Court Opinion

ID: 9945038
Source: CourtListenerOpinion
Date Created: 2024-02-26 21:07:56.361019+00
Date Added: 2024-06-11T14:25:20.587537
License: Public Domain

02/26/2024

                                       DA 22-0406
                                                                                   Case Number: DA 22-0406

              IN THE SUPREME COURT OF THE STATE OF MONTANA

                                       2024 MT 36

MONTANA TROUT UNLIMITED, MONTANA
ENVIRONMENTAL INFORMATION CENTER,
TROUT UNLIMITED, EARTHWORKS, and
AMERICAN RIVERS,

          Plaintiffs and Appellees,

    v.

MONTANA DEPARTMENT OF ENVIRONMENTAL
QUALITY, and TINTINA MONTANA, INC.,

          Defendants and Appellants,

    and

STATE OF MONTANA, by and through THE OFFICE OF
THE ATTORNEY GENERAL, MEAGHER COUNTY,
and BROADWATER COUNTY,

          Defendants, Intervenors,
          and Appellants.

APPEAL FROM:        District Court of the Fourteenth Judicial District,
                    In and For the County of Meagher, Cause No. DV-20-10
                    Honorable Katherine M. Bidegaray, Presiding Judge

COUNSEL OF RECORD:

            For Appellant Tintina Montana, Inc.:

                    Dale Schowengerdt (argued), Landmark Law PLLC, Helena, Montana

                    Neil G. Westesen, Victoria A. Marquis, Crowley Fleck PLLP, Helena,
                    Montana

                    William W. Mercer, Matthew H. Dolphay, Holland & Hart LLP, Billings,
                    Montana
             For Appellant Montana Department of Environmental Quality:

                    Jeremiah Langston (argued), Department of Environmental Quality,
                    Helena, Montana

             For Appellant Broadwater County:

                    Cory Swanson, Broadwater County Attorney, Townsend, Montana

             For Appellant Meagher County:

                    Burt N. Hurwitz (argued), Meagher County Attorney, White Sulphur
                    Springs, Montana

             For Appellees:

                    Jenny Kay Harbine (argued), Benjamin J. Scrimshaw, Earthjustice,
                    Bozeman, Montana

                                                   Argued: June 21, 2023
                                                 Submitted: June 27, 2023
                                                  Decided: February 26, 2024

Filed:

                              qi5--6 A-- 4(
                    __________________________________________
                                      Clerk

Justice Beth Baker delivered the Opinion of the Court.
                                             2
¶1     The Montana Department of Environmental Quality and Tintina Montana

Incorporated appeal the Fourteenth Judicial District Court’s order revoking the permit that

DEQ granted Tintina to construct and operate the Black Butte Copper Mine. The District

Court revoked the permit after concluding that DEQ failed to adhere to two statutory

schemes governing the state permitting process—Montana’s Metal Mine Reclamation Act

(MMRA) and the Montana Environmental Policy Act (MEPA). Upon careful review of

DEQ’s administrative record, however, and applying the appropriate standards of review,

we conclude that the agency demonstrated compliance with both laws. We accordingly

reverse the District Court’s order and reinstate Tintina’s permit. We address three issues:

       1. Did DEQ satisfy MMRA and MEPA when it approved Tintina’s cemented
          tailings facility?

       2. Did DEQ satisfy MEPA by rationally evaluating the environmental impact of the
          mine’s total nitrogen discharges into Sheep Creek?

       3. Did DEQ satisfy MEPA when it considered and dismissed alternatives to the
          proposed action?

                 FACTUAL AND PROCEDURAL BACKGROUND

¶2     This case concerns the legality of a permit for a proposed copper mine along a key

tributary of the Smith River. The Smith River is an undisputed Montana treasure. It rises

in southern Meagher County and flows northwest between the Big Belt and Little Belt

Mountains, eventually joining the Missouri River outside of Great Falls. A 59-mile

segment of the Smith, with only one public put-in and take-out, provides anglers and other

recreationists with an iconic and coveted float trip. Given the Smith River’s popularity and

the Legislature’s desire to protect its natural scenic beauty and conserve fish and wildlife,
                                             3
the river is subject to a recreational permitting program—the only kind in the State.

See § 23-2-407, MCA. Each year, thousands of people apply for a permit to float the

Smith; the State awards about 1,000 permits each year.

¶3     In 2010, Tintina acquired mineral rights via lease agreements to nearly 2,000 acres

of private land bordering Sheep Creek, nineteen miles upstream from where Sheep Creek

feeds into the Smith. Tintina conducted licensed exploration of the acreage for five years,

located high-grade copper deposits, and, in December 2015, submitted a mine operating

permit application to DEQ per the MMRA. See § 82-4-335, MCA. Tintina proposed to

construct, operate, and reclaim the mine—named the Black Butte Copper Mine—over the

course of nineteen years (two years for construction, thirteen years for active mining, and

four years for reclamation and closure). Throughout the administrative process and

subsequent appeals, Tintina has emphasized the importance of mining copper to the

manufacturing of wind turbines and the shift to renewable energy technology. Intervenors

Meagher and Broadwater Counties emphasize the economic promise of the mine for their

communities in terms of increased employment and tax-base, along with the counties’

interest in protecting the Smith River.

¶4     The proposed mine would be underground, accessing copper deposits via a

17-by-17-foot-diameter surface portal. Nearly 19,000 feet of underground access ramp

and drifts would be developed, but Tintina anticipates a surface disruption of only 300 of

the 2,000 acres. Tintina estimates that its operations would extract 15.3 million tons of

                                            4
material—14.5 million tons of copper-enriched rock, also known as copper ore, and 0.8

million tons of waste rock.

¶5     Tintina plans to process the copper ore into a copper concentrate on site, use trucks

to ship the concentrate for sale, and store on site an estimated 12.9 million tons of tailings

(material left over after processing ore). Proposed surface facilities include a processing

plant, Cemented Tailings Facility (CTF), water treatment plant, various processing and

storage ponds, wet-well and pipeline, buried drainpipes, roads, stockpiles, powerline,

ditches, roads, parking, and fencing. Just under half, (45%) of the tailings would be mixed

with cement and other binder and deposited underground to backfill the mined-out voids.

The rest (55%) would be mixed with a lower concentration of cement and other binder and

placed in the above-ground CTF. Of Tintina’s entire proposed design, the only challenged

aspects involve the CTF and the handling of groundwater pumped from underground shafts

and voids. The CTF and groundwater pumping system are described in further detail in

our discussion.

¶6     Tintina engaged in nearly five years of review with DEQ pursuant to various

statutes. This process resulted in an administrative record of nearly 90,000 pages. Three

times, DEQ found and detailed numerous substantive deficiencies in Tintina’s application.

Tintina submitted extensive revisions each time before DEQ deemed the application

minimally complete in 2017. DEQ then began environmental review under MEPA. DEQ

held an initial scoping public comment period in the fall of 2017, with four public meetings

(one each in Great Falls, White Sulphur Springs, Helena, and Livingston). DEQ assembled

                                              5
a team of seventeen internal experts and forty-two outside consultants, including

hydrologists, geologists, geochemists, engineers, and biologists. This team drafted an

environmental impact statement (EIS), which was issued on March 11, 2019. DEQ then

opened a public comment period on the Draft EIS through May 2019. This comment period

included three in-person meetings (one each in Great Falls, Livingston, and White Sulphur

Springs), two online meetings, and mail and e-mail comments. The Final EIS, issued in

February 2020, compiled and responded to public comments.

¶7     On April 9, 2020, DEQ issued its Record of Decision on Tintina’s application for a

mine operating permit.1 Out of three alternatives identified during environmental review

(not permitting the mine, permitting the mine without modification, or permitting the mine

with modification), DEQ opted to permit the mine with modification.2 DEQ explained

that, in coming to its decision, it considered all relevant scientific information—as well as

scientific uncertainty and risk—public concerns and opposing viewpoints, and the various

applicable state laws. DEQ recognized the proximity of the proposed mine to the Smith

River and “the importance to the State of the Smith River, in terms of ecological,

1
 In the same record of decision, DEQ issued a Montana Pollutant Discharge Elimination System
(MPDES) permit under the Montana Water Quality Act. Appellees did not challenge the MPDES
permit, and it is not at issue. MTU and other conservation groups did, however, challenge the
Montana Department of Natural Resources and Conservation’s determination regarding Tintina’s
application for a beneficial use permit under the Montana Water Use Act, Title 85, chapter 2,
MCA. That challenge is pending before this Court in a separate appeal, S. Ct. No. DA 23-0268.
2
 The modification added a requirement that Tintina backfill additional mineralized mined-out
voids with cemented paste tailings.
                                            6
recreational, and economic values,” but asserted that no potential environmental impacts

on the Smith River were identified.

¶8    Montana Trout Unlimited and various other conservation organizations

(collectively MTU) sought judicial review of DEQ’s decision in the District Court and

moved for summary judgment, arguing that the agency’s issuance of the permit violated

MMRA and MEPA.           DEQ, Tintina, and Meagher and Broadwater Counties filed

cross-motions for summary judgment.3 After hearing oral argument, the District Court

granted summary judgment to MTU on three alternative grounds: (1) DEQ did not

rationally consider and ensure the safety and stability of the CTF, and therefore violated

MMRA and MEPA when it issued the permit; (2) DEQ failed to rationally evaluate the

environmental impact of the mine’s nitrogen discharges to Sheep Creek and therefore

violated MEPA; and (3) DEQ failed to reasonably analyze alternatives to the proposed

project, also in violation of MEPA.

¶9    On June 21, 2023, this Court heard oral argument on DEQ’s and Tintina’s appeals

of the District Court’s order and took the matter under advisement.

                              STANDARD OF REVIEW

¶10   Summary judgment is appropriate where there is no genuine dispute of material fact

and the movant is entitled to judgment as a matter of law. M. R. Civ. P. 56(c)(3). We

review summary judgment rulings de novo, applying the same criteria the district court

3
  The State of Montana also opposed MTU’s motion for summary judgment but ceased its
involvement after the District Court avoided the constitutional issue.
                                                7
applied. Clark Fork. v. Mont. Dept. of Envtl. Quality, 2008 MT 407, ¶ 19, 347 Mont. 197,

197 P.3d 482 [hereinafter Clark Fork I].

¶11    A court carefully reviews an agency’s decision to determine whether the decision

was “arbitrary, capricious, unlawful, or not supported by substantial evidence.” Clark

Fork I, ¶ 21.4 “Substantial evidence is evidence that a reasonable mind might accept as

adequate to support a conclusion. It consists of more than a mere scintilla of evidence but

may be less than a preponderance.” Mont. State Univ.-Northern v. Bachmeier, 2021 MT

26, ¶ 30, 403 Mont. 136, 480 P.3d 233 (citation omitted). An agency must show that it

examined the relevant data and must articulate a satisfactory explanation for its action,

“including a rational connection between the facts found and the choice made.” Clark Fork

I, ¶ 47. A court does not merely defer to an agency without close review of the record and

satisfaction that the agency made a reasoned decision without clear error of judgment.

Clark Fork I, ¶ 21 (citation omitted).

¶12    Nevertheless, “the ultimate standard of review is a narrow one.” Clark Fork I, ¶ 27.

We recognize that the Legislature has entrusted certain scientific and technical decisions

to expert agencies, and our review of such decisions raises constitutional

separation-of-powers considerations.         MEIC, ¶ 20.       “To balance these constitutional

4
  Montana’s Administrative Procedure Act governs judicial review of “contested cases.” Title 2,
chapter 4, part 7, MCA. MAPA defines “contested case” as “a proceeding before an agency in
which a determination of legal rights, duties, or privileges of a party is required by law to be made
after an opportunity for hearing. The term includes but is not restricted to ratemaking, price fixing,
and licensing.” Section 2-4-102(4), MCA. The underlying administrative proceeding in this case
was not a contested case for purposes of MAPA; our review thus is performed under the standards
discussed here. See Mont. Envtl. Info. Ctr. v. Mont. Dep’t of Envtl. Quality, 2019 MT 213, ¶ 19,
397 Mont. 161, 451 P.3d 493 [hereinafter MEIC].
                                                  8
concepts and to ensure that agency decision-making is scientifically-driven and

well-reasoned, this Court affords ‘great deference’ to agency decisions implicating

substantial agency expertise.” MEIC, ¶ 20 (citation omitted). In reviewing the agency’s

decision, “[t]he Court’s focus is on the administrative decision-making process rather than

the decision itself.” Water for Flathead’s Future, Inc. v. Mont. Dep’t of Envtl. Quality,

2023 MT 86, ¶ 11, 412 Mont. 258, 530 P.3d 790 (quoting Park Cty. Envtl. Council v. Mont.

Dep’t of Envtl. Quality, 2020 MT 303, ¶ 18, 402 Mont. 168, 477 P.3d 288 [hereinafter Park

Cty. Envtl. Council]. Courts should not substitute their own judgment for that of the agency

by asking whether the agency’s decision was the “correct” one scientifically, morally, or

politically. Courts instead interpret the law and determine if the agency made its decision

with sufficient information or if “the decision was so at odds with the information gathered

that it could be characterized as arbitrary or the product of caprice.” Clark Fork I, ¶ 27.

Importantly, “[a]n agency decision is not arbitrary or capricious merely because the record

contains inconsistent evidence or evidence which might support a different result.” Clark

Fork. v. Mont. Dep’t of Natural Res. & Conservation, 2021 MT 44, ¶ 34, 403 Mont. 225,

481 P.3d 198 [hereinafter Clark Fork II] ( quotations omitted). A decision is arbitrary and

capricious only if “apparently random, unreasonable[,] or seemingly unmotivated based on

the existing record.” Water for Flathead’s Future, ¶ 12 (citations and quotations omitted).

                                      DISCUSSION

¶13    Issue One: Did DEQ satisfy MMRA and MEPA requirements when it approved the
       proposed cemented tailings facility?

                                             9
MMRA

¶14     MMRA sets forth a series of substantive requirements for the permitting of metal

mines in Montana. Title 82, chapter 4, part 3. In passing MMRA, the Legislature declared

that mining “is a basic and essential activity making an important contribution to the

economy of the state and the nation.” Section 82-4-301(3), MCA. At the same time, the

Legislature recognized that mining necessarily creates disturbances and produces waste

and that proper reclamation of mined land “is necessary to prevent undesirable land and

surface water conditions detrimental to the general welfare, health, safety, ecology, and

property rights of the citizens of the state.” Section 82-4-301(3), MCA. The Legislature

found that MMRA balanced the need to mine with the need for subsequent beneficial use

of land. It further expressed that its intent in passing MMRA was to “provide adequate

remedies for the protection of the environmental life support system from degradation and

provide adequate remedies to prevent unreasonable depletion and degradation of natural

resources.” Section 82-4-301(2)(a), MCA. In sum, MMRA’s purposes include allowing

mining as an economically beneficial and practical activity; mitigating or preventing

harmful offsite environmental impacts; and providing for reclamation. Section 82-4-302,

MCA.

¶15     In 2015, the Legislature revised MMRA to establish standards for tailings storage

facilities.5 2015 Mont. Laws ch. 399. The standards make clear that tailings storage

5
    A tailings storage facility is a “facility that temporarily or permanently stores
tailings . . .,” excluding a facility that “stores 50 acre-feet or less of free water or process solution.”
Section 82-4-303(34), MCA. DEQ initially determined that Tintina’s proposed CTF met the
exception (storing less than 50-acre feet of water or process solution) and thus did not need to meet
                                                     10
facilities are to be “designed, operated, monitored, and closed in a manner that: meets

state-of-practice engineering design standards; uses applicable, appropriate, and current

technologies and techniques as are practicable given site-specific conditions and concerns;

and provides protection of human health and the environment . . . .”                        Section

82-4-301(2)(b), MCA. The Legislature declined to issue prescriptive regulations of tailings

storage facilities, opting instead to allow “for adaptive management using evolving best

engineering practices based on the recommendations of qualified, experienced engineers.”

Section 82-4-301(2)(c), MCA; see also § 82-4-301(3), MCA (“Mining . . . take[s] place in

diverse areas where geological, topographical, climatic, biological, and sociological

conditions are significantly different, and the specifications for . . . tailings storage facilities

must vary accordingly.”).

¶16    Under the 2015 revisions, an applicant for a mine operating permit must include in

its application to DEQ:

       [A] plan detailing the design, operation, and monitoring of impounding
       structures, including but not limited to tailings impoundments and water
       reservoirs, sufficient to ensure that the structures are safe and stable. For a
       tailings storage facility, this requirement is met by submission of a
       design document pursuant to 82-4-376, a panel report pursuant to
       82-4-377, and a tailings operation, maintenance, and surveillance
       manual pursuant to 82-4-379 prior to issuance of a draft permit.

MMRA’s substantive standards for tailings storage facilities. The District Court disagreed,
concluding that the CTF did need to meet MMRA’s standards. Neither Tintina nor DEQ takes
issue on appeal with application of the statute. Tintina’s initial application to DEQ in 2015 in fact
acknowledged the statutory amendments and stated that “the CTF will be designed and constructed
in compliance with all applicable requirement[s] for construction of tailings impoundments,
including the newly enacted tailings additions to the mine reclamation laws (Senate Bill 409).”
                                                 11
Section 82-4-335(4)(l), MCA (emphasis added to 2015 additions). Each of the referenced

statutes explains in detail the three requirements for a tailings storage facility to be

considered a “safe and stable” structure: a design document containing thirty-one different

descriptions and analyses (§ 82-4-376, MCA); review of the design document by an

“independent review panel” (IRP) (§ 82-4-377, MCA); and a tailings operation,

maintenance, and surveillance manual (TOMS manual) (§ 82-4-379, MCA).

