Ever since combustion engines became popular, most gasoline and
diesel tanks at vehicle service stations have been buried underground.
Gas stations proliferated in the 1950s and 1960s, but without any
regulation. Early tanks—made of steel—were installed without
corrosion, spills or overfills. Many of these tanks would eventually
leak gasoline and oil containing toxic chemicals such as benzene,
toluene and lead which can leach into groundwater, posing a threat to
the environment and human health. Nearly 2 million Oregonians get their
drinking water from groundwater sources. Underground tank leaks are one
of the top threats to safe drinking water.
Federal laws governing safe tank storage began regulating the
industry in the 1980s when the U.S. Environmental Protection Agency
required the registration of underground storage tanks. In Oregon 31,000
regulated tanks were registered. Of this number, 25,000 tanks were
removed or decommissioned with DEQ oversight through the
Underground Storage Tank
Program. During the decommissioning
process, 7,000 petroleum-contaminated sites were discovered from leaks
and spills. To date, DEQ staff have overseen the successful cleanup of
approximately 90 percent of these sites, with others in the cleanup
The latest EPA regulations require underground storage tanks to be
inspected every three years and to have double-walled construction with
corrosion protection, overfill/spill containment equipment and leak
detection monitoring equipment. DEQ underground storage tank staff
conduct onsite inspections of some 6,000 tanks throughout the state,
confirming their safe operation and overseeing the cleanup of any leaks.
The good news for Oregon residents is that the number of leaks and
cleanups has dropped dramatically in the past decade. New regulations
and monitoring are ensuring greater protections than ever for our
environment and drinking water.
Click chart to enlarge. Thanks to the
introduction of federal laws regulating the underground storage of
tanks, the number of reported leaks from underground gasoline and oil
tanks in Oregon has decreased dramatically over the past two decades.
Site restoration often involves removal of contaminated
soil. Cleanup of the McCormick & Baxter Creosoting Co. site in
north Portland resulted in the removal of 33,000 tons of highly
Cathy Rodda, an inspector with DEQ's Undergound Storage Tank
Program, oversees excavation of buried tanks at a defunct gas
station in Eugene.