Full opinion text
PER CURIAM: CONTENTS Page I. Background. 477 II. Discussion. 482 A. Standard of Review. 482 B. High Volume Criteria. 483 1. Congressional Intent. 483 2. APA Compliance. 484 3. Methodological Objections. 485 (a) Consideration of Other Special Wastes. 485 (b) Overly Stringent High Volume Measurement. 486 C. Low Hazard Criterion. 488 D. The 50 Percent Rule. 490 E. Future Waste Streams. 491 F. Application of Section 3004(x) to Non-BeviU Wastes. 492 G. The Mixture Rule. 493 H. The Treatment Permit Requirement. 494 I. Du Pont’s Chloride-Ilmenite Process. 494 J. Chrome Tailings. 495 1. Background. 495 Page 2. Analysis. 496 K. Lead Process Wastewater. 497 1. Background. 497 2. Analysis. 498 L. Lightweight Aggregate Air Pollution Control Dust/Sludge. 498 1. Background. 498 2. Analysis. 499 III. Conclusion. 500 In Environmental Defense Fund v. EPA, 852 F.2d 1316 (D.C.Cir.1988), cert. denied, 489 U.S. 1011, 109 S.Ct. 1120, 103 L.Ed.2d 183 (1989) {“EDF II”), this court ordered the Environmental Protection Agency (“EPA”) to determine the ore and mineral processing wastes that qualify under the Bevill Amendment “mining waste exclusion,” 42 U.S.C. § 6921(b)(3)(A)(ii), for exemption, at least temporarily, from the hazardous waste management regime of Subtitle C of the Resource Conservation and Recovery Act (“RCRA”), 42 U.S.C. §§ 6921-6939b. This case is the follow up to that 1988 decision. Upon the EPA’s completion of the rulemaking we ordered in EDF II, members of the mineral and chemical processing industry, urging broader interpretation of the Bevill Amendment mining waste exemption from regulation, petitioned for our review. We uphold the EPA’s determinations in principal part. On two matters, however, we conclude that reconsideration by the Agency is necessary: (1) we vacate EPA’s determination that lightweight aggregate residuals do not meet the Agency’s high volume criterion, for the record shows that EPA decided that matter without providing due notice and opportunity to comment; (2) we remand for EPA to provide a more adequately reasoned explanation of its denial of the Bevill Amendment exclusion for the wastes from Du Pont’s chloride-ilmenite process. Finally, we remand without opinion two aspects of this rulemaking that EPA based upon the Subtitle C mixture rule, which we vacated recently in another case. I. Background Subtitle C of RCRA, enacted in 1976, requires EPA to develop a comprehensive regulatory scheme for the treatment, storage, and disposal of hazardous wastes. See 42 U.S.C. §§ 6921-6931. Section 8002 of RCRA, 42 U.S.C. § 6982, directs EPA to conduct special studies and research on certain categories of waste, including mining waste. See 42 U.S.C. § 6982(f) (requiring EPA to conduct “a detailed and comprehensive study” of adverse environmental effects of “solid wastes from active and abandoned surface and underground mines,” addressing adequacy of current means of disposal and utilization of such wastes). In its first proposal for regulations governing hazardous waste management under Subtitle C, EPA noted a category of “special waste,” for which “special standards” might be appropriate. 43 Fed. Reg. 58,946, 58,992 (1978). EPA’s “limited information” indicated that “such waste occurs in very large volumes, that the potential hazards posed by the waste are relatively low, and that the waste generally is not amenable [to the Subtitle C controls developed for industrial and manufacturing wastes].” Id. at 58,991-92. EPA identified, as one category of special waste, hazardous wastes “from the extraction, benefi-ciation, and processing of ores and minerals.” Id. at 59,016. In final regulations released in May 1980, EPA identified the characteristics of hazardous waste and listed as subject to Subtitle C regulation specific hazardous wastes. 45 Fed.Reg. 33,084 (1980). EPA concluded that the less inclusive definition of hazard and more relaxed regulatory requirements adopted in the final rule “accomplish[ed] the objective of, and eliminate[d] the need for, a special solid waste category.” Id. at 33,174. Consequently, EPA’s final regulatory scheme abandoned the concept of special waste, and would have subjected all wastes meeting EPA’s modified hazard criteria to Subtitle C regulation. Id. at 33,-175. A month before the Subtitle C regulations were to take effect, Congress altered EPA’s course by enacting the Bevill Amendment as part of the Solid Waste Disposal Act Amendments of 1980. In pertinent part, the Bevill Amendment directed EPA to study any adverse health and environmental effects “of solid waste from the extraction, beneficiation, and processing of ores and minerals,” and to submit a report to Congress by October 21, 1983. 42 U.S.C. § 6982(p). The Amendment further required EPA, within six months of reporting to Congress, and after public hearings and an opportunity for comment, either to “determine to promulgate regulations” governing the subject wastes, or to “determine that such regulations are unwarranted.” 42 U.S.C. § 6921(b)(3)(C). Pending pursuit and completion of the mining waste studies and, thereafter, until EPA’s final regulatory determination, the Bevill Amendment prohibited the Agency from regulating mining and mineral processing wastes as hazardous wastes within the compass of Subtitle C. 42 U.S.C. § 6921(b)(3)(A)(ii). In November 1980, EPA amended its hazardous waste regulations to incorporate the Bevill Amendment’s exemption of mining wastes from Subtitle C controls. 45 Fed.Reg. 76,618 (1980). The regulatory amendment tracked the statutory language, exempting from Subtitle C regulation “[sjolid waste from the extraction, be-neficiation and processing of ores and minerals.” Id. at 76,620; 42 U.S.C. § 6921(b)(3)(A)(ii). As “an immediate but temporary accommodation” of requests from the mining industry for “clear guidance” on the scope of the exemption, EPA announced an interpretation of the Bevill Amendment “to include solid waste from the exploration, mining, milling, smelting and refining of ores and minerals.” 45 Fed.Reg. at 76,618-19. The Agency questioned whether Congress intended so broad an exclusion from regulation, however, and announced that it would review the legislative history of the Bevill Amendment and consider public comments to determine definitively the proper scope of the exemption. Id. at 76,618-19. EPA did not meet the October 1983 statutory deadline to complete the Bevill study and report to Congress. Consequently, all mining wastes remained exempt from Subtitle C regulation. In September 1984, the Environmental Defense Fund and two citizens groups sued the Agency for failure to complete the studies and make the regulatory determinations as required by law. See Concerned Citizens of Adamstown v. EPA, No. 84-3041 (D.D.C. Aug. 21, 1985) (discussed in EDF I, 852 F.2d at 1311, and EDF II, 852 F.2d at 1321). EPA, in response to the litigation, indicated its intention “to reinterpret the mining waste exclusion to remove certain smelting and refining {i.e., processing] wastes ... from its scope.” See EDF II, 852 F.2d at 1321. The district court granted summary judgment for the Adamstown plaintiffs, and imposed on EPA a timetable for the Agency’s reinterpretation of the mineral processing waste category, completion of the required study, and rendition of the regulatory determination for processing wastes. See EDF II, 852 F.2d at 1321. In compliance with the court order in Adamstown, EPA proposed to limit its definition of ore and mineral processing wastes, for Bevill Amendment purposes, to those wastes meeting the “special waste” criteria first mentioned in EPA’s 1978 proposed Subtitle C regulations. 