Case Study: Underground Storage Tank Under An Addition
Our team at Trinity Subsurface is no stranger to performing locating services in unusual situations. A lot of existing conditions are based on years of construction, installations, renovations and additions. In the case of one property owner, we were called to locate an underground fuel tank for a customer looking to sell his building to a new buyer. As part of the terms of his sale, he needed to remediate an underground storage tank known to be under his property. Tank remediation involves removing the tank and any contaminated soil surrounding the tank. There was one issue with this, however: the tank location was unknown.
To make matters more complicated, this storage tank wasn’t suspected to be underneath a parking lot, yard, or easily accessible area: it was believed to be under an addition added to the building later in construction. When work is built on top of other work, especially with additions and remodels, subsurface planning isn’t always at the forefront. Utility plans aren’t always taken into account and information gets lost over time. This is typically the case with abandoned or unused utility lines. In this case, the lost tank becomes a gap in subsurface utility information. There have been a number of times we’ve been called out to examine areas where tanks are suspected but not confirmed. The client did not want to perform massive demolition efforts for any parts of the structure over top of the tank since he was working on selling the building, but not knowing where the tank was located made this tricky. What could we do to help?
In addition to utility lines, underground storage tanks, or USTs, can be easily located using ground penetrating radar, or GPR. We determined that GPR was the best tool for the job. Our team’s technicians are trained and equipped with the knowledge to perform ground penetrating radar scans and differentiating between the various subsurface structures we encounter. In addition, our team also uses split boxes to further confirm USTs. A split box can determine if the structure is made of metal. After furniture and obstructions were removed from the suspected area, we were ready to scan the area. Scanning the floor of the addition confirmed suspected conditions: the tank was underneath the building’s addition. Based on the scans, we roughly determined the tank to be a 275 gallon horizontal tank buried somewhere around 20 inches below grade. We also determined where the fuel lines entered the building. With this information, our client was better equipped to remediate the tank with no additional exploratory excavation necessary. Knowing where the tank and the associated fuel line is located also helps to minimize demolition to the floor if needed.
If your team needs utility or underground storage tank locating services, our team at Trinity Subsurface can help you determine the location of structures and utilities that may have been forgotten over time. Visit our website for more information on all of the utility services we offer to understand what’s underneath!
