DRAFT SAMPLING AND MONITORING PLAN — ALL SITES
Appendix C to Consent Decree
UNITED STATES DISTRICT COURT DISTRICT OF MONTANA MISSOULA DIVISION
UNITED STATES OF AMERICA and STATE OF MONTANA, Plaintiffs,
consolidated with
STATE OF NEVADA and STATE OF WEST VIRGINIA, Co-Plaintiffs,
v.
TORCHLIGHT MINING CORP.; TORCHLIGHT MINING (U.S.) INC.; TORCHLIGHT SPECIALTY CHEMICALS, INC.; RIDGECREST MINE HOLDINGS, LLC; and BONANZA CREEK MINING, LLC, Defendants.
Civil Action No. 9:24-cv-00087-DWM
February 24, 2025
Prepared by:
Pinnacle Creek Environmental, LLC 320 Willowbrook Drive, Suite 100 Bozeman, Montana 59715
Engagement Lead: Dr. Astrid Bergmann, P.E., Senior Principal
Prepared on Behalf of: Torchlight Mining Corp. and its U.S. Subsidiaries
Submitted for Review by: Calderwood & Harkness LLP Matter No. 1039-00003
DRAFT STATUS: This document is submitted in draft form for review and approval by the United States Environmental Protection Agency and the United States Department of Justice, Environment and Natural Resources Division, pursuant to the terms of the Consent Decree (Execution Version dated February 19, 2025) in Civil Action No. 9:24-cv-00087-DWM. This Draft Sampling and Monitoring Plan is intended for attachment to the Consent Decree as Appendix C and shall not become effective until approved in writing by EPA, the applicable state agencies, and the Court-appointed independent environmental monitor, Verdant Analytics, Inc. All terms, conditions, and provisions herein are subject to revision based on regulatory review comments.
LIST OF TABLES
LIST OF FIGURES
LIST OF ACRONYMS AND ABBREVIATIONS
SECTION 1: INTRODUCTION AND PURPOSE
1.1 Purpose and Objectives
This Sampling and Monitoring Plan ("SMP" or "Plan") is prepared as Appendix C to the Consent Decree entered in United States of America and State of Montana v. Torchlight Mining Corp., Torchlight Mining (U.S.) Inc., Torchlight Specialty Chemicals, Inc., Ridgecrest Mine Holdings, LLC, and Bonanza Creek Mining, LLC (consolidated with the State of Nevada and State of West Virginia as co-plaintiffs), Civil Action No. 9:24-cv-00087-DWM, filed in the United States District Court for the District of Montana, Missoula Division. The Consent Decree was lodged with the Court on February 19, 2025, and this Plan accompanies the Execution Version of the Consent Decree dated the same date.
The fundamental purpose of this Plan is to establish a comprehensive, consistent, and scientifically defensible framework for environmental monitoring across all four sites addressed by the Consent Decree. This framework is designed to serve the following objectives:
(a) Establish and maintain monitoring well networks adequate in scope and density to characterize groundwater conditions, track contaminant migration, and verify compliance with remedial action performance standards at each of the four sites;
(b) Specify sampling frequencies for all environmental media — including groundwater, surface water, sediment, soil, and air/vapor — that are sufficient to detect changes in contaminant concentrations over time and to identify potential remedy failures or new contaminant releases with adequate temporal resolution;
(c) Define analyte lists, analytical methods, method detection limits (MDLs), and practical quantitation limits (PQLs) for each site and each environmental medium, ensuring that the analytical program is capable of detecting contaminants of concern at concentrations relevant to applicable regulatory standards and performance criteria;
(d) Establish quality assurance and quality control (QA/QC) protocols that comply with EPA SW-846 methods, applicable EPA region-specific quality assurance project plan (QAPP) requirements, and state laboratory certification standards, thereby ensuring the defensibility and reliability of all monitoring data generated under this Plan;
(e) Define reporting requirements — including quarterly monitoring reports, annual monitoring reports, exceedance and incident reports, and five-year review reports — that provide timely and transparent communication of monitoring results to EPA, applicable state regulatory agencies, the Court-appointed independent environmental monitor, and the responsible parties;
(f) Provide a framework for data evaluation and statistical analysis that supports objective assessment of contaminant trends, comparison of monitoring results to performance standards and cleanup levels, and verification of completion criteria; and
(g) Establish procedures for adaptive management and plan modification that allow the monitoring program to evolve in response to changing site conditions, new scientific information, remedy modifications, and regulatory developments, subject to appropriate approval processes.
This Plan is subject to review and approval by the United States Environmental Protection Agency (EPA), through the lead Regional Project Coordinators for each site, and by the Court-appointed independent environmental monitor, Verdant Analytics, Inc., under the direction of Dr. Kamal Osei, Senior Managing Director. No monitoring activities described herein shall commence until this Plan has received written approval from EPA and Verdant Analytics, except to the extent that interim monitoring activities are separately authorized under the Consent Decree or existing regulatory permits.
The Plan is structured to address each of the four Consent Decree sites individually while maintaining consistency in general protocols, QA/QC requirements, and reporting formats. This approach recognizes that each site presents distinct environmental conditions, contaminant profiles, and regulatory contexts, while also reflecting the Consent Decree's objective of establishing a unified monitoring program administered by a single environmental remediation consultant, Pinnacle Creek Environmental, LLC, on behalf of all defendant entities.
