Frequent Questions About Hazardous Waste Identification
On this page:
- Are alcoholic beverages regulated as hazardous waste when they exhibit the characteristic of ignitability?
- Do the regulations allow dilution of an ignitable or characteristic waste to remove the characteristic?
- Does a waste derived from a hazardous waste listed solely for exhibiting a characteristic of ignitability, corrosivity, and/or reactivity remain a hazardous waste when it no longer exhibits a hazardous waste characteristic?
- What RCRA hazardous wastes are classified as "acute" hazardous wastes?
- Is an as-generated waste (spent carbon from the treatment of wastewater containing explosives) still considered a RCRA hazardous waste since it meets the listing description of K045 even if it is later decharacterized? If so, would this waste be subject to the land disposal restrictions (LDR)?
- What are elementary neutralization units?
- Is hazardous waste treatment permissible in an elementary neutralization unit?
- Would hazardous waste listings apply to the remaining solvent (e.g., paint thinner) removed from spray cans?
- Do the spent solvent listings in Section 261.31 apply to solvent constituents used as ingredients in the formulation of a commercial chemical product (CCP)?
- Does the U223 hazardous waste code apply to virgin toluene diisocyanate (TDI) that has been neutralized to remove the reactivity characteristic?
- Why is it that environmental media and debris contaminated with petroleum product released from an underground storage tank (UST) is not regulated as a hazardous waste?
- Are clothing and gloves used as personal protective equipment (PPE) during hazardous waste management activities regulated as hazardous waste?
- How is contaminated environmental media regulated under the contained-in policy?
- If you generate hazardous soil and move it to another place at the same site, is that considered disposal? Would you have to meet applicable treatment standards before placement?
- Is investigation-derived waste containing tetrachloroethylene (otherwise known as perchloroethylene or PCE) generated from soil found beneath a former dry-cleaner business a listed hazardous waste?
- What RCRA hazardous waste code would apply to soil contaminated with cyanide? We suspect that the soil may be contaminated as a result of an electroplating operation that generates F007 and F009 waste.
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Are alcoholic beverages regulated as hazardous waste when they exhibit the characteristic of ignitability?
Aqueous solutions containing less than twenty-four percent alcohol by volume are excluded from the characteristic of ignitability (Section 261.21(a)(1)). EPA originally intended for the alcohol exclusion to exempt alcoholic beverages and some types of latex paints that exhibit low flash points due to the alcohol content, but do not sustain combustion because of the high water content (45 FR 33084, 33108; May 19, 1980). Nevertheless, the alcohol exclusion is not limited to alcoholic beverages or paints. The exclusion applies to all aqueous solutions containing less than twenty-four percent alcohol, even if additional non-alcoholic components are present. The term "alcohol" refers to any alcohol or combination of alcohols (55 FR 22520, 22543; June 1, l990). However, if the alcohol has been used for solvent properties and is one of the alcohols specified in EPA hazardous waste codes F001-F005, the waste must be evaluated to determine if it should be classified as an F-listed spent solvent waste (Monthly Call Center Report Question; July 1992 (RCRA Online #13548)).
Additional guidance on the alcohol exclusion is available in the following documents:
Memo, Skinner to Walter; February 26, 1985 (RCRA Online #11060)
Monthly Call Center Report Question; August 1984 (RCRA Online #12274)
Do the regulations allow dilution of an ignitable or characteristic waste to remove the characteristic?
No generator, transporter, handler, or owner or operator of a Treatment, Storage and Disposal Facility (TSDF) shall dilute a hazardous waste as a substitute for adequate treatment.
However, dilution of wastes that are hazardous only because they exhibit a characteristic and are subsequently discharged under the Clean Water Act or Safe Drinking Water Act (e.g., Class I underground injection well) is not impermissible, unless a treatment method other than DEACT is specified.
In all cases, the Agency has determined that for non-toxic hazardous characteristic wastes, it should not matter how the characteristic property is removed so long as it is removed. Thus, dilution is an acceptable treatment method for such wastes.
Any solid waste is not a hazardous waste if it does not exhibit any of the characteristics of hazardous waste identified in 40 CFR Part 261 Subpart C. However, wastes that exhibit a characteristic at the point of generation may still be subject to the LDR requirements in Part 268, even if they no longer exhibit a characteristic at the point of land disposal.
