Glendale Water & Power (GWP), Glendale, CA, has started repairs of a transmission line damaged during a severe lightning storm in 2005. Scheduled to be completed by November, the project to restore the transmission line that provides the back-up delivery of power to northern Glendale will consist of replacing the wires and reinforcing the footings of 14 transmission towers in the Verdugo Mountains.
The transmission line, which stretches over three miles in the Verdugo Mountains starting above Brand Park and ending in Montrose near Crescenta Valley Park, is supported by 14 electrical towers erected in 1955. Through the years, rain, water run-off, and dying vegetation have caused the soil underneath each of the towers’ four footings to erode, potentially making the towers unstable. The foundation piers need to be repaired to ensure that they are stable to hold the weight of both the towers and the wires that transmit electric power.
To reinforce the footings, GWP will replace the equivalent weight of soil that has eroded naturally, by installing wire cages with rocks and soil at each footing. This method has been used by the Army Corps of Engineers and other agencies to prevent erosion on hillsides. GWP has contracted with Henkels & McCoy to make the needed repairs and upgrades. The towers will also be re-painted and the existing 3.3 miles of transmission wires will be replaced.
GWP is also taking this opportunity to upgrade the transmission line to transmit at 69 kV instead of 34.5 kV. The upgrade will utilize ACSS conductor for the first time on the GWP system. This conductor was chosen to allow for the future installation of fiber optic cable on the same structures without adversely affecting structural integrity. This upgrade will increase the capacity of the line to improve the reliability of the electric service. The upgraded line will enable GWP to provide the capacity needed to support the electric load when other transmission lines that connect Montrose, Western, Bel-Aire and Glorietta substations become unavailable due to unforeseen changes. Such an upgrade will minimize the possibility of long outages.
“The upgrading of the line to a 69 kV system will increase capacity of the line by two and-a-half times, improving our reliability”, stated Ramon Abueg, Electrical Services Administrator. “This transmission line allows GWP’s electric system to provide redundant transmission service to the northern Glendale service area.”
Due to terrain which is inaccessible by land vehicles, GWP will be using helicopters to access the towers to deliver the footing material and string the new wires. The project will be partially funded by the Federal Emergency Management Agency, since this project was necessitated by the disastrous storm experienced in January 2005.