MEPA

¶17    During its review and decision-making, DEQ also must comply with MEPA. Title

75, chapter 1, MCA. MEPA entails various statutory procedures and corresponding

administrative rules to ensure environmental review by state agencies. Under MEPA,

agencies must prepare an Environmental Impact Statement (EIS) for all projects

“significantly affecting the quality of the human environment.” Admin. R. M. 17.4.607

(1989); § 75-1-201(1)(b)(iv), MCA. The EIS describes the proposed action, the current

environmental conditions in the affected area, and the action’s potential impacts on the

environment. Admin. R. M. 17.4.617(1), (3), (4) (1989). The EIS also analyzes and

discusses reasonable alternatives (including a no-action alternative), mitigation,

stipulations, tradeoffs among reasonable alternatives, and the agency’s preferred course of

action. Admin. R. M 17.4.617(5) - (9) (1989). The public has opportunity to comment on

the scope of the review process and on the draft EIS once issued; the final EIS must respond

to substantive comments received. Admin. R. M. 17.4.615, 17.4.619 (1989). MEPA is

meant to “encourage productive and enjoyable harmony between humans and their

                                            12
environment”; “protect the right to use and enjoy private property free of undue

government regulation”; and “promote efforts that will prevent, mitigate, or eliminate

damage to the environment and biosphere and stimulate the health and welfare of humans.”

Section 75-1-102(2), MCA.

¶18    In reviewing for MEPA compliance, courts ask whether an agency took a “hard

look” at the environmental impacts of a given project or proposal. Mont. Wildlife Fed’n v.

Mont. Bd. of Oil & Gas Conservation, 2012 MT 128, ¶ 43, 365 Mont. 232, 280 P.3d 877

(citation omitted). “[The Court] does not take a hard look itself but requires that the agency

does so. The Court focuses on the validity and appropriateness of the administrative

decision-making process without intense scrutiny of the decision itself.” Mont. Wildlife

Fed’n, ¶ 43 (quoting Clark Fork I, ¶ 47).

Issue Preservation

¶19    We address initially the contentions of DEQ and Tintina that MTU failed to preserve

during the administrative process its claims regarding tailings flowability and liquefaction,

and that this Court accordingly may not review MTU’s challenges on those grounds. The

District Court concluded that claims brought under MMRA do not need to meet MEPA

exhaustion requirements and that, regardless, MTU preserved each issue. MTU maintains

that the court correctly held that MEPA exhaustion is not required for claims brought under

MMRA or, alternatively, that all issues were adequately raised during the public comment

period.

                                             13
¶20       In a challenge to a DEQ decision or to the adequacy of its environmental review,

MEPA prohibits courts from considering “any information, including but not limited to an

issue, comment, argument, proposed alternative, analysis, or evidence, that was not first

presented to the agency for the agency’s consideration prior to the agency’s decision or

within the time allowed for comments to be submitted.” Section 75-1-201(6)(a)(iii), MCA.

We agree with MTU that it minimally preserved issues of flowability and liquefaction

during the administrative process and thus do not reach the issue whether MEPA

exhaustion is required for claims brought directly under MMRA.

¶21       MTU points to various comments on the Draft EIS and DEQ responses in the Final

EIS to support its preservation of the flowability issue. For example, one commenter

stated, “Consideration should be given to adding 4% cement binder to surface-disposed

tailings to allow them to set up more quickly.” DEQ responded, “Increasing the cement

and binder content in the paste tailings in either location would not provide additional

environmental benefits, and if too much cement and binder were added, it would not be

possible to pump the tailings through a pipeline.” In response to a different comment, DEQ

stated:

          The small quantity of cement proposed to be added to the paste tailings is not
          intended to delay or prevent ARD [Acid Rock Drainage] formation; rather,
          it is to provide structural strength and to change the physical properties of the
          tailings to a stable, non-flowable material with low hydraulic
          conductivities . . . . These sections also note that either cement addition rate
          would result in a tailings deposit sufficiently stable to maintain structural
          integrity in the event of an embankment failure (i.e., the tailings deposit
          would remain in place even if the dam did not). Paste tailings do not present
          the risk of catastrophic failure that is associated with conventional saturated
          tailings impoundments.

                                                 14
Even though these statements arose in the context of oxidation and acid formation of the

tailings, their substance indicates that the public was concerned about, and DEQ addressed,

the structural integrity of the surface tailings.

¶22    Similarly, the issue of liquefaction was preserved in at least the following comment:

       In particular, the Draft EIS arbitrarily ignores the potential that the CTF
       containment system will fail. The Draft EIS appears to acknowledge that a
       ‘release of tailings’ is possible ‘in response to impoundment failure or
       seismic events,’ Draft EIS at 3.5-24, but the Draft EIS makes no attempt to
       quantify the risk of such failure, characterize the environmental
       consequences of tailings release, or provide ‘reasonable assurance’ that
       tailings CTF impoundment failure ‘will not occur.’ ARM 17.4.608(1)(b).

DEQ’s response to another comment concerned about the stability of the tailings stated

that the dewatering process “causes the material to have a lower permeability,

which . . . precludes liquefaction during earthquakes . . . .”     Comments, despite not

necessarily using the word “liquefaction,” provided sufficient clarity such that DEQ

understood the issue and used its expertise to resolve the claim, explicitly addressing

liquefaction in its responses. Cf. Vote Solar v. Mont. Dep’t of Pub. Serv. Regulation, 2020

MT 213A, ¶ 48, 401 Mont. 85, 473 P.3d 963 (describing the requirement under MAPA to

raise certain questions before an agency with “enough clarity such that the decision maker

understands the issues raised” before raising them in judicial review). We accordingly

review MTU’s claims on the merits.

Non-Flowable Mass

¶23    The District Court concluded that DEQ violated MMRA and MEPA “by failing to

evaluate or respond meaningfully to record evidence that the proposed design for Tintina’s

                                               15
tailings facility does not ‘ensure’ that this impounding structure will remain ‘safe and

stable,’ § 82-4-335(5)(l), MCA, and may not effectively contain toxic mine waste.” The

court relied on evidence that Tintina expects, in the court’s words, “new layers of 2 percent

cement-paste tailings to take 28 days to set fully at the facility.” The court reasoned that

Tintina’s plan to layer tailings, on average, every seven to fifteen days, would prevent the

tailings from forming a stable, non-flowable mass. The court also stated that the record

showed that reducing binder content of the surface tailings “significantly increases their

drying time, making it a near certainty that lower layers with just 0.5 percent binder content

will not have set before fresh tailings are deposited on them.”

¶24    DEQ and Tintina argue that the court “replaced DEQ’s extensive review and

expertise with its own misinterpretations of inapposite record evidence.” They contend

that the court: confused the difference between ultra-thickened cemented paste tailings

setting into a non-flowable mass and those same tailings achieving “final set”; failed to

consider evidence supporting the stability of ultra-thickened tailings notwithstanding

binder content; ignored the embankment, high-density polyethylene (HDPE) liners, and

pump system as additional safety mechanisms of the CTF; and discounted their intentional

plans for operational flexibility and ongoing monitoring given anticipated varying weather

conditions and tailings characteristics. MTU responds that the court correctly enforced

Montana law when it determined that DEQ arbitrarily and unlawfully issued a mining

permit without record assurance—beyond mere statements—that the tailings will be non-

flowable.

                                             16
¶25     Careful review of the reports and rationales leading to the proposed and permitted

CTF leads us to conclude, as explained below, that the record contains substantial evidence

to support DEQ’s determination that the surface tailings would form a stable, non-flowable

mass.

Dewatered and Cemented Paste Tailings

¶26     To manage tailings at the Black Butte Copper Mine, Tintina proposes to process and

store them on site in the CTF. Processing the extracted ore and separating out the copper

concentrate would produce a tailings slurry. The slurry first would be dewatered “using a

separate high-rate thickener and flocculent” to achieve an initial 60% density. The tailings

would be further dewatered using a pressure filter, resulting in an estimated 70-85%

density. The result would be an “ultra-thickened” paste. Tintina’s proposal relied on

research that ultra-thickened paste tailings—as opposed to slurry tailings (25-60% solids)

and thickened tailings (57-67% solids) which can flow with gravity—“can flow with the

application of pressure, much like cake-frosting which only flows out of a tube onto a cake

under pressure.” Filtered tailings (>80% solids), conversely, “are too dry to flow, even

under pumping pressure, and must be transported mechanically with trucks or belts.”

¶27     About 45% of the ultra-thickened paste tailings would be mixed with 4% binder (a

combination of cement and slag) and pumped underground to fill mined-out voids. MTU

does not take issue with Tintina and DEQ’s proposal for these backfill tailings. The

remaining ultra-thickened paste tailings (about 55%) would be mixed with 0.5-2% binder

(a combination of cement, slag, and fly ash) and pumped to the above-ground CTF for

                                            17
deposition. Tintina proposes to deposit the cemented paste tailings into the CTF in thin

successive layers, also known as “thin lifts,” on average every seven to fifteen days, but

never longer than every thirty days. The layers would be deposited in a slope formation

for proper drainage of rainfall; the thickness of the layers would depend on operational

effectiveness, determined through ongoing monitoring and assessment. Tintina proposes

to add cement to ultra-thickened paste tailings to “reduce potential flow, reactive surface

area, and dust generation.”

Knight Piésold Working Group

¶28    In coming to the above design for surface tailings storage, Tintina convened a

working group of eighteen scientists and engineers from Tintina itself, the mining

consulting firm Knight Piésold, and several other firms. The group identified and evaluated

six feasible tailings storage methods and selected the most appropriate method for the

specific project and location.6 The group’s work was based on site-specific meteorological,

geotechnical, and hydrogeological studies completed or contracted by Knight Piésold. The

studies were submitted as part of Tintina’s application to DEQ. Each member of the group

selected their first, second, and third choice of method, given the selection criteria.

Selection criteria included effective and efficient tailings management and “minimizing

potential environmental impacts including facility stability, environmental risk[,] and

minimizing impacts to wetlands.” In striving to meet these criteria, the group considered,

6
  The six possible methods identified were: conventional tailings slurry deposition; dry stack
tailings; depyritized ultra-thickened sub-aqueous deposition; two-cell ultra-thickened depyritized
and pyrite concentrate; paste tailings with 4% cement content; and paste tailings with 2% cement
content.
                                                18
among other factors, the ore body, tailings characterization—including “known rheological

characteristic and geochemistry,” waste rock characterization, site location, and cost.

¶29    After taking a weighted average of each member’s selections, the group’s clear first

choice was to store the surface paste tailings with reduced (0.5-2%) cement content. The

group identified that “all of the pros and cons identified for the 4 percent paste tailings

alternative were also identified for the 2 percent alternative.” The pros of both methods

included: a deposit into the CTF that would be “sufficiently stable to maintain structural

integrity in the event of an embankment failure”; reduced embankment costs; reduced dust

generation; and reduced evaporative water losses. The cons of both options included that

they would require a separate process water storage pond and that there was potential for

oxidation on the surface between deposition of layers.7 The group found that the only

difference was that “the 2 percent alternative has a lower operating cost than does the 4

percent alternative while still providing sufficient structural integrity for the deposited

cemented paste.”

Ontario Cylinder Tests

¶30    One of the studies on which the group based its recommendations was experimental

testing of tailings material performed by a laboratory in Ontario, Canada. In 2015, the lab

received a limited quantity of solid materials drilled from the proposed mine site. The lab

prepared samples using the sourced materials, adding water to achieve a range of solid

content and varying ratios of cement, fly ash, and slag. The lab aimed to achieve two

7
  Oxidation is the alteration of rock by the addition or in the presence of oxygen. The oxidation
issue is addressed below.
                                                19
properties desirable to Knight Piésold in the hypothetical surface tailings: 1) a slump of 7-9

inches to ensure paste pumpability into the CTF; and 2) non-flowability once deposited.

The lab and Knight Piésold sought the additional property of “unconfined compressive

strength” in tests for backfill tailings, which would experience pressures underground. The

lab explicitly did not seek unconfined compressive strength for the surface tailings because

the material would be “fully contained and laterally supported in the depositional

environment.”

¶31    Twenty samples were cast as cylinders measuring 2-by-4 inches and 3-by-6 inches.

Additional samples were cast as cones measuring 4-inch (top) by 8-inch (base) by 12-inch

(height). Samples were initially cured at 70 degrees Fahrenheit and 100% relative humidity

and, once demolded, tested for slump and unconfined compressive strength.8 The lab

conducted trial tests of samples with a range of solid content from 75% to 85% and

measured “cone slump” with samples containing no binder (0%), 2% binder, and 4%

binder. Experimenters stopped increasing the total solid content “[w]hen the mix became

very stiff.”   The results demonstrated that increased cement content generally was

accompanied by increased initial strength (lower slump). The results also demonstrated

that increased total solid content was accompanied by increased initial strength. For

example, tailings with a high total solid content (84%) and 0% binder slumped 0.39 inches

in the cylinder sample and 3.35 inches in the cone sample, whereas tailings with lower total

8
 All samples were prepared and cured in accordance with the American Society for Testing and
Materials’s “Standard Practice for Making and Curing Concrete Test Specimens” and “Standard
Test Method for Slump of Hydraulic Cement Concrete.”
                                             20
solid content (79%) and 4% binder slumped more (.59 inches in the cylinder sample and

8.1 inches in the cone sample). Thus, the results demonstrated that the desirable slump

range was achievable with 0% binder and a high total solid content. The experimenters

identified the following, among others, as significant conclusions:

       1. The optimum [total solids content] for the 2% binder mix is 79.5% at a
          cone slump of 8.3 [inches].
       2. The optimum [total solids content] for the 4% binder mix is 79% at a cone
          slump of 8.1 [inches].
       3. The 2% binder mix does not achieve final set until approximately 28 days
          age.
       4. The 4% binder mix achieves final set after approximately 96 hours
          (4 days).

¶32    Based on the testing results, a Senior Lead Engineer with the lab sent a

memorandum to Tintina that recommended the Black Butte Copper Mine use a range of

0.5-2% binder for the surface tailings and an increased 4% binder for the underground

back-fill tailings to “ensure adequate strength.” The engineer advised:

       The cemented paste tailings placed in the surface Cemented Tailings Facility
       is spread in thin layers on the surface and is not required to achieve
       compressive strength for support. The addition of binder (0.5% - 2.0%, by
       weight) for cemented paste tailings is intended to ultimately change the
       pumpable paste into a dry, consolidated material.

The lab analyzed the differences between the humidity and temperatures of the

underground tailings and surface tailings. The memo explained that a nine-inch slump

paste consistency would be achieved by adding water in order to pump the cemented paste

through the long, horizontal pipelines, which would avoid plugging of the pipelines. The

lab concluded that the more cemented underground tailings would be less likely to

discharge bleed water and more likely to evaporate water from the wet paste tailings’

                                            21
surface. The memo advised that the surface tailings, which would be spread in thin layers

above ground and contain a lower cement content, would be more likely to discharge bleed

water and less likely to evaporate water from the paste’s surface than the underground

tailings. The lab anticipated bleed water to be 3-5% of the surface tailings’ weight and to

be “noticeable for a few days, until cemented paste tailings are consolidated.”

Enviromin Report on Surface-Placed Cemented Paste Tailings

¶33    To come to its surface tailings proposal, Tintina also relied on a white paper report

prepared by Enviromin, a Bozeman-based consulting firm specializing in geochemistry.

The report addressed “Surface-Placed Cemented Paste Tailings,” compiling case studies

and research regarding the use of cemented and uncemented paste tailings. The report

concluded that surface placement of cemented paste tailings was an innovative and logical

application of two proven technologies: cemented paste tailings backfill and surface

placement of paste tailings. The report stated that the dual approach reduced “the long-term

risks associated with tailings dams (subaqueous tailings impoundments)” and lessened

“potentially unfavorable environmental conditions observed in traditional tailings

facilities, such as dust and water quality impacts.”

¶34    The report stated that the use of surface paste tailings without binder was first

patented in 1996 and that operational use first occurred in 2003. The report stated that

“[s]ubsequent application of this technology has shown that it can be tailored to fit

site-specific geotechnical and environmental requirements . . . .” The report shared

research that although “seepage from surface-placed paste tailings is extremely unlikely,

                                             22
because they have very low hydraulic conductivity by design, any potential seepage to

groundwater could be mitigated with the use of clay or synthetic liners.” Surface paste

tailings without binder reduced costs, but a few problems persisted, including:

“over-topping, erosion of paste within the facility (which increases pressure on dams), and

potential for static liquefaction accompanied by static or seismic slope instability.”

¶35    The Enviromin Report referenced more than 80 articles and studies, identifying five

mines across the globe that placed uncemented paste tailings in surface facilities. A 2003

study about the Bulyanhulu Mine in Tanzania—which uses no binder—shared that the

facility deposited lifts every five days to prevent oxidative weathering of exposed surfaces.

The same study noted “that addition of the paste in thin lifts, with a maximum thickness of

30 cm, allowed for sufficient desiccation (drying) to provide required geotechnical

stability.” The Enviromin Report stated that, per numerous cited studies, the Bulyanhulu

Mine “is generally considered a successful facility.”

¶36    The Enviromin Report went on to analyze the use of cemented paste tailings.

