Court Opinion

ID: 4908296
Source: CourtListenerOpinion
Date Created: 2021-09-03 20:01:15.640353+00
Date Added: 2024-06-11T08:13:14.625999
License: Public Domain

In the

    United States Court of Appeals
                 For the Seventh Circuit
                    ____________________
Nos. 20-1711 & 20-1793
VON DUPRIN LLC,
                               Plaintiff-Appellee, Cross-Appellant,
                                 v.

MAJOR HOLDINGS, LLC and
MAJOR TOOL AND MACHINE, INC.,
                          Defendants-Appellants, Cross-Appellees,

                                and

MORAN ELECTRIC SERVICE, INC.,
                                         Defendant, Cross-Appellee.
                    ____________________

        Appeals from the United States District Court for the
         Southern District of Indiana, Indianapolis Division.
        No. 1:16-cv-01942 — Tanya Walton Pratt, Chief Judge.
                    ____________________

   ARGUED MARCH 30, 2021 — DECIDED SEPTEMBER 3, 2021
                    ____________________

   Before KANNE, BRENNAN, and SCUDDER, Circuit Judges.
    SCUDDER, Circuit Judge. This is a complex environmental
cleanup case out of Indianapolis, Indiana. Over several
2                                       Nos. 20-1711 & 20-1793

decades, owners and operators of industrial facilities dis-
posed of chemical solvents used in manufacturing processes.
The solvents have degraded over time and have seeped into
the groundwater and soil in the surrounding residential area.
Investigations showed that vapors emitting from the under-
ground contamination have intruded into homes and a local
park.
    Von Duprin LLC, whose predecessor in interest manufac-
tured security hardware and once owned property in the area,
undertook cleanup eﬀorts and then sought to recover some of
those costs as well as future remediation costs. Von Duprin
sued former and current owners and operators of adjoining
properties under the Comprehensive Environmental Re-
sponse, Compensation, and Liability Act—a federal environ-
mental statute often shorthanded as CERCLA. Following a
bench trial, the district court found that Von Duprin and two
other former or current owners and operators in the area bore
responsibility for portions of the environmental harm. The
court then assigned liability among and between all three par-
ties. Before us now are an appeal and cross-appeal from
lengthy proceedings in the district court.
    While we see no error in many of the district court’s rul-
ings, we vacate the court’s threshold determination under
§ 107(a) of CERCLA that liability for remediating the environ-
mental harm is divisible—capable of being apportioned on
the basis of principles of causation—among and between the
parties to this litigation. In the end, then, we aﬃrm in part and
vacate and remand in part for additional proceedings.
Nos. 20-1711 & 20-1793                                      3

                              I
   A. The Properties at Issue
   The environmental harm developed over at least the last
50 years. The four relevant and adjacent properties, each in
northeast Indianapolis, have changed hands over the years.
    We start with the Von Duprin Property. Von Duprin LLC’s
predecessor, Von Duprin Inc., owned the property for over 40
years and during that time manufactured security hardware
and safety products. The ﬁrm used degreasers and a variety
of chemical products, including trichloroethylene (TCE) and
perchloroethylene (PCE). Operations ceased in 1986, and a
manufacturer named Threaded Rod Company, Inc. acquired
the Von Duprin Property in 1987.
    Next up is the Moran Property. Moran Electric Service
Inc., a company that used degreasers as well as TCE and other
cleaning agents in connection with repairing electrical mo-
tors, owned and operated this property from 1946 to 1996. In
2005, a company called Major acquired the Moran Property.
   Now the Ertel Property. Ertel Manufacturing, a manufac-
turer of automotive engine parts, owned this property from
1917 to 1998. The ﬁrm used chlorinated solvents like TCE and
PCE in its manufacturing processes. The Ertel Property
changed hands in 1998, only later to be abandoned. In 2007
Major leased the Ertel Property from the City of Indianapolis.
Major acquired full ownership in 2013.
   The Zimmer Paper Property, itself subdivided into the
Zimmer Paper Facility and the Zimmer Packaging Facility, is
the fourth property. Zimmer Paper Products, Inc. owned the
property from 1986 to 2006, during which time the company
used and disposed of chemical solvents. These properties
4                                      Nos. 20-1711 & 20-1793

were owned and operated by Moran from 1967 to 1984. Major
acquired the Zimmer Paper Facility in 2007 and later acquired
the Zimmer Packaging Facility in 2013.
    Major, which we use for simplicity in referring to Major
Holdings LLC and Major Tool & Machine, is the current
owner of the Ertel Property, Moran Property, and Zimmer Pa-
per Property. No one alleges that Major released any hazard-
ous materials at any of its properties, but current owners or
operators of a site where hazardous materials were released
may be held liable under CERCLA without having caused a
release.
     So the overall ownership history breaks down this way:
         Properties           Former Owner(s)       Current
                                                    Owner
    Von Duprin Property      Von Duprin LLC        Threaded
                                                   Rod
    Moran Property           Moran Electric        Major
                             Service
    Ertel Property           Ertel Manufacturing   Major
    Zimmer Paper             Moran Electric        Major
    Property (divided into   Service
    the Zimmer Paper         Zimmer Paper
    Facility and the         Products
    Zimmer Packaging
    Facility)
    All agree that, at various times over the twentieth century,
chlorinated solvents, including PCE and TCE, were dumped
at and around the Von Duprin, Moran, Ertel, and Zimmer
Properties. These solvents are toxic and over time they seeped
Nos. 20-1711 & 20-1793                                          5

into the soil and groundwater, eventually commingling into a
groundwater plume—a collection of groundwater mixed
with hazardous contaminants underground—which ﬂows
from northeast (where the properties are located) to south-
west, covering approximately three-quarters of a mile. Of par-
ticular concern is that vapor emissions from the plume can
migrate upwards from the groundwater and through the soil,
resulting in vapor intrusion into structures. About 40 homes
and an indoor facility at the public park have experienced this
intrusion.
   B. Von Duprin’s Lawsuit
    After several environmental assessments and investiga-
tions of the Von Duprin Property, the Indiana Department of
Environmental Management or IDEM, determined in March
2009 that soil and groundwater at and around the property
had been contaminated by chlorinated solvents. In 2013 IDEM
informed Von Duprin that it could be a potentially responsi-
ble party or PRP under Indiana law. Von Duprin then began
its own investigation into the contamination. In time the com-
pany entered Indiana’s cleanup program and performed sub-
stantial remediation in the area. After it, too, received a poten-
tial liability notice from IDEM and began to take remedial ac-
tion, Threaded Rod, the current owner of the Von Duprin
Property, ﬁled a suit against Von Duprin and others to re-
cover costs. That case later settled.
    Von Duprin has continued to undertake remediation ef-
forts at a cost of $3.2 million. In 2016 the company invoked
§ 107(a) of CERCLA and turned to federal court to recover
those costs from current and former owners of adjacent prop-
erties—Moran, Zimmer, and Major.
6                                       Nos. 20-1711 & 20-1793

