MORGANTOWN, W.Va. (AP) -- State regulators say a worker was killed Friday morning in an explosion at an EQT natural gas well pad near Flemington in rural Taylor County.
Department of Environmental Protection spokeswoman Kathy Cosco said the unidentified victim was working alone at the time.
The man was attempting to transfer briny wastewater from a tank into a truck, she said. What sparked the explosion is unclear and will be the focus of the state's investigation, already under way.
Drillers inject massive volumes of water, sand and chemicals to hydraulically fracture, or frack, the rock in which gas deposits are trapped. The gas then flows up for collection, as does the brine. The DEP says some of the chemicals in the brine could be flammable.
Linda Robertson, a spokeswoman for Pittsburgh-based EQT, said the victim was an employee of a gas company contractor, but she did not identify either that company or the worker. Robertson said those details were being withheld pending notification of his relatives.
"Details are very limited," she said in an email, "but what is known is that the incident was not related to drilling, as it occurred on a producing well site."
It appears the contractor was onsite to check fluid levels on water storage tanks, she said. The well produces dry gas and does not contain any condensate.
"The safety and security of EQT employees and contractors is a core value," Robertson said, "and it's a sad day when we lose anyone within our community."
Cosco said the DEP wasn't sure what time the blast happened because no other workers were present.
But Mary K. Singleton, who lives about a mile away, said her house shook at 6:45 a.m.
"I heard an explosion but I didn't know what it was. You never know around here," she told The Associated Press.
"I got up and made sure the house was all right, but couldn't see anything. I didn't know what's going on," she said. "I asked my husband, 'you suppose it was a meteor?'"
Corky DeMarco, executive director of the West Virginia Oil and Natural Gas Association, said EQT is calling the fatality an "industrial accident," not an explosion, and he's never heard of brine exploding.
"To the best of my knowledge, brine is not flammable," he said. Accidents involving brine are typically spills, he said, "so that, I don't understand."
Brine is 99.5 percent water and sand, and drillers typically do not add potentially flammable chemicals, DeMarco said. What flows back up from a well is mostly salty water, and any chemicals are diluted.
"Contrary to what some people like to say," he said, "we don't use diesel fuel or any of those kinds of additives that would be flammable."
But David McMahon of the West Virginia Surface Owners' Rights Organization said the fracking fluid often contains volatile organic compounds, "so brine tanks can have vapors of these that are surely explosive."
Many people who live near well pads are worried about those compounds being vented into the atmosphere and harming air quality, he said.
Though the development of the Marcellus shale field underlying West Virginia has been booming, the DEP says there have been only five fatal accidents since 2008. Three have involved well sites, while two involved access road activities.
EQT is one of the largest exploration and production companies in the Appalachian shale gas fields, with drilling rights to more than 3.5 million acres in West Virginia, Pennsylvania, Kentucky and Virginia.
EQT's website says it has proven reserves of more than 32 trillion cubic feet equivalent, and it's grown those reserves by more than 120 percent over the past five years.
EQT says it plans to spend $1 billion in well development this year.
Associated Press writer John Raby contributed from Charleston.