618-10 Burial Ground | ARRA

The 618-10 Burial Ground is considered the most complex Washington Closure has addressed to date. From 1954 to 1963, Hanford workers dumped highly radioactive waste into 94 vertical pipes and 23 waste trenches. Vertical pipe units, or VPUs, are five bottomless 55-gallon drums welded together end to end and buried vertically.

An extensive search of Hanford records yielded valuable information about burial ground contents. However, more information is needed before workers can safely clean up the site. Because of the potential risks and challenges, Washington Closure is taking an extremely cautious approach to clean up the 618-10 Burial Ground.

In late 2009, Washington Closure began nonintrusive characterization activities. Washington Closure subcontractor North Wind Inc. installed four narrow steel cylinders called cone penetrometers around each VPU and 100 cone penetrometers in selected trenches. A multi-detector probe is then inserted into the cone penetrometers to measure radiation sources.