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Calaveras Dam Replacement Project Air Monitoring Results

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Calaveras Dam Replacement Project
Naturally Occurring Asbestos

The replacement of Calaveras Dam will require the movement of more than 7 million cubic yards of rock and earth, a portion of which may contain Naturally Occurring Asbestos (NOA).  Construction activities could cause asbestos fibers to become airborne, which could present a health concern. We have put into place an extensive dust control and air monitoring program to ensure that we are not exposing any members of the public to increased levels of naturally occurring asbestos. We have monitored background air quality levels in the area prior to construction for more than two years. We will continue to monitor air quality at perimeter and ambient air quality monitoring stations and will make the data available on this website.  Protecting the health of our workers and the public is our utmost priority.

Air Quality Monitoring Data

To view the latest air quality monitoring results, click on each monitor number below. Graphs are updated on a weekly basis. There is an approximate 2 week delay on online reporting due to our lab analysis time.

Archival Data

Previous periods that are not included below can be found here. Data from previous periods is presented quarterly.

See map for monitoring locations and Q&A about how to read the graphs and data. Questions? Contact us at or, or call us at (866) 973-1476.

Air Monitoring Station - Perimeter (P)
P1 P3 P4 P5 P6
P7 P8 P9 P10 P11
Air Monitoring Station - Ambient (A)
A1 A2 A3 A4 A5

Project Description
The project consists of building a new zoned earth and rock fill dam immediately downstream of the existing dam. The replacement dam will have a structural height of 220-feet high and is designed to accommodate a maximum credible earthquake on the Calaveras Fault. The dam will have a crest length of 1,210 feet, a base thickness of 1,180 feet, and crest thickness of 80 feet. The total volume of the dam will be approximately 3.5 million cubic yards. The replacement dam will restore the original reservoir capacity of 96,850 acre-feet, or 31 billion gallons of water.

The Calaveras Dam Replacement Project is the largest among the 81 projects of our $4.6 billion Water System Improvement Program. Calaveras Reservoir is the Hetch Hetchy Regional Water System’s largest Bay Area reservoir, and when full represents more than half of the water storage outside of the Sierra Nevada.  


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Last updated: 7/27/2018 9:04:25 AM