"Injection wells used to dispose of the nation's most toxic waste are showing increasing signs of stress as regulatory oversight falls short and scientific assumptions prove flawed."

"On a cold, overcast afternoon in January 2003, two tanker trucks backed up to an injection well site in a pasture outside Rosharon, Texas. There, under a steel shed, they began to unload thousands of gallons of wastewater for burial deep beneath the earth.

The waste -- the byproduct of oil and gas drilling -- was described in regulatory documents as a benign mixture of salt and water. But as the liquid rushed from the trucks, it released a billowing vapor of far more volatile materials, including benzene and other flammable hydrocarbons.

 The truck engines, left to idle by their drivers, sucked the fumes from the air, revving into a high-pitched whine. Before anyone could react, one of the trucks backfired, releasing a spark that ignited the invisible cloud.

Fifteen-foot-high flames enveloped the steel shed and tankers. Two workers died, and four were rushed to the hospital with burns over much of their bodies. A third worker died six weeks later."

Abrahm Lustgarten reports for ProPublica September 20, 2012. [2]