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In the United States, hazardous wastes are subject to regulations mandated by the Resource Conservation and Recovery Act (RCRA). Every month, we provide clear, in-depth guidance on a different aspect of the RCRA regulations. The information presented here is an excerpt from McCoy’s RCRA Unraveled, 2019 Edition.

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Ignitability

From §261.21(a), a solid waste exhibits the characteristic of ignitability (and is a D001 hazardous waste) if a representative sample of the waste meets any of the following criteria:

  • It is a liquid (other than an aqueous solution containing <24% alcohol by volume) with a flash point <140°F. [§261.21(a)(1)]
  • It is a nonliquid that 1) can ignite under standard temperature and pressure (68°F and 1 atm) through friction, moisture absorption, or spontaneous chemical changes; and 2) burns so vigorously and persistently after ignition that it creates a hazard. [§261.21(a)(2)]
  • It is an ignitable compressed gas defined as a compressed gas that 1) is flammable when in a mixture of 13% or less with air (i.e., its lower flammability limit is 13% or less), or 2) has a flammable range with air of more than 12% (i.e., the difference between its upper and lower flammability limits is greater than 12 percentage points) regardless of the lower flammability limit. [§261.21(a)(3)]
  • It is an oxidizer, which is a substance that yields oxygen readily to stimulate the combustion of organic matter. [§261.21(a)(4)]

EPA’s objective with the ignitability characteristic is to require hazardous waste management for those wastes “capable of causing fires during routine transportation, storage, and disposal and wastes capable of severely exacerbating a fire once started.” [May 19, 1980; 45 FR 33108] Each of these four categories of ignitable wastes is explored in more detail below.

Note that EPA has proposed changes to the above definition of ignitability in §261.21. See our article discussing these proposed changes.

Liquids with low flash points

Liquids with a flash point <140°F make up the majority of ignitable wastes. Almost all of the nonchlorinated solvents have flash points below 140°F and so exhibit the ignitability characteristic when they become wastes. Spent paint thinners, contaminated fuels, various waste alcohols and other liquids, and some adhesives are also typically ignitable. Flash points of some common materials are listed in Table 1.

Table 1

EPA’s definition of an “ignitable” liquid is a little different from DOT’s definition of a “flammable” liquid. A DOT flammable liquid is a liquid with 1) a flash point <140°F, or 2) a flash point >100°F that is intentionally heated and offered for transportation at or above its flash point. [49 CFR 173.120(a)] The primary reason EPA selected the flash point level of <140°F for D001 wastes was that these temperatures can be encountered during routine storage and transportation conditions (e.g., liquid waste in a black drum sitting in the sun on a summer day). EPA specifically chose the term “ignitable” to try to eliminate confusion between a RCRA ignitable liquid and a DOT flammable liquid.

Determining if a waste is a liquid

Since the criteria for ignitable waste determinations are different for liquids versus nonliquids, the generator must first determine if his/her waste is a liquid. There are a number of ways this can be accomplished. A knowledge-based determination may be made: “EPA believes that, for purposes of the characteristics of ignitability and corrosivity, it will generally be obvious whether or not the waste is a liquid.” [April 30, 1985; 50 FR 18372] For instance, a generator can use knowledge to determine that waste paint thinner or solvent is a liquid.

For wastes with both a liquid and solid phase (semisolids), however, it can be more difficult to make such a determination. For these materials, generators commonly run the Paint Filter Liquids Test (Method 9095B in SW–846). This test, which was added to SW–846 in 1985 [50 FR 18370], is used to determine the presence of free liquids in a representative sample of a waste. [RO 13601] The sample is placed in a conical paint filter and allowed to drain for 5 minutes; if even one drop of liquid passes through the filter in that time frame, the sample contains free liquid. Although the paint filter test was added to the agency’s test methods to ensure no free liquids were disposed into landfills, EPA noted that “this test provides a practical method of testing ignitable and corrosive materials to determine the presence of liquids, and assists the regulated community in complying with the Part 261 requirements until further evaluation is done.” [50 FR 18372]

