Environmental

We have extensive experience in characterizing the subsurface to map contaminant plumes related to landfill seepage, acid rock drainage, unintentional waste discharges, and spills of non-aqueous phase liquids (LNAPLs and DNAPLs).  In most instances, we use conventional electrical and electromagnetic methods for these applications including electrical resistivity, electromagnetic induction, and ground penetrating radar.  In special cases, we have adapted the traditional methodology to solve specific problems, such as using steel-cased wells as long electrodes for mapping infrastructure rich areas.

In addition to environmental characterization, we can provide time-lapse monitoring of subsurface fluid injections (e.g., corrective action of environmental contamination, installation of grout curtains, permeable reactive barriers, etc.).  HGI fabricates specialized resistivity hardware to ensure that the relevant dynamics of fluid migration in the subsurface is captured.

Example

3D Imaging of a Contaminant Plume:

Following is an example of the mapping of a subsurface contaminant plume using high resolution resistivity (HRR).The purpose of the investigation was to locate a contaminant waste plume composed primarily of inorganic salts (>90% nitrate), heavy metals, and radioactive metals. The HRR data, interpreted from 42 lines of data (about 20 line-kilometers) strategically placed around the site to maximize information, showed a conductive region throughout the site at depths from 25 to 45 meters below ground surface.  The range of apparent resistivity was from 48 to about 1680 ohm-meters, and volume estimates of the conductive plume showed that the effluent distribution correlated well with the 163-175 ohm-m contour level.

Mapping of a subsurface contaminant plume using high resolution resistivity (HRR).