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Seismic Explosions

Fifty years ago, two gas-fueled explosions ripped through Reno, Nev., but new technologies make a similar scenario today unlikely.

by / October 26, 2007
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Feb. 5, 1957, began like every other day for Jerry Fenwick, who worked at his family's paint and art supply store in downtown Reno, Nev. Yet on this day, Fenwick decided not to check on his prize 1957 Dodge Custom Royal Lancer, which was being modified at the local repair shop a few blocks away, as he usually did on his lunch break.

The decision most likely saved his life. Fenwick's usual stroll would have put him at the corner of First and Sierra streets right around the time of a deadly blast.

Alerted by complaints of strong gas odor, a crew of five firefighters had converged on to the intersection, evacuating surrounding buildings. Moments later, at 1:03 p.m., two gas-fueled explosions 30 seconds apart shook downtown Reno, completely destroying two buildings, killing two people and injuring dozens. Fenwick, still at work two blocks away, said he had no injuries, and that most of those harmed were on the same block as the blast.

Though the explosions were at ground level, they were strong enough to register seismic reverberations equivalent to a 1.5-magnitude earthquake, according to the University of Nevada's Mackay School of Mines.

"I felt a terrible loud thump like something had been dropped," Fenwick said. "I turned around and saw the old-fashioned door jam lifted off the post three inches. That's when I knew something radically was wrong. I looked down the street and saw huge pieces of roof drifting down."

The blast was so strong it shattered windows in a block-and-a-half radius, said Jim Paterson, who at the time of the blast worked at Paterson's - one of the buildings that was completely demolished.

"The blast took the roof off the building where I worked and dumped it on the street," Paterson said.

Reno firefighter Bill Shinners was outside Paterson's when the blast hit; when he looked up, the sky was red. Shinners and other firefighters fought the fire for about 36 hours without any sleep. After the first seven hours, Shinners stole a needed break on top of the aerial fire ladder.

"I got up there to relax and started to shake uncontrollably," Shinners said. "I think I was in a state of shock."

The explosion was caused by a ruptured gas main that filled an undetermined area with gas before igniting. Damage from the blast was estimated to be more than $7 million, according to the Reno Gazette-Journal.  

 

Fast-Forward
Fifty years later, new technologies, added safety precautions for emergency responders, more stringent building codes and stricter gas line controls imposed by energy companies have lessened the chances for another gas-fueled explosion in Reno, said Marty Scheuerman, division chief of the Reno Fire Department and emergency manager of the city.

Today, firefighters' technological arsenal includes devices that detect the presence of flammable vapor in the air and lower and upper explosion limit of gases, which determine if a structure or area is safe from potential explosions, Scheuerman said. Firefighters also carry an assortment of equipment for plugging gas line leaks, and are trained on how to approach and contain pressure leaks.

Gas line maps and computerized building schematics have improved firefighters' ability to shut off potentially deadly gas lines if a leak is detected or before approaching a fire, Scheuerman said. Sierra Pacific Power, the local gas and electric company, also has extensive mapping systems of gas lines and excess flow valves that automatically shut gas flow off when a leak is detected.

Reno now has a large natural gas pipeline that flows from Canada and is equipped with infrared monitors that detect the presence or leakage of flammable vapor.  

Even with more advanced technology and mapping, however, another gas-fueled explosion isn't entirely improbable, especially in

mountainous areas, like Reno where the use of propane gas is prevalent.

"There's always a chance when there is a structure fire with a potential for gas leak, that it could ignite," Scheuerman said. "There's always potential, but I don't think the potential is as high as it was in 1957."

 

Forming Partnerships
About 30 miles west of Reno, the town of Truckee, Calif., has experienced its share of gas problems.

In 1989, a three-story building was leveled in downtown Truckee because a propane leak ignited, and in 2003, a large-scale propane gas leak lasted for several months, with an estimated 22,000 gallons of propane seeping into the ground. The gas didn't ignite, but a local school, businesses and homes in the area were evacuated for weeks at a time. Donner Pass Road, a major thoroughfare, was also closed while firefighters and energy officials attempted to locate the leak.

The gas leak was finally pinpointed to Amerigas, a company that provides propane gas to the area. The leak was caused by a damaged gas line whose coating had been scraped off and was weakened by corrosion, said Gene Welch, public safety and information officer for the Truckee Fire Department. The area of the leak was covered by asphalt, so Welch said, the gas traveled a longer distance before being diffused in the air.

"It's not uncommon," he said, "because of the territory we live in and conditions of the area for snow to build up and damage gas lines."

When a leak is detected, fire crews first evacuate a home or building, and then shut off all power to reduce the number of ignition sources, Welch said, adding that the safest and fastest way to handle a propane leak is to cut off the source and let the propane dissipate naturally.

Homes in Truckee powered by natural gas are required to have a "two-state regulator" that helps prevent gas leaks. In areas with freezing temperatures, regulators often freeze, requiring two regulators in propane valves. Homes are also required to have two propane shut-off valves: one inside the house and one outside, near the propane tank.

Strong partnerships between gas companies and emergency responders can help avoid such disasters. Both the Reno and Truckee fire departments work closely with gas companies when a gas leak occur and share information about gas lines. When a leak occurs, agencies work together to find the leak and prevent another devastating blast like the one that occurred 50 years ago in Reno.

"Our techniques are better, our equipment is better, our ability to detect gas is better," Scheuerman said, "and quality of gas mains are a lot better."

Chandler Harris Contributing Writer