Chapter 7 of SW–846 (which discusses the four hazardous waste characteristics and how they should be evaluated) currently includes the following statement: “Use Method 9095…to determine free liquid.” EPA proposed in 1993 to modify that language by replacing the paint filter test with the pressure filtration technique specified in Method 1311 (the toxicity characteristic leaching procedure or TCLP). [August 31, 1993; 58 FR 46052] Although the agency never finalized that proposal, the pressure filtration technique remains its preferred method:

“The definitive procedure for determining if a waste contains a liquid for the purposes of the ignitability and corrosivity characteristics is the pressure filtration technique specified in Method 1311. However, if one obtains a free liquid phase using Method 9095, then that liquid may instead be used for purposes of determining ignitability and corrosivity. However, wastes that do not yield a free liquid phase using Method 9095 should then be assessed for the presence of an ignitable or corrosive liquid using the pressure filtration technique specified in Method 1311.” [January 13, 1995; 60 FR 3092]

The pressure filtration technique specified in Method 1311 defines a “liquid” as the material that passes through a 0.6- to 0.8-micron filter when a representative sample of the waste is subjected to a 50-psi differential pressure. Clearly, this is a more stringent procedure than the gravity-based paint filter test, but EPA has never codified this requirement in the regulations or in SW–846—it is just guidance. In fact, two weeks after the agency issued the above-noted preamble language preferring the pressure filtration technique over the paint filter test, it released guidance noting that, until it finalizes the proposed change in SW–846, “the paint filter test is the method to use to determine if a free liquid is present for ignitability determination.” [RO 11935] In other guidance found in EPA’s RCRA FAQ Database (https://waste.zendesk.com/hc/en-us/articles/217452497), EPA takes the position that if the paint filter test does not produce free liquid, the generator must use the pressure filtration test. As such, the guidance on which methodology to use is conflicting. The most conservative approach would be to use the pressure filtration technique. Table 2 summarizes the “liquid” definition for the ignitability characteristic.

Table 2

Flash point testing

Whether a generator uses knowledge, the paint filter test, or the pressure filtration technique, the ignitability of liquids must be evaluated using knowledge or flash point testing. If testing is used, flash point must be determined using a Pensky-Martens closed-cup tester (SW–846 Method 1010A) or a Setaflash closed-cup tester (SW–846 Method 1020B). Only one test method needs to be used. The choice of the method should be based on the applicability of the method to the waste being tested. [RO 11594] For example, the Setaflash method is not applicable to liquids with nonfilterable suspended solids and viscosities above 150 stokes at 25°C. The Pensky-Martens test can be used for liquids that contain nonfilterable suspended solids.

Both of the closed-cup flash point testers specified in the regulations were originally developed by ASTM and work about the same way. A sample of liquid is put into a metal cup, which is then placed in the test apparatus. The lab technician toggles a switch on the apparatus, which directs a test flame into the headspace of the cup, and he/she watches for a flash due to ignition of the fumes or vapors coming off the liquid. If the sample flashes while at room temperature (e.g., 70°F), then the flash point of the liquid is 70°F or less. If no flash is detected, the technician increases the sample temperature and toggles the switch again. If the sample still has not flashed when its temperature is raised all the way to 140°F, then the generator can conclude that the waste is not an ignitable liquid. [RO 12909]

When testing is used for determining compliance with the <140°F criterion, closed-cup flash point testing must be employed. Note that flash point can also be obtained through open-cup testing, but those results are valid only if the measured flash point is <140°F. “Ordinarily, open-cup tests…will produce higher flash points than the closed-cup tests required by EPA.” [RO 12296]

A flash was observed when testing a solvent mixture that should not (based on composition) be ignitable. For example, a flash was observed at 68°F when evaluating a spent solvent containing 99% Freon 113 and trace levels of cyclohexane. Should this spent solvent be considered ignitable under RCRA?

Yes, the spent solvent will be considered ignitable under RCRA based on RO 12909.