Characteristic wastes that are exempt from the dilution prohibition and which are managed and disposed of on-site, are not subject to the full Section 268.7 requirements for waste analysis and record keeping.
References: 40 CFR Section 268.3(a)
40 CFR Section 268.3(b); 55 FR 22520, 22532, June 1, 1990
40 CFR Section 261.3(d)
Monthly Call Center Report Question, October 2002 (RCRA Online #14638)
66 FR 27266, 27269, May 16, 2001
The Hazardous Waste Identification Process
40 CFR Section 268.7(a)(7)
Does a waste derived from a hazardous waste listed solely for exhibiting a characteristic of ignitability, corrosivity, and/or reactivity remain a hazardous waste when it no longer exhibits a hazardous waste characteristic?
A solid waste derived from a hazardous waste listed solely for exhibiting a characteristic of ignitability, corrosivity, and/or reactivity is not a hazardous waste when it no longer exhibits any characteristic of hazardous waste (40 CFR Section 261.3(g)(2)(ii)). However, a waste listed solely for exhibiting the characteristic of ignitability, corrosivity, and/or reactivity that exhibits the characteristic at the point of generation and subsequently loses the characteristic is still subject to the land disposal restrictions requirements in Part 268 (66 FR 27266; May 16, 2001).
What RCRA hazardous wastes are classified as "acute" hazardous wastes?
Hazardous wastes listed in accordance with the criteria in 40 CFR Section 261.11(a)(2) are designated as "acute" hazardous wastes. Acute hazardous wastes are assigned the hazard code (H) (Section 261.30). Specifically, a waste is classified as an acute hazardous waste if it is any P-listed waste (Section 261.33) or one of the following F-listed wastes: F020, F021, F022, F023, F026, and F027 (Section 261.31).
Is an as-generated waste (spent carbon from the treatment of wastewater containing explosives) still considered a RCRA hazardous waste since it meets the listing description of K045 even if it is later decharacterized? If so, would this waste be subject to the land disposal restrictions (LDR)?
The as-generated waste would not be considered a hazardous waste even though it meets the listing description for K045. A waste listed solely for the characteristic of ignitability, reactivity, and/or corrosivity is excluded from regulation as a hazardous waste once it no longer exhibits a characteristic of hazardous waste (Section 261.3(g)(1)). The same rationale applies when a waste meets such a listing description but does not exhibit a characteristic of hazardous waste at the point of generation. In the Hazardous Waste Identification Rule, EPA stated that extending this exclusion to as-generated wastes that do not exhibit a characteristic of hazardous waste remains protective of human health and the environment (66 FR 27266, 27283; May 16, 2001). Additionally, the as-generated waste would not be subject to the LDR requirements in Part 268 (51 FR 40572, 40620; November 7, 1986). EPA has clarified that when a waste has been listed solely because it exhibits a characteristic of ignitability, corrosivity and/or reactivity and that waste does not exhibit any hazardous waste characteristic at the point of generation, then that waste is not subject to the LDR requirements (66 FR 27266, 27269; May 16, 2001). If, however, the waste exhibits a characteristic at the point of generation and subsequently becomes decharacterized, then it would be subject to the LDR requirements (Section 261.3(g)(3)).
What are elementary neutralization units?
Elementary neutralization units are tanks, tank systems, containers, transport vehicles, or vessels used for neutralizing wastes that are hazardous only because they exhibit the corrosivity characteristic or because they are listed solely for the characteristic of corrosivity (Section 260.10). A tank, tank system, container, transport vehicle, or vessel that meets the definition of an elementary neutralization unit is exempt from permitting requirements under RCRA Subtitle C (Sections 264.1(g)(6), 262.1(c)(2), and 270.1(c)(2)(v)). In addition, generators managing hazardous waste immediately upon generation in an on-site elementary neutralization unit are not required to count those wastes toward their monthly generator status (Section 262.1(c)(2)).
Is hazardous waste treatment permissible in an elementary neutralization unit?
An elementary neutralization unit is a device which:
(1) is used for neutralizing wastes that are hazardous only because they exhibit the corrosivity characteristic defined in Section 261.22, or they are listed in Part 261 Subpart D only for this reason; and
(2) meets the definition of tank, tank system, container, transport vehicle, or vessel (Section 260.10).