50 Fed.Reg. 40,292, 40,294 (1985). EPA later withdrew its proposed reinterpretation, however, because the proposal “did not set out practically-applicable criteria for distinguishing processing from non-processing wastes.” 51 Fed.Reg. 36,233, 36,235 (1986). In EDF II, this court, again on the petition of the Environmental Defense Fund, held that “EPA’s decision to withdraw its proposed [processing wastes] reinterpretation in its entirety was arbitrary and capricious and contrary to law because it ... reaffirmed an impermissibly over-broad interpretation of the Bevill Amendment.” EDF II, 852 F.2d at 1326. Reviewing EPA’s interpretation of the Bevill Amendment under the analytical framework of Chevron U.S.A. Inc. v. Natural Resources Defense Council, Inc., 467 U.S. 837, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984), the court first determined that “the statutory term ‘processing’ does not on its face admit of a standard definition, and ... the precise meaning of that term is not fully apparent from the structure of the statute.” EDF II, 852 F.2d at 1327. The court therefore turned to the legislative history of the Be-vill Amendment “for more precise guidance on Congressional intent.” Id. Upon reviewing the legislative history of the Bevill exclusion from regulation, the court found the guidance it sought. The EDF II panel concluded from the legislative history that “the key to understanding Congress’s intent is the concept of ‘special waste’ articulated in the regulations proposed by EPA on December 18, 1978 following the enactment of RCRA.” Id. (citing 43 Fed.Reg. 58,991-92 (1978); 50 Fed. Reg. 40,293-94 (1985)). From the remarks of Congressman Bevill and other legislators on the House floor when the Bevill Amendment was introduced, and the Conference Committee Report accompanying the 1980 amendments to RCRA, the court found it clear that Congress did not intend the mining waste exclusion to encompass all wastes from primary smelting and refining. On the contrary, Congress intended the term “processing” in the Bevill Amendment to include only those wastes from processing ores or minerals that meet the “special waste” criteria, that is, “high volume, low hazard” wastes. Id. at 1328-29. In granting relief, the court imposed on EPA a schedule “for fulfilling its statutory obligations with respect to processing wastes under the Bevill Amendment.” Id. at 1331. The court ordered EPA to propose, and, after notice and comment, determine “which processing wastes remain within the Bevill exclusion as ‘high volume, low hazard’ special wastes.” Id. As to the wastes so identified, the court further directed EPA to complete the study required by the Bevill Amendment, report to Congress, and make a regulatory determination, within six months of the submission of EPA’s report to Congress, with respect to those wastes. Id. Following EDFII, EPA issued three notices of proposed rulemaking (“NPRMs”), culminating in two final rules. In the first NPRM, published October 20, 1988 (“10/88 NPRM”), EPA proposed definitional criteria to identify mineral “processing” operations, and quantitative measures to identify “high volume” wastes. 53 Fed.Reg. 41,-288, 41,290-94 (1988). To develop a high volume criterion, EPA evaluated the annual generation rates of individual mineral processing waste streams in metric tons on both a plant-specific and an industry-wide basis. Id. at 41,292-94. The Agency quantified the high volume measure by examining the generation rates of mineral extraction and beneficiation wastes, oil and gas wastes, and wastes currently managed under Subtitle C. Id. at 41,293-94. The proposed volumetric threshold of 50,000 metric tons per year (“mt/yr”) per facility was calculated to retain within Bevill coverage mineral processing wastes generated in volumes comparable to the largest volume wastes managed at the top ten percent of Subtitle C facilities. Id. at 41,294. EPA declined at that stage to establish a “low hazard” standard. Id. at 41,294-95. Applying the proposed criteria, EPA identified 15 wastes meeting the “processing” definition and “high volume” measure, and solicited püblic comment on its proposed approach. Id. at 41,288, 41,296. In a second NPRM, published April 17, 1989 (“4/89 NPRM”), EPA revised the “special waste” criteria and modified the list of mineral processing wastes proposed for retention within the Bevill mining waste exclusion. 54 Fed.Reg. 15,316 (1989). The Agency proposed to establish separate high volume thresholds for “solid and acqueous liquid waste streams,” to account for large differences noted by EPA, i.e., Subtitle C facilities, the Agency observed, typically managed liquids in far larger volumes than solids. Id. at 15,331. EPA retained the 50,000 mt/yr standard for solid wastes and proposed a 1.5 million mt/yr standard for liquid wastes. Id. Further augmenting the initial notice, EPA’s 4/89 NPRM proposed a “low hazard” criterion to screen out from Bevill Amendment coverage mineral processing wastes that are “clearly not low hazard.” Id. at 15,331. The low hazard standard was intended to “remove from the [Bevill] exclusion wastes that may pose risk or hazard to such a great extent or magnitude that they cannot be considered ‘special wastes,’ irrespective of volume.” Id. at 15,322. EPA proposed to test all wastes meeting the “processing” definition and “high volume” criteria for corrosivity, using a pH test, and for toxicity and mobility, using a newly developed procedure called Method 1312. Id. at 15,339-40. Any high volume processing waste that failed either proposed test would be ineligible for Bevill Amendment exemption from Subtitle C regulation. Id. at 15,340. Because of limited data, EPA was then unable to apply the new hazard criteria to most high volume processing wastes. Id. The Agency planned to promulgate a final rule in September 1989 to establish the special waste criteria and take final action on six wastes proposed for Bevill coverage and three wastes proposed for elimination from that category. Id. at 15,317. The Agency conditionally retained an additional 33 wastes that satisfied the “processing” and “high volume” criteria, but for which EPA lacked sufficient data to test for hazard. Id. at 15,342. EPA planned to test those wastes and projected that in January 1990 it would finally determine their Bevill Amendment status. Id. In a final rule published in September 1989 (“9/89 Rule”), EPA settled on the “special waste” criteria for identifying Be-vill mineral processing wastes. 