Some confusion has arisen over the use of flash point testing for wastes that are essentially all solids (e.g., solvent-contaminated rags or gasoline-contaminated soil) or for semisolid wastes containing both a liquid and solid phase. According to EPA, “[n]either test, however, is approved by ASTM for use in evaluating the flash point of solids or sludges.” [OSWER Directive 9443.00-1A] “If your samples contain filterable solids, they are not amenable to the Pensky-Martens flash point test. Flash point testing is only appropriate for liquid samples. It should not be applied to solids.” [RO 13759] See also RO 12909, 13550, and 14669.

Based on this guidance, wastes that are essentially all solids or are semisolids should be evaluated using the paint filter test and/or pressure filtration technique. If no free liquid comes through the filter, the waste is not a liquid and will not be D001 via the §261.21(a)(1) criteria. [RO 11619, 11787, 13328] However, the waste may still be an ignitable solid or a DOT oxidizer (which are D001 wastes, as discussed below). We’ve heard of people running flash point tests on solvent-contaminated rags or gasoline-contaminated soil; if a flash from one of these materials is recorded by the lab at a sample temperature <140°F, the generator may think he/she has to apply the D001 code to the waste when they really may not have to.

“If a solid flashes using some modification of the flash point test, this may indicate there is a potential problem with the sample, such as contamination with ignitable volatiles, and further investigation may be in order. The flash point test alone is not definitive for determining the ignitability of solids, but may be used with other evidence [e.g., the criteria in §261.21(a)(2)] to build a case for a waste being classified as an ignitable hazard.” [RO 13761]

It is also our understanding, however, that some waste haulers and TSD facilities may require flash point data on certain waste solids that do not contain free liquids as a condition of transporting or accepting the waste. If running the flash point test is a condition of doing business with such an entity, then the generator will either have to comply or find another supplier. But, even if a flash is detected from such solid materials at <140°F, the D001 code still will not have to be applied to such materials unless they meet the §261.21(a)(2) or (a)(4) criteria discussed below. “You are correct in asserting that the absence of free liquids precludes the application of the ignitability characteristic as defined in §261.21(a)(1).” [RO 11787]

If the paint filter test or pressure filtration technique produces a free-liquid phase from wastes that are solid or semisolid, EPA says you “should separate the solid/liquid phases of your samples and test each phase separately; liquids by flash point and solids by the DOT procedure [Method 1030 in SW–846 (discussed below)].” [RO 13759; see also 50 FR 18372] Then what? “A waste liquid or mixture containing a free-liquid phase (as defined by our paint filter liquids test) is ignitable under RCRA if the waste (or liquid phase) has a flash point <140°F.” [Emphasis added.] [RO 11619] “All such wastes which contain or consist of liquids which have a flash point below [140°F] are to be considered as ignitable wastes.” [RO 12034]

Our discussions with industry personnel corroborate EPA’s previous guidance. If either of the phases fails their respective ignitability test, the entire mixture should be considered D001 hazardous since it will be disposed as a mixture of solids and liquids.

That’s the theory. The reality is a lot fuzzier. Most people we talked to about this matter are using the paint filter test to determine if a waste is a liquid. But there is no apparent consensus as to what is subsequently tested for flash point: just the free-liquid phase generated from the filter test or the entire waste matrix (liquid plus solids). Testing just the free-liquid phase is more conservative, because it is almost certainly going to have a lower flash point than the entire waste matrix. If the free-liquid phase is what is tested and has a flash point <140°F, these facilities would designate the entire waste as D001. Based on EPA’s guidance regarding the applicability of the flash point tests, this appears to be the more defensible approach. Additionally, due to the physical limitations associated with the two flash point testers, it is often difficult to introduce much of the solids into the test cup anyway. (Of course, facilities that have a waste analysis plan must conduct ignitability testing as prescribed in their plan.)

The alcohol-content exclusion

The characteristic of ignitability does not apply to an aqueous solution that contains <24% alcohol by volume, even if it has a flash point <140°F. This exclusion, set forth in §261.21(a)(1), was originally intended to exclude waste alcoholic beverages and some types of latex paints from hazardous waste management. These materials exhibit low flash points due to their alcohol content but do not sustain combustion because of their high water content. [45 FR 33108] The waste must have some alcohol in it (but <24%) to qualify for the exclusion. [RO 12274]

The alcohol exclusion is a carryover from DOT’s old regulatory definition of combustible liquids. In those DOT regulations, the term “aqueous” was defined as no less than 50% water. To remain consistent with DOT’s approach, EPA has interpreted “aqueous solution” for the purpose of the alcohol exclusion to mean a solution containing at least 50% water by weight. [RO 11060, 13548] Note that this definition of “aqueous” associated with the ignitability characteristic is considerably different from the one used for determining corrosivity. (See Table 2.)