Although researched at the lab-scale for more than fifteen years, the cemented paste tailings

method “has only been partially implemented at the facility scale at a single known

facility.” A 2016 study—one of several cited and described in the report—continued the

research of a 2011 study that had examined placement of cemented paste tailings layers

within layers of uncemented paste tailings. The new 2016 study examined the effect of

adding a final cemented paste layer by applying seven wetting and drying cycles and

conducting post-test examinations of the microstructure within the layers using destructive

                                             23
sampling techniques. Results indicated “that drying of deeper layers of paste tailings

appears to have been inhibited by addition of a final cemented-paste layer.” The Enviromin

Report relied on other studies in concluding that surface cemented paste tailings required

less strength than backfill tailings; that binder proportion can be varied throughout

operations to meet project needs; that binder selection and amount are site-specific; and

that surface cemented paste tailings posed an extremely low-to-no risk of catastrophic

failure. Noting a 2017 “United Nations call for zero-failure standards in tailings facility

design,” the report summarized, in part: “The utilization of cemented-paste tailings in a

surface facility, while acknowledged as a very expensive approach, is the highest level of

tailings safety management and goes well beyond the recommendations of the 2017 United

Nations report.” It concluded that “the integration of two well-studied technologies”—

cemented-paste tailings backfill and surface-placed tailings (to include a cemented-paste

binder)—in combination with other safeguards such as facility liners, “is a

best-management practice that offers the greatest potential for a ‘zero-failure’ facility.”

Engineered Embankment

¶37    Tintina proposes to locate the CTF against a hillside, bordered on three sides by

natural topography. The fourth side would be an engineered embankment made from free

draining rockfill, which is considered not susceptible to liquefaction and more stable than

an embankment made from tailings. The embankment would be constructed on bedrock,

which is not expected to deform, creep, or displace during an earthquake event. Tintina

engineered the embankment, as required by MMRA, to withstand the “maximum credible

                                             24
earthquake”; the 1-in-10,000-year earthquake event; the “maximum flood event”; and the

1-in-500 year, 24-hour flood event. See § 82-4-376(2)(i), -376(2)(cc), MCA. When

analyzing for various hazards (foundation and slope instability, overtopping, and internal

erosion and piping), the probability of failure of the embankment was designated as either

“not credible” or “very low.” The Dam Breach Risk Assessment prepared by Knight

Piésold clarifies that the CTF embankment is not designed as a water-retaining

impoundment and that breach of the embankment and a tearing of the liner system is a

“very unlikely event.” In such an unlikely event, Knight Piésold expected that the

cemented paste tailings, considered to be a non-flowable mass, “may slump in place, but

will not flow out to the downstream receiving environment.”

Liner and Pump System

¶38    Lining the bottom of the CTF would be two HDPE liners with geonet and geotextile

material above, between, and below them. To collect water from rain and flooding and

any bleed water from the cemented paste tailings, a rock drain would be placed above the

liners, another drain between the two liners (in the improbable event water escapes the first

liner), and a final drain below both liners. Three high-capacity pumps would remove

collected water to a separate facility for treatment. To help reduce the potential for seepage

from the facility, Tintina would use “vibrating wire piezometers” above the two liners “to

measure the pore water pressures within the tailings and monitor the performance of the

drainage management systems.”

                                             25
¶39    Near closure of the mine, the uppermost layer of paste tailings would contain

additional binder (4%) to decrease the potential for dust, increase surface strength, and

create a more durable surface for equipment to perform reclamation activities. Tintina

would take steps to remove any remaining water before installing a third HDPE liner on

top of the final layer of cemented paste tailings. The third liner would be welded to the

existing liner system, completely encapsulating the tailings, and then covered with five feet

of non-reactive fill material and soil to be revegetated. “Any seepage or contact water

within the liner, during the reclamation steps or following closure, would be captured by

the internal sump and pumped to the [Water Treatment Plant, (WTP)].” DEQ determined

that Tintina’s proposed liner, drain, and pump system was the “best available technology”

and a “best management practice” with “proven success in mining, municipal waste

handling, and other industrial applications.”

Operational Flexibility & Ongoing Monitoring

¶40    Throughout Tintina’s application and DEQ’s review materials, the importance of

operational flexibility and ongoing monitoring of the deposition of the cemented tailings

is emphasized. Tintina states in its application that it “may seek to optimize performance

of the cement and binder additions over time operationally” and that other “binders and

different ratios of binders may be used” in the surface tailings with the goal being “to

provide a mass with non-flowable characteristics.” Tintina further states, “[a]dditional

paste design mixes may be tested in the future to optimize the effectiveness for each binder

                                             26
type to meet the requirement for a non-flowable mass and weathering responses of the

material in the CTF.”

¶41    This flexibility accords with the recommendations of DEQ’s consultant,

Environmental Resource Management (ERM). ERM reviewed the Ontario lab’s test

results and conclusions and analyzed Tintina’s proposal to use 0.5-2% binder in the surface

tailings. DEQ specifically asked ERM to study whether a higher cement content should be

required in the surface tailings. ERM concluded that the Ontario tests confirmed a use of

0.5-2% binder in surface tailings and did not indicate a need for increased cement content.

ERM encouraged DEQ to allow a range in the binder contents to respond to operational

variability, including varying temperatures, humidity, precipitation, and ore characteristics.

¶42    The effectiveness of Tintina’s on-the-ground adjustments to binder content and total

solid content will be ensured by ongoing monitoring. Tintina’s TOMS Manual outlines

performance parameters for various aspects of CTF operations, including the tailings

delivery and deposition system and the foundation drains system. The Manual shares in

detail the regular monitoring plans for these systems during and after CTF construction.

For example, Tintina will inspect monthly for slope deviation and “cracking, slumping,

erosion, slope failure and any other deformational features in the upstream slope,

downstream slope[,] and embankment crest.” Tintina will inspect for defects in the liner

system bi-monthly. The surface of the deposited tailings will be inspected bi-weekly “for

significant occurrences of water pooling,” and the tailings flow rate and total volume will

be recorded daily. Further, Tintina’s Engineer of Record (sometimes referred to as EOR)

                                             27
will oversee CTF construction and complete an annual inspection of the CTF.9 ERM

identified such “diligent monitoring to confirm closure with design assumptions,

compliance standards, and goals” as a best management practice.

Substantial Evidence of Non-Flowability

¶43    A careful review of the record, summarized in the sections above, reveals substantial

evidence—evidence that a reasonable mind might accept as adequate—to support DEQ’s

conclusion that the surface tailings at the Black Butte Copper Mine would be stable and

non-flowable. See Bachmeier, ¶ 30.

¶44    In a recent decision, we found a DEQ decision supported by substantial evidence

where, in the face of conflicting data in the record, the agency articulated a satisfactory

explanation for its action. In Park Cty. Envtl. Council, DEQ concluded that there would

be no significant environmental impact from groundwater quality issues associated with a

mining company’s proposed exploration. ¶ 39. The district court determined that DEQ’s

analysis fell short in part because the agency selectively relied on borehole data from the

1970s while ignoring other, less optimistic, water quality data collected in the area. Park

Cty. Envtl. Council, ¶ 15. We disagreed with the district court, concluding that DEQ

articulated a satisfactory explanation for why it relied on the borehole data more than data

from other samples—the borehole data provided the most representative samples for

predicting the impact of the proposed drilling based on similar location. Park Cty. Envtl.

9
  Under the MMRA, Tintina was required to designate an Engineer of Record to oversee the
designs and other documents pertaining to the tailings storage facilities; the EOR “may not be an
employee of an operator or permit applicant.” Section 82-4-375(3), MCA. Tintina’s designated
EOR for the Black Butte Project is Ken Brouwer, President of Knight Piésold Consulting.
                                               28
Council, ¶¶ 39-41. We cautioned that the “process of assigning relative weights to

conflicting data for predictive purposes is essentially a technical exercise requiring agency

expertise that should be afforded substantial deference.” Park Cty. Envtl. Council, ¶ 43.

Even though environmental groups pointed to a 2000 report questioning the borehole data,

DEQ provided legitimate scientific reasons for its decision nevertheless to rely on it. Park

Cty. Envtl. Council, ¶¶ 42, 43. We stated that the district court “erred in substituting its

judgment for that of the agency regarding which samples were most predictive of the

environmental impacts.” Park Cty. Envtl. Council, ¶ 43.

¶45    The District Court here similarly erred in substituting its scientific judgment for

DEQ’s.    DEQ’s administrative record contains substantial evidence to support its

conclusion that Tintina’s surface tailings will be non-flowable. First, Tintina proposes to

dewater its tailings into an ultra-thickened paste. The stability of ultra-thickened paste

tailings, without binder, is supported by research in the record and evidence of other

facilities that deposit such tailings and achieve “geotechnical stability” within days.

Second, Tintina proposes to deposit the paste tailings in thin lifts—a practice identified in

the Enviromin Report as allowing sufficient desiccation to provide required stability.

Third, Tintina proposes to add 0.5-2% binder to its surface tailings, an innovative practice

which the Ontario experimenters stated would allow the tailings to consolidate within a

few days and which the working group identified as supportive of structural integrity.

DEQ’s consultant ERM reviewed the Ontario results and confirmed that the proposed

range would be non-flowable. Fourth, Tintina proposes to use a liner and pump system to

                                             29
discharge from the CTF any bleed water and water from rainfall or flooding. Fifth, Tintina

proposes to retain flexibility in the exact binder content to respond to on-the-ground

realities of varying weather and varying total solid content of the tailings. Sixth, and

finally, Tintina will engage in ongoing monitoring to ensure the mass is non-flowable

during operations and at closure. This record evidence, reviewed and analyzed by an

independent review panel and DEQ and its consultants, demonstrates that DEQ evaluated

the science. DEQ’s determination of non-flowability of the surface tailings was not

“apparently random, unreasonable, or seemingly unmotivated based on the existing

record.” Clark Fork II, ¶ 34 (quotations omitted).

¶46   The District Court relied heavily on two selected pieces of the record—the Ontario

lab’s conclusion that a mix with 2% binder “does not achieve final set until approximately

28 days age” and evidence from a study cited in the Enviromin Report that “drying of

deeper layers of paste tailings appears to have been inhibited by addition of a final

cemented-paste layer.” DEQ and Tintina dispute the court’s characterization of these

pieces of the record—arguing 1) that there is a difference between a cemented mass setting

into a non-flowable mass and achieving “final set” and 2) that the study relaying concerns

about drying of deeper layers was conducted by layering cemented paste tailings on top of

uncemented paste tailings, a practice different from the one proposed here. The Dissent

adopts the District Court’s concern, asserting that no record evidence supports DEQ’s

conclusion that the tailings will consolidate in a matter of days. Dissent, ¶ 117. This

misapprehends the evidence DEQ considered.

                                           30
¶47       First, the statement isolated by the District Court regarding inhibition of drying by

the addition of a final cemented-paste layer failed to include the report’s additional

observation from the study “that this [final] layer was only 4 cm thick, which may influence

the observed desiccation and crack formation.” Second, the record substantiates DEQ’s

conclusion about consolidation. Knight Piésold explained that “[t]he tailings are low

permeability with a hydraulic conductivity in the order of 8x10-8 m/sec. The tailings are

highly thickened prior to deposition, and most of the remaining interstitial water will

hydrate the cement and remain trapped in the tailings, with limited bleed water.”10

Moisture in the tailings is important both to prevent dust emissions from the layers and to

ensure the paste-tailings can be pumped to the CTF. As ERM noted in its December 29,

2017 Technical Memorandum, “[p]umpability of the cement paste is critical for the success

of this method.” The purpose of the binder for the surface-placed tailings is to allow the

pumpable paste to achieve a dry, consolidated material, which the testing lab opined would

occur within “a few days.” Third, as explained by the testing lab’s senior engineer, the

cemented-paste tailings, spread in thin layers in the CTF, are “not required to achieve

compressive strength for support.” ERM determined:

          Due to the essentially continuous layered flow of cemented paste into the
          CTF, repeated wetting and drying cycles would be localized in the area and
          few in number. Due to its own mass and confinement of the lower portion,
          significant crack propagation from deterioration is not expected within the
          CTF mass.

10
     Bleed water will be directed to the water reclaim system within the impoundment.
                                                   31
¶48    The District Court’s comparison of a single study using uncemented tailings does

not support a conclusion that would contradict DEQ’s determination, made from

consideration of its experts’ analyses and recommendations. DEQ’s decision to allow

Tintina to layer thin lifts on an average of every seven to fifteen days with 0.5-2% binder

is backed by the evidence relayed above, and DEQ explained its need to weigh competing

concerns such as the potential for oxidation (discussed below) and dust (generated if dry

tailings are exposed for too long). DEQ also weighed the need to be able to pump the

tailings and to allow them to flow into a sloped formation for drainage before becoming

non-flowable.

¶49    The District Court also took issue with Tintina’s failure to test—and DEQ’s failure

to demand a test—of a mixture with 0.5% binder, given that the mine proposes to use a

0.5-2% range of binder. Seizing on this point to conclude that DEQ acted arbitrarily, the

Dissent suggests that the Court’s discussion of the overall structural integrity of the CTF

simply “deflect[s] concerns about the stability of the tailings themselves.” Dissent, ¶ 122.

But a reviewing court must examine “the entirety of DEQ’s rationale.”             Water for

Flathead’s Future, ¶ 24 (citing Park Cty. Envtl. Council, ¶ 18). The whole point of DEQ’s

five-year review process was to assure stability and safety of the tailings storage facility.

The Dissent overlooks three critical points.

¶50    First, cementation of the already thickened (de-watered) paste tailings is just one of

four separate measures that will be used to ensure stability of the tailings. The permit

requires three other levels of protection: (1) containment within two impermeable HDPE

                                               32
liners; (2) surrounded by an embankment; and (3) with three different seepage pumping

systems that will remove excess water from the CTF. These protective measures are

illustrated graphically in the following diagram, found in the administrative record:

                                                                                                                 Piped to Process       N
                                                                                                                 Water Pond
       Pumped paste tails
                     1111*                         1 to 2 degree slope of consolidated tails
                                                         - — - —
                                                                                                     Rock
                                                                                                     Drain
      Basin                                                                                                                / Reclaim
      Drain   .......00   1 mirmr.r.rmnononwnwurvw                                                                           Sump
      System                                                                                                          r/
                                Cemented Tailings Facility                                                                 Water pumped
                                                                                                                           frorn Basin Drain
                                         Paste                                                                             System sump
                                Drainage Layer                                                                             (above liners)

                                                                             I
                                    (rsasteroca)
                          Upper ProtecUve Layer                               - Basin Drain System
                     is,ybgAct                                                                       Water purnped from Geonet
                     Double 100 mil HOPE Liner -                                                     layer if needed (between liners)
                               (red dashedFoe)                               -4 eonet (Pt.7

                          Lowee Cushion layer                                - Foundation drain
                     (subsodu boding mArial)                                   vith outlet pipe      Groundwater and seepage collected
                                                                                 Drainage gravel     and removed from foundation drain
                                  Rock surface
                                                                                                     if needed (below liners)

 DEQEnvironmenT;(5ualty
¶51     No one—not MTU, not the District Court, and not the Dissent—takes issue with

any of the other three measures. There is record support that even the embankment and

HDPE liners together, neither of which the District Court or MTU faulted—would be

sufficient to make the storage facility safe and stable. The Dissent barely mentions these

features, except to suggest that “structural integrity” does not ameliorate need for “the

stability of the tailings themselves.” Dissent, ¶ 122. But the record is replete with studies

and data about achieving a non-flowable mass for the tailings stored above ground.

Cementing the paste tailings provides an additional protective feature, which—after

                                                                        33
extensive evaluation—Enviromin reported would meet “the highest level of tailings safety

management” and posed an extremely low-to-no risk of catastrophic failure.

¶52    Second, in choosing a range of binder content for the CTF, DEQ did not pick an

arbitrary number. The lower end of the range, 0.5%, was not invented by Tintina to save

costs or drawn at random by the agency without basis. The Ontario lab tested a range of

total solid content and a range of cement binder (0%, 2%, and 4%) that encapsulates the

complete range DEQ ultimately authorized. Results from those experiments were analyzed

by Tintina, by Tintina’s consultants, and by DEQ’s consultant. All agreed there was no

conclusive evidence that 4% binder was needed for surface tailings, as there was no need

for unconfined compressive strength in the surface tailings like there was in the backfill

tailings. All agreed that a lesser percentage of binder, in combination with other aspects

of the CTF’s design and operational flexibility, would be beneficial in the safety and

stability of the CTF. DEQ and Tintina cite to the fact that the experiments demonstrated

that a high total solid content and 0% binder might slump less than a cylinder with low

solid content and 4% binder. DEQ adopted the precise range recommended by the

scientific laboratory that conducted the full range of testing—and only after having its own

consultant ERM conduct further analysis, which concluded that “the testing regimen

supports the selected cement content levels and does not indicate a need for or benefit from

increased cement contents.” As noted earlier, ERM encouraged DEQ to allow a range to

respond to operational variability, including varying temperatures, humidity, precipitation,

and ore characteristics. By following this recommendation, DEQ did not act arbitrarily.

