                     FOR PUBLICATION

    UNITED STATES COURT OF APPEALS
         FOR THE NINTH CIRCUIT


 ASARCO, LLC,                                      No. 13-35356
                      Plaintiff-Appellant,
                                                     D.C. No.
                      v.                          2:12-cv-00283-
                                                       EJL
 UNION PACIFIC RAILROAD
 COMPANY, a Utah corporation;
 UNION PACIFIC CORPORATION,                           OPINION
              Defendants-Appellees,


         Appeal from the United States District Court
                   for the District of Idaho
          Edward J. Lodge, District Judge, Presiding

                     Argued and Submitted
              July 10, 2014—Seattle, Washington

                      Filed August 27, 2014

Before: A. Wallace Tashima and Mary H. Murguia, Circuit
     Judges, and Cormac J. Carney, District Judge.*

                    Opinion by Judge Carney




 *
   The Honorable Cormac J. Carney, United States District Judge for the
Central District of California, sitting by designation.
2                  ASARCO V. UNION PACIFIC

                           SUMMARY**


                       Environmental Law

    The panel reversed the dismissal of a mining company’s
action under § 113(f) of the Comprehensive Environmental
Response, Compensation, and Liability Act, seeking a share
of cleanup costs paid for environmental harm at the Coeur
d’Alene Superfund Site.

     The panel held that the mining company’s claim was not
barred by CERCLA’s three-year statute of limitations for
claims seeking contribution after entry of a judicially
approved settlement. The panel held that even though the
first amended complaint included allegations that were
expressly disclaimed in the original complaint, it related back
to the date of the original complaint under Fed. R. Civ. P.
15(c)(1)(B) because it arose out of the same conduct,
transaction, or occurrence as that set forth in the original
complaint. The panel held that the original complaint was
timely because Rule 6(a)’s general rule for counting time,
excluding the day of the event that triggered the period,
applied.

    The panel held that the mining company’s claim was not
unambiguously barred by a prior agreement that settled the
defendant’s claims against the mining company at the same
site. The panel concluded that a “mutual release” provision
in the parties’ settlement agreement did not unambiguously
release the claim in this case.

  **
     This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
                ASARCO V. UNION PACIFIC                     3

                        COUNSEL

Gregory Evans (argued) and Laura G. Brys, Integer Law
Corporation, Los Angeles, California; Linda R. Larson,
Russell C. Prugh, and Meline G. MacCurdy, Marten Law
PLLC, Seattle, Washington, for Plaintiff-Appellant.

Carolyn McIntosh (argued) and Maxine Martin, Patton Boggs
LLP, Denver, Colorado; Ausey H. Robnett III, Paine
Hamblen LLP, Coeur d’Alene, Idaho; Gail L. Wurtzler, Davis
Graham & Stubbs LLP, Denver, Colorado, for Defendants-
Appellees.


                         OPINION

CARNEY, District Judge:

    ASARCO, LLC (“Asarco”) appeals the district court’s
dismissal of its contribution action brought under § 113(f) of
the Comprehensive Environmental Response, Compensation,
and Liability Act (“CERCLA”), 42 U.S.C. §§ 9601–9675.
Asarco seeks to recover from Union Pacific Railroad Co. and
Union Pacific Corp. (together, “Union Pacific”) a share of
$482 million in cleanup costs Asarco paid for environmental
harm at the Coeur d’Alene Superfund Site in Northern Idaho.
The district court dismissed the action under Federal Rule of
Civil Procedure 12(b)(6), concluding that although Asarco’s
claim was timely, it was barred by a 2008 settlement
agreement between the parties that settled Union Pacific’s
claims against Asarco at the same site. We conclude that
Asarco’s claim was timely, but that the parties’ 2008
settlement agreement did not unambiguously release Asarco’s
4               ASARCO V. UNION PACIFIC

claim here. We therefore reverse the district court’s
judgment dismissing the case under Rule 12(b)(6).

