1. Closing Session Modeling Vapor Attenuation Workshop Annual International Conference on Soils, Sediments, and Water October 19, 2004 Amherst, MA

2. Workshop Goals Scope = OSWER VI Guidance Purpose: Improve OSWER VI Guidance Objectives = Evidence-based Improvements Henry Schuver, US EPA, OSWER-OSW Annual Int. Conf. on Soils, Sediments and Water October 19, 2004 - Amherst, MA

3. Overview: What Is The Intent of This Guidance? “a tool to … conduct a screening evaluation as to whether or not … pathway is complete and, if so, whether it poses an unacceptable risk” For Current and Future conditions Today’s Objective: Use evidence to Improve Guidance More cost-effective exposure reductions (via screening) i.e., fewer false positives (w/ min. false negatives)

4. Closing Topics Lenny Siegel – Community Perspective Todd McAlary – Future directions for Assessing Vapor Intrusion Ian Hers – Mass Flux Considerations Henry Schuver – Potential VI Guidance Appendices

5. VI Guidance – Potential Appendices Additional Guidance for Risk Assessment Underground Storage Tanks and Petroleum Hydrocarbons Use of Real-Time Measurement Methods Soil-gas Sampling Methods - Recommendations & Methods Review

6. VI Guidance – Potential Appendices Use of Superfund Spreadsheets in Site- Specific Screening Screening for Future Land Use Extending Figure 3 to less than 5 ft depths and including Crawlspaces Considerations for Remedy Selection

7. VI Guidance – Potential Appendices Toxicity - Maintaining Current Values Practical Approaches to Determining Appropriate Sampling Methods Amount and Frequency of Data Needed for Confidence in Screening

8. iavi.rti.org rst@rti.org