Abstract:
The U.S. Department of Energy (DOE) Hanford Site had a multi-decade career of supporting America’ s defense system during World War II and the Cold War. A multi-reactor site, DOE Hanford produced plutonium for atomic weapons as well as steam for generating electricity. In addition, a network of non-nuclear facilities was built and utilized to support the research and development process, like 324 Building. Due to the extremely inefficient process of making plutonium, massive amounts of liquid and solid byproduct were generated and ultimately stored on site. In 1989, after closing its doors to plutonium production, the DOE, Environmental Protection Agency (EPA), and Washington State Department of Ecology took on a challenging, legally binding accord to clean up the Hanford Site.
As part of the final clean-up project within the 300 Area, Nicholson was contracted to design and construct an underpinning micropile system to support the excavation efforts directly underneath the 324 Building “ B-Cell” structure to facilitate the complete removal of the contaminated soils directly beneath the structure. The work was completed in complex and challenging conditions that required an airtight drilling system, two layers of clothing, a hood with a Powered Air Purifying Respirator, the use of long reach tools, and continuous radiological monitoring.
This case study will address the design, construction, and challenges encountered with underpinning a structure within a highly sensitive category II nuclear environment.