Exxon Mobil Corp. said today that 4,200 gallons of "produced water" were spilled from a Pennsylvania natural gas well site of company subsidiary XTO Energy in Pennsylvania as a result of a valve being left open on a storage tank. The Pennsylvania Department of Environmental Protection (DEP) said the dirty water polluted a nearby stream and a spring.
Rachael Moore, a spokeswoman for Irving-based Exxon Mobil, said in an e-mail response to Star-Telegram questions that Fort Worth-based XTO "is taking steps to avoid this...happening again in the future."
Produced water is coughed up from deep underground along with gas produced from a well. The spill was of produced water, rather than from "hydraulic fracturing fluid" used in fracturing wells, as stated in a prior DEP news release, Moore said. Produced water is typically polluted, salty water that isn't safe to drink and may contain potentially toxic chemicals and metals.
DEP spokesman Daniel Spadoni told the Star-Telegram today that XTO originally estimated the spill at more than 13,000 gallons and also previously told the agency that the spilled water was "frack flowback fluid," the mix of water, sand and chemicals used in hydraulic fracturing of wells.
Moore said XTO determined the spill was 4,200 gallons after "a thorough review of inventory records" and that the 13,000-plus figure was an earlier "worst-case estimate" that proved inaccurate.
Spadoni said XTO probably will be sent a notice early next week, outlining what regulations it violated and the potential penalties.
The spill occurred at XTO's "Marquardt site" in Lycoming County in north central Pennsylvania (not southwest Pennsylvania, as the Barnett Shale Blog said in a prior post).
--Jack Z. Smith
See the full story in Thursday's Star-Telegram.