Containment treatments are often performed to prevent, or significantly reduce, the migration of contaminants in soils or ground water. Containment is necessary whenever contaminated materials are to be buried or left in place at a site. In general, containment is performed when extensive subsurface contamination at a site precludes excavation and removal of wastes because of potential hazards, unrealistic cost, or lack of adequate treatment technologies.

Containment treatments offer quick installation times and are typically a low to moderate cost treatment group. Unlike ex situ treatment groups, containment does not require excavation of soils, that lead to increased costs from engineering design of equipment, possible permitting, and material handling. However, these treatments require periodical inspections for settlement, ponding of liquids, erosion, and naturally occurring invasion by deep-rooted vegetation. Additionally, ground water monitoring wells, associated with the treatments, need to be periodically sampled and maintained. Even with these long-term requirements containment treatments usually are considerably more economical than excavation and removal of the wastes.

Containment treatments for soil, sediment, bedrock and sludge include landfill cap and landfill cap enhancements. These treatments are discussed in more detail in Section 4. Completed projects for other treatment technologies for soil, sediment, bedrock and sludge are shown in Table 3-10.