EPA has also clarified that the exclusion applies to wastes that contain a nonalcoholic component (e.g., a mixture of 77% water, 13% alcohol, and 10% nonalcoholic liquid). In other words, the presence of a nonalcoholic constituent will not require the waste to be regulated as D001 if the mixture has a flash point <140°F. [RO 13548]

EPA originally intended that the alcohol exclusion apply only for solutions containing <24% ethanol. When they codified the regulatory language, however, the agency said “alcohol.” EPA clarified on June 1, 1990 that the term “alcohol” in the §261.21(a)(1) exclusion refers to any alcohol or combination of alcohols. [55 FR 22543] Additionally, “all aqueous wastes which are ignitable only because they contain alcohols (here using the term alcohol to mean any chemical containing the hydroxyl [–OH] functional group) are excluded from regulation.” [RO 11060] However, “if the alcohol is one of those alcohols specified in EPA hazardous waste codes F001–F005 and has been used for its solvent properties, the waste must be evaluated to determine if it should be classified as an F-listed spent solvent waste.” [RO 13548]

Ignitable solids

The second category of wastes exhibiting the ignitability characteristic is nonliquids that ignite due to friction, moisture absorption, or spontaneous chemical change and, once ignited, burn vigorously and persistently so as to create a hazard. [§261.21(a)(2)] The regulatory definition for ignitable solids sometimes causes confusion because the language is unclear. (We think it’s easier to call this group “solids” instead of “nonliquids.”) EPA has tried to clarify the definition by noting that two distinct criteria must both be met before a solid will be considered an ignitable waste: 1) it must be capable of ignition through friction, moisture absorption, or spontaneous ignition (e.g., a pyrophoric material); and 2) once ignited, it must burn vigorously and persistently so as to present a hazard. For example, titanium swarf may burn vigorously after ignition such that it poses a hazard, but since it is difficult to ignite, the material is not a D001 ignitable waste. Both criteria must be met. [RO 12089]

In the preamble to the May 19, 1980 rule establishing the ignitability characteristic, the agency tried to clarify the type of materials it wants to regulate under this category: “[EPA] has no intention of designating such things as wastepaper and sawdust to be hazardous and is only interested in capturing the small class of thermally unstable solids which are liable to cause fires through friction, absorption of moisture, or spontaneous chemical changes.” [45 FR 33108]

In a June 1, 1990 preamble [55 FR 22545], EPA provided additional guidance on this category of ignitable wastes:

“These wastes are typically generated on a sporadic basis in low volumes and are characterized as primarily inorganic solids or wastes containing reactive materials. Ignitable reactive materials include reactive alkali metals or metalloids (such as sodium and potassium) and calcium carbide slags. Most of these are very reactive with water and will generate gases that can ignite as the result of heat generated from the reaction with water. Other reactive ignitable solids in this subcategory include metals such as magnesium and aluminum that, when finely divided, can vigorously react with the oxygen in the air when ignited.

“There appears to be an overlap between wastes in this D001 subcategory and certain D003 (characteristic of reactivity) wastes. A close examination of the definitions in §261.21(a)(2) for ignitable wastes and §261.23(a)(2), (3), and [(4)] for reactive wastes reveals the distinction between these two groups. The key difference is in the definition of ignitable wastes, which states: ‘when ignited, burns vigorously and persistently.’ This phrase implies that the hazard is due primarily to the ignition potential rather than to the extreme reactivity.”