54 Fed. Reg. 36,592 (1989). As proposed in the 4/89 NPRM, EPA established separate high volume criteria for liquid and non-liquid wastes. Id. at 36,607. In quantifying the high volume cut-offs, EPA replaced as its source of data on Subtitle C facilities its 1985 National Biennial Report of Hazardous Waste Generators and Treatment, Storage, and Disposal Facilities Regulated Under RCRA (Draft) (“1985 Biennial Report”), used in both the 10/88 and 4/89 NPRMs, with its newly available National Survey of Hazardous Waste Treatment, Storage, Disposal, and Recycling Facilities (“TSDR Survey”). Id. at 36,608. The TSDR Survey, containing “detailed information about volumes and specific types of wastes generated and managed at Subtitle C facilities during calendar year 1986[,] ... allowed EPA to conduct a waste stream-level analysis of current management practices and hazardous waste volumes managed at facilities regulated under [S]ubtitle C of RCRA.” Id. Using this more recent and complete data, EPA examined individual waste-code data for waste streams entering Subtitle C landfills to develop a revised criterion for solid/sludge materials, and for waste streams entering wastewater treatment processes, surface impoundments, and injection wells to develop a cut-off value for liquid waste streams. The final criterion values reflect the largest single waste code managed at the 95th percentile of the Subtitle C facilities employing these hazardous waste management techniques. Id.; see also Development of the High Volume Criterion for Mineral Processing Wastes (Aug. 18, 1989), reproduced in Joint Appendix (“JA”) at 171-73. This methodology produced a final high volume criterion of 45,000 mt/yr per facility for non-liquid wastes and one million mt/yr per facility for liquid wastes. 54 Fed.Reg. at 36,594. The final low hazard screening prescription established a maximum level of mobility and toxicity for both liquid and non-liquid wastes, and a range of pH corrosivity, applicable only to liquid wastes, as the outer limits beyond which a waste was considered “clearly not low hazard” and thus ineligible for Subtitle C exclusion under the Bevill Amendment. Id. at 36,596, 36,630-31. The final toxicity/mobility standard, which employed EPA’s newly developed Method 1312, excluded from Bevill coverage any waste containing hazardous constituents at a level greater than 100 times the maximum contaminant level (“MCL”) in EPA’s primary drinking water standards. Id. at 36,630. The final corro-sivity test placed outside Bevill coverage any waste with a pH of less than one or greater than 13.5. Id. at 36,631. EPA applied these final “special waste” criteria to determine the Bevill status of 23 mineral processing wastes: five wastes were retained within the Bevill Amendment and 18 were ruled outside Bevill’s scope. Twenty wastes that appeared to satisfy the “processing” definition and high volume standard were conditionally retained within the Bevill exclusion, pending accumulation of further data necessary to apply the low hazard criterion. Id. at 36,631-32. In a third NPRM issued in mid-September 1989 (“9/89 NPRM”), EPA applied the final “special waste” criteria to the 20 mineral processing wastes conditionally retained for Bevill coverage in the 9/89 Rule, and proposed their final Bevill status. 54 Fed.Reg. 39,298 (1989). In a rule published in January 1990 (“1/90 Rule”), EPA made final the Bevill status of the 20 wastes, removing five from Bevill coverage and retaining the remaining 15. 55 Fed.Reg. 2322, 2342 (1990). Thus, EPA designated a total of 20 mineral processing wastes — five identified in the 9/89 Rule and 15 identified in the 1/90 Rule — for continued temporary exemption from Subtitle C regulation, pending the Agency’s detailed study, report to Congress, and ultimate regulatory determination under the Bevill Amendment. Id. Any wastes ruled outside Bevill’s scope would be subject to Subtitle C regulation if found to exhibit one or more of the hazardous characteristics identified by EPA in 1980 pursuant to RCRA. See 54 Fed.Reg. at 36,595. In these consolidated petitions for review, a number of mineral and chemical production companies, several associations representing mining and chemical industry interests, and the Mayor and City Council of Baltimore (collectively “petitioners”) challenge on numerous grounds EPA’s 9/89 and 1/90 Rules. Essentially, petitioners argue that EPA’s “special waste” criteria subvert congressional intent by excluding all but a few mineral processing wastes from the waste-specific study and regulatory determination required under the Be-vill Amendment. Petitioners charge that EPA has violated Congress’ statutory directive by paring down the scope of the Bevill study, thereby assigning RCRA regulatory status to allegedly Bevill wastes from mineral processing. See Joint Brief of Consolidated Petitioners and Intervenors (“Jt. Brief”) at 11 (summary of argument). In the main, we find that EPA’s rulemak-ing is consistent with this court’s decision in EDF II and reflects a permissible interpretation of the Bevill Amendment. We therefore affirm EPA’s determinations in principal part. II. Discussion A. Standard of Review In line with this court’s opinion in EDF II, EPA reviewed the administrative development of the “special waste” concept during the late 1970s. See 54 Fed.Reg. at 15,318-19. The Agency examined closely a key background document, completed in the fall of 1979, that (1) identified the criteria EPA used to develop the original list of “special wastes” in the 1978 proposed RCRA regulations, and (2) refined those criteria in response to comments on the 1978 proposal. Id.; see Draft Background Document, Introduction and Criteria for Special Waste (Nov. 2, 1979) (“Special Waste Background Document”), portions reproduced in JA at 200-07, JA Supp. at 593. EPA found it clear that, in 1978, the Agency had in view “several specific criteria (principally low hazard, high volume, and infeasibility of Subtitle C technical requirements) ... to evaluate potential special wastes”; moreover, the Agency then anticipated that “the group of wastes [eligible for] the temporary exemption from full Subtitle C regulation [would] be both finite and relatively small.” 54 Fed.Reg. at 15,-319. Reiterating that “high volume and low hazard” are “the key elements in identifying special wastes,” EPA recalled the function these factors play in determining which wastes are appropriate for temporary, and possibly permanent, exclusion from Subtitle C regulation under the Bevill Amendment: High volume is the principal indicator of whether a particular waste is amenable to management under Subtitle C of RCRA. A consideration of hazard is necessary to identify and remove from the exclusion wastes that may pose risk or hazard to such a great extent or magnitude that they cannot be considered “special wastes,” irrespective of volume. Id. at 15,322. EPA observed, however, that neither the legislative history of the Bevill Amendment, nor the regulatory background of the “special waste” concept, precisely defines the terms “high volume” or “low hazard.” See id.; see also 54 Fed.Reg. at 36,595. Nor do these terms “convey a self-evident, accepted meaning.” See EDF II, 852 F.2d at 1316. Because Congress has not “directly addressed the precise question at issue,” that is, the appropriate delineation of the “special waste” concept, and the attendant “high volume” and “low hazard” criteria, the question on review is “whether the agency’s answer is based on a permissible construction of the statute.” Chevron, 467 U.S. at 843, 104 S.Ct. at 2782. In EDF II, we held that “Congress intended the Bevill exclusion to encapsulate the ‘special waste’ concept articulated by the EPA in 1978,” 852 F.2d at 1329, and we review EPA’s rules, with the deference mandated by Chevron, for conformity to the statute so understood. B. High Volume Criteria EPA understood that Congress intended the Bevill exclusion to encompass “only those waste streams that are generated in such quantities as to be potentially unmanageable under [SJubtitle C regulations.” 