“Quantity and persistence will get you the outcomes you need.” — James Altucher
One of the challenges of process hazard analysis is risk assessment. To determine whether additional risk reduction is required, the team must quantify the risk and compare it to risk tolerance criteria. For the risk tolerance criteria to be useful to the team, it must consist of categories—both for likelihood and for consequence severity—that separate by orders of magnitude.
On the likelihood side, it is easy to separate categories by orders of magnitude: more than once a year, more than once a decade, more than once a century, more once a millennium, and so on. When assets are the receptors of concern, it is also easy to separate consequence severity categories by orders of magnitude: less than $10,000, less than $100,000, less than $1,000,000, less than $10,000,000, and so on.
When environmental harm is the consequence of concern, however, organizations struggle. The first struggle is in deciding on the receptor to represent the environment. Then, the organization must decide on how to quantify that receptor so that it can be separated into categories separated by orders of magnitude.
One approach is to use the amount released as a surrogate for environmental damage. This approach lends itself to quantification and assignment to orders of magnitude. The problem is that not all releases are equivalent. A 100-pound release of brine does not do the same harm to the environment that a 100-pound release of 1-methyl-2-ethyl death does.
To address this problem, many organizations base their consequence severity categories for environmental harm on reportable quantities—RQs.
What Are RQs?
The government requires inadvertent releases to be reported: some to the National Response Center by calling 1-800-424-8802, some to CHEMTREC by calling 1-800-424-9300, some to the local or state emergency planning committee, and some to more than one of these resources. But some releases are so small that they don’t need to be reported.
Spilling a bottle of fingernail polish remover, which is essentially pure acetone, would not require notification. Spilling a tank truck load, on the other hand, would. Somewhere between a few fluid ounces and a few thousand pounds is an amount that would require reporting. That amount is the RQ.
Who Sets RQs?
RQs concern the release of chemicals to the environment. So, it should come as no surprise that the U.S. Environmental Protection Agency (EPA) is the federal department that takes the lead in setting RQs. The EPA has many concerns, however, so they have several regulations about RQs.
The first is for oil spills. The EPA sets the RQ for oil spills in 40 CFR 112.4a of the Oil Pollution Prevention standard. The RQ for a single discharge of oil is 1,000 U.S. gallons. If a facility has two or more discharges of oil within a 12-month period, then the RQ is 42 gallons per discharge. By oil, the EPA means petroleum products; animal oils, fats, and greases; and vegetable oils.
The EPAs second concern is for hazardous substances under the Superfund, Emergency Planning, and Community Right-to-Know programs. With these programs, the EPA has developed lists of hazardous substances and extremely hazardous substances (EHSs) and assigned an RQ to each substance.
The mother of all EPA RQ lists is in 40 CFR 302.4, known as the CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act) List. Not counting hazardous wastes and radionuclides, the CERCLA List includes 1,132 chemicals (counting several synonyms). The RQs range from as little as 1 pound to as much as 5,000 pounds, depending on the chemical. Acetone, for instance, has an RQ of 5,000 pounds while mercuric cyanide has an RQ of 1 pound.
A second EPA list of RQs is the EPCRA (Emergency Planning and Community Right-to-Know Act) List, found in 40 CFR 355 Appendix A. Coincidentally, it list 355 chemicals. Of these, 153 are also on the CERCLA List with exactly the same RQs. The EPCRA List has another 202 chemicals, however, that are not on the CERCLA List. Each has their own RQ.
Are There Other Lists With RQs?
There are other lists of chemicals with RQs.
As part of its enforcement of the Clean Water Act, the EPA has a list in 40 CFR 117.3. Table 117.3 lists 296 chemicals. Each of them, however, is also on the CERCLA List with the same RQ shown on the CERCLA List. In terms of quantifying consequence severity during a PHA, the CWA List has nothing to add.
Because releases can also result from accidents during the transportation of hazardous substances, the Department of Transportation also has a list of chemicals with associated RQs, found in 49 CFR 172.101 Appendix A. The DOT list is supposed to be identical to the CERCLA List, and for the most part it is. The only differences are that the CERCLA List includes 1-Bromopropane (aka n-Propyl bromide), which the EPA added to the list on April 8, 2022, and includes CFOAs and CFOSs, which the EPA added to the list on April 19, 2024. This is because the DOT last updated it list on March 31, 2008. So, again, this list has nothing to add in terms of quantifying consequence severity during a PHA.
Note: A link on the Pipeline and Hazardous Materials Safety Administration (PHMSA) website takes readers to an older version of §172.101 Appendix A that is out of date and should not be used.
What About Threshold Quantities (TQs)?
The OSHA PSM standard and the EPA RMP standard use separate threshold quantities (TQs) as the basis for determining whether a facility is covered under those regulations. Other regulations use threshold quantities as well. The purpose of TQs is different, however, and usually much greater than RQs. They would not be a good basis for quantifying consequence severity during a PHA.
What If An RQ Has Not Been Set?
Between the CERCLA List and the EPCRA List, the EPA has established RQs for 1,334 chemicals. There is also the RQ for all oils, fats, and greases, regardless of origin. However, the Chemical Abstract Service lists over 290 million chemicals substances. Clearly, there are chemicals without RQs. What should you do then?
RQs have discrete quantities: 1 pound, 10 pounds, 100 pounds, 1000 pounds, and 5000 pounds. At a typical specific gravity of 0.85, 42 gallons of oils is about 300 pounds. Those are the choices. Given some knowledge of the hazardous properties of a chemical, it shouldn’t be too hard to assign a pseudo-RQ for the purposes of risk assessment of chemicals not otherwise addressed by the EPA. Doing this won’t impose a regulatory burden. It will just make it easier for a PHA team to do a risk assessment.