    Moran and Major responded by going on the oﬀensive
and ﬁling counterclaims and crossclaims against Von Duprin
under § 113(f) of CERCLA. Zimmer never appeared or re-
plied to the original complaint, so the district court entered a
default against the company under Federal Rule of Civil Pro-
cedure 55(a).
    C. An Overview of CERCLA
   Some background on CERCLA is essential to understand-
ing the district court’s decision and issues before us on appeal.
    Over many decades, Congress has created legal mecha-
nisms to encourage cleanup and continued stewardship of
real property. A prime example came with the enactment of
CERCLA in 1980. Congress designed the statute to “promote
the timely cleanup of hazardous waste sites and to ensure that
the costs of such cleanup eﬀorts were borne by those respon-
sible for the contamination.” Burlington Northern & Santa Fe
Ry. Co. v. United States, 556 U.S. 599, 602 (2009) (cleaned up).
The statute operates in part by encouraging, and directly
providing the vehicle for, private parties to invest in environ-
mental response, including remediation, and then to recover
at least part of those response costs from other potentially re-
sponsible parties or PRPs.
    In United States v. Atlantic Research Corporation, the Su-
preme Court held that § 107(a) of CERCLA, codiﬁed at 42
U.S.C. § 9607(a), provides PRPs who incurred response costs
with a cause of action to recover certain of those costs from
other PRPs. See 551 U.S. 128, 131, 139 (2007). To establish a
claim for cost recovery under § 107(a), a plaintiﬀ must show
that (1) the site in question is a “facility”; (2) the defendant
qualiﬁes as a PRP; (3) the facility experienced a release or
Nos. 20-1711 & 20-1793                                        7

threatened release of hazardous substances; and (4) the plain-
tiﬀ incurred costs consistent with the National Contingency
Plan in responding to the release. See Env’t Transp. Sys., Inc.,
v. ENSCO, Inc., 969 F.2d 503, 506 (7th Cir. 1992).
    Congress deﬁned PRPs to include four entities: current
owners and operators of a site that experienced a disposal of
hazardous material, past owners or operators at the time of
the release, persons who arranged for disposal of a hazardous
substance at a site, and parties who transported a hazardous
substance to a site. See 42 U.S.C. § 9607(a)(1)–(4). Everyone
agrees that each party to this litigation qualiﬁes as a PRP un-
der CERCLA.
    Joint and several liability is the norm for PRPs under
§ 107(a). The exception is divisible liability—commonly called
apportioned liability—where liability is assigned to PRPs ac-
cording to the portion of the underlying environmental harm
each caused. See Burlington Northern, 556 U.S. at 613.
    PRPs who ﬁnd themselves sued under § 107(a) often ﬁle a
counterclaim against the original plaintiﬀ on the basis that the
party is itself a PRP who caused part of the harm and thus
should contribute to any ultimate remediation liability. These
so-called contribution counterclaims proceed under § 113(f)
of CERCLA, which authorizes the allocation of liability based
on “such equitable factors as the court determines are appro-
priate.” 42 U.S.C. § 9613(f)(1).
    At this point, what is essential to recognize is that appor-
tioned (divisible) liability and allocated liability are not one
and the same under CERCLA. To the contrary, they are dis-
tinct, with apportioned liability imposed on the basis of
8                                      Nos. 20-1711 & 20-1793

principles of causation and allocated liability the product of
an application of equitable factors.
    Two more background points help frame the issues on ap-
peal. First, not all remediation costs are eligible for recovery
under § 107(a). Rather, Congress has limited recovery costs to
those incurred consistent with the National Contingency Plan
or NCP. See 42 U.S.C. § 9607(a)(4)(B). The NCP establishes
how private parties can best perform removal and remedial
actions to ensure the achievement of CERCLA-quality
cleanup. See 40 C.F.R. § 300.
    Second, CERCLA provides an aﬃrmative defense to reme-
diation liability to PRPs who did not release hazardous mate-
rials themselves but remain potentially liable by virtue of be-
ing a current owner of a site where a prior release occurred.
Added in 2002, Congress called this defense the “bona ﬁde
prospective purchaser” or BFPP defense. See 42 U.S.C.
§ 9607(q)(1)(C). To qualify, a PRP must, in connection with the
original purchase of the property in question, and among
other things, make “all appropriate inquiries into the previ-
ous ownership and uses of the facility in accordance with gen-
erally accepted good commercial and customary standards
and practices.” 42 U.S.C. § 9601(40). In that way, the BFPP de-
fense shields from CERCLA liability those who invest in con-
taminated lands and exercise diligence, do not impede
cleanup eﬀorts, and meet ongoing obligations.
    D. Summary Judgment
    After a period of initial discovery, the parties ﬁled cross
motions for summary judgment. The district court’s ruling on
the divisibility of remediation liability—whether the norm of
joint and several liability for PRPs should apply or instead
Nos. 20-1711 & 20-1793                                      9

whether each PRP should bear responsibility to the degree
they caused the underlying environmental harm—is a sub-
stantial issue on appeal. In granting in part Moran and Ma-
jor’s motions for summary judgment, the district court deter-
mined that CERCLA liability was divisible and thus should
be apportioned among and between the PRPs.
    The district court’s reasoning rested on two abbreviated
observations. First, the court observed (without much accom-
panying explanation) that the harm caused by the PRPs (Von
Duprin, Major, Moran, and Zimmer) was “theoretically capa-
ble of apportionment” and therefore divisible among them.
From there, and second, the district court pointed to Moran’s
expert witness, Dr. Adam Love, and, again without much
elaboration, observed that there was a “reasonable basis for
apportionment.” Who caused what harm and how much each
PRP, including Von Duprin, should contribute to the overall
remediation costs would, the district court concluded, be de-
cided at a bench trial.
   At summary judgment the district court also concluded
that Major was a BFPP and thus could not be held liable for
response costs that Von Duprin (as the plaintiﬀ) sought to re-
cover relating to the Moran Property and Zimmer Packaging
Facility.
   E. The District Court’s Bench Trial
    A six-day bench trial ensued in the summer of 2019. A bat-
tle of competing experts—all oﬀering diﬀerent perspectives
on which PRP caused what portion of the overall environ-
mental harm—deﬁned much of the trial. Other witnesses tes-
tiﬁed about methods for allocating liability and whether the
10                                     Nos. 20-1711 & 20-1793

remediation costs incurred by Von Duprin were consistent
with the National Contingency Plan.
   The district court’s ultimate Findings of Fact and Conclu-
sions of Law included these key rulings:
    Recoverable Costs. The district court evaluated what portion
of Von Duprin’s costs were incurred consistent with the NCP
and therefore recoverable under § 107(a) of CERCLA. The
court concluded that $1.7 million of the $3.2 million Von
Duprin originally sought was recoverable, excluding the $1.5
million settlement with Threaded Rod from a previous law-
suit and $39,000 for the costs related to IDEM oversight.
    Apportionment of Liability. The district court began by re-
newing its prior observation (from summary judgment) that
the environmental harm was “theoretically capable of appor-
tionment.” It then found that, based on the evidence pre-
sented at trial, a “reasonable basis for apportionment exists.”
The court did so by crediting Moran’s expert Dr. Adam Love’s
testimony as to how the harm could be apportioned among
the properties—even while noting that the nature of the con-
tamination made it impossible to diﬀerentiate the chemical
compounds once they enter the groundwater plume and
eventually vaporize.
    In a section of its Conclusions of Law labeled “Apportion-
ment,” the district court held that Major was liable under
§ 107(a) as the current owner of the Ertel Property and Zim-
mer Paper Facility. Von Duprin, the court further concluded,
was liable as owner of the Von Duprin Property at the time of
a hazardous release. Moran was liable too, because it owned
the Moran Property at the time of a release. Since no party
Nos. 20-1711 & 20-1793                                           11

