Rocky Flats Plant - Building #991 (Plant D)/Building #991

Address: Rocky Flats Environmental Technology Site, Hwy. 93, Golden 80402

Designed and built by the Austin Co. of Cleveland, Ohio, in 1952, this 40,780 sq. ft. building housed the final assembly of weapons components, testing, and inspection. It is a rectangular concrete building set on a concrete foundation. Two wings extend from the east and west sides. The vaults are constructed of reinforced concrete up to 30" thick, and are completely underground. In 1952, vaults #998, #997, and #996 were constructed. Operations began in 1952 with the first production shipped in 1953. Vault #999 was constructed in 1956. It is the only building at the Rocky Flats Plant that is capable of handling off-site shipments of Special Nuclear Materials. In 1957, production began on the new Part IV weapons design, so the pit assembly was moved to Building #777 from this building. After 1957, Building #991 became used increasingly for shipping, receiving and storage.
Quad Map/Date: Louisville, 1965 (1979)
Sec/Town/Range: S10 & 11; T2S, R70W
Elevation: c. 6000
Source: Historic Building Inventory Record #5JF1014.42, 1995, Colorado Historical Society.

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