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EM deactivates COLEX equipment, advances mercury cleanup at Y-12
October 20, 2021

em deactivates colex equipment
Oak Ridge workers remove mercury and mercury-contaminated solids from process pipes in the column exchange, or COLEX, equipment at the Alpha-4 facility at the Y-12 National Security Complex. Image by UCOR

OAK RIDGE, TN – Crews are nearly finished deactivating the second of three collections of old, mercury-contaminated equipment surrounding the Alpha-4 facility at the Y-12 National Security Complex at Oak Ridge.

The project addresses potential environmental risks and moves EM a step closer to preparing one of Y-12’s largest high-risk contaminated facilities for demolition.

The column exchange, or COLEX, structures are connected to the four-story 500,000-square-foot Alpha-4 building, which was used for uranium separation from 1944 to 1945. Workers finished installing the COLEX equipment in 1955 for lithium separation, a process requiring large amounts of mercury. A significant amount of the mercury was lost into the equipment, buildings, and surrounding soils, and its cleanup is one of EM’s top priorities.

em deactivates colex equipment
A view of the deteriorated East Column Exchange (COLEX) structures, which were installed in the 1950s and operated until the 1960s. Image by UCOR

In 2018, cleanup contractor UCOR demolished the COLEX equipment on the west end of the building after retrieving 4.6 tons of mercury. The effort prevented a possible significant release of mercury into the surrounding environment.

In April, UCOR began deactivating the COLEX structures on the east end of the building. As crews close in on completing deactivation, expected in late November, they have so far captured another 1.25 tons of mercury from cleanup in those pipes and tanks.

“Much of our current East COLEX workforce was also involved in the deactivation and demolition of West COLEX, and they have done an excellent job using that previous experience to safely and effectively complete this deactivation effort,” noted Dan Macias, UCOR Oak Ridge Reservation environmental cleanup manager.

mercury treatment facility construction oak ridge
Construction is ongoing on the Mercury Treatment Facility at the Y-12 National Security Complex. The facility, set to be operational in 2025, opens the door for large-scale mercury cleanup at the site. Image by UCOR

To date, those crews have safely deactivated nearly 2,500 linear feet of process piping, abated 300 feet of asbestos, and removed all universal waste from East COLEX. The final portion of the COLEX equipment, located on the south side of Alpha-4, will be addressed in future years.

EM is also advancing construction on the Mercury Treatment Facility, the linchpin for EM’s cleanup strategy at Y-12 that enables large-scale mercury cleanup. It will prevent potential mercury releases into a nearby creek and allow EM to demolish massive mercury-contaminated buildings and address sources or mercury in the soil beneath them.

The facility, scheduled to begin operating in 2025, will treat up to 3,000 gallons of water per minute.

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