As emergency workers address the aftermath of an EF-5 tornado that struck Moore, Okla., on May 20, lawmakers and industry members are grappling with whether regions vulnerable to EF-4 and EF-5 events should require safe rooms in schools and other non-residential facilities.
The Moore tornado, which packed winds in excess of 200 mph, resulted in 24 fatalities, seven of whom were students at an elementary school without a safe room. Schools with safe rooms in Moore reported no fatalities.
On May 21, Oklahoma State Rep. Joe Dorman (D) requested House staff to draft a bill for a $500-million bond issue to fund the construction of safe rooms in state public schools. Because the legislative session concluded on May 24, lawmakers won't have an opportunity to address the issue until early 2014. "In the meantime, we'll request interim studies to get designers and educators involved," says Dorman. "Hopefully, concern won't diminish with time."
The Oklahoma Dept. of Emergency Management reports that more than 100 schools in the state currently contain safe rooms. Like other Tornado Alley states, Oklahoma allows jurisdictions to decide whether safe rooms should be required in residential and non-residential structures.
"Even now, there's a lot of talk coming out of Oklahoma City that they're too expensive to build or don't work if they're sited above grade, and that's simply not the case," says Brian Orr, principal with Springfield, Mo.-based engineer Toth and Associates, which is consulting with Federal Emergency Management Administration officials in Moore. "We've been involved in installations that added as little as $30,000 to an 8,000-sq-ft facility." Depending on region and site conditions, costs can vary from $90 to $160 per sq ft, he says.
Safe rooms in place in Oklahoma schools are typically gymnasiums or cafeterias that conform to FEMA Standard P-361, which specifies hardened structures capable of withstanding debris driven by 250-mph winds. "Under those conditions, winds exert pressures of 180 to 230 pounds per sq ft on a safe-room wall," says Orr. Assemblies typically consist of 12-in.-thick to 14-in.-thick insulated concrete or concrete block, he notes. "Even masonry will work on shorter structures," Orr adds.
Devastated by an EF-5 tornado in 2011, the city of Joplin, Mo., does not require safe rooms in schools, though the Joplin School District elected to include them in both existing and new structures, including those under construction to replace the facilities destroyed in 2011.
"There was discussion of mandating them for schools and other non-residential facilities, but, frankly, many of the engineers we consulted with weren't convinced they would provide adequate protection against 200-mph winds," says Joplin's assistant city manager, Sam Anselm.