Cone Penetrometer Testing for Characterization and Sampling of Soil and Groundwater

Cone penetrometer testing (CPT) is an alternative method to drilling for subsurface characterization of hazardous materials release sites. CPT provides higher quality data at lower cost and with fewer health and safety concerns than conventional drilling. CPT basically consists of pushing a cone-tipped, steel rod into the subsurface soils at a constant velocity and measuring the stresses used for automatic determination of soil types. CPT with concurrent measurement of pore pressure is used for determining hydraulic head and other parameters. Several methods for in situ screening of subsurface contaminants have been added to CPT equipment, including vapor sampling, laser induced fluorescence (LIF), and pore water resistivity. CPT is also used for “direct push” sampling of soil and groundwater and for installation of small diameter “well points.” CPT can be used with an assessment strategy that parallels that of conventional drilling; however, the in situ testing capabilities of CPT lend themselves to a more comprehensive assessment strategy that minimizes soil and groundwater sampling. A case study illustrates this comprehensive assessment strategy.