The Hanford Engineering Works was conceived in June 1942 under the direction of Major General Leslie R. Groves, head of the famous Manhattan Project, to produce plutonium and other materials for use in the development of nuclear weapons. By December 1942, a decision was reached to proceed with the construction of three plants—two to be located at the Clinton Engineering Works in Tennessee and a third at the Hanford Engineering Works in Washington.

Hanford was established in the southeastern portion of Washington state between the Yakima Range and the Columbia River, about 15 mi (24 km) northwest of Pasco, Washington. The site occupies approximately 586 mi²(1,517 km²) of desert with the Columbia River flowing through its northern region. Once a linchpin of United States nuclear weapons production during the Cold War era, Hanford has now become the world's largest environmental cleanup project.

Hanford Engineering Works, known as HEW...