nies, but presently derived from general tax revenues. However, at a majority of sites, the response is funded by private parties, either through a legally binding agreement to perform the remedy (e.g., an Administrative Order of Consent) or by reimbursing EPA for its remedial costs. At federal facilities cleanup is funded by the agency responsible for releasing contamination.

Initial Phases

A site regulated through CERCLA generally progresses through the Preliminary Assessment/Site Inspection, listing on the National Priorities List (NPL), site investigation (Remedial Investigation), remedial alternative assessment (Feasibility Study), remedy selection (Record of Decision), remediation implementation (remedial design followed by construction), and long-term monitoring and institutional controls until the site media concentrations are at or below unrestricted use levels (see Table 2-3). If there is an immediate threat to human health or the environment (“imminent and substantial endangerment”), the Preliminary Assessment/Site Inspection may trigger an interim emergency response.

The Remedial Investigation consists of detailed site characterization, while the Feasibility Study incorporates the evaluation of remedial alternatives that might meet remedial action objectives. The Remedial Investigation and Feasibility Study may be conducted concurrently, and, in any case, they influence each other. The Remedial Investigation generally includes a human health risk assessment and the determination of site-specific remedial action objectives. The Feasibility Study develops a series of remedial alternatives that describe the placement, timing, and remedial technology for cleanup activities, and it includes a detailed comparison of these alternatives with respect to criteria established under CERCLA regulations (see below).

Setting of Cleanup Goals and Selection of Remedies

CERCLA’s overarching groundwater remediation goal is to restore groundwater to its “beneficial use” “wherever practicable” (EPA, 2009a). A common beneficial use of groundwater, if conditions are appropriate, is that it be a source of drinking water. In addition, the groundwater plume “should not be allowed to migrate and further contaminate the aquifer or other media (e.g., vapor intrusion into buildings; sediment; surface water; or wetland)” (EPA, 2009a).

The alternative remedial strategies in the Feasability Study are evaluated based on a balancing of the nine criteria of the National Oil and Hazardous Substances Pollution Contingency Plan, usually called the National Contingency Plan (EPA, 1990):

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