ABSTRACT:
Industrial and waste management activities have contaminated soil and groundwater. Subsurface contamination poses a continuing risk to human health and environment. Liquid contaminants can migrate through the soil matrix and leach into the ground water, while solid and semi-solid pollutants may be transported and dispersed through the subsurface. Because clean-up technologies, when available for subsurface containment can be costly and time consuming, it is necessary to examine other, possibly cheaper, ways to reduce the risk and protect human health and the environment at contaminated sites. Subsurface engineered barriers have been used to isolate hazardous waste from contact, precipitation, surface water and groundwater. Barriers are currently used for the containment of contaminated waste, as an interim step while final remediation alternatives are developed or decided and in coordination with treatment technologies. Engineered barriers are constructed containment systems that control horizontal migration of groundwater. Vertical barriers typically used to control sources of hazardous waste are soil-bentonite, soil-cement bentonite, cement bentonite, sheet pile (steel or high density polyethylene - HDPE) and clay barriers.