Washington Closure Hanford is making preparations to start cleaning up the second of two high hazard burial grounds used to dispose of Hanford research waste near the Columbia River.
It has awarded a subcontract worth almost $4.3 million to Cheyenne Electric of Kennewick to install the infrastructure needed to retrieve the waste in the 618-11 Burial Ground. Retrieval already is underway at the 618-10 Burial Ground.
Full scale cleanup of 618-11 is expected to begin in mid-2013, using what workers are learning as they clean up 618-10. Both burial sites contain a mix of chemical and radioactive research waste from many projects.
Several years will be needed to compete cleanup of 618-11, said Rob Cantwell, director of field remediation for Washington Closure.
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The 618-11 Burial Ground is adjacent to the parking lot of Energy Northwest's Columbia Generating Station, the commercial nuclear power plant on leased Hanford land north of Richland.
From March 1962 through December 1967, the burial ground was used for waste from Hanford's 300 Area, just north of Richland, where research was conducted and fuel for Hanford reactors producing weapons plutonium was manufactured.
Already, surveying has been done to find the burial structures at 618-11. Ground penetrating radar was among the methods used to locate 50 vertical pipe units and four large caissons into which Hanford workers dumped waste materials.
The vertical pipe units typically were built by welding five bottomless 55-gallon drums end to end. The larger caissons are containers 8 feet in diameter and 10 feet long, and are built of corrugated metal pipe. They are buried about 15 feet below ground with slanted 3-foot pipes that waste was dropped down.
The burial ground also includes three trenches with sloped sides about 900 feet long. Washington Closure believes that low- to moderate-activity radioactive waste was disposed of in the trenches and moderate- to high-activity radioactive waste was disposed of in the vertical pipe units and caissons.
Washington Closure also has driven steel tubes into the soil near each vertical pipe unit at 618-11 to allow it to drop down instruments to take radiation readings.
Data collected was used to determine the possible contents of the waste disposed of there.
Existing waste disposal records, which date from before records were routinely computerized, are incomplete.
The next step will be installing the infrastructure that will be needed for cleanup of 618-11.
Cheyenne Electric, which was formed in 1996, will begin infrastructure work this spring and is expected to complete its work late this year.
It will install water lines and electricity and build roads, parking lots and an area to transfer containers of waste onto trucks.
Methods for retrieval of the vertical pipe units at both 618-10 and 618-11 have not been finalized.
At 618-10, which has 94 vertical pipe units and 12 waste trenches, work is further along.
Retrieval of waste began in the trenches this summer.
About 130 waste drums have been retrieved and are being processed and about 250 bottles, some with liquid, have been discovered, and work is ongoing to develop a system to efficiently process large numbers of bottles.