That being said, the term "material modification" is not as straightforward as it might seem.
Material modifications can include a whole host of changes, and for that reason, the Department cannot provide an exhaustive list of material modifications. In general, though, DHS expects that material modifications would likely include changes at a facility to chemical holdings (including the presence of a new chemical, increased amount of an existing chemical, or the modified use of a given chemical) or to site physical configuration, which may (1) substantially increase the level of consequence should a terrorist attack or incident occur; (2) substantially increase a facility’s vulnerabilities from those identified in the facility’s Security Vulnerability Assessment; (3) substantially effect [sic] the information already provided in the facility’s Top-Screen submission; or (4) substantially effect [sic] the measures contained in the facility’s Site Security Plan.
Material Modifications Triggering Resubmission
Some changes at the facility are tied directly to the CFATS Appendix A Final Rule, which lists the Chemicals of Interest (COI) and their Screening Threshold Quantities (STQs) that trigger initial Top-Screen submission. These modifications would, undoubtedly, be considered "material," since they are tied directly to the initial CFATS trigger (i.e. the Top-Screen). For example, a facility that acquires a new COI at or above the requisite STQ has a "material modification" that triggers re-submission of its Top-Screen. Alternatively, a facility that reduces a COI below its STQ or eliminates a COI entirely has made a "material modification" that could act in its favor, and should re-submit its Top-Screen.
Potentially Material Modifications
Other potential modifications made at the facility, however, are less clear as to their materiality. In essence - what does "material" mean?
For example, a facility that stores 5,000,000 pounds of Methane, which is listed as a Release-Flammable COI, in below-ground tanks, responds to demand spikes by adding 250,000 additional pounds of Methane, for a total increase of 5%. Methane is the only COI stored by the facility. Is this a "material modification" as envisioned by DHS and CFATS? On the one hand, the facility is increasing the amount of Methane being stored, which reflects, as explained in the CFATS Preamble, an "increased amount of an existing chemical." On the other hand, the increase does not change the facility's initial storage of Methane at an amount significantly above the Appendix A STQ, which would arguably not substantially affect the facility's original Top-Screen and/or security vulnerability.
Another example of a facility modification that may or may not be considered "material" for purposes of 6 C.F.R. §27.210(d) is the replacement of one National Fire Protection Association (NFPA) 4 material with another NFPA 4 material, where all other factors (such as storage location, volume, facility security measures, etc.) remain the same.
In light of the gray areas surrounding "material modifications" and resubmission of Top-Screens, many companies may face facility-specific questions regarding modifications and whether they merit a new Top-Screen submission. To be on the safe side, facilities should err on the side of resubmission when in doubt. However, they should do so knowing that resubmission opens the door for resubmission of a new Security Vulnerability Assessment (SVA) and, possibly, resubmission and alteration of an already-approved Site Security Plan (SSP).