Friday, July 10, 2015

One huge pipe at Calaveras Dam

As we busily work towards construction of a replacement Calaveras Dam, there are many fundamental issues we have to address. For example, given that the existing Calaveras Dam will be left in place when we are done, how will we be able to transport water out of the reservoir when the new dam is built?

Answer: We are building a large pipe (more than 7 feet in diameter) that will be completely buried in the new dam that connects directly to the outlet structure already in place in the existing dam.
This pipe will transport our drinking water supply from the Calaveras Reservoir to the Sunol Valley Water Treatment Plant and then on to our 2.6 million Bay Area customers when supplies are needed.
To date, our crews have installed 500 feet of the new steel pipe, welded  the joints, and started building the formwork for reinforced concrete encasement  around the entire pipeline to protect it. The pipeline and encasement  has been designed to withstand the force of being buried under 180 feet of earth embankment as well as the force of any seismic activity from the nearby Calaveras Fault. The team plans to connect the new 78 inch pipe to the existing pipes within the existing dam in Fall 2016. 

Seems a shame to put all this work into something that will be completely buried under more than 3.5 million cubic yards of earth and rock. But, thanks to these careful efforts, customers will be able to drink Calaveras Reservoir water, even after an earthquake.
The new pipe is shown here in orange on the layout, connecting to existing pipes in green.  The old pipeline in black is being abandoned to excavate the foundation for the new dam.