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Aging Underground Storage Tanks

Many Underground Storage Tanks (USTs) that have aged 20 or more years are subject to a lot of wear and have potential leaks. A study conducted in October 2014 by a workgroup of the Association of State and Territorial Solid Waste Management Officials (ASTSWMO) found the potential affect of aging USTs to owners, operators, and State UST programs. The purpose of the study was to do determine if there was a correlation between older UST infrastructures and a larger risk of leaks.

As shown in Figure 1 below, the study found that in eight states 59% of the tanks are older than 20 years.

During this study it was also found that the collection and maintenance data collected by each state about USTs varied greatly, so the Workgroup took a more in depth look into the aging infrastructure. The evaluation found the age of the UST piping in four states, CO, MO, UT, and VT, was newer than the age of the UST itself and that the average age of the pipes is 17.7 years.

*Credit for charts above goes to ASTSWMO

The Workgroup found that most states did not record the source and cause of leaks of in-use USTs, but this study did not include an analysis of “source and cause” data that states are required to report according to the 2005 Energy Policy Act. There are only a handful of studies that investigated this data and all have concluded that other components besides the tank, such as pipes, joints, and gaskets, caused most UST leaks. For more information about how an investigation and documentation into the source and cause of a leak, readers can refer to ASTM E2733-10(2015), “Standard Guide for Investigation of Equipment Problems and Releases for Petroleum Underground Storage Tank Systems.”

From a survey conducted by the Workgroup it was found most states do not require owners to replace USTs after they’ve reached a certain age or provide incentives to do so. Some owners do not have the financial capability to replace their aging UST systems.

To figure out if the age of USTs is a factor in the risk of leaks, more information must be collected from states. States need a uniform method of investigating and recording this information to get a better understanding in what is the source and cause of leaks. Monitoring of tank systems should continue and investigation and reports should be conducted when a spill occurs.

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