54 Fed.Reg. at 36,611. Consistent with Agency documents prepared in conjunction with EPA’s 1978 proposal on special wastes, the Agency viewed volume as “the most relevant and objective measure” of the technical feasibility of subjecting waste to Subtitle C controls. See 54 Fed. Reg. at 15,326; see also id. at 15,318 (quoting Special Waste Background Document (“apparent technological difficulty in applying [proposed Subtitle C] regulations to the waste because of volumes involved at typical facilities” was a “driving force” in developing the original list of “special wastes”)). EPA logically concluded that “comparison of mineral processing waste volumes with those of wastes managed under Subtitle C controls” was the most “appropriate analytical basis for developing the high volume criterion.” 54 Fed.Reg. at 36,611. The Agency consequently devised a methodology to calculate “volumetric cutoffs ... reflecting] some of the largest quantities of individual and identifiable waste streams managed at facilities that are currently in the Subtitle C regulatory system.” Id. at 36,629. EPA examined the generation rates of Subtitle C wastes managed at facilities disposing of solid/sludge materials in landfills, or employing wastewater treatment processes, surface impoundments, and injection wells to manage hazardous liquid wastes — disposal techniques that would be used to manage mineral processing wastes under Subtitle C. Id. at 36,608, 36,629. The Agency identified the largest individual waste stream managed by such techniques at each facility, and “computed univariate statistics on the resulting distribution.” Id. at 36,629. The final high volume criteria — 45,000 mt/yr per facility for solids, one million mt/yr per facility for liquids — represent “the largest individual waste stream managed by the facility at the 95th percentile of the relevant distribution.” Id. Beyond question, a high volume standard for Bevill mineral processing wastes is in order. Petitioners do not argue otherwise; rather, they challenge the particular high volume criteria established by EPA on three grounds. First, petitioners charge that the selected criteria frustrate the congressional intent underlying the Bevill Amendment. Next, they complain that, in violation of the Administrative Procedure Act (“APA”), 5 U.S.C. § 553, EPA failed to provide adequate notice and opportunity to comment on the data and methodology used in developing the high volume standards. Finally, petitioners assert that EPA’s method of calculating the quantitative volumetric thresholds was improperly biased toward overly stringent standards and was therefore arbitrary and capricious. We conclude that EPA’s high volume criteria are consistent with a permissible interpretation of the Bevill Amendment, were developed in accord with the APA, and reflect methodological choices properly within the Agency’s discretion. 1. Congressional Intent Petitioners argue that EPA’s “unreasonably high volumetric thresholds ... transformed what was intended by Congress to be a screening analysis into a final method for determining the regulatory status of mineral processing wastes.” Jt. Brief at 31. Petitioners challenge EPA’s “false equation of ‘high volume’ and ‘non-amenability’ ” as without “basis in the language or legislative history of the Bevill Amendment.” Jt. Reply at 5-6 & n. 8. Congress intended EPA to determine the amenability of mineral processing wastes to Subtitle C regulation through the multi-factored analysis required by the Bevill Amendment, petitioners assert, not through the application of a rigid high volume screening criterion. Id. at 7-8. For a waste within its scope, the Bevill Amendment no doubt requires an in-depth, multi-factored, context-specific study and regulatory determination. See 42 U.S.C. §§ 6921(b)(3), 6982(p). This court found it equally clear, however, that Congress did not intend to sweep all mineral processing wastes within Bevill Amendment coverage, but only those that satisfied threshold high volume, low hazard criteria to be determined by EPA. See EDF II, 852 F.2d at 1329. We discern no departure from Congress’ instruction, or abuse of discretion, in EPA’s use of precise quantitative measures to make the threshold classifications, while reserving for wastes thus classed “Bevill” the closer study antecedent to determining the regime for their regulation. Petitioners apparently would have the Agency make a multi-factored analysis twice over. We see no legislative command for the scheme petitioners ask us to order. 2. APA Compliance Petitioners accuse EPA of having “performed a classic ‘bait-and-switch’ ” by “substituting at the last moment one set of data and analysis for another” when the Agency replaced the 1985 Biennial Report with the TSDR Survey as the source of data on which the final quantitative volumetric measures were based. Jt. Brief at 13. In petitioners’ view, EPA thus deprived the public of the notice and opportunity to comment guaranteed by the APA. See 5 U.S.C. § 553. We conclude that the EPA’s high volume criteria do not fail on notice and comment grounds. The APA requires that a notice of proposed rulemaking include “either the terms or substance of the proposed rule or a description of the subjects and issues involved,” 5 U.S.C. § 553(b), and that the agency “give interested persons an opportunity to participate in the rulemaking through submission of written data, views, or arguments.” 5 U.S.C. § 553(c); see Air Transport Ass’n v. CAB, 732 F.2d 219, 224 (D.C.Cir.1984). Integral to the notice requirement is the agency’s duty “to identify and make available technical studies and data that it has employed in reaching the decisions to propose particular rules.... An agency commits serious procedural error when it fails to reveal portions of the technical basis for a proposed rule in time to allow for meaningful commentary.” Connecticut Light and Power Co. v. NRC, 673 F.2d 525, 530-31 (D.C.Cir.), cert. denied, 459 U.S. 835, 103 S.Ct. 79, 74 L.Ed.2d 76 (1982). At the same time, consistent with the APA, an agency may use “supplementary” data, unavailable during the notice and comment period, that “expand[s] on and confirm[s]” information contained in the proposed rulemaking and addresses “alleged deficiencies” in the pre-existing data, so long as no prejudice is shown. Community Nutrition Institute v. Block, 749 F.2d 50, 57-58 (D.C.Cir.1984); see also Air Transport Ass’n, 732 F.2d at 224 (APA requirements met despite agency’s reliance on internal staff studies unavailable to public before rule’s adoption, because “critical elements” of proposal did not change and “final rule was a ‘logical outgrowth’ of the proposed rule”) (quoting Small Refiner Lead Phase-Down Task Force v. EPA, 705 F.2d 506, 547 (D.C.Cir.1983)). Petitioners do not point to inaccuracies in the data contained in the TSDR Survey. See Community Nutrition Institute, 749 F.2d at 58 (no prejudice from agency’s response to comments in form of “new scientific studies” where petitioners did “not even suggest that the new studies were defective”). Nor does the record suggest that EPA hid or disguised the information it used, or otherwise conducted the rulemaking in bad faith. Cf Connecticut Light and Power Co., 673 F.2d at 531 (“To allow an agency to play hunt the peanut with technical information, hiding or disguising the information that it employs, is to condone a practice in which the agency treats what should be a genuine interchange as mere bureaucratic sport.”). Rather, petitioners’ complaint is with the way EPA used the data to calculate