Oregon DEQ Removes Leaking Underground Storage Tanks to Prevent Groundwater Contamination

Environmental Challenge

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 protection from 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.

Success Story

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 process.

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 contaminated soil.

Cathy Rodda, an inspector with DEQ's Undergound Storage Tank Program, oversees excavation of buried tanks at a defunct gas station in Eugene.