Shasta hanger rod emergency installation

The temperature control device (TCD) is a steel structure consisting of a shutter structure and low level intake structure that are attached to the upstream face of Shasta Dam. The device encloses all five existing power penstock intakes and permits selective level withdrawal of reservoir water. High level withdrawal is controlled by the 250 ft-wide by 300 ft-high shutter structure. Construction of the TCD started in December 1994 and was substantially complete in December 1996.

A special climb inspection was performed March 6-8, 2023. Following the climb inspection, engineering analysis was completed on the hanger rod group located at the right side, downstream corner of Shutter No. 3. The inspection and analysis have confirmed that the Left Side Upstream (LS-US) hanger rod assembly no longer has the ability to provide structural support. With the loss of the LS-US hanger rod assembly, the entire hanger rod group at the right side, downstream corner of Shutter No. 3 is at risk of failure. These hanger rod assemblies are considered critical structural components because the loss of one of these corner hanger rod groups would likely lead to the failure of Shutter No. 3, and adjacent Shutter Nos 2 and 4. Awarded contract 140R2024C0004 to SHIMMICK CONSTRUCTION COMPANY, INC. for 323000 on 2023-11-15.