An explosion at a construction site off McLain Flats Road earlier this month occurred after natural gas collected in a crawl space under the kitchen, an official said Tuesday.
The origin of the explosion “was a static arc from a contractor’s finger in a natural gas rich atmosphere,” said Benjamin Smith, deputy fire marshal for the Aspen Fire Department.
“As for why there was natural gas released, that is still under investigation and will be reported when possible,” Smith said in an email Tuesday to The Aspen Times. “What I can tell you is that there was an electrician and plumber working in that space when the explosion happened.”
A static arc occurs when static electricity releases through an object to a grounding source, causing electrical current to run a short distance through the air, he said.
“In this case, the electrician was working in the crawl space and got close to a switch,” Smith said. “My hypothesis is that when he went to touch the switch, he caused a static arc on the metal plate switch.”
The large explosion about 2:30 p.m. Feb. 3 collapsed one of the floors of the 8,000- to 10,000-square-foot home under construction on Slalom Path, took down walls and blew windows out of frames, Aspen’s deputy fire chief, Jake Andersen, said at the time. Four people were taken to the hospital, and four others on scene were treated for less serious injuries.
Paramedics on scene found the most seriously injured man stuck under drywall and other debris on the unstable first floor. That man was later helicoptered to a Denver-area hospital. Two other workers were admitted to Aspen Valley Hospital, while a fourth man was treated at AVH and released.
The two most critically injured workers were in stable condition as of Tuesday, while all others injured were in good condition, Smith said.
Officials with the Occupational Safety and Health Administration in Denver are investigating the incident, said Chauntra Rideaux, an OSHA spokesman in Denver.
“More details will be available once OSHA is done investigating,” Rideaux said in an email.
A phone message left Tuesday for Brikor Associates Inc., the contractor building the home that exploded, was not returned.
The home is one of three under construction on Slalom Path that are all owned by Bob Hurst, vice chairman of New York-based Crestview Partners.
Read More: Natural gas, static electricity caused construction site explosion, Aspen fire