Region 8

HH: Site Conceptual Model

In this step, the risk assessor prepares a schematic diagram that does the following:

  • Identifies the primary source of contamination in the environment (e.g., releases from a leaking storage tank, waste material poured on the ground).
  • Shows how chemicals at the original point of release might move in the environment (e.g., a chemical in soil might penetrate down into groundwater or might volatilize into air).
  • Identifies the different types of human populations (e.g., resident, workers, recreational visitors) who might come into contact with contaminated media.
  • Lists the potential exposure pathways (e.g., ingestion of contaminated water, inhalation of chemicals in air, dermal contact with contaminated soil) that may occur for each population.

This conceptual model is used to plan the risk assessment and associated data collection activities and is often revised periodically as data become available at a site. Examples of Region 8 human health site conceptual model diagrams and other useful resources are provided below.

Examples of Region 8 Site Conceptual Models


RAGS I Part A (EPA/540/1-89/002, December 1989)

Reuse Assessments:  A Tool To Implement The Superfund Land Use Directive (PDF) (Memorandum, OSWER 9355.7-06P, June 2001) (24 pp, 83 K, About PDF)

Model Statement of Work for RI/FS Baseline Risk Assessments of Human Health (Region 8 Superfund Technical Guidance RA-01, September 1994)

Model Site Conceptual Model for RI/FS Baseline Risk Assessments of Human and Ecological Health (Region 8 Superfund Technical Guidance RA-05, May 1995)

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