Log in | Subscribe | RSS feed

What’s New

US EPA confirms corrosion problem in diesel fuel underground storage tanks

25 July 2016

The US Environmental Protection Agency (EPA) released a report on corrosion inside diesel fuel underground storage tanks (UST). The EPA investigation found that moderate or severe corrosion could affect metal components inside both steel and fiberglass underground tank systems. Corrosion inside USTs can cause equipment failure and, if left unchecked, could cause fuel releases that could lead to groundwater contamination, warned the agency. Underground tank releases have historically been a leading cause of groundwater contamination.

The EPA’s report shows that 35 of 42, or 83%, of the USTs studied exhibited moderate or severe corrosion, but less than 25% of owners were aware of corrosion prior to the internal inspection. The agency issued a notification that recommends owners check inside their tank systems and investigate the condition of their diesel fuel tanks.

In several cases, the affected tanks also contained sludge and particles, looking like coffee grounds, which were clogging the tank fuel filters.

The study has not identified a specific cause of corrosion in diesel tanks, although it concluded that microbiologically-influenced corrosion could be largely responsible. The EPA said it is continuing to work with partners in the UST community, industry, and scientific experts on additional research about the cause of corrosion. With EPA support and input, the Coordinating Research Council (CRC) will develop the next phase of the research.

The research was conducted by Battelle and the EPA Office of Underground Storage Tanks (OUST). In a 2012 study, Battelle suggested that the corrosion was likely caused by the dispersal of acetic acid throughout USTs. The acetic acid was thought to be produced by bacteria feeding on low levels of ethanol contamination. In the current study, ethanol was found to be present in 90% of the 42 samples, suggesting that cross-contamination of diesel fuel with ethanol is likely the norm, not the exception.

The problem of corrosion in diesel fuel storage systems in the United States started around 2007. In the affected systems, corrosion is coating the majority of metallic equipment in the tanks, such as submersible turbine pumps, drop tubes, sensor probes and dispenser components. While initially attributed to the 2006 launch of ultra-low sulfur diesel, the problem was later linked to the contamination of diesel USTs by ethanol. Other potential contributors that have been cited include salt contamination, corrosion inhibitor depletion and poor housekeeping.

Source: US EPA