proposed in the 1980s failed because of major public opposition.

In addition, any new dam design (including the foundation, structural, and operational systems) must be optimized to meet the large forces induced by potentially catastrophic regional earthquakes.

The Olivenhain Dam utilized a planning process that set new standards for development of new storage facilities in an urban area, while minimizing adverse environmental impacts and maximizing public participation and awareness. In fact, the project team maintained near daily communication with community members throughout the three-year construction period.

The project team used community input on equipment use, blasting and trucking schedules, construction methods, and even the color of the dam (a desert varnish stain minimized the visual impact).

The U.S. Society on Dams subsequently adopted the public involvement methods used for this project as the model for the future planning of dams and reservoirs in the U.S. and has proposed making them the international standard.

Social/Economic Advancement

Emergency Water

The Water Authority’s proactive approach to the environmental process included innovative public partnerships that went beyond legal requirements. Early regulatory agency involvement resulted in both EPA and the USFWS letters of support.

Dedicated in August 2003, the 24,000 acre-foot Olivenhain reservoir provides 18,000 acre-feet of emergency water stored and available to serve San Diego County should a water-supply emergency occur.

A Recreational Resource

As part of the Olivenhain Project, a new 750-acre Elfin Forest Recreational Reserve was created surrounding the reservoir. Wildlife and natural resources at the reserve are closely monitored and will be preserved for generations to come.

Copyright 1996-2005 American Academy of Environmental Engineers - All Rights Reserved. American Academy of Environmental Engineers, Excellence in Environmental Engineering, Environmental Engineering Selection Guide, Environmental Engineer, and Who's Who in Environmental Engineering are all trademarks or registered trademarks of the American Academy of Environmental Engineers, Inc.