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Yuba Water Agency is one step closer to ramping up operations of its recently acquired Narrows 1 hydroelectric power generation facility after the agency’s maintenance and engineering crews replaced a leaky stand pipe, which is a crucial part of the system that moves water from Englebright Reservoir to the facility.
Upon taking ownership of the Narrows 1 facility, Yuba Water attempted to restore the power-generating unit, but discovered that the stand pipe was leaking. Crews then evaluated the pipe and noted pin-hole leaks throughout, indicating extensive damage.
The stand pipe is tied directly to the penstock, which is the main pipe that delivers water from the reservoir to the facility, so a failure of the thin-walled stand pipe could have resulted in an uncontrolled release of water from Englebright.
The project consisted of removing the old pipe and replacing it with seven new, separate pieces of pipe, which were bolted together to form one continuous pipe. While the concept of the project may seem relatively simple, the agency’s crews were forced to endure numerous obstacles that were thrown their way.
Because of the pipe’s location on a steep incline, the worksite was inaccessible by typical heavy-lift equipment such as cranes and forklifts. Additionally, the only way for crews to access the worksite was by a 200-foot-long single walking path or the small tram that leads into the hydropower facility.
Given the above constraints, the agency elected to use a helicopter to remove the old pipe in sections and fly each of the new pieces in.
Another key constraint that Yuba Water dealt with was that the project area is a known peregrine falcon nesting site. Because the species is fully protected in California, it required months of extensive observation to ensure that no falcons were, or would be, present while the replacement project was underway. If any had appeared, the project would have been called off and delayed.
The entire pipe was removed from the hill in approximately two hours. Once the removal was complete, crews stacked and bolted the new sections in place. The assembly portion of the project took approximately a day and a half to get all of the sections in and secure.
Now that the stand pipe has been replaced, the next step is to conduct testing.