Locating Abandoned Underground Storage Tanks (USTs)

A hydrogeophysics staff member drives an ATV pulling HGI’s Geophysical Operations cart, which consists of a magnometer and GEM electromagnetic sky. The survey is to locate subsurface infrastructure.

G.O. Cart equiped wtih Electromagnetic and magnetic Sensors using GPS Heads-up Navigation towed with an ATV

Will unknown abandoned underground storage tanks delay your project?

Article by:   Jeremy Strohmeyer | Senior Project Manager | hydroGEOPHYSICS


As engineering and consulting professionals, we grapple with the challenges of designing a project on top and across unknown subsurfaces. Geologic features, visual inspections, infrastructure, and historical documents can only give us clues to what is happening beneath our feet. Geophysical tools (such as electromagnetics and ground-penetrating radar) can offer an inexpensive way to understand large areas of the subsurface quantitatively.

Old or abandoned underground storage tanks (USTs) can cause obvious problems for site development.

Old or abandoned underground storage tanks (USTs) can cause obvious problems for expanding right-of-ways, future development, and environmental compliance if their locations are not accurately determined before drilling investigations or construction. Electromagnetics (EM) and ground-penetrating radar (GPR) are two methods that are frequently used to identify the presence or absence of USTs on a site.

EM data are acquired by generating a current in a transmitting coil and measuring the response from the subsurface in a receiving coil. These coils are frequently housed in a single unit, which can be carried or towed by a single operator fairly rapidly over an entire site. Metallic objects, such as steel USTs, will be identified as high amplitude responses in the EM data. GPR works in a similar fashion to EM methods, in that a transmitting antenna sends pulses of electromagnetic energy into the subsurface, and a receiving antenna measures the response of those pulses reflected back off of contrasts in electrical properties in the subsurface. A metallic UST will usually be characterized by a high amplitude hyperbolic response in a GPR profile. GPR data is frequently collected in conjunction with EM data over select EM anomalies to better characterize the cause of the EM response, and to provide a more accurate representation of the depth and size of the target.

Electromagnetics (EM) and ground-penetrating radar (GPR) are generally a quick, inexpensive way to determine where old abandoned USTs are located on a property.

EM and GPR are typically a quick, inexpensive way to determine where old abandoned USTs may exist in your project site. With accurate and timely information in hand, the effort to plan boring locations or excavate USTs as part of remediation efforts becomes fast and easy. We put our many years of experience to work for you through custom-fit EM and GPR surveys for UST location, enhancing site characterization need while saving you time and reducing costs.


The image shows a plan-view representation of EM data and GPR data collected over three high amplitude EM anomalies. The GPR data provides supporting evidence for the presence of three USTs, their approximate depths and dimensions.

EM data are collected across the accessible areas of a right-of-way expansion. GPR data are collected over select EM anomalies to determine possible causation. The combination of EM and GPR identified three USTs in the survey area and provided approximate depth and dimension information.



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About the Author: Jeremy Strohmeyer | hydroGEOPHYSICS

Jeremy Strohmeyer is a Senior Project Manager for hydroGEOPHYSICS, Inc (HGI). He has a broad range of experience with surface, underwater, and borehole near-surface geophysical methods. Jeremy has a particular interest in seismic methods, including: refraction, reflection, and surface wave methods.

Jeremy is a licensed geologist in the states of Arizona, Kansas, Missouri, and North Carolina. He has participated in committees and leadership positions in several organizations, including EEGS, AEG, SEG, SAME, and ITE. Jeremy holds a BS in Geology & Geophysics and an MS in Geology & Geophysics from the University of Missouri-Rolla.

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