                       BACKGROUND

    Asarco and Union Pacific both participated in nearly a
century of mining operations in the Coeur d’Alene River
watershed, a 1,500-square-mile area located in Idaho’s
northern panhandle. Asarco operated over 20 mines in the
Coeur d’Alene site, and Union Pacific built rail lines and
transported ore and other materials for the region’s mining
and smelting facilities. In 1983, the Environmental
Protection Agency (“EPA”) listed the Coeur d’Alene site on
the CERCLA National Priorities List. Since then the site has
undergone over 30 years of cleanup efforts by the EPA, the
State of Idaho, and potentially responsible parties, including
Asarco and Union Pacific.

    In the 1990s, the United States, the State of Idaho, and the
Coeur d’Alene Tribe each filed various claims against Asarco
and other mining companies for response costs and natural
resource damages at the Coeur d’Alene site. These actions
were consolidated in 2003 and, after a 78-day trial, Judge
Lodge of the United States District Court for the District of
Idaho issued an order apportioning liability based on the
volume of mining waste released into the basin’s waterways.
Asarco was found at least 22 percent responsible. Coeur
d’Alene Tribe v. Asarco, Inc., 280 F. Supp. 2d 1094, 1121 (D.
Idaho 2003).

    In 2005, before the damages portion of the consolidated
case was concluded, Asarco filed for bankruptcy protection
under Chapter 11 of the United States Bankruptcy Code.
Through bankruptcy, Asarco sought to resolve approximately
                ASARCO V. UNION PACIFIC                       5

$6.5 billion in environmental liabilities at 53 sites throughout
the country. Union Pacific and the United States both filed
proofs of claim.

    Union Pacific’s proofs of claim sought a general
unsecured claim for payment of freight charges and response
costs at numerous sites, including $52 million in CERCLA
response costs Union Pacific had paid at the Coeur d’Alene
site. In 2008, the parties entered into a settlement agreement
(the “UP Settlement”), which resolved “all the claims by UP
or claims which UP could have filed against ASARCO,” and
allowed Union Pacific a general unsecured claim of about $4
million. Upon the parties’ joint motion, the bankruptcy court
approved the settlement.

   The UP Settlement contains a “mutual release” provision,
which states in relevant part:

       ASARCO agrees . . . to hereby release,
       remise, and discharge UP . . . from any and all
       damages, losses, expenses, costs, liabilities,
       claims, demands, suits, causes of action, and
       complaints, of any kind, character or
       description, in law or in equity, whether
       known or unknown, arising out of or in any
       way connected with . . . Remaining Sites
       Costs. (Emphasis added.)

The UP Settlement defines “Remaining Sites Costs” to mean
“costs of response under CERCLA incurred by UP at the
Remaining Sites,” including the Coeur d’Alene site.
(Emphasis added.)
6               ASARCO V. UNION PACIFIC

    The United States also filed proofs of claim in Asarco’s
bankruptcy case, asserting that Asarco was jointly and
severally liable for more than $2 billion in cleanup costs at
the Coeur d’Alene site. The bankruptcy court held a hearing
to estimate the United States’ claims against Asarco, but
before the court ruled, Asarco and the United States executed
an agreement settling the United States’ Coeur d’Alene
claims (“US CDA Settlement”).

    The US CDA Settlement resolved Asarco’s liability for
all remaining response costs and natural resource damages
associated with the Coeur d’Alene site. Under the settlement,
Asarco agreed that the United States would be entitled to
general unsecured claims totaling about $482 million. For its
part, the United States covenanted not to sue Asarco for
further CERCLA costs “[w]ith respect to the Coeur d’Alene
Site.” The bankruptcy court approved the proposed
settlement on June 5, 2009.

    On June 5, 2012, Asarco filed the underlying contribution
action, seeking to recoup from Union Pacific a share of the
$482 million it paid under the US CDA Settlement. Asarco
alleged that it had paid more than its allocable share of costs
at the Coeur d’Alene site and demanded that Union Pacific
pay “its equitable share of any overpayment of costs by
Asarco.” Asarco’s original complaint defined the Coeur
d’Alene site as “a 1,500-square mile area located in northern
Idaho and eastern Washington,” including “a 21-square mile
area around [the Bunker Hill mining] complex” and the upper
and lower basins of the Coeur d’Alene River. The original
complaint provided that “[f]or purposes of this action, the
Coeur d’Alene Basin . . . excludes the drainage of the North
Fork of the Coeur d’Alene River.” Less than two months
later, however, Asarco filed a First Amended Complaint
                ASARCO V. UNION PACIFIC                      7

(“FAC”) as of right under Rule 15(a)(1), and amended the
definition of “Coeur d’Alene Basin” to include the North
Fork drainage area that was originally excluded.

