KAHLOTUS, Washington -- U.S. Army Corps of Engineers operations officials at Lower Monumental Lock and Dam investigated and confirmed a suspected oil leak in hydroelectric generator unit number 2, today.
A follow-up report confirming the suspected oil leak was sent to the Environmental Protection Agency - Region 10 and the Washington Dept. of Ecology.
Maintenance workers at the dam are preparing to remove remaining oil from the turbine hub today, preventing any additional unintended release of oil into the water. The unit will remain out of service until it can be un-watered to conduct repairs.
The suspected leak was first reported Thursday, Aug. 3, and the generator unit was shut down when maintenance workers detected a discrepancy in the mass balance of turbine oil at Lower Monumental Dam’s powerhouse. Corps staff investigated the suspected leak and were able to confirm that a slow leak had allowed oil to enter the water. An estimated 742 gallons of oil slowly leaked from the unit during about a seven-month-long period.
The Corps’ oil accountability program led to the decision to take unit 2 out of service while staff investigated to conclusively determine if there was an oil leak from the turbine runner into the water. However, all six units’ oil systems are interconnected, making it very difficult to quantify the amount of oil in an individual unit.
“Because unit 2 is the primary generator at LoMo, it is constantly in operation, a slow leak like that, releasing a very small volume of oil per hour, wouldn’t likely be very noticeable in the water during normal operations,” said Don Redman, the Corps’ Walla Walla District environmental compliance coordinator. “We take our responsibility seriously to maintain and operate these dams in an environmentally sound manner, adhering to all federal and state regulations. We always strive to prevent pollutants from entering the river and will be taking action to help prevent this from happening in the future at all of our facilities.”
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Release no. 17-087