Deadly Silver Spring Apartment Blast Caused By Failed Gas Vent, Investigator Concludes

An explosion that killed seven people at a Silver Spring apartment complex in 2016 was caused by a failed gas vent, a federal investigator has determined. 

The National Transportation Safety Board Tuesday released the findings of its report on the Aug. 10, 2016, incident, detailing multiple failures that led to the explosion at the Flower Branch Apartments, the Washington Post reports.  

The explosion, which occurred at 11:51 that night, destroyed the buildings at 8701 and 8703 Arliss St. and caused over $1M in damage, according to the report. Seven residents died as a result of the explosion, 65 were hospitalized and over 100 were displaced. 

The report attributed the explosion to a mercury service regulator with an unconnected vent line that allowed gas to accumulate in the meter room, though it did not determine what caused it to ignite. Washington Gas owned the vent and was responsible for it, NTSB Investigator Rachel Gunaratnam said, according to the Post. 

Washington Gas released a written statement Tuesday pushing back against the NTSB report. While it said it respects the agency and participated fully in the investigation, the company did not accept the NTSB's findings. 

"We disagree with their findings as we don't believe the evidence indicates a failure of our equipment that night," Washington Gas CEO Adrian Chapman said in the statement. "We also do not believe the NTSB sufficiently investigated the other potential causes of the explosion." 

Chapman also responded to the NTSB's recommendation that Washington Gas replace mercury service regulators throughout its network. It said it has been systematically replacing the regulators for environmental reasons, but it maintained that they are safe and reliable. 

The NTSB also detailed errors on the part of Kay Management, the company that manages the buildings. It said Kay did not notify Washington Gas about six instances of residents reporting a natural gas smell, according to the Post.

Additionally, firefighters responding to a 9-1-1 call about a gas odor were reportedly unable to access the meter room because Kay had changed the lock and not provided a new key to the fire department. The firefighters did not smell gas outside the meter room and also failed to notify Washington Gas about the incident, Gunaratnam said. 

"We appreciate the NTSB’s thorough review of the incident and accept their conclusion about the probable cause of the explosion, that there was a gas regulator failure and a disconnected vent pipe — equipment not owned or maintained by Flower Branch Apartments," Kay Apartment Communities President Clark Melillo said in a statement. 

Kay Apartment Communities in March 2018 began construction on two apartment buildings totaling 27 units to replace the two buildings lost in the explosion. It said the project would be completed this spring.