Topic:  Calaveras Dam Replacement Project

Berlogar Stevens & Associates assisted Kiewit in bidding the Calaveras Dam replacement project in the summer of 2011. They reviewed the construction design documents, including reams of geotechnical, geological, and geophysical reports and data. The project consists of building a new zoned earth and rock fill dam just downstream of the existing dam. The reservoir provides approximately half of the Hetch Hetchy Regional Water System's local Bay Area water storage. The existing dam was deemed unsafe in 2001 due to seismic concerns and the water level was lowered 50 feet. The Calaveras fault zone is located about 1,000 feet from the existing dam and the dam is expected to experience peak ground accelerations of 1g.

The existing dam was constructed 85 years ago using a semi-hydraulic fill method of construction. The challenges in bidding and constructing this dam include:
- determining the amount of blasting required for construction,
- earthwork and tunnel construction difficulties within melange bedrock, which can be described as chunky peanut butter or jello with fruit.
- an existing landslide on the right abutment,
- presence of naturally occurring asbestos in the bedrock,
- providing import rock and gravel for the filter rock with very strict quality requirements.

The dam project was awarded to Flat Iron Construction for approximately $260 million, Kiewit was the second lowest bidder with a bid less than $10 million higher. The total project costs are estimated to be $416 million, construction began in September 2011 and is projected to be completed by August 2015.  See field notes for more information.

View site plan <click here>

Speaker:  Bill Stevens, Principal at Berlogar Stevens & Associates