    Union Pacific filed a motion to dismiss Asarco’s FAC
under Rule 12(b)(6), arguing that Asarco’s claim was barred
by the statute of limitations, the UP Settlement, res judicata,
judicial estoppel, Union Pacific’s contribution protection, and
Asarco’s lack of any contribution rights. The district court
rejected Union Pacific’s statute of limitations arguments, but
nevertheless granted the motion because it concluded that the
action was barred by the UP Settlement’s release provisions.

    The district court acknowledged Asarco’s argument that
the defined term “Remaining Sites Costs” limited Asarco’s
release to claims for costs “incurred by UP,” but reasoned
that if it read the agreement as “limiting the releases to only
Union Pacific’s claims” the releases would then “be anything
but mutual.” ASARCO, LLC v. Union Pac. R.R., 936 F. Supp.
2d 1197, 1204 (D. Idaho 2013). The district court concluded
that “[g]iven the scope of the definitions used in the FAC and
the plain language of the [UP] Settlement, it is clear that the
claim raised in the FAC is precluded by the mutual release
language of the [UP] Settlement.” Id. at 1204–05. The
district court therefore dismissed Asarco’s action and
declined to rule on Union Pacific’s remaining defenses. Id.
at 1206.

                  STANDARD OF REVIEW

    We review de novo the district court’s dismissal for
failure to state a claim under Rule 12(b)(6). Hartmann v. Cal.
Dep’t of Corr. & Rehab., 707 F.3d 1114, 1121 (9th Cir.
2013). We may affirm the district court’s dismissal on any
8                ASARCO V. UNION PACIFIC

ground supported by the record. Id. (citing Tahoe-Sierra
Pres. Council, Inc. v. Tahoe Reg’l Planning Agency, 322 F.3d
1064, 1076!77 (9th Cir. 2003)).

    Dismissal under Rule 12(b)(6) on the basis of an
affirmative defense is proper only if the defendant shows
some obvious bar to securing relief on the face of the
complaint. See Sams v. Yahoo! Inc., 713 F.3d 1175, 1179
(9th Cir. 2013) (“[T]he assertion of an affirmative defense
may be considered properly on a motion to dismiss where the
‘allegations in the complaint suffice to establish’ the
defense.” (quoting Jones v. Bock, 549 U.S. 199, 215 (2007)));
5B Charles Alan Wright et al., Federal Practice and
Procedure § 1357 (3d ed. 1998) (“[A] dismissal under Rule
12(b)(6) is likely to be granted by the district court only in the
relatively unusual case in which the plaintiff includes
allegations that show on the face of the complaint that there
is some insuperable bar to securing relief . . . .”). If, from the
allegations of the complaint as well as any judicially
noticeable materials, an asserted defense raises disputed
issues of fact, dismissal under Rule 12(b)(6) is improper.
Scott v. Kuhlmann, 746 F.2d 1377, 1378 (9th Cir. 1984) (per
curiam).

                           ANALYSIS

                                I

    We first consider whether Asarco’s FAC is barred by
CERCLA’s three-year statute of limitations for claims
seeking contribution after entry of a judicially approved
settlement. See 42 U.S.C. § 9613(g)(3). Union Pacific
contends that Asarco’s FAC was untimely because (1) it did
not relate back to the date of the original complaint under
                 ASARCO V. UNION PACIFIC                       9

Rule 15(c)(1)(B), and (2) even if it did, the original complaint
was filed one day too late. We review de novo both the
question whether an amended pleading relates back under
Rule 15(c)(1)(B), Martell v. Trilogy Ltd., 872 F.2d 322, 325
(9th Cir. 1989), and the question whether a claim is barred by
the statute of limitations, Orr v. Bank of Am., NT & SA,
285 F.3d 764, 779 (9th Cir. 2002).