oﬀered evidence of a release when Zimmer owned the facil-
ity, the district court assigned no liability to it.
    Allocation of Liability. In a section labelled “Allocation,” the
district court then performed what it called “equitable alloca-
tion” by applying a series of factors, including the distin-
guishability of each party’s hazardous waste, the amount of
that waste, the toxicity of the contaminants at issue, the de-
gree of involvement of the parties in generating the waste, the
extent of each party’s cooperation with environmental au-
thorities to mitigate harm, and the overall care taken by each
party in handling the hazardous waste. These factors are com-
monly called the “Gore factors,” named after then-Congress-
man Albert Gore who proposed them as an amendment to a
1980 Superfund bill. See Env’t Transp. Sys, 969 F.2d at 508.
    After listing these Gore factors, but without any explana-
tion as to whether or how each factor played into its allocation
analysis, the district court “apportioned” the response costs
as follows: 50% to the Von Duprin Property, 10% to the Ertel
Property, 20% to the Zimmer Paper Property, and 20% to the
Moran Property. Each party was held responsible for 100% of
the harm attributed to the property or properties that they
once owned or now own. The district court then took those
percentages and applied them to the total amount of Von
Duprin’s recoverable costs—$1.7 million—and found that
Von Duprin was responsible for $850,000, Major for $510,000,
and Moran for $340,000. The district court considered the
cross- and counterclaims ﬁled by the parties to be resolved by
these liability allocations.
   From there the district court ruled on Von Duprin’s re-
quest for a declaratory judgment entitling it to recover antici-
pated future remediation costs related to ongoing cleanup
12                                     Nos. 20-1711 & 20-1793

contamination at the adjoining properties. The court found an
award of future costs warranted because the company had es-
tablished its right to recover from the other PRPs for past re-
sponse costs. The district court therefore awarded Von
Duprin future costs in an amount to be determined based on
the same allocation percentages of liability for past costs
among the parties, conditioned on the company proving that
subsequent costs were both incurred consistent with the NCP
and related to contamination at the surrounding properties.
     Major’s BFPP Defense. The district court further considered
Major’s request for a BFPP defense. At summary judgment,
the district court had concluded that Major was a BFPP (and
therefore shielded from liability under § 107(a)) for any harm
arising from the Moran Property and Zimmer Packaging Fa-
cility. Based upon the evidence presented at trial, however,
the district court reached the opposite conclusion for Major’s
two other properties, the Ertel Property and Zimmer Paper
Facility. Major was liable, the district court continued, for
harm resulting from those two properties because the com-
pany could not show that it had satisﬁed the “all appropriate
inquiries” requirement of the BFPP defense.
   Remaining State Law Claims. Finally, the district court sum-
marily disposed of Von Duprin’s state law claims, observing
that ruling in the company’s favor on those claims would
amount to a prohibited double recovery.
     F. Major’s Appeal and Von Duprin’s Cross-Appeal
   Major appealed and Von Duprin ﬁled its own cross-ap-
peal.
   Major appeals the district court’s decision to deny it the
beneﬁt of the BFPP defense to liability for its ownership of the
Nos. 20-1711 & 20-1793                                         13

Zimmer Paper Facility and the Ertel Property. Major also
maintains that Von Duprin failed to prove its response costs
were incurred consistent with the NCP. Finally, Major chal-
lenges the district court’s calculation of damages, contending
that the district court conﬂated the allocation and apportion-
ment processes, resulting in a damages award unsupported
by the evidence.
    Von Duprin cross-appealed, arguing that the district
court’s liability assignment erred at an earlier step: it should
never have concluded that the harm was capable of appor-
tionment. In Von Duprin’s view, the district court should
have held the defendants jointly and severally liable. At a
more granular level, Von Duprin also challenges the district
court’s failure to exclude Dr. Love’s testimony as unreliable.
    For its part, Moran asks us to aﬃrm the district court in
full.
                                II
    We begin with a word on appellate jurisdiction. Upon
docketing Major’s appeal and Von Duprin’s cross-appeal, we
questioned whether the case had reached ﬁnality in the dis-
trict court and directed the parties to brief the question. What
concerned us was that the district court’s judgment made no
mention of Zimmer’s default, how the court resolved Moran
and Major’s counterclaims, and the amount of prejudgment
interest owed Von Duprin as part of its damages award. In
these ways, the district court’s judgment was deﬁcient, as it
invited the impression that the court had entered a partial
judgment under Federal Rule of Civil Procedure 54(b) and
thus not resolved all claims against all parties. See Gen. Ins.
Co. of America v. Clark Mall Corp., 644 F.3d 375, 378–80 (7th Cir.
14                                     Nos. 20-1711 & 20-1793

2011) (explaining scenarios in which 54(b) judgments provide
suﬃcient ﬁnality for purposes of appellate jurisdiction).
    Aided by the parties’ brieﬁng of the ﬁnality question, we
are conﬁdent in our jurisdiction. The district court’s ﬁnal
judgment order expressly accounted for 100% of the allocated
liability by assigning amounts owed to the pertinent parties,
thereby necessarily resolving Von Duprin’s primary claim
under § 107(a) as well as Moran and Major’s counterclaims for
contribution under § 113(f). We interpret the district court’s
silence on Zimmer to mean—as everyone agrees—that Zim-
mer, despite its default, owes nothing under the terms of the
judgment. To be sure, the district court should have entered
formal default judgment against Zimmer under Rule 55. And
while the district court also should have speciﬁed the pre-
judgment interest owed Von Duprin, the failure to do so does
not indicate a lack of ﬁnality because the computation is
“readily ascertainable from the record through only a minis-
terial calculation” and, even more, the docket shows that Mo-
ran has since paid the amount owed. Student Loan Marketing
Ass’n v. Lipman, 45 F.3d 173, 177 (7th Cir. 1995).
    In these circumstances, then, we have no doubt the case
reached ﬁnality in the district court and that we may proceed
to the merits of the questions presented on appeal.
                              III
    On the merits, we start with Von Duprin’s challenge to the
district court’s threshold determination at summary judg-
ment that remediation liability should not be joint and several
but instead apportioned among Major, Moran, and Zimmer
as the PRPs according to the environmental harm caused by
each company. Major challenges the district court’s resolution
Nos. 20-1711 & 20-1793                                        15