                                            34
The District Court did not explain, and MTU did not substantiate in the record, how

additional testing could have added to the scientific analysis resulting from the 0 to 4%

range of binder tested or how DEQ’s failure to require testing of yet another variant within

that range rendered its decision arbitrary in the face of all the scientific data and expert

recommendations it considered. Focusing “on the validity and appropriateness of the

administrative decision-making process,” Clark Fork I, ¶ 47, the record makes clear that

DEQ did not “rel[y] on incorrect assumptions or data,” Envtl. Def. Ctr. v. Bureau of Ocean

Energy Mgmt., 36 F.4th 850, 872 (9th Cir. 2022), but on testing and recommendations

made from expert analysis. Drawing conclusions from such analysis “is essentially a

technical exercise requiring agency expertise that should be afforded substantial

deference,” Park Cty. Envtl. Council, ¶ 43, so as to avoid “interfering with the

administrative authority over the decision itself,” Clark Fork I, ¶ 47.11

¶53    Third, neither core sample cylinder testing nor examination of other studies could

replicate conditions in the field. Importantly, as ERM observed, continuing further testing

11
  The Ninth Circuit cases cited by the Dissent are readily distinguishable. In Envtl. Def. Ctr., for
example, the U.S. Department of the Interior granted offshore well stimulation treatment (fracking)
permits without conducting an EIS on the basis of its unfounded assumption that such treatments
“would happen so infrequently that any adverse environmental effects would be insignificant.”
36 F.4th at 873. The record showed, however, that the agency had no formal data collection system
in place to track such activity and had in fact approved at least 51 permits “without conducting
[any] environmental review” and acknowledged that it “[could not] be sure just how often fracking
has been allowed.” 36 F.4th at 873. Even there, the court determined that the “gaps and errors
underlying the agencies’ assumption . . . would not be as critical if this assumption was not central
to the agencies’ finding of no significant impact.” 36 F.4th at 874. And the defect in Lands
Council v. Powell was—similar to our ruling in Mont. Env’l Info. Ctr. v. Westmoreland Rosebud
Mining, LLC, 2023 MT 224, ¶¶ 61-70, 414 Mont. 80, ___ P.3d___,—that the agency had failed to
properly evaluate cumulative effects of the proposed project and ignored key variables in that
analysis. 395 F.3d 1019, 1027-28, 1031-32 (9th Cir. 2005).
                                                35
“follows prudent practice” and will “allow[] changes to accommodate varying ore and

tailings characteristics, as well as changes in binder and admixture sources and

requirements.”   That is why DEQ required continued monitoring and assessment to

determine the right binder content level. This “adaptive management” flexibility is

expressly within the contemplation of the MMRA. See § 82-4-301(2)(b), MCA (calling

for consideration of “site-specific conditions and concerns” in specifications for tailings

storage facilities); § 82-4-301(2)(c), MCA (allowing “adaptive management using

evolving best engineering practices based on the recommendations of qualified,

experienced engineers”); § 82-4-301(3), MCA (recognizing that “tailings storage facilities

must vary according” to “geological, topographical, climatic, biological, and sociological

conditions” applicable to each facility).

¶54    DEQ’s ultimate conclusion that, based on all relevant evidence and its

acknowledgment of a certain amount of scientific uncertainty, Tintina’s proposed range of

binder content, in conjunction with adaptive management, would provide for a

non-flowable mass was reasonable, had substantial support in the record, and accords with

the adaptive vision set forth in MMRA. See §§ 82-4-301(2)(c), -301(3), MCA.

Oxidation

¶55    The District Court concluded that DEQ “did not rationally evaluate the potential

that oxidation could undermine the stability of the tailings facility,” despite DEQ’s

admission “that exposure to oxygen and water would cause the tailings to oxidize which—

if widespread—could cause Tintina’s solid tailings to deteriorate and lose their structure.”

                                            36
The District Court relied on evidence in Enviromin’s Surface-Placed Cemented Paste

Tailings Report, which indicated “the potential for oxidation pathways into lower layers of

surface-disposed paste tailings.” The court reasoned that in the face of evidence that

oxygen could permeate below the tailings surface and that cracking could be exacerbated

by layering cemented tailings over wet tailings, DEQ’s approval of Tintina’s plan to

deposit frequent lifts to prevent oxidation was arbitrary.

¶56    DEQ and Tintina again argue that the court relied on selective record evidence and

misread that evidence.     MTU responds that the court correctly identified that DEQ

improperly disregarded “alarming results of the only tests Tintina performed to examine

the oxidation potential of the company’s tailings, instead relying on an insufficiently

supported assertion that, because each tailings layer would be quickly layered over and

therefore remain insulated from oxygen and water, widespread oxidation would not occur.”

(Emphasis in original.)

¶57    MTU refers to the Humidity Cell Tests (HCTs) conducted by Tintina. Tintina

conducted the HCTs to determine whether tailings in the CTF could oxidize when exposed

to air and water and release acid harmful to the environment. Experimenters prepared and

tested samples of tailings material sourced from the proposed mine site, added 2% and 4%

binder to some, and formed the samples into columns. Experimenters then aerated the

samples “with alternating cycles of humid and dry air, followed by weekly flushing with a

relatively large volume of water.” The column then was allowed to drain, and the cycle

repeated weekly. Samples—with and without binder—produced acid quickly under the

                                             37
testing conditions and eventually disaggregated. DEQ described the results as indicating

that “the cemented paste tailings could potentially oxidize if exposed to air and water and

release acid.”

¶58    DEQ reasoned, however, that the on-the-ground conditions at the CTF would be

less aggressive than the HCTs. In reaching this determination, DEQ relied on Enviromin’s

analysis of the HCT data, which stated:

       It is likely that these HCTs conservatively represent the potential rates of
       oxidation for cemented paste tailings, because tests were run on small,
       laterally-unconfined cylinders with a higher surface area to mass ratio than
       would exist within the more massive CTF deposits. Furthermore, it is widely
       accepted that sulfide oxidation in an HCT, which optimizes and accelerates
       the intrinsic oxidation rate, is typically greater than that under field
       conditions. Therefore, the disaggregation observed in these tests is
       considered conservative with respect to ultimate field conditions. The results
       of early weeks of testing, prior to excessive disaggregation, are, thus, more
       relevant to geochemistry of paste tailings in the CTF.

DEQ’s consultant ERM acknowledged that the HCTs demonstrated that added binder “is

not sufficient to neutralize the sulfide in the tailings” but emphasized that the binder was

not added with the intent to do so. The binder, instead, was added to change the physical

properties of the tailings to a stable, non-flowable material with low hydraulic

conductivities.   DEQ also relied on Enviromin’s Report on Baseline Environmental

Evaluation of Waste Rock and Tailings, which concluded that the HCTs “demonstrate that

paste-amended treatments have lower potential for acid, sulfate, and metal release than

HCTs of raw tailings.”

¶59    DEQ also considered evidence beyond the HCTs and analyses of the HCTs. For

example, DEQ considered that the low permeability of ultra-thickened paste tailings

                                            38
restricts the flow of oxygen through the material and limits the potential for sulfide

minerals to oxidize and produce acid. The effectiveness of low permeability in addressing

oxidation—even in a mine with high-sulfide tailings—was supported by findings in

Enviromin’s Report on Surface-Placed Cemented Paste Tailings. Additionally, DEQ

considered Knight Piésold’s reporting, which stated that the addition of binders such as

slag and fly ash has “improved resistance to sulfate attack over cement.” DEQ also

considered Tintina’s proposed measures to optimize cement and binder additions over time

and to use a lined facility to collect and treat water. Both measures were supported by

Knight Piésold and Enviromin to address potential oxidation. Finally, DEQ considered

Tintina’s proposal to cover lifts in a timely manner to minimize oxidation of the uppermost

exposed lift, a practice recommended by Enviromin. The Enviromin Report shared that

the Bulyanhulu Mine’s “continuous application of lifts on a 5-day depositions cycle

prevented oxidative weathering of exposed surfaces.” Enviromin’s April 2017 report

recommended “that the cement pasted material be covered in a timely manner (on the scale

of weeks) to minimize oxidation, acidity, and leaching of metals.” (Emphasis added.)

Enviromin also observed that “[d]espite the exposure to air, the low permeability of paste

tailings limits oxidative weathering.” Pointing to a 2008 study, it reported “that while

seepage from surface-placed paste tailings is extremely unlikely, because they have very

low hydraulic conductivity by design, any potential seepage to groundwater could be

mitigated with the use of clay or synthetic liners.” The report concluded:

      Due to the potential for release of various metals at different times in the
      predicted weathering process, Tintina proposes to encapsulate all waste rock

                                            39
       in paste tailings within the double-lined CTF impoundment. Furthermore,
       Tintina proposes to collect all seepage from the waste rock stockpile, the
       CTF, and the underground workings for treatment prior to discharge via
       underground infiltration galleries. With implementation of these engineering
       controls, potential for negative impacts to surface and groundwater is low.

¶60    The District Court did not consider, and the Dissent brushes past, the double HDPE

liners that will encapsulate the CTF and the seepage-collection systems—the very

mitigation to which the science points. Enviromin’s analysis further supported Tintina’s

use of covering the final lift with a third liner and soil and vegetation to eliminate long-term

exposure of lifts.

¶61    The District Court disagreed with the reasonableness of DEQ’s review of oxidation

by emphasizing evidence from a study cited by the Enviromin Report that stated that

layering new lifts over wet tailings created the potential for oxidation pathways and

cracking of lower layers. The full picture from Enviromin’s report, however, is not as clear

as the court states. The report states that researchers initially conducted thirty-week layered

column leaching tests using varying proportions of cement in sulfidic paste tailings. The

initial study concluded that modest amounts of cement presented an effective way to

stabilize sulfide minerals in a surface placement scenario. The same researchers later

published results from a long-term study of lab-scale cemented paste tailings placed within

layers of paste tailings. They observed “that the pH did not drop despite the development

of preferential oxidation paths and persistent desiccation cracking.” DEQ’s commissioned

technical memorandum reflected this understanding, stating that “[n]ot all cracking is

deleterious, as some reaction products simply fill the cracks, retaining hydrologic and even

structural integrity.” The District Court, citing the possible oxidation paths and cracking,
                                              40
failed to acknowledge that DEQ considered them and rationally relied on evidence of their

non-deleterious nature.

¶62    Finally, both the District Court and the Dissent single out the Bulyanhulu Mine

among the numerous studies cited in the Enviromin Report on Surface-Placed Cemented

Paste Tailings, suggesting that DEQ arbitrarily disregarded Bulyanhulu’s application of

lifts on a five-day cycle. It bears emphasis that the Bulyanhulu Mine uses no binder, just

paste tailings. Enviromin’s detailed study of the core samples taken here recommended

covering the lifts “on the scale of weeks.” The Dissent criticizes what it views as DEQ’s

non-specific requirement for “thin” lifts, faulting the agency for not saying how thin is

“thin.” Dissent, ¶ 120. The Bulyanhulu study defined “thin” at that site as 30cm, which

was based on site-specific conditions.     As mentioned before, the record shows the

importance of such site-specific considerations, including ore and tailings characteristics

and the wide temperature fluctuations existing at the Black Butte location. Further, based

in part on its review of the Bulyanhulu Mine, Enviromin recommended placing the

cemented paste tailings within a lined surface facility “to offer the best-available

environmental controls.” DEQ adopted this recommendation. Finally, MTU points to

nowhere in its comments that it suggested DEQ must put specific parameters on the “level

of thickness” of the lifts. For the Court to do so now would go beyond the “intense

scrutiny” we have eschewed in reviewing an agency’s determination of such matters.

Mont. Wildlife Fed’n, ¶ 43; Clark Fork I, ¶ 47.

                                            41
¶63    Given the above evidence, we disagree with the District Court’s characterization of

DEQ’s review of the issue of oxidation as random or unreasonable. Again, DEQ balanced

various concerns—ensuring that tailings would have time to set into a non-flowable mass

and covering tailings in a timely manner to prevent exposure and oxidation.             DEQ

identified that the following aspects of Tintina’s proposed CTF addressed oxidation

concerns: 1) deposition of tailings as an ultra-thickened paste with low permeability;

2) layering of successive lifts within seven to thirty days before extensive oxidation could

occur; 3) ensuring no tailings were left exposed at closure; 4) using a lined facility with

drains and pumps to treat discharged water; and 5) utilizing flexibility in binder type and

amount and ongoing monitoring to address issues that arise. Evidence of a study of

non-deleterious cracking—which DEQ reviewed—does not negate the reasonableness of

DEQ’s decision. The record demonstrates that DEQ rationally evaluated the potential for

oxidation in the tailings and contains sufficient evidence to ensure the CTF’s safety and

stability.

Liquefaction

¶64    The District Court concluded that DEQ also failed to examine rationally the

potential for tailings liquefaction. Liquefaction occurs “when an otherwise solid material,

usually partially saturated with water, loses strength and flows like a liquid” in response to

a seismic event, mine blasting, or slope instability. In reaching its conclusion, the court

relied on Enviromin’s summary of a review of a British Columbia tailings facility that

indicated “the most likely mechanism for failure would be liquefaction of the pasted

                                             42
tailings as a result of seismic activity.” The court also relied on Enviromin’s summary of

research conducted in 2002 to study “the minimum proportion of cement required to

prevent liquefaction of cemented-paste tailings backfill at the Neves Corvo Mine in

Portugal.” That study “concluded that the minimum content must be greater than 1% to

prevent liquefaction.” The court determined that Tintina’s proposed use of as little as 0.5%

binder in the surface tailings in light of this evidence rendered DEQ’s confidence in the

safety and stability of the CTF arbitrary.

¶65    DEQ and Tintina argue that DEQ evaluated and correctly approved Tintina’s

proposal to address the risk of liquefaction of the surface tailings. They point to DEQ’s

reliance on dewatered and non-flowable cemented tailings, which DEQ determined would

result in a very low permeability, “preclud[ing] liquefaction.” DEQ and Tintina also argue

that DEQ further considered Tintina’s plans to address any excess water with its drain and

pump system. DEQ and Tintina contend once again that the record evidence relied on by

the District Court was inapposite and that the District Court stepped outside its role in

reviewing a DEQ permitting decision.

¶66    MTU responds that the District Court correctly concluded that DEQ omitted a

meaningful analysis of the potential for liquefaction in the face of the cited concerns in the

record. MTU further argues that the dewatering method that DEQ and Tintina rely on to

address liquefaction is a standard practice for all paste-tailings facilities where liquefaction

nevertheless remains a demonstrated concern.

                                              43
¶67    Our review of the record supports DEQ’s and Tintina’s contentions that DEQ

reviewed the issue of liquefaction and had sufficient information to determine that the CTF

would be safe and stable.       DEQ reasoned that the surface tailings “are a stable,

non-flowable (after placement), low-strength solid when consolidated,” which “precludes

the risk of liquefaction or widespread release of tailings in response to impoundment failure

or seismic events.” Contrary to the Dissent’s criticism of this conclusion as lacking

“scientific references,” Dissent, ¶ 135, DEQ’s consultant ERM evaluated the

“still-innovative technique” of mixing cement into tailings prior to surface storage, as

opposed to dewatering and densification to increase the mechanical qualities of tailings.

ERM determined: “The mechanical quality improvements essentially include increasing

cohesion and friction angle with a commensurate increase in resistance to seismicity, with

or without impounding embankments.” It continued,

       With the adoption of common concrete mixing equipment to the tailings
       handling process, the proposed CTF would further extend the reliability and
       robust nature of both operational placement and long-term storage of the
       tailings. Rather than storing a mass that may be subject to liquefaction, the
       CTF would hold a solid cement mass.

       During operation, the susceptibility of the placed and set cement to both
       water infiltration and release of contained moisture would be lower than
       uncemented tailings. Since the contained moisture potentially would carry
       metals and salts, the cementation provides a desirable environmental benefit
       in chemical as well as mechanical terms.

Further noting the CTF’s double-liner system, ERM concluded that “[t]hese robust

containment systems further protect the environment from a solid mass of concrete, which

would have minimal water available for release.”

                                             44
¶68    Much of the above-described aspects of the CTF and underlying research support

DEQ’s determination, such as the plans to dewater the tailings, the plans to use a drain and

pump system to remove excess water (which the District Court failed to acknowledge), and

the low permeability of the surface tailings, which “restricts the flow of water and

movement of oxygen through the tailings and precludes liquefaction during earthquakes

because there is not sufficient water stored between tailings grains to allow the material to

move as a fluid in response to sudden agitation.”

¶69    Alerting the court to the mere presence of conflicting information in the record—

selected from case studies of different mines—is not enough to show that DEQ failed to

take a hard look at liquefaction or that there is insufficient evidence of the CTF’s safety

and stability. What is more, DEQ and Tintina point to compelling differences from the

evidence cited by the court. For example, the British Columbia mine used paste tailings

without binder, and the Neves Corvo Mine study recommending a binder content greater

than 1% examined cemented paste tailings deposited underground as backfill.

¶70    Though MTU cites the Neves Corvo study to support its argument that DEQ

disregarded the potential for liquefaction, a closer look reveals the study’s usefulness and

limitations in the analysis here. The study was conducted in situ during active mining

operations to make recommendations regarding cement content for paste backfill in the

secondary stopes at the Neves Corvo mine to avoid liquefaction. K. Been, E. T. Brown &

N. Hepworth, Liquefaction potential of paste fill at Neves Corvo mine, Portugal, Mining

Technology, 111:1, 47-58 (2002) https://doi.org/10.1179/mnt.2002.111.1.47. The study

                                             45
looked at paste fill placed into an underground stope—where it was subject to higher

stresses than Tintina’s above-ground CTF would be. To conduct the study, researchers

created a trial stope away from active mining operations. After placing tailings paste with

varying levels of cement binder in the trial stope and allowing it to cure for several months,

the authors drilled three boreholes to collect samples. One of the three was located near the

rear of the stope, where ponding of water had occurred; the samples from that borehole

were noted to have been affected more as a result. It is unclear from the report the extent

to which the paste fill was first thickened by dewatering, but the study noted that, without

the cement binder, the paste fill “would be classified as a non-plastic, uniformly graded

silt.”12 The authors recommended a minimum of 1% cement in the backfill—one-quarter

of what Tintina will use in the cemented tailings deposited in the Black Butte backfill. The

authors suggested it would be prudent to use “a higher (e.g. 2%)” content if the stope had

a high probability of a trigger event and the consequences of liquefaction would be serious.

Finally, they noted that “procedures for the placement of paste should ensure that any

excess water is diverted away from the backfilling area.” To the extent the takeaways from

this study are useful, Tintina incorporated (and DEQ adopted) its salient recommendations

into the CTF design—using a higher binder for the backfill and including three different

seepage pumping systems that will remove excess water from the CTF.

