Opinion ID: 4020089
Heading Depth: 2
Heading Rank: 2

Heading: exclusion of certain units from mact analysis

Text: In the Major Boilers Rule, the EPA created subcategories based primarily on the fuel combusted. See 2013 Major Boilers Rule, 78 Fed. Reg. at 7,142. To qualify for certain subcategories, the EPA required that a source burn a fuel mixture comprised of only 10 per cent of the subcategorydefining fuel. See, e.g., id. at 7,193 (“Unit designed to burn solid fuel subcategory means any boiler . . . that burns . . . at least 10 percent solid fuel . . . in combination with liquid fuels or gaseous fuels.” (emphasis added)). Notwithstanding the low bar for inclusion, we conclude, and discuss at greater length below, see infra § IV.J, that the EPA reasonably exercised its discretion when it subcategorized boilers this way. 82 We cannot say the same about the EPA’s exclusion of certain high-performing units from its MACT-floor calculation. Although the EPA allowed sources that combust only 10 per cent of a subcategory-defining fuel to join that subcategory, it declined to consider emissions from any source that burned less than 90 per cent of the subcategorydefining fuel when determining the average emissions level of the best performing sources in setting MACT floors for existing sources. And when it set a subcategory’s MACT floors for new sources, the Agency declined to consider the emissions levels from any source that did not burn 100 per cent of the fuel. This disparate treatment makes a difference; several sources excluded from the MACT-floor determination were among the best performing sources (or, in some cases, the single best performing source) in that fuelbased subcategory. The CAA, however, demands that source subcategories take the bitter with the sweet. Section 7412 mandates, without ambiguity, that the EPA set the MACT floor at the level achieved by the best performing source, or the average of the best performing sources, in a subcategory. See 42 U.S.C. § 7412(d)(3)(A), (B). It thus follows that if the EPA includes a source in a subcategory, it must take into account that source’s emissions levels in setting the MACT floor. The Agency, however, claims discretion to omit from MACT-floor computation sources it considers dissimilar. In support, it cites section 7412(d)(3), which provides that MACT standards must be no less stringent than “the best controlled similar source, as determined by the [EPA].” Id. § 7412(d)(3) (emphases added). Our decision in Sierra Club II, 479 F.3d 875, however, forecloses this argument. In Sierra Club II, the EPA set MACT standards for brick and 83 ceramic kilns. Id. at 879. For some subcategories, the EPA based its MACT-floor determination on “the pollution control devices used by the second-best performers,” not the best performers. Id. (emphasis added). Although the EPA argued that it “reasonably construe[d] the term ‘best performing’ . . . to allow it to consider whether retrofitting kilns with a particular pollution control technology is technically feasible,” id. at 880 (alterations in original), we held that the EPA could not circumvent the requirement that it base the MACT floor “on the emission level actually achieved by the best performers (those with the lowest emission levels).” Id. at 880-81 (citing Cement Kiln, 255 F.3d at 861) (emphasis in original). We reach the same conclusion here. The EPA tries to distinguish Sierra Club II, arguing that the issue in that case “was whether [the] EPA could exclude all units using the most-effective emission control technique because it might not be applicable to all existing units”; however, “[h]ere, [the] EPA is excluding a test result that is unrepresentative of typical operations of units in the subcategory, and thus is inappropriate to use in establishing the MACT floor.” No. 11-1108 EPA Br. 81. But it makes no difference whether the EPA exempts from consideration units with certain highly effective technology or units with impressive test results driven by the fuel combination it combusts. Either approach contravenes our holding in Sierra Club II that the EPA cannot ignore “the emission level actually achieved by the best performers (those with the lowest emission levels)” in the subcategory. 479 F.3d at 880 (emphasis omitted). In any event, the EPA has not simply excluded aberrant test results; it has excluded an entire class of units—those burning less than 90 per cent of the subcategory’s fuel—even though every one of those units fits 84 the subcategory’s parameters. This is no different from what we rejected in Sierra Club II. The EPA insists that if a source is “unrepresentative of typical operations of units in the subcategory,” it is “inappropriate to use [it] in establishing the MACT floor.” No. 11-1108 EPA Br. 81. Not so. “The idea is to set limits that, as an initial matter, require all sources in a category to at least clean up their emissions to the level that their best performing peers have shown can be achieved.” Sierra Club I, 353 F.3d at 980 (citing 42 U.S.C. § 7412(d)(3)). For this reason, an unusually high-performing source should be considered; indeed its performance suggests that a more stringent MACT standard is appropriate. Accordingly, we vacate the MACT standards for all major boiler subcategories that would have been affected had the EPA considered all sources included in the subcategories.20