According to the Environmental Protection Agency (EPA), there are roughly 705,000 underground storage tanks (USTs) in the United States alone - 25,000 of which hold hazardous substances, with the remainder containing primarily petroleum. While many of these are in-service, and well maintained and documented,  there are untold numbers of lost, forgotten, and unmonitored USTs.  These abandoned USTs may already be leaking, and if left unremediated will all eventually leak, and therefore represent a continuing threat to the environment.

Over the years, Enviroscan personnel have located over one thousand USTs.  Many times it is enough to simply determine whether, where and how many USTs are present beneath a site.  Other times, we are asked to provide accurate footprint outlines of USTs so that the soil around them can be probed and tested without increasing the risk of a release, or so that the tank can be removed with minimum site disturbance.

Since USTs come in different types (coated or uncoated steel and fiberglass), sizes (75 to over 30,000 gallons), and settings (e.g. beneath concrete pads, reinforced floors, asphalt, gravel, rubble, vegetation, etc.), Enviroscan performs UST hunts using a minimum of three independent techniques: magnetics to detect deeply buried steel USTs, highly focused metal detection to detect steel USTs on cluttered sites, and ground penetrating radar (GPR) to detect fiberglass tanks or tanks beneath highly cluttered sites or building floors. By mobilizing all three systems for any UST survey, we minimize the chances that any UST can escape detection.  We also mobilize and employ pipe tracing equipment to mark-out the piping associated with detected USTs.  The pipe tracing equipment also allows us to follow remote vent or fill pipes to USTs in odd locations (e.g. under streets, sidewalks, or buildings) that might otherwise escape detection.

In very unusual settings -- e.g. a fiberglass tank buried beneath sheet metal flooring – we have developed creative detection methods such as circulating hot air through the vent line and using thermal imaging of the floor to see the UST footprint.  In several other instances, we have performed microgravity measurements over buried USTs to determine whether they are filled with air, fluid, sand, or concrete (which have differing densities, and therefore produce differing gravitational anomalies).

On every survey, our goal is to paint or flag the outlines of any potential USTs and associated piping. Where documentation is required, we can also construct accurately scaled maps depicting UST footprints and piping traces, and reports describing our survey methodology and results.