The regulations do not specify any test methods for determining the first criterion: if a waste is capable of ignition through friction, moisture absorption, or spontaneous ignition. Instead, the generator must evaluate this criterion based on “best engineering judgment” [RO 14285] and on “operational experience.” [RO 14176] The agency delineated the following issues that a generator can evaluate when applying best engineering judgment and operational experience as to the ignitability of solids; however, only the first one given below would be sufficient by itself for definitive classification of a solid as a D001 waste under §261.21(a)(2) [October 20, 2003; 68 FR 59940]:

  • Have there been landfill or other fires attributable to disposal of the solids?
  • Have the solids been observed emitting smoke during any phase of waste management?
  • Have the solids been packaged or transported with a DOT designation of pyrophoric or self-heating material?
  • Have the solids given a positive result in the DOT test for self-heating materials, as discussed in 49 CFR 173.124(b)(2) and 173.125(c)?
  • Is there any information on a safety data sheet (SDS) indicating the possibility of ignition due to friction, moisture absorption, or spontaneous ignition?
  • Have the solids ever been stored in special containers or under inert gas such as nitrogen?
  • Have the solids ever been stored in any other way so as to limit their exposure to the air, such as coating with oil or wetting with water?

The DOT regulations discuss spontaneously combustible and self-heating materials in 49 CFR 173.124(b) and reference test methods for materials liable to spontaneous combustion or self-heating in the UN Manual of Tests and Criteria. [RO 11935]

On January 3, 2008 [73 FR 486], EPA added Method 1050—Substances Likely to Spontaneously Combust to SW–846. The test procedures in Method 1050 are intended to identify two types of wastes with spontaneous combustion properties:

“Wastes (including mixtures and solutions, liquid or solid) which, even in small quantities, ignite within five minutes of coming in contact with air. These wastes are the most likely to spontaneously combust and are considered to have pyrophoric properties.

“Other solid wastes which, in contact with air and without an energy supply, are susceptible to self-heating. These wastes will ignite only when in large amounts (kilograms) and after long periods of time (hours or days) and are considered to have self-heating properties.”

This test method may be helpful to generators in determining whether a solid waste is capable of ignition through spontaneous chemical change.

EPA has approved Method 1030 in SW–846 for determining the second criterion: whether a material “burns so vigorously and persistently that it creates a hazard.” [June 13, 1997; 62 FR 32452] This method, which is appropriate for pastes, granular materials, solids that can be cut into strips, and powdery substances, is based on DOT’s burn-rate test. A 1,000°C flame from a Bunsen burner is used to ignite a 100-mm test strip or powder train of the material; if the material burns at a rate faster than 2.2 mm/sec (0.17 mm/sec for metals), the material is considered to have a positive result for ignitability according to the DOT regulations. However, the method is guidance only; its use is not required under §261.21(a)(2). As an alternative to using Method 1030, any valid, documented knowledge may be used to make this determination. [RO 14259]

It is important to note that, even if a solid tests positive using Method 1030, it is not automatically an ignitable hazardous waste under RCRA. Method 1030 only evaluates the second criterion of whether a material will burn vigorously and persistently; the first criterion, its capability of ignition through friction, moisture absorption, or spontaneous chemical change, must also be satisfied in order for the waste to be a D001 ignitable waste. However, if a generator’s waste does not test positive when using Method 1030 (i.e., an ignited test strip or powder train burns slower than the thresholds given in the test method), the generator should be able to use this knowledge to conclude that the waste solid is not ignitable per §261.21(a)(2).

EPA has noted that ASTM D4982-89 (Standard Test Method for Flammability Potential Screening Analysis of Waste) is not an appropriate method to determine if a solid is ignitable. [RO 14405]

Iron “sponge” is used to remove hydrogen sulfide from natural gas. It sometimes consists of redwood chips coated with hydrated ferric oxide. When spent, the sponge is removed from the absorption towers and placed on the ground. Due to contact with oxygen in the air, it begins to smolder; the smoldering continues until the sponge is reduced to ashes. Is the waste iron sponge ignitable at its point of generation (removal from the absorption towers)?

