BURBANK, Wash. – As the U.S. Army Corps of Engineers team Ice Harbor Lock and Dam performs repairs of power transformer heat exchangers or “cooling units” that recently leaked oil into the river, the Corps is taking precautions to protect Endangered Species Act-listed fish. This effort is part of the Corps’ overall environmental stewardship efforts.
Generator main unit #3 had been out of service since Feb. 14, 2012, to repair its transformer cooling units. Prior to re-starting it Wednesday, March 14, in order to remove water in the turbine area, the Ice Harbor team was required by the federal Fish Passage Plan to “spin” or run water through the turbine because there likely would be fish remaining in the turbine’s draft tube. However, a small amount of "ISO 100 turbine oil" had likely accumulated in the turbine area, so the team created a plan to remove that oil without harming fish and simultaneously minimize the risk of oil leaking into the Snake River when the turbine was spun.
The plan was to first inject air into the unit prior to “spin” to help oil move to a high point in the turbine area, where oil could more easily be removed. Also, as the turbine was spun, the Ice Harbor team would position boats with oil-absorption booms below the dam to try and capture any oil that might leak to the river.
The team began implementing the plan on March 13 and completed it March 14. While some oil was captured from the turbine-area high point, a silver sheen was observed downstream, indicating some oil had entered the river. The Corps quickly responded to use absorption booms to capture as much of the spill as possible. An estimated 5 to 10 gallons of oil was released to the river during the operation.
Previously, oil cooling units had been traced as the likely source of an oil sheen observed by Corps staff and reported to state officials in December 2011 and January 2012. The transformers and cooling units are being repaired; part of the repair process is to replace older oil into the transformers and cooling units. During a Feb. 27 cooling unit oil-flushing operation, oil escaped from an open transfer connection, onto a concrete floor in the powerhouse and into a drain running to the powerhouse drainage sump. An estimated 44 gallons of oil leaked into the river at this time, and Corps clean-up efforts were made by crews from Ice Harbor and Lower Monumental Lock and Dam.
The Corps is fully cooperating with investigations of those earlier leaks by the EPA and Washington Department of Ecology.
Release no. 12-19