12
  This is in apparent contrast to Tintina’s plan to use ultra-thickened paste with a high solid
content.
                                              46
¶71    In sum, DEQ articulated a satisfactory explanation for its determination that

Tintina’s proposal adequately safeguarded against the risk of liquefaction of the cemented

paste tailings. See Clark Fork I, ¶ 47.

Independent Review Panel

¶72    As observed, the Legislature’s 2015 MMRA revisions added specific requirements

for tailings storage facilities. Applicants for mining permits meet the requirement of “a

plan . . . sufficient to ensure” the safety and stability of a tailings storage facility by

submission of: 1) a design document; 2) a report by an IRP; and 3) a TOMS manual.

Section 82-4-335(4)(l), MCA. The IRP requirements are laid out in § 82-4-377, MCA.

The panel consists of three “independent review engineers” selected by the permit

applicant and approved by DEQ. Section 82-4-377(2), MCA. Panelists may not be an

employee of the permit applicant and may not be the design consultant, the engineer of

record, or the constructor. Section 82-4-377(3), MCA. Representatives of DEQ and the

permit applicant may—and the engineer of record (EOR) shall—participate on the panel,

but they are not members of the panel. Sections 82-4-377(5), -377(6), MCA. The IRP

“shall review the design document required by 82-4-376 [requiring 31 descriptions and

analyses].” Section 82-4-377(1), MCA.

¶73    Subsections 8, 9, and 10 of § 82-4-377, MCA, explain the IRP’s review process:

       (8) The panel shall review the design document, underlying analysis, and
       assumptions for consistency with [MMRA]. The panel shall assess the
       practicable application of current technology in the proposed design.

       (9) The panel shall submit its review and any recommended modifications to
       the operator or permit applicant and the department. The panel’s

                                            47
       determination is conclusive. The report must be signed by each panel
       member.

       (10) The engineer of record shall modify the design document to address the
       recommendations of the panel and shall certify the completed design
       document. The operator or permit applicant shall submit the final design
       document to the department pursuant to 82-4-376.

Section 82-4-377(8-10), MCA.

¶74    The District Court concluded that Tintina and DEQ failed to comply with IRP

requirements because the panel never reviewed a complete design document for the

proposed CTF prior to certifying its review to DEQ on July 28, 2017. The court found that

the panel issued its certification before reviewing three required components of the design

document—a seismic evaluation, a dam breach assessment, and a construction

management plan. And although the court acknowledged that the panel may have received

a dam breach assessment in August 2017, the court determined that any possible review at

that point was untimely given that it occurred after the panel’s July certification.

¶75    DEQ and Tintina argue that the panel: 1) reviewed the seismic evaluation that

Tintina included in its initial design and the additional analysis Tintina included in its

revised design, rendering the court’s finding otherwise clearly erroneous; 2) reviewed the

dam breach assessment on August 11, 2017, and determined no further reporting was

needed; and 3) reviewed the substantial elements of a construction management plan

despite the fact that those elements were not contained in a stand-alone document with the

title “Construction Management Plan.” DEQ and Tintina also assert that the IRP was not

required to review a complete design document again after Tintina addressed its

                                             48
recommended modifications. MTU responds that, regardless of the number of times that

MMRA contemplates an IRP reviewing a design document, the IRP here never once

reviewed a design document containing the three required components.

¶76    As an initial point, we agree with the District Court that the plain language of

MMRA requires an IRP to examine a design document containing all elements described

in § 82-4-376, MCA. See § 82-4-377(1), MCA (“An independent review panel shall review

the design document required by 82-4-376”); § 82-4-377(8), MCA (“The panel shall

review the design document . . . for consistency with [MMRA].”). It makes little sense to

allow an applicant to submit to the IRP a design document wholly missing such crucial

information as a dam breach analysis, allow the panel to state that such information is

missing in its review, and then allow the applicant to add the analysis and submit such

revisions to the DEQ without the panel seeing it. See Hillcrest Natural Area Found. v.

Mont. Dep’t of Envtl. Quality, 2022 MT 240, ¶ 47, 411 Mont. 30, 521 P.3d 766 (statutory

construction should not lead to absurd results if a reasonable interpretation can avoid it).

¶77    Upon review of the record here, however, we agree with DEQ and Tintina that the

IRP reviewed all substantive information required by MMRA. We do not hold, as the

Dissent claims, that the applicant be allowed “to submit required information directly to

the DEQ without the IRP ever seeing it.” Dissent, ¶ 141. First, the record demonstrates

that Tintina included some seismic analysis in its application, which the IRP reviewed

before it issued its July 28, 2017 report. See § 82-4-376(2)(i-m), MCA. Knight Piésold

submitted its first report in October 2015 and revised it eight times before its final

                                             49
submission in early July 2017, prior to the IRP’s final report. Noting the MMRA’s

requirement that new tailings dams be able to withstand the greater of either the 1-in-

10,000-year earthquake event or the Maximum Credible Earthquake Event, (MCE), Knight

Piésold reported that the Maximum Design Earthquake (MDE) would be updated “if

required” following assessment of the MCE for the Project “in future design phases.”

Knight Piésold’s extensive July 2017 report, which covered all aspects of the tailings

storage facility, did include the results of its CTF stability analyses for both “static” and

“seismic” conditions, both during operations and post-closure. The report also contained,

among other things, the firm’s analyses of the facility embankment, seepage control

system, construction, process water pond, and operations and monitoring. Pending the

IRP’s review of these designs, the firm did not complete a dam breach inundation study at

that time but would await the IRP’s recommendations.

¶78    In its July 28, 2017 report, the IRP gave the feedback that “The MCE for the site

must still be developed as the design moves forward.” An August 9, 2017 letter from

Knight Piésold to DEQ indicated that the IRP had “recommended that additional detail be

provided on fault locations and confirmation that these faults are inactive during the

detailed design phase.” The letter assured that the analysis requested by the IRP was in

progress and that it “is expected to confirm that the 1 in 10,000 year probabilistic event is

the most appropriate MCE for the site.” At an August 11, 2017 conference call with the

EOR and DEQ, the IRP confirmed that it was satisfied with Tintina’s materials and stated

that it would not issue further recommendations. Tintina included the promised additional

                                             50
seismic analysis in its revised September 12, 2017 design document to DEQ. The site-

specific study analyzed the issue of faults but identified no concerns.

¶79    Second, the record demonstrates that the IRP reviewed a dam breach analysis.

Tintina’s EOR noted that a dam breach study “will be completed as part of future design

phases . . . if required pending the review of these designs by the independent engineering

review panel.” See § 82-4-376(n), MCA. After its review of the design document, the IRP

recommended a dam breach analysis be conducted. Knight Piésold conducted the dam

breach analysis, and Tintina provided it to the IRP on August 11, 2017. The study

concluded that the probability of failure for the various hazards was either not credible or

very low. During the August 11, 2017 meeting, the IRP stated that it saw no need to modify

its July 28, 2017 report in support of the permit. Tintina included the dam breach analysis

results in its September 12, 2017 revised application to DEQ.

¶80    Third and finally, the record demonstrates that the IRP reviewed the substantial

elements of Tintina’s construction management plan. MMRA requires that the design

document include:

       a construction management plan that includes, at a minimum, parameters and
       levels of acceptability to be monitored during construction for quality control
       and quality assurance purposes. The frequency of sampling, the amount of
       oversight, the qualifications of the oversight personnel, and the role of the
       panel during and after construction must be specified and agreed to by the
       panel.

Section 82-4-376(2), MCA. As Tintina points out, various sections of its TOMS manual

meet this requirement. Section 4 describes the protocols for waste and water management

facilities required during construction, including a detailed description and numerous

                                             51
referenced schematics of the CTF and its two-stage construction. Section 5 details seven

quantitative performance parameters for monitoring during construction and operation,

which address the CTF embankment; the CTF basin drain and water reclaim systems; the

CTF tailings delivery and deposition system; the CTF foundation drain; the process water

pond; the non-contact water reservoir; and the mine site water balance. Each of these seven

subsections includes details about the frequency of sampling during construction,

instrumentation, surveillance and maintenance, and monitoring inspections. The TOMS

manual also states that Tintina’s third-party EOR and a panel of three independent tailings

engineers would oversee the design, construction, operation, and closure of the CTF, and

Tintina provided their qualifications. Though MTU argues that the TOMS manual is a

separate statutory requirement, the statute does not mandate duplication if the manual

contains the same construction management information. Unlike the defect we found in

Citizens for Responsible Dev. v. Bd. of County Comm’rs, 2009 MT 182, ¶ 20, 351 Mont.

40, 208 P.3d 876, the elements of the construction management plan were not “buried in

documents created primarily for other purposes” (emphasis added) but were prominently

set forth in the TOMS manual—one of the required elements of Tintina’s application under

the MMRA and created for the very purpose the construction management plan is designed

to address.   That the TOMS manual rolled the construction management into its

comprehensive operations plan does not render the submission defective under the MMRA.

¶81    We conclude that the iterative process between the IRP, the Engineer of Record,

Tintina, and DEQ was acceptable under MMRA’s IRP requirements.               The MMRA

                                            52
contemplates that the independent review will lead to a panel’s recommendations, and it

obligates the Engineer of Record to modify the design document to address those

recommendations. Section 82-4-377(9-10), MCA. The statute does not mandate that the

IRP review the EOR’s modifications in response to the panel’s recommendation. See

§ 82-4-377(1), MCA. Here, the panel’s July 28, 2017 report expressly acknowledged

“ongoing studies” yet to be carried to completion. The IRP “commended” Tintina for

engaging it early in the project and anticipated the panel’s continued participation.13 MTU

points to no substantive difference that would have resulted had the IRP reviewed the dam

breach analysis in its first review or had Tintina resubmitted to the IRP the full seismic

analysis it completed after receiving and following the IRP’s recommendations. The panel

reviewed all required analyses and documentation, and the EOR modified Tintina’s design

document in accordance with its recommendations.

¶82    The above record evidence demonstrates that the panel complied with MMRA’s

requirement of independent review of a proposed tailings storage facility.

                                            .   .   .

¶83    DEQ satisfied MMRA and MEPA in approving Tintina’s proposed CTF and the

District Court erred in concluding otherwise. MMRA requires the following three items

to ensure the safety and stability of a tailings storage facility before DEQ may issue a draft

permit: a design document, a report by an independent panel, and a TOMS manual. Section

13
  The Dissent’s suggestion that an Independent Review Panel could “become invested in its initial
decision” and less willing to make additional recommendations, Dissent, ¶ 147, is unmoored from
this record, purely speculative, and merits no further discussion.
                                                 53
82-4-335(4)(l), MCA. Tintina provided all three. DEQ took a hard look at environmental

impacts during its MEPA review, engaging independent consultation along with its own

scientific research and study, and articulated its rationales when it rendered the final

determination. The District Court’s reliance on select evidence in the voluminous record

fails to demonstrate a clear error of DEQ’s judgment in evaluating the proposal. The

agency’s decision was “scientifically driven,” informed by “substantial agency expertise,”

and is entitled to considerable deference. MEIC, ¶ 20. The record supports DEQ’s

reasoned decision to approve the safety and stability of Tintina’s proposed CTF. Clark

Fork I, ¶¶ 21, 47.

¶84    Issue Two: Did DEQ satisfy MEPA by rationally evaluating the environmental
       impact of the mine’s total nitrogen discharges into Sheep Creek?

¶85    Sheep Creek is subject to a seasonal nitrogen limit in effect from July 1 to

September 30 each year. The limit derives from DEQ’s non-degradation analysis, which

protects high quality waters such as Sheep Creek. DEQ determined the non-degradation

nitrogen limit for Sheep Creek to be 0.09 milligrams per liter (mg/L) during that three-

month period. In the MPDES (water quality) permit, DEQ observed that:

       for Sheep Creek, the nitrogen standards are very low and the nonsignificance
       criterion is so low that the stream is already at or above this level a significant
       portion of the time. There is not assimilative capacity to allow a mixing zone.

¶86    Tintina proposes to pump groundwater from its underground mine to a water

treatment plant, where it would undergo reverse osmosis treatment. Some treated water

would be used in mining operations; the majority would be discharged to an underground

infiltration gallery (UIG). The UIG consists of excavated trenches and then an alluvial

                                               54
aquifer (shallow sand and gravel deposits along Sheep Creek), before discharging to Sheep

Creek. Tintina’s discharge to the UIG is estimated to contain an average of 0.32 mg/L

nitrogen and a maximum of 0.57 mg/L. After dilution with ground and surface water, the

maximum nitrogen level in the immediate area where the discharged water enters Sheep

Creek is estimated to be less than 0.12mg/L, which is within the standards in place from

October 1 to June 29. As part of its review, DEQ required Tintina to cease all discharge

“on or before July 1” and instead hold the pumped groundwater in a storage pond until

after September 30.14

¶87    The District Court held that DEQ violated MEPA in its review of the potential for

nitrogen pollution from the groundwater that Tintina proposes to pump from its

underground mine and discharge into Sheep Creek. The court took issue with Tintina’s

proposal to discharge water with nitrogen concentrations of up to 0.57 mg/L via the UIG

up until July 1 each year to avoid violating the seasonal nitrogen limit in place July 1

through September 30. Because the record indicated that there could be a lag time of up

to a few months between initial discharge and the discharge reaching Sheep Creek, the

court found that DEQ’s approval of continued initial discharge up until July 1 was

irrational, reasoning that pre-June 30 discharge may enter Sheep Creek after July 1 and

violate the seasonal limit.

14
   DEQ anticipates that Tintina’s discharge of treated water may also impact so-called “Coon
Creek,” which is subject to the same non-degradation limit for total nitrogen as Sheep Creek. Our
discussion applies to both.
                                              55
¶88    DEQ and Tintina argue that the court’s holding was erroneous, given record

evidence of DEQ’s consideration and rationale for its decision. MTU responds that DEQ’s

decision conflicted with the agency’s own review of the relevant science because it

acknowledged that, even after mixing with groundwater, discharges would exceed the

non-degradation standard and could enter Sheep Creek with such excesses between July

and the end of September. It maintains that DEQ thus arbitrarily overlooked the water

migrating from the UIG into Sheep Creek. Importantly, MTU does not challenge this on a

substantive basis—such a challenge properly would be brought to Tintina’s MPDES permit

under the Water Quality Act, which MTU does not contest.

       MEPA is “essentially procedural.” Like its federal counterpart, “it does not
       demand that an agency make particular substantive decisions.” Rather, it
       requires “an agency to review projects, programs, legislation, and other
       major actions of state government significantly affecting the quality of the
       human environment in order to make informed decisions.”

Mont. Wildlife Fed’n, ¶ 32 (quoting Ravalli County Fish & Game Assn., 273 Mont. 371,

377-78, 903 P.2d 1362, 1367 (1995)). In reviewing DEQ’s MEPA analysis, our “focus is

on the administrative decision-making process rather than the decision itself.” Park Cty.

Envtl. Council, ¶18.

¶89    In the Final EIS, DEQ addressed a comment that it had failed to evaluate the lag

time such that “Tintina could violate the stricter summer nitrate standards.”         DEQ

explained that, although water released via the UIG before July 1 “might occasionally carry

nitrogen at concentrations above the non-degradation effluent limits,” it would be subject

to attenuation “while filtrating through alluvial sands and wetland areas[.]” DEQ relied on

                                            56
cited sources in support of this assessment and noted its preference for “a slow rate of

nitrogen-containing-groundwater migration from the UIG to the creek, making the

seasonal discharge limits important.” The MPDES Permit stated that the data used to

calculate the interquartile range (IQR) of the receiving water’s total nitrogen concentration

were collected during the July to September season in which the water quality standards

apply. It explained,

       The calculations performed by DEQ will protect the stream by creating a
       margin of safety in the limits to account for all of the variability in the creeks,
       ground water, and the discharge.

¶90    The District Court found speculative DEQ’s determination that the longer the

discharged water remains underground, the more nitrogen will be attenuated, stating that it

lacked “any supporting analysis.” But the agency cited scientific literature documenting

this finding, and at least two such studies on which it relied are in the administrative record.

The Final EIS emphasized that:

       the slow rate of water infiltration is not a good indicator that total nitrogen
       could take months to reach surface water, but an indicator that total nitrogen
       would have time to attenuate in the soils and may never reach the creek. The
       well-established science behind total nitrogen in soils is that total nitrogen is
       rapidly taken up or denitrified to harmless nitrogen gas by microbes. For
       total nitrogen, DEQ would actually prefer slow infiltration and long detention
       time.

Although MTU expresses concern about the effectiveness of attenuation, it does not point

to any contrary evidence in the record sufficient to meet its MEPA burden to establish that

the agency failed to “examine the relevant data [or] articulate a satisfactory explanation for

its action, including a rational connection between the facts found and the choice made.”