Possibly. The spent iron sponge is clearly not a liquid, so the §261.21(a)(2) criteria apply. Since the material will ignite due to moisture absorption and/or spontaneous ignition, the first criterion is satisfied. The generator must then use knowledge (e.g., the use of special fire-fighting techniques to extinguish a fire) or Method 1030 to determine if the smoldering material will burn vigorously and persistently so as to create a hazard. [RO 12115] Note, however, that even if ignitable, this waste may be excluded from hazardous waste regulation under the oil and gas exploration and production exclusion in §261.4(b)(5). [July 6, 1988; 53 FR 25454]

How should waste nitrocellulose filter fabric be prepared prior to testing using Method 1030? Should it be chopped into small pieces?

EPA recommends that materials such as nitrocellulose filter fabric be simply cut into long strips prior to Method 1030 testing. The agency does not recommend grinding, shredding, or chopping the sample into small pieces, because that would alter the form of the waste and greatly increase its surface area. [RO 14259]

Ignitability of solvent-contaminated rags/wipes

Sometimes, rags/wipes are contaminated with unlisted solvents (e.g., isopropyl alcohol). EPA has discussed how such wipes containing no free liquids (from the paint filter test and/or pressure filtration technique) may still be ignitable wastes. This may occur in two situations [RO 14285]:

  1. When a number of solvent-contaminated wipes are placed in a container, gravity (sometimes aided by compaction by plant personnel) causes solvent to be squeezed from the wipes. As a result, free solvent liquid may form on the container bottom. Any such free liquid in the container should be tested for flash point; if the flash point is <140°F, the entire waste in the container should be considered ignitable.
  2. When solvent-contaminated wipes are placed in an environment where oxygen is present, they may meet the ignitable solids criteria in §261.21(a)(2).

In either situation, the exclusions for wipes could still apply to the ignitable wipes if the conditions in §261.4(a)(26) or 261.4(b)(18) are met.

Ignitable compressed gases

To define this category of D001 wastes, EPA simply adopted DOT’s definition of “flammable” compressed gas. Until July 2006, the RCRA definition of an ignitable compressed gas in §261.21(a)(3) cited DOT’s regulations at 49 CFR 173.300, which has been an obsolete DOT citation since 1990. To fix that problem, EPA issued a technical correction on July 14, 2006. [71 FR 40254] However, instead of replacing the obsolete reference in §261.21(a)(3) with correct references to DOT’s current regs, the agency replaced the out-of-date reference with the complete text of the definition from the 1980 version of DOT’s regulations (i.e., the DOT definition that was in effect at the time the RCRA regs were first issued).

So today, the RCRA regs define an ignitable compressed gas as a compressed gas that 1) is flammable when in a mixture of 13% or less with air (i.e., its lower flammability limit is 13% or less), or 2) has a flammable range with air of more than 12% (i.e., the difference between its upper and lower flammability limit is greater than 12 percentage points) regardless of the lower flammability limit. All percentages are based on volume at 68°F and 1 atm absolute pressure.

That 1980 definition of a flammable compressed gas is basically the same as DOT’s current one in 49 CFR 173.115. However, the old DOT regulations that are now in the RCRA regs include Bureau of Explosives test methods to determine flammability, while DOT’s new regulations specify ASTM E681-85 (Standard Test Method for Concentration Limits of Flammability of Chemicals).

Examples of D001 ignitable compressed gases are cylinders of waste propane or acetylene.

Oxidizers

As with ignitable compressed gases, EPA based its regulatory definition of a D001 oxidizer on DOT’s definition. However, the RCRA definition of an oxidizer in §261.21(a)(4) referenced DOT’s regulations at 49 CFR 173.151, which has been an obsolete DOT citation since 1990. When EPA corrected this problem on July 14, 2006 [71 FR 40254], the agency replaced the out-of-date reference with the complete text of the oxidizer definition from the 1980 version of DOT’s regulations (i.e., the DOT definition that was in effect at the time the RCRA regs were first issued).

That 1980 definition includes a material “that yields oxygen readily to stimulate the combustion of organic matter.” The current DOT definition in 49 CFR 173.127 is similar: a Hazard Class 5.1 oxidizer is “a material that may, generally by yielding oxygen, cause or enhance the combustion of other materials.” However, DOT’s current regulatory language includes test methods for quantifying such a designation—the old DOT regulations that are now in the RCRA regs give none.

