The State of Colorado brought an enforcement action against defendants Power Engineering Company, Redoubt Limited, and Richard Lilienthal (collectively referred to as “PEC”) for violations of the Colorado Hazardous Waste Management Act. Plaintiff United States, acting on behalf of the Environmental Protection Agency (“EPA”), filed its own lawsuit against PEC for the same violations, seeking financial assurances. The district court denied PEC’s motion for summary judgment, finding that the EPA’s lawsuit was not barred by statute or by res judica-ta. We exercise jurisdiction pursuant to 28 U.S.C. § 1292(a)(1) and AFFIRM.
I. Background
Power Engineering Company has operated a metal refinishing and chrome electroplating business in Denver, Colorado since 1968. Redoubt Limited owns land and buildings leased and used by Power Engineering. Richard Lilienthal is an officer of both Power Engineering and Redoubt, as well as the sole shareholder of both companies. Each month Power Engineering produces over 1000 kilograms of waste, including arsenic, lead, mercury, and chromium. This waste is covered by the Resource Conservation and Recovery Act (“RCRA”), 42 U.S.C. §§ 6901-6992k, and is defined as “hazardous.” After the Colorado Department of Public Health and Environment (“CDPHE”) learned of a discharge of hexavalent chromium into the Platte River, it conducted inspections of PEC and discovered that chromium emanating from PEC was contaminating the groundwater. It also found that PEC treated, stored, and disposed of hazardous wastes without a permit. CDPHE issued a notice of violation on June 11, 1993, and an Initial Compliance Order in July 1994. CDPHE issued a Final Administrative Compliance Order on June 13, 1996, requiring PEC to comply with hazardous waste laws, implement a cleanup plan for chrome-contaminated soil, conduct frequent inspections, and submit periodic reports.
PEC failed to comply with this order, and CDPHE issued an Administrative Penalty Order on December 23, 1996, assessing civil penalties of $1.13 million. When PEC refused to pay the penalties, CDPHE brought suit in state court to’ force compliance with both orders. The Colorado state court found on March 23, 1999 that the Final Administrative Compliance Order and the Administrative Penalty Order were enforceable as a matter of law.
Before CDPHE issued its Final Administrative Compliance Order, the EPA had *1236 requested that CDPHE enforce RCRA’s financial assurance requirements against PEC. The EPA notified CDPHE that it would bring its own enforcement action if CDPHE failed to do so. When CDPHE did not demand financial assurances, the EPA filed its own suit against PEC.
The EPA and PEC filed cross-motions for summary judgment. PEC argued that the RCRA statute and res judicata barred the EPA from “overfiling” — which has been defined in this context as “[t]he EPA’s process of duplicating enforcement actions.”
Harmon Indus. v. Browner,
II. Discussion
We review the grant of summary judgment de novo, applying the same standard as the district court.
Wark v. United States,
A. Permissibility ofOverfiling
PEC contends that the district court erred in not following the Eighth Circuit’s interpretation of RCRA in
Harmon.
Under RCRA, a state may apply to the EPA for authorization to administer and enforce its own hazardous waste program if its program is equivalent to the federal program and provides adequate enforcement. 42 U.S.C. § 6926(b), (c). The
Harmon
court held that RCRA allows the EPA to overfile after providing notice to the authorized state only if the EPA withdraws authorization or if the state fails to initiate an enforcement action.
A state program authorized pursuant to RCRA operates “in lieu of’ the federal program. 42 U.S.C. § 6926(b). PEC contends that the “in lieu of’ language renders the EPA powerless to file a separate lawsuit when a state has been authorized to run its own program and initiates its own enforcement action. The EPA disagrees and interprets RCRA in its regulations to allow such overfiling. 40 C.F.R. §§ 271.16(c) note, 271.19;
see also United States v. Power Eng’g Co.,
Because the EPA is charged with the administration of RCRA,
Chevron v. NRDC
guides our review of its interpretation of the statute.
The EPA argues that Congressional intent to allow overfiling is demonstrated by 42 U.S.C. § 6928(a), which conditions EPA enforcement only on providing notice to an authorized state: “[T]he [EPA] Administrator may issue an order assessing a civil penalty for any past or current violation .... [T]he Administrator shall give notice to the State in which such violation has occurred prior to issuing an order or commencing a civil action under this section.” As another circuit court held, “Read in context, section [6928(a)] ... simply conditions the exercise of [federal] authority on the provision of prior notice.”
Wyckoff Co. v. EPA,
The EPA finds support for this interpretation in RCRA’s citizen suit provision, which explicitly limits authority for citizen suits. This provision states, “No [citizen suit] may be commenced ... if the [EPA] or State has commenced and is diligently prosecuting a civil or criminal action....” 42 U.S.C. § 6972(b)(1). No similar language is included in section 6928, which only requires notice. “[W]here Congress includes particular language in one section of a statute but omits it in another section of the same Act, it is generally presumed that Congress acts intentionally and purposely in the disparate inclusion or exclusion.” Br
own v. Gardner,
PEC argues, however, that several provisions of RCRA support its interpretation that RCRA unambiguously prohibits over-filing. PEC relies largely on section 6926(b), which provides that, once a state’s hazardous waste program has been approved under RCRA, “[s]uch State is authorized to carry out such program in lieu of the Federal program under this sub-chapter in such State and to issue and enforce permits....” 42 U.S.C. § 6926(b). PEC argues that, because an authorized state program operates “in lieu of’ the federal program, the EPA may not file an enforcement action after a state has done so. The linchpin of PEC’s argument “is that the term ‘program’ in § 6926 incorporates the exclusive responsibility to enforce criminal provisions penalizing the disposal of hazardous wastes.”