                                               57
Clark Fork I, ¶ 47. “The [party] challenging the [agency’s] decision has the burden of

proving the claim by clear and convincing evidence contained in the record.” Section

75-1-201(6)(a)(i), MCA. See also Water for Flathead’s Future, ¶ 12. Though not an

argument raised by MTU, the Dissent speculates that DEQ unreasonably relied on

attenuation studies that occurred in geographic areas different from Montana. But both

attenuation studies offered strong support for their conclusions, one stating that “a

remarkably small area of wetland sediment can strongly influence water quality”15 and the

other finding “small seepage wetlands” in stream headwaters to be “very effective at

removing nitrogen loads.”16

¶91    Coming to its own conclusions from the data, the Dissent also questions DEQ’s

reliance on the slow rate of infiltration, asserting that it “does not account for the infiltration

galleries that are directly adjacent to Sheep Creek and would not have much time for

attenuation to occur before reaching the Creek.” Dissent, ¶ 152. This evinces another

misapprehension of the agency’s analysis. In the MPDES permitting process—which, it

bears repeating, has not been challenged—DEQ addressed a commenter’s similar concerns

about the agency’s determination “that Tintina will comply with the stricter summer

nitrogen standard by storing effluent in [the Treated Water Storage] pond while the

15
   Stefanie L. Whitmire & Stephen K. Hamilton, Rapid Removal of Nitrate and Sulfate in
Freshwater Wetland Sediments, J. Environ. Qual. 34:2062 (2005),
https://doi.org/10.2134/jeq2004.0483.
16
   Evelyn Uuemaa, Chris C. Palliser, Andrew O. Hughes & Chris C. Tanner, Effectiveness of a
Natural Headwater Wetland for Reducing Agricultural Nitrogen Loads, Water, Mar. 2018,
https://doi.org/10.3390/w10030287.

                                                58
standard is in effect.” The commenter asserted, “DEQ must analyze whether there is a

reasonable potential that Tintina’s discharges will violate the total nitrogen standard

applicable to Sheep Creek and impose additional permit requirements as necessary to meet

the standard.” Like in the MEPA review MTU challenges here, DEQ explained in response

that, based on “well-established science behind total nitrogen in soils,” the slow rate of

infiltration was “an indicator that total nitrogen will have time to attenuate in the soils and

may never reach the creek.” DEQ added that its “main concern,” and why the seasonal

discharges are important, was “where the UIGs are in close proximity to Sheep Creek[,] so

the total nitrogen in the discharge might quickly interact with Sheep Creek.” Contrary to

the Dissent’s conjecture, DEQ did consider the UIG’s proximity to the creek and explained

its decision to cut off the discharge while the seasonal limits are in effect.

¶92    “Because assessment of environmental impact fits squarely within an agency’s

significant technical and scientific expertise beyond the grasp of the Court, courts afford

great deference to agency decisions—here, DEQ’s evaluation of the significance of

potential adverse environmental impacts” from the discharge of groundwater via the UIG

during the July through September season. Water for Flathead’s Future, ¶ 21 (quotations

and citations omitted). The Dissent’s speculation cannot meet MEPA’s standards for

overturning DEQ’s determination. See § 75-1-201(6)(a)(i), MCA. Even if the record

contained conflicting evidence, “[t]he process of assigning relative weights to conflicting

data for predictive purposes is essentially a technical exercise requiring agency expertise

that should be afforded substantial deference.” Park Cty. Envtl. Council, ¶ 43.

                                              59
¶93    Whether a “hard look” has been given to the relevant information must

“contemplate the entirety of DEQ’s rationale.”       Water for Flathead’s Future, ¶ 24.

Considering the entire record, we conclude that MTU did not prove by clear and convincing

evidence that DEQ failed to take a “hard look” when evaluating the total nitrogen content

of Tintina’s discharge during the summer months. The agency considered relevant data,

including its extensive review for the MPDES permit, and articulated a reasoned

explanation for its rationale. Its determination was supported by substantial evidence and

was not arbitrary, random, or seemingly unmotivated based on the existing record. See

Clark Fork II, ¶ 34. The District Court’s ruling to the contrary is reversed.

¶94    Issue Three: Did DEQ satisfy MEPA when it considered and dismissed alternatives
       to the proposed action?

¶95    The District Court concluded that DEQ violated MEPA by failing to rationally

consider alternatives to Tintina’s proposed action. The court specified two alternatives in

particular: a depyritization alternative and the alternative of increasing binder content in

the surface tailings mixture.

¶96    MEPA requires that DEQ evaluate reasonable alternatives to a proposed action.

Section 75-1-201(1)(b)(iv)(C), MCA. The agency must “study, develop, and describe

appropriate alternatives to recommended courses of action in any proposal that involves

unresolved conflicts concerning alternative uses of available resources.”           Section

75-1-201(1)(b)(v), MCA.         “Under MEPA, an alternative analysis is defined as an

‘evaluation of different parameters, mitigation measures, or control measures that would

accomplish the same objectives as those included in the proposed action by the applicant.

                                            60
For a project that is not a state-sponsored project, it does not include an alternative facility

or an alternative to the proposed project itself.’” Park Cty. Envtl. Council, ¶ 47 (quoting

§ 75-1-220(1), MCA).            “Neither the alternatives analysis nor the resulting

recommendations bind the project sponsor to take a recommended course of action, but the

project sponsor may agree pursuant to [the statute] to a specific course of action.” Section

75-1-201(1)(b)(v), MCA.

¶97    DEQ identified twelve scoping alternatives to consider for detailed analysis. One

such alternative it considered was the possibility of increasing the cement content in the

tailings to reduce potential acid rock draining and water quality impacts. In the Final EIS,

Appendix A and Sections 2.3.2.6 (Increased Cement Content in Tailings) and 3.6.3.2

(Proposed Action) indicate that an increase in cement content beyond 2% would not offer

additional environmental benefits. Our discussion in Issue One makes clear that DEQ gave

adequate consideration to this alternative. The agency reasonably chose not to require a

higher concentration of cement content in the surface tailings. We need not address this

argument further.

¶98    Another alternative DEQ considered was the possibility of using a depyritization

method for tailings disposal. The District Court held that DEQ irrationally dismissed this

alternative against the recommendation of its consultant, “alleging without analysis that it

was not technically feasible and would not offer an environmental benefit.” Tintina and

DEQ dispute this finding. DEQ argues, citing the Final EIS, that it “provided analysis on

the very issue that [the consultant] had identified as needing additional analysis:

                                              61
underground storage of concentrated pyrite.”17 Tintina adds that, rather than focusing on

the agency’s decision-making process, the District Court simply disagreed with DEQ’s

resolution of conflicting evidence in the record. MTU counters that DEQ’s consultant

found “clear environmental advantages to removing pyrite from tailings” and

recommended more consideration of its technical feasibility. MTU maintains that DEQ

gave only a vague explanation in response, and the District Court appropriately faulted it

for inadequate analysis of the alternative.

¶99       Depyritization is the separation from mine tailings of sulfide materials, which

typically represent the largest source of acid generated at mine sites. Removal of the

sulfides produces tailings with relatively benign ARD potential; but because the

concentrated pyrite product has a much higher potential for acid generation, there must be

appropriate disposal options. Tintina assembled a working group of eighteen scientists and

engineers to identify feasible tailings storage methods for the project and rank the

alternatives. Two of the six alternatives the working group studied involved either partial

or full pyrite removal; they were ranked last among the alternatives. DEQ sought further

review of those two alternatives from its own consultant, ERM, which submitted a

technical memorandum at the end of 2017 analyzing the depyritization alternatives.

¶100 The ERM report noted that the cemented paste tailings option the working group

ranked first—despite having a “markedly higher total cost of paste tailings disposal”—

would minimize potential environmental impacts, including having the lowest impact to

17
     Pyrite (FeS2) is an iron sulfide mineral.
                                                 62
nearby designated wetlands, and that the CTF location alternative had “the smallest

catchment area footprint.” ERM also noted “some clear environmental advantages to

removing pyrite from tailings” and discussed some of the additional costs and practical

limitations the working group considered. ERM recommended that more consideration be

given to technical feasibility “rather than cost feasibility,” which it noted was among the

reasons the working group rejected a depyritization alternative.      In particular, ERM

suggested it was unclear how much more underground volume would be needed to dispose

of the concentrated pyrite fraction of the tailings.

¶101 Both MTU and the District Court selectively cite DEQ’s response to comments in

the Final EIS to conclude that the agency gave short shrift to ERM’s recommendations.

But both in the Description of Alternatives and in the Consolidated Response to concerns

regarding depyritization, DEQ explained its rationale, finding “no net environmental

benefit to full sulfide mineral separation prior to tailings disposal when compared to the

Proposed Action.” The Dissent asserts that DEQ did no more than “stat[e] there would be

no net environmental benefits[.]” Dissent, ¶ 158. The agency, however, acknowledged

the reduced risk of ARD but found problematic the challenges presented by either onsite

or offsite long-term storage and disposal. DEQ noted that it had been unable to find any

available options for offsite storage through operations in Montana or other western states

that would accept sulfide concentrates for disposal. Because it may not be feasible to

convert the pyrite concentrate into a cemented paste that would cure properly, the agency

determined that additional storage space on the mine site would require either a surface

                                              63
disposal facility or mining un-mineralized rock in order to provide storage, generating

perhaps as much as 7.6 million tons of additional waste rock to be disposed of on the

surface. Additional management strategies would have to be developed for long-term

storage to mitigate oxidation or spontaneous combustion, which DEQ concluded “may not

be technically feasible.” The alternatives analysis also pointed out that de-pyritizing

tailings uses more functional wetlands.

¶102 MTU seizes on DEQ’s use of the word “may” in several places within the

discussion, arguing that it insufficiently examined the alternative to show “a rational

connection between the facts found and the choice made.” Clark Fork. I, ¶ 47. A court

does not review an agency’s MEPA analysis, however, to determine whether a different

conclusion could have been reached. The court instead examines the agency’s explanation

to determine whether it considered “the relevant factors and whether there has been a clear

error of judgment.” Park Cty. Envtl. Council, ¶ 18 (quoting Clark Fork. I, ¶ 21). Again,

we focus on “the validity and appropriateness of the administrative decision-making

process without intense scrutiny of the decision itself.” Clark Fork. I, ¶ 47. Here, DEQ

appropriately had its independent consultant take a deeper look when Tintina’s working

group emphasized cost considerations in dismissing the depyritization alternatives. ERM

identified technical feasibility issues it suggested be considered more carefully, and DEQ’s

final review shows that the agency considered those challenges and decided to accept the

cemented paste tailings option (with modification) as the preferred action. MTU has not

                                            64
demonstrated that DEQ failed its responsibility under MEPA to consider reasonable

alternatives to the proposed action. See § 75-1-201(1)(b), MCA.

¶103 The standards for a court’s review of an agency’s determinations are well-settled.

The court does not supply its own “intense scrutiny of the decision.” Mont. Wildlife Fed’n,

¶ 43. It instead reviews the agency’s decision-making process for whether it acted

arbitrarily and capriciously. Water for Flathead’s Future, ¶ 12. Review under this standard

does not permit reversal even if the record contains inconsistent evidence or evidence that

could support a different result. Water for Flathead’s Future, ¶ 12. If the agency has

articulated “a rational connection between the facts found and the choice made,” the

decision will be upheld. Clark Fork I, ¶ 47.

                                      CONCLUSION

¶104 After carefully reviewing the record, we are satisfied that DEQ made a reasoned

decision. Clark Fork I, ¶ 21. Compiling an extensive record of scientific studies, expert

examinations, engineering reports, testing, and comparison with other mining facilities

around the world, and after considering a wide range of comments from members of the

public, including the Appellees, DEQ made a scientifically driven permitting decision that

was supported by substantial evidence. For the reasons explained in this Opinion, the

District Court’s order is reversed, and the case is remanded to the court to reinstate DEQ’s

decision to grant Tintina’s permit.

                                                 /S/ BETH BAKER

                                            65
We Concur:

/S/ MIKE McGRATH
/S/ JAMES JEREMIAH SHEA
/S/ JIM RICE
/S/ DIRK M. SANDEFUR

Justices Ingrid Gustafson and Laurie McKinnon, dissenting.

¶105 We disagree with the Court’s decision to reverse the District Court’s order revoking

the permit DEQ granted Tintina to construct the Black Butte Copper Mine. We would

uphold the District Court’s conclusion that DEQ’s approval of the permit was arbitrary and

not supported by substantial evidence.

¶106 The Montana Constitution provides at Art. II, Section 3, that each of us enjoys

inalienable rights, including “the right to a clean and healthful environment” and at Art.

IX, Section 1(1) that “[t]he state and each person shall maintain and improve a clean and

healthful environment in Montana for present and future generations.” The Legislature

enacted the Montana Metal Reclamation Act (MMRA) and MEPA to help meet its

constitutional obligation to prevent unreasonable environmental degradation. See 2003

Mont. Laws ch. 361, § 5 (HB437); see also § 75-1-102(1), MCA (MEPA’s purpose),

§ 82-4-302, MCA (MMRA’s purpose), Park Cnty. Envtl. Council v. Mont. Dep’t of Envtl.

Quality, 2020 MT 303, ¶ 67, 402 Mont. 168, 477 P.3d 288.

¶107 The proposed Black Butte Mine, operated by Tintina, is located adjacent to Sheep

Creek within the Smith River watershed. Tintina proposes to build a large copper mine—

to extract 14.5 million tons of copper ore over 13 years. This is expected to generate 12.9

                                            66
million tons of tailings, acid-generating processed minerals separated from the copper ore,

and 0.8 million tons of waste rock which will contain high-levels of acid-generating

minerals and toxic metals, including nickel, thallium, strontium, copper, lead, arsenic, and

uranium. The copper ore deposit to be mined is a sulfide ore body with high levels of acids

and toxic metals when exposed to air and water. Mining sulfide ore bodies, particularly

close to ground or surface water, presents inherent pollution risks, and even careful water

treatment and tailings waste management may be insufficient to avoid discharging noxious

chemicals to adjacent ground or surface water. Tintina intends to dispose of about half of

the mine tailings by backfilling underground areas of the mine with a mixture of cement

and tailings. The remainder of the tailings and all of the rock waste will be deposited

aboveground in a cemented tailings facility (CTF). A retaining dam would be used to

attempt to prevent the CTF from collapsing and discharging mine waste into Sheep Creek.

Tintina further proposes to convert the tailings into a non-flowable, low-strength solid by

consolidating them with cement, slag, and or fly ash.

¶108 When reviewing an application for a mining permit, DEQ must take a hard look at

environmental impacts of the proposed mine. Clark Fork Coal. v. Mont. Dep't of Envtl.

Quality, 2008 MT 407, ¶ 47, 347 Mont. 197, 197 P.3d 482 [hereinafter Clark Fork I]. An

agency must make an adequate compilation of relevant information, analyze it reasonably,

and consider all pertinent data. Clark Fork I, ¶ 47. The Court’s reversal of the District

Court’s Order allows a project with major environmental consequences to proceed despite

inadequate analysis and data in several key areas critical to the safety of the project. The

                                            67
Court correctly points out our caselaw supports deference to agencies for decisions

implicating substantial agency expertise and assigning weight to conflicting data. Opinion,

¶¶ 11-12 (citing Clark Fork I, ¶¶ 21, 47; Mont. Envtl. Info Ctr. v. Mont. Dep’t of Envtl.

Quality, 2019 MT 213, ¶ 20, 397 Mont. 161, 451 P.3d 493). However, there is a difference

between allowing an agency to weigh conflicting evidence and give a reasoned explanation

and allowing the agency to have significant gaps remain in the data or extrapolate beyond

what the data supports. It is true we do not reweigh the evidence or take a hard look

ourselves, but part of ensuring the agency took a hard look is to confirm the agency

thoroughly investigated the environmental implications of the project. Clark Fork I, ¶ 47.

¶109 While we have not found Montana case law where the agency did not take a hard

look, there is federal caselaw that demonstrates when an agency has not addressed

significant gaps in the data or has made inappropriate extrapolations. We have previously

held “since MEPA is modeled after the National Environmental Policy Act (NEPA),

federal case law construing parallel provisions in NEPA is persuasive.” Mont. Wildlife

Fed’n v. Mont. Bd. of Oil & Gas Conservation, 2012 MT 128, ¶ 32, 365 Mont. 232, 280

P.3d 877. The same requirement that agencies take a “hard look” is in federal caselaw

construing NEPA. Envtl. Def. Ctr. v. Bureau of Ocean Energy Mgmt., 36 F.4th 850, 872

(9th Cir. 2022).   An agency cannot “rely on incorrect assumptions or data” when

determining no significant environmental impact will occur. Native Ecosystems Council

v. United States Forest Serv., 418 F.3d 953, 964 (9th Cir. 2005). The Ninth Circuit has

reversed permits based on inadequate NEPA analyses due to incorrect assumptions, gaps

                                            68
in the data, and failure to disclose shortcomings in the data or models. Envtl. Def. Ctr., 36

F.4th at 874; Lands Council v. Forester of Region One of the United States Forest Serv.,

395 F.3d 1019, 1037 (9th Cir. 2004). This is exactly the case here, where the District Court

correctly identified many areas where the data was lacking or incorrect assumptions were

made.

¶110 Additionally, when the consequences of certain environmental decisions are greater,

it is even more imperative we take a critical look at potential gaps and extrapolations.

While DEQ did compile a voluminous and informative administrative record, it cannot

make up for the concerning gaps in the data and unwarranted extrapolations.

¶111 We would conclude the District Court correctly found: (1) DEQ violated the

MMRA and MEPA when it approved the safety and stability of the proposed CTF;

(2) DEQ violated the MMRA when it did not require Tintina to abide by the Independent

Review Panel (IRP) requirements; (3) DEQ violated MEPA when it approved the nitrogen

discharges into Sheep Creek; and (4) DEQ violated MEPA by failing to properly analyze

alternative storage facility designs.

¶112 1. Did DEQ satisfy MMRA and MEPA when it approved Tintina’s proposed
     tailings storage facility?

        A. DEQ violated the MMRA and MEPA when it approved Tintina’s permit.

¶113 The MMRA mandates that tailings storage facilities meet certain requirements to

protect human health and the environment. Section 82-4-301(2)(b), MCA. Before mining,

the MMRA requires applicants to obtain a mine operating permit from DEQ. Section 82-

4-335(1), MCA. Additionally, the applicant must submit a plan detailing the design,

                                             69
operation, and monitoring of impounding structures, including tailing storage

impoundments, sufficient to ensure that the structures are safe and stable. Section 82-4-

335(4)(l), MCA (emphasis added).