Chlorates, permanganates, inorganic peroxides, and nitrate compounds are all examples of oxidizers that are hazardous for ignitability when they become wastes, because they meet DOT’s definition of an oxidizer.

On January 3, 2008 [73 FR 486], EPA added Method 1040—Test Method for Oxidizing Solids to SW–846. The test procedures in Method 1040 are intended to evaluate the relative oxidizing hazard posed by wastes that are physically solid, including granular and other materials that can be formed into a conical pile. The method is based on a conical pile-type burning test method adapted from the UN regulations and classification procedures, and it provides a qualitative means to measure the potential of a physically solid waste to increase the burning rate or burning intensity of a combustible substance. This test method was specifically developed to illustrate the oxidizer properties of materials and thus may be helpful to generators in determining whether a solid waste is capable of stimulating the combustion of organic matter per §261.21(a)(4).

The July 14, 2006 rule also clarified in a Note 4 to §261.21 that organic peroxides (which are currently defined by DOT as Hazard Class 5.2 in 49 CFR 173.128) are a type of oxidizer. Therefore, these materials will also be identified as D001 when they become wastes. The organic peroxide table [found in 49 CFR 173.225(c)] may be used for the classification and packaging of organic peroxides. This table, although not exhaustive, identifies common organic peroxides found in industry. By referencing the organic peroxide table, one can determine if a waste is an organic peroxide, thus warranting the D001 waste code. For example, in the organic peroxide table, methyl ethyl ketone peroxide is listed three times. The listings are concentration- and diluent-dependent. All three listings identify the material as an organic peroxide, so no matter which description is selected by the generator, it will be classified as 5.2, which warrants the D001 waste code when this material is intended for disposal.

There is a possible overlap between ignitable oxidizers (which would be D001) and reactive oxidizers (which would be D003). EPA noted in RO 51434 that an oxidizer that reacts violently should be considered a D003 reactive waste; on the other hand, an oxidizer which reacts in a milder manner should be considered a D001 ignitable oxidizer.

Probably the easiest way to determine if a waste is a D001 oxidizer is to look up the material on DOT’s hazardous materials table at 49 CFR 172.101. Column (3) on this table identifies the Hazard Class of each material; a Hazard Class of 5.1 or 5.2 indicates that the material is a DOT oxidizer. We don’t profess to be knowledgeable about all DOT requirements; therefore, our bias is to consider all 5.1 and 5.2 materials (when they become wastes) to be D001 wastes, unless advised otherwise by an authorized regulatory agency or a DOT expert. However, if a generator stops here, the classification is not complete, for Column (3) in the hazardous materials table identifies only the primary hazard associated with a given hazardous material. For a complete classification, the generator must also reference Column (6), which identifies the primary and subsidiary hazards associated with a given hazardous material.

For example, should spent nitric acid be coded D001 due to its oxidizer potential? EPA has given peripheral guidance noting that the D001 code may apply for nitric acid in RO 11480. The answer depends on the concentration of the nitric acid being disposed. By referencing the DOT hazardous materials table, if the nitric acid concentration is 65–70 percent, the subsidiary hazard found in Column (6) is 5.1, thus warranting the D001 waste code when disposed. If the concentration of the nitric acid is less than or equal to 65 percent, the oxidizer hazard is not present and the D001 waste code would not be justified.

A bath containing inorganic peroxides is used to clean brass and other copper alloys prior to plating, lacquering, or other finishing activities. Could the spent baths be D001 ignitable wastes?

Yes. Because the baths contain inorganic peroxides, they could meet the definition of a DOT oxidizer. However, once the hydrogen peroxide has been chemically decomposed, the wastes would no longer exhibit the ignitability characteristic due to the presence of an oxidizer. [RO 11854]

Potassium permanganate is sometimes used as a bleach in the garment industry. When spent, can the material be disposed in a nonhazardous waste landfill?

Yes. “Since spent permanganate materials are already reduced, they are not likely to be powerful oxidizers and, therefore, are not likely to exhibit a hazardous waste characteristic.” [RO 11628]


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