1.2 Regulatory Framework
This Plan has been developed in accordance with, and is intended to satisfy the monitoring requirements imposed by, the following federal and state regulatory authorities and legal instruments:
Federal Statutes and Regulations:
(a) Clean Water Act (CWA) § 301, 33 U.S.C. § 1311, which prohibits the discharge of pollutants from point sources to navigable waters of the United States except in compliance with applicable permits and standards, and which provides the basis for enforcement actions related to unpermitted or permit-violating discharges from the sites addressed by this Plan;
(b) Resource Conservation and Recovery Act (RCRA) §§ 3004 and 3005, 42 U.S.C. §§ 6924 and 6925, which establish standards for owners and operators of hazardous waste treatment, storage, and disposal facilities and require corrective action for releases of hazardous waste and hazardous constituents, and which apply directly to the Gallatin Chemical Works (Permit No. MTD098712456) and the Kanawha Bend Chemical Plant (Permit No. WVD048823915);
(c) Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) § 107, 42 U.S.C. § 9607, which establishes liability for response costs and natural resource damages associated with releases of hazardous substances, and which provides the basis for the remediation obligations at the Ridgecrest Copper-Molybdenum Mine, a site proposed for listing on the National Priorities List (NPL) and currently addressed under Administrative Order on Consent (AOC) Docket No. CERCLA-08-2022-0039 (executed September 15, 2022);
(d) OSHA 29 CFR 1910.120, the Hazardous Waste Operations and Emergency Response (HAZWOPER) standard, which governs health and safety requirements for personnel engaged in hazardous waste site operations, including environmental monitoring activities conducted under this Plan;
EPA Guidance Documents:
(e) RCRA Groundwater Monitoring Technical Enforcement Guidance Document (TEGD), EPA/530-R-93-001, as revised, which provides technical guidance for design, installation, and operation of groundwater monitoring systems at RCRA facilities;
(f) CERCLA RI/FS Guidance, EPA 540-R-06-060, which establishes the framework for remedial investigations and feasibility studies and provides guidance on monitoring program design for CERCLA sites;
(g) EPA region-specific quality assurance project plan (QAPP) requirements, including the EPA Region 8 QAPP template for environmental monitoring at Superfund and RCRA corrective action sites, and comparable QAPP requirements for EPA Regions 3 and 9;
(h) EPA OSWER Technical Guide for Assessing and Mitigating the Vapor Intrusion Pathway (OSWER Publication 9200.2-154), which provides guidance on evaluating potential vapor intrusion from subsurface contamination to occupied structures and is applicable to the Gallatin Chemical Works vapor intrusion assessment described in Section 4.6 of this Plan;
(i) EPA Ambient Air Monitoring Reference and Equivalent Methods (40 CFR Part 58), applicable to the fenceline air monitoring program at the Kanawha Bend Chemical Plant described in Section 6.7;
State Regulatory Requirements:
(j) Montana Department of Environmental Quality (Montana DEQ) — Montana Pollutant Discharge Elimination System (MPDES) permit requirements applicable to the Ridgecrest Copper-Molybdenum Mine and the Gallatin Chemical Works; Montana groundwater quality standards (Administrative Rules of Montana, Title 17, Chapter 30, Subchapter 10); Montana surface water quality standards (ARM Title 17, Chapter 30, Subchapter 6);
(k) Nevada Department of Environmental Protection (Nevada DEP) — Nevada water pollution control permits applicable to the Bonanza Creek Gold Mine; Nevada water quality standards (Nevada Administrative Code Chapter 445A); Nevada mining reclamation requirements;
(l) West Virginia Department of Environmental Protection (WV DEP) — National Pollutant Discharge Elimination System (NPDES) permit requirements applicable to the Kanawha Bend Chemical Plant; RCRA state-authorized corrective action permits; West Virginia groundwater quality standards (47 CSR 12); West Virginia surface water quality standards (47 CSR 2);
Consent Decree Performance Standards and Completion Criteria:
(m) This Plan is designed to verify compliance with the performance standards and completion criteria established in the Consent Decree, as set forth in Sections 7 through 12 of the Consent Decree (Execution Version, February 19, 2025), the Performance Standards and Completion Criteria Memorandum (attached to the Consent Decree as Appendix B), and the Consolidated Remediation Milestone Matrix (attached to the Consent Decree as Appendix D). Specific performance standards applicable to each site are identified in the site-specific monitoring sections (Sections 3 through 6) of this Plan.
1.3 Scope and Applicability
This Plan applies to environmental monitoring activities at the following four sites, which are collectively subject to the remediation obligations established by the Consent Decree:
Site 1 — Ridgecrest Copper-Molybdenum Mine
Location: 14200 Ridgecrest Mine Road, Drummond, Granite County, Montana 59832
EPA Lead Region: Region 8
Property Description: The Ridgecrest Mine encompasses approximately 3,200 acres of mine footprint, including the open pit, waste rock dumps, the 425-acre tailings impoundment, ore processing facilities, haul roads, and associated infrastructure. The total controlled property, including buffer lands, water rights holdings, and undeveloped parcels, covers approximately 8,700 acres. The mine is situated in the upper Flint Creek watershed in the northern Flint Creek Range of the Rocky Mountains, at elevations ranging from approximately 5,200 to 7,400 feet above mean sea level. The site is located approximately 12 miles northwest of the town of Drummond, Montana.
Site 2 — Gallatin Chemical Works
Location: 8800 Industrial Park Lane, Belgrade, Gallatin County, Montana 59714
EPA Lead Region: Region 8
Property Description: The Gallatin Chemical Works occupies approximately 145 acres within the Belgrade Industrial Park, located approximately 3 miles west of the city of Belgrade and 10 miles west of Bozeman, Montana, in the Gallatin Valley. The facility is situated on relatively flat terrain at an elevation of approximately 4,450 feet above mean sea level. The property includes chemical manufacturing buildings, raw material storage areas, product warehousing, a wastewater treatment system, three identified Solid Waste Management Units (SWMUs), and administrative offices.
Site 3 — Bonanza Creek Gold Mine
Location: County Road 447, Mile Marker 12, Lander County, Nevada 89820 (approximately 28 miles south of Battle Mountain, Nevada)
EPA Lead Region: Region 9
Property Description: The Bonanza Creek Gold Mine encompasses approximately 5,600 acres of mine footprint, including the open pit, heap-leach pads, solution ponds, processing facilities, waste rock storage areas, and associated mining infrastructure. The total controlled property, including unpatented mining claims and fee-simple parcels, covers approximately 12,400 acres. The site is located in the northern Great Basin physiographic province, within the Reese River drainage basin, at elevations ranging from approximately 4,800 to 6,200 feet above mean sea level. Terrain is characterized by arid to semi-arid conditions with sparse sagebrush-grassland vegetation.
