Exxon discharged the water from waste tanks at the Pennsylvania well in 2010, according to a statement on the website of Pennsylvania’s attorney general. The pollution was found during an unannounced visit by the state’s Department of Environmental Protection. The inspectors discovered a plug removed from a tank, allowing the wastewater to run onto the ground, polluting a nearby stream. Exxon was ordered to remove 3,000 tons of soil to clean up the area. Wastewater discharged from natural-gas wells can contain chlorides, barium, strontium and aluminum, the attorney general’s statement showed. This is pretty despicable. How can we make sure it doesn't happen again?