Dhs Publishes Top Screen Requirements – Flammable Chemicals

The Top Screen guidance introduces another concept that they use to evaluate the hazard associated with chemicals on site, the AHQ (Area of Highest Quantity). The AHQ tries to take into account the fact that if a chemical is distributed over a wide area in a facility it will probably be less of a risk during a terrorist attack, because it will be harder to release all of that chemical. To determine the AHQ you must determine where the largest concentration of the chemical is within a circle of a diameter of 170 feet. Thus, if there were a number of storage tanks on site, but were widely scattered you would use the largest tank or combination of tanks that would be in a single 170 foot diameter circle to determine the AHQ amount.

There are 89 chemical on the Flammable Chemicals list. These chemicals made the list because DHS believes that, if released, they will form a vapor cloud and, if ignited, have the potential for significant acute adverse consequences for human life or health due to explosion and fire. After selecting which flammable chemical(s) the facility has on site at or above the STQ limit the Top Screen will require the Submitter to provide the maximum amount on site and the maximum amount within the AHQ for each chemical identified. No other questions will be asked about flammable chemicals.

This will be a time consuming process to complete all of the Top Screen information, but it will not have to be done at a single sitting. The incomplete information will be saved between multiple sessions. Many facilities will not have to complete the entire 80 page process. There are many places, where depending on the answers to various questions, the Top Screen will notify the Submitter that the facility is not a high-risk facility and no further action is needed under 6 CFR part 27 until something changes at the facility. Some facilities will be told at the end of the submission that they are preliminarily designated a high-risk facility and must complete a Security Vulnerability Assessment (SVA) within 90 days. Most facilities, however, will have to complete the entire Top Screen only to be told that they might be declared a high-risk facility, but that determination will be made after further review at DHS. Those facilities will have to wait for a letter telling them what the preliminary out come will be.