FORMER UNDERGROUND STORAGE TANK EXCAVATION SURVEY

Recently a consulting company asked to employ our services at a site in Carson, California to conduct a geophysical evaluation for the presence of an excavation associated with the removal of several underground storage tanks. Historical records indicated that several USTs were removed from one large excavation in the asphalt parking lot at the southeast corner of the facility. The exact location of the former tank pit was not known.

GPR traverses were conducted approximately every .5 meter on a 20 by 22 meter grid over the site. Data cross sections and time slices were successful in illustrating two possible product lines extending away from the building and terminating at a large excavation (note also the water line trench extending across the excavation).  In addition to radar records indicating a possible excavation, a low conductivity response was detected with the *M-Scope (indicating a less conductive backfill).