Treatment means any method, technique, or process, including neutralization, designed to change the physical, chemical, or biological character or composition of any hazardous waste so as to neutralize such waste, or so as to recover energy or material resources from the waste, or so as to render such waste non-hazardous, or less hazardous; safer to transport, store, or dispose of; or amenable for recovery, amenable for storage, or reduced in volume (40 CFR Section 260.10). Some forms of treatment are not regulated under RCRA, including treatment of hazardous wastes in an elementary neutralization unit.
Would hazardous waste listings apply to the remaining solvent (e.g., paint thinner) removed from spray cans?
The unused solvent removed from the spray can may meet a hazardous waste listing. If the remaining solvent in the spray can is located on either the P list or the U list in Section 261.33(e) or (f), the residue could be a listed hazardous waste. Specifically, Section 261.33(b) states that, "any residue remaining in a container or in an inner liner removed from a container that has held any commercial chemical product or manufacturing chemical intermediate having the generic name listed in paragraphs (e) or (f) of this section, unless the container is empty as defined in Section 261.7(b) of this chapter" is a hazardous waste.
However, if the residue is not on the P list or the U list, it may still be hazardous if it exhibits any of the characteristics of a hazardous waste as defined in Part 261, Subpart C. It is the responsibility of the generator to make this determination. The unused solvent removed from the spray cans would not be classified as a spent solvent waste as listed in Section 261.31. The solvent waste F-listings apply to spent solvents, which are particular chemicals used for their solvent properties, that is, to solubilize, dissolve or mobilize other constituents, but are no longer useable as solvents (50 FR 53315, 53316: December 31, 1985). The product paint thinner remaining in the aerosol can was not used as a solvent, nor was it spent because it was never used in the first place. Therefore, the spent solvent F-listings would not apply to the discarded product.
Do the spent solvent listings in Section 261.31 apply to solvent constituents used as ingredients in the formulation of a commercial chemical product (CCP)?
Process wastes containing solvents where the solvent is used as an ingredient in the formulation of a CCP do not fall within the scope of the spent solvent listings. Additionally, the products themselves do not meet the listings (50 FR 53315, 53316; December 31, 1985). Thus, when unused solvent is added to a product (e.g., paint or ink) as an ingredient, any unused product being disposed of would not carry an F listing. However, if the solvent served as the sole active ingredient for the function of the product (e.g., solvent), then the disposed unused product may be a P- or U-listed hazardous waste. (Call Center Monthly Report Question; June 1997 (RCRA Online 14109)).
The solvent constituents listed in Section 261.31 apply to hazardous wastes when they are used as solvents and have become contaminated with physical or chemical impurities and are no longer fit for use without being regenerated, reclaimed, or otherwise re-processed. Solvent constituents are considered used as a solvent when they are used for their solvent properties (i.e., to solubilize (dissolve) or mobilize other constituents) (50 FR 53315, 53316; December 31, 1985). For example, solvents used as cleaning or degreasing agents, mediums for chemical reactions, extraction agents, and diluents are covered under the F001 though F005 listings in Section 261.31 (Memo, Straus to Harvey; May 2, 1986 (RCRA Online 11151)). Opens a New Window.
Additional guidance regarding the spent solvent hazardous waste listings is available in the following documents:
Memo, Shapi to Dolce; March 1, 1994 (RCRA Online 11815)
Memo, Bussard to Wilson; June 14, 1990 (RCRA Online 11523)
Memo, Lowrance to Diehn; May 3, 1990 (RCRA Online 11513)
Memo, Barnes to Stockli; April 12, 1989 (RCRA Online 13273)
Memo, Barnes to Moretta; December 6, 1988 (RCRA Online 11384)
Memo, Barnes to Lindberg; May 5, 1988 (RCRA Online 11349)
Memo, Sales to Czigler; May 20, 1987 (RCRA Online 11249)
Memo, Straus to Skoufis; March 6, 1987 (RCRA Online 11224)
Memo, Straus to Hemker; February 19, 1987 (RCRA Online 11220)
Memo, Straus to McAdams; August 4, 1986 (RCRA Online11169)
Does the U223 hazardous waste code apply to virgin toluene diisocyanate (TDI) that has been neutralized to remove the reactivity characteristic?
