Public Service Commission Investigating Washington Gas Over Flower Branch Apartment Explosion

Public Service Commission Investigating Washington Gas Over Flower Branch Apartment Explosion

PSC questions whether company properly utilized funds to replace equipment

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A photo of the aftermath of a 2016 explosion at the Flower Branch Apartments in Silver Spring.

Photo via NTSB

The Maryland Public Service Commission has launched an investigation into whether Washington Gas properly utilized funds budgeted in 2003 to replace some equipment, 13 years before the same type of equipment contributed to a deadly apartment complex explosion.

In 2016, an explosion at the Flower Branch Apartments in Silver Spring killed seven people and injured nearly 70 others. This year, after a lengthy review, the National Transportation Safety Board (NTSB) determined the explosion was caused by the failure of a mercury service regulator with an unconnected vent line that allowed natural gas into the meter room where it ignited. The board said the gas company was responsible for ensuring the vent line was connected.

The regulators reduce the pressure of natural gas in piping to the level used in homes. The mercury seal is intended to act as a “relief valve” and serves as “overpressure protection,” according to Washington Gas documents.

The NTSB issued a list of recommendations to various local, state and federal agencies as a result of its investigation, but most of the recommendations fell to Washington Gas, including to replace all mercury gas regulators.

The NTSB also recommended Washington Gas procedures be updated to mandate that field technicians verify vent lines are connected and functioning properly after testing the equipment.

In a statement in April, Washington Gas officials disagreed with the findings of the NTSB investigation and indicated there are thousands of mercury regulators still in use in Maryland, Virginia and Washington, D.C.

A spokesman for Washington Gas said in a statement the company had received the Public Service Commission’s order and was “preparing a response” to be submitted to the commission in a “timely manner.”

In 2003, Washington Gas pledged to replace nearly 67,000 mercury regulators within 10 years, according to a Public Service Commission order filed Thursday.

The commission ordered Washington Gas officials to provide a formal update within 30 days about the status of its mercury regulator replacement plan and a written response to the findings of the NTSB investigation.

In its order, the Public Service Commission directed Washington Gas to explain “why the Commission should not impose a civil penalty” for not replacing the regulators and for “failing to use funds collected from ratepayers and approved for” the project.

The new filing shows the Public Service Commission in 2003 approved $654,000 to be used for the replacement program.

The commission plans to investigate whether Washington Gas exercised “reasonable care to protect the public safety,” according to the order.

A spokesperson for the Public Service Commission said, pursuant to state law, Washington Gas could be fined $25,000 per violation, per day.

In its final report, the NTSB directed Washington Gas to audit where its remaining mercury regulators are and establish a schedule for the replacement of the regulators, “giving highest priority” to those located inside multi-family complexes.

The Public Service Commission also asked Washington Gas to provide a detailed report about how the company intends to comply with those recommendations.

In April, when the NTSB report was issued, Washington Gas issued a statement disagreeing with most of 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.”

The statement also said the company was “reviewing closely” the board’s recommendation about the removal of mercury regulators, but said the equipment is “reliable and safe.” The statement said Washington Gas has been “systemically replacing” mercury regulators while conducting other work, but it does not say how many of the regulators remain in use.

“Our focus in replacing these regulators is for environmental— not operational — reasons,” the statement said. “We will work with our regulatory commissions to determine an appropriate timeline to complete the transition from mercury regulators.”

During its final hearing on the matter, NTSB board members and investigators said Washington Gas officials attempted to evade culpability and were resistant to its investigation.

Montgomery County officials called on the company to refocus its efforts on preventing future tragedies.

“Instead of denying responsibility for the explosion, Washington Gas needs to move quickly to implement the recommendations made by the NTSB,” Montgomery County Council President Nancy Navarro said in a statement in April.

Caitlynn Peetz can be reached at

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