L.U.S.T. FOR DEATH:

Almost every gas station eventually pollutes the earth beneath it, experts told Grist. The main culprit: the underground storage tanks that hold tens of thousands of gallons of fuel, one of the most common sources of groundwater pollution. Typically, two or three of these giant, submarine-shaped tanks are buried under a station to store the gasoline and diesel that gets piped to the pump. A large tank might be 55 feet long and hold as many as 30,000 gallons; a typical tank might hold 10,000 gallons. Leaks can occur at any point -- in the storage tank itself, in the gas pumps, and in the pipes that connect them. Hazardous chemicals can then spread rapidly through the soil, seeping into groundwater, lakes, or rivers. Even a dribble can pollute a wide area. Ten gallons of gasoline can contaminate 12 million gallons of groundwater -- a significant risk, given that groundwater is the source of drinking water for nearly half of all Americans.

As a result, time-consuming cleanup efforts are unfolding all across the country, with remediation for a single gas station sometimes topping $1 million. Leaks are such a huge liability that they've led to a high-stakes game of hot potato, where no one wants to pay for the mess -- not the gas station owners, not the insurance companies that provide coverage for tanks, not the oil companies that supply the fuel. In some states, polluters have shifted tens of millions of dollars in remediation costs onto taxpayers. Roughly 60,000 contaminated sites are still waiting to be cleaned up, according to the Environmental Protection Agency, or EPA -- and those are just the ones that have been found. Washington state has about 2,500 in line, one of the biggest backlogs in the country.

"The whole financial underpinnings of gas stations are starting to crumble."

Much of this pollution has been stagnant for decades. Forty years ago, steel storage tanks began corroding, setting off a slow-motion environmental disaster all over the United States. Leaks often weren't discovered until long after petroleum had poisoned the groundwater, when neighbors of gas stations began complaining that the water from their taps smelled like gasoline. In 1983, the EPA declared leaking tanks a serious threat to groundwater, and Congress soon stepped in with new regulations. One of the largest spills was in Brooklyn, where a 17 million-gallon pool of oil gradually collected beneath a Mobil gas station -- a larger spill than the Exxon Valdez disaster in 1989, when a tanker ran aground in Alaska and poured oil into Prince William Sound.

Fast-forward to today, and more than half a million leaks have been confirmed around the country. The Government Accountability Office estimated in 2007 that the total bill for cleanups would top $22 billion. Those old, decrepit storage tanks have left a legacy: overgrown, empty lots that real-estate developers don't want to touch. Of the roughly 450,000 brownfields in the country, nearly half are contaminated by petroleum, much of it coming from old gas stations.

As the contamination from these spills lingers, underground storage tanks are becoming a problem again as the next generation of tanks -- installed in a rush after the old steel ones started breaking -- begin nearing the end of their 30-year warranties, when there's broad consensus they are highly likely to leak. In Washington state, for instance, the average tank is about 29 years old. The tanks at the Arco station in North Seattle were replaced in 1990, soon after contamination was discovered, putting them a few years past the 30-year cutoff.

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