Spillways are important safety features on any dam. They allow for the safe discharge of high water in a reservoir around a dam. And the new spillway at the Calaveras Dam Replacement Project is no different.
Work began on our spillway in March 2014. A total of 40,000 cubic yards of concrete, equivalent to one football field filled six feet deep, will be used to build the structure. All of the concrete is being supplied by our on-site concrete batch plant. The concrete is placed into the spillway in sections, or slabs. This spillway requires a total of 170 slabs, and we only have 18 more to go.
The spillway chute is 60 feet wide, equivalent to a five lanes of a highway. The slabs are strengthened with reinforcing steel bars and the entire structure is anchored to the bedrock to resist movement during an earthquake.
The quality of the concrete used in the structure is key. It has to be kept at a cool temperature while it cures in order to prevent cracking. Sunol Valley in summer is anything but cool. That means our crews often begin cement pours at 2 o'clock in the early morning, the coolest time of the day.
The spillway is expected to be completed later this year. This will be a major milestone for the project to complete this important feature of the dam.