The Dalles Dam transformer leak

Status updates

March 22, 2010

As of March 8, Ecology is no longer represented in Unified Command.  However, Ecology's Toxics Cleanup Program will be working closely with the Corps of Engineers on final remediation.  At this time, the oil is not migrating further and the grout curtain has been effective.  Recovery wells are in place to support further operations.

January 26, 2010

Oil spill recovery and cleanup continues at The Dalles Project transformer spill site.

The underflow dam has been completed and is effectively reducing oil seeping to the Columbia River. Sorbents in the sluiceway behind the underflow dam are collecting small amounts of oil. The area behind the hard boom at the outfall to the river appears clear.

Unified Command met on Monday, January 25, to assess cleanup progress and develop the Operational Period Plan for January 25 through February 10. This current plan directs several operations including:

• refinement of Mass Balance Data (amount of oil spilled, recovered, unrecovered),
• completing the removal of remaining petroleum contaminated soil,
• cleaning of contaminated scuppers in the sluiceway,
• exploratory drilling & monitoring wells, and
• periodic sampling.

January 6, 2010

Oil spill recovery continues at The Dalles Project transformer spill site.  

The underflow dam in the sluiceway is near completion and is already proving effective in collecting oil that is still seeping from the adjacent spill area.  The sorbents in the sluiceway continue to collect oil.  The hard boom at the sluiceway outfall is containing residual sheen.  While much of the contaminated soil has been removed from the site for disposal, further excavations may be necessary.  Sampling will continue as mass-balance numbers are being refined.

On Thursday, January 7, Unified Command will meet to evaluate progress on the cleanup and develop the next Operational Period Plan.  At that time Operations along with technical specialists from the Corps of Engineers, Ecology, and EPA will present plans for ongoing cleanup. These plans may include the installation of recovery wells, a controlled flushing program, or other oil recovery operations.  Unified Command will evaluate the proposals, select the best methods, and incorporate them in Thursday's Plan.   

The investigation continues into why the secondary containment surrounding the transformer failed.

December 29, 2009

Unified Command resumed activity on December 28 focused on source control and recovery of oil sheen on the water.  Oil has been contained to the immediate area of the ice and trash sluiceway with the placement of hard boom lined with adsorbent material to recover accumulated oil sheen.  Petroleum contaminated soil removal continues and the area of excavation has been expanded by removing additional blacktop surface.

An underflow dam is being constructed in the ice and trash sluiceway as an additional oil containment and recovery measure.  Additional measures will be evaluated to improve the gate seal on the sluiceway.

Unified command is evaluating long-term cleanup options for removing oil from impacted basalt and other areas which can’t be readily excavated.

Sampling and analysis is being conducted from potable water wells in the immediate area and from excavated areas to determine contaminated soil removal efficacy. 

An estimated 2,250 gallons is believed to have been released from the transformer.  Much of that has been recovered in the 120 cubic yards of excavated contaminated soil and oil-saturated adsorbents.  The full mass-balance of recovered oil has not yet been estimated.

The investigation continues into why the secondary containment surrounding the transformer failed.

December 24, 2009

PORTLAND, ORE. – U.S. Army Corps of Engineers, U.S. Environmental Protection Agency and Washington Department of Ecology emergency response teams continue containing and cleaning up about 3,250 gallons of light mineral-type oil that leaked from a spare transformer at The Dalles Lock and Dam on the Columbia River near The Dalles, Ore.

A small amount of oil has spilled into the Columbia River. Aircraft and boat crews are searching the river to determine if any oil has escaped the immediate area of the dam. So far, none has been detected. Environmental cleanup crews are also working to prevent oil that is leaking into the dam’s ice and trash sluiceway from reaching the Columbia River.

Crews are removing contaminated soil from around the containment facility where the spare transformers are stored. Crews are also conducting tests of the surrounding area to determine how far the oil may have spread underground, and developing long-term plans to detect and remove it.

An investigation is underway to determine why the oil containment systems surrounding the transformers failed.

The Corps, EPA and Ecology have formed a unified incident management team to oversee the containment and cleanup effort.

December 23, 2009

Corps, Ecology responding to the Dalles Dam Transformer Leak

PORTLAND, ORE. – U.S. Army Corps of Engineers, U.S. Environmental Protection Agency and Washington Department of Ecology emergency response teams are responding to an oil leak from a transformer at The Dalles Lock and Dam on the Columbia River near The Dalles, Ore.

Light mineral-type oil was discovered to have leaked from a spare three-phase transformer staged outside of the powerhouse on the lower deck of the dam at about 11 a.m. today.  The transformer has a capacity of 6,500 gallons of oil; about half has been recovered.  Approximately 3,250 gallons is believed to be in the ground near the transformer.  The oil does not contain PCBs.

Some of the uncontained oil traveled across the ground and entered the dam’s ice and trash sluiceway through drainage holes.  An unknown amount reached the river, creating a sheen near the sluiceway exit.  No oil has been detected further downstream.

Much of the uncontained oil has leached into the ground.  Responders are collaborating with the U.S. Environmental Protection Agency, Oregon Department of Environmental Quality, Washington Department of Ecology and other interested parties to develop a plan to contain and remove the remaining oil.

The cause of the spill was due to a valve failure on the spare transformer.