Field evaluation of 1.75 groundwater profiler and field screening device for on-site contamination profiling of chromium(VI) in groundwater

Abstract

Groundwater contamination by toxic heavy metals pose serious health hazards to humans and the environment. The remediation of contaminated groundwater requires effective characterization of the concentrations and spatial distribution of heavy metals. Groundwater samples from long screening monitoring wells do not provide an accurate representation of the distribution of heavy metals with depth, as the data obtained from the well are an average along the screen length. This study reports the development and application of two new technologies, a direct push 1.75 groundwater profiler (GWP) that obtains groundwater samples from multiple depths in a single push, and a portable field screening device that uses novel disposable sensors to facilitate rapid, cost-effective, on-site detection of heavy metals in groundwater, surface water, and sediment pore water. Extensive fieldwork was performed at a chromium(VI)-contaminated site to evaluate and validate these two technologies for on-site contamination profiling of Cr(VI) in groundwater. A preliminary investigation was performed with an OIHPT logging tool to determine formation lithology and relative permeability for identifying potential groundwater sampling intervals and contaminant migration pathways in the subsurface. Groundwater samples from selected depth intervals were collected and analyzed by an outside laboratory analysis for total chromium and hexavalent chromium as per EPA standards 6020 (SW) and 7196, respectively. The excellent comparison of the field results with the laboratory test results confirm the potential of these technologies in obtaining high resolution site characterization data to improve the management of heavy metal-contaminated hazardous sites.