                               A

    An otherwise time-barred claim in an amended pleading
is deemed timely if it relates back to the date of a timely
original pleading. Under Rule 15(c)(1)(B), an amendment
asserting a new or changed claim relates back to the date of
the original pleading if the amendment “arose out of the
conduct, transaction, or occurrence set out . . . in the original
pleading.” An amended claim arises out of the same conduct,
transaction, or occurrence if it “will likely be proved by the
‘same kind of evidence’ offered in support of the original
pleading.” Percy v. S.F. Gen. Hosp., 841 F.2d 975, 978 (9th
Cir. 1988) (quoting Rural Fire Prot. Co. v. Hepp, 366 F.2d
355, 362 (9th Cir. 1966)). To relate back, “the original and
amended pleadings [must] share a common core of operative
facts so that the adverse party has fair notice of the
transaction, occurrence, or conduct called into question.”
Martell, 872 F.2d at 325. The relation back doctrine of Rule
15(c) is “liberally applied.” Clipper Exxpress v. Rocky
Mountain Motor Tariff Bureau, Inc., 690 F.2d 1240, 1259
n.29 (9th Cir. 1982).

                               1

    This case presents an issue of first impression in this
Circuit: Can an amended pleading relate back if it includes
10              ASARCO V. UNION PACIFIC

allegations that were expressly disclaimed in the original
pleading? We hold that it can, and that in such cases the test
continues to be the Rule 15(c)(1)(B) standard itself —
whether the amended claim arises out of the same conduct,
transaction, or occurrence as that set forth in the original
complaint.

     In so holding, we are mindful of two competing concerns.
On the one hand, the relation back doctrine is to be liberally
applied. See id.; see also Rural Fire, 366 F.2d at 362 (noting
that Rule 15(c) “is liberally applied especially if no
disadvantage will accrue to the opposing party”). Indeed,
Rule 15’s purpose “is to provide maximum opportunity for
each claim to be decided on its merits rather than on
procedural technicalities.” 6 Wright et al., supra, § 1471.
Gone are the code pleading days when a party was
“irrevocably bound to the legal or factual theory of the party’s
first pleading.” Id.

    On the other hand, the purpose of the statute of limitations
— protecting defendants from stale claims — is also to be
respected. See Credit Suisse Sec. (USA) LLC v. Simmonds,
132 S. Ct. 1414, 1420 (2012); see also FDIC v. Conner,
20 F.3d 1376, 1385 (5th Cir. 1994). Amendments that
significantly alter the pleadings could require the opposing
party to start over and prepare the case a second time. 6A
Wright et al., supra, § 1497. Consistent with the protective
purpose of the statute of limitations, “[f]airness to the
defendant demands that the defendant be able to anticipate
claims that might follow from the facts alleged by the
plaintiff.” Percy, 841 F.2d at 979.

   Rule 15(c) strikes a balance between these competing
concerns by providing that once litigation has been
                 ASARCO V. UNION PACIFIC                      11

commenced, an opposing party is on notice that the pleading
party may subsequently raise any claims or defenses that
form part of the same conduct, transaction, or occurrence as
the original pleading. Thus, we have said, “[i]t is the
‘conduct, transaction, or occurrence’ test of Rule 15(c) which
assures that the relation back doctrine does not deprive the
defendant of the protections of the statute of limitations.”
Santana v. Holiday Inns, Inc., 686 F.2d 736, 739 (9th Cir.
1982); see also Conner, 20 F.3d at 1386 (“In the end . . . , the
best touchstone for determining when an amended pleading
relates back to the original pleading is the language of Rule
15(c) . . . .”); 6A Wright et al., supra, § 1497 (explaining that
even where “[a]mendments . . . go beyond the mere
correction or factual modification of the original pleading and
significantly alter the claim or defense alleged in that
pleading[,] . . . the search under Rule 15(c) is for a common
core of operative facts in the two pleadings”).

