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Unknown Wastes

Have you ever come across one or more drums of material at your facility, and you truly have no idea what’s in them nor can you determine where they came from? Or maybe someone did some “midnight dumping” of wastes onto your property. What do you do with this unknown waste material?

In some cases, particularly if individuals are dumping wastes illegally onto your property, calling the state or local hazardous materials response team may be the best answer. These groups will often take responsibility as the generator of the waste, and the proper characterization will be up to them. In other situations, your facility either is the rightful generator or wants to take on that responsibility. Then what do you do?

EPA considers illegally dumped hazardous wastes to be a discharge and thus subject to the immediate response regulations at §§264.1(g)(8), 265.1(c)(11), and 270.1(c)(3). Most RCRA management and permitting requirements do not apply during an immediate response. To qualify for the exemption, the treatment or containment activities must be during the initial, immediate response to the discharge. Once the immediate threat passes, all applicable RCRA standards apply, including the generator accumulation provisions of §§262.16–17. The exemption applies only to treatment and storage activities; it does not relieve anyone of complying with RCRA requirements for the disposal of hazardous waste. [RO 14031]

If the unknown materials are determined to be solid wastes (i.e., you want to get rid of them), you must make a hazardous waste determination just like for any other solid waste. You can do this using testing or knowledge. Determining whether an unknown material exhibits any of the hazardous waste characteristics or is a listed hazardous waste is discussed in the next two subsections.

Determining if unknown wastes exhibit a characteristic

It is usually difficult to determine if an unknown waste is characteristically hazardous based solely on visual inspection and knowledge of how the characteristics are defined. Thus, a sample of the unknown will usually have to be sent for analysis. We have heard many different versions of what to ask the lab to test for, but the following is a consensus supplemented with limited EPA guidance:

• Ignitability—This should include a flash point test if the unknown is a liquid; the flash point method should be one of those specified in §261.21(a)(1). Oxidizers per §261.21(a)(4) are sometimes screened for using potassium iodide (KI) paper, which is especially suited to detect strong oxidizers. Samples that screen positive can be tested using SW–846 Method 1040—Test Method for Oxidizing Solids if confirmation testing is deemed necessary.
• Corrosivity—This should include a Method 9040C pH meter test if the unknown is aqueous.

Sometimes generators make pH determinations using other analytical methods. For example, pH paper can be used to make rough acid-base measurements. However, such a corrosivity determination would fall under the category of generator knowledge because the prescribed method (Method 9040C) was not used.

• Reactivity—Talk to the lab about their recommendations on testing for this characteristic. Some people still ask (and some states require) that the rescinded HCN/H₂S release threshold tests be run to test for §261.23(a)(5) reactivity. Others just request total and amenable cyanides/sulfides analyses per Methods 9010C, 9012B, 9030B, 9031, and/or 9034.
• Toxicity—Have the lab run TCLP for all 40 constituents. According to EPA/530/R-12/001, once TCLP is run, the extract obtained may be analyzed for the 40 constituents listed in §261.24 by any method, as long as that method has documented quality control and is sensitive enough to meet the regulatory limits. The agency noted that the following EPA test methods could be used in this step:

• Methods 3010 and 6010 for arsenic, barium, cadmium, chromium, lead, silver, and selenium;
• Method 7470 for mercury;
• Methods 3510 and 8081 for pesticides;
• Method 8151 for herbicides;
• Methods 5030 and 8260 for volatile organics; and
• Methods 3510 and 8270 for semivolatile organics.

As an alternative to running TCLP (which is quite expensive), some facilities will ask the lab to run totals for the 40 constituents in §261.24. Based on those results, TCLP may then be requested only for those constituents with the potential to exceed regulatory levels.

