Opinion for the court filed by Circuit Judge BUCKLEY.
Petitioners raise numerous challenges to the “mixture” and “derived-from” rules promulgated by the Environmental Protection Agency under authority of Subtitle C of the Resource Conservation and Recovery Act of 1976 (“RCRA”), 42 U.S.C. §§ 6901-6992k (1988 & Supp. IV 1992). We do not address these challenges, however, because we conclude that' subsequent congressional action has rendered the dispute moot. Petitioners American Mining Congress and The Fertilizer Institute also challenge the so-called “Be-vill mixture rule,” promulgated under the same authority, which we vacate in part.
I. BackgRound
RCRA provides a comprehensive scheme for handling solid wastes. As part of this regime, Subchapter III, 42 U.S.C. §§ 6921-6939b (1988 & Supp. IV 1992) (“Subtitle C”), subjects hazardous wastes to stringent cradle-to-grave regulation. The statute defines “hazardous waste” as
a solid waste, or combination of solid wastes, which because of its quantity, concentration, or physical, chemical, or infectious characteristics may—
(A) cause, or significantly contribute to an increase in mortality or an increase in serious irreversible, or incapacitating reversible, illness; or
(B) pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of, or otherwise managed.
42 U.S.C. § 6903(5) (1988). Subtitle C also established a two-step process for the identification of hazardous wastes: The EPA would first promulgate criteria for identifying the “characteristics” of hazardous waste, “taking into account toxicity, persistence, and degradability in nature, potential for accumulation in tissue, and other related factors such as flammability, corrosiveness, and other hazardous characteristics.” Id. § 6921(a) (1988). Then, on the basis of those criteria, the EPA would “promulgate regulations identifying the characteristics of hazardous waste, and listing particular hazardous wastes (within the meaning of section 6903(5) of this title), which shall be subject to the provisions of [Subtitle C].” Id. § 6921(b)(1).
Pursuant to this mandate, the EPA issued proposed rules in 1978. 43'Fed.Reg. 58,946 (1978). In that proposal, the EPA stated that it would identify hazardous wastes on the basis of the following characteristics: ig-nitability, corrosivity, reactivity and toxicity. 43 Fed.Reg. at 58,950, 58,955-57. Wastes displaying any of these characteristics were to be listed, as were wastes that independently satisfied the statutory definition of *581 “hazardous waste” contained in 42 U.S.C. § 6903(5). 43 Fed.Reg. at 58,955, col. 2. A listed waste would remain subject to Subtitle C regulation until it was certified to the EPA that the waste was “non-hazardous according to the results of each characteristic or property tested.” 43 Fed.Reg. at 58,953, col. 3.
The EPA issued its final rule on May 19, 1980, in which it published a list of some 400 hazardous wastes. 45 Fed.Reg. 33,084, 33,-122-27 (1980). The final rule also promulgated the “mixture” and “derived-from” rules. The mixtee rule provided that a solid waste would be treated as hazardous if “[i]t is a mixture of solid waste and one or more [listed] hazardous wastes.... ” Id. at 33,119, col. 3. The derived-from rule provided that
[a]ny solid waste generated from the treatment, storage, or disposal of a hazardous waste, including any sludge, spill residue, ash, emission control dust or leachate (but not including precipitation run-off) is a hazardous waste.
45 Fed.Reg. at 33,120, col. 1. Thus a substance that was mixed with a listed hazardous waste or derived from a hazardous waste was to be regulated as a hazardous waste regardless of whether the mixture or derivative actually “[p]ose[d] a substantial present or potential hazard to human health or the environment....” 42 U.S.C. § 6903(5).' Any mixture or derived-from waste, however, could escape Subtitle C regulation through a “delisting” process. See 45 Fed.Reg. at 33,-116, col. 3 (waste may be delisted if demonstrated that it is non-hazardous “based on the results of specific tests for each of the hazardous properties for which the waste was listed”).
The initial promulgation of the mixture and derived-from rules was challenged on both substantive and procedural grounds. On December 6, 1991, we vacated both rules because the EPA had “entirely failed to comply with [the Administrative Procedure Act’s] notice-and-comment requirements_”
Shell Oil Co. v. EPA
On March 3, 1992, the EPA issued an “interim final rule,” reinstating the vacated mixture and derived-from rules under authority of the APA’s “good cause” exception, 5 U.S.C. § 553(b)(3)(B), which permits the issuance of a rule without notice and prior opportunity for comment on a finding that such are “impractical, unnecessary, or contrary to the public interest.” 57 Fed.Reg. 7,628, 7,628-29 (1992). In doing so, the ,EPA sought to obtain “the time to sort through more fully the implications of alternative regulatory approaches and understand the scope and effect of current Subtitle C rules.” 57 Fed.Reg. at 7,630, col. 3. The EPA promised to publish options for modifying or replacing the rules by April 28,1992; and it included a provision terminating the interim final rules on April 28, 1993 (“sunset provision”). Id.