United States v. Elias,
The wording of section 6926(b) lends support to the EPA’s interpretation.
*1238
Power Eng’g,
The only other circuit court of which we are aware that has directly addressed the question acknowledged that “the EPA is correct that the ‘in lieu of language refers to the program itself.”
Harmon,
Even if we were to find that administration and enforcement were inexorably intertwined, we could only reach the Harmon court’s ultimate holding by “harmonizing” different sections of the statute:
Harmonizing the section 6928(a)(1) and (2) language that allows the EPA to bring an enforcement action in certain circumstances with section 6926(b)’s [sic 1 ] provision that the EPA has the right to withdraw state authorization if the state’s enforcement is inadequate manifests a congressional intent to give the EPA a secondary enforcement right in those cases where a state has been authorized to act that is triggered only after state authorization is rescinded or if the state fails to initiate an enforcement action.
PEC also relies upon section 6926(d) in support of its position that the statute does not allow overfiling. That section provides:
(d) Effect of a State permit
Any action taken by a State under a hazardous waste program authorized under this section shall have the same force and effect as action taken by the [EPA] under this subchapter.
42 U.S.C. § 6926(d). The Harmon court, construing “the Act as a whole,” found that this section applies broadly to any action authorized under this subchapter, including enforcement:
The state authorization provision substitutes state action (not excluding enforcement action) for federal action. It would be incongruous to conclude that the RCRA authorizes states to implement and administer a hazardous waste program “in lieu of’ the federal program where only the issuance of permits is accorded the same force and effect as an action taken by the federal government. ... Nothing in the statute suggests that the “same force and effect” language is limited to the issuance of permits but not their enforcement.
In our judgment, limiting the “same force and effect” language to the issuance of permits is not “incongruous” with RCRA as a whole.
Harmon,
PEC also argues that the language of the citizen suit provision supports its inter
*1240
pretation. That provision states that no citizen suit may be brought if “the [EPA] Administrator
or
State” is diligently pursuing a lawsuit. 42 U.S.C. § 6972(b)(1) (emphasis added). PEC contends that the choice of the word “or” instead of “and/or” indicates that Congress did not contemplate competing actions between the EPA and an authorized state.
Harmon,
In sum, PEC’s position is arguably supported by the “in lieu of’ and “same force and effect” language of section 6926, as well as the “or” instead of “and/or” language of section 6972(b)(1). On the other hand, PEC’s interpretation contradicts the plain language of section 6928, the wording of section 6926(b), and the structure of the statute. Moreover, PEC’s result is only reached by “harmonizing” sections 6928 and 6926 in a rather strained manner. Given these ambiguities and contradictions, we find that Congress has not “directly spoken to the precise question at issue.”
Chevron,
467 U.S.
at
842,
B. Res Judicata
PEC next argues that the EPA’s lawsuit is barred by the doctrine of res judicata. The question of application of res judicata to the facts, viewed in the light most favorable to the nonmoving party, is a pure question of law to be reviewed de novo.
Plotner v. AT & T Corp.,
“Under res judicata, a final judgment on the merits bars further claims by parties or their privies based on the same cause of action.”
Montana v. United States,
Privity requires “at a minimum, a substantial identity between the issues in controversy and showing that the parties in the two actions are really and substantially in interest the same.”
Lowell Staats Min. Co. v. Philadelphia Elec. Co.,
(1) required the [ ] lawsuit to be filed;
(2) reviewed and approved the complaint;
(3) paid the attorneys’ fees and costs;
(4) directed the appeal from State District Court to the Montana Supreme Court;
(5) appeared and submitted a brief as amicus in the Montana Supreme Court;
(6) directed the filing of a notice of appeal to this Court; and
(7) effectuated [the] abandonment of that appeal on advice of the Solicitor General.
Id.
at 155,
PEC argues, however, that the EPA “pulled” the “laboring oar” earlier in the process, when it ceded authority to the state to operate programs “in lieu of’ and “with the same force and effect” as the EPA.
Harmon,
Even if we agreed that the “laboring oar” could be “pulled” by such a delegation of authority,
Harmon
and
Rayonier
are distinguishable from the present case, and we find no other authority that would allow us to find privity based on the tenuous connection presented here. Unlike the Eighth Circuit in
Harmon,
we have found that states act in lieu of the EPA only with respect to administration of the program and issuance of permits. The EPA’s connection to the state’s litigation is therefore more limited than in
Harmon.
In
Rayo-nier,
the court did not follow the laboring oar analysis. Instead, the court relied largely on the identical interests of the state agency and the EPA.
III. Conclusion
We find that the RCRA statute is ambiguous, and we defer to the EPA’s reasonable interpretation that RCRA allows EPA overfiling. We also find that the EPA and CDPHE were not in privity, making the res judicata doctrine inapplicable. We therefore AFFIRM the ruling of the district court.
Notes
. Section 6926(e), rather than section 6926(b), allows for withdrawal of authorization. Section 6926(b) states when the EPA may deny a state's application for authorization.
