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By Stephen Lee
Jan. 26 — Gaps in federal safety laws likely facilitated the 2013 explosion and fire at West Fertilizer in West, Texas, according to a preliminary report released by the U.S. Chemical Safety and Hazard Investigation Board Jan. 25.
One key gap was found in the Occupational Safety and Health Administration's explosives and blasting agents standard, which allows companies to store ammonium nitrate (AN) in wooden bins, provided the bins are protected against the impregnation of ammonium nitrate.
However, the rule isn't specific enough—for example, it doesn't define the word “impregnation”—leaving users “to decide appropriate safety measures without proper instruction,” the CSB said.
Moreover, wooden bins aren't recommended in other countries, according to the report.
West Fertilizer stored its AN in three plywood bins, although they hadn't been treated with coated or clad materials. The CSB found that “such construction likely facilitated the fire's spread between storage bins.”
Twelve emergency responders and three members of the public died when a stockpile of AN detonated at West's facility on April 17, 2013. Local hospitals treated 260 patients following the blast, and nearby buildings were flattened (43 OSHR 382, 4/25/13).
The report also noted that, at the time of the incident, West qualified under OSHA's “retail exemption” in the process safety management (PSM) standard, meaning the company didn't have to comply with the rule because more than half of its income was derived from sales to direct end users.
Had the PSM rule applied to West, the company would have had to conduct a process hazard analysis that, among other things, would have identified the close proximity of the facility's AN storage warehouse and its anhydrous ammonia storage tanks. That knowledge, in turn, theoretically would have led the company to implement additional safeguards, the CSB said.
The 2013 explosion damaged West's anhydrous ammonia tanks, the CSB said. Had more force been applied to the tanks, the ammonia could have been released into the community.
OSHA won't cite storage facilities for failing to comply with its recent reinterpretation of a process safety management retail exemption through Sept. 30, 2016, the agency said in a Dec. 23 memo. That directive follows passage of legislative language, embedded in the fiscal year 2016 appropriations omnibus, to delay implementation of the reinterpretation until OSHA completes traditional rulemaking procedures on the change (46 OSHR 16, 1/7/16).
The report further called on OSHA to launch a regional emphasis program in parts of the country where fertilizer storage facilities are common. Such a program would include a certain number of annual inspections per year, the CSB said.
The precise cause of the explosion may never be known because AN behaves so unpredictably, according to the 262-page report, which CSB members will vote on at a public meeting in Waco, Texas, on Jan. 28.
However, the report did identify two probable contributing factors: the contamination of the AN with materials that served as fuel and the nature of the heat buildup and ventilation of the storage space. The report also contains three specific scenarios describing how the detonation may have happened.
Several gaps may have also contributed to the 12 emergency responders' deaths, the report concluded. The personnel didn't establish an effective incident command system, hadn't been adequately trained in the handling of hazardous materials, didn't know enough about the hazards of AN and lacked situational awareness on the scene, according to the report.
To make matters worse, much of the technical information about AN that was available to the firefighters was “limited and conflicting,” the report said.
At the time of the blast, West held between 40 to 60 tons of AN on site. Some 30 tons detonated. Nearly half of the 80 facilities across Texas storing more than 5 tons of AN are located within half a mile of a school, hospital or nursing home, the CSB said.
The board's report also contained recommendations calling on OSHA to either add fertilizer-grade AN to the PSM rule's list of highly hazardous chemicals, toxics and reactives, or to revise its explosives and blasting agents standard to prohibit the use of combustible materials for AN facilities and bins and also to require automatic fire sprinkler systems for indoor AN storage areas.
Other recommendations went to the Environmental Protection Agency, the Federal Emergency Management Agency and various Texas state agencies.
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