Methodology for analyzing soil vacuum data at VOC-contaminated sites
- Bechtel Environmental, Inc., Los Angeles, CA (United States)
Proper design of a soil vapor extraction (SVE) treatment system at a site contaminated with volatile organic compounds (VOCs) hinges on the effective characterization of vapor flow through the subsurface. The collection and analysis of soil vacuum data during vapor extraction provides the basis for this characterization. Although the collection of soil vacuum data is routinely performed across the industry at VOC-contaminated sites, a systematic, both quantitative and qualitative, method of analyzing vacuum data typically is not employed. Thus, a comprehensive analysis is presented for the characterization of vapor flow through the subsurface. This methodology will include: (1) the interpretation of vacuum data using statistical analysis to infer site stratigraphy and soil permeability; (2) the diagnosis of vapor flow ``short-circuits``; and (3) flow path mapping. Statistical analysis will include the determination of 95% confidence intervals using the collected SVE data. The confidence interval will be used to determine if deviations of individual data points from the linear trend are statistically significant. Once a region of homogeneity is delineated through the statistical analysis, flow net construction will be performed. Equipotential lines will be drawn using collected SVE data, and subsequently, flow channels can be mapped to show the distribution of vapor flow through the subsurface. Case studies are presented to demonstrate how vacuum data are used to characterize subsurface vapor flow at VOC-contaminated sites. Using the vacuum data collected at these sites, the degree of soil homogeneity and vapor flow influence are characterized.
- OSTI ID:
- 215548
- Report Number(s):
- CONF-951139--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Case study: Vacuuming for VOCs
Superfund Record of Decision (EPA Region 9): El Toro Marine Corps Air Station, Operable Unit 2A (Site 24-VOC source area vadose zone), El Toro, CA, September 29, 1997