volumetric thresholds for Bevill status qualification of solid and liquid processing wastes. EPA’s methodology in selecting the high volume criteria, however, did not change significantly from the proposed notices to the final rule, and petitioners had ample opportunity to criticize EPA’s approach. In fact, the updated and expanded data in the TSDR Survey enabled EPA to respond to several industry objections to use of the data in the 1985 Biennial Report; by providing a more precise quantitative measure based on more complete information, the TSDR Survey confirmed the prior estimate of the upper bounds of waste volumes currently managed under Subtitle C controls. See Community Nutrition Institute, 749 F.2d at 58 (“It is impossible to perceive why correction of an asserted deficiency in earlier studies— which correction confirms the accuracy of those studies — should give rise to an additional opportunity to comment.”); cf. American Iron & Steel Inst. v. OSHA, 939 F.2d 975, 1009-1010 (D.C.Cir.1991) (OSHA violated APA by basing finding of economic feasibility on post-comment data apparently less reliable than, and inconsistent with, “all other important evidence in the record”). In sum, because EPA’s methodology remained constant, and because the added data was used to check or confirm prior assessments, we hold that the Agency did not violate the notice and comment provisions of the APA by using the TSDR data. 3. Methodological Objections This court’s review of EPA’s methodology in developing the high volume criteria is governed by the APA’s “arbitrary or capricious,” “abuse of discretion” standard. 5 U.S.C. § 706(2)(A). Under this familiar standard, we inquire “ ‘whether the [Agency’s] decision was based on a consideration of the relevant factors and whether there has been a clear error of judgment.’ ” Motor Vehicle Mfrs. Ass’n v. State Farm Mut. Automobile Ins. Co., 463 U.S. 29, 43, 103 S.Ct. 2856, 2866, 77 L.Ed.2d 443 (1983) (citation omitted). The record need only demonstrate that the Agency met its obligation to “examine the relevant data and articulate a satisfactory explanation for its action.” Id. (a) Consideration of Other Special Wastes Petitioners complain that in developing the high volume criteria for mineral processing wastes, EPA neglected to evaluate the volumes of wastes clearly within the Bevill Amendment’s scope and thereby ignored “the only direct evidence of Congressional intent relating to the special waste concept.” Jt. Brief at 16. EPA did indeed base its high volume criteria principally on a comparison of volume data from regulated Subtitle C facilities, but the Agency did not ignore the volumes of wastes within Bevill’s compass. The rulemaking record documents the consideration given to the generation rates of such wastes. See 53 Fed.Reg. at 41,293-94; 54 Fed.Reg. at 15,-330; Internal EPA Memorandum dated Oct. 19, 1988 re: Quantitative Basis for High Volume Mineral Processing Waste Criteria, reproduced in JA at 241-48. Quantitative comparisons showed that mineral processing wastes proposed for continued Bevill status in the 10/88 NPRM are generated in quantities that are comparable to many of the other special wastes, and that the lower bounds of the quantitative criteria approximate the lower limit of the quantities of waste generated by the other industry types contained within the Bevill exclusion. EPA Mem., Oct. 19, 1988 at 1, JA at 241. True, EPA rejected the suggestion to “use the lowest of extraction and beneficiation waste generation rates to establish the high volume threshold.” 54 Fed.Reg. at 36,611-12; see also 54 Fed.Reg. 15,330. As EPA reasoned, “Congress intended the Bevill exclusion to cover only those waste streams that are generated in such quantities as to be potentially unmanageable under [S]ubtitle C regulations”; therefore, the volumes of wastes currently managed under Subtitle C controls formed the “appropriate analytical basis for developing the high volume criterion.” 54 Fed.Reg. at 36,611; see also 54 Fed.Reg. 15,329. In EPA’s view, comparisons with Subtitle C wastes are not only reasonable and appropriate, but necessary. Comparisons with other Be-vill wastes, on the other hand, do not provide conclusive evidence but do suggest boundaries on what might be considered a high volume special waste. Id. at 15,329; see also id. at 15,330; 54 Fed.Reg. at 36,611. Nothing in the legislative history of the Bevill Amendment indicates that Congress contemplated a specific volumetric threshold, or intended the generation rate of any particular Bevill waste to serve as the cutoff for mineral processing wastes to qualify for exemption from Subtitle C regulation. Rather, the legislative record, as the EDF II panel concluded, demonstrates only that “Congress intended the Bevill exclusion to encapsulate the ‘special waste’ concept articulated by the EPA in 1978.” EDF II, 852 F.2d at 1329. Given the absence of more precise instructions from Congress, the EDF II court properly left to EPA the task of setting criteria for determining which mineral processing wastes are special wastes. Id. at 1331. EPA, we are satisfied, provided a reasonable explanation for its decision to base the high volume criteria on the volumes of waste generated and managed at Subtitle C-regulated facilities, and to use generation rates of other Bevill wastes as a “reality check” on the volume thresholds selected. See 54 Fed.Reg. at 15,330; 54 Fed.Reg. at 36,611. (b) Overly Stringent High Volume Measurement Petitioners charge that EPA’s data selection from the TSDR Survey and methodological choices “piled one conservative assumption atop another, resulting in high volume criteria that are so unreasonably high as to be arbitrary and capricious.” Jt. Brief at 18-19. Specifically, petitioners argue that by examining only facilities that use land disposal to manage solid wastes or treat hazardous wastewaters, ignoring small volume waste generators, and inelud-ing commercial waste management facilities, EPA improperly narrowed the comparative data base to exclude the majority of Subtitle C wastes. Id. at 19-22. Petitioners also contest EPA's decisions to consider only the largest waste stream managed at each facility in its data base, id. at 23, to use data that aggregated the volumes of individual Subtitle C waste streams, id. at 24-26, to establish separate high volume thresholds for liquid and solid wastes, id. at 27-28, and to select the 95th percentile as the statistical cutoff to define the numerical high volume standards. Id. at 28-30. EPA, we conclude, reasonably interpreted the “special waste” concept when the Agency decided to quantify the “high volume” criterion through an analysis of the technical feasibility of Subtitle C controls. EPA adequately explained, as logically within this permissible interpretation, each of the methodological decisions petitioners challenge. To the extent petitioners quarrel with EPA’s methodology or selection of a precise numerical measure, they have failed to demonstrate that the Agency acted in an arbitrary and capricious manner. See State Farm, 463 U.S. at 43, 103 S.Ct. at 2866. Petitioners fault EPA for not basing its high volume criteria on “the full universe of industrial Subtitle C facilities.” Jt. Brief at 19. But EPA reasonably limited the comparative data base to facilities using those Subtitle C management techniques that would most likely be employed to manage hazardous mineral processing wastes — landfills for solid wastes, and wastewater treatment processes, surface impoundments, and injection wells for liquid wastes. 