    Our decision in Rural Fire Protection Co. v. Hepp is
instructive. There, the plaintiffs’ timely original complaint
claimed unpaid wages under the Fair Labor Standards Act for
pay periods between September 5, 1959, and April 30, 1960.
366 F.2d at 361. During trial, and after the statutory
limitations period had expired, plaintiffs were granted leave
to amend their complaint to claim wages for an additional pay
period from April 30 to May 19, 1960. Id. Ruling on the
defendants’ statute of limitations argument, we reasoned that
“there [could] be no question but that the amended pleading
was based on the same transaction, was to be proved by the
same kind of evidence (appellant’s time records), and did not
take appellant by surprise.” Id. at 362. The amendment,
therefore, related back. Id.
12               ASARCO V. UNION PACIFIC

    We do not believe it would have made any difference had
the original complaint in Rural Fire explicitly excluded
wages for the April 30 to May 19, 1960 pay period. The
plaintiffs there could have conceivably done so because, for
example, they incorrectly believed they had no colorable
claim to wages for that pay period and thus determined in
good faith to limit the scope of their original claim. But
suppose they were to learn later while conducting discovery
that they in fact did have a colorable basis to seek wages for
that period — would they then be confined to the boundaries
of their precise pre-discovery claim?

     We think not, for such a rule would clearly be
inconsistent with the limited role Rule 15(c) assigns to the
initial pleading. Under Rule 15(c)’s liberal standard, a
plaintiff need only plead the general conduct, transaction, or
occurrence to preserve its claims against a defendant. The
exact contours of those claims — the facts that will ultimately
be alleged and the final scope of relief that will be sought —
can and should be sorted out through later discovery and
amendments to the pleadings. See 6 Wright et al., supra,
§ 1471 (“[Initial pleadings] no longer carry the burden of fact
revelation and issue formulation, which now is discharged by
the discovery process.”). We see no reason to disturb the
limited role assigned to initial pleadings under Rule 15 where
a party in good faith initially disclaims certain facts or relief.
Parties should not be discouraged from limiting their initial
pleadings to claims and defenses that have evidentiary
support. Nor should they fear that doing so will foreclose
them from amending their pleadings if new facts come to
light after further investigation and discovery.

    Of course, Union Pacific is correct that notice is an
essential element in the relation back determination. But
                ASARCO V. UNION PACIFIC                     13

Rule 15 does not require that a pleading give notice of the
exact scope of relief sought. Rather, it must give “fair notice
of the transaction, occurrence, or conduct called into
question.” Martell, 872 F.2d at 325. So long as a party is
notified of litigation concerning a particular transaction or
occurrence, that party has been given all the notice that Rule
15(c) requires. When a defendant is so notified, “the
defendant knows that the whole transaction described in it
will be fully sifted, by amendment if need be, and that the
form of the action or the relief prayed or the law relied on
will not be confined to their first statement.” Id. at 326
(quoting Barthel v. Stamm, 145 F.2d 487, 491 (5th Cir.
1944)).

    Accordingly, we hold that even where an amendment
trenches on factual ground that the original pleading said
would be off limits, the standard is the same. In such cases,
the standard to be applied is Rule 15(c)’s liberal “conduct,
transaction, or occurrence” test.

                              2

    Applying the Rule 15(c)(1)(B) standard here, we agree
with the district court that Asarco’s FAC relates back to the
date of its original complaint. The key change in Asarco’s
FAC was its inclusion of a geographical area within the
Coeur d’Alene basin — the drainage of the North Fork of the
Coeur d’Alene River — that was explicitly excluded in its
original complaint. Asarco’s original complaint asserted that

       [f]or purposes of this action, the Coeur
       d’Alene Basin refers to the watershed of the
       South Fork of the Coeur d’Alene River, the
       main stem of the Coeur d’Alene River and its
14                ASARCO V. UNION PACIFIC

         floodplain, including the lateral lakes and
         associated wetlands, and Lake Coeur d’Alene,
         but excludes the drainage of the North Fork of
         the Coeur d’Alene River. (Emphasis added.)

Less than two months later, Asarco filed its FAC, which
redefined the “Coeur d’Alene Basin” to encompass “the
watersheds of the North Fork and the South Fork of the
Coeur d’Alene River, the main stem of the Coeur d’Alene
River and its floodplain, including the lateral lakes and
associated wetlands, and Lake Coeur d’Alene.” (Emphasis
added.)

