 United States Court of Appeals
         FOR THE DISTRICT OF COLUMBIA CIRCUIT



                    Decided May 31, 2019

                         No. 18-5179

       NATIONAL PARKS CONSERVATION ASSOCIATION,
                      APPELLANT

                              v.

     TODD T. SEMONITE, LIEUTENANT GENERAL, ET AL.,
                      APPELLEES


                 Consolidated with 18-5186


                 On Petitions for Rehearing


    Before: GARLAND, Chief Judge, and TATEL and MILLETT,
Circuit Judges.

    Opinion for the Court filed PER CURIAM.

     PER CURIAM: On March 1, 2019, this court held in the
clearest of terms that the U.S. Army Corps of Engineers had
violated the National Environmental Policy Act (NEPA)
when, without first preparing an environmental impact
statement, it issued a permit to the Virginia Electric and
Power Company (“Dominion”) to construct the Surry-Skiffes
Creek-Whealton project, consisting in relevant part of a series
                               2
of electrical transmission towers across the historic James
River. See National Parks Conservation Ass’n v. Semonite,
916 F.3d 1075, 1082–89 (D.C. Cir. 2019); see also Sierra
Club v. U.S. Army Corps of Engineers, 803 F.3d 31, 37 (D.C.
Cir. 2015) (“At the heart of NEPA is the procedural
requirement that federal agencies prepare . . . an
Environmental Impact Statement . . . .”). We vacated the
permit. See National Parks Conservation Ass’n, 916 F.3d
at 1089.
     Neither “downplaying the seriousness of the deficiencies
found by this Court” nor “request[ing] any change in the
opinion language directing the Corps to prepare an” EIS, the
Corps, joined by Dominion (collectively, “Petitioners”), now
seeks panel rehearing solely on the issue of remedy. Federal
Appellees’ Petition for Panel Rehearing (“Corps Petition”)
at 5, 9, 14 (alteration and internal quotation marks omitted).
Citing Allied-Signal, Inc. v. U.S. Nuclear Regulatory
Commission, 988 F.2d 146, 150–51 (D.C. Cir. 1993)
(explaining that, although vacatur is the default remedy to
correct defective agency action, the court may elect a different
remedy based on “the seriousness of the order’s deficiencies”
and “the disruptive consequences” of vacatur (internal
quotation marks omitted)), Petitioners urge us “to remand to
the agency without vacating the underlying permit,” Corps
Petition, at 14. In support, the Corps observes that when this
court decided the case it did not “have before it the recent
factual developments regarding completion of construction
and the disruption that vacating the permit could cause.” Id.
at 4. That, of course, is because neither petitioner bothered to
advise us that construction on the project had been completed
and the transmission lines electrified the week before we
issued our opinion.
                               3
     For their part, the National Parks Conservation
Association and the National Trust for Historic Preservation
(collectively, “Conservation Groups”) argue that the
Allied-Signal factors weigh in favor of maintaining the
vacatur, that Petitioners waived the argument they now make
by failing to raise it during the merits stage of the appeal, and
that Petitioners are judicially estopped from presenting this
claim based on representations they made to the district court
and this court in earlier stages of the litigation.
      In support of their estoppel argument, the Conservation
Groups point out that Petitioners’ position regarding the
appropriate remedy on appeal has changed during the course
of this litigation. To defeat the Conservation Groups’ motions
to enjoin construction of the towers, Petitioners assured the
district court that an injunction was unnecessary because if the
Conservation Groups succeeded on the merits—that is, if the
court ruled that the Corps was required to prepare an EIS—the
permit could be vacated and the towers correspondingly
removed. See, e.g., Federal Defendants’ Opposition to
Plaintiff’s Motion for Injunction Pending Appeal at 9,
National Parks Conservation Ass’n v. Semonite, No.
1:17-CV-01361 (D.D.C. June 25, 2018), ECF No. 115 (“[I]f
Plaintiff were able to succeed on the merits of its appeal and
satisfy the heavy legal burdens to establish entitlement to such
a remedy, the steel towers Dominion will place atop existing
foundations could be removed.”). The district court relied on
