The natural gas explosion that destroyed a house in Centreville last month and forced dozens of others to be evacuated occurred hours after Washington Gas identified a critical leak in the neighborhood, an initial investigatory report says.
A service technician from the utility, which has multiple gas lines in the area, found a “grade 1” leak outside a home on Belle Plains Drive around 12:30 p.m. on Feb. 15 after the resident reported a “gas odor” about two hours earlier, according to the National Transportation Safety Board (NTSB).
Crews called to address the leak were still working on repairs around 9:48 p.m., when a nearby house in the 14300 block of Quail Pond Court in the Belle Pond Farm neighborhood exploded into flames, the NTSB says.
Released yesterday (Monday), the NTSB’s preliminary report offers the most concrete timeline yet of the lead-up to and immediate aftermath of the explosion, which injured two people, damaged several other houses and led 46 homes to be evacuated by the Fairfax County Fire and Rescue Department (FCFRD).
According to the report, a “grade 1” gas leak like the one found near the exterior of the Belle Plains Drive house “requires immediate action.” Washington Gas is required by the D.C. Public Service Commission to classify every leak on a scale of 1 to 3, with one being a hazardous incident that “presents immediate danger and requires continuous, immediate action until the area is secure.”
However, the neighborhood wasn’t evacuated until after the house exploded, and the utility didn’t shut off natural gas service to the area until 12:40 a.m. on Feb. 16, the report says.
Some residents reported seeing Washington crews working in the neighborhood since the morning of Feb. 15, but there’s no indication they were alerted to the potential safety risk.
According to the NTSB report, which refers to the natural gas provider by its parent company, AltaGas, Washington Gas’ 6-inch underground gas main serving the area had a pressure of 55 pounds per square inch at the time of the explosion, below the 60-pounds-per-square-inch maximum allowed:
Just east of the accident home, the main ran underneath three gas transmission lines operated by Williams/Transco. After the explosion, local and utility emergency responders detected subsurface natural gas near where the AltaGas main crossed underneath the Williams/Transco transmission lines (in the transmission line right-of-way) and in the yards of homes along Belle Plains Drive and Quail Pond Court. Gas was also detected inside several homes.
The NTSB oversaw testing of the gas main along Quail Pond Court starting on Feb. 17 that confirmed there was a leak, since the pipe was unable to hold pressure.
The source of the leak was finally located on Feb. 22 near the corner of Quail Pond Court and Belle Plains Drive.
After Washington Gas didn’t detect any additional leaks, residents were gradually allowed to return home, and the FCFRD officially lifted its evacuation order on Feb. 24.
Washington Gas didn’t comment on details of the preliminary report but said it’s continuing to cooperate with the investigation:
We appreciate the National Transportation Safety Board’s work and the release of its preliminary report regarding the incident on February 15 in Centreville, Va. We continue to cooperate fully with the NTSB and all relevant authorities as they complete their independent investigation.
The safety of our customers, employees, and the communities we serve remains our highest priority. We will continue to work directly with affected customers and carry out a comprehensive safety monitoring plan in the area.
In an update sent to affected customers last Friday (March 13), the utility said it has shifted to the second phase of a multi-phase monitoring and leak detection plan, as of March 7, which involves teams conducting daily leak surveys for at least two weeks.
“Please know that Washington Gas will continue to closely evaluate all survey results,” the company said. “If conditions change and data indicates that additional monitoring is needed, we are prepared to increase the frequency or scope of our work.”
Crews have completed repairs to sections of road that were excavated in order to find and address the gas leak, though it could take months for paving to be finished, depending on the weather.
Washington Gas has partnered with the mental health provider Spring Health to provide free, 24/7 access to its Crisis Support Line until April 2 for any community members experiencing stress, anxiety or other challenges.
“To access this resource, call 1-855-629-0554 and press 2 to reach a licensed clinician, who will answer within 60 seconds,” the utility said.
The company is also continuing to reimburse residents for any hotel expenses they accrued during the evacuation. The deadline to submit receipts is March 31.
The NTSB’s investigation into the explosion is still ongoing, with a final report identifying the cause of the leak, contributing factors and safety recommendations potentially taking another one or two years to complete.