¶114 Here, the District Court found the DEQ failed to ensure the safety and stability of

Tintina’s tailings facility. Specifically, the District Court found DEQ failed to rationally

consider: (1) whether the mine tailings mixed with 0.5% cement and binders would form

and maintain a solid, non-flowable mass, (2) whether oxidation would undermine the

stability of the mass, and (3) whether there was potential for tailings liquefaction and what

impact that would have.

       1. Stability: DEQ’s analysis failed to properly determine whether the tailings will
       form a stable, non-flowable mass.

¶115 The Court concludes there was substantial evidence for DEQ to confirm the tailings

facility would be safe and stable, but this conclusion overlooks concerning gaps in the data

that were never properly accounted for and record evidence contradicting their findings

that was not adequately addressed in the final EIS. Opinion, ¶ 54. Mixing the tailings with

cement binder and storing that mixture above ground is a novel approach to tailings storage

that has never been fully implemented in the field. While this novel approach could be

more environmentally protective than previous methods, it does not mean adequate testing

and analysis can be bypassed. Since this is a new type of facility, with no similar facilities

to compare with, it is necessary to ensure every aspect of review is thoroughly completed

because of the potential catastrophic consequences. DEQ’s assumptions underlying the

                                             70
tailings being non-flowable are not fully supported by the record and some of their

explanations fail to account for important caveats.

¶116 For clarity purposes, we point out that there is a difference between a tailing layer

initially consolidating, meaning it has hardened but not fully cured, and a layer that has

reached final set, meaning it is fully cured. The Court correctly points out this difference,

but it accepts without sufficient evidence that the cemented tailings will initially harden

and become a non-flowable mass in a matter of days before a new layer of wet tailings is

added. Opinion, ¶ 46. DEQ’s and Tintina’s frequently asserted point that the tailings will

consolidate in a matter of days is not fully supported scientifically in the record, as the

areas Tintina and DEQ cite to simply have DEQ asserting this point without scientific

backing. The Court points to a memo from the project’s lead engineer dated September 2,

2016, where the engineer is speaking of the bleed water from the tailings storage facility

and states “[t]his bleed water may be noticeable for a few days, until cemented paste

tailings are consolidated.” This memo is about managing bleed water from tailings and

was not meant to assert the timeline for consolidation of the tailings based on concrete data.

The DEQ claims that once the tailings initially consolidate, they will become a

non-flowable mass. However, the DEQ does not offer any evidence that just because a

layer has initially consolidated, then it will be sufficiently stable before additional layers

are applied to withstand cracking and disaggregation from the weight of one or multiple

additional layers.

                                             71
¶117 If it takes 28 days for a 2% tailings mixture to reach final set or cure, and new layers

will be added on average every 7 to 30 days, then it is possible that three new layers could

be added on top of one layer before that layer has actually cured or reached final set.

Additionally, the DEQ presented no evidence on how long it takes 0.5% tailings mixtures

to cure or reach final set, even though it approved Tintina’s use of such. The Court reasons

that DEQ did not arbitrarily approve the use of 0.5% tailings because Tintina tested a range

consisting of 0% binder, 2% binder, and 4% binder and its expert consultants approved the

selected range. Opinion, ¶ 52. While we recognize this range of binder is not without

some basis in the record, we still hold concerns about the lower range of binder considering

0% binder was not tested for final set, only 2% and 4% binder were. Only index tests were

conducted with 0% binder at varying solids concentrations and only slump measurements

were taken, not any data about drying time or final set.

¶118 The slump tests that show low flowability even without binder are complicated by

the fact that the test used a higher solids percentage than will ever be used in operations,

as the test used between 82 and 84% solids and the tailings in the project will have around

79% solids. The slump test concluded that the optimum solids content for 2% binder was

79.5% but had no conclusions about the optimum amount for 0.5% binder as it was never

tested. DEQ admits as much in its brief when it asserts “tailings with higher total solid

content may perform just as well, if not better, than tailings with low total solid content

and higher binder percentage.” While it could be true that tailings with 79% solid content

                                             72
and a 0.5-2% binder may consolidate in a matter of days, DEQ has failed to show based on

record evidence that this is the case.

¶119 DEQ stated in its Final Environmental Impact Statement (FEIS) that “[o]nce [the

layer] sets, it would be a non-flowable mass.” However, DEQ does not clarify in this

instance whether it is referring to the layer reaching final set or merely attaining initial

hardening. This distinction is critical and should have been specifically noted by DEQ.

Even if a tailings layer initially consolidates after just a few days as DEQ asserts, that does

not necessarily mean it will dry to the point of being able to withstand multiple additional

layers before the layer fully sets or cures. If a tailing layer does not dry and stabilize to

withstand multiple additional layers, it will crack and disaggregate and will not form a

non-flowable mass. However, it is unclear whether the tailings will consolidate sufficiently

before additional layers are added because the DEQ failed to provide sufficient data on the

required dry time. A study of the Bulyanhulu mine, which stores uncemented ultra

thickened tailings above ground, confirmed that when tailings were layered without the

tailings below fully drying “they became unstable and lost geotechnical and environmental

benefits.”

¶120 The Court points to evidence of other mines in the record that store tailings in this

manner without binder and manage to achieve stability relatively quickly, but this ignores

the potential differences between those mines and Tintina’s plan authorized by DEQ.

Opinion, ¶ 35. As mentioned above, the amount of solids present in the paste is a key

factor to stability, and the record does not say what level of solids is present at the few

                                              73
other mines that have implemented this type of storage. Additionally, the thickness of the

layers of paste tailings also significantly affects the drying time, and one of the examples

mentioned in the record clarifies that the tailings are deposited in thin lifts of no more than

30 cm to ensure drying and stability before laying fresh tailings. Although DEQ states

Tintina plans to deposit the tailings in thin lifts, it does not specify or require a level of

thickness which ensures proper drying time. Additionally, although other mines have

successfully implemented storing paste tailings aboveground without any binder, the

Enviromin study states there were still issues with this storage method such as

“over-topping, erosion of paste within the facility (which increases pressure on dams), and

potential for static liquefaction accompanied by static or seismic slope instability.” While

the report goes on to suggest the addition of binder could help alleviate some of the

dominant concerns of surface placement of paste tailings, the report admits this has only

been partially implemented at one facility to date and the report does not specify the

minimum amount of binder that would be necessary to achieve some of these desired

effects.

¶121 DEQ notes Tintina will use a variation of binder ratios ranging between 0.5 and 2%

depending on operational requirements and tailings properties at the time of pouring.

However, the DEQ provides no analysis or explanation on whether using a range of

different tailings mixtures will affect the stability of the mass. DEQ chose such low

bindings percentages for the CTF “based on the distinct requirements for [the] final

placement area.” According to DEQ, if a higher percentage mixture, like 4%, was used in

                                              74
the CTF, it would not be feasible to pump the mixture to the storage facility, thus 0.5-2%

was the optimal ratio for pumping. DEQ cites to the tailings management alternatives

evaluation conducted by Tintina’s working group to support its assertion that a higher

percentage of binder would have no environmental benefits, yet the working group

evaluated 2% and 4% binder scenarios, never once using as low as 0.5% binder.

¶122 The Court also reasons that Tintina will use a liner and pump system to discharge

any water that accumulates in the CTF, there will be an embankment system to contain it,

and the safety of these features has not been challenged. Opinion, ¶¶ 38, 51. DEQ asserts

this Court “should find that the embankment and HDPE liners (without the cemented

tailings) would render the CTF safe and stable,” arguing that the cemented tailings are not

“necessary” to prevent environmental harm. Yet key components of DEQ’s analysis of the

safety and stability of the tailings facility depend on the tailings themselves being stable

and non-flowable, particularly in face of a possible dam breach or embankment failure, an

unlikely but viable threat. DEQ’s analysis on the risk of liquefaction in the case of seismic

activity depends on the tailings themselves being non-flowable, so the stability and

non-flowability of the tailings themselves was essential to DEQ’s overall conclusion of the

safety and stability of the CTF. The Court and DEQ attempt to deflect concerns about the

stability of the tailings themselves by repeatedly pointing out the structural integrity of the

liners, embankment, and the additional safety feature of the seepage pumps. While these

additional safety measures are important, DEQ’s argument that the stability of the tailings

themselves is unimportant because of the embankment and liner is undermined by their

                                              75
assertions that it is critical that the tailings achieve a stable, non-flowable mass. Just

because DEQ has additional measures in place that attempt to catch toxic water that comes

off the tailings within the CTF does not mean the tailings themselves will form a stable,

non-flowable mass sufficient to ensure the safety and stability of the structure.

¶123 This Court held an agency must supply a statement of reasoning why potential

impacts of a proposed action are nonsignificant. Clark Fork I, ¶ 48. For example, “[a]

simple statement that a perpetual discharge of polluted water will always be treated is

insufficient to justify a determination that an irreversible discharge is nonsignificant.”

Clark Fork I, ¶ 48. Such a simple basis of reasoning does not meet the “hard look” standard

required for MEPA approval. Here, the DEQ did not supply a statement of reasoning for

why Tintina did not conduct analysis on 0.5% tailings mixtures (other than because it only

had a limited amount of testing opportunities) and how the approved tailing layering was

“sufficient to ensure the safety and stability of the structure” as required by § 82-4-

335(4)(l), MCA.

¶124 Accordingly, the DEQ did not take a hard look at whether this would result in a

stable, non-flowable mass. Here, considering the massive volume of tailings to be

deposited in the CTF and the risk to human and environmental health should the tailings

become unstable, the risk associated with the project is very high.

¶125 DEQ arbitrarily assumed that a 0.5% tailings mixture would be sufficient to create

a stable, non-flowable mass without conducting analysis on that ratio. A mere statement

that 0.5% tailings will consolidate within days, without supporting evidence that the

                                             76
tailings will dry sufficiently to support additional layers and withstand cracking or

disintegration before reaching final set, is arbitrary and insufficient to justify DEQ’s

decision. Not only did DEQ act arbitrarily, and thus violate MEPA, when it approved the

use of 0.5% tailings mixture in the CTF without conducting any sort of analysis on that

tailing’s ratio, but it consequently failed to ensure the safety and stability of the CTF and

also violated the MMRA. The District Court did not substitute its judgment for DEQ’s as

the Court asserts. Rather, the District Court merely pointed out that DEQ failed to consider

rationally whether the mine tailings mixed with 0.5% binders—which was never studied

by Tintina or DEQ—would form and maintain a solid, non-flowable mass. The potential

consequences of the tailings being unstable and flowable in the event of an embankment

failure are catastrophic and DEQ’s failure to require adequate testing undermines their

finding that the tailings will be safe and stable.

       2. Oxidation: DEQ’s analysis failed to properly consider whether oxidation could
       weaken the stability of the tailings facility.

¶126 Regarding the risk of oxidation, the Court holds DEQ had sufficient evidence to

conclude there was low risk for the tailings to oxidize and threaten the stability of the

tailings facility. Opinion, ¶ 63. While the Court correctly provides some important context

not fully addressed by the District Court, it still allows DEQ too much deference when

DEQ failed to account for inconsistencies and extrapolations with its conclusion and the

record. DEQ in its technical memorandum explains “[n]ot all cracking is deleterious, as

some reaction products simply fill the cracks, retaining hydrologic and even structural

                                              77
integrity,” but the record fails to show when cracking is a cause for concern and when it is

not.

¶127 Tintina conducted HCT tests to examine the oxidation of the tailings. Oxidation

occurs when the tailings are exposed to air and water, which forms acid that can cause the

tailings to deteriorate.   Tintina’s tests involved humidity weathering cylinders that

simulated external forces. Tintina tested tailings with 0%, 2%, and 4% binder. The results

showed that oxidation was possible with all variations of cement binder.

¶128 DEQ ignored the test results, asserting that the cylinder testing is more aggressive

than what happens in the field, and for that reason it is not truly representative of field

conditions. Tintina, however, admitted in its permit application that it “do[es] not have

field data for a [CTF] to use and therefore cannot speculate as to how much slower the field

rate [of tailings disaggregation] will be” as compared to the weathering test results. As

such, Tintina asserted in its permit application that, until field conditions are simulated and

show otherwise, the cylinder weathering tests should be assumed to represent the reactivity

of the surface placed cemented-paste tailings. Thus, when the CTF is exposed to wetting

and drying conditions, like snow and rain, it should be assumed to react similar to the

cylinder conditions; however, without data to represent accurate field conditions, DEQ’s

dismissal of the test results is arbitrary. Further, Tintina’s testing showed that after two

weeks there was rapid acid generation, and after four weeks, the pH of tailings with 2%

cement binder dropped significantly to 3.6, and the cylinders disintegrated. Whereas the

0% binder went acidic immediately in the weathering cylinders.

                                              78
¶129 Even if the rate of weathering in the cylinders is faster than in the field, DEQ did

not take into consideration that Tintina plans on using mostly 0.5% tailings which,

presumably, could oxidize faster than the 2% tailings. Until accurate field conditions are

simulated, there is no way to get a true estimate.

¶130 Since Tintina did not conduct any analysis on 0.5% binder oxidation, nor whether

oxidation itself will affect the stability of the CTF, we cannot agree DEQ took a hard look.

Tintina plans on applying new layers of tailings every 7 to 30 days. If the weathering tests

Tintina conducted are correct, the tailings will oxidize and the cement in a layer with 2%

tailings mixture will start to disintegrate around the 30-day mark if it is exposed to air and

water. Nonetheless, the DEQ disregarded the tests and approved Tintina’s permit despite

this flawed and incomplete testing.

¶131 The Court points to other studies summarized in the Enviromin report that show

lack of acidification even with persistent cracking, but other studies from the report that

the District Court cited raise concerns about oxygen penetrating beneath the surface and

cracking that allows for more oxygen to penetrate and potentially create acidic conditions.

Opinion, ¶ 59. Although we do defer to agency expertise in the face of contrary evidence,

DEQ has failed to articulate why the potential cracking and oxidation is not a cause for

concern in the case of Tintina’s proposed mine. DEQ does not cite to any evidence in the

record showing why they concluded the cracking would not be deleterious and cause

issues. Shortly after the comment about cracking not always endangering structural

integrity, DEQ states “the surface cemented tailings would be fully contained within the

                                             79
CTF basin and require little structural integrity,” which directly contradicts the many areas

where DEQ and Tintina emphasize the importance of the stability of the paste tailings

themselves.

¶132 Additionally, the Court concludes DEQ rationally approved Tintina’s proposed

method of covering the tailings with a fresh lift every 7 to 30 days based on evidence that

other mines have found frequent lifts reduce oxidation, but the Court failed to account for

the vast difference between the frequency of the schedule Tintina proposed and the

frequency of the example mine relied upon. Opinion, ¶ 59. The Bulyanhulu mine featured

in the Enviromin report had applications of lifts every 5 days to prevent oxidation, yet DEQ

approved a much larger window. The Court points out the April 2017 Enviromin report

suggests covering the tailings with fresh lifts on the scale of weeks rather than days.

Opinion ¶ 59. While DEQ is entitled to rely on the recommendation of its expert

consultant, we still find this vague timeframe that the tailings could be deposited on the

scale of weeks to avoid oxidation not enough to be certain the selected timeframe will

minimize oxidation. The Court is correct that we should defer to DEQ’s expertise in

extrapolating the results from the HCT tests and the Bulyanhulu mine study, but the

reliance on the Bulyanhulu mine study and HCT tests is misplaced without further

explanation and data. Opinion, ¶ 59.

¶133 The Court explains that Tintina deliberately selected a binder range to allow for

flexibility in their operations to better respond to changing conditions on the ground and

planned for robust monitoring to ensure its implementation of tailings storage is safe and

                                             80
stable. Opinion, ¶ 40. The Court accepts that flexibility is necessary for Tintina to respond

to on-the-ground conditions and that ongoing monitoring will ensure the adjustments are

safe and effective. Opinion, ¶¶ 41-42. While we recognize flexibility is needed, especially

with a technology that has never been fully field tested, this cannot be used to excuse

obvious gaps in the data that could have been addressed through additional testing or data

collection and explanation. It might be true that some of these specifics cannot be fully

known until tested in the field, but as much as possible should be discovered upfront even

with ongoing monitoring and adjustments. Additionally, since the tailings storage will

have layers stacked upon it for years to come, it is important the base layers of the facility

are safe and stable or it could compromise the stability of the entire impoundment in the

future.

¶134 Without rigorous testing of the potential for oxidation, it was arbitrary for DEQ to

conclude Tintina’s tailing mixture layering plan ensured the safety and stability of the CTF

as required by the MMRA, § 82-4-335(4)(l), MCA.

          3. Liquefaction: DEQ’s analysis failed to properly consider the potential for
          liquefaction of the tailings.

¶135 The Court found DEQ had adequately reviewed the issue of liquefaction and come

to a reasonable conclusion determining there was no risk of liquefaction despite DEQ

failing to account for conflicting evidence in the record and extrapolating from its

consultant’s conclusions. Opinion, ¶ 71. The Court cites to DEQ’s explanations in the

record that dewatering and the subsequent low permeability of the paste tailings will

preclude any risk of liquefaction, but those cites to the record simply state these facts

                                             81
without any scientific references. Opinion, ¶ 67. The Court claims the conflicting evidence

from studies of other mines is not enough to show DEQ refused to take a hard look and

points to differences between the studies and Tintina’s proposed mine. Opinion, ¶ 69.

However, while we do defer to agency expertise on resolving conflicting evidence, DEQ

asserts there will be no risk of liquefaction and then fails to explain in the record why the

studies from other mines showing risk for liquefaction are not applicable.