54 Fed.Reg. at 36,608, 36,629. Small quantity waste generators, and those that do not employ these waste management techniques, could supply no data relevant to EPA’s inquiry into the technical feasibility of managing large volumes of mineral processing waste under Subtitle C. EPA similarly rejected the suggestion that “a relevant comparative analysis should reflect ‘typical’ quantities of hazardous waste generated.” 54 Fed.Reg. at 15,-329. Instead, endeavoring to identify mineral processing wastes generated in volumes so high as to resist Subtitle C controls, EPA appropriately concentrated its examination on the largest volume wastes currently managed under Subtitle C. Id. at 15,329; 54 Fed.Reg. at 36,611. The Agency likewise reasonably decided to include data from commercial Subtitle C waste management facilities in its analysis. EPA reasoned that information on waste volumes managed by commercial facilities was relevant to the Agency’s determination of “technical feasibility^] ... the fundamental issue addressed by the volume criterion.” 54 Fed.Reg. at 36,612. “[Cjonsider-ations of differential economic incentives facing operators of commercial and private hazardous waste management facilities,” EPA said, “are not relevant in resolving this [technical feasibility] issue.” Id. at 36,630. EPA’s decision to establish separate high volume thresholds for liquid and solid mineral processing wastes is similarly rooted in the Agency’s legitimate focus on technical feasibility. EPA proposed setting separate volumetric standards in the 4/89 NPRM, noting that Subtitle C facilities typically manage liquid wastes in far larger volumes than solid wastes. 54 Fed.Reg. at 15,331. The Agency finalized this approach in the 9/89 Rule. EPA thus properly recognized the “highly significant differences” in treatment processes and management options that rendered management of large volumes of wastewater “more technically feasible” than management of large volumes of solids. 54 Fed.Reg. at 36,630. EPA acknowledged the analytical inconsistency of using data on the generation rates of aggregated Subtitle C waste streams to calculate a waste stream-specific high volume threshold for mineral processing wastes. 53 Fed.Reg. at 41,293-94; 54 Fed.Reg. at 15,329; 54 Fed.Reg. at 36,-609-10. The TSDR Survey data, however, enabled EPA substantially to disaggregate the data on Subtitle C waste generation rates. Id. at 36,610; see also Development of the High Volume Criterion for Mineral Processing Wastes (Aug. 8, 1989) at 1-2, JA at 171-72 (describing methodology for developing high volume criterion based on TSDR Survey data, including formula for calculating disaggregated waste generation rates). Finally, EPA properly exercised its discretion in selecting the 95th percentile as the statistical cutoff to define the numerical high volume standards, permitting a 5% overlap between the volumes of Bevill mineral processing wastes and the volumes of wastes currently managed under Subtitle C. See 54 Fed.Reg. at 36,629. Environmental watchdog groups recommended a cutoff at the 99th percentile, allowing for an overlap of only one percent, while members of the mineral processing industry favored an overlap of “at least 10 percent,” translating to a cutoff at the 90th percentile. Id.; see Comments of National Audubon Society, et al. (May 31, 1989) at 55; Comments of American Mining Congress (May 31,1989) at 44. EPA explained in the 9/89 Rule that the percentile overlap was reduced from 10%, as proposed in the 10/88 and 4/89 NPRMs, to 5% because “problems with the data used in the analysis” (i.e., the 1985 Biennial Report), which had justified a lower percentile cutoff, had been resolved when “better data” (i.e., the TSDR Survey ) became available. 54 Fed.Reg. at 36,-613. EPA determined that this “much stronger” data supported a 5% overlap. Id. Given EPA’s logical conclusion that current management of large volume hazardous wastes indicates that Subtitle C regulation of that quantity of waste is technically feasible, the Agency reasonably selected a percentile cutoff that eliminated from Be-vill Amendment coverage those mineral processing wastes generated in volumes lower than the largest volume Subtitle C-managed wastes. In selecting a 95th percentile cutoff, resulting in a 5% overlap between the generation rates of large volume Subtitle C wastes and Bevill mineral processing wastes, EPA chose “a numerical standard ... within a ‘zone of reasonableness’ ” that warrants judicial approbation. See Small Refiner Lead Phase-Down Task Force v. EPA, 705 F.2d 506, 525 (D.C.Cir.1983) (citations omitted). C. Low Hazard Criterion To qualify as a “special waste” covered by the Bevill Amendment, a mineral processing waste, EPA has ruled, must not only be high volume, it must also be low hazard. Petitioners challenge the very inclusion of any low hazard criterion. They also challenge the particular hazard screening tests EPA used. We find EPA’s low hazard criterion and tests compatible with the legislative design, consistent with our decisions in EDF I and EDF II, and reasonably explained. We therefore reject petitioners’ challenges. According to petitioners, the “special waste” concept, as originally presented in EPA’s 1978 proposal, classified wastes as “special” because of their large volume and, consequently, the anticipated infeasibility of Subtitle C regulation. Jt. Brief at 33. While acknowledging EPA’s statement in the 1978 proposal that “hazardous ‘special wastes’ posed a ‘relatively low’ risk to human health and the environment,” id., petitioners insist that “volume, not hazard, is the key to the special waste concept.” Id. at 34 & n. 39. Volume, no doubt, is a necessary key, but EPA maintains it does not suffice to open the special processing waste category. Interpretation of the Bevill Amendment to exclude “wastes that are clearly not low hazard,” 54 Fed.Reg. at 15,331, we continue to hold, is consistent with congressional intent and the regulatory history of the special waste concept. See EDF II, 852 F.2d at 1329 (“Congress intended the term ‘processing’ in the Bevill Amendment to include only ... ‘high volume, low hazard’ wastes.”). The Agency’s 1978 proposal lists low hazard as one of the three identifying characteristics of special waste, along with large volume and lack of amenability to Subtitle C controls. 