The overall objective in remediating hazardous waste sites is the protection of human health and the environment by reducing risk. There are three primary approaches which can be used in site remediation to achieve acceptable levels of risk:

• the hazardous waste at a site can be contained to preclude additional migration and exposure
• the hazardous constituents can be removed from the site to make them more amenable to subsequent ex situ treatment, whether in the form of detoxification or destruction
• the hazardous waste can be treated in situ (in place) to destroy or otherwise detoxify the hazardous constituents

Each of these approaches has positive and negative ramifications. Combinations of the three principal approaches may be used to address the various problems at a site. There is a growing menu of technologies available to implement each of these remedial approaches. Given the complexity...