Geophysical Methods Used to Locate Contaminant Flow Pathways

Challenge

Recently, an environmental consultant observed a liquid phase hydrocarbon (LPH) seep on the bank of a creek bordering an active industrial facility near State College, Pennsylvania. A UST had been located in an area of the site adjacent to the seep, but it had been removed several years prior. The consultant asked Mundell to perform a detailed geophysical survey of the site to locate any additional sources of contamination, and to map out the pathways those sources were using to transmit free product to the creek.

Action

Mundell selected electromagnetic metal detection (EMD), ground penetrating radar (GPR), and electromagnetic conductivity mapping to search for unknown source areas across the site. Additionally, two-dimensional resistivity and seismic refraction were used to examine the bedrock for topographic depressions, valleys, or fracture zones.

Results

By using the EMD and GPR techniques, Mundell was able to locate the previous tank pit, and a previously unkown UST. The conductivity results indicated where shallow soils were impacted, including the previous tank pit location. Finally, the resistivity and seismic data showed where bedrock features were transporting the LPH to the creek. The client was then able to use this data to accurately install their remediation system and clean up the site.