Rocky Mountain Arsenal The Rocky Mountain Arsenal was a United States chemical weapons manufacturing center located in the Denver Metropolitan Area in Commerce City , Colorado . The site was operated by the United States Army throughout the later 20th century and was controversial among local residents until its closure in 1992 . Much of the site is now protected as the Rocky Mountain Arsenal National Wildlife Refuge . Site selection . The Arsenal ' s location was selected due to its relative distance from the coasts ( and presumably not likely to be attacked ) ; a sufficient labor force to work at the site ; weather that was conducive to outdoor work ; and the appropriate soil needed for the project . It was also helpful that the location was close to Stapleton airfield , a major transportation hub . In 1942 , the US Army acquired 19 , 915 acres ( 80 . 59 km² ) of land on which to manufacture weapons in support of World War II military activities at a cost of $ 62 , 415 , 000 . Additionally , some of this land was used for a prisoner of war camp ( for German combatant s ) and later transferred to the city of Denver as Stapleton Airport expanded . A lateral was built off the High Line Canal to supply water to the Arsenal . Manufacturing operations . Weapons manufactured at RMA included both conventional and chemical munitions , including white phosphorus ( M34 grenade ) , napalm , mustard gas , lewisite , and chlorine gas . RMA is also one of the few sites that had a stockpile of Sarin gas ( aka nerve agent GB ) , an organophosphorus compound , and one of the most toxic substances ever created in a lab . The manufacture of these weapons continued until 1969 . Rocket fuel to support Air Force operations was also manufactured and stored at RMA . Subsequently , through the 1970s until 1985 , RMA was used as a demilitarization site to destroy munitions and chemically related items . Coinciding with these activities , from 1946 to 1982 , the Army leased RMA facilities to private industries for the production of pesticide s . One of the major lessees , Shell Oil Company , along with Julius Hyman and Company and Colorado Fuel and Iron , had manufacturing and processing capabilities on RMA between 1952 and 1982 . The military reserved the right to oust these companies and restart chemical weapon production in the event of a national emergency . Deep injection well . RMA contained a deep injection well that was constructed in 1961 . It was drilled to a depth of 12 , 045 feet ( 3671 m ) . The well was cased and sealed to a depth of 11 , 975 feet ( 3650 m ) , with the remaining 70 feet ( 21 m ) left as an open hole for the injection of Basin F liquids . For testing purposes , the well was injected with approximately 568 , 000 US gallon s ( 2150 m³ ) of city water prior to injecting any waste . The injected fluids had very little potential for reaching the surface or usable groundwater supply since the injection point had 11 , 900 feet ( 3630 m ) of rock above it and was sealed at the opening . The Army discontinued use of the well in February 1966 because the fluid injection triggered a series of earthquakes in the area . The well remained unused until 1985 when the Army permanently sealed the disposal well . Environmental issues . In 1984 , the Army began a systematic investigation of site contamination in accordance with the Comprehensive Environmental Response , Compensation and Liability Act of 1980 ( CERCLA ) , commonly referred to as Superfund . In 1987 , the RMA was placed on the National Priorities List ( NPL ) of Superfund sites . As provided by CERCLA , a Remedial Investigation / Feasibility Study ( RI / FS ) was conducted to determine the extent of contamination . Since 1985 , the mission at RMA has been the remediation of the site . Contaminants . The primary contaminants include organochloride pesticides , organophosphate pesticides , carbamate insecticides , organic solvent s and feedstock chemicals used as raw products or intermediates in the manufacturing process ( e . g . , chlorinated benzenes ) , heavy metals , chemical warfare material and their related breakdown products and biological warfare agent such as TX . Additionally , ordnance ( including incendiary munitions ) was manufactured and tested , and asbestos and polychlorinated biphenyls ( PCBs ) were used at RMA . Today , it is considered a hazardous waste site according to the Colorado Department of Public and Environmental Health . Japanese involvement . The late Ban Shigeo , a technician at the Japanese Army ' s 9th Technical Research Institute , left a rare and valuable account of the activities of Noborito Research Institute which was published in Rikugun Noborito Kenkyujo no shinjitsu - The Truth About the Army Nororito Institute available only in the Japanese language . Of the Japanese Army ' s ten numbered institutes , only the 9th Army Technical Research Institute came under the covert operations section of the Army General Staff ' s Second Bureau ( Intelligence ) . On the sensitive issue of Japanese biological warfare , Ban did not shrink from including an account of his trip to Nanking in 1941 to participate in the testing of poisons on Chinese prisoners . One of his book ' s contributions is to further tie Noborito to the Japanese Army ' s infamous Unit 731 , which participated in biomedical research . When the war ended , the US Army quietly enlisted certain members of Noborito in its efforts