2D ELECTRICAL RESISTIVITY AND HYDROLOGICAL SURVEY OF A SOLUTE PLUME’S MIGRATION PATHWAY THROUGH A SANDY LOAM WITHIN NACOGDOCHES COUNTY, TEXAS

A combined geophysical and hydrological study was conducted in a sandy loam near the campus of Stephen F. Austin State University in Nacogdoches, Texas. The study area contains three preinstalled monitoring wells and is located in the Sparta Sand member of the Eocene Claiborne Group, a regressive tract of the Eocene sea.

Electrical DC resistivity surveys were conducted across three fifty-six-meter-long traverses using AGI’s multi-electrode SuperSting R8 WIFI RES/IP/SP system, which allowed for rapid and reliable data collection. All resistivity lines were surveyed using the dipole-dipole array configuration, which has been proven to produce high-quality horizontal resolution. Over the duration of two weeks, specified quantities of a conductive solution were added into the infiltration pit and DC resistivity surveys conducted each day. DC resistivity data were processed and interpreted using AGI’s EarthImager 2D inversion software. The geophysical data acquired was paired with a hydrogeological survey of the area in order to accurately track the tendencies of a solute plume through the sandy loam. The data acquired provided specifics on the rate of infiltration as well as the migration pathway of any future contaminant spills.

The principal objective of the study is to track the flow pattern and rate at which a known conductive aqueous solution flows through a sandy loam. This geophysical study was done alongside a parallel hydrologic study that will improve tracking of the solute plume through the sandy loam and allow researchers to monitor any interaction with groundwater. Knowledge gained from this study will be able to be used to in contaminant spills.