MULTILEVEL SOIL-VAPOR EXTRACTION TEST FOR HETEROGENEOUS SOIL

The design, performance, and analysis of a held method for quantifying contaminant mass-extraction rates and air-phase permeability at discr ete vertical locations of the vadose zone are presented. The test conf iguration consists of a multiscreen extraction well and multilevel obs ervation probes located in soil layers adjacent to the extraction well . For each level tested an inflatable packer system is used to pneumat ically isolate a single screen in the extraction well, and a vacuum is applied to induce air flow through the screen. Test data include cont aminant concentration and flow characteristics at the extraction well, and transient or steady-state pressure drawdown data at observation p robes located at variable radii from the extraction well. The test met hod is applicable to the design of soil-vapor extraction (SVE) and bio venting remediation systems in a variety of geologic settings, particu larly stratified soils. Application of the test method at a gasoline-p olluted site located in the Piedmont physiographic region is described . Contaminant mass-extraction rates, expressed in terms of volatile hy drocarbons, varied from 0.16 to 14 kg/d.