of its counterclaim seeking contribution from Von Duprin un-
der § 113(f) of CERCLA for its own share of the remediation
liability. Major sees the district court’s ultimate allocation of
liability as unsupported by the evidence presented at the
bench trial.
    Both Von Duprin and Major are right to ﬁnd fault with the
district court’s liability determinations. We see two errors.
First, the district court applied incorrect substantive and pro-
cedural standards in concluding at summary judgment that
the environmental harm and attendant CERCLA liability
could be apportioned. Second, after the bench trial, the district
court conﬂated the concepts of apportionment and allocation
and left unexplained the factors guiding its ultimate assign-
ments of liability. These two errors interrelate in ways that
leave us no choice but to vacate the district court’s judgment
and to remand for further proceedings.
   A. Apportionment at Summary Judgment
   Section 107(a) of CERCLA imposes “strict liability” on
PRPs for response costs resulting from a release of hazardous
materials. Burlington Northern, 556 U.S. at 608. While the stat-
utory text is silent on the scope of liability, the Supreme Court
has explained that Congress intended that question to “‘be
determined from traditional and evolving principles of com-
mon law.’” Id. at 613 (quoting United States v. Chem-Dyne
Corp., 572 F. Supp. 802, 808 (S.D. Ohio 1983)).
   The primary guideposts come from the Restatement (Sec-
ond) of Torts. And we know from the Restatement that
“where two or more persons cause a single and indivisible
harm, each is subject to liability for the entire harm.” Chem-
Dyne, 572 F. Supp. at 810 (citing Restatement (Second) of
16                                     Nos. 20-1711 & 20-1793

Torts, § 875). The imposition of joint and several liability
holds each party responsible for the entirety of the harm. See
id.
    The Restatement explains that liability may be divided—
or apportioned—“when two or more persons acting inde-
pendently caused a distinct or single harm for which there is
a reasonable basis for division according to the contribution
of each,” with each responsible party being “subject to liabil-
ity only for the portion of the total harm that he has himself
caused.” Id. (citing Restatement (Second) of Torts § 433A). Be-
cause “[n]ot all harms are capable of apportionment,” the Su-
preme Court has emphasized that “CERCLA defendants
seeking to avoid joint and several liability bear the burden of
proving that a reasonable basis for apportionment exists.”
Burlington Northern, 556 U.S. at 614. The facts and evidence
must permit a “reasonable basis” for dividing liability among
PRPs, as “arbitrary apportionment for its own sake” is incon-
sistent with CERCLA’s liability scheme. See id. at 614 (cita-
tions omitted).
    As a practical matter, joint and several liability often re-
ﬂects the norm in complex environmental cleanup cases be-
cause most circumstances reveal numerous disposers of waste
over long periods of time where after-the-fact identiﬁcation of
who contributed what and thus who caused what portion of
the present-day harm at issue is exceptionally diﬃcult to as-
certain with reliability. A leading case in this area—Chem-
Dyne, from which the Supreme Court took direction in Bur-
lington Northern—reinforced this precise reality. See Chem-
Dyne, 572 F. Supp. at 810–11 (declining at summary judgment
to determine that liability could be apportioned because the
evidence, when viewed in the light most favorable to the non-
Nos. 20-1711 & 20-1793                                          17

moving party, showed that multiple parties had contributed
to the contamination and over time much of the waste had
become commingled, making the divisibility determination
all the more complex). Our cases, too, have recognized that
joint and several liability is the norm in complex CERCLA
cases. See Metro. Water Reclamation Dist. v. N. Am. Galvanizing
& Coatings, Inc., 473 F.3d 824, 827 n.3 (7th Cir. 2007) (“The only
exception to joint liability is when the harm is divisible, but
this is a rare scenario.”); United States v. Capital Tax Corp., 545
F.3d 525, 535 (7th Cir. 2008) (“Divisibility is the exception,
however, not the rule.”).
    The apportionment inquiry proceeds in two steps. See
Burlington Northern, 556 U.S. at 614 (laying out the two-step
process); United States v. NCR Corp., 688 F.3d 833, 838 (7th Cir.
2012) (applying that process) (“2012 NCR Corp.”). The thresh-
old question is whether the harm is even capable of appor-
tionment. See Burlington Northern, 556 U.S. at 614. Making
that determination requires an initial look at the underlying
facts to determine “what type of pollution is at issue, who
contributed to that pollution, how the pollutant presents itself
in the environment after discharge, and similar questions.”
2012 NCR Corp., 688 F.3d at 838. If the preliminary review of
the facts suggests that the harm can be apportioned, the in-
quiry then must take the second step of asking with even
more factual particularity whether the evidentiary record
provides a reasonable basis for actually apportioning the lia-
bility among the PRPs. See id.
    Although the case law has described these inquiries as
proceeding in two distinct steps, it is often easier and more
practical to think of them as blending together and interre-
lated. Whether undertaken in one or two steps, the
18                                      Nos. 20-1711 & 20-1793

overarching question is whether, as a matter of record evi-
dence, the environmental harm (and responsibility for the re-
sponse costs at issue) can be apportioned by applying princi-
ples of causation.
    Whether the evidence permits the apportionment of reme-
diation liability is itself often a contested question. Some par-
ties may insist the answer is yes, while others will urge the
district court to say no. That is what happened here: Major
and Moran contended that the evidence in the summary judg-
ment record allowed the district court to make ﬁndings as to
which PRP caused what environmental harm. Von Duprin
took the opposite position, arguing that the same record evi-
dence provided no reliable basis for making the ﬁndings nec-
essary to apportion the liability. The district court’s responsi-
bility at summary judgment was to ensure that Major and Mo-
ran, as both the moving parties and the parties with the bur-
den of showing that cost-recovery liability is divisible, had
identiﬁed materially uncontested record evidence allowing
that question to be resolved in the aﬃrmative without a trial.
See Burlington Northern, 556 U.S. at 614 (explaining that the
burden for showing divisibility is on the moving party); Fed.
R. Civ. P. 56(a) (identifying the burden on the party moving
for summary judgment).
    The point of this observation is to recognize and rein-
force—as the district court did in Chem-Dyne—the complexity
and intersection of the substantive liability question with the
procedural posture at which the question is being asked. The
apportionment inquiry must be answered at summary judg-
ment in a manner consistent with both the standards (and pro-
tections) of Rule 56 and the substantive burden imposed by
§ 107(a) of CERCLA on the party requesting that cost-
Nos. 20-1711 & 20-1793                                        19

recovery liability be divided among the PRPs instead of joint
and several.
    The district court did not approach the apportionment
question this way at summary judgment. In granting Moran’s
motion for partial summary judgment on the apportionment
question, the district court determined that the harm was
“theoretically capable of apportionment” based on the opin-
ion oﬀered by Moran’s expert, Dr. Adam Love. He opined
that there were distinct sites of pollution at each property that
could be used to eﬀectively account for how much of the harm
emanated from each property. This was possible, Dr. Love ex-
plained, by examining the chemical composition of soil sam-
ples from those source sites to ascertain the concentration of
certain chemicals at each site and to compare those respective
concentrations to the chemical composition of the groundwa-
ter plume. In Moran’s view, Dr. Love’s analysis established
that the Von Duprin Property’s contributions to the total
harm were distinct from that of the other properties. This was
so, according to Dr. Love, because soil samples from the Von
Duprin Property showed a larger presence of PCE, whereas
the soil samples from the other properties—which sit upgra-
dient from Von Duprin, meaning that the groundwater ﬂows
down toward the Von Duprin Property—show a larger pres-
ence of TCE. Thus, in Dr. Love’s opinion, responsibility for
the environmental harm at issue was reasonably apportiona-
ble based on the chemical composition at the source sites vis-
à-vis the composition of the plume.
    Von Duprin disagreed, maintaining that liability should
be joint and several because the complexity of the underlying
facts showed that the harm was incapable of reliable appor-
tionment. The company supported this view by attacking Dr.
20                                      Nos. 20-1711 & 20-1793

