A lengthy federal investigation has blamed faulty gas venting equipment as the likely cause of a 2016 explosion that leveled a Silver Spring apartment building, killing seven people and injuring 68 others.
During a Tuesday meeting in Washington, a four-person National Transportation Safety Board panel outlined the history and probable cause of the explosion at the Flower Branch apartment complex, capping a nearly three-year investigation.
What remains unclear is when the pipe was disconnected, by whom and what caused the gas to ignite.
The disconnected piping bypassed a safety feature intended to ventilate gas from the basement to the outside, according to the report.
NTSB staff said Washington Gas, the Virginia-based company that provided services to the 14 apartments on Arliss Road, was responsible for maintaining the vent line that likely caused the explosion.
Board members did not indicate whether any charges or penalties would be brought against the company.
At 11:50 p.m. Aug. 10, 2016, a resident of the apartments noticed a gas smell as he was taking his trash to a dumpster. Less than a minute later, before he could call police, an explosion felt miles away rocked the three-story building.
Some residents were trapped under debris calling for help. One family trapped on the top floor of the partially-collapsed building dropped an infant from a window to safety in the arms of a stranger, according to testimony provided by investigators.
NTSB officials said the investigation took longer than anticipated because the building collapse, “compromised evidence that would have led to a quick resolution.”
“We know that … longer investigations can add to frustration on the part of survivors and families, during a time already marked by pain and loss,” said Robert Sumwalt, NTSB chairman. “But please understand that the goal of the NTSB safety investigation is to improve safety, to prevent the future accidents so that others will be spared a future pain and loss. Meeting this goal with confidence, it takes time.”
Officials said other “communication gaps,” some a year before the explosion, resulted in missed opportunities to detect and remedy the disconnected pipes.
Six times in the year leading up to the explosion, residents reported a gas smell in the apartment building to the management company, Kay Management, but each time, maintenance staff said they did not detect gas or attributed it to apartments being painted.
Representatives of Kay Management said in a statement Tuesday afternoon they are “deeply saddened” by the explosion and are working to install a memorial near new apartments currently under construction at the same site.
“While the NTSB’s conclusions and recommendations cannot make up for the loss of life, we hope others will learn from this tragic incident and take steps to prevent it from ever happening again,” the statement said.
On July 25, 2016, two weeks before the explosion, a resident – the same one who noticed a gas odor on the night of the blast – called 911 to report a gas odor in the apartment building, but Montgomery County firefighters did not detect the gas, according to the report.
Natural gas is odorless and a chemical is added to it so it has a noticeable smell that can signal a leak.
Nobody reported the incident to the apartment’s gas company.
“Had they been notified of the July 25th odor complaint Washington Gas would have had the opportunity to investigate further and potentially prevent the accident,” said Rachel Gunaratnam, the NTSB lead investigator.
Firefighters were unable to access the room in which the gas smell was originating because the lock had recently been changed and Kay Management didn’t replace the key stored on site for authorities. A 24-hour maintenance hotline provided by the management company could not be reached for assistance that day, investigators said.
“In my observation we missed a very good opportunity to possibly have stopped this whole thing,” said board member Bruce Landsberg.
Board members and investigators said throughout their probe, Washington Gas officials attempted to evade culpability and were resistant to proceedings.
“At times during this investigation, Washington Gas treated meetings and interviews more like a court room cross examination than a joint investigation geared at finding the cause of a tragic accident,” Montgomery County Fire Explosives Investigator Lt. William Olin wrote in testimony provided to the board. “I feel that Washington Gas overlooked testimony provided to the NTSB during field interviews and questioned the validity of the facts.”
In a 99-page report, Washington Gas officials said because preliminary reports in 2016 by the national Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) could not determine a conclusive cause of the blast, the national safety board should reach the same conclusion.
“It is worth noting that while the ATF suggests in its summary redacted report of September 23, 2016 that the NTSB investigation could develop facts leading to a different conclusion, the NTSB investigative findings, as further discussed in this report, serve only to strongly support the ATF conclusion that a probable cause for this accident is UNDETERMINED,” the Washington Gas report says.
NTSB members on Tuesday argued their investigation is more intensive and focuses on ways to prevent similar events in the future.
“This was a serious tragedy,” said board member Jennifer Homendy. “In the days and months that followed, Washington Gas should have been laser focused on the safety deficiencies that led to this incident and what could have been done to prevent it from occurring.”
In a statement after the hearing, Washington Gas officials said they disagree with the board’s findings.
“We have great respect for the NTSB and we know they worked diligently to find a probable cause of this tragedy,” the statement said. “As a participant in this investigation, we worked side by side with the NTSB to fully understand what transpired that night. However, we disagree with their findings as we don’t believe the evidence indicates failure of our equipment that night. We also do not believe the NTSB sufficiently investigated the other potential causes of the explosion.”
An earlier version of this story said Kay Management had declined comment. After the story published, the management company sent a statement. The story has also been updated to include a statement from Washington Gas, who previously could not be reached for comment.
Caitlynn Peetz can be reached at firstname.lastname@example.org