Sample analysis and GPR detection for LNAPL contaminated soils

摘要

This paper shows a combination of laboratory measurement and field work for detection of LNAPL contaminated soils. The subsurface environment is contaminated heavily by LNAPL in the experiment site, where oil contaminated soils were partly filled more than 10 years ago. Three boreholes were drilled in the site. The core samples were recovered in the acrylic tubes in the boreholes, and were cut to make 161 sample units for laboratory analysis. The concentration of total petroleum hydrocarbons (TPH), electrical resistivity and relative dielectric constants have been measured in the laboratory. Soil cores sampled in the three boreholes clearly indicate that the TPH concentration has an inverse relation to the relative dielectric constant and a direct proportional correlation with the electrical resistivity. GPR data have high spatial resolution and enable us to image the shallow subsurface features. GRP data were acquired along 31 parallel lines with line-spacing 1 m. Three-dimensional GPR images are constructed to map LNAPL contamination. Thez results show that the LNPAL-contaminated area in the site can be mapped by the decreased radar signal amplitude combined with the borehole information.