Love’s opinion and raising larger questions about the feasibil-
ity of dividing the harm given the complexity of the underly-
ing facts. Dr. Love’s methodology, Von Duprin contended, re-
lied on soil samples collected well after large quantities of soil
had been removed from the properties and decades after re-
leases of hazardous waste. Von Duprin further oﬀered its own
expert, John McInnes, who opined that the four properties all
played a part in releasing chlorinated solvents over many dec-
ades. Von Duprin also urged that apportionment was inap-
propriate because the toxic chlorinated solvents became indis-
tinguishable once they commingled in the groundwater
plume. These observations and facts, Von Duprin advanced,
precluded a ﬁnding of divisibility at summary judgment.
    The district court reacted by seeing Von Duprin’s position
as a “concern [that] highlights a practical problem, not a the-
oretical one.” Indeed, the district court went even further, ob-
serving that Von Duprin’s concerns with the reliability of Dr.
Love’s apportionment analysis are “irrelevant to the question
of whether harm is divisible.”
    Therein lies the misstep. The district court’s approach re-
ﬂects two errors—one substantive and one procedural—that
interrelated in a way that sent the incorrect question to trial
and had the eﬀect of relieving Major of its burden of showing
that liability should be apportioned instead of imposed jointly
and severally on each PRP.
    The errors were the product of the district court approach-
ing the divisibility question at too high a level of generality,
taking too literally the use of the word “theoretically” in our
decision in 2012 NCR Corp. See 688 F.3d at 838. There we re-
stated the Burlington Northern test in terms of two steps. We
described the ﬁrst step as one at which “we must determine
Nos. 20-1711 & 20-1793                                       21

whether the harm at issue is theoretically ‘capable of appor-
tionment.’” Id. (quoting Burlington Northern, 556 U.S. at 614).
The district court overread the adverb’s importance to the
test. After all, nearly everything in theory is capable of divi-
sion if examined at a high enough level of generality. But see-
ing the question in theoretical—rather than factual and evi-
dentiary—terms robs the necessary apportionment inquiry of
any meaningful content and leads to an analysis divorced
from the Supreme Court’s instructions in Burlington Northern
and the guiding principles in the Restatement (Second) of
Torts.
    Indeed, we made much the same observation in 2012 NCR
Corp. itself. We emphasized that whether the environmental
harm at issue was capable of apportionment depended—at
the ﬁrst step of the analysis—on many ﬁndings of fact. See 688
F.3d at 838. Here, however, the district court seemed to con-
clude that the remediation liability was divisible—at least at
the theoretical level—because Moran’s expert Dr. Love of-
fered that view. But stopping with that observation eﬀectively
transformed the norm of joint and several liability in CERCLA
cost-recovery cases to divisible liability. Put another way, our
review of the summary judgment record leaves us of the view
that the district court stopped short of grappling with the
complexity inherent in a CERCLA cost-recovery case as wide-
ranging as this one. We do not read the Supreme Court’s Bur-
lington Northern decision as intending every asserted appor-
tionment defense to so easily clear the evidentiary hurdle de-
manded by the standard embodied in § 433A of the Restate-
ment.
   Consider the complexity of the environmental harm at is-
sue. At least three diﬀerent owners of four diﬀerent properties
22                                      Nos. 20-1711 & 20-1793

released hazardous waste in diﬀerent quantities and concen-
trations at diﬀerent times over several decades, at least from
the 1960s to well into the 1980s. What is more, the record does
not establish when or in what amounts any of this pollution
occurred. And, as the district court acknowledged in its
posttrial ﬁndings of fact, once the hazardous chemicals en-
tered the groundwater, commingled, and vaporized, the indi-
vidual molecules that make up the plume became indistin-
guishable. Layer this reality onto the burden a party seeking
apportionment faces and the district court’s error becomes
clear. Rather than recognizing the rarity of divisible liability
in CERCLA cases, the district court instead treated the step-
one inquiry as satisﬁed by a threshold proﬀer of expert testi-
mony by Moran that the harm could be apportioned.
    The district court’s error also manifests as a closely-related
procedural misstep. The error had the eﬀect of all but elimi-
nating Moran and Major’s burden at summary judgment un-
der the substantive law of CERCLA. Federal Rule of Civil Pro-
cedure 56 permits entry of summary judgment only “if the
movant shows that there is no genuine dispute as to any ma-
terial fact and the movant is entitled to judgment as a matter
of law.” Here that was the defendants, Moran and Major, as
the parties that sought summary judgment on the question
whether the remediation liability was divisible. Recall too
that, as a substantive matter under CERCLA, the party con-
tending that the court should abandon joint and several lia-
bility in favor of divisible liability bears the burden of proving
that a reasonable basis for apportionment exists. See Burling-
ton Northern, 556 U.S. at 614.
   The critical takeaway is to recognize that the substantive
law governing the parties’ claims (here, § 107(a) of CERCLA)
Nos. 20-1711 & 20-1793                                       23

and the procedural rule controlling whether summary judg-
ment is appropriate work in tandem. The Supreme Court un-
derscored this precise point in Anderson v. Liberty Lobby, Inc.:
“in ruling on a motion for summary judgment, the judge must
view the evidence presented through the prism of the sub-
stantive evidentiary burden.” 477 U.S. 242, 254 (1986). Stated
most succinctly, district courts, in deciding “whether a given
factual dispute requires submission to a jury[,] must be
guided by the substantive evidentiary standards that apply to
the case.” Id. at 255.
    The district court charted a diﬀerent course, one that did
not account at summary judgment for the substantive burden
Major and Moran would face at trial on the apportionment
question. The district court even seemed to require Von
Duprin to aﬃrmatively disprove that the harm was capable
of apportionment. That was error, especially at the summary
judgment stage.
    On the summary judgment record as we see it, there ap-
pears to have been a genuine dispute over material facts that
bore on the question whether the harm was capable of appor-
tionment. The district court should have viewed the trial as
the vehicle for resolving—as a deﬁnitive matter of evidence—
that question. By proceeding otherwise, the district court dis-
placed the norm of joint and several liability in favor of ap-
portionable harm, a subversion of the substantive law at odds
with CERCLA’s central design.
    The district court’s error is not one we can correct on ap-
peal. Having taken our own fresh look at the summary judg-
ment record, we see the question whether remediation liabil-
ity is capable of apportionment as both contested and diﬃ-
cult. It was hotly contested by Von Duprin and Major and
24                                     Nos. 20-1711 & 20-1793