The promised revisions were issued on May 20, 1992. These included a “Hazardous Waste Identification Rule” (“HWIR”) that would effect “modifications to the RCRA regulatory framework which will address over-regulatory situations created by the ‘mixture’ and ‘derived-from’ rules.” 57 Fed.Reg. 21,-450, 21,452, col. 1 (1992). In the HWIR, the EPA conceded that the mixture and derived-from rules were overinclusive, resulting in a regime where “millions of tons of mixtures and derived-from residuals that must be managed as hazardous waste [under Subtitle C] because of their history (ie., what they were mixed with or derived-from) may actually pose quite low hazards.” Id. at 21,451, col. 3.
Five months later, on October 6, 1992, Congress adopted an amendment to an EPA appropriations bill that reads as follows:
EPA shall promulgate revisions to paragraphs (a)(2)(iv) [the mixture rule] and (c)(2)(i) [the derived-from rule] of 40 CFR 261.3, as reissued on March 3, 1992, by October 1, 1994, but any revision to such paragraphs shall not be promulgated or become effective prior to October 1, 1993. Notwithstanding paragraph (e) of 40 CFR 261.3 [the “sunset provision”], as reissued on March 3,1992, paragraphs (a)(2)(iv) and (c)(2)(i) of such regulations shall not be terminated or withdrawn until revisions are promulgated and become effective in *582 accordance with the preceding sentence. The deadline of October 1, 1994 shall be enforceable under section 7002 of the Solid Waste Disposal Act.
Pub.L. No. 102-389, 106 Stat. 1571, 1602 (Oct. 6, 1992) (“Chafee Amendment”). The EPA contends that this amendment codifies the mixture and derived-from rules, mooting petitioners’ challenges thereto.
Three weeks later, the EPA issued notices announcing its withdrawal of the HWIR proposal and rescission of the sunset provision. 57 Fed.Reg. 49,280, 49,280, col. 1 (1992) (withdrawing HWIR proposal); 57 Fed.Reg. 49,278, 49,278, col. 1 (withdrawing the sunset provision). In both notices, the EPA announced its intent to promulgate revisions to the mixture and derived-from rules within 12 to 24 months. 57 Fed.Reg. at 49,278, col. 2; 57 Fed.Reg. at 49,280, col. 3.
We are also asked to review the EPA’s treatment of wastes consisting of a mixture of a “Bevill waste” and one or more hazardous wastes. Bevill wastes are derived from the extraction, beneficiation, and processing of ores and minerals and are exempted from Subtitle C regulation by virtue of the Bevill Amendment to RCRA, 42 U.S.C. § 6921(b)(3)(A)(ii) (1988).
See generally Horsehead Resource Dev. Co. v. Browner,
II. DISCUSSION
The EPA’s regulations are to be upheld so long as they are not “arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with law.” 5 U.S.C. § 706(2)(A) (1988). Therefore, if an agency has acted within its- authority and presents a rational basis for its actions, we must affirm.
See KCST-TV, Inc. v. FCC,
A. Challenge to the Subtitle C Mixture and Derived-from Rules
A “court is not empowered to decide moot questions or abstract propositions, or to declare, for the government of future cases, principles or rules of law which cannot affect the result as to the thing in issue in the case before it.”
California v. San Pablo & Tulare R.R. Co.,
Petitioners argue that we may disregard the Chafee Amendment because it speaks only to the agency, not to the courts. The relevant language of the statute reads:
EPA shall promulgate revisions to [the Subtitle C mixture and derived-from rules] as reissued on March 3, 1992, by October 1, 1994, but any revisions to such paragraphs shall not be promulgated or be *583 come effective prior to October 1, 1993. Notwithstanding [the “sunset provision”], as reissued on March 3,1992, [the mixture and derived-from rules] shall not be terminated or withdrawn until revisions are promulgated and become effective in accordance with the preceding sentence.
We believe that the Chafee Amendment does more than that. We read its language as binding us as well as the agency. . By precluding termination of the regulations, Congress expressed a firm intent that the two rules remain in effect until October 1, 1994, when they will be replaced by new rules that the EPA is to issue by that date. That purpose would be frustrated if courts remained free to vacate the interim final rule before the new rules came into effect, thereby creating the regulatory gap the Chafee Amendment was enacted to prevent.
Cf. Robertson v. Seattle Audubon Soc’y,
— U.S. -, -,
Because we are precluded from offering petitioners the relief they seek, their challenge to these rules is moot.
Nevada v. Watkins,
We turn, then, to the Bevill petitioners’ challenges.
B. Challenges to EPA Treatment , of Mixtures of Bevill and Hazardous Wastes
The EPA addressed the problems arising out of the Bevill Amendment in a final rule issued on September 1,1989. 54 Fed.Reg. at 36,592. It dealt with Bevill/characteristic waste mixtures by revising the definition of hazardous waste in section 261.3 of its regulations. As revised and subsequently reissued, the definition distinguishes between two kinds of Bevill/characteristic waste mixtures. The first deals with a . Bevill waste that is mixed with a waste that “exhibits any of the characteristics of hazardous waste.” Id. § 261.3(a)(2)(i). The resulting mixture will be subject to Subtitle C regulation
if it exhibits a characteristic that would not have been exhibited by the excluded [e.g., Bevill] waste alone if such mixture had not occurred or if it continues to exhibit any of the characteristics exhibited by the non-excluded wastes prior to mixture.
