Waste Retrieval Operations Resume In Eleventh Single-Shell Tank at Hanford
Washington River Protection Solutions (WRPS) has resumed removal and transfer of waste from another of Hanford’s aging single-shell underground waste storage tanks. Waste retrieval from tank C-110 halted in September 2008 to allow for modifications within and to the double-shell waste receiving/storage tank AN-106. Retrieval is restarting approximately six months ahead of schedule. This is the first waste retrieval campaign since WRPS assumed responsibility for the Hanford Tank Operations Contract on Oct. 1, 2008.
“Everyone involved in this project did an outstanding job preparing for it and are committed to the safe and efficient removal of the waste from this tank,” said Mark Lindholm, WRPS single-shell tanks retrieval and closure manager.
Tank C-110 is one of 16 tanks located in C Farm in the 200 East Area near the center of the 586- square-mile Hanford Site. It is a 530,000 gallon tank, built in 1946, and currently holds approximately 126,000 gallons of sludge and other radioactive and chemical waste materials.
Waste from C-110 is being transferred to storage in tank AN-106, a newer and safer double-shell tank. The waste is being moved through temporary, above-ground hose-in-hose transfer lines to the double-shell tank approximately 900 feet away. The above-ground transfer lines meet environmental regulations and avoid the high cost of installing permanent infrastructure.
Retrieval of waste from C-110 is expected to take approximately four months.
Retrieval resumed earlier than originally planned thanks to the innovative efforts of WRPS engineers. Sludges were building up on the bottom of AN-106 and threatening the ability of the pump to re-circulate liquids used in emptying C-110. A two-piece collar was devised to raise the pump above the solid material, which avoided the cost and time involved to replace it.
Retrieval is being conducted with a number of improvements intended to enhance safety and environmental protection. Changes include the installation of improved methods to detect small waste leaks along the waste retrieval transfer route. This includes not only detection but also being able to visually verify the post-leak conditions prior to sending people into the area.
Tank C-110 is the eleventh single-shell tank at Hanford to undergo retrieval, which is being accomplished using a technique known as modified sluicing. This technique uses high-pressure nozzles to spray the waste with liquid to dissolve it or otherwise break it up and move it to a pump for removal.
“This is a well-proven technique to retrieve waste from these tanks. Everything we do is focused on worker safety and protection of the environment and this job is no exception,” said Bill Johnson, WRPS president and project manager.
WRPS, a company owned by URS Corporation and EnergySolutions, is a prime contractor to the U.S. Department of Energy’s Office of River Protection and is responsible for reducing the risk posed by the waste stored in Hanford’s aging underground tanks. The waste is contained in 149 single-shell tanks, many of which date back to the beginning of the Hanford Site during World War II. There are also 28 newer, safer double-shell tanks.
“Removing the waste from the single-shell tanks and upgrading the aging infrastructure in the tank farms is a top priority for the Department of Energy, a necessary step to protect the Columbia River, and key to providing tank waste feed to the Hanford vitrification plant in 2019,” said Office of River Protection Manager Shirley J. Olinger. “In preparing to resume this important work at Hanford, our team demonstrated a commitment to safety, efficiency, innovation and cost effectiveness.”
To date seven single-shell tanks have been emptied. The Washington State Department of Ecology has determined that six meet the retrieval criteria established in the Tri-Party Agreement which governs Hanford cleanup. The other tank is under review. Waste retrieval operations have begun in three other single-shell tanks in addition to C-110.