43 Fed.Reg. at 58,992. In its November 1979 Special Waste Background Document, EPA explained that it had deferred regulation of special wastes, pending further study, in part because “[t]he various special wastes pose only a low potential hazard to human health and the environment.” Special Waste Background Document at 21, JA at 205. The Agency, at that time, expressly established “low potential hazard ... as a criterion for special waste status,” and observed that, consequently, “all the [special] waste streams will pose no more than a minimal threat to human health and the environment during the several year interim period” in which EPA planned to study the wastes to determine appropriate regulatory action. Id. at 21-22, JA at 205-06; see also 54 Fed.Reg. at 15,318-19 (recounting that Background Document identifies “low potential hazard” as a key criterion EPA would use to evaluate petitions to designate special wastes). Petitioners further maintain that EPA’s imposition of a low hazard screening criterion conflicts with this court’s interpretation of the Bevill Amendment in EDF I. Jt. Brief at 34-35. In EDF I, the court upheld EPA’s regulatory determination under the Bevill Amendment to exempt hazardous mineral extraction and beneficiation wastes from Subtitle C controls, and to subject them instead to the less restrictive standards of RCRA Subtitle D. See EDF I, 852 F.2d at 1310. The court rejected the Environmental Defense Fund’s argument that EPA was required to regulate under Subtitle C any wastes found in the Bevill study to be “hazardous” under RCRA. “EPA’s interpretation of the Bevill Amendment as allowing the agency discretion to base its regulatory determination on a variety of factors,” the EDF I court held, “is a permissible construction of the statute.” Id. at 1313. Petitioners argue that by applying a low hazard screening criterion, EPA has made hazard the determinative factor in establishing the regulatory status of high volume processing wastes that would otherwise qualify for Bevill coverage, contrary to EDF I. It is not inconsistent, however, to interpret the Bevill Amendment as requiring a “context-specific” determination of hazard as one of several factors to be considered in regulating wastes definitively placed within Bevill’s scope, e.g., wastes from the extraction and beneficiation stages of mining, EDF I, 852 F.2d at 1315-16, and, at the same time, to construe the Amendment’s terms to exclude from Be-vill’s scope processing wastes that do not qualify as “low hazard.” EDF II, 852 F.2d at 1329. This is indeed the very interpretation our circuit approved in EDF I and EDF II, companion cases decided the same day. EPA adopted in the rulemaking on review low hazard tests generally less stringent than the RCRA hazardous waste characteristic tests normally used for Subtitle C wastes. Thus a waste qualifying as “low hazard” under Bevill might subsequently be found to contain a RCRA hazardous characteristic. See 54 Fed.Reg. at 36,597. Consistent with EDF I, EPA assured that the low hazard criterion is solely a preliminary screening device to determine which mineral processing wastes are special wastes, and will not be used in determining which wastes will subsequently be regulated under Subtitle C, either as a result of today’s rule or in the upcoming regulatory determination. Id. In sum, EDF I held only that EPA is not required to regulate high volume special wastes under Subtitle C simply because they exhibit a RCRA hazardous characteristic. That holding does not mean EPA is prohibited from using hazard as a criterion, along with volume, to determine which processing wastes fit the “special waste” category. Petitioners’ argument both overreads EDF I and is at odds with EDF II, which constantly juxtaposes “high volume, low hazard” in the context at hand. See EDF II, 852 F.2d at 1322, 1325, 1326, 1329, 1331. Petitioners further object to the tests EPA selected. The Agency selected Method 1312 as the procedure for extracting waste constituents from solid mineral processing wastes to test for toxicity and mobility. 54 Fed.Reg. at 36,597. EPA considered Method 1312, a recently developed leaching procedure, to be “generally less aggressive” than Method 1310, the leaching procedure used to measure the hazardous toxicity characteristic under RCRA. 54 Fed.Reg. at 36,597, 36,601. Petitioners argue that EPA “failed to verify the accuracy and precision of Method 1312” in measuring “hazards that may be posed by mineral processing wastes,” and that selection of the procedure was therefore arbitrary and capricious. Jt. Brief at 38. While EPA “ha[d] not yet completed its evaluation of Method 1312” when the procedure was first proposed in the 4/89 NPRM, the Agency reported that “work conducted to date indicates that the procedure is of acceptable precision.” 54 Fed. Reg. at 15,340. Because EPA’s evaluation of Method 1312 was incomplete, the Agency tested several mineral processing wastes using the “more aggressive extraction medium” of Method 1310, and neutral water testing, considered “only slightly less aggressive than the Method 1312 leaching medium.” Id. After retesting these wastes using Method 1312, EPA determined in the 9/89 Rule that “the new sampling and analytical data obtained using Method 1312 confirm the Agency’s earlier findings” from Method 1310 and neutral water testing. 54 Fed.Reg. at 36,601. This court does not “demand certainty where there is none,” Small Ref. Lead Phase-Down Task Force, 705 F.2d at 525, and the Agency here may apply its “ ‘expertise to draw conclusions from ... probative preliminary data not yet certifiable as “fact,” and the like.’ ” AMC v. EPA, 907 F.2d 1179, 1187 (D.C.Cir.1990) (quoting Ethyl Corp. v. EPA, 541 F.2d 1, 28 (D.C.Cir.) (en banc), cert. denied, 426 U.S. 941, 96 S.Ct. 2662, 49 L.Ed.2d 394 (1976)). Given the respect properly accorded EPA’s judgment in this area, use of Method 1312 as a testing mechanism, we rule, withstands petitioners’ attack. Petitioners also challenge EPA’s pH cor-rosivity test as arbitrary and capricious because “the pH standard overstates the potential hazard” of wastes containing “un-buffered” acids. Jt. Brief at 40. Petitioners state that a small amount of “unbuf-fered” acid in a waste will result in a very low pH, “even though the waste’s acidic content or potential hazard ... may be quite minimal.” Id. As EPA explained, however, “the fact that mineral acids are not appreciably buffered does not alter the fact that wastes of such low pH may pose a hazard” prior to treatment. 54 Fed.Reg. at 36,600. Petitioners have not demonstrated that EPA’s refusal to except unbuf-fered acids from the corrosivity test is arbitrary or capricious. EPA selected a pH range of 1.0 to 13.5 “to identify which wastes clearly are so corrosive that they do not merit continued regulatory exclusion and further study.” Id. The final low hazard corrosivity standard represents a relaxation by one order of magnitude of the RCRA hazardous characteristic pH standard of 2 to 12.5. Id. EPA determined that “any further increase in the pH range may result in wastes that are clearly not low hazard remaining in the Bevill exclusion, which may in turn compromise the protection of human health and the environment.” Id. Because the agency “examined the relevant data and ... articulated a rational explanation for its action,” EPA’s predictive low hazard screening criterion warrants our respect on review. Eagle-Picher Industries v. EPA, 759 F.2d 905, 921 (D.C.Cir.1985). D. The 50 Percent Rule The 9/89 Rule interprets the Bevill Amendment as applying only to wastes from mineral processing operations with feedstocks containing less than 50 percent scrap materials, see 54 Fed.Reg. at 36,629; for this purpose, in-process materials, which are derived from prior mineral processing operations, are counted as scrap regardless of their mineral content. See id. at 36,619-20. The Amendment itself does not define the terms “ores [or] minerals.” Because the statute is “silent” on this issue, our role is merely to determine whether EPA has permissibly construed the statute. See Chevron, 467 U.S. at 843, 104 S.Ct. at 2781. Petitioners assert that the 50 percent rule is not a permissible construction of the Bevill Amendment because it runs afoul of an underlying environmental objective of RCRA, namely “to conserve valuable material and energy resources by ... encouraging process substitution, materials recovery, properly conducted recycling and reuse, and treatment.” 