Project–At–A–Glance

Calaveras Dam
Replacement

WSIP Region
Sunol Valley

Location
Boundary of Alameda & Santa Clara Counties

Construction Start
June, 2010

Construction Finish
December, 2013

Current Status
Design, Environmental

Project Cost
$334M

Calaveras Dam
Reservoir Upgrade

Project Complete
July, 2006

Project Cost
$2M

Calaveras Dam, which stores drinking water in the SFPUC’s largest local reservoir, is located within the Alameda Watershed.  The existing earthfill dam is located near active earthquake faults and has been deemed seismically unsafe by the California Division of Safety of Dams.  The SFPUC lowered water levels to less than 40% of its capacity in the reservoir in response to seismic concerns in 2001. The SFPUC proposes to rebuild the dam to restore the reservoir to its historic level of 96,850 acre-feet. The proposed replacement Calaveras Dam would consist of a new earth- and rockfill dam of the same reservoir capacity as the existing dam and built immediately downstream of the existing dam.

Description
Proposed Project elements include:

• Constructing a new 210-foot-high earth and rock fill dam designed to accommodate a maximum credible earthquake on the Calaveras Fault. The dam will be constructed immediately downstream of the existing dam and will have a crest length of 1,210 feet, a base thickness of 1,180 feet, and a crest thickness of 80 feet. The total volume of the dam will be approximately 2.8 million cubic yards.
• The materials for construction will primarily originate from onsite sources, while surplus excavated material will be placed at disposal sites around the rim of the reservoir.
• The existing spillway will be removed, and a new spillway and stilling basin will be constructed.
• A new intake tower and shaft will be constructed and new conduits to accommodate water releases from the reservoir in high and low capacities to Calaveras Creek.  . The
• The existing dam will largely remain in place. The downstream face will, however, be partially removed and regraded and a channel will be excavated through the dam to form the approach to the new spillway.

Project Completed: July, 2006
As a result of restricted reservoir operating levels mandated by the California Division of Safety of Dams, the reservoir experienced algal blooms that could adversely impact raw water quality and subsequently limited the ability of the Sunol Valley Water Treatment Plant (SVWTP) to deliver water of suitable quality. The purpose of the project was to enhance interim operations and improve raw water quality prior to completion of the Calaveras Dam Replacement project.

Description
The project consisted of installing an oxygenation system and associated equipment near the dam to limit the negative effects of algal blooms and promote a healthier fish habitat. The system will continue to be usable following completion of the Calaveras Dam Replacement Project.

Note: Schedule and cost information shown may vary from the 2007 Approved WSIP Schedule and Budget. The information shown reflects the current forecast information published in the latest WSIP Quarterly Report.