Fort Riley is a 152 square-mile US Army base located in Riley and Geary counties in north central Kansas. Established in 1853, it has been a major fort since the Civil War, with diverse operations including seven landfills, numerous motor pools, burn and firefighting pit areas, hospitals, pesticide and mixing areas, dry cleaners and shops. The installation is located along the north bank of the Kansas and Republican Rivers and between two major water reservoirs, Tuttle Creek Lake and Milford Lake. Groundwater contamination as a result of past and present operations is one of the most serious problems at this site. Others include pesticide residues in soils as well as various solvents that were used during fire training exercises. (13, 14, 15)

Investigations into the nature and extent of contamination at Fort Riley began in 1992, when vinyl chloride and other volatile organic compounds (VOCs) were found in shallow monitoring wells near the Camp Funston Landfill. Also found during these investigations was tetrachloroethylene (PCE) in groundwater approximately 3/4 mile down gradient from the water supply wells. Other areas found to have contaminations were the Dry Cleaning Facilities, Pesticide Storage Area, Building 354, Marshall Army Airfield Former Fire Training Area (FFTA) and at a number of other potential subsites. Contaminants found onsite included mercury, lead, waste oils and degreasing solvents. (EPA) Lead contamination will be discussed on the Cherokee County site page and other VOCs will be discussed on the 29th and Mead site page. (13, 14, 15)

Tetrachloroethylene, also known as PCE, is a carbon-carbon double bond with four attached chlorine atoms. PCE is not a naturally occuring chemical, instead it is commercially synthesized for use in dry cleaning facilities and as a metal-degreaser. A nonflammable liquid at room temperature with a sweet, sharp odor, PCE is insoluble in water. Volatilization to the air is the fate of most PCE that gets into water of soil. That which does not volatilize from the soil or is found in groundwater can be broken down by microbes, although oxygen levels are a limiting factor in this process. Once volatilized to the air, UV light or other chemicals, as well as being brought back to the surface through rainfall can cause the removal of PCE from the atmosphere. It has been determined that PCE is a possible human carcinogen, having been shown to cause liver tumors in mice and kidney tumors in male rats. (19, 20, 21)

Vinyl chloride, a colorless, flammable gas with a mild sweet odor, is manufactured through the halogenation of ethylene. It can also be a product of the breakdown of other substances such as tetrachloroethylene, trichloroethane and trichloroethylene, such as when they enter groundwater. Slightly soluble in water, vinyl chloride will transfer to the vapor phase easily if found in liquid form. Gaseous vinyl chloride in soils can also evaporate if it is near the soil surface. Once in the air, vinyl chloride will degrade into other substances, some of which can also be harmful, within a few days. Dizziness and drowsiness are the effects of breathing in high levels of vinyl chloride. Very high levels of vinyl chloride will cause one to pass out if breathed in and extremely high levels can cause death. Vinyl chloride has been determined to be a known carcinogen. (19, 20, 21)

A naturally occuring metal, mercury occurs primarily as organic mercury in soil and sediments and as an inorganic salt in water. In its metallic form mercury will evaporate easily. Methylmercury is the most common of the organic mercury compounds and is produced by microbes in soil and water. The most dangerous form of mercury is that of metallic mercury and methylmercury vapors as they can reach the brain when inhaled through respiration. Metallic, inorganic and organic mercury can cause permanent brain damage, kidney damage and damage developing fetuses if high levels of exposure occur. As well, methylmercury and mercuric chloride has been deemed possible human carcinogens.(19, 20)

The cleaning approach varied according to site and contaminant. At the landfill a rock revetment was built along the Kansas River to protect the water in the river from the contaminated soil. The soil cover over the landfill was improved as well. Contaminated soils were excavated and disposed of at the pesticide storage site. At other sites lead contaminated soils were excavated, stabilized and disposed of off-site. New wells have been constructed away from the polluted site in another, unpolluted aquifer. (13, 14, 15)