The Rocky Mountain Arsenal (RMA) (Operable Unit 16) comprises part of the 17,000-acre RMA site, which is a former U.S. Army chemical warfare and incendiary munitions manufacturing and assembly plant in Adams Count, Colorado. From the 1950s until late 1969, the U.S. Army used the RMA facility to produce the nerve agent GB (isopropyl methyl-phosphonoflu oridate). From 1947 to 1982, private industries leased major portions of the plant facilities to manufacture various insecticides and herbicides. Since 1970, facility operations primarily have involved the destruction of chemical warfare materials. Thirteen Interim Response Actions (IRAs) were determined necessary prior to implementing the final On-Post Record of Decision (ROD). Operable Unit 16 (M-1 Settling Basins area) is one of several areas being addressed as part of the Other Contamination Sources IRA. The ROD addresses interim remediation of source areas and management of contaminant migration. Th e primary contaminants of concern affecting the soil, sludge, and ground water are organics including pesticides, and metals including arsenic.

"02/26/90." "PB91-921484." "EPA/ROD-R08-90-036." "Office of Emergency and Remedial Response."