ABSTRACT
Subsurface soil and water contamination is a result of chemicals and other waste products that are introduced into the environment through improper disposal, accidental spills, and industrial and agricultural activities. The risk to human health is associated with the chemical dissolved in groundwater appearing at receptors such as drinking water wells or streams. The chemical may enter the subsurface directly dissolved in water or as a separate phase. An engineering classification system presented by La Grega et al. (1994) grouped hazardous waste that has the potential to contaminate soil and groundwater under six broad groups: inorganic aqueous waste, organic aqueous waste, organic liquids, oils, inorganic sludges/solids, and organic sludges/solids. Pathogens and nuclear wastes also act as sources of groundwater contamination (Kreider et al. 1998). As these chemicals are fully or partially soluble in water, they will eventually enter the saturated zone of the aquifers as contaminants that are hazardous to humans and ecological life.
