Vapor intrusion (VI) occurs when VOCs in soil gas enter overlying buildings and contaminate indoor air. Applied for over 30 years, SVE has been selected as a remediation technology at more than 285 Superfund sites and is a continuing topic of research. Soil vapor extraction (SVE) is the most common in situ remediation technology for addressing solvents, petroleum products, and other relatively volatile organic compounds (VOCs) contaminating unsaturated soil. These findings suggest that SVE affects distant VI entry points with little observable impact on differential pressures and without relying on subslab VOC concentration reductions. These cases also demonstrated mitigation effects across a four-lane avenue with subsurface utilities. Indoor air quality improvements were evident in buildings 100 to 200 feet away from SVE including those without a measurable reversal of differential pressure across the slab or substantial reductions in subslab VOC concentration. Data indicate a measurable (5 Pa) influence of SVE on subslab/indoor pressure differential may occur but is not essential for effective VI mitigation. We determined that SVE effectively mitigates offsite VI by intercepting or diluting contaminant vapors that would otherwise enter buildings through foundation slabs. The primary objective was to determine if SVE could provide VI mitigation over a wide area encompassing multiple buildings, city streets, and subsurface utilities and eliminate the need for individual subslab depressurization systems. Through a series of alternating extraction (SVE on) and rebound (SVE off) periods, this field study explored the relationship and aspects of SVE applicable to VI mitigation in a commercial/light-industrial setting. However, the relationship between residual mass in the subsurface and VI is complex. Soil vapor extraction (SVE) is effective for removing volatile organic compound (VOC) mass from the vadose zone and reducing the potential for vapor intrusion (VI) into overlying and surrounding buildings. Vacuum Readings with Handheld Micromanometer (in w.c) Step Extraction Testing Start and Stop Times for Individual Screens and Applied Vacuums Operational History and Mass Removal for Individual Extraction Wells Vapor Monitoring Point and Groundwater Monitoring Well Depths PCE Concentration Histories at IA06 and SS09 Indoor to subslab differential pressure measurements (daily averages) over time with main SVE operational events, subslab port SS06įigure S11. Indoor to subslab differential pressure measurements (daily averages) over time with SVE operational events, subslab ports a) SS01, b) SS02, c) SS07, d) SS08, e) SS09, f) SS10įigure S10. Modeling Results for the Deep Soil Gas Extraction Testįigure S9. Model Fit to the Deep Soil Gas Extraction Testįigure S8. Modeling Results for the Shallow Soil Gas Extraction Testįigure S7. Model Fit to the Shallow Soil Gas Extraction Testįigure S6. Multilevel PCE Vapor Concentration Histories Northwest (DWB-VP1) and South (VP14) of the Sitesįigure S5. Composite Vertical Profiles of Baseline Vapor Concentrations from PneuLog near the Primary Source Releaseįigure S4. Comparison of TO-15 and Method 18 Results for PCE Concentrationįigure S3. Detailed Site Map with Study Infrastructure Locationsįigure S2.
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