42 U.S.C. § 6902(a), (a)(6). They point out that the limitation on in-process materials acts as a disincentive to the reuse of processed materials and thus promotes the extraction of additional virgin ores and minerals. According to EPA, the 50 percent rule strikes a balance between, on the one hand, promoting the reuse of scrap and in-process materials and, on the other, restricting the Bevill exclusion to primary processors. See 54 Fed.Reg. at 36,620. While a rule making the Bevill exclusion unavailable to some in-process materials may to that extent discourage recycling, it is necessary, in the Agency’s view, to “maintain[] the essential upper bound on the amount of non-ore present in a feedstock in order to ensure that wastes from operations that primarily process materials other than ores and minerals are not provided with an exclusion that Congress did not intend.” Id. We take the Agency’s point. EPA must distinguish somehow between primary mineral processing operations, which qualify as Bevill mineral processing, and secondary processing operations, which do not. The 50 percent rule supplies a reasonable line of demarcation, classifying every operation on the basis of whether it is primarily of the one or of the other sort. Petitioners also argue that the 50 percent rule purports to regulate the production process, which the Agency acknowledges would exceed its authority. As we have just established, however, Congress delegated to EPA the authority — indeed the obligation — to determine which processes qualify for the Bevill mineral processing exclusion, and it is reasonable for the Agency to exclude from the Bevill category operations that use predominantly scrap and in-process materials. That decision may have an effect upon the economics of the production process, but it is not for that reason alone a regulation of the production process itself. Thus, we uphold the 50 percent rule against the two challenges pressed by petitioners. E. Future Waste Streams The 9/89 Rule denies Bevill status to any waste stream that did not exist when the Rule was promulgated, and to any extent waste stream that did not meet the Bevill criteria at the time of rulemaking. According to the Agency, it could and did make a one-time determination of Bevill status. Wastes not yet in existence and wastes not meeting the high volume/low hazard criteria during any of the past five years would ... not be eligible for Bevill exclusion status in the future. 54 Fed.Reg. at 36,595. As a result, an after-arising waste stream that meets all of the substantive criteria for Bevill status will be regulated under either Subtitle C or Subtitle D of RCRA. Id. at 36,596. Petitioners argue that denying Bevill status to future waste streams is contrary to the purpose of the Bevill Amendment. They point in particular to special wastes that do not currently satisfy the high volume threshold but will do so in the future. The statutory provision directing EPA to study Bevill wastes suggests by its terms that a one-time study is sufficient. See 42 U.S.C. § 6982(p) (“The Administrator shall conduct a detailed and comprehensive study ... [and] shall publish a report of such study_”). The way in which the temporary nature of the Bevill Amendment is expressed in the statute also lends support to EPA’s interpretation. See 42 U.S.C. § 6921(b)(3)(A) (Bevill exclusion operative “until at least six months after ... submission of the applicable study”). In any event, this court’s holding in EDF II secures EPA’s position that a one-time determination is sufficient. There we interpreted the Bevill Amendment as an exclusion specifically for “the category of wastes designated as ‘special wastesf ]’ ... in EPA’s 1978 proposed hazardous waste regulations.” EDF II, 852 F.2d at 1329 (quoting 51 Fed.Reg. 36,234 (1986)). While we did not go so far as to foreclose Bevill status for a future waste that might satisfy a pre-set criterion, we clearly enough rejected the theory that Congress intended the coverage of the Bevill exclusion to evolve with time. In sum, while the Bevill Amendment itself is silent on the coverage of future waste streams, the statutory framework of RCRA and the precedent of EDF II both support EPA’s position. In these circumstances, EPA’s position is surely reasonable, and we must uphold it. F. Application of Section 300^(x) to Non-Bevill Wastes In 1984 Congress added to RCRA the Hazardous and Solid Waste Amendments, commonly known as the “Simpson Amendment,” codified at section 3004(x). This section authorizes EPA to relax Subtitle C regulations for “the extraction, beneficiation or processing of ores and minerals” — a list of operations virtually identical to that in the Bevill Amendment. Accordingly, in the course of implementing the Bevill Amendment, EPA addressed the question whether a waste that is denied Bevill status is nonetheless eligible for relaxed regulation pursuant to section 3004(x). In the preamble to its 9/89 Rule, EPA read section 3004(x) as having the same scope as the Bevill Amendment: “the Simpson Amendment would not apply to wastes that are not special wastes and that would therefore be removed from the Be-vill exclusion by the proposed rule.... [T]he proper reading of section 3004(x) is that it applies only to special wastes as defined by today’s final rule.” 54 Fed.Reg. at 36,624-25. In this EPA merely assigned the same meaning to the same statutory formula in the two places where Congress used it. That seems eminently reasonable, in the absence of a particular reason to do otherwise. Compare Alabama Power Co. v. Costle, 636 F.2d 323, 396 (D.C.Cir.1979) (“Given no expression of any contrary intent in the Act or in the legislative history regarding these definitions, we must assume that the meaning of a particular term is to be consistent throughout the Act.”) with National Ass’n of Casualty and Surety Agents v. Board of Governors of the Fed. Reserve Sys., 856 F.2d 282, 287 (D.C.Cir.1988) (upholding agency’s different interpretations of similar statutory phrases based upon “their different economic impact”). Petitioners challenge the Agency’s position by appealing to a competing norm of statutory construction: “[W]here ... Congress adopts a new law incorporating sections of a prior law, Congress normally can be presumed to have had knowledge of the interpretation given to the incorporated law, at least insofar as it affects the new statute.” Lorillard v. Pons, 434 U.S. 575, 581, 98 S.Ct. 866, 870, 55 L.Ed.2d 40 (1978). Accord Lindahl v. OPM, 470 U.S. 768, 782 & n. 15, 105 S.Ct. 1620, 1628 & n. 15, 84 L.Ed.2d 674 (1985); Haig v. Agee, 453 U.S. 280, 301 & n. 50, 101 S.Ct. 2766, 2779 & n. 50, 69 L.Ed.2d 640 (1981); Dart v. United States, 848 F.2d 217, 229 (D.C.Cir.1988). Thus, when Congress enacted section 3004(x) in 1984, petitioners assert, it adopted EPA’s contemporaneous interpretation of the scope of the Bevill Amendment, which included all solid waste from the smelting and refining of ores and minerals. See 45 Fed.Reg. at 76,619. In effect, petitioners advance a Chevron step one argument, i.e., that “Congress has directly spoken to the precise question at issue.” 467 U.S. at 842, 104 S.Ct. at 2781. They rely principally upon two points of legislative history in support of their position. First, Senator Randolph inserted into the record the following statement: [0]f course, we recognize that under the ongoing reexamination of what wastes the min