Outside Rosharon, Texas on January 2003, two tanker trucks backed up to an injection well site.  There, under a steel shed, they began to unload thousands of gallons of wastewater for burial deep beneath the earth. The byproduct of oil and gas drilling is described in regulatory documents as a benign mixture of salt and water, useless and considered waste. The liquid overflow from the truck released billowing vapors of far volatile materials, including benzene and other flammable hydrocarbons.  The trucks engines were left idling by their drivers and before anyone could react, one of the trucks backfired, releasing a spark that ignited the invisible cloud.