KANAWHA BEND CHEMICAL PLANT
INTERIM STABILIZATION MEASURES
Scope of Work and Schedule
Prepared for:
Torchlight Mining Corp. and Torchlight Specialty Chemicals, Inc.
Prepared by:
Pinnacle Creek Environmental, LLC 320 Willowbrook Drive, Suite 100 Bozeman, Montana 59715
Engagement Lead: Dr. Astrid Bergmann, P.E., Senior Principal
In Coordination With:
Calderwood & Harkness LLP Matter No. 1039-00003
Baxter, Tully & Crane PLLC West Virginia Local Counsel
February 18, 2025
CONFIDENTIAL — ATTORNEY-CLIENT PRIVILEGED / ATTORNEY WORK PRODUCT
This document was prepared by Pinnacle Creek Environmental, LLC at the direction of Calderwood & Harkness LLP, outside counsel to Torchlight Mining Corp. and its affiliates, in connection with the matter captioned United States of America and State of Montana v. Torchlight Mining Corp. et al., Civil Action No. 9:24-cv-00087-DWM, U.S. District Court for the District of Montana, Missoula Division. This document is protected by the attorney-client privilege and the work-product doctrine. Disclosure of this document to any person or entity not authorized to receive it does not constitute a waiver of any applicable privilege.
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1. Executive Summary
This document defines the scope, methodology, and schedule for interim stabilization measures ("ISMs") to be implemented at the Kanawha Bend Chemical Plant (the "Site" or "Facility"), located at 2200 Chemical Valley Road, Institute, Kanawha County, West Virginia 25112. The ISMs are required under the consent decree lodged on February 19, 2025, in the matter captioned United States of America and State of Montana v. Torchlight Mining Corp. et al., Civil Action No. 9:24-cv-00087-DWM, pending before the United States District Court for the District of Montana, Missoula Division (the "Consent Decree"). This Scope of Work and Schedule has been prepared by Pinnacle Creek Environmental, LLC ("Pinnacle Creek") at the direction of Calderwood & Harkness LLP, lead outside counsel for Torchlight Mining Corp. ("TMC") and its affiliates, and is intended to guide the planning, execution, and documentation of the ISMs in a manner that satisfies the requirements of the Consent Decree while protecting the ongoing operational capacity of the Facility.
The Kanawha Bend Chemical Plant occupies approximately 78 acres within the Kanawha River valley in the Chemical Valley industrial corridor of Kanawha County, West Virginia. The Facility has been in continuous operation since 1985 and is currently operated by Torchlight Specialty Chemicals, Inc. ("TSC"), a Delaware corporation (EIN: 47-3819204), which is a wholly owned subsidiary of Torchlight Mining (U.S.) Inc. ("TM(US)"), itself a wholly owned subsidiary of TMC. TSC manufactures leaching agents for mining operations and operates a sulfuric acid regeneration unit at the Site. The Facility currently employs approximately 280 personnel and remains an active chemical manufacturing operation.
The Site holds RCRA Permit No. WVD048823915 and has been designated a RCRA Corrective Action facility. The Consent Decree arises from alleged violations of RCRA Sections 3004 and 3005, including the failure to properly close a former surface impoundment and the unpermitted treatment of listed hazardous wastes K062 (spent pickle liquor from steel finishing operations in acid regeneration) and D002 (corrosive waste — sulfuric acid below pH 2.0). The Consent Decree also resolves claims under CERCLA Section 107 for cost recovery of approximately $3.8 million in expenditures incurred by the U.S. Environmental Protection Agency ("EPA") during an emergency response to a sulfuric acid release to a Kanawha River tributary that occurred on June 14, 2020.
The civil penalty allocated to the Kanawha Bend site under the Consent Decree is $3.6 million, which represents a portion of the total $31.5 million civil penalty assessed against TMC across four sites nationwide. The estimated total remediation cost for the Kanawha Bend site over a 20-year remediation period is $38.9 million in nominal dollars, which corresponds to a net present value of approximately $29.0 million at a 3% discount rate.
The ISMs described in this document are designed to control immediate risks to human health and the environment and to prevent further releases of contaminants from the Site while a comprehensive Corrective Measures Study ("CMS") and final remedy are developed and implemented. Specifically, the ISMs address the following conditions at the Site: (i) sulfuric acid residual contamination in near-surface soils with pH values as low as 1.8; (ii) heavy metal contamination (lead up to 4,200 mg/kg and arsenic up to 890 mg/kg) in subsurface soils near the former waste lagoon; (iii) dense non-aqueous phase liquid ("DNAPL") contamination consisting of chlorinated solvents detected in the fractured bedrock aquifer; and (iv) deficiencies in the Site's stormwater management infrastructure that were identified during and following the 2020 EPA emergency response.
The ISMs must be substantially completed by December 14, 2026, which is 18 months after the anticipated Effective Date of June 14, 2025. The ISM Completion Report must be submitted within 30 days of completion, i.e., no later than January 13, 2027. Quarterly progress reports are required throughout the ISM implementation period and must be submitted to EPA Region 3, the West Virginia Department of Environmental Protection ("WV DEP"), the U.S. Department of Justice ("DOJ"), and the court-appointed independent monitor, Verdant Analytics, Inc. (Dr. Kamal Osei, Senior Managing Director).
The West Virginia Department of Environmental Protection is a co-plaintiff in the underlying action. State coordination will be led by Loretta May Hatcher, Assistant Attorney General, West Virginia Attorney General's Office, with local counsel support from Nathan Tully of Baxter, Tully & Crane PLLC, 500 Lee Street East, Suite 1100, Charleston, WV 25301. Mr. Tully will serve as the primary interface for state permitting and regulatory coordination matters.
The total estimated cost for ISM implementation at the Kanawha Bend site is approximately $39.3 million, inclusive of project management, permitting, reporting, and a 5% contingency. This amount encompasses initial capital expenditures and the first approximately two years of operations and maintenance costs for systems installed as part of the ISMs. This estimate is consistent with, and forms the initial phase of, the $38.9 million total site remediation estimate referenced in the Consent Decree, with the understanding that later-phase costs associated with the final remedy will be refined during the CMS process.
2. Site Description and Background
2.1 Site Location and Physical Setting
The Kanawha Bend Chemical Plant is located at 2200 Chemical Valley Road, Institute, Kanawha County, West Virginia 25112. The Site encompasses approximately 78 acres and is situated within the Kanawha River valley, one of the most heavily industrialized corridors in the Appalachian region. The Site is bounded to the north and east by other industrial facilities within the Chemical Valley corridor, to the south by Chemical Valley Road and a mixed-use corridor that transitions into the residential community of Institute, and to the west by undeveloped wooded land that slopes toward a tributary of the Kanawha River. The Kanawha River itself lies approximately 1.3 miles to the northwest of the Site at its closest point.
The topography of the Site is characterized by gently sloping terrain that descends from the eastern portions of the Facility toward the Kanawha River tributary along the western boundary. Elevations across the Site range from approