Soil Vapor Surveys for Cost Cutting Site Characterization

Abstract

New technical approaches and cost cutting alternatives are being utilized in the environmental engineering field. These unique methods are used in the mapping, delineation and remediation of contaminated sites. One development which has seen a sudden increase in the recent past is the utilization of soil vapor surveys to map contamination plumes in the vadose zone. Using the soil vapor method, industrial sites and sites containing potential buried drums or underground storage tanks can be quickly evaluated for the presence of volatile contaminants. This information can be especially important in property transactions where buyers desire to protect themselves from potential costly clean-ups. The soil vapor survey consists of sampling volatile vapors in the vadose zone and analysis of the vapors on analytical instruments. The survey targets those contaminants which have volatilized from residues in soils or shallow ground water. One method of sampling soil vapors is penetrating five to ten feet into the sub-surface with a sampling probe. Upon collection of the vapors, concentrations may be measured. The analytical instruments can range from simple Drager Tubes to a laboratory gas chromatograph. The methodology for selecting sampling locations depends on the site. An underground storage tank facility may be approached by completing sampling locations at the tank pit and near the product lines. A grid sampling location map may be used to sample a property with an unknown organic content. Soil vapor surveys have limitations in regards to soil types, sampling depths and constituents being analyzed. However, given the proper conditions, soil vapor surveys can provide qualitative data at lower costs than alternative methods.