April 16--Before the West Fertilizer plant explosion a year ago, not much thought had been given to the devastating effects of such a catastrophe.
The blast, which was equivalent to 15,000 to 20,000 pounds of TNT, damaged 350 homes, destroying 130 and leaving 51 with major damage. The explosion killed 15 and injured at least 200.
So it's not surprising that University of North Texas professor Zhenhua Huang, an assistant professor of construction engineering technology, felt it was urgent that he study the deadly blast's effect on nearby buildings and share his findings.
"I think I had a responsibility to do this," Huang said.
Financed by a $10,000 National Science Foundation grant, Huang arrived in West six days after the explosion. He began surveying the most heavily damaged neighborhoods, in the north of town closest to the fertilizer plant.
The goal was to study how various buildings were impacted by the explosion and present those findings to engineers and communities. Huang hopes his work leads to better zoning laws and building codes to prevent a repeat of what happened in West.
"It can be used by local governments and developers," Huang said. "For example, if there is an existing facility like this fertilizer plant, builders and developers need to think about how far away should I build for my community to be safe. If someone is building near one of these fertilizer plants, then put it further away so these communities should be in a safe zone."
West had no building codes
Huang's study comes while the state fire marshal is recommending that 46 facilities storing ammonium nitrate in Texas be required to make structural improvements that would help prevent another deadly explosion.
On Monday, state Fire Marshal Chris Connealy proposed to the House Homeland Security and Public Safety Committee that these facilities should have three years to install sprinklers or retrofit buildings with noncombustible materials.
But at the the same meeting Monday in Austin, the industry resisted further regulation.
"It's a question that keeps coming up from a lot of folks -- 'You're just going to put us out of business,' " said state Rep. Dan Flynn, R-Van.
Whether there are more regulations or not, Huang said, local officials should push these facilities to create concrete barriers or even buy out buildings closest to the the facility.
In cities where these facilities are in the middle of town, Huang said, building some type of barrier should still be considered.
"If you want to build a protection wall, it doesn't have to be circular in shape," Huang said. "You can still have protection. But what you would like to do is draw a circle and move everybody out of that closest zone."
West Mayor Tommy Muska said the city has seen 64 new homes go up with 25 already occupied since the blast. The rest are in various stages of construction, he said.
Before the explosion, West didn't have building codes and new homes weren't inspected.
"We worked hard after the explosion to establish building codes and we are still working on commercial building codes," Muska said. "At least now, our new homes get inspected by an outside inspector."
Muska has floated the controversial idea of rebuilding the fertilizer plant because it served a need in the agricultural community. For now, he said many residents oppose the idea.
"That's a hard pill to swallow for a lot of people and I'm not going to fast-track it," he said.
Even if a new plant were built, Muska said, he would want to make sure West has some sort of control. When the explosion occurred, West Fertilizer Co. was just outside the city limits.
"If it does come back in some area around West, we need to incorporate it into the city limits," Muska said. "Then we need to make sure we have a buffer zone around it and prohibit any residential buildings and keep it in an industrial setting where it needs to be."
Buffer zone protections
The idea of a buffer zone dovetails with Huang's research.
He has identified danger zones: Within 550 feet of the plant is the destructive zone. Between 500 and 750 feet, is the hazardous damage area.
In those zones, people were in danger of being killed or injured.
"I think this type of facility should be far away from any residential buildings," Huang said. "If they use the same amount of fertilizers, it should at least 750 feet from any residential structure."
From 750 feet to 1,200 feet, Huang said the damage was for the most part repairable.
From 1,200 to 3,000 feet, most homes should only have minor damage.
The one exception to these guidelines were the three West school district schools, which were outside the most serious zone of destruction. The distances of the schools to the epicenter are 1,008 feet, 1,956 feet and 2,714 feet.
"This is because of long-span engineering building," Huang said. "Those are very vulnerable to shock waves and overpressure because the surface area is very big. The total force on this type of structure is much higher. In the gymnasium, the roof is completely collapsed."
Huang said the building's designers weren't expecting such forces.
"Engineers didn't expect this type of explosion could happen," he said. "What we should do as engineers is to design a safer community and a safer facility."
Besides presenting his report to engineers and the National Science Foundation, Huang said he will provide a copy to the cities of Denton, site of UNT, and West.
He also plans to create an interpretative exhibit for the Children's Museum in Dallas that will help visitors understand the destructive power of explosions.
"It will be a map with different zones where children can click and touch it like an iPad," Huang said. "They can touch a house location and the damage will pop up."
This report includes material from The Associated Press.
Bill Hanna, 817-390-7698 Twitter: @fwhanna
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