Vast Storage Bunkers for Military Ordnance

If you have driven on Interstate Highway 84 east from The Dalles to Hermiston you may have noticed a large series of bunkers north of the highway near Boardman. It might have created a curiosity as to what the bunkers were built for. In 1940 the U.S. Army identified over twenty thousand acres of barren land near the county line between Morrow and Umatilla counties that would be suitable as a site for a munitions and supply depot.

Construction of the depot was begun in January 1941. A primary civilian contractor was selected to do the construction. The site was chosen because it was safe from sea attacks and it was close to railroad lines and a port on the Columbia River. The mild climate, low humidity, and sparse population were also factors in the selection. At the peak of construction, seven thousand men worked three shifts a day building munitions storage bunkers, barracks, a headquarters, base housing units, warehouses, workshops, a fire station, and a railroad engine house.

The Umatilla Army Ordnance Depot was opened on October 14, 1941, when the depot was officially designated a military reservation. On October 27, the first shipment of twenty thousand bombs arrived by rail for storage. In late fall, the initial civilian contracts were completed, and the Army Corps of Engineers took over supervising various contractors as building continued at the depot. The total cost of construction was $35 million.

The bunkers were called igloos and were constructed in rows and igloo size varied from large (30 by 80 feet) to small (24 by 61 feet). Over 1000 igloos were constructed with ends and sides ten inches of reinforced concrete, covered with two feet of dirt. The concrete tops were constructed so that the force would be directed upward if an explosion occurred.

The Umatilla Army Ordnance Depot stored and supplied munitions to the army until the early 1990s. Between 1962 and 1969, chemical weapons were received and stored at the depot; and from 1996 to 2012, under the name Umatilla Chemical Agent Disposal Facility, the depot was the site of the destruction of those weapons. During incineration, 220,604 munitions and 3,720 tons of chemical weapons were safely destroyed. Incineration was completed in October 2011, the incineration plant was demolished, and the depot was closed on August 1, 2012. The total cost of the project is estimated at $2.7 billion. The igloos were determined to be too expensive to remove and will probably remain on the landscape.

Contributed by Steve Lent, Historian