Site 4 — Kanawha Bend Chemical Plant
Location: 2200 Chemical Valley Road, Institute, Kanawha County, West Virginia 25112
EPA Lead Region: Region 3
Property Description: The Kanawha Bend Chemical Plant occupies approximately 78 acres along the Kanawha River in the community of Institute, approximately 10 miles west of downtown Charleston, West Virginia. The facility is located within the Kanawha Valley industrial corridor, commonly known as "Chemical Valley." The property includes chemical manufacturing buildings, tank farms, a former waste lagoon (closed in situ), a sulfuric acid regeneration unit, raw material and product storage areas, wastewater treatment facilities, and administrative offices. Site terrain is generally flat with gentle slopes toward the Kanawha River and an unnamed tributary that traverses the eastern portion of the property.
Environmental Media Covered: This Plan addresses monitoring of the following environmental media, as applicable on a site-by-site basis:
• Groundwater (all four sites)
• Surface water (all four sites)
• Sediment (Ridgecrest and Bonanza Creek)
• Soil (all four sites)
• Air and vapor (Kanawha Bend — fenceline ambient air monitoring; Gallatin Chemical Works — sub-slab vapor and indoor air)
• Tailings impoundment water and stability instrumentation (Ridgecrest)
• Heap-leach pad solution and liner integrity (Bonanza Creek)
• Pit-lake water (Ridgecrest and Bonanza Creek)
• DNAPL presence and distribution (Kanawha Bend)
1.4 Responsible Parties
The following entities and individuals bear responsibility for the implementation, oversight, and review of the monitoring program established by this Plan:
Defendants / Responsible Parties:
Torchlight Mining Corp. ("TMC") is the ultimate parent company and bears primary responsibility for all remediation obligations under the Consent Decree. TMC discharges its obligations through the following wholly owned U.S. subsidiaries, each of which is a named defendant:
• Torchlight Mining (U.S.) Inc. (EIN: 83-2047156) — the U.S. holding company for TMC's mining and chemical operations in the United States.
• Torchlight Specialty Chemicals, Inc. (EIN: 47-3819204) — the operating entity for the Gallatin Chemical Works and the Kanawha Bend Chemical Plant.
• Ridgecrest Mine Holdings, LLC (Montana Secretary of State ID: E1042738) — the operating entity and landowner for the Ridgecrest Copper-Molybdenum Mine, wholly owned by Torchlight Mining (U.S.) Inc.
• Bonanza Creek Mining, LLC (Nevada Secretary of State Entity No.: E0518294731) — the operating entity and mining claim holder for the Bonanza Creek Gold Mine, wholly owned by Torchlight Mining (U.S.) Inc.
Environmental Remediation Consultant:
Pinnacle Creek Environmental, LLC ("Pinnacle Creek"), 320 Willowbrook Drive, Suite 100, Bozeman, Montana 59715, serves as the environmental remediation consultant responsible for preparation and implementation of this Plan and all site-specific monitoring activities described herein. The Engagement Lead is Dr. Astrid Bergmann, P.E., Senior Principal. Pinnacle Creek has been engaged by TMC through Calderwood & Harkness LLP under Matter No. 1039-00003 and is responsible for field sampling, data management, data evaluation, and preparation of all monitoring reports required by this Plan.
Independent Environmental Monitor:
Verdant Analytics, Inc. ("Verdant Analytics"), serves as the Court-appointed independent environmental monitor pursuant to the Consent Decree and the Independent Monitor Agreement (execution version dated February 15, 2025). Dr. Kamal Osei, Senior Managing Director, is the designated lead for Verdant Analytics' monitoring oversight activities. Verdant Analytics is entitled to review all monitoring data and reports generated under this Plan, conduct independent split sampling and verification sampling, and prepare quarterly compliance audit reports and annual public compliance reports.
EPA Project Coordinators:
The following EPA personnel serve as the designated Project Coordinators for each site:
• Ridgecrest Copper-Molybdenum Mine (EPA Region 8): Dr. Samuel Tesfaye, Remedial Project Manager, Superfund and Emergency Management Division, EPA Region 8, Denver, Colorado.
• Gallatin Chemical Works (EPA Region 8): EPA Region 8 Project Coordinator, Corrective Action Program, to be designated in writing by EPA Region 8 within 30 days of the Effective Date of the Consent Decree.
• Bonanza Creek Gold Mine (EPA Region 9): Jennifer Whitfield, Remedial Project Manager, Superfund and Emergency Response Division, EPA Region 9, San Francisco, California.
• Kanawha Bend Chemical Plant (EPA Region 3): EPA Region 3 Project Coordinator, Land, Chemicals and Redevelopment Division, to be designated in writing by EPA Region 3 within 30 days of the Effective Date of the Consent Decree.
Government's Technical Expert:
Cascade Geosciences, Inc., serves as the Government's technical expert for hydrogeological matters. Dr. Patricia Voss, Ph.D., Hydrogeology, is the designated lead technical expert. Cascade Geosciences provides independent technical review of monitoring well network design, groundwater data interpretation, and hydrogeological assessments submitted by Pinnacle Creek on behalf of TMC.
TMC Environmental Health and Safety Lead:
Gareth Linford, Vice President, Environmental Health and Safety, Torchlight Mining Corp., serves as the primary corporate point of contact for all matters related to this Plan and is responsible for ensuring that adequate corporate resources are allocated to support monitoring program implementation.
1.5 Plan Organization
This Plan is organized into the following sections, each serving a distinct function within the overall monitoring program framework:
Section 1 — Introduction and Purpose provides the regulatory and contractual context for the Plan, defines its scope and objectives, identifies the responsible parties, and describes its relationship to other plans and instruments under the Consent Decree.
Section 2 — General Monitoring Program Requirements establishes the overarching monitoring objectives, program duration, and general protocols applicable to all four sites, including sampling methods, laboratory requirements, health and safety provisions, and procedures for modifying the Plan.