Moran—each presented evidence bearing on the questions
underlying the apportionment inquiry. And it is diﬃcult be-
cause the overarching apportionment question that the par-
ties disagree over begets even more questions. The open ques-
tions include what role some variables—such as the length of
time between the actual discharge of the hazardous chemicals
and the chemical analysis of the soil on the properties, the re-
moval of soil on the properties as part of past remediation ef-
forts, and the commingling of the solvents once they entered
the groundwater—might play in deciding the feasibility of
determining who caused what harm with any remote conﬁ-
dence. Determining whether liability can be apportioned re-
quires wrestling with these and other questions presented by
the complexity of the underlying facts.
    Given how fact and context-speciﬁc the apportionment in-
quiry is—even at step one—we think it wiser to provide these
observations and give the district court another opportunity
to evaluate the question. In approaching this question anew,
the district court should analyze the facts and record evidence
at a higher level of particularity under the standards articu-
lated in the Restatement (Second) of Torts and the pertinent
case law.
    Do not overread our conclusions. We break no new
ground on the law of apportionment in CERCLA cases. We
merely restate the high bar for parties arguing that apportion-
ment is appropriate in a given CERCLA cost-recovery action.
The district court did not take that into account and otherwise
failed in its summary judgment ruling to support its decision
to depart from the norm of joint and several liability with fac-
tual ﬁndings rooted in the record.
Nos. 20-1711 & 20-1793                                         25

   B. Assignment of Liability After Trial
    Our reversal of the divisibility determination at summary
judgment compels us to vacate the damages award for a fresh
liability calculation as a whole. But we need to address an ad-
ditional error by the district court. After determining that ap-
portionment was appropriate, the district court proceeded to
Major and Moran’s request for contribution under § 113(f)
and allocated the liability among the parties. While we can see
the ultimate liability awards, we cannot tell how the district
court weighed the equitable factors. The error, as we see it,
resulted from the district court treating apportionment and
allocation interchangeably—so much so that we cannot be
sure how the court arrived at its determinations of liability.
    We are not quibbling with word choice. The distinction be-
tween apportioned liability and allocated liability is substan-
tive and important under CERCLA. These terms are far from
synonymous. Indeed, they refer to altogether separate statu-
tory provisions. Apportionment operates in a § 107(a) action
for the recovery of response costs, but only where the harm is
divisible. See Burlington Northern, 556 U.S. at 614. Allocated
liability, on the other hand, arises by operation of § 113(f). See
Atl. Rsch., 551 U.S. at 140. That provision authorizes PRP de-
fendants to seek contribution toward the liability from the
party seeking cost recovery in the ﬁrst instance or from other
PRP defendants. As happened here, the defendants in a
§ 107(a) cost-recovery action typically bring a counterclaim
under § 113(f) for contribution from the plaintiﬀ.
    Allocation refers to the way liability is assigned in a con-
tribution claim. See NCR Corp. v. George A. Whiting Paper Co.,
768 F.3d 682, 689 (7th Cir. 2014) (“2014 NCR Corp.”). Unlike
apportionment, which is guided by principles of causation,
26                                      Nos. 20-1711 & 20-1793

§ 113(f) of CERCLA provides that courts allocate liability
among PRPs “using such equitable factors as the court deter-
mines are appropriate.” 42 U.S.C. § 9613(f)(1). It seems easiest
to think of the allocation analysis as more ﬂexible and softer
than the apportionment analysis under § 107(a), which re-
quires more an application of principles of causation and a
form of contributory negligence. One court has described the
distinction more colorfully: “To apportion is to request sepa-
rate checks, with each party paying only for its own meal. To
allocate is to take an unitemized bill and ask everyone to pay
what is fair.” Yankee Gas Servs. Co. v. UGI Utilities, Inc., 852
F. Supp. 2d 229, 241–42 (D. Conn. 2012).
   The district court exercises substantial discretion when al-
locating liability. As Congress put it, district courts must allo-
cate response costs using “such equitable factors as the court
determines are appropriate,” 42 U.S.C. § 9613(f)(1), a level of
discretion we have described as “broad.” 2014 NCR Corp., 768
F.3d at 700. But that discretion is not without limits, and the
“court’s ultimate decision must reﬂect CERCLA’s equitable
principles.” Id. at 701. We have previously vacated a district
court’s allocation of damages where the district court did not
adequately explain its rationale for evaluating some relevant
equitable factors and not others. See id. at 702. Just as we ob-
served in 2014 NCR Corp., we must vacate the judgment
where “we cannot be sure either that the court did, or that it
did not, adequately consider all of the circumstances before
makings its decision.” Id. at 703. Just so here.
    After reaﬃrming its view that the harm was capable of ap-
portionment at summary judgment, the district court pro-
ceeded to a bench trial to conduct what it called “equitable
allocation.” To be sure, the district court mentioned equitable
Nos. 20-1711 & 20-1793                                            27

factors that it considered, including listing the Gore factors,
but the court went into no detail as to how or why it consid-
ered certain factors or discounted others. Instead, the district
court seemed to rely solely on Dr. Love’s expert testimony on
how the harm could be apportioned based on the four distinct
sources of contaminants. Without an explanation from the
district court, we cannot conduct our own evaluation of its ex-
ercise of discretion.
    In many ways, we ﬁnd ourselves stuck. We cannot discern
how the district court determined how much to award each
party and on what basis. Even more, though, our review of
the district court’s posttrial opinion leaves us of the ﬁrm con-
viction that the court merged and conﬂated its consideration
of apportionment and allocation. We do not know what por-
tions of the liability awards reﬂect apportionment and what
aspects reﬂect allocation. The Supreme Court cautioned
against this error in Atlantic Research, emphasizing that treat-
ing “contribution as if it were synonymous with apportion-
ment of expenses among PRPs” too “confuses the complimen-
tary yet distinct nature of the rights established in §§ 107(a)
and 113(f).” 551 U.S. at 138 (internal citation and quotation
omitted). The Court sounded similar caution in Burlington
Northern, emphasizing that “[e]quitable considerations play
no role in the apportionment analysis; rather, apportionment
is proper only when the evidence supports the divisibility of
the damages jointly caused by the PRPs.” 556 U.S. at 615 n.9.
   We see no path forward other than to vacate the judgment
and allow the district court to revisit the entirety of its liability
analysis. On remand and with the legal framework now clar-
iﬁed, the district court must ﬁrst revisit the apportionment
question it previously resolved at summary judgment on Von
28                                      Nos. 20-1711 & 20-1793

