Grand Junction, Colorado: The Manhattan Project's Secret Uranium Refinery

Second Lieutenant Philip C. Leahy. U.S. Department of Energy.

Why Grand Junction

More than 80 years ago, the United States set out to build an atomic bomb and needed uranium, a rare ingredient. The Manhattan Engineer District — running the Manhattan Project, the secret program that produced the first atomic weapons in World War II — got most of its raw uranium from Canada and Africa. Relying on them was risky, so the government wanted a domestic source.

Western Colorado and eastern Utah had the richest known uranium ore in the country. The government picked Grand Junction, Colorado, the area's largest town, as a uranium-processing site.

The lieutenant on the train

In 1943, Second Lieutenant Philip C. Leahy of the U.S. Army Corps of Engineers, a civil engineer by training, was working at the Manhattan Project's Metallurgical Laboratory in Illinois. There he met Lieutenant Colonel Thomas T. Crenshaw, who ran the project's uranium buying. Crenshaw told him to pack and catch a train to a new post — and Leahy didn't learn where until he stepped off: Grand Junction.

As head of the new Colorado Engineer Office, Leahy's job was to get as much uranium as possible from the Colorado Plateau. He set up an office downtown.

A refinery in a gravel pit

Leahy bought 55 acres (22.25 hectares) behind the town's municipal cemeteries — a former gravel pit — and workers quickly turned it into a uranium refinery, with a log cabin as its office. It suited a secret operation:

• a rail spur already ran in, so materials could be loaded and shipped out of public view;
• it was just outside city limits, with little passing traffic;
• the Gunnison River wrapped around it on three sides, supplying water for the refinery and keeping people out by land.

By 1946, the Colorado Plateau had produced more than 2.6 million pounds (1,179.34 metric tons) of uranium oxide, or "yellowcake" — about 14% of all the uranium the Manhattan Project obtained. The public knew little: news reports said the mill was making vanadium, a steel-hardening metal used in the war.

The refinery's log-cabin office in a historic photograph. U.S. Department of Energy.

The Atomic Legacy Cabin

Grand Junction's part in the Manhattan Project is no longer a secret.

• In 2001, the Department of Energy transferred the old refinery site to the Riverview Technology Corporation (RTC), a nonprofit the city and Mesa County created to grow the local economy and jobs. RTC then leased the cabin back to the department.
• Together they created the Atomic Legacy Cabin, a public interpretive center telling the story of uranium mining and milling on the Colorado Plateau through exhibits and interactive displays.
• The cabin and most of the refinery site are on the National Register of Historic Places, and are used for public programs and STEM education.

Further reading

• William L. Chenoweth, "Raw Materials Activities of the Manhattan Project on the Colorado Plateau," Nonrenewable Resources 6 (1), 1996.
• Gavin Hadden, ed., Manhattan District History, Book VII, Volume 1, U.S. Atomic Energy Commission, 1947.
• National Park Service, National Register of Historic Places registration form, 2016.

Sources

Based on "Grand Junction, CO," by Richie Ann Ashcraft and Malaika Michel-Fuller, contractors to the U.S. Department of Energy Office of Legacy Management, Manhattan Project National Historical Park; published by the National Park Service and in the public domain; rewritten in hubnx's own words. The photographs are the Department of Energy's.