Sections 3 through 6 — Site-Specific Monitoring Plans provide detailed monitoring requirements for each of the four Consent Decree sites. Each site-specific section includes a description of the site and its environmental setting, the monitoring well network, and medium-specific monitoring protocols (groundwater, surface water, sediment, soil, air/vapor, and specialized monitoring as applicable). Analyte lists, detection limits, sampling frequencies, and performance standards are specified for each medium at each site.
Section 7 — Quality Assurance and Quality Control (QA/QC) establishes the field and laboratory QA/QC requirements applicable to all monitoring activities under this Plan, including sample collection QA/QC, laboratory analytical QA/QC, data management, and data usability assessment.
Section 8 — Reporting Requirements specifies the content, format, frequency, and distribution of all monitoring reports, including quarterly and annual monitoring reports, exceedance and incident reports, five-year review reports, and reporting to the independent monitor.
Section 9 — Data Evaluation and Statistical Methods describes the statistical methods to be used for trend analysis, comparison to performance standards, evaluation of trigger levels and response actions, and verification of completion criteria.
Section 10 — Plan Modification and Adaptive Management establishes the triggers, processes, and frameworks for modifying the monitoring program in response to changing conditions, and describes the adaptive management approach that will guide ongoing program refinement.
Section 11 — References lists all regulatory standards, guidance documents, and other materials referenced in this Plan.
Appendices A through J provide supporting technical information, including monitoring well construction details, location maps, analyte and detection limit master tables, standard operating procedures, sample designation protocols, consent decree cross-reference tables, regulatory standard comparison tables, chain-of-custody form templates, field data sheet templates, and the certification and signature page.
1.6 Relationship to Other Plans and Instruments
This Plan is one element of an integrated suite of plans, agreements, and financial instruments established under the Consent Decree. The following documents are directly related to and should be read in conjunction with this Plan:
Remediation Plans and Studies:
(a) Ridgecrest Remedial Action Work Plan — to be submitted by TMC no later than December 14, 2025, pursuant to Consent Decree Section 8(a). This work plan will establish site-specific cleanup levels and remedial action objectives for the Ridgecrest Copper-Molybdenum Mine. Groundwater and surface water performance standards referenced in Section 3 of this Plan will be finalized upon approval of the Remedial Action Work Plan and may necessitate modification of this Plan pursuant to Section 10.
(b) Gallatin Corrective Measures Study — to be submitted by TMC no later than June 14, 2026, pursuant to Consent Decree Section 9(b). The CMS will evaluate and recommend corrective measures for the three identified SWMUs and the CS₂ groundwater plume at the Gallatin Chemical Works. Monitoring program adjustments for the Gallatin site may be required following approval of the CMS and selection of a corrective measure.
(c) Bonanza Creek Liner Repair and Containment Plan — commencement of implementation no later than June 14, 2026, pursuant to Consent Decree Section 10(c). This plan will address the documented heap-leach liner failures and establish containment measures to prevent future releases to the ephemeral tributary of the Reese River. The monitoring program for Bonanza Creek described in Section 5 will be coordinated with the implementation schedule for liner repair and containment activities.
(d) Kanawha Bend Interim Stabilization Measures — completion of interim stabilization no later than December 14, 2026, pursuant to Consent Decree Section 11(d). Interim stabilization includes capping of the former waste lagoon, installation of a groundwater containment barrier, and commencement of DNAPL recovery operations. The monitoring program for Kanawha Bend described in Section 6 is designed to support both the interim stabilization phase and the subsequent long-term corrective action.
(e) Consolidated Remediation Milestone Matrix — attached to the Consent Decree as Appendix D, establishing the schedule of milestones for all four sites, including design submission deadlines, construction commencement and completion dates, and monitoring and reporting milestones.
(f) Performance Standards and Completion Criteria Memorandum — attached to the Consent Decree as Appendix B, defining the specific numerical standards, compliance determination methods, and criteria for certification of completion and consent decree termination at each site.
Independent Monitor Agreement:
(g) Independent Monitor Agreement — executed between the United States, the State of Montana, the State of Nevada, the State of West Virginia, TMC, and Verdant Analytics, Inc., dated February 15, 2025. This agreement establishes the authority, responsibilities, and procedures of the independent environmental monitor, including Verdant Analytics' right to receive all monitoring data and reports concurrent with EPA submissions, to conduct split sampling and independent verification sampling, and to prepare quarterly compliance audit reports and annual public compliance reports. The monitoring program established by this Plan is designed to be fully transparent to and auditable by Verdant Analytics.
Financial Assurance Instruments:
(h) Surety Bond No. ISA-ENV-2025-08934 — issued by Ironbark Surety of America, Inc. in the amount of $165,000,000, providing financial assurance for the performance of remediation obligations at all four sites under the Consent Decree. The surety bond is structured to cover the full estimated cost of remediation and monitoring, with annual premium and collateral adjustments based on remaining remediation obligations and monitoring costs.
(i) Remediation Trust Agreement No. LTC-REM-2025-1177 — established with Larchfield Trust Company, N.A. as trustee, in the initial amount of $80,000,000, to fund ongoing remediation and monitoring activities. Trust disbursements are subject to the joint approval of TMC and EPA, with independent monitor verification of completed work prior to disbursement.
This Plan should be interpreted consistently with the foregoing plans and instruments. In the event of any conflict between this Plan and the Consent Decree, the terms of the Consent Decree shall control.
SECTION 2: GENERAL MONITORING PROGRAM REQUIREMENTS
2.1 Monitoring Objectives
The monitoring program established by this Plan is designed to achieve the following objectives, which apply across all four sites unless otherwise specified in the site-specific monitoring sections:
(a) Baseline Characterization and Confirmation. The monitoring program will confirm and, where necessary, refine the baseline characterization of contaminant concentrations in all affected environmental media. Baseline data are essential for establishing the starting point from which contaminant trends will be evaluated and remedial action effectiveness will be assessed. Where existing data are adequate to establish baseline conditions, this Plan relies on historical data collected under prior investigations and regulatory programs. Where additional baseline data are needed — for example, at newly installed monitoring wells or at locations not previously sampled — this Plan provides for an initial round of baseline sampling prior to commencement of remedial construction activities.