40 C.F.R: § 261.3(a)(2)(i). The second deals with a Bevill waste that is mixed with a listed waste that is listed “solely because it exhibits one or more of the characteristics of hazardous waste.” This mixture will be subject to Subtitle C regulation unless “the resultant mixture no longer exhibits any characteristic of hazardous waste ... for which the hazardous waste ... was listed.” Id. § 261.-3(a)(2)(iii). With regard to mixtures of Bevill and listed wastes, the EPA concluded .that it would stand by the position it had taken in its April 17, 1989, notice of proposed rule-making; namely, that they would be governed by the Subtitle C mixture rules. 54 Fed.Reg. at 36,623.
These provisions, which deal, respectively, with Bevil/characteristic waste and Be-vill/listed waste mixtures, together constitute the “Bevill mixture rule” that we vacated in
Solite,
In Solite, we vacated the Bevill mixture rule on the ground that it assumed the validity of the Subtitle C mixture rule, which we *584 had vacated in Shell Oil. In doing so, we stated that
[i]f the EPA desires to and successfully does repromulgate the Subtitle C rule, it will similarly be able to repromulgate the Bevill rule, and attempt to justify the latter by reference to the former. Alternatively, the Agency may wish to justify the Bevill rule on independent grounds.
Solite,
The [Solite ] court’s opinion did not explicitly address the status of EPA’s rule change regarding the application of the hazardous waste characteristics to mixtures of Bevill-exempt wastes. The court in Shell Oil vacated the “mixture rule” of 40 CFR § 261.3(a)(2)(iv), which addresses mixtures of listed wastes and other solid wastes. Thus, to the extent that the Solite court addressed mixtures involving listed and Bevill wastes, today’s actions will reinstate the affected rules. However, since the Shell Oil court did not address mixtures of characteristic and Bevill wastes, that part of the decision by the Solite court appears to be in error.
57 Fed.Reg. at 7,631 (emphasis added).
The Bevill petitioners contest what they describe as the “summary repromulgation” of the Bevill mixture rule on two procedural grounds: First, they assert that the rule was issued without the prior notice and opportunity for comment and without the reasoned explanation required by the Administrative Procedure Act (“APA”), 5 U.S.C. § 553(b) & (c); and second, they maintain that the EPA did not demonstrate that it had good cause to dispense with prior notice and comment, as required by 5 U.S.C. § 553(b)(3)(B). We consider this argument as it applies to éach provision of the Bevill mixture rule.
1. The Bevill/Characteristic Waste Provision
The Bevill petitioners acknowledge that the EPA had provided notice and secured comment before the initial issuance of the Bevill/characteristic waste provision in 1989. They assert, nevertheless, that intervening events required a fresh opportunity for comment. The EPA responds, in its brief, that it was not required to reopen notice and comment proceedings because the comments received in response to its April 17, 1989, notice of proposed rulemaking remain fresh and relevant enough to satisfy the requirements of the APA. The agency maintains, further, that because it had fully explained its reasons for promulgating this provision at the time of its original issuance, there was no need for it to reiterate them in the interim final rule.
We agree with petitioners that the EPA’s repromulgation of the Bevill/characteristic waste provision was proeedurally flawed. In
Action on Smoking and Health v. CAB,
This does not necessarily require the EPA to “start from scratch” and initiate new notice and comment proceedings.
Id.
at 800. The APA’s good cause exception may be invoked on a finding “that notice and public procedure thereon are ... unnecessary.” 5 U.S.C. § 553(b)(3)(B) (1988). If the original record is still fresh, a new round of notice and comment might be unnecessary. Such a finding, however, must be made by the agency and supported in the record; it is not self-evident. “Although the Administrative Procedure Act does not establish a ‘useful life’ for a notice and comment record, clearly the life of such a record is not infinite.”
ASH,
*585
2. Bevill/Listed Wastes Provision
The EPA maintains that the Bevill/listed wastes provision, which applies the Subtitle C mixture rule to mixtures of Bevill and listed wastes, is nothing more than an interpretation of that rule and is therefore exempt from the APA’s requirements. We agree that in construing the mixture rule to encompass such wastes, the EPA did not “create law”; rather, it made a “statement[ ] as to what [it] thinks the ... regulation means.”
Gibson Wine Co., Inc. v. Snyder,
III. Conclusion
We hold that petitioners’ challenges to the Subtitle C mixture and derived-from rules, including the EPA’s interpretation of the former to apply to mixtures of Bevill and listed wastes, are moot because the Chafee Amendment has enacted those rules as so interpreted into law. We vacate the provision of the Bevill mixture rule concerning Bevill/charae-teristic waste mixtures because the provision was reissued without compliance with the rulemaking requirements of the APA.
So ordered.