The Corps of Engineers estimates it could cost more than $4 million to replace equipment damaged in an electrical fire at its 100-MW Detroit Dam powerhouse on Oregon’s North Santiam River.
The Corps said it determined the cause of the fire to be a phase-to-phase arcing event that occurred in Unit 2 bus work, ancillary equipment used for the electrical connection from the generator to the step-up-transformer. An arcing fault is a high power discharge of electricity between two or more conductors.
No injuries were reported in the June 19 fire, which broke out on the lower level of the powerhouse. (HNN 6/22/07) While neither of the project’s two turbine-generators was damaged, both will remain off line indefinitely. Unit 1 already was off-line for maintenance at the time of the fire, the Corps said.
The Corps also shut down the 20-MW Big Cliff powerhouse, on the North Santiam River about three miles downstream. While Big Cliff was not damaged in the fire, its systems are connected to the Detroit powerhouse, which in turn is connected to a Bonneville Power Administration substation.
Damaged components had been earmarked for replacement
The Corps had been preparing to replace a number of Detroit’s components that subsequently were damaged in the fire. Erik Petersen, operations manager for the Corps’ Willamette Valley projects, said the Corps would solicit proposals to replace damaged components. The solicitation will be posted on the Portland District Internet site, www.nwp.usace.army.mil, in July, he added.
During the outage, water typically released through turbines in both powerhouses is being released over spillways to maintain river flow and to provide for fish listed as threatened or endangered under the Endangered Species Act. The Corps said cleanup efforts and the shutdown of generation would not affect the release of water to support fish and water quality. It said it would maintain current flow requirements through July 15, when it will reduce spill from both reservoirs.
Detroit and Big Cliff dams are among 13 multi-purpose dams operated by the Corps in the Willamette Valley. Detroit’s 463-foot-tall, 1,523-foot-long concrete gravity structure stores water for generation, flood control, irrigation, recreation, navigation, and downstream water quality improvement.