(b) Tracking of Contaminant Migration and Attenuation. The monitoring program will track the spatial extent and temporal trends of contaminant plumes in groundwater, surface water, sediment, and soil. By monitoring at upgradient, source area, and downgradient locations at regular intervals, the program will enable identification of changes in plume configuration, assessment of whether contaminants are migrating beyond previously delineated boundaries, and evaluation of whether natural attenuation or engineered treatment processes are reducing contaminant concentrations over time.
(c) Verification of Remedial Action Effectiveness and Compliance with Performance Standards. A primary objective of the monitoring program is to generate the data necessary to verify that remedial actions being implemented at each site are achieving their intended objectives. Monitoring data will be compared to the performance standards and cleanup levels established in the Consent Decree, the Performance Standards and Completion Criteria Memorandum, and site-specific regulatory permits. Compliance or non-compliance with performance standards will be determined in accordance with the statistical methods and comparison protocols described in Section 9 of this Plan.
(d) Early Warning of Remedy Failure or New Releases. The monitoring program incorporates trigger levels and response protocols (Section 9.3) designed to provide early warning of remedy failure, deteriorating conditions, or new contaminant releases. Sentinel monitoring wells located downgradient of source areas and between source areas and sensitive receptors serve as an early warning network. Exceedance of trigger levels will initiate a defined response protocol, including confirmation sampling, investigation, and, where necessary, remedial adjustment.
(e) Support for Completion Certification and Consent Decree Termination. The ultimate objective of the monitoring program is to generate a body of monitoring data sufficient to support certification by TMC and Pinnacle Creek, review by Verdant Analytics, and approval by EPA that remedial actions have achieved the performance standards and completion criteria for each site. Pursuant to the Consent Decree, monitoring must continue for a minimum of five (5) years after completion of all remedial construction at the relevant site before termination of monitoring obligations may be considered.
2.2 Monitoring Program Duration
The duration of the monitoring program at each site corresponds to the remediation obligation period established by the Consent Decree, plus a minimum post-construction completion monitoring period. Table 2-1 summarizes the monitoring program duration for each site.
Table 2-1: Summary of Monitoring Program Duration by Site
The foregoing dates assume an Effective Date of the Consent Decree of June 14, 2025, which is the anticipated date of entry by the Court. If the Effective Date differs from this assumption, all dates shall be adjusted accordingly.
Monitoring will be conducted throughout the entire remediation obligation period at each site, beginning with baseline and pre-construction monitoring and continuing through construction, operation and maintenance of remedial systems, and post-construction long-term monitoring. The specific sampling frequencies for each medium at each site are set forth in the site-specific monitoring sections (Sections 3 through 6) and generally provide for higher-frequency monitoring during the initial years and construction phases, with potential reductions in frequency during later phases upon demonstration of consistent compliance.
Any reduction in monitoring frequency or scope during the post-construction monitoring period, or any termination of monitoring prior to the dates specified in Table 2-1, requires written approval from the relevant EPA Regional Project Coordinator and the independent monitor (Verdant Analytics, Inc.), based on a technical demonstration by TMC and Pinnacle Creek that such reduction or termination is supported by the monitoring data. Material modifications to the monitoring program are subject to the Plan modification procedures described in Section 2.6 and Section 10 of this Plan.
2.3 General Sampling Protocols
All sampling activities conducted under this Plan shall be performed in accordance with the methods and procedures described in this section and in the site-specific monitoring sections (Sections 3 through 6). Detailed standard operating procedures (SOPs) for each sampling method are provided in Appendix D.
2.3.1 Applicable Methods. All environmental sampling and analysis shall be conducted in accordance with EPA SW-846, Test Methods for Evaluating Solid Waste, Physical/Chemical Methods (current edition, including all updates and revisions), and other EPA-approved methods as specified for particular analytes and matrices in the site-specific sections of this Plan. Where a state regulatory agency has specified alternative or supplementary methods in a permit or corrective action order, such methods shall also be used, and any discrepancies between EPA and state methods shall be resolved through consultation with the applicable EPA Regional Project Coordinator.
2.3.2 Groundwater Sampling Procedures. Groundwater samples shall be collected using low-flow (minimal drawdown) sampling techniques in accordance with EPA Region-specific guidance and ASTM Standard D6771 (Standard Practice for Low-Flow Purging and Sampling for Wells and Devices Used for Ground-Water Quality Investigations). Prior to sampling, monitoring wells shall be purged using a low-flow pump (e.g., bladder pump, peristaltic pump, or dedicated submersible pump) at a rate that minimizes drawdown (generally 0.1 to 0.5 liters per minute) while field parameters are monitored continuously. Stabilization of field parameters — pH, specific conductance, temperature, dissolved oxygen (DO), and oxidation-reduction potential (ORP) — shall be achieved before sample collection commences. Stabilization criteria are defined as three consecutive readings within the following tolerances: pH ± 0.1 standard units; specific conductance ± 3%; temperature ± 0.2°C; DO ± 10%; and ORP ± 10 millivolts.
Where low-flow sampling is not feasible (e.g., due to well construction, low yield, or DNAPL conditions), alternative purging and sampling methods may be used with prior EPA approval. At the Kanawha Bend site, dedicated DNAPL recovery wells shall be sampled using interface probes or other methods appropriate for detecting and measuring DNAPL presence and thickness, as described in Section 6.6.
2.3.3 Surface Water Sampling Procedures. Surface water samples shall be collected using grab sampling techniques at the locations specified in the site-specific sections. Where composite samples are required (e.g., for aquatic toxicity testing or flow-weighted averaging), 24-hour composite samples shall be collected using automated sampling equipment. Sampling personnel shall collect samples from mid-stream at approximately mid-depth, or at representative locations as dictated by site conditions and access constraints. Flow measurements shall be recorded at each surface water sampling station using calibrated flow measurement instruments (e.g., current meters, weirs, flumes, or continuous-recording stage-discharge gauges as specified by site).