    Notwithstanding that change, we conclude that Asarco’s
original complaint clearly put Union Pacific on notice of the
conduct, transaction, or occurrence set forth in the FAC.
Both pleadings concern Asarco’s and Union Pacific’s
historical activities at the “Coeur d’Alene Site” — “a 1,500-
square mile area located in northern Idaho and eastern
Washington.”1 Both pleadings seek contribution based on the
same consent decree, which resolved Asarco’s liability for
CERCLA response costs in the entire Coeur d’Alene basin.
And, in order to determine the scope of Union Pacific’s
contribution protection, both pleadings would inevitably
require an assessment of Union Pacific’s consent decrees
settling claims for cleanup costs in the Coeur d’Alene basin.
These factual overlaps are more than enough. Asarco’s FAC
will doubtless “be proved by the ‘same kind of evidence’”
that would have been offered in support of its original



 1
   As the district court observed, “the Coeur d’Alene Basin geographical
area is large and encompasses both the North and South Forks of the
Coeur d’Alene River.”
                 ASARCO V. UNION PACIFIC                      15

complaint. Percy, 841 F.2d at 978 (quoting Rural Fire,
366 F.2d at 362).

    Liberally applying Rule 15(c), we conclude, as did the
district court, that Asarco’s FAC relates back to the date of its
original complaint.

                               B

    Of course, relation back does not help Asarco if the
original complaint was not timely in the first instance.
CERCLA § 113(g)(3) provides that “[n]o action for
contribution for any response costs or damages may be
commenced more than 3 years after . . . the date of . . . entry
of a judicially approved settlement with respect to such costs
or damages.” 42 U.S.C. § 9613(g)(3)(B). Because Asarco
filed its original complaint on June 5, 2012 — on precisely
the third anniversary of the date the US CDA Settlement was
entered by the bankruptcy court — the timeliness of Asarco’s
complaint depends on whether Federal Rule of Procedure
6(a)’s general rule for counting time applies.

     Under Rule 6(a), the day of the event that triggers the
period is excluded for purposes of computing the period’s end
date. See Fed. R. Civ. P. 6(a)(1). This is known as the
anniversary method. If the anniversary method is applied, the
first day of the period would be June 6, 2009 (the day after
the US CDA Settlement was entered), and the last day for
filing would be June 5, 2012. Under an alternative method,
known as the calendar-date method, the day of the event that
triggers the period is counted as the first day. If the calendar-
date method is applied, the first day of the period would be
June 5, 2009, and the last day for filing would be June 4,
2012. Asarco’s original complaint would thus be timely
16               ASARCO V. UNION PACIFIC

under Rule 6(a)’s anniversary method, but not under the
calendar-date method.

    Rule 6(a)’s method applies by default to “any statute that
does not specify a method of computing time.” Fed. R. Civ.
P. 6(a); see also Patterson v. Stewart, 251 F.3d 1243, 1246
(9th Cir. 2001) (“Rule 6(a) is widely applied to federal
limitations periods” and “can apply to ‘any applicable statute’
in the absence of contrary policy expressed in the statute.”
(quoting Union Nat’l Bank v. Lamb, 337 U.S. 38, 40–41
(1949))). Here, CERCLA § 113(g)(3) says nothing about the
method of counting to be applied, nor does it manifest any
intent to deviate from Rule 6(a)’s method.

    Union Pacific argues that CERCLA § 113(g)(3) specifies
a method of computing time because it directs that the
limitations period begins to run on “the date of . . . entry of a
judicially approved settlement.” Appellee’s Br. at 35
(emphasis added). But that simply shows that § 113(g)(3)
specifies the day of the triggering event. It does “not specify
a method of computing time.” Fed. R. Civ. P. 6(a). Indeed,
Rule 6(a)(1) implicitly recognizes that the “day of the event
that triggers the period” and the first day of the period for
computation purposes do not have to be the same day. Fed.
R. Civ. P. 6(a)(1)(A); see United States v. Inn Foods, Inc.,
383 F.3d 1319, 1325 (Fed. Cir. 2004) (“[S]tatutes of
limitations . . . often identify the date on which a time period
starts, but not the date on which the period ends.”).

