Opinion ID: 4020089
Heading Depth: 3
Heading Rank: 1

Heading: NACWA, 734 F.3d 1115 (D.C. Cir. 2013)

Text: Based on the limitations inherent in stack testing, the EPA concluded that it could not set MACT floors based on that testing alone. It began using the UPL to account for the HAPs-emissions variety that stack-testing data do not reflect. See NACWA, 734 F.3d at 1122. The Agency did so in several rules promulgated in 2011, including not only the Major Boilers Rule and the CISWI Rule but also the Sewage Sludge Incinerator Rule addressed in NACWA. See id. In that case, the petitioners challenged the EPA’s UPL use, arguing that the Agency failed to establish that the UPL fairly represented the “average emissions limitation achieved” by the best performing sources to set the Sewage Sludge Incinerator MACT floors and, accordingly, was “unlawful and arbitrary.” Id. at 1130. We agreed in part. See id. at 1119. Specifically, we struggled to pin down the EPA’s precise interpretation of the phrase “average emissions limitation achieved by the best performing 12 percent of units.” Id. at 1142-43 (quoting 42 U.S.C. § 7429(a)(2)).23 As best we could tell, the EPA defended its use of the UPL as follows: “[b]ecause the [UPL] represents the value which [the EPA] 22 See also Page Mem. 5 (“[E]ven single three run tests, which are performed over a short period of time, typically show different emissions levels during each individual test run.”). 23 See also NACWA, 734 F.3d at 1142 (“[I]t seems EPA has adopted yet another interpretation of the phrase ‘average emissions limitation achieved by the best performing 12 percent of units.’” (emphasis added)). 87 can expect the mean (i.e., average) of three future observations (3-run average) to fall below, based upon the results of the independent sample size from the same population, the [UPL] reflects average emissions.” Id. at 1142 (quoting Standards of Performance for New Stationary Sources and Emission Guidelines for Existing Sources: Sewage Sludge Incineration Units, 76 Fed. Reg. 15,372, 15,389 (Mar. 21, 2011)) (emphasis added) (some alteration in original). In our view, however, “the word ‘average’ . . . seems to mean the average emissions limitation that the existing population of the best-performing 12 percent of incinerators has achieved.” Id. (emphases added). Despite these doubts, we reasoned that the EPA could have “plausibl[y]” concluded that the UPL represents the “average emissions limitation achieved” by the best performing sources. Id. at 1143. That said, we were not willing to assume the EPA’s responsibility of “supply[ing] a reasoned basis” for its UPL use. Id. (quoting Bowman Transp., Inc. v. Ark.-Best Freight Sys., Inc., 419 U.S. 281 (1974)). For that reason, we remanded—but did not vacate, see id. at 1161—the UPL portion of the Sewage Sludge Incinerator Rule and ordered the EPA to “clarify how the [UPL] represents the average emissions limitation achieved by the best performing 12 percent.” Id. at 1143 (internal quotation marks omitted).24 24 See also NACWA, 734 F.3d at 1151 (“[W]hile we determine that [the] EPA’s use of the [UPL] may be lawful, we are remanding this portion of its rulemaking for further explanation on the issue[] of how the upper prediction limit represents the average emissions limitation achieved . . . .” (internal quotation marks omitted)). 88 Because the EPA also used the UPL in the Major Boilers Rule and the CISWI Rule, the Agency moved for a limited remand of the current petitions so that it could include its revised UPL explanation in the administrative records of these two regulations.25 See Page Mem. 2. On July 14, 2014, the EPA published a fifteen-page memorandum authored by Stephen D. Page, the EPA Director of Air Quality Planning and Standards (Page Memorandum), in response to NACWA. See id. at 1. The EPA’s current explication of the UPL is now before us.26 25 In NACWA, we had other problems with the EPA’s use of the UPL. Specifically, the EPA had explained that “a smaller dataset may have greater variability, and thus a higher [UPL].” NACWA, 734 F.3d at 1144. We instructed the EPA not only to explain its use of the UPL in general but also to “explain why the [UPL] could still be considered accurate given a small dataset” in particular. Id. at 1144-45 (emphasis added). In its remand motion, the EPA represented that it could “adequately explain why [its] use of the UPL in general is consistent with Clean Air Act requirements through a remand of the record for a limited time” but that “the question of whether the UPL is an appropriate statistical method for small data sets requires more analysis . . . [along with] additional notice and comment rulemaking.” No. 11-1108 Mot. for Remand 9, 13 (Feb. 28, 2014). We agreed and, for this reason, the only issue we decide today is whether the EPA carried its burden of establishing, as a general matter, that the UPL reasonably estimates the average emissions level achieved by the best performing source or sources to set MACT floors. 26 The Environmental Petitioners urge us to ignore the Page Memorandum, insisting that it “provide[s] a series of new interpretations and assertions that, rather than ‘explaining’ the prior record, instead contradict and revise the agency’s earlier position,” in contravention of NACWA and the scope of the remand the Agency requested regarding the Major Boilers Rule and the CISWI 89