By Ken Robinson
FireRescue1 Associate Editor
GRETNA, Md. — Ineffective ventilation techniques and insufficient equipment and training contributed to the injuries of eight firefighters in a strip mall explosion, according to investigators.
Two captains, a lieutenant and five other firefighters were responding to a natural gas leak inside a business May 7 last year when the explosion occurred.
Firefighters had already evacuated civilians from seven businesses in the area when they noticed fire along the roof line of a building and an electric meter on fire, moments before the blast.
The blast threw two firefighters out of the building and many other firefighters near the front of the structure were knocked down and struck by debris, a NIOSH report released Wednesday said
A mayday was issued and injured personnel were transported to local hospitals via ambulance after all crew members were accounted for.
The injuries ranged from third degree burns to an ankle sprain.
According to the report, an earlier explosion could have happened because firefighters had set up a positive pressure ventilation fan in front of one of the store front doors, but was avoided because the fan did not operate properly.
In the absence of fire, “firefighters should never ventilate structures containing natural gas while personnel are inside,” the report said.
“Firefighters should not open windows until they are certain the gas supply has been shut off and ignition sources have been eliminated because gas can ignite as it passes through the explosive range.”
Investigators also found that during the response, firefighters located an electrical panel and began to turn off individual breakers, instead of the main disconnect.
Instead, the report recommends having utility companies immediately cut external power to structures when gas leaks are suspected, saying “any breaker could have the potential to spark, causing an explosion if the requisite concentration of gas was present.”
Gas monitoring equipment did not go into alarm during the incident, the report said, pointing out that such devices can malfunction due to a dirty filter, an attached calibration adapter, or being turned on in a highly concentrated gas environment.
The fire department had been unable to maintain and train on proper use of the equipment due to funding constraints, the report said.
Several firefighters interviewed by investigators reported they were unaware of the fire department’s SOG for incidents involving flammable gas and officers did not know about revisions made two months before the explosion.