UNDERGROUND STORAGE TANK SURVEY

Recently a consulting company asked to employ our services at a site in downtown Los Angeles to conduct a geophysical evaluation for the presence of underground storage tanks. Historically, the site was used as an auto repair facility. It is our understanding that Sanborn Fire Insurance Maps indicated the former location of a UST on the southern portion of the facility. The client indicated that a geophysical survey was conducted previously, but that no useful data was acquired. It was suspected that the UST was removed, however, confirmation was needed to focus sampling plans and to get closure on the site.

GPR traverses conducted over the site indicated one excavation area near the end of a cut off pipe (possibly a former vent or product line).  In addition to radar records indicating a possible excavation, a low conductivity response was detected with the *M-scope (indicating a less conductive backfill) and an asphalt patch with slight subsidence and cracking was noted encompassing the same area.