The U223 waste code may apply to toluene diisocyanate (TDI) if it is an unused commercial chemical product (CCP) that is being discarded. A CCP is a substance that consists of the commercially pure grade of a chemical listed in 40 CFR Section 261.33, any technical grades of the chemical, and all formulations in which the chemical is the sole active ingredient (Section 261.33(d))(54 FR 31335, 31336; July 28, 1989).
The pure form of a chemical is a formulation consisting of one hundred percent of that chemical. The technical grade of a chemical is a formulation in which the chemical is almost one hundred percent pure, but contains minor impurities (Memo, Lowrance to Wayland; May 3, 1988 (RCRA Online #11348)).
A chemical is the sole active ingredient in a formulation if that chemical is the only active ingredient serving the function of the formulation. However, if a formulation contains more than one active ingredient, the formulation would not fall within the scope of the listing in Section 261.33, regardless of whether only one or both of the active ingredients are listed (Monthly Call Center Report Question; March 1992 (RCRA Online #13530)).
A mixture of a solid waste and a hazardous waste listed solely for the characteristic of ignitability, corrosivity, or reactivity is no longer a hazardous waste if the mixture does not exhibit the hazardous characteristic (Section 261.3(g)(2)(i)). The same rationale applies when a waste meets a listing description, but does not exhibit a characteristic of hazardous waste at the point of generation (Monthly Call Center Report Question; October 2002 (RCRA Online #14638)).
There are currently twenty-nine wastes codes within the RCRA program listed solely for the characteristic of ignitability, corrosivity, or reactivity (66 FR 27266, 27283; May 16, 2001). However, U223 is not one of these twenty-nine wastes codes because it was not listed solely for exhibiting the characteristic of reactivity. It was listed because it is both reactive and toxic (Section 261.33(f)). Therefore, the U223 waste code would apply to the discarded toluene diisocyanate if it is an unused CCP even when its reactive properties have been removed or neutralized.
Additional guidance regarding the applicability of P and U listed waste codes is available in the following documents:
Monthly Call Center Report Question; August 1996 (RCRA Online #14012)
Memo, Dellinger to Smith; March 18, 2003 (RCRA Online #14654)
Memo, Barnes to Mastalerz; August 21, 1989 (RCRA Online #11459)
Memo, Barnes to Fox; May 19, 1988 (RCRA Online #11350)
Why is it that environmental media and debris contaminated with petroleum product released from an underground storage tank (UST) is not regulated as a hazardous waste?
The reason for the different regulatory requirements is that the EPA created a specific hazardous waste exemption for the petroleum-contaminated media and debris caused by leaking USTs because of potentially significant impacts related to the Agency's comprehensive program to prevent leaking underground storage tanks, under Subtitle I of RCRA, including impacts to the cleanup of USTs that have leaked in the past.
Petroleum contaminated media and debris is excluded from the definition of hazardous waste when the media or debris, such as soil and groundwater, is generated from petroleum UST corrective action activities and fails the toxicity characteristic for hazardous waste codes D018 through D043 (Section 261.4(b)(10)). At the time of promulgation of the final Toxicity Characteristic (TC) rule, EPA made a determination to temporarily defer applicability of the TC rule to media and debris contaminated with petroleum from USTs subject to the corrective action requirements of Subtitle I of RCRA. EPA had little information regarding the full impact of the TC rule on UST cleanups; however, a preliminary assessment indicated that the number of UST cleanup sites and the amount of media and debris at each site that would exhibit the toxicity characteristic would be extremely high. EPA reasoned that subjecting all, or even a portion, of these sites to Subtitle C requirements could overwhelm the hazardous waste permitting program and the capacity of existing hazardous waste treatment, storage, and disposal facilities. In addition, imposition of the requirements could delay UST cleanups significantly (58 FR 8504, 8504; February 12, 1993).
On December 24, 1992, EPA proposed a similar exclusion for contaminated media and debris contaminated by petroleum products from non-UST sources (57 FR 61542), however, EPA never finalized that proposal. EPA later stated in the HWIR-media proposal that finalization was unnecessary because a final HWIR-media rule would solve the problems that the non-UST TC suspension was intended to address (63 FR 65873, 65931; November 30, 1998).