that representation. Over the Conservation Groups’ protests
that “construction of the towers will render the project a fait
accompli,” the court denied the motion for injunctive relief,
reasoning that “[s]hould it ultimately be determined that the
Army Corps of Engineers unlawfully issued the permit for the
project, the Court can order the towers removed.” Order at
4–5, National Parks Conservation Ass’n v. Semonite, No.
1:17-CV-01361 (D.D.C. July 3, 2018), ECF No. 117 (internal
                              4
quotation marks omitted). Petitioners made the same
guarantees to this court when opposing the Conservation
Groups’ motion for an injunction pending appeal. See, e.g.,
Dominion’s Response to Plaintiff-Appellant’s Emergency
Motion for an Injunction Pending Appeal at 16 (“[T]he towers
can be removed, and any preexisting views restored
completely . . . if [the Conservation Groups] prevail[] on
appeal.”); Federal Appellees’ Opposition to Motion for an
Injunction Pending Appeal at 22 (observing that the court has
the “power to order a project removed” where a “NEPA
analysis [is] legally inadequate” (internal quotation marks
omitted)). And we, too, denied the motion.
     As the Conservation Groups see it, Petitioners’ conduct
calls for the court to invoke judicial estoppel: “Now that [the
Conservation Groups] ha[ve] prevailed,” they observe,
“[Petitioners] take the opposite tack. Having argued
(successfully) that tower removal could be accomplished in
the event that [the Conservation Groups] ultimately succeeded
on their EIS claim, [Petitioners] now argue that [the
Conservation Groups are] not even entitled to the default
remedy provided by the [Administrative Procedure Act].”
National Parks Conservation Association’s Response to
Appellees’ Rehearing Petitions at 9. “[H]aving taken one
position to gain the substantial benefit of constructing a
project during ongoing litigation that otherwise would have
been prohibited, [Petitioners] cannot now advance a
contradictory position that would place [the Conservation
Groups] in the extremely prejudicial position of having
obtained a largely hollow victory.” Id.; see New Hampshire v.
Maine, 532 U.S. 742, 749 (2001) (“[J]udicial estoppel . . .
prevents a party from prevailing in one phase of a case on an
argument and then relying on a contradictory argument to
prevail in another phase.” (internal quotation marks omitted)).
                                5
     We find the foregoing more than a little troubling. Had
the Corps and Dominion said all along what they say now,
either the district court or this court might have enjoined
tower construction, in which case our consideration of
“disruptive consequences,” Allied-Signal, 988 F.2d at 150,
would focus not on shutting down and removing the towers,
but rather on prohibiting their construction—a very different
balance indeed. Moreover, having completed construction,
Petitioners now attempt to use it to place an even heavier
thumb on the scale, as they represent that they have invested
$400 million in tower construction, as compared to the
“$178.7 million cost asserted in the Corps’ [Environmental
Assessment].” National Parks Conservation Association’s
Response to Appellees’ Rehearing Petitions at 14; see also
Dominion’s Petition for Rehearing or Rehearing En Banc
at 15.
     All this said, we nonetheless believe the best course of
action is to remand the case to the district court to consider, in
view of Petitioners’ and the Conservation Groups’ arguments,
whether vacatur remains the appropriate remedy, including
whether Petitioners have forfeited or are judicially estopped
from now opposing vacatur. That court is best positioned to
order additional briefing, gather evidence, make factual
findings, and determine the remedies necessary to protect the
purpose and integrity of the EIS process. See, e.g., Chambers
v. NASCO, Inc., 501 U.S. 32, 44–45 (1991) (noting that
district courts possess “the ability to fashion an appropriate
sanction for conduct which abuses the judicial process”).
                              6
    Accordingly, without expressing a view as to the
appropriate outcome of the district court’s inquiry, we remand
the case for further proceedings consistent with the court’s
opinions in this case.
                                                  So ordered.
