The Rocky Mountain Arsenal (RMA) is nearly 27 square miles, roughly the size of Manhattan. RMA is located at the western edge of the Colorado plains, near the foothills of the Rocky Mountains, ten miles northeast of downtown Denver, Colorado. The U.S. Army established the RMA in 1942 to produce incendiary munitions and chemical warfare agents such as mustard gas used in World War II. Following the war, and through the early 1980s, the Army continued to use these facilities. Private industry was also encouraged to lease facilities at RMA after the war to foster economic growth in the area, offset operational costs and maintain facilities for national security. Under the lease program, Julius Hyman and Company began producing pesticides in 1946. In 1952, Shell Chemical Company acquired Julius Hyman and Company and continued to produce agricultural pesticides onsite until 1982. These activities over time resulted in widespread and significant environmental contamination across the site.