## Facts

- ASARCO, LLC, a mining and smelting company, and Union Pacific Railroad Company and Union Pacific Corporation operated for decades in northern Idaho’s Coeur d’Alene watershed.
- The EPA listed the Coeur d’Alene area as a CERCLA National Priorities List site in 1983, followed by decades of cleanup efforts and related litigation.
- In prior consolidated CERCLA actions, governments and a tribe sought response costs and natural resource damages from ASARCO and other parties.
- In 2009, during ASARCO’s bankruptcy reorganization, a federal court approved a consent decree resolving ASARCO’s CERCLA liability for the site; ASARCO agreed to pay $482 million.
- On June 5, 2012—three years after entry of the consent decree—ASARCO filed a CERCLA § 113(f) contribution action against Union Pacific to recover a share of the $482 million.
- ASARCO later filed a first amended complaint that expanded the claim to include an additional tract of land connected to the site.
- The district court dismissed under Rule 12(b)(6), concluding the claim was timely but barred by a 2008 settlement agreement between ASARCO and Union Pacific containing a mutual release.

## Issues

1. Whether Rule 6(a) governs calculation of CERCLA § 113(g)(3)(B)’s three-year limitations period for a § 113(f) contribution action, making a filing exactly three years after entry of a consent decree timely.
2. Whether an amended complaint expanding the geographic scope of a CERCLA contribution claim relates back under Rule 15(c)(1)(B) when it arises from the same site and cleanup costs.
3. Whether a 2008 mutual release governed by Texas law unambiguously released ASARCO’s later CERCLA contribution claim, permitting dismissal on the pleadings.

## Decision

- The Ninth Circuit reversed the Rule 12(b)(6) dismissal and remanded.
- The original complaint was timely because Rule 6(a) excludes the triggering day (entry of the consent decree) when computing a limitations period stated in years.
- The first amended complaint related back under Rule 15(c)(1)(B) because it arose from the same conduct, transaction, or occurrence as the original pleading, notwithstanding an earlier disclaimer of the additional tract.
- The 2008 mutual release did not unambiguously bar ASARCO’s CERCLA contribution claim; ambiguity made dismissal at the pleading stage improper.

## Legal Principles

- For CERCLA § 113(g)(3)(B) contribution limitations periods, Rule 6(a)’s computation method applies absent contrary statutory direction, excluding the day of the triggering event.
- Under Rule 15(c)(1)(B), an amendment relates back if it arises from the same conduct, transaction, or occurrence described (or attempted to be described) in the original pleading, even where the amendment expands factual detail or scope tied to the same core site and response costs.
- Under Texas contract law, a release is interpreted using ordinary contract principles; if the release language is reasonably susceptible to more than one interpretation, it is ambiguous and generally cannot support dismissal on the pleadings.

## Conclusion

The Ninth Circuit held that ASARCO’s CERCLA contribution action was timely under Rule 6(a), that its amended allegations related back under Rule 15(c), and that the parties’ prior settlement release was not sufficiently clear to defeat the claim at the Rule 12(b)(6) stage, requiring reversal and remand for further proceedings.


ASARCO, L.L.C. v. Union Pac. R.R. Co., 765 F.3d 999 (9th Cir. 2014)