It is important to note that a generator must still determine if petroleum contaminated media and debris is hazardous for the hazardous waste codes D001 through D017 (Memo, Lowrance to Bevington; November 9, 1990 (RCRA Online #11569)). In addition, the definition of an UST includes those tanks or combinations of tanks whose volume, including the volume of underground connected piping, is ten percent or more beneath the surface of the ground (Section 280.12). Any tank that does not meet this definition is not a UST for the purposes of Part 280, would not be subject to comprehensive requirements for the reporting and cleanup of soil and groundwater contaminated from USTs, and thus would not qualify for the exclusion in Section 261.4(b)(10).
See Underground Storage Tanks for more information.
Additional guidance regarding the petroleum contaminated media and debris exclusion in Section 261.4(b)(10) is available in the following documents:
Monthly Call Center Report Question; January 1998 (RCRA Online #14316 )
Monthly Call Center Report Question; November 1994 (RCRA Online #13711)
Monthly Call Center Report Question; October 1990 (RCRA Online #13409 )
Are clothing and gloves used as personal protective equipment (PPE) during hazardous waste management activities regulated as hazardous waste?
Personal protective equipment (PPE), including contaminated clothing and similar debris, are not solid wastes but may be regulated under the contained-in policy. Under the contained-in policy, the PPE contains hazardous waste if it exhibits a characteristic or contains listed hazardous waste. If contamination cannot be removed, PPE must be treated to land disposal restrictions (LDR) treatment standards prior to disposal (Memo, Lowrance to Fields; January 3, 1989 (RCRA Online #11387)).
Additional guidance is available in the following documents:
Memo, Bussard to Colby; July 27, 1997 (RCRA Online #14095)
Memo, Lowrance to Ullrich; June 14, 1990 (RCRA Online #11524)
How is contaminated environmental media regulated under the contained-in policy?
The contained-in policy is a more flexible version of the mixture and derived-from rules that applies to contaminated environmental media. EPA uses the term environmental media to describe soil, sediments, and ground water (61 FR 18780, 18783; April 29, 1996). Environmental media are usually contaminated through accidental spills of hazardous waste or spills of product chemicals that, when spilled, become hazardous wastes. Environmental media is not inherently a solid or hazardous waste and, generally, is not subject to regulation under RCRA. Environmental media that are contaminated can become subject to regulation under RCRA if they “contain” hazardous waste (Management of Remediation Waste Under RCRA; October 14, 1998 (RCRA Online #14291)).
EPA’s contained-in policy states that environmental media contaminated with a hazardous waste must be managed as if they were hazardous wastes until they no longer contain the listed waste, no longer exhibit a characteristic, or are delisted. In order for environmental media contaminated with a listed waste to no longer be considered hazardous, the handler of those media must demonstrate to EPA's or the authorized State's satisfaction that the media no longer poses a sufficient health threat to merit RCRA regulation. EPA has not issued guidelines as to when or at what levels environmental media contaminated with hazardous wastes are no longer considered to contain those hazardous wastes. The levels for media are most appropriately determined on a site-specific basis by the EPA Region or authorized State overseeing the cleanup of such materials under Superfund response actions or RCRA corrective action. These levels are generally determined by the implementing agency according to risk (57 FR 958, 986; January 9, 1992).
Additional guidance on the contained-in policy is available in the following documents:
Memo, Shapiro to Wright; September 15, 1995 (RCRA Online #11948)
Memo, Lowrance to Warren; October 15, 1992 (RCRA Online #13568)
Memo, Lowrance to Ely; March 26, 1991 (RCRA Online #11593)
If you generate hazardous soil and move it to another place at the same site, is that considered disposal? Would you have to meet applicable treatment standards before placement?
Land disposal means placement in or on the land, except in a corrective action management unit or staging pile, and includes but is not limited to, placement in a landfill, surface impoundment, waste pile, injection well, land treatment facility, salt dome formation, salt bed formation, underground mine or cave, or placement in a concrete vault or bunker intended for disposal purposes.
Removal of restricted waste from a unit and subsequent placement of the waste, either back into the unit or into another unit, is subject to the land disposal restrictions. In situ treatment or movement of waste within the same unit does not constitute "placement" and does not subject the waste to the land disposal restrictions.
The placement concept is also used in the Area of Contamination (AOC) Policy. Because a designated AOC is equated to a RCRA land-based unit, consolidation and in situ treatment of hazardous waste within an AOC does not create a new point of hazardous waste generation for purposes of RCRA.
