• bjones148

The "Return" of RMP

If you’ve been in the environmental business long enough you’ve come to realize that every time a new administration takes office in Washington things also change at EPA. These changes not only come in the form of new senior EPA staff but also in the way EPA goes about its business, ranging from changes to regulations (sometimes more, sometimes less) to how aggressively EPA enforces its regulations.

Since the Biden administration has taken office, we have noticed one such change—letters being sent to a large number of industries asking them questions related to their Risk Management Program, or RMP. The reality is there are more than a few facilities who have never even heard of RMP and therefore don’t know how to respond—and as a result these letters can be kind of scary. With that in mind I thought we’d take a moment to give a quick primer on RMP.

Way back in the 1990s (which is why many today haven’t heard of it) EPA published the “Chemical Accident Prevention Provisions,” which is codified in 40 CFR 68. It applies to sources that handle, manufacture, or store toxic substances in amounts greater than threshold quantities established in Appendix A of 40 CFR 68 ( Keep in mind you don’t have to be a major industrial facility to be subject to this rule—operations such as propane storage facilities, chemical distributors, warehouses, and facilities that use ammonia refrigeration often are subject.

The goal of this program is to prevent accidental releases of toxic substances that can cause serious harm to the public. To do this the program requires subject facilities to develop and implement a Risk Management Program for their specific operations. Included in this RMP is an air modeling analysis that addresses air pollution impacts from both a worst-case release of a toxic substance (think a storage tank that ruptures and releases all its contents) and an alternative/more realistic release of a toxic substance (think a loading hose that gets unhinged). That modeling establishes how far out from the facility the potential harmful impacts can occur and then identifies public receptors within that area—locations where the public would be at risk should an accident occur. That information and more is required to be communicated to EPA and ultimately becomes available to the public.

In most cases the modeling that needs to be conducted is what’s called “dense gas” modeling, because typically the toxic substances covered by this rule behave as a dense gas when they hit the atmosphere. For instance, ammonia is liquefied under pressure in many refrigeration systems. If that ammonia is suddenly released to the atmosphere it forms a mixture of vapor and very fine liquid droplets, and those droplets quickly cool the nearby air such that a cold mixture of air and ammonia vapor is formed. This mixture is denser than air and thus needs to be modeled appropriately (i.e., the dispersion model most-often used for industries, AERMOD, is not the right model in this case).

If you receive one of these letters and aren’t sure how to respond, feel free to reach out to BSM. The first step is to determine if you’re subject to this rule and then, if you are, to conduct some dispersion modeling to figure out what the implications are. BSM can help guide you through this process and bring you into compliance with this rule if you’re not already.

45 views0 comments

Recent Posts

See All
  • LinkedIn

©2021 by Blue Sky Modeling. Proudly created with