FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

ASARCO, LLC,

Plaintiff-Appellant,

v.

UNION PACIFIC RAILROAD

COMPANY, a Utah corporation;

UNION PACIFIC CORPORATION,

Defendants-Appellees,

No. 13-35356

D.C. No.

2:12-cv-00283-

EJL

OPINION

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 DefendantsAppellees.

OPINION

CARNEY, District Judge:

ASARCO, LLC (“Asarco”) appeals the district court’s

dismissal of its contribution action brought under § 113(f) of

the ComprehensiveEnvironmental 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 unambiguouslyrelease 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 orfactual 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 “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

anniversarymethod. If the anniversarymethod 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 calendardate 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 ‘anyapplicable 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.2If 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 separatelydefined

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

broadlyrelated to CERCLA response costs incurred byUnion

Pacific. But this is not the only reasonable interpretation. 

The release provision could also plausiblymean 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 reasonablyunderstood 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.