Hazardous wastes placed into land disposal units after the effective date are subject to the prohibitions, but wastes disposed prior to the applicable effective date do not have to be removed or exhumed for treatment. If, however, wastes subject to land disposal restrictions are removed from either a storage or land disposal unit after the effective date, subsequent placement of such wastes in or on the land would be subject to the restrictions and treatment provisions.
References:
40 CFR Section 268.2(c)
Memo, Weddle to Vaille, July 19, 1988 (RCRA Online #11354)
Memo, Fields and Herman to RCRA Senior Policy Managers, October 14, 1998 (RCRA Online #14291)
51 FR 40572, 40577, November 7, 1986
Is investigation-derived waste containing tetrachloroethylene (otherwise known as perchloroethylene or PCE) generated from soil found beneath a former dry-cleaner business a listed hazardous waste?
PCE contaminated media may be regulated as listed hazardous waste because contaminated environmental media is subject to regulation when it contains hazardous waste. Generally, EPA considers contaminated media to contain hazardous waste when it exhibits a characteristic of hazardous waste, or when it is contaminated with concentrations of hazardous constituents from listed hazardous waste that are above health-based levels (Management of Remediation Waste Under RCRA, EPA530-F-98-026). In addition, spent PCE used in dry cleaning is classified as F002 when the spent solvent formulation meets the ten percent (by volume) criterion in the listing (Call Center Monthly Report Question; October 1992, RCRA Online #13565). Therefore, contaminated media that contains spent PCE meeting the F002 listing description in Section 261.31 is regulated as F002.
A generator must know the source and the before use concentration of PCE in order to determine if the F002 listing applies. If the source of the PCE is from a product spill (e.g., unused solvent), it could be a U210 listed waste. A facility owner or operator must make a good faith effort to determine if a material is a listed hazardous waste. However, if an owner or operator cannot make such a determination because documentation regarding a source of contamination, contaminant, or waste is unavailable or inconclusive, the owner or operator may assume the source, contaminant, or waste is not a listed hazardous waste and, provided the material in question does not exhibit a characteristic of hazardous waste, that RCRA requirements do not apply (Management of Remediation Waste Under RCRA, EPA530-F-98-026).
Furthermore, media that becomes contaminated with hazardous waste must be managed as if it were hazardous waste until it no longer exhibits a hazardous waste characteristics or no longer contains the listed waste. EPA believes that such levels for contaminated media are most appropriately determined on a site-specific basis by the EPA Region (or authorized state) overseeing cleanup of such materials (Management of Remediation Waste Under RCRA, EPA530-F-98-026).
Additional guidance regarding the applicability of the F002 hazardous waste code is available in the following documents:
Call Center Monthly Report Question; May 1991 (RCRA Online #13469)
Memo, Lowrance to Wassersug; September 22, 1989 (RCRA Online #11470)
Additional guidance regarding contaminated media is available in the following documents:
Memo, Fields and Herman to RCRA/CERCLA Senior Policy Managers; October 14, 1998 (RCRA Online #14291)
Memo, Shapiro to Wright, September 15, 1995 (RCRA Online #11948)
Memo, Lowrance to Ely; March 26, 1991 (RCRA Online #11593)
Memo, Cannon to Jorling; June 19, 1989 (RCRA Online #11434)
What RCRA hazardous waste code would apply to soil contaminated with cyanide? We suspect that the soil may be contaminated as a result of an electroplating operation that generates F007 and F009 waste.
Contaminated environmental media can become subject to regulation if they "contain" hazardous waste. EPA generally considers contaminated media to contain hazardous waste: when they exhibit a characteristic of hazardous waste, or when they are contaminated with concentrations of hazardous constituents from listed hazardous waste that are above health-based levels.
Environmental media that contain listed hazardous waste must be managed as hazardous waste as long as they contain listed wastes.
Media that are contaminated with hazardous waste must be managed as if they were hazardous waste until they no longer "contain" the listed waste. EPA believes that such levels for media are most appropriately determined on a site-specific basis by the EPA Region (or authorized State) overseeing cleanup of such materials.
A waste which contains a listed waste remains a hazardous waste until it is delisted.
References:
Memo, Fields and Herman to RCRA/CERCLA Senior Policy Managers, October 14, 1998 (RCRA Online #14291)
Memo, Shapiro to Wright, September 15, 1995 (RCRA Online #11948)
57 FR 958, 986, January 9, 1992
61 FR 18780, 18785, April 29, 1996