2.3.4 Soil Sampling Procedures. Soil samples shall be collected using direct-push technology (e.g., Geoprobe), hand augers, or test pit excavation, depending on the depth interval and site conditions. Continuous soil cores shall be collected where subsurface characterization is required, with samples extracted at specified depth intervals using stainless steel or disposable acetate liners. VOC soil samples shall be collected using EPA Method 5035A (closed-system purge-and-trap) to minimize volatilization losses. Soil samples for metals and general chemistry shall be collected as grab samples from specified depth intervals.
2.3.5 Sediment Sampling Procedures. Sediment samples shall be collected from the upper 15 centimeters of substrate (surface sediments) using stainless steel scoops, Ekman dredges, or hand-driven core samplers, as appropriate for the substrate characteristics. Sediment sampling locations are specified in the site-specific sections and are geo-referenced using GPS with sub-meter accuracy.
2.3.6 Air and Vapor Sampling Procedures. Air and vapor sampling methods are specified in the site-specific sections for the Gallatin Chemical Works (sub-slab vapor and indoor air, Section 4.6) and the Kanawha Bend Chemical Plant (ambient fenceline air monitoring, Section 6.7). General protocols include canister sampling (SUMMA canisters for VOCs), sorbent tube sampling, and continuous monitoring using open-path Fourier Transform Infrared (FTIR) spectroscopy.
2.3.7 Field Decontamination Procedures. All non-dedicated sampling equipment shall be decontaminated between sampling locations and between sampling events in accordance with the decontamination SOPs provided in Appendix D. Decontamination generally consists of the following sequential steps: (i) removal of gross contamination with tap water and scrub brush; (ii) wash with non-phosphate laboratory-grade detergent (Alconox or equivalent); (iii) tap water rinse; (iv) deionized water rinse; (v) isopropanol rinse (for VOC sampling equipment only); (vi) final deionized water rinse; and (vii) air dry. Equipment rinsate blanks shall be collected to verify decontamination effectiveness in accordance with the QA/QC requirements of Section 7.
2.3.8 Chain-of-Custody Protocols. Samples shall be maintained under chain-of-custody (COC) control from the time of collection through receipt by the analytical laboratory. A chain-of-custody form shall accompany every sample shipment, documenting sample identification, date and time of collection, collector's name, sample matrix, number of containers, preservatives used, requested analyses, and the continuous chain of custody transfers. Templates for chain-of-custody forms are provided in Appendix H.
2.3.9 Field Documentation. All field activities shall be documented in bound, waterproof field notebooks. Documentation shall include, at a minimum: date, time, and location of sampling; weather conditions; names of sampling personnel; well purge data (volumes, flow rates, field parameter readings); sample identification numbers; observations of unusual conditions (e.g., odors, staining, sheen, turbidity); and any deviations from standard procedures. Photographs shall be taken of sampling activities, site conditions, and any notable observations. All sampling locations shall be recorded using GPS with sub-meter accuracy.
2.3.10 Equipment Calibration. All field instruments — including pH meters, conductivity meters, DO meters, ORP meters, turbidity meters, water level indicators, and flow measurement devices — shall be calibrated in accordance with manufacturer specifications and the calibration SOPs provided in Appendix D. Calibration shall be performed and documented at the beginning of each sampling day and verified at the end of each sampling day. Multi-point calibrations shall be used for pH, conductivity, and DO instruments.
2.3.11 Sample Handling, Preservation, and Holding Times. Samples shall be preserved in the field at the time of collection using the preservatives specified in Table 2-2 and the analytical method-specific requirements. Samples shall be stored in coolers with ice and maintained at 4°C (± 2°C) during transport to the laboratory. Temperature blanks shall be included in each cooler to verify that proper temperature was maintained during transport. Maximum holding times for all analytes are specified in Table 2-2.
Table 2-2: General Sample Preservation and Holding Time Requirements
2.4 Laboratory Requirements
All analytical laboratories performing analyses under this Plan shall meet the following requirements:
(a) Certification. Laboratories shall hold current certification under the applicable state laboratory certification program for the state in which the samples originate (Montana, Nevada, or West Virginia) and/or under the National Environmental Laboratory Accreditation Program (NELAP) for each method and matrix to be analyzed. Current laboratory certifications shall be maintained on file by Pinnacle Creek Environmental and made available to EPA, state agencies, and Verdant Analytics upon request.
(b) Method Detection Limits and Practical Quantitation Limits. Laboratories shall demonstrate the ability to achieve the method detection limits (MDLs) and practical quantitation limits (PQLs) specified in the site-specific analyte tables (Tables 3-2, 4-2, 5-2, and 6-2) and the master tables in Appendix C. Where laboratory-specific MDLs differ from the specified values, the laboratory must demonstrate that its MDLs are at or below the specified values, or TMC must propose alternative MDLs for EPA and Verdant Analytics approval. In no case shall the PQL for any analyte exceed one-half of the applicable cleanup level, performance standard, or regulatory standard for that analyte.
(c) Turnaround Times. For routine monitoring samples, analytical results shall be reported to Pinnacle Creek within twenty-one (21) calendar days of laboratory receipt. For expedited samples (including samples collected in response to exceedance events, incident investigations, or other time-sensitive circumstances), analytical results shall be reported within seventy-two (72) hours of laboratory receipt. Pinnacle Creek shall coordinate with the laboratory in advance of each sampling event to confirm capacity and turnaround time commitments.
(d) Electronic Data Deliverables. Laboratories shall provide electronic data deliverables (EDDs) in EPA-compatible formats, including EQuIS-compatible or equivalent database-ready formats. EDDs shall include, at a minimum: sample identification, laboratory sample number, date sampled, date received, date analyzed, analytical method, analyte name, result, reporting units, MDL, PQL, data qualifiers, and QA/QC results (method blanks, LCS/LCSD, MS/MSD, duplicates, surrogates).
