Colorado regulators have found no sign of natural gas leaks after a fatal explosion at a home near a gas well, but they are still running tests, officials said Thursday.
Two people died and a third was badly burned when the house exploded on April 17 in Firestone, 30 miles (48 kilometers) north of Denver. The house was within 200 feet (60 meters) of a well producing mostly gas and some oil.
State and local fire officials stressed they do not know what caused the explosion but the well is part of the investigation.
Matt Lepore, director of the Colorado Oil and Gas Conservation Commission which regulates the industry, declined comment on whether any evidence indicates a possible link between the well and the explosion.
Neighbors told the Longmont Times-Call the two men who died were working on a water heater in the home's basement when the blast happened. Investigators are looking into those reports but have not confirmed them, said Summer Campos, a spokeswoman for the Frederick-Firestone fire department.
Air sampling after the explosion found no traces of escaped gas in the neighborhood, but examinations of soil samples are planned to determine whether the soil had evidence of gas in it, Lepore said.
"Based on all the investigations to date, (the commission) believes there is no immediate threat to the environment or public safety associated with oil and gas operations in the neighborhood," Lepore said.
The possibility that a gas well contributed to the explosion has brought closer scrutiny to the incident. The proximity of wells to homes and schools has long been a contentious issue in Colorado, where fast-growing towns sometimes overlap with oil and gas fields.
Lepore said the gas well was drilled in 1993 and the nearby homes, including the one that exploded, were built later.
The state regulates how far new wells must be from homes and schools, but local governments control how close new homes can be built to existing wells. Firestone Town Manager Bruce Nickerson did not immediately return a phone call seeking comment.
Natural gas wells caused two house explosions in Colorado in 2007 and in 2005, Lepore said.
In one of the cases, investigators believe gas seeped from a coal seam into an old well and then into a trailer home, where it exploded. In the other case, gas seeped out of an improperly plugged well and destroyed a house under construction.
Anadarko Petroleum, which operated the Firestone well, shut it down after the explosion. State records show the well was last inspected in 2014, and received a "satisfactory" rating.
The company also began shutting down and inspecting 3,000 similar wells in Colorado as a precaution.
Anadarko said it will lose the equivalent of 13,000 barrels of oil a day while the wells are turned off. A barrel is 42 gallons (151 liters). The company declined to disclose the estimated value of the product.
Lepore said shutting down the wells was Anadarko's decision, not a state order.
All the wells being shut down are older vertical wells, like the one in Firestone, Anadarko said. Newer technology allows rigs to drill vertically and then horizontally tap oil or gas.
Officials in nearby Boulder County asked energy companies Thursday to shut down vertical wells in that county until their safety could be assured. It was not immediately known whether any operators complied.
Once the investigation into the Firestone explosion is complete, regulators will decide whether to order other energy companies to take any action, he said.
The blast killed Mark Martinez and Joseph William Irwin III. Erin Martinez, who was married to Mark Martinez, was badly burned. Irwin was her brother.
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