Tuesday, July 10, 2018

First Structures Completed at Naval Ordnance Plant in Pocatello [otd 07/10]

On July 10, 1943 workers completed construction of the first usable structures for the Naval Ordnance Plant (NOP) about three miles north of Pocatello, Idaho. The Navy had authorized the Plant in the spring of the previous year. With more facilities completed later in the year, officials commissioned the NOP in early August, 1943.

Early in World War II, planners had to consider the possibility of attacks on the West Coast when they selected a site to refurbish big naval guns. Pocatello offered the proper transport connections to Coastal bases. Not only was it a major railroad junction, but a segment of transcontinental highway ran through the town. And, off to the northwest, the region offered plenty of open space.

Refurbished battleship gun.
Idaho State University Special Collections.
The most impressive structure at the NOP was the big gun shop. It was 840 feet long, 352 feet wide, and over seven stories tall. Inside, skilled mechanics and machinists could reline and refurbish the very largest battleship guns in the U. S. Navy. Repeated firing wears out the bore of any artillery piece. In particular, distortion of the rifling – the grooves that force shells to spin – severely degrades the gun’s accuracy. Only a specially-design facility, with massive tools and equipment, could handle the huge naval cannon.

Later they added three giant storage buildings – 605 feet long by 352 feet wide – where guns could be mounted and the mounts could be exercised. Besides these out-sized facilities, the site included smaller shops and storerooms, plus quarters for civilian and military personnel. In all, the station encompassed fifty buildings, most of them of permanent construction.

Refurbished guns had to be tested before they were shipped back to the fleet for re-installation. To provide a test range, the Navy commissioned a second site, located 50-60 miles northwest of Pocatello on what was generally called "the Arco desert." Except for three large, roughly cone-shaped buttes, that area is a mix a level plains and low, rolling hills.

On November 20, 1943, the Navy’s first tests were run on some small-caliber guns that had been refurbished. The commandant, Captain Walter E. Brown, told reporters that repairs on big battleship guns would begin “soon.” Captain Brown received an armed forces Legion of Merit award for his work in getting the NOP operational.

The test site eventually contained 27 buildings, including powder magazines, warehouses, a variety of shops, an administration building, and quarters for the operating personnel. Ordnance operators first did short-range proof tests, using a protective blockhouse and large reinforced-concrete targets. They also performed tests of the mounted guns, firing them into a vast cleared area to the north of the command complex.

After the War, the Ordnance Plant saw less and less activity, with a commensurate reduction in the civilian work force. The Pocatello Plant was decommissioned and sold in the mid-Fifties.

Officials "re-purposed" the remote test range in 1949, transferring ownership of the facilities to the Atomic Energy Commission, which called it the National Reactor Testing Station.
Test Shot Toward Big Southern Butte. U.S. Navy photo.

Still, during the Vietnam War the Navy again used the site for test-firing 16-inch battleship guns. By then, the northern range contained many new facilities so test operators fired the guns into the side of Big Southern Butte.

After numerous transformations in mission, the former test area functions today under the U.S. Department of Energy as part of the Idaho National Laboratory.
References: “Naval Ordnance Plant, Pocatello, Idaho,” Idaho Digital Resources, Idaho Commission for Libraries.
"Pocatello, Idaho," Building the Navy's Bases in World War II, U.S. Government Printing Office, Washington, D.C. (1947).
Susan M. Stacy, Proving the Principle, DOE/ID-10799 (2000).


  1. Very interesting.

  2. The last time I was in Pocatello it was to repair that very crane
    Those buildings are full of Judson Pacific, Shaw Box and General Electric cranes ranging in capacity from 5 ton to one 100 ton.