¶136 According to DEQ, “[c]emented paste tailings are a stable, non-flowable (after

placement), low-strength solid when consolidated. This precludes the risk of liquefaction

or widespread release of tailings in response to impoundment failure or seismic events.”

Additionally, the DEQ claims:

       The primary benefit of paste deposition in a surface impoundment is that the
       process extracts much of the water from the tailings and causes the sand and
       silt particles that comprise tailings to pack together much more tightly than
       when deposited by water. This causes the material to have a low
       permeability, which restricts the flow of water and movement of oxygen
       through the tailings and precludes liquefaction during earthquakes because
       there is not sufficient water stored between the tailings grains to allow the
       material to move as a fluid in response to sudden agitation. The low
       permeability of paste tailings greatly reduces its potential for causing water
       pollution because very little water can move through the tailings[.]

However, a mere statement that the tailings are not subject to liquefaction because they are

a stable mass, or because they have little water content in them, is insufficient without

supporting evidence. The DEQ failed to provide any analysis on drying time for the 0.5%

tailings mixture, whether the layers must achieve a final set before becoming a stable,

non-flowable mass, or whether adding a new layer before a prior layer has reached final

set would make the tailings more susceptible to liquefaction.

                                             82
¶137 It is true the British Columbia mine determined to have liquefaction risk did not use

binder for their paste tailings, but Tintina proposes to use 0.5% to 2% binder and does not

show or explain that this range of binder will preclude liquefaction. The British Columbia

mine uses similar dewatering to make an extra thickened paste with low permeability that

DEQ claims should preclude liquefaction and yet DEQ does not point to any difference

aside from the addition of binder that would make Tintina’s storage facility not prone to

liquefaction. Further, the Environmin study stated uncemented paste tailings storage raised

issues regarding the potential for liquefaction. DEQ and Tintina fail to account for this

especially considering a minimal amount of binder at 0.5% will be most commonly used.

Additionally, Tintina mischaracterizes the Neves Corvo Mine study findings claiming they

were deposited in ponded water. However, examination of the full study referenced in the

record shows only a portion of the 2% binder test ended up in ponded water by accident

and that subsequently it suffered a substantial decrease in strength. The study overall points

to a need to have at least 1% binder to preclude liquefaction. The Neves Corvo Mine study

was conducted on backfill rather than surface tailings, but Tintina and DEQ want the Court

to dismiss this study rather than require specific evidence of whether additional pressure

increases risk for liquefaction. Data such as this is not contained in the record.

¶138 The Court points to a technical memorandum by DEQ’s consultant ERM where

ERM evaluated the novel technique of adding binder to surface tailings and found it would

increase resistance to seismicity. Opinion, ¶ 67. While the Court is correct this is evidence

that adding binder will help with liquefaction concerns and DEQ is entitled to rely on its

                                             83
expert consultant, the memorandum simply supports the general concept that cemented

tailings will be less prone to liquefaction than uncemented tailings. The memorandum does

not explicitly analyze Tintina’s proposed range of 0.5-2% binder. We find that given this,

there was not enough evidence in the record for DEQ to conclude there is no liquefaction

risk at all. Neither the ERM memorandum nor other studies referenced show that 0.5%

binder is enough to completely preclude any risk of liquefaction. We therefore conclude

that DEQ’s decision that there was no liquefaction risk was arbitrary and unreasonable.

¶139 DEQ did not take a hard look at whether liquefaction was or was not possible

because it did not evaluate the drying time for 0.5% tailings mixtures and assumed it would

form a stable mass sufficient to withstand liquefaction. The DEQ conducted analysis for

2 and 4% tailings mixtures, but not 0.5%. Simply stating liquefaction is not possible based

on the assumption the tailings have sufficient strength to withstand liquefaction is arbitrary

and unreasonable, especially considering DEQ has no evidence to support the conclusion

for a 0.5% tailings mixture.

       B. Tintina failed to meet the Independent Review Panel (IRP) process requirements
       of the MMRA.

¶140 The MMRA requires an IRP to review a design document submitted by the

applicant. Section 82-4-377(1), MCA. Among other things, the design document must

contain a detailed description of the proposed facility and site characteristics, maps and

design drawings, and other design specifications. Section 82-4-376(2), MCA. The IRP

must review the document and assess the application of technology in the proposed design.

Section 82-4-377(8), MCA. The IRP then submits its review and any modifications to the

                                             84
permit applicant and the DEQ. Section 82-4-377(9), MCA. Then, the engineer of record

modifies the document to implement the changes, and the permit applicant sends the final

design document to the DEQ. Section 82-4-377(10), MCA.

¶141 The Court affirms that the plain language of MMRA requires an IRP to examine a

design document with all required elements listed in § 82-4-376, MCA, yet subsequently

finds the IRP reviewed “substantial[ly the] information required by MMRA” despite

several required analyses being provided after the IRP issued their report. Opinion,

¶¶ 76-77. The plain language of the MMRA does not support submission of the required

elements of the design document in a piecemeal fashion, including documents submitted

after the IRP produced its final report in support of the mining permit. Section 82-4-377,

MCA. The Court acknowledges the relevant statute does not allow for an applicant to

submit a design document missing crucial required information, does not allow the IRP to

issue its report absent consideration of all the required information, and does not allow the

applicant to submit required information directly to the DEQ without the IRP ever seeing

it. Yet, that is essentially what the Court sanctions when it concludes the IRP review was

adequate here. Opinion, ¶ 76.

¶142 Here, Tintina submitted its design document to the IRP in July 2017. It did not

contain a construction management plan, a completed seismic analysis, or a dam breach

risk assessment.

¶143 DEQ argues all the information was submitted, albeit piecemeal, to the IRP prior to

its approval, and that should suffice under the MMRA. However, the statute provides the

                                             85
design document must include a construction management plan, a probabilistic and

deterministic seismic evaluation for the area, and a dam breach analysis. Sections 84-4-

376(m), (n), (s), MCA.

¶144 Here, the design document itself states “[a] site specific construction management

plan will be developed for the CTF during the detailed design phase.” Tintina and DEQ

acknowledge that the required “construction management plan” was never submitted to the

IRP but claim all the substantive requirements of the plan can be found in the TOMS

manual. However, the TOMS manual was created to comply with the separate TOMS

manual requirements of MMRA, not to satisfy the construction management plan. Section

82-4-379, MCA. The Court accepts the TOMS manual as meeting the requirements of the

construction management plan; however, this allows for the submission of required

materials in a potentially confusing and misleading format. Opinion, ¶ 80. The TOMS

manual is generated by a separate statutory requirement from the construction management

plan. While there is overlap, each is generated pursuant to separate statutory requirements

and purposes.    Section 82-4-379, MCA; Section 82-4-376(2)(s), MCA.             We have

previously held that required information submitted as part of an Environmental

Assessment (EA) but organized to fulfill other requirements leads to a confusing and

non-cohesive product, thus making it difficult to assess if all the statutory requirements

have been met. Citizens for Resp. Dev. v. Sanders Cnty. Comm., 2009 MT 182, ¶ 20, 351

Mont. 40, 208 P.3d 876. We reasoned the “information which could be relevant to the EA

is buried in documents created primarily for other purposes” and “much of the relevant

                                            86
information was not provided in a cohesive format.” Citizens for Responsible Dev., ¶¶ 20,

25.

¶145 The case is similar here. While the TOMS manual might fulfill many of the

requirements of a construction management plan, Tintina should have prepared a separate

construction management plan for the IRP to review to avoid confusion and burying of

relevant information.

¶146 While there was “some seismic analysis” reviewed by the IRP, it was not in the

design document but in its Waste and Water Management Design for Mine Operating

Permit and it did not include the required “probabilistic and deterministic seismic

evaluation.”   Section 82-4-376(m), MCA. A DEQ staff member in a memo dated

August 11, 2017, noted the probabilistic and deterministic seismic analyses were not

provided to DEQ in any document but that Knight Piésold Consulting indicated those

evaluations would be completed soon and distributed. Tintina included the required

analysis in its revised design document to DEQ submitted on September 12, 2017, but there

is no evidence in the record that the IRP ever reviewed this required analysis directly. By

the date of the conference call between Tintina, DEQ, and the IRP that occurred on

August 11, this analysis was yet to be completed as indicated in the follow up memo. Even

if eventually the IRP was given this required analysis when the revised design document

was completed in September, the IRP during the earlier conference call indicated it was

satisfied and would not be issuing any additional recommendations although it had never

seen the completed seismic analysis. Despite all this, the Court concludes Tintina and DEQ

                                            87
complied because the analysis was completed and the IRP indicated it was satisfied with

Tintina’s materials and saw no need to issue further recommendations. Opinion, ¶ 81. The

statute is clear, however, the IRP must review this element; Tintina’s eventual analysis of

the information and subsequent submission to DEQ do not satisfy the requirements of the

statute. Section 82-4-377, MCA; Section 82-4-376(m), MCA.

¶147 Tintina did not submit a dam breach analysis until August 11, 2017, at least two

weeks after the IRP approved the design document on July 28, 2017. Although the IRP

did eventually review the dam breach analysis, it was only after issuing its final report. As

the Court stated, it is not logical to allow an applicant to submit a design document with

crucial pieces missing and only provide those statutorily required pieces after a final report

has been issued by the IRP. Opinion, ¶ 76. Although the Court was satisfied that the IRP

did eventually review the dam breach analysis and saw no need to change its

recommendation, this ignores the clear statutory requirements an applicant must follow.

Additionally, although there is no evidence of it in this case, there is the potential risk that

an IRP may become invested in its initial decision and be less willing to consider additional

information and change their recommendation after a final report has been issued. Even if

a timely review would not have changed the outcome in this case, it is unacceptable to

excuse clear statutory violations of an environmental review process. In Citizens for

Responsible Development, we held the Board of Commissioners approval of a subdivision

without receiving all the statutorily required EA components was unlawful. Citizens for

Responsible Dev., ¶ 25. The approval was reversed based on the EA missing statutorily

                                              88
required explanations and for the piecemeal format in which much of the information was

provided. Citizens for Responsible Dev., ¶ 26.

¶148 While the Court maintains Montana Trout Unlimited (MTU) did not suggest a

substantially different outcome might have occurred if the IRP had issued its report after

considering all the required materials, we cannot subscribe to the Court’s interjection of

“harmless error” principles into an environmental statute when the statute is clear.

Opinion, ¶ 81. The statutes are designed to ensure that proper procedures and a specific

process is followed before an agency issues its decision. “The judiciary’s standard remedy

for permits or authorizations improperly issued without required procedures is to set them

aside.” Park Cnty. Env’t Council, ¶ 55. Tintina and the IRP did not comply with statutory

mandates and DEQ should not have allowed this review to unfold in a piecemeal fashion

contrary to the clear dictates of the statute. In our opinion, the Court errs when it concludes

the result, nevertheless, would be the same. This Court’s obligation is to ensure the

statutory process, which is designed to produce thorough and well-informed decisions by

the agency, is followed. If those statutory processes are followed, it is only then that the

agency is entitled to a deferential standard of review.

¶149 2. Did DEQ satisfy MEPA when it approved the storage facility’s nitrogen
     discharges into Sheep Creek?

¶150 Tintina and DEQ’s responses that the lagging effluent will not violate the

non-degradation limit for total nitrogen once mixed with the surface water are contradicted

in the record. DEQ specifically rejected a mixing zone for the effluent into Sheep Creek

because the nitrogen levels in the Creek were already at or above the non-degradation limit

                                              89
during the summer months. DEQ determined Sheep Creek had no assimilative capacity

during the summer months to absorb more nitrogen and required Tintina to hold the

wastewater from July 1 to September 30. The MPDES permit requires a 0.09 mg/L effluent

limitation on total nitrogen, not a limitation on the total nitrogen once it mixes with the

surface water. The average estimated total nitrogen coming from the effluent going into

Sheep Creek is 0.32 mg/L. It was predicted to reduce to just under 0.12 mg/L only after

mixing with the surface water in Sheep Creek. Since there was no mixing zone authorized,

the effluent itself must be 0.09 mg/L or under to meet the non-degradation standard.

¶151 The Court holds DEQ’s conclusion about the effluent not having a significant

impact on Sheep Creek was reasonable and supported by substantial evidence, but DEQ

failed to account for the significant and concerning gaps in the record. DEQ failed to

identify how much nitrogen would be filtered out prior to the discharged water’s entering

Sheep Creek. Even if the alluvial sands and wetlands do filter nitrogen, the levels entering

Sheep Creek may nonetheless be higher than the 0.09 mg/L limit. The DEQ arbitrarily

approved Tintina’s permit when it knew that discharged water, containing up to 0.57 mg/L

of nitrogen, may enter Sheep Creek during the months of July-September when the limit is

0.09 mg/L.

¶152 Further, the studies relied on by DEQ in responding to comments in the final EIS

are about natural wetlands in vastly different environments than Montana, and there is no

explanation in the record about why these sources should be applied without modification

to the UIGs and alluvial sands. However, in the modeling commissioned by Hydrometrics

                                            90
for the MPDES permit, Tintina’s predictions show the total nitrogen will not be under 0.09

mg/L even after mixing with the water in Sheep’s Creek. If DEQ’s explanation that

attenuation will remove the nitrogen down to below the non-degradation limit is to be

believed, then it does not make sense that the water must be withheld during the summer

months because it will be above the non-degradation limit. Further, DEQ’s assertion that

the potential slow rate of infiltration will result in more nitrogen being removed does not

account for the infiltration galleries that are directly adjacent to Sheep Creek and would

not have much time for attenuation to occur before reaching the Creek. The UIGs will

consist of 14 individual infiltration galleries ranging from 150 feet to 350 feet, with the

closest being immediately adjacent to the stream and the farthest being approximately 600

feet away. Since Tintina is only instructed to hold the water starting on July 1st and the

non-degradation limit is in place also starting July 1, any water released into the galleries

immediately near Sheep Creek will have little filtration time before reaching the Creek

when the non-degradation limit is in place. DEQ merely asserts wetlands and alluvial sands

will lower the nitrogen levels without providing concrete, supporting evidence (other than

generally wetlands are known to filter out nitrogen to some degree) to connect the facts to

the decision. See Clark Fork I, ¶ 48.

¶153 MTU has shown by clear and convincing evidence that contradictory information

in the record has not been accounted for by DEQ in a satisfactory manner. Section 75-1-

201(6)(a)(i), MCA. While the Court is correct that in the face of conflicting scientific

evidence we defer to the agency’s expertise, there is a difference between conflicting

                                             91
evidence and a lack of evidence or unfounded extrapolation. Opinion, ¶ 92. Given the

findings related to the mixing zone and the lack of explanation of how to adapt the scientific

findings of attenuation to the differing environment of the UIG, we would conclude the

District Court was correct in determining DEQ failed to “examine all relevant data and

articulate a satisfactory explanation” when DEQ found the effluent discharges would not

harm water quality in Sheep Creek. Clark Fork I, ¶ 47.

¶154 3. Did DEQ meet the requirements of MEPA when it considered alternatives to
     the proposed project?

¶155 DEQ screened 13 alternative ideas for the proposed project—12 were dismissed

before further analysis was conducted because they did not meet one of the four screening

criteria DEQ used. DEQ considered whether the alternative idea: (1) met the project

purpose and need, (2) was technically feasible, (3) was economically feasible, and (4) had

a significant environmental benefit as compared to the proposed project.

¶156 Under MEPA, an alternative analysis is defined as an “evaluation of different

parameters, mitigation measures, or control measures that would accomplish the same

objectives as those included in the proposed action by the applicant. For a project that is

not a state-sponsored project, it does not include an alternative facility or an alternative to

the proposed project itself.” Section 75-1-220(1), MCA. DEQ cites to the 2021 MEPA

Handbook which refers to a reasonable alternative as one that is practical, technically

possible, and economically feasible.

¶157 Here, DEQ eliminated the two alternatives that the District Court thought should be

considered and evaluated by merely stating they were not in line with its selective criteria.

                                              92
Regarding both the Increased Cement Content in Tailings Alternative and the Separate

Sulfide Prior to Tailings Disposal Alternative, DEQ simply stated those alternatives would

not provide additional net environmental benefits without conducting enough analysis.

¶158 DEQ’s expert, Environmental Resources Management (ERM), wrote a technical

memorandum that provided there were some clear environmental advantages to removing

pyrite from the tailings. ERM also provided DEQ should take a closer look at the pros and

cons of this method rather than just the cost feasibility. While DEQ did conduct further

analysis on this option, it stopped short of conducting a full analysis after concluding there

would be no net environmental benefit. DEQ’s explanation did not meet the hard look

standard because after the ERM suggested there are environmental benefits to separating

the sulfide, DEQ’s examination was shallow, without further research, and lacked citation.

Simply stating there would be no net environmental benefits does not meet the hard look

standard required by MEPA. Additionally, it is puzzling how DEQ can conclude there

would be no net environmental benefits before conducting a full analysis of the alternative.

Accordingly, DEQ failed to take an initial hard look at whether either of these two options

would be a sufficient alternative on the basis that neither would have a net environmental

benefit.

¶159 Ultimately, DEQ did not take the required hard look into the safety and stability of

the tailings storge, the IRP review process, and the nitrogen discharges into Sheep Creek.

While many aspects of DEQ’s review were adequate and the District Court did fail to

account for some reasoned explanations, there were still gaps remaining that the Court

                                             93
overlooks in reversing the District Court’s order. We cannot defer to an inadequate

analysis unsupported by the record. We would affirm the District Court’s determination

that DEQ’s issuance of the mine permit was arbitrary, capricious, and unlawful, and

remand to DEQ.

                                              /S/ INGRID GUSTAFSON
                                              /S/ LAURIE McKINNON

                                         94