against the communist camp in the early years of the Cold War . The author notes near the end of the book that Ban led the " chemical section " of a US clandestine unit hidden within Yokosuka naval base during the Korean War , and then worked on unspecified projects inside the United States from 1955 to 1959 , before returning to Japan to enter the private sector . Evidence that Japanese continued to assist the United States Chemical and Biological warfare program efforts continued after the Korean war into Vietnam includes a visit to Rocky Mountain Arsenal in September 1962 by Japanese delegation I - 63 . Among many other activities , from January 1962 - October 1969 , Rocky Mountain Arsenal “ grew , purified and biodemilitarized ” plant pathogen Wheat Stem Rust ( Agent TX ) , Puccinia graminis , var . tritici , for the Air Force biological anti - crop program . TX - treated grain was grown at the Arsenal from 1962 - 1968 in Sections 23 - 26 . Unprocessed TX was also transported from Beale AFB for purification , storage , and disposal . Trichothecenes Mycotoxin is a toxin that can be extracted from Wheat Stem Rust and Rice Blast and can kill or incapacitate depending on the concentration used . The “ red mold disease ” of wheat and barley in Japan is prevalent in the region that faces the Pacific Ocean . Toxic trichothecenes , including nivalenol , deoxynivalenol , and monoace tylnivalenol ( fusarenon - X ) from Fusarium nivale , can be isolated from moldy grains . In the suburbs of Tokyo , an illness similar to “ red mold disease ” was described in an outbreak of a food borne disease , as a result of the consumption of Fusarium - infected rice . Ingestion of moldy grains that are contaminated with trichothecenes has been associated with mycotoxicosis . Rocky Mountain Arsenal NWR Act . In 1986 it was discovered that the absence of human activity had made the area an involuntary park when a winter communal roost of bald eagles , then an endangered species , was discovered on site . The U . S . Fish and Wildlife Service soon realized that more than 330 species of wildlife inhabit the Arsenal including deer , coyotes , white pelican s and owl s . The Rocky Mountain Arsenal National Wildlife Refuge Act was passed in October 1992 and signed by then President George H . W . Bush . It stipulates that the majority of the site will become a National Wildlife Refuge under the jurisdiction of the Fish and Wildlife Service when the environmental restoration is completed . The Act also provides that to the extent possible , parts of the Arsenal are to be managed as a Refuge in the interim . Finally , the Act provides for the transfer of some Arsenal land for road expansion around the perimeter of the Arsenal and 915 acres ( 3 . 70 km² ) to be sold for development and annexation by Commerce City . Developments since 2004 . Although comprising 17 , 056 acres ( 69 . 02 km² ) at the beginning of remediation in 1997 , 5 , 976 acres ( 24 . 18 km² ) of the RMA have been determined to meet cleanup requirements and are no longer part of the National Priorities List . Of that , approximately 4 , 927 acres ( 19 . 94 km² ) were transferred by the Department of Army to the USFWS in April 2004 and another 917 acres ( 3 . 71 km² ) , located in the southwest corner of the site , were sold to Commerce City in June 2004 . Also , in 2004 , approximately 129 acres ( 0 . 52 km² ) , located at the boundaries , were transferred to local jurisdictions and to the U . S . Army Reserve Center for road improvement projects . An additional was transferred to the USFWS in October 2006 , making the Rocky Mountain Arsenal Wildlife Refuge one of the largest urban refuges in the United States . At that time the refuge comprised and is home to more than 330 species of animals . Implementation of the remedy for the estimated 11 , 080 acres ( 44 . 84 km² ) remaining is ongoing and is scheduled for completion in 2011 . As of September 2010 clean - up was considered as complete and the remaining portions of land were transferred over to the U . S . Fish and Wildlife Service bring the total to 15 , 000 acres . The two remaining sites on the property that are retained by the Army are the South Plants location due to historical use and the North Plant location which is now a landfill containing the remains of various buildings used in the North and South Plant locations . As of May 21 , 2011 the official Visitor Center was opened with an exhibit about the site ' s history ranging from the homesteading era to its current use as a National Wildlife Refuge ( http : / / www . fws . gov / rockymountainarsenal / ) . Public use . Congruent with the outline of the June 1996 USFWS Comprehensive Management Plan , RMA will be available for public use through both community outreach and educational programs ( as provided by the Visitor Access Plan and the USFWS ) . This public availability will be implemented while simultaneously supporting the remediation effort and the USFWS activities . Dick ' s Sporting Goods Park . In April 2007 Dick ' s Sporting Goods Park , a soccer - specific stadium , was opened on part of the former Rocky Mountain Arsenal land that was transferred to Commerce City . The new venue hosts the Colorado Rapids of Major League Soccer . Bison . A small herd of wild bison was introduced to the refuge in March 2007 as part of the USFWS Bison Project . The animals were transferred from the National Bison Range in Montana .