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Investigators were working Tuesday to pinpoint the gas leak behind a Centreville house explosion that injured two people and displaced dozens of families, with officials warning that the evacuation zone could expand if a large transmission line is involved.
The house in the 14300 block of Quail Pond Court, near Buggy Whip Drive, exploded around 9:45 p.m. Sunday, Feb. 15. Neighbors reported smelling gas before the blast.
Two people were injured, including one person inside the house. Neither suffered life-threatening injuries.
Fairfax County Fire and Rescue remained at the scene Tuesday to support utility crews and the National Transportation Safety Board, which is leading the investigation.
Washington Gas was excavating at several nearby locations to determine which line may be leaking. At least five transmission lines operated by Washington Gas and Williams Pipeline Corporation run through the area.
Assistant Fire Chief Eric Craven said the lines overlap and cross one another, requiring crews to isolate and examine them methodically instead of allowing multiple utilities to dig simultaneously.
The pipelines range from about 2 inches to 42 inches in diameter. Craven said the existing evacuation distance should be sufficient if the leak involves a smaller 2-inch or 6-inch line. If investigators trace it to a larger pipeline, however, evacuations could extend as far as a quarter-mile from the suspected leak.
As of Tuesday afternoon, fire officials had declared 46 houses unsafe to occupy, while 82 homes were without natural gas service. Roads around the explosion site also remained closed.
Firefighters continued going door to door to measure gas concentrations. Craven said some homes showed low readings while others registered none, with overall levels declining as utilities shut down sections of the gas system.
Officials believe nearly all gas service in the affected area has been eliminated. Craven said remaining odors or readings may be gas rising through the soil from before the explosion.
The size and location of the leaking line will help determine when residents can return. Craven estimated the evacuation could continue for another 24 to 72 hours while crews identify the line, expose and repair it, test the system and restore service.
Firefighters were escorting residents into evacuated homes to retrieve essential belongings after testing indoor gas levels. One Buggy Whip Drive resident said she learned Tuesday that her household had to leave after initially believing its location across the road might keep it outside the evacuation area.
The NTSB, which oversees pipeline safety, said investigators were beginning tests of pipeline infrastructure with local partners to identify the leak’s potential source. The agency also planned interviews with local authorities as it works to determine the probable cause and identify possible safety improvements.
NTSB representatives were expected to attend a Tuesday night town hall for residents and join Fairfax County Fire and Rescue at a Wednesday afternoon news conference. About 100 residents attended an earlier meeting with fire officials and gas-company leaders.