Formatted Title
Using the Conceptual Site Model to Visually Assess and Communicate “Source-Migration Pathway-Receptor Linkage”: A Case Study
Background/Objectives
Background/Objectives: Conceptual site models (CSMs) synthesize relevant information about potentially contaminated sites so that an interpretation of “source-migration pathway-receptor linkages” can be made. The purpose of this case study is to provide examples of how analytical results collected during vapor intrusion investigations can be evaluated visually as a means of assessing these linkages. It also demonstrates the power of merging GIS database application techniques with CSMs as a tool not only for data assessment, but for the efficient presentation and communication of the results of those assessments to others.
Approach/Activities
Approach/Activities: The CSM discussed in this case study is associated with a residential neighborhood located in the Midwest. It is a representative example of a group of homes consisting of a multi-story stand-alone residence with an attached garage, basement, crawl space, restrooms and living spaces. Sample types and locations considered for inclusion in the CSM included:
- Exterior soil gas samples
- Sewer gas samples
- Sub-slab vapor samples
- Crawl space vapor samples
- Indoor air samples
- Ambient air samples
Ratio plots of the relative concentration of COCs are used to visually evaluate the source-migration pathway-receptor linkages.
Results/Lessons Learned
Results/Lessons Learned: Combining analytical database management approaches with a unique GIS approach focused on CSM elements, demonstrates that large, often complicated, vapor intrusion datasets can be easily evaluated and communicated to mitigation specialists, property owners, regulators and other stakeholders. The case study demonstrates the limitations of relying on a limited COC list, how an expanded COC list can help to identify preferential pathways, and how to identify and communicate the presence of indoor air sources.