Methods of Determining in Situ Oxygen Profiles in the Vadose Zone of Granular Soils

Abstract

This paper describes seven different methods evaluated to determine in situ oxygen profiles in the vadose zone at a site consisting of granular soils. The techniques investigated included both permanent installations (four) and rapid deployment drive probes (three). The soil and ground water conditions at the site are first described followed by details of the design, deployment and sampling for each method. Typical oxygen profile results obtained from the different methods are presented and compared based on their ease of deployment, efficiency, repeatability, and reliability. Based on the results of this study, the most reliable and consistent sampler types tested were two of the permanent installation designs. The ease of construction and relatively low material costs of these particular methods, combined with their simplicity, relative quickness and accuracy of sampling make them superior to the others tested. The rapid deployment drive probe methods were prone to errors due to short circuiting, damage during deployment or sampling difficulties. However, when care was taken to minimize these factors, some of these methods also produced reliable and consistent results.