(e) Data Packages. For routine monitoring data (Level II validation), laboratories shall provide standard data packages including case narratives, sample receipt documentation, analytical results, QA/QC summaries, and EDDs. For critical decision-making data requiring Level IV validation (full USEPA Contract Laboratory Program validation), laboratories shall provide complete CLP-type data packages suitable for independent data validation.
2.5 Health and Safety
All field activities conducted under this Plan shall comply with the following health and safety requirements:
(a) Health and Safety Plans. A site-specific Health and Safety Plan (HASP) shall be prepared for each of the four sites prior to commencement of any field activities. Each HASP shall be prepared in accordance with OSHA 29 CFR 1910.120 (Hazardous Waste Operations and Emergency Response, "HAZWOPER") and shall address the specific physical, chemical, and biological hazards present at each site. HASPs shall be prepared by Pinnacle Creek Environmental and reviewed by the TMC EHS department (Gareth Linford, VP EHS).
(b) HAZWOPER Training. All field personnel shall have completed 40-hour HAZWOPER training and current 8-hour annual refresher training in accordance with 29 CFR 1910.120(e). On-site supervisors shall have completed the additional 8-hour supervisor training under 29 CFR 1910.120(e)(4).
(c) Personal Protective Equipment. The HASP for each site shall specify the level of personal protective equipment (PPE) required for each monitoring activity. As a general guideline, groundwater and surface water sampling activities shall be conducted at a minimum of Level D protection (work clothing, safety glasses, hard hat, steel-toed boots, nitrile gloves). Activities involving potential exposure to volatile contaminants (e.g., CS₂ at Gallatin, chlorinated solvents at Kanawha Bend) or DNAPL may require Level C protection (air-purifying respirator in addition to Level D). Upgrade criteria to Level B (supplied-air respirator) shall be specified in the HASP based on air monitoring action levels.
(d) Medical Surveillance. All field personnel shall be enrolled in a medical surveillance program in accordance with 29 CFR 1910.120(f).
(e) Emergency Procedures. Each site-specific HASP shall include emergency response procedures, hospital route maps, emergency contact information, and procedures for medical emergencies, fire, chemical exposure, and severe weather.
2.6 Modifications to the Plan
This Plan is a living document that may require modification over the course of the multi-decade monitoring program. The following procedures govern modifications to this Plan:
(a) EPA and Independent Monitor Approval Required. All modifications to this Plan require written approval from the relevant EPA Regional Project Coordinator (or, for modifications affecting multiple sites, from each affected EPA Regional Project Coordinator) and concurrence from the independent monitor, Verdant Analytics, Inc.
(b) Material Modifications. Modifications that alter the fundamental structure, scope, or requirements of the monitoring program — including changes to monitoring well networks, reduction of analyte lists, reduction of sampling frequency beyond the ranges specified in the site-specific sections, changes to performance standards or cleanup levels, or changes to reporting requirements — are considered material modifications. Material modifications are subject to Court approval and shall be incorporated as amendments to this Appendix via joint stipulation of the parties filed with the Court pursuant to the Consent Decree modification procedures.
(c) Non-Material Modifications. Non-material modifications — such as substitution of equivalent analytical methods, changes to sample container types, corrections to well coordinates, updates to contact information, or other administrative changes that do not affect the substance of the monitoring program — may be approved by EPA and Verdant Analytics without Court approval and shall be documented in the next quarterly monitoring report.
(d) Proposing Modifications. TMC, through Pinnacle Creek Environmental, may propose modifications to this Plan at any time by submitting a written modification request to the relevant EPA Regional Project Coordinator and Verdant Analytics. Modification requests shall include a detailed technical justification for the proposed change, an assessment of the impact on data quality and monitoring program objectives, and a proposed effective date. TMC may also propose modifications in the context of quarterly or annual monitoring reports, where monitoring data support a basis for modification. The procedures for proposing, reviewing, and approving modifications are further described in Section 10.
SECTION 3: RIDGECREST COPPER-MOLYBDENUM MINE — SITE-SPECIFIC MONITORING PLAN
3.1 Site Description and Environmental Setting
The Ridgecrest Copper-Molybdenum Mine ("Ridgecrest" or "the Mine") is located at 14200 Ridgecrest Mine Road, Drummond, Granite County, Montana 59832, approximately 12 miles northwest of the town of Drummond in western Montana. The Mine is owned and operated by Ridgecrest Mine Holdings, LLC, a Montana limited liability company wholly owned by Torchlight Mining (U.S.) Inc.
The Ridgecrest Mine is an open-pit copper-molybdenum mine that was operational from 1978 through December 2019, when mining operations ceased and the facility entered closure and reclamation. The mine footprint covers approximately 3,200 acres and includes the open pit (approximately 650 acres at the surface, with a maximum depth of approximately 1,200 feet below the original ground surface), waste rock dumps totaling approximately 780 acres, a 425-acre tailings impoundment, ore processing facilities (including a concentrator, flotation plant, and solvent extraction/electrowinning circuit), haul roads, and associated infrastructure. The total controlled property, including buffer lands, water rights holdings, and undeveloped parcels surrounding the mine footprint, covers approximately 8,700 acres.
Regulatory Status. The Ridgecrest Mine has been proposed for listing on the National Priorities List (NPL) under CERCLA and is currently addressed under an Administrative Order on Consent (AOC), Docket No. CERCLA-08-2022-0039, executed between EPA Region 8 and Ridgecrest Mine Holdings, LLC on September 15, 2022. The EPA Project Coordinator for the Ridgecrest site is Dr. Samuel Tesfaye, Remedial Project Manager, Superfund and Emergency Management Division, EPA Region 8, Denver, Colorado.
Physiography and Climate. The Mine is situated in the upper Flint Creek watershed in the northern Flint Creek Range of the Rocky Mountains. Site elevations range from approximately 5,200 feet above mean sea level in the lower Flint Creek valley to approximately 7,400 feet at the highest points on the mine property. The climate is semi-arid continental, with average annual precipitation of approximately 14 inches, predominantly as snow from November through March. Average temperatures range from approximately 15°F in January to approximately 70°F in July.