• PCBs—Although PCBs are regulated by TSCA, not by RCRA, unknowns should be tested for these constituents because 1) of how common they are in older, oil-based substances, and 2) the regulatory requirements associated with their management depend on the PCBs concentration in the as-generated waste before treatment.
• Asbestos—Regulated by CAA, TSCA, and OSHA, not RCRA, asbestos is usually only tested for where friable asbestos-containing material (ACM) may be present. ACM was commonly used in construction for thermal insulation systems, fireproofing, and acoustical insulation.

Determining if unknown wastes are listed

Hazardous waste listings are based on the sources of, or the processes that generated, the wastes rather than the concentrations of hazardous constituents. Therefore, analytical testing alone, without information on a waste’s source, will not produce information that will conclusively indicate whether a given waste is a listed hazardous waste. [RO 13181]

Sometimes, it is hard to determine the source of the material or contamination, and thus difficult to tell if a material is a listed waste. If a good-faith effort has been made to determine if a material is a listed waste but a determination is inconclusive because documentation on the source or process is unavailable, EPA allows facilities to assume the material is not a listed waste. (See, for example, 53 FR 51444, 55 FR 8758, and 61 FR 18805.) Consequently, if the material does not exhibit a hazardous waste characteristic, the RCRA hazardous waste regulations do not apply. This has been EPA’s long-standing policy, reaffirmed in RO 14291.

Accumulation time for unknown wastes

When materials of unknown origin and composition are discovered that are subsequently going to be discarded (i.e., they are solid wastes), they must be characterized before disposal. If sampling and analysis are used for this purpose, and the results come back stating that the waste is indeed a RCRA hazardous waste, when does the generator accumulation time (i.e., the 90- or 180-day clock) specified in §§262.16–17 begin?

Sections 262.16–17 allow SQGs and LQGs to accumulate hazardous waste onsite for 90/180/270 days without a RCRA permit or interim status if certain conditions are met. These conditions include:

• The date that the accumulation period begins must be clearly marked on each container, and
• Each container and tank must be labeled clearly with the words “Hazardous Waste” and an indication of the hazards of the contents.

According to EPA, if a container holding unknown waste (which is later discovered via analysis to be a RCRA hazardous waste) is not labeled as “Hazardous Waste” or marked with the accumulation start date as soon as the waste is put in the container, the generator has not met the requirements for the storage permit exemption. Consequently, it is operating a hazardous waste storage facility that needs a RCRA permit.

To qualify for the 90- or 180-day accumulation exemption, all containers of unknown waste should be labeled as hazardous and dated when the waste is first generated, even if the contents are not yet known to be hazardous. The accumulation period does not begin after the waste is analyzed and you get the results back from the lab saying the waste is hazardous. [EPA/233/B-00/001, RO 11424] One way to indicate the designation of the unknown waste may change is to add the words “Pending Analysis” after “Hazardous Waste.”

EPA reiterated its position in 2016:

“[T]he agency has determined that most generators make a hazardous waste determination by using knowledge of their processes, including feedstocks and possible side reactions, and other materials used at the facility to evaluate whether waste is hazardous or not. In order to properly classify and manage waste, generators must make a hazardous waste determination when the waste is first generated.…

“We have and continue to recognize that situations will occur where a generator is not able to make an accurate waste determination based on knowledge alone, and the generator will need to send a representative sample of the waste to be tested. However, as the EPA has stated in the past, the generator must manage the waste as hazardous waste until the results of the test are received, and continue to manage it as hazardous waste if the hazardous waste determination is confirmed by the test.

“The agency is also aware that many generators, such as academic and industrial laboratories, generate new or different waste streams frequently, and that making hazardous waste determinations for multiple waste streams is more difficult than when a generator has a small number of waste streams that seldom vary. However, EPA stresses that in the laboratory setting, it may be even more important to make accurate hazardous waste determinations at the point of generation, so that emergency scenarios involving mixing of incompatible wastes or other dangerous situations can be avoided and lab worker safety maintained.” [81 FR 85750–1]

States may have a different interpretation than this federal guidance, so check with your state on accumulation time for unknowns.