Duprin’s § 107(a) cost-recovery claim. Our review of the sum-
mary judgment record, as we have explained, leaves us per-
suaded that resolving the apportionment inquiry at the very
least requires consideration of the evidence presented at trial
and perhaps even additional evidence. The district court has
the discretion to fashion the remand proceedings in ways that
position the evidentiary record to allow for the ﬁndings nec-
essary to resolve the apportionment question. The court will
have the same ﬂexibility in revisiting the allocation of liability
when it resolves Major and Moran’s counterclaims under
§ 113(f).
                               IV
    Beyond the assignment of liability, the parties raise a host
of other issues on appeal. Though none is outcome determi-
native, we address them to provide as much clarity as possi-
ble for the proceedings on remand. On these remaining is-
sues, we see no errors and indeed aﬃrm each of the district
court’s challenged rulings.
     A. Major’s Bona Fide Prospective Purchaser Defense
    To encourage investment in and restoration of contami-
nated lands, Congress provided a complete defense to liabil-
ity for parties who would otherwise face liability solely by vir-
tue of acquiring and thus owning or operating on contami-
nated land. CERCLA calls this the bona ﬁde prospective pur-
chaser or BFPP defense. See 42 U.S.C. §§ 9601(40),
9607(q)(1)(C). The district court determined that Major quali-
ﬁed for the BFPP defense for two properties (the Moran Prop-
erty and the Zimmer Packaging Facility) but not for two oth-
ers (the Ertel Property and the Zimmer Paper Facility). Major
appeals the district court’s ruling on the latter two properties.
Nos. 20-1711 & 20-1793                                        29

    To qualify for the BFPP defense, PRPs must meet certain
requirements, including that—in connection with acquiring
the property in question—they make “all appropriate inquir-
ies into the previous ownership and uses of the facility in ac-
cordance with generally accepted good commercial and cus-
tomary standards and practices.” 42 U.S.C. § 9601(40).
    Zimmer Paper Facility. The district court was right to con-
clude that Major was not entitled to the BFPP defense for the
Zimmer Paper Facility. To be sure, Major did complete a
Phase 1 Environmental Assessment according to the provi-
sions of ASTM International Standard E1527-05, and, comply-
ing with that standard, did at the time satisfy parts of the “all
appropriate inquiries” requirements set forth in portions of
CERCLA’s implementing regulations. See 40 C.F.R. §§ 312.23-
312.31. But CERCLA’s regulations—in particular 40 C.F.R.
§§ 312.21 and 312.22—required more, and that more is where
Major fell short. Those provisions include requiring certain
attestations about the professional qualiﬁcations of the envi-
ronmental professionals conducting the inquiry for the pro-
spective purchase. See 40 C.F.R. § 312.21(d). These required
attestations appear nowhere in Major’s Phase 1 Environmen-
tal Assessment, however. Try as Major does to point to non-
binding agency guidance, it cannot show full compliance with
all requirements in the “all appropriate inquiries” regulation.
   Ertel Property. The district court was equally right to con-
clude that Major did not qualify for the BFPP defense for the
Ertel Property. Here, too, Major failed to make all appropriate
inquiries, though its missteps related more to timing than
substance. Major leased the Ertel Property from the City of
Indianapolis in November 2007, purchasing it outright sev-
eral years later in 2013. Major completed all appropriate
30                                     Nos. 20-1711 & 20-1793

inquiries only at the time it acquired title to the property in
2013. We agree with the district court’s conclusion that the
BFPP defense, by its terms, applies to “owner[s] and opera-
tor[s],” and Major became an operator in November 2007,
when it commenced its 99-year lease. See 42 U.S.C.
§ 9607(a)(1). Major therefore had to complete the required in-
quiries by performing or updating an environmental assess-
ment within 180 days of becoming an owner or operator. The
company failed to do so, for the only environmental assess-
ment that could satisfy the BFPP’s substantive requirements
comes from September 6, 2006—a date not within 180 days of
the commencement of the lease in November 2007.
   Moran Property. Von Duprin, in its combined reply and
cross-appeal brief, adds that the district court erred at sum-
mary judgment when it allowed Major to assert the BFPP de-
fense for the Moran Property. That position lacks merit. The
evidence presented at trial established that Major completed
the necessary inquiries in a complete and timely fashion in
connection with acquiring the Moran Property.
     B. Von Duprin’s Compliance with the National
        Contingency Plan
   We turn now to Major’s challenges to the district court’s
determinations that certain costs incurred by Von Duprin
were recoverable under § 107(a) of CERCLA.
    The parties disagree about the applicable standard of re-
view. Major invites us to review the district court’s determi-
nation of NCP compliance de novo while Von Duprin urges
application of the clear error standard. Our decision in Nu-
traSweet suggests (without expressly stating) that our review
is only for clear error. See 227 F.3d 776, 791 (7th Cir. 2000)
Nos. 20-1711 & 20-1793                                         31

(explaining that “the district court did not clearly err in con-
cluding that NutraSweet had satisﬁed the NCP”). But we do
not need to resolve the question because the district’s conclu-
sions satisfy either standard. We see no errors in the district
court’s ﬁndings that Von Duprin incurred most of the chal-
lenged costs in substantial compliance with the NCP. We
therefore reject Major’s cross-appeal on this point.
    Congress permitted the recovery of necessary response
costs incurred “consistent with” the National Contingency
Plan or NCP, a federal regulation that establishes standards
and obligations for remediation and cleanup eﬀorts. 42 U.S.C.
§ 9607(a)(4)(B); see also NutraSweet, 227 F.3d at 791. “A private
party response action will be considered ‘consistent with the
NCP’ if the action, when evaluated as a whole, is in substan-
tial compliance with the applicable requirements … and re-
sults in a CERCLA-quality cleanup.” 40 C.F.R.
§ 300.700(c)(3)(i). The requirements are numerous and task
speciﬁc. See, e.g., id. § 300.700(c)(5)–(6). The ultimate and con-
trolling inquiry is whether the expenses in question were in-
curred in “substantial compliance” with the NCP. Id.
§ 300.700(c)(3)(i). Perfect compliance is not the measuring
stick.
    When considering whether the costs Von Duprin sought
to recover were incurred consistent with the NCP, the district
court evaluated the relevant provisions of the regulations for
the speciﬁc types of costs Von Duprin sought to recover. It
concluded that Von Duprin’s remedial eﬀorts, on the whole,
reﬂected substantial compliance with the NCP. This ﬁnding,
in turn, resulted in the district court determining that Von
Duprin incurred the following costs consistent with the NCP:
$750,000 for preliminary investigation and site assessment,
32                                       Nos. 20-1711 & 20-1793

$120,000 for remediation of the public park, $465,000 for resi-
dential vapor intrusion remediation, and $365,000 for bench
and pilot testing. The only contrary ﬁnding came with respect
to the $1.5 million settlement Von Duprin paid to Threaded
Rod and about $39,000 in IDEM oversight costs. The district
court found those costs were not incurred consistent with the
NCP.
    Major contends that the district court erred in concluding
that Von Duprin’s $750,000 in investigation and site assess-
ment costs were recoverable. As best we can tell, Major seems
to take issue with the district court’s ﬁnding that these costs
relate to site assessment and other investigative work under-
taken by Von Duprin. But the position is diﬃcult to follow
and not advanced with the clarity and evidentiary support to
convince us to reverse. Going further, though, we see no legal
inﬁrmity in the district court’s observation that § 107(a) per-
mits a company to recover due diligence costs incurred in
connection with the investigation of a contaminated site. It
stands to reason, the district court sensibly explained, that
such initial inquiries are necessary to enable subsequent
measures to ensure a CERCLA-quality cleanup, as CERCLA
and the NCP both contemplate. See CNH Am., LLC v. Cham-
pion Envt’l Servs., 863 F. Supp. 2d 793, 809 (E.D. Wis. 2012) (col-
lecting district court cases within our Circuit likewise ﬁnding
that these preliminary investigative costs are recoverable un-
der CERCLA).
   Nor are we convinced by Major’s insistence that the chal-
lenged costs are not recoverable because they are not ex-
pressly recognized in the NCP. It would be one thing if Von
Duprin incurred costs proscribed by the NCP, as such costs
would not be recoverable under the plain terms of § 107(a).
Nos. 20-1711 & 20-1793                                      33

