Friday, September 7, 2012

Digging and Trenching

What is a concrete cut-off trench?
We just keep on digging out here at the Calaveras Dam Replacement Project site.  After excavating our first million cubic yards of materials in July, we have now completed our work on the first portion of the concrete cut-off trench. 

Why is it necessary?
The new Calaveras Dam will be an earth and rock fill dam, which naturally leaks water.  The concrete cut-off trench is an underground cement barrier located directly beneath the dam’s foundation. Groundwater will seep underneath the dam and the concrete cut-off trench will help slow the water flow to maintain the stability of the dam foundation.

How big is it?
Our workers excavated the trench and then filled it with approximately 300 yards of concrete.  The 30-inch wide trench is ten feet deep. When it’s finished it will be approximately 860 feet long. 

What’s next for the control of groundwater leakage?
We will continue work on the cut-off trench and install the grout curtain… and THAT we will share more with you later…



Calaveras Dam workers excavating with a trencher


View of Concrete-cut off trench work

For more project info, contact us at our 24 hour answer line at (866) 973-1476 or email mle@sfwater.org


 

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