    Moreover, Union Pacific’s reliance on § 113(g)(3)’s
language runs contrary to our precedent. In Patterson v.
Stewart, we applied Rule 6(a)’s method to nearly identical
language in the Antiterrorism and Effective Death Penalty
Act’s (“AEDPA”) limitations provision, 28 U.S.C.
                ASARCO V. UNION PACIFIC                    17

§ 2244(d)(1). See 251 F.3d at 1245–46. Just as CERCLA
§ 113(g)(3) directs that the period runs from the date the
judicially approved settlement is entered, AEDPA directs that

       [t]he limitation period shall run from the
       latest of . . . the date on which the judgment
       became final . . . [,] the date on which the
       impediment to filing an application . . . is
       removed, . . . the date on which the
       constitutional right asserted was initially
       recognized by the Supreme Court, . . . or . . .
       the date on which the factual predicate of the
       claim . . . could have been discovered.

28 U.S.C. § 2244(d)(1) (emphasis added).                Yet
notwithstanding AEDPA’s clear language that the period runs
from the date of a triggering event, we concluded in
Patterson that “AEDPA does not provide an alternative
method for computing time periods.” 251 F.3d at 1246. We
reach the same conclusion as to CERCLA § 113(g)(3).

    Union Pacific points to nothing in CERCLA’s language
or legislative history that suggests that Congress intended to
deviate from Rule 6(a)’s method of calculation. See id.; see
also Inn Foods, 383 F.3d at 1325 (“[C]ourts have chosen to
follow the guidance of Rule 6(a) absent clear language to the
contrary in the statute . . . .”). Accordingly, we apply Rule
6(a)’s anniversary method and conclude that Asarco’s
original complaint, as well as its FAC, was timely under
CERCLA § 113(g)(3).
18                  ASARCO V. UNION PACIFIC

                                     II

    Having determined that Asarco’s FAC was timely, we
now consider whether it is barred by the UP Settlement’s
“mutual release” provision. The meaning of a settlement
agreement is, as with all contracts, a question of law subject
to de novo review. City of Emeryville v. Robinson, 621 F.3d
1251, 1261 (9th Cir. 2010).

    The parties’ key dispute is whether the UP Settlement
unambiguously releases Asarco’s claim here against Union
Pacific.2 If the settlement agreement is ambiguous, then
interpretation of the agreement presents a fact issue that
cannot be resolved on a motion to dismiss. See State Farm
Mut. Auto. Ins. Co. v. Fernandez, 767 F.2d 1299, 1301 (9th
Cir. 1985) (“The interpretation of a contract presents a mixed
question of law and fact. The existence of an ambiguity must
be determined as a matter of law. If an ambiguity exists, a
question of fact is presented.” (citations omitted)); see also
Scott, 746 F.2d at 1378 (affirmative defenses may not be
asserted by motion to dismiss if they raise disputed issues of
fact); 11 Richard A. Lord, Williston on Contracts
[“Williston”] § 33:42 (4th ed. 2014) (“[T]here is unanimity”
that evidence of the surrounding circumstances is necessary
“when an ambiguity . . . exist[s].”).

    We conclude that the UP Settlement is ambiguous. The
agreement’s “mutual release” provision states, in relevant
part:


 2
   Because the settlement agreement was filed with the bankruptcy court
and is a publicly available record, it is properly subject to judicial notice,
see In re E.R. Fegert, Inc., 887 F.2d 955, 957–58 (9th Cir. 1989), and thus
may be considered on a Rule 12(b)(6) motion to dismiss.
                ASARCO V. UNION PACIFIC                     19

       ASARCO agrees . . . to hereby release,
       remise, and discharge UP . . . from any and all
       damages, losses, expenses, costs, liabilities,
       claims, demands, suits, causes of action, and
       complaints, of any kind, character or
       description, in law or in equity, whether
       known or unknown, arising out of or in any
       way connected with . . . Remaining Sites
       Costs. (Emphasis added.)

