1942 to 1946 The construction of Rocky Mountain Arsenal (RMA) (encompasses 27 square miles) began. The Army was the sole user of the South Plants manufacturing complex. At various times during this period, the Army manufactured and/or filled munitions with chemical agents and chemical feedstock for chemical agents.

After WWII The Army did not manufacture chemical agents in the South Plants complex.

After WWII Most buildings in the South Plants complex were placed on standby status for military activities while portions of the manufacturing complex were leased to private industry for the production of commercial products.

1946 to 1982 Records were located for nine companies that conducted manufacturing or processing operations in the South Plants. Manufacturing activities ceased in 1982. The two major lessees of facilities in the South Plants were Julius Hyman and Company (1947 to 1952) and Shell Oil Company (1952 to the present).

1956 and 1966 The Army used buildings that it had not leased to others in the South Plants Area complex to demilitarize or recondition chemical agent munitions.

1971 to 1974 The Army continued demilitarizing chemical agent munitions at the South Plants facilities again.

1976 The Army transferred chemical agent from existing storage containers to modified containers to comply with Department of Transportation (DOT) requirements.

1961 to 1982 The Army operated, in conjunction with the Air Force, a chemical agent blending and storage facility in the eastern portion of the South Plants complex.

1951 to 1953 The North Plant Area (NPA) was constructed.

1953 to 1970 The NPA was used by the Army to manufacture and fill chemical agent munitions. The majority of the NPA was comprised of the Production Site and Fill Site.

1956 to 1958 The Toxic Storage Yard was constructed. This storage yard became the main storage area for chemical agent, byproducts and materiel after 1969 and was used until the early 1980s when all chemical weapons stockpiles were removed from RMA.

Beginning in the 1970s, a series of Interim Response Actions (IRA) were implemented to protect offsite human health and environment from RMA pollution.

1989 The U.S. Army and Shell entered into the RMA Federal Facility Agreement (FFA) that included continued remediation activities.

A 155 mm projectile, M110, was found at RMA.

11 June 1996 The Army, EPA, and State of Colorado signed the On-Post Record of Decision (ROD), which provides for cleanup actions to be accomplished at the site.

In 2000, six M139 GB Bomblets were discovered at RMA and subsequently destroyed by the EDS from January to February 2000.

In 2001, four M139 GB Bomblets were disvered at RMA and subsequently destroyed by the EDS in July 2001.