But we see nothing inconsistent—lacking substantial compli-
ance—with the NCP to permit Von Duprin to recover due dil-
igence site-assessment costs. It seems diﬃcult to call such
costs inconsistent with the NCP, to say nothing of CERCLA’s
broader objectives.
   On this record, and especially against Major’s undevel-
oped argument on appeal, we cannot conclude that the pre-
liminary assessment and investigative costs—those not ex-
pressly addressed by the NCP—were not incurred consistent
with the NCP. We therefore see no error in the district court’s
ﬁnding that the $750,000 Von Duprin spent on preliminary
investigative measures and site-assessment was recoverable
under § 107(a).
    Major also challenges Von Duprin’s recovery of certain
other costs. These costs included the remediation of the public
park, residential vapor intrusion remediation, and various
tests. The district court took considerable care reviewing the
testimony oﬀered by Major and Von Duprin on these costs
against the backdrop of the pertinent NCP regulations. While
noting that Von Duprin’s compliance was not perfect, the dis-
trict court concluded these challenged costs were incurred in
substantial compliance with the NCP.
    We agree. Von Duprin substantially complied with the rel-
evant components of the NCP dealing with documentation,
health and safety protocols, site investigation, and public in-
put for that set of challenged costs. And throughout the eﬀort,
the company worked with IDEM. See NutraSweet, 227 F.3d at
791 (citing with favor the cooperation with regulatory agen-
cies in discussing compliance with the NCP). To be sure, the
district court correctly observed that Von Duprin failed to
comply to the letter with certain NCP prescriptions. But to
34                                      Nos. 20-1711 & 20-1793

reverse the district court on this front would require a level of
perfection at odds with Congress’s more limited requirement
that recoverable costs only be incurred in “substantial com-
pliance” with the NCP.
     C. District Court’s Admission of Dr. Adam Love’s
        Expert Testimony
    We come in closing to Von Duprin’s challenge to the dis-
trict court’s denial of its motion to exclude the testimony of
Dr. Adam Love, Moran’s expert who oﬀered opinions perti-
nent to the apportionment of liability under § 107(a) of
CERCLA.
    “We review de novo whether a district court properly fol-
lowed the framework for determining the admissibility of ex-
pert testimony.” Schultz v. Akzo Nobel Paints, LLC, 721 F.3d 426,
430–31 (7th Cir. 2013); see also Fed. R. Evid. 702; Daubert v.
Merrell Dow Pharm., Inc., 509 U.S. 579 (1993). If it did, “we re-
view its decision to admit or exclude expert testimony only
for an abuse of discretion.” Schultz, 721 F.3d at 431.
    In Daubert, the Supreme Court explained that Federal Rule
of Evidence 702 imposes a gatekeeping responsibility on dis-
trict courts to ensure that any proposed expert testimony “is
not only relevant, but reliable.” 509 U.S. at 589. We aﬀord dis-
trict courts substantial latitude in making the ﬁndings neces-
sary to fulﬁll this gatekeeping role. See Jenkins v. Bartlett, 487
F.3d 482, 489 (7th Cir. 2007). Latitude is not a blank check,
however, and the court must provide more than just conclu-
sory statements of admissibility to show that it adequately
performed its gatekeeping function. See Naeem v. McKesson
Drug Co., 444 F.3d 593, 608 (7th Cir. 2006).
Nos. 20-1711 & 20-1793                                      35

     We start with two points of agreement among all parties.
First, Dr. Love oﬀered a relevant opinion. Indeed, he opined
on whether and the extent to which each property contributed
to the commingled plume—the question at the epicenter of
whether liability could be apportioned. To our mind, it would
be diﬃcult to identify a question more relevant to the entire
litigation. Second, nobody questions Dr. Love’s qualiﬁcations,
as he plainly has the training and experience necessary to of-
fer an opinion pertinent to whether responsibility for the con-
tamination can be divided among the PRPs.
    What the parties tangled over was whether Dr. Love
reached his opinions by applying a methodology that inhered
with suﬃcient reliability to satisfy the requirements of Rule
702. He came to his opinions by relying on soil and ground-
water data collected during site investigations that occurred
primarily from 2005 to 2017. Using this data, he analyzed soil
samples at each property and then compared that to the
chemical makeup of the groundwater plume. Dr. Love
claimed that the distinct chemical compounds in the contam-
inated soil he tested at each site provided a way to apportion
each property’s contributions to the total environmental harm
that is the commingled groundwater plume. At no point did
Dr. Love opine on which party was responsible for what
amount of the harm. Instead, he oﬀered a view on the propor-
tion of the total contamination that was attributable to each
property.
    Von Duprin insists that the district court should have ex-
cluded Dr. Love’s opinions because his underlying analysis
failed to account for a range of confounding variables that
prevented him from making reliable ﬁndings. While Von
Duprin advances some sound observations about the
36                                         Nos. 20-1711 & 20-1793

limitations of Dr. Love’s ultimate opinions, we cannot say the
district court abused its discretion in admitting the opinions
in the ﬁrst instance. Right to it, Von Duprin’s challenge goes
more to the weight (or lack thereof) the district court should
have aﬀorded Dr. Love’s ultimate opinions. See Burton v. E.I.
du Pont de Nemours and Co., Inc., 994 F.3d 791, 826 (7th Cir.
2021) (“Although Rule 702 places the judge in the role of gate-
keeper for expert testimony, the key to the gate is not the ul-
timate correctness of the expert’s conclusion but rather the
soundness and care with which the expert arrived at her opin-
ion.”) (cleaned up). Cross-examination, the presentation of
contrary evidence, and an instruction on the burden of proof
are the appropriate methods through which Von Duprin
could have attacked Dr. Love’s opinions. See Schultz, 721 F.3d
at 431.
    Be careful not to confuse what we are saying here. To con-
clude, as we have, that the district court did not abuse its dis-
cretion in admitting and considering Dr. Love’s opinions is
not to say that those same opinions were suﬃcient as an evi-
dentiary matter to establish the divisibility of cost-recovery li-
ability under § 107(a) of CERCLA. Admissibility and eviden-
tiary suﬃciency are not one and the same.
                         *      *      *
    This is a diﬃcult case involving many decades, many par-
ties, and many millions of dollars. We see no merit to much of
the challenges to the district court’s rulings. But we do agree
with Von Duprin that the district court’s summary judgment
determination on apportionment requires remand. And we
agree with Major that the district court’s ultimate allocation
of liability necessitates a remand as well. For these reasons,
we AFFIRM in part and VACATE and REMAND in part.