UST (underground storage tank) closure and removal

Underground Storage Tanks (USTs)

There are many underground storage tanks (UST) throughout the United States and abroad. They commonly contain diesel fuel, gasoline, chemicals, and hazardous/radioactive liquids. There have been and continue to be problems with leaking UST's and this offers opportunities to implement remediation technologies we have discussed as well as new or emerging technologies. For example, at the Department of Energy's Hanover nuclear energy facility, much effort is focused on attempting to design remediation technologies to stabilize UST's filled with hazardous and radioactive liquids.

UST's are commonly found at gas stations, truck facilities, sanitary landfills manufacturing facilities, etc. Where there are trucks stored or parked, UST's can usually be found. They store fuel (diesel, gasoline) for the vehicles. They are placed underground to allow vehicles to drive around the facility without being impeded by the tanks.

The UST's come in various sizes and 500 to 10,000 gallon tanks are very common. At the Hanover site they can range up to 1 million gallons. Gas stations normally have 10,000 gallon gasoline tanks.

In the last year or two, all new UST 's had to meet strict construction guidelines and have to be monitored for any possible spill or leak of the contents. Also, all existing UST's needed to be upgraded to meet new guidelines for operation or be removed. This upgrade included having cathodic protection (preventing the development of holes in the tanks from moisture in the soil), double wall construction or something else, and monitoring for spills or leaks. This monitoring can be in the form of groundwater monitoring wells around the UST's, interstitial protection, inventory control, and others.

As mentioned earlier, the opportunities to attempt new technologies to clean up leaks and spills are plentiful, provided the local regulatory agency(s) is willing to allow their use. It would require working close with the regulatory agency to implement any new technology.

When removing a UST from the ground, a certain protocol for removal needs to be followed. For example, in most cases the state needs to be informed of the intention to remove a UST well in advance so they can schedule to be present. When removal takes place, the soil surrounding the tank needs to be sampled and tested for contamination as well as the groundwater beneath the UST. If contamination does exit, a plan or corrective action needs to be developed to remove the contamination. The plan needs to be sent to the state/local regulatory agency for approval before anything can be done, except if there is an emergency which requires immediate action. After approval of the plan by the agency, work can begin. When the work is completed, a report needs to be completed, signed by a Professional Engineer or Professional Geologist and given to the agency for final approval. In most cases of a release from a UST, the regulatory agency needs to be notified within 24 hours of the release.