Multiphase Solid Waste Ignitability Rule: Regulating the Unknown

Deciding the regulatory status of solid phase wastes is difficult but determining whether those wastes should be evaluated as ignitable liquids at some time in the future is nearly impossible. Yet, that is what the law requires. 

In fact, EPA requires generators look into a magic ball and determine if their wastes will ever settle or separate in transit into a multiple-phase waste, and if so, are any of those phases ignitable liquids—seemingly ignoring the mixture rule.

Background

Under the Resource Conservation and Recovery Act (RCRA), every facility must determine if solid wastes accumulated onsite exhibit one or more of the characteristics of a hazardous waste or are otherwise specifically listed by EPA as a hazardous waste. 40 CFR 262.11. The characteristics of a hazardous waste are ignitability, corrosivity, reactivity, and toxicity. 40 CFR 261.20-24. By definition, a “solid waste” may be a solid, liquid, or semi-solid phase material or even contained gases.

Problem: Ignitability Characteristic Test for Different Phases

Because of the lack of ASTM standards, ignitability for solids and liquids are not measured the same. Where a waste is truly a liquid, it is considered ignitable if it has a flash point less than 60 °C (140 °F) using a prescribed EPA methodology; solid phase materials are ignitable if under standard temperature and pressure they are readily combustible through friction, absorption of moisture or spontaneous chemical changes and, when ignited, burn so vigorously and persistently that it creates a hazard. 40 CFR 261.21(a),(b).

Solution: Evaluate the Phases Based on the Container as a Whole

Certain containers of solid wastes pose a problem because the contents settle or separate into multiple phases. In 2020, EPA provided guidance on multi-phase waste containers, and it is not an easy read.

EPA declares the generator must evaluate each phase of waste to determine if the waste phase is a characteristic hazardous waste. This is not so easy when it comes to the characteristic of ignitability. 85 Fed. Reg. 40594, 40601(July 7, 2020). A generator of a waste should consider the individual liquid phases of a multiple phase waste under the criteria in 40 CFR § 261.21(a)(1) and non-liquid phases of a multiple phase waste under the criteria of 40 CFR § 261.21(a)(2).

A bigger problem is deciding what physical state a particular phase is, i.e., is the phase a regulatory “liquid” and when should the phase be tested as a regulatory “solid.” EPA recommends generators use the Paint Filter Liquids Test (EPA Method 9095B) in determining whether to apply the ignitability test for liquids to any phase in the container:

When determining if a waste contains multiple phases, a generator has to consider the properties of the waste as generated and the properties of the waste under the conditions that it is likely to encounter during normal management (e.g., during initial accumulation, storage, transport, treatment and disposal). A generator should also consider the Paint Filter Liquids Test to be the minimum requirement for determining whether a solid phase waste contains a liquid phase. Id.

Knowing the characteristic of a specific phase within a multiphase container is not enough to characterize contents of an entire container for offsite disposal, however. Federal regulations require the hazardous waste characterization to be made based on a “representative sample” of the multiphase waste container. 85 Fed. Reg. at 40601. A “representative sample” means a sample of a universe or whole…which can be expected to exhibit the average properties of the universe or whole.” 40 CFR 260.10. As a result, the generator must use knowledge or testing to determine if the remaining portion of wastes in the container changes the results of tests on an individual phase before shipment.

Conclusion: Characterize the Entire Waste, Not the Phase

Generators accumulating solvent-based wastes may wish to carefully consider the EPA guidance. Sampling is only reliable if it is “representative” of the hazardous waste unit, and that may be the container in which it is accumulated. This means even if one phase appears to be “ignitable,” the waste may not exhibit the characteristic if a representative sample of the waste as a whole does not meet the regulatory definition of ignitability. And, the phase may not be considered a liquid and subject to a flashpoint test unless it fails the paint filter test.