Significantly, “Remaining Sites Costs” are separately defined
in the agreement as “costs of response under CERCLA
incurred by UP at the Remaining Sites,” (emphasis added),
and “Remaining Sites” are in turn defined to include the
Coeur d’Alene site. Read together with these definitions, the
“mutual release” provision releases all claims held by Asarco
that arise out of or are in any way connected with Coeur
d’Alene response costs incurred by Union Pacific. The
agreement does not explicitly release Coeur d’Alene response
costs incurred by Asarco.

     Generally, “language will be deemed ambiguous when it
is reasonably susceptible to more than one interpretation.” 11
Williston § 32:2. Here, the release provision could plausibly
mean, as Union Pacific reads it, that Asarco’s contribution
claim against Union Pacific is released because the claim is
broadly related to CERCLA response costs incurred by Union
Pacific. But this is not the only reasonable interpretation.
The release provision could also plausibly mean that Asarco’s
contribution claim against Union Pacific is reserved, not
released, because the claim only relates to response costs
incurred by Asarco. After all, the limitation to costs incurred
by Union Pacific could have easily been replaced with
“incurred by UP or Asarco,” had that been the parties’ intent.
20              ASARCO V. UNION PACIFIC

Because both parties’ interpretations are reasonable, the
mutual release provision is ambiguous.

      Asarco’s interpretation is supported by the agreement’s
repeated references to the release of Union Pacific’s claims.
The agreement states that it is “intended to serve as a
comprehensive settlement of all the claims by UP or claims
which UP could have filed against ASARCO with respect to
. . . Remaining Sites Costs,” (emphasis added), and that “the
mutual releases set forth in Section [V] apply to all claims UP
may have filed, or had a right to file, in the ASARCO Chapter
11 case” and not to “any matters other than those expressly
specified therein.” It also notes that it is an agreement “[i]n
settlement and satisfaction of all claims and causes of action
of UP . . . .” (Emphasis added.)

    Union Pacific’s interpretation, by contrast, is inconsistent
with these references and renders superfluous the phrase
“incurred by UP” in the definition of Remaining Sites Costs.
See 11 Williston § 32:5 (“[E]very word, phrase or term of a
contract must be given effect,” and courts should avoid
accepting interpretations that “render[] part of the writing
superfluous.”). And while it is true that the “mutual release”
provision extends to “any and all claims” that are “in any way
connected with” Remaining Sites Costs, “it is an accepted
principle that general words in a release are limited always to
that thing or those things which were specially in the
contemplation of the parties at the time when the release was
given.” Id. § 32:10; see also id. (“[S]pecific words [in a
release] will limit the meaning of general words if it appears
from the whole agreement that the parties’ purpose was
directed solely toward the matter to which the specific words
or clause relate.”). Here, the release’s general “in any way
                   ASARCO V. UNION PACIFIC                             21

connected with” language is restricted by its more specific
limitation to “costs incurred by UP.”

    Reading the contract the way Asarco suggests does not,
as the district court found, render the release “anything but
mutual.” ASARCO, 936 F. Supp. 2d at 1204. To the
contrary, the release of both parties’ claims regarding
response costs incurred by Union Pacific — the subject of the
parties’ settlement — has the effect of preventing both parties
from later claiming that their compromise amount as to those
costs was too high or too low in light of later developments.

    We therefore conclude that the UP Settlement is
ambiguous because it can be reasonably understood to release
only claims involving Remaining Sites Costs incurred by
Union Pacific. It was error for the district court to conclude
otherwise.3

                            CONCLUSION

    Although we agree with the district court that Asarco’s
FAC was timely, we conclude that the district court erred by
dismissing Asarco’s contribution claim on the basis of an
ambiguous settlement agreement. We therefore reverse the
district court’s dismissal of Asarco’s contribution action and
remand for further proceedings consistent with our opinion.

     REVERSED and REMANDED.



 3
    We decline to affirm dismissal of the action on the basis of any of the
additional grounds raised by Union Pacific because to do so would require
us to resolve disputed facts in Union Pacific’s favor. See Scott, 746 F.2d
at 1378.
