Friday, March 28, 2014

The Last Butterfly Valve for New Irvington Tunnel

You know you’re making progress on construction when you start celebrating your ‘lasts.’ Last excavation to be completed. Check!  Last steel liner inserted into the tunnel. Check! Now we have another: the last valve to be installed underground.

And not just ANY valve. This is a valve that is 8 feet in diameter that will eventually divert water from the existing piping connections into the New Irvington Tunnel.  This Butterfly Valve regulates flow within the pipe with a rotating a disc within the pipe. When closed, the disc, or butterfly, completely blocks flow.  When open , as seen in this sample of a butterfly valve from a dam in Japan, the disc rotates one quarter to allow flow to pass by.

And operating this valve is no easy task. If you were to manually crank it closed (or ‘actuate it’, as our operators say), you’d need a whopping 400 revolutions.  Our operators use electric actuators for this very reason, and will be able to operate this valve remotely.

We hope to actuate this valve to bring the New Irvington Tunnel into service this Fall!

New Irvington Team installs final valve

Sample Butterfly Valve
Photo courtesy of Wikimedia Commons

Friday, March 14, 2014

Calaveras Dam building a new and improved Spillway

Things sure look much different than it did in the early 1900s when the workers at the Calaveras Dam site were building the original spillway for the existing Calaveras Dam.  Today, we are building a new spillway over twice the size of the original.

Calaveras Dam workers rebuilding the spillway in 1933

Calaveras Dam workers today working on the foundation of
the upper portion of the new spillway

What’s the Spillway for?
A spillway is a structure used to control the release of flows from a dam into a downstream area. Spillways release overflow of water or floods so that the water does not overtop and damage the dam. When complete, the new spillway for the replacement dam will be approximately 1,550 feet in length and will be constructed using 40,000 cubic yards of concrete. Much work still lies ahead, but we are well on our way to rebuilding a critical feature of the replacement Calaveras Dam.