At oral argument, petitioners suggested "alternative 4," which involves expansion of SDF over an uninhabited landfill to the south. In the FEIS, the FAA summarized alternative 4 as follows:

This alternative calls for installation of an east-west parallel runway south of Standiford Field and parallel to the existing east-west runway (11/29). The distance between the two runways would exceed 4,300 feet, allowing fully independent, simultaneous operations during both good and bad weather based on FAA rules. However, it would require closing the landfill in the area of Outer Loop and I-65 operated by Waste Management of Kentucky, Inc. Major portions of the landfill would have to be stabilized and/or removed. Several businesses would be displaced to accommodate the western end of the runway and taxiway connection to the existing airport. The runway and taxiway facility would be built to accommodate the function of Slop Ditch, a major drainage channel splitting the existing landfill site. It is possible that the interchange of Outer Loop with I-65 would constitute an obstruction within the required clear zone, requiring elevation of the east end of the runway on fill material. J.A. at 3615.

Finally, our approval of the FAA's noise methodology also means that the FAA is required neither to reopen public comment following publication of SEL data nor prepare a supplemental EIS analyzing the impact of increased single event noise. Even if we were to consider the SEL data, however, the agency's determination of whether new information requires the preparation of a supplemental EIS is also subject to review under the arbitrary and capricious standard. Marsh v. Oregon Natural Resources Council, 490 U.S. 360, 375-76, 109 S.Ct. 1851, 1860, 104 L.Ed.2d 377 (1989). Given that the FAA did in fact discuss the SEL data and determined that the information did not alter its conclusions regarding the noise impacts of the LAIP, we do not find that the agency in any way abused its discretion.

Petitioners contend also that the FAA violated the NEPA by "segmenting" the analysis of hazardous wastes and transportation. Petitioners' criticism of the FAA's analysis of the hazardous substances impacts of the LAIP hinges on the perceived lack of a complete remediation or mitigation plan. In so arguing, petitioners run afoul of the Supreme Court's directive in Robertson v. Methow Valley Citizens Council, 490 U.S. 332, 109 S.Ct. 1835, 104 L.Ed.2d 351 (1989).

In Robertson, the Supreme Court unanimously reversed the Ninth Circuit's holding that NEPA required a complete mitigation plan to be developed and included in an environmental impact statement. The Court stated that

it would be inconsistent with NEPA's reliance on procedural mechanisms -- as opposed to substantive, result-based standards -- to demand the presence of a fully developed plan that will mitigate environmental harm before an agency can act.

We thus conclude that the Court of Appeals erred, first, in assuming that "NEPA requires that 'action be taken to mitigate the adverse effects of major federal actions,'" and, second, in finding that this substantive requirement entails the further duty to include in every EIS "a detailed explanation of specific measures which will be employed to mitigate the adverse impacts of a proposed action."

As for the "transportation impact" -- that is, the closing of Crittenden Drive -- the FEIS and ROD make it clear that the drive will be closed. Reconstruction, if it takes place at all, will not take place for at least ten years, and plans for reconstruction have not yet been determined. Under the principles in Robertson, the FAA may properly delay consideration of the environmental impacts of this speculative project and, instead, treat the drive as closed. See J.A. at 1925-38 (discussing the impact of closing Crittenden Drive).

Petitioners contend also that the FAA violated the NEPA by failing to consider and analyze the impact of the proposed acquisition and destruction of the Standiford, Prestonia, and Highland Park neighborhoods as part of the proposed action alternative. They allege that the draft FEIS described the demolition of 1,300 units in the three neighborhoods adjacent to the airport as urban renewal action that would occur without regard to the airport expansion and, therefore, evaluated the destruction of these residential areas as part of the no-action alternative. Upon the decision of the Kentucky Supreme Court that such acquisition was undertaken in an unconstitutional manner, petitioners contend that the FAA was required to reopen the public hearing process and receive comment on the impact this decision has on the analysis of the consequences of the airport expansion.

With or without the expansion of SDF, the governments of Louisville and Jefferson County have been and remain committed to removing certain residential properties from the three neighborhoods near SDF that are currently heavily impacted by aircraft noise. They have demonstrated that commitment by moving ahead with a land acquisition program -- using strictly local money -- long before there was any assurance that the airport project would, or could, be built. That program was already 69% complete in January 1991. It is fully discussed in the FEIS, just as the Prestonia decision is fully discussed in the ROD.

Petitioners essentially advance another "segmentation" argument, contending that the FAA characterized the land acquisition as a separate project in order to avoid performing the requisite environmental analysis. Petitioners cannot succeed with a segmentation argument, however, because (1) the FAA performed the environmental analysis, and (2) even in the absence of any environmental analysis, the local land-acquisition program has independent utility within the meaning of Historic Preservation Guild v. Burnley, 896 F.2d 985, 990-92 (6th Cir.1989). [FN2]

[FN 2] Because of our disposition of this issue, we offer no opinion as to what effect, if any, the withdrawal of the Prestonia, Highland Park, and Standiford neighborhood associations as parties to the instant petition has upon the standing of the remaining neighborhoods to contest this issue.

Petitioners contend also that the FAA violated the NEPA by failing to consider the alternatives. For an agency to conclude that there is no "feasible" alternative, "the Secretary must find as a matter of sound engineering it would not be feasible to build the [project] along any other route." Citizens to Preserve Overton Park, Inc. v. Volpe, 401 U.S. 402, 411, 91 S.Ct. 814, 821, 28 L.Ed.2d 136 (1971). Feasible alternatives may nonetheless be rejected if they present "unique problems" or cause extraordinary costs and community disruption. Id. at 413, 91 S.Ct. at 822.

The two alternatives ultimately considered in the FEIS -- the LAIP and the no action alternative -- were arrived at from about two dozen initially considered. Working Paper No. 1, "Airport Improvement Alternatives," presented discussions of alternative facility improvements that had a reasonable expectation of implementation, grouped in five categories of operation. Five potential airport configurations were then selected for detailed evaluation and their costs and effects were presented in Schimpeler-Corradino Technical Report No. 2, "Evaluation of Alternatives," and No. 3, "Selection of Preferred Alternative." These five are depicted in the FEIS. They include the two configurations that petitioners urge would be more appropriate -- that is, the only two variations that would avoid taking the historic properties of James Lowell Elementary School, Grove Park and Highland Park Community Center, and the residence at 2111 South Park Road. A thorough discussion of the alternatives is presented in the FEIS, and for each, the FEIS includes a graphic configuration, an engineering analysis, and an explanation of why the alternative was either imprudent or infeasible. In addition to the FEIS discussion of these alternatives, the administrative record is replete with extensive documentation of a very detailed evaluation. The FAA selected the fifth alternative as the only practical and feasible alternative.

The reasons for deeming the other alternatives infeasible were fully explained. The FAA reasonably rejected several of the alternatives that presented severe engineering requirements. Other alternatives were found to be imprudent for reasons including their high cost, safety hazards, operational difficulties, and disruptions to landfills and noise-sensitive areas. In short, each was rejected because it presented unique problems and would not accomplish the goal of increasing capacity at SDF. By focusing on the ROD and FEIS, which represent only the final stage in the lengthy review process, petitioners ignore the enormous record evidence on feasibility.

For the foregoing reasons, the Secretary of Transportation's approval, through the Federal Aviation Administration, of the Louisville Airport Improvement Plan is AFFIRMED, and accordingly, the petition for review is DENIED.