In a report released on July 20, 2016, the Environmental Protection Agency (EPA) found moderate or severe corrosion in diesel underground storage tanks (USTs). The report stated that the corrosion, which was found inside both steel and fiberglass UST systems, can cause equipment failure by preventing proper operation of release detection and prevention equipment. If left unchecked, EPA said, corrosion could cause UST system failures and releases, which could lead to groundwater contamination.
EPA’s report shows that 35 of 42 – or 83 percent – of the USTs studied exhibited moderate or severe corrosion, but less than 25 percent of owners were aware of corrosion prior to the internal inspection.
Even absent a release of fuel to the environment, severe corrosion poses concerns for owners, EPA said. Corrosion increases servicing and equipment maintenance costs for UST system owners. Anecdotes suggests that dispenser filters may become clogged with corrosion debris that resembles coffee grounds, resulting in filters needing to be changed more frequently. Other equipment may need to be repaired more often and sometimes may need to be prematurely replaced.
Importantly, the report does not pinpoint a cause of the corrosion, which UST owners began reporting in 2007. There are likely multiple underlying factors contributing to corrosion, including:
-the reduced sulfur content in diesel, which could be allowing microbial life to proliferate in ultra-low sulfur diesel tanks and, through microbiologically-influenced corrosion, cause corrosive conditions that were less possible when diesel had a higher sulfur content.
-greater biofuel content in diesel fuel, though EPA specifically notes that validation of this theory based on the report released on July 20 "would be speculative."
The report contains a variety of recommendations for tank owners that NATSO members should find helpful. EPA recommends owners check inside their tank systems and further investigate the condition of their diesel fuel tanks. EPA's UST website provides more information and links to additional documents describing action tank owners can take to minimize corrosion and associated risks. Additionally, the Coordinating Research Council, funded by the American Petroleum Institute, recently released a preventative maintenance guide for diesel storage and dispensing systems.
NATSO members who have additional questions on this issue can contact NATSO's regulatory counsel David Fialkov at firstname.lastname@example.org / 703-739-8501. NATSO is happy to arrange a members-only visit, conference call, or webinar with EPA's Office of Underground Storage Tanks officials to provide more information on this important topic if members are interested in that as well.
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