Superfund Site Assessment Activities
Pre-CERCLA Screening (PCS)
A Pre-CERCLA Screening (PCS) is a relatively low-cost initial collection and review of existing information for a potential Superfund site. The PCS helps determine whether the site should be addressed under the federal Superfund program or under another federal, state or tribal cleanup program, and whether the site should be entered into the Active site inventory in EPA’s Superfund database for further remedial assessment.
PCS activities include reviewing existing information and collecting minimal additional information to determine whether a site warrants entry into the Superfund active inventory for further site assessment evaluation. PCS activities generally apply to non-Federal facility sites.
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Preliminary Assessment (PA)
The preliminary assessment (PA) involves gathering historical and other available information about site conditions to evaluate whether the site poses a threat to human health and the environment and/or whether further investigation is needed. The PA helps identify sites that may need immediate or short-term response actions. The PA also fulfills public information needs, and generally furnishes appropriate information about the site early in the site assessment process.
The PA is a relatively quick, low-cost compilation of existing information about the site and its surrounding area, with an emphasis on obtaining comprehensive information on targets – that is, people and resources that might be threatened by a release from the site. A PA generally involves a reconnaissance of the site and its environs. The scope of the PA must be sufficient to complete a number of tasks:
- Review existing information about the site
- Conduct a site and environs reconnaissance
- Collect additional information about the site, with an emphasis on target information
- Evaluate all information and develop an HRS site score
Site Inspection (SI) and Expanded Site Inspection (ESI)
The objective of the site inspection (SI) is to gather information to support a site decision regarding the need for further Superfund action. The SI includes the collection of field data from a suspected hazardous waste site to confirm or deny the presence of contamination and to further characterize contaminants, migration pathways, and background contaminant level. The SI serves as a further screening activity to determine what steps, if any, need to occur next at the site. If a site cannot be adequately characterized using standard SI methodologies, an expanded site inspection (ESI) can be performed. An ESI collects additional data beyond that collected in the SI to evaluate the site for HRS scoring such as the installation of groundwater monitoring wells. The SI is not a study of the full extent of contamination at a site or a risk assessment.
Both the SI and ESI actions are encouraged to combine site assessment and removal evaluation activities when warranted by site conditions to reduce repetitive site characterization tasks and costs. Similarly, the SI and ESI actions may be combined with the PA at sites where it is warranted and where time and cost efficiencies can be gained.
The SI consists of four major activities:
- Review available information, including analytical data
- Organize project team and develop SI work plan, sample plan, health and safety plan, and investigation-derived wastes (IDW) plan
- Perform field work to visually inspect the site and collect samples
- Evaluate all data and prepare the SI report
Integrated ESI/Remedial Investigation (ESI/RI)
The integrated ESI/RI is an assessment consisting of an ESI and an RI. The ESI/RI is used to expedite remedial response by gathering site characterization data common to both ESI and RI activities in one step, thereby expediting the later collection of data when comprehensive RI activities are performed. The goal of ESI/RIs is to save time and costs characterizing sites when compared to the traditional, sequential ESI-NPL Listing-RI process. ESI/RIs facilitate but do not replace RIs and are recommended at sites where conditions indicate that the HRS score will be above 28.50 and a remedial response will be needed.
Site Reassessment
A Site Reassessment includes the gathering and evaluation of new information on a site in the SEMS Active or Archive site inventory that was previously assessed under the federal Superfund program to determine whether further Superfund attention is needed. A Site Reassessment serves as a supplement to previous assessment work and not as a replacement for traditional assessment activities (e.g., Preliminary Assessment, Site Inspection). The intent of the Site Reassessment is to document the expenditure of Superfund resources on older sites where the EPA has received new information or learned that site conditions have changed. The activity is also used to further assess decisions made after reviewing new site information and is expected to average one year from start to completion.
Hazard Ranking System (HRS)
The Hazard Ranking System (HRS) is the principal mechanism that the EPA uses to place uncontrolled waste sites on the National Priorities List (NPL). It is a numerically based screening system that uses information from initial, limited investigations - the preliminary assessment (PA) and the site inspection (SI) - to assess the relative potential of sites to pose a threat to human health or the environment. Any person or organization can report spills and environmental violations and petition the EPA to conduct a preliminary assessment.