Hydrogeology. The site is underlain by a shallow alluvial aquifer composed of Quaternary alluvium (sands, gravels, and silts) with a thickness ranging from approximately 15 to 80 feet. The alluvial aquifer is the primary shallow groundwater system and is hydraulically connected to Flint Creek. Beneath the alluvium, fractured Cretaceous bedrock (granodiorite and associated intrusive rocks) forms a deeper aquifer with variable hydraulic conductivity controlled by fracture density and orientation. Groundwater flow in the alluvial aquifer is generally toward the northwest, following the Flint Creek drainage. Depth to the water table in the alluvial aquifer ranges from approximately 5 to 25 feet below ground surface, depending on proximity to Flint Creek and seasonal conditions.
Principal Contaminants. The primary environmental concern at the Ridgecrest Mine is acid mine drainage (AMD) generated by the oxidation of sulfide minerals in waste rock and tailings. AMD is characterized by low pH and elevated concentrations of dissolved metals, particularly copper, molybdenum, and selenium. Based on existing site investigation data, the following contaminant concentrations have been documented:
• Dissolved Copper: Average concentration in tailings impoundment seepage of 47 mg/L, compared to the Montana chronic aquatic life standard for copper of 0.0087 mg/L (hardness-dependent). Copper concentrations in alluvial groundwater downgradient of the tailings impoundment range from 0.5 to 28 mg/L.
• Molybdenum: Average concentration of 1.2 mg/L in tailings impoundment seepage, exceeding the EPA health advisory level of 0.04 mg/L for drinking water.
• Selenium: Average concentration of 0.082 mg/L in tailings impoundment seepage, exceeding the MCL of 0.05 mg/L and the Montana chronic aquatic life standard of 0.005 mg/L.
• Sulfate: Average concentration of 3,400 mg/L in tailings impoundment seepage, reflecting the oxidation of sulfide minerals.
Documented seepage from the tailings impoundment has resulted in elevated copper, molybdenum, and selenium concentrations in Flint Creek for a distance of approximately 12 miles downstream of the impoundment. The Flint Creek watershed is the subject of a Supplemental Environmental Project (SEP) — the Flint Creek Watershed Restoration Project — funded under the Consent Decree.
Remediation Cost and Schedule. The negotiated remediation cost for the Ridgecrest Mine is $198.6 million over 30 years (net present value at a 3% discount rate: $134.9 million). Remedy construction is scheduled to commence on June 14, 2027, following approval of the Ridgecrest Remedial Action Work Plan (due December 14, 2025) and completion of remedial design (estimated completion mid-2027). The 30-year remediation obligation extends through June 14, 2055.
3.2 Monitoring Well Network
3.2.1 Existing Monitoring Well Network. The Ridgecrest Mine currently has an existing network of forty-two (42) groundwater monitoring wells, installed between 1998 and 2023 under various phases of site investigation, the AOC, and Montana DEQ requirements. These wells include alluvial aquifer wells screened at depths ranging from 10 to 75 feet below ground surface and bedrock monitoring wells screened at depths ranging from 80 to 350 feet below ground surface. A summary of all existing monitoring wells, including well identification, coordinates, ground surface elevation, total depth, screen interval, well diameter, construction materials, installation date, and drilling method, is provided in Appendix A (Table A-1).
3.2.2 Proposed Additional Monitoring Wells. Based on a review of the existing monitoring network and the monitoring objectives described in Section 2.1, Pinnacle Creek proposes the installation of twenty-four (24) additional monitoring wells to address the following gaps in spatial coverage and depth interval representation:
(a) Upgradient Background Wells (4 wells): Four new alluvial aquifer wells shall be installed upgradient (southeast) of the mine footprint to establish representative background groundwater quality unaffected by mining activities. These wells will be designated RC-MW-043 through RC-MW-046 and will be screened at depths consistent with the shallow alluvial aquifer in the upper Flint Creek valley.
(b) Downgradient Compliance Wells at Tailings Impoundment Perimeter (8 wells): Eight new wells shall be installed along the northern and western perimeters of the tailings impoundment, at intervals of approximately 500 to 800 feet, to establish a comprehensive compliance monitoring boundary. These wells will be designated RC-MW-047 through RC-MW-054 and will include both shallow (alluvial) and intermediate-depth (alluvium-bedrock contact) screen intervals.
(c) Sentinel Wells Along Flint Creek Corridor (6 wells): Six new wells shall be installed along the Flint Creek corridor downstream of the tailings impoundment, at intervals of approximately 2 miles, to provide early warning of contaminant migration toward the creek and to track the attenuation of metal concentrations in groundwater discharging to Flint Creek. These wells will be designated RC-MW-055 through RC-MW-060.
(d) Deep Bedrock Monitoring Wells (4 wells): Four new deep bedrock monitoring wells shall be installed at locations within and adjacent to the mine footprint, targeting fracture zones at depths of 300 to 500 feet below ground surface, to assess the vertical extent of groundwater contamination in the fractured bedrock aquifer. These wells will be designated RC-MW-061 through RC-MW-064.
(e) Pit-Lake Monitoring Points (2 wells/sample points): Two monitoring points shall be established within the open pit for sampling of pit-lake water as the pit fills. These monitoring points (RC-PL-001 and RC-PL-002) may consist of temporary sampling platforms, downhole samplers, or pump-accessible intakes depending on water levels in the pit.
3.2.3 Well Naming Convention. All monitoring wells at the Ridgecrest site shall be designated using the prefix "RC-MW-" followed by a sequential three-digit number (e.g., RC-MW-001 through RC-MW-064). Pit-lake monitoring points shall be designated "RC-PL-001" and "RC-PL-002." Piezometers within the tailings impoundment embankment shall be designated "RC-PZ-001" through RC-PZ-XXX."
3.2.4 Total Proposed Well Count. The total monitoring well network at Ridgecrest, following installation of proposed additional wells, will consist of sixty-six (66) monitoring wells plus two (2) pit-lake monitoring points and the existing piezometer network within the tailings impoundment.