Concrete and Lead for Stanford
The builders had to use larger-than-normal cranes because of limited access to the new building's perimeter. Marcus Staniford, project executive for Rudolph and Sletten explains: "to accommodate installation of precast concrete panels on the building skin, we had to utilize a crane that could reach from one side of the building to the other, since we had limited or no access for a crane on the north, east, or south sides of the structure."
Building the Vaults
One of the biggest challenges was installing the seven linear accelerator vaults. Radiation shielding is frequently done with massive concrete, but because of limited space, a combination of concrete and lead was used instead.
Rudolph and Sletten subcontracted the installation of 1.6 million pounds (726,000 kilograms) of lead bricks on the walls, ceilings, and decks above the vaults to act as radiation shields. Lead-lined sheetrock and plywood were also installed throughout the basement and ground levels.
A major concern was worker and occupant safety during the lead cutting and installation. The general contractor provided special training and support to protect against lead exposure. Construction workers were monitored to ensure that they were wearing their respirators correctly and operating other protective equipment safely.
The workers cut lead inside a specially constructed booth equipped with high-efficiency particulate absolute (HEPA) filters and continuous exhaust to prevent lead particles from escaping to the ambient air. Rudolph and Sletten monitored the air continuously, both inside and outside the linear accelerator rooms, to make sure particulate levels were maintained within allowable limits.
The eight-inch (20-centimeter) lead shielding for the vaults was supplemented by concrete walls nearly five feet (1.5 meters) thick plus ten feet (three meters) of soil on the building perimeter. The resulting structure was much heavier than for conventional construction materials and methods. High gravity and lateral loads called for an unusual foundation system, including spread footings, mat slabs, and grade beams.
Construction was made still more complex by the installation of an on-site thermal fluid steam generation system. The self-contained system provides steam for heating hot water to support the building's nearly 300 supply-air variable-air-volume (VAV) boxes. It also delivers steam to the air-handler units for humidification and to the sterile-process area for sterilizing equipment.
The $85 million Center for Cancer Treatment and Prevention will bring under one roof all of Stanford University's resources for diagnosing and treating cancer, thereby enhancing patient care and improving access and convenience for patients and physicians. The center is scheduled to open in early 2004.
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