Tuesday, November 13, 2007

Ammonium Nitrate Rules Tightened

Spencer S. Hsu in his Washington Post article, DHS Relaxes Chemical Plant Storage Rules, parrots the view of many liberal commentators that DHS has reduced the effectiveness of the requirements of the CFATS regulations with the new limits set by the revised Appendix A to 6 CFR part 27. While he barely mentions that political pressure by Democratic Senators was responsible for the whole sale gutting of the propane provisions he implies that changes to the Ammonium Nitrate STQ will enable future attacks like those in Oklahoma City and the first Trade Center attack. This article shows that he has failed to read the preamble to the Final Rule on Appendix A.


The proposed Appendix A treated ammonium nitrate as a unitary chemical, an explosive. There are actually two different chemicals generally found in commerce under the generic name of ammonium nitrate. The most common form of ammonium nitrate is that widely used as a fertilizer and then there is the commercial explosive ammonium nitrate. The difference between the two is generally the amount of organic material added to ammonium nitrate to make it an explosive. DHS, recognizing this difference, decided to regulate these two different chemicals in keeping with their respective hazard.


Ammonium nitrate explosives are, by far, the more hazardous of the two forms. In keeping with this fact, DHS has set the Release STQ for the explosive at 5,000 pounds, the same as all other explosives. The Release STQ is set to acknowledge that if this amount of ammonium nitrate were detonated at the chemical facility that there is the potential for significant off-site consequences.


As with other explosives there is also the threat that a terrorist would steal ammonium nitrate explosives for use off-site. DHS has addressed this with a separate Theft/Diversion STQ of 400 pounds. The material difference between these two STQs is that for material to be counted in the Theft/Diversion STQ it has be packed in shippable containers; containers that a terrorist could reasonably be expected to steal. The 400 pound STQ is substantially less than the 2,000 pound STQ found in the earlier version of this list. Meeting the STQ in either case (or both cases) would trigger the requirement for the facility to complete a Top Screen notification to DHS.


Ammonium Nitrate, the fertilizer, is not much of an explosion threat in its commercial form. For this reason, DHS has not set a Release STQ for this type of Ammonium Nitrate; it does not pose a significant on-site explosion risk. It can, however, be converted to an explosive by adding an accelerant such as fuel oil or various solvents. With that in mind DHS did set a Theft/Diversion STQ for the fertilizer form of Ammonium Nitrate (as an explosive precursor) at 2,000 lbs. This STQ is the same as the 2,000 pound STQ found in the original list.


DHS has implemented a set of dilution rules that allow for some chemicals to only be counted in their actual amount in a mixture. For example, a 10,000 lb mixture containing isobutene in a concentration of 10% would only count 1,000 lbs of that mixture as isobutene. That rule does not apply to explosives or explosive precursors. The total amount of the mixture, as long as it meets the minimum concentration listed in the table, will be counted when calculating whether or not the amount on hand meets or exceeds the STQ.


For the explosive grade of ammonium nitrate the minimum concentration is listed as “ACG” or any commercial grade. In other words, any concentration of ammonium nitrate that is sold commercially as an explosive meets the minimum concentration limit and the entire amount on site is counted towards the Release STQ. That amount packed in shipping containers will be counted towards the Theft/Diversion STQ. The fertilizer grade ammonium nitrate has a listed minimum concentration of33%. Thus any mixture of ammonium nitrate that contains at least 33% ammonium nitrate (not the lower % nitrogen that is commonly listed on the fertilizer label), if packaged in shipping containers, will be counted towards the Theft/Diversion STQ.


Mr. Hsu clearly had his facts wrong when he stated that; “DHS also increased the disclosure threshold for ammonium nitrate from 7,500 pounds to 10,000 pounds.” First off, DHS had initially listed the STQ as 2,000 lbs (not 7,500 lbs) and the old Top Screen Manual clearly listed this as a Theft/Diversion issue not an on-site Release issue. The Theft/Diversion STQ was significantly reduced from 2,000 pounds to 400 pounds for the explosive form and a Release STQ for the explosive form has also been set. Set at 5,000 pounds, this STQ would capture all manufacturing and nearly all distribution facilities for this material. The Theft/Diversion STQ for the fertilizer form remains at 2,000 pounds reflecting the fact that terrorists would have additional work to do to convert this material to the explosive form of this chemical. All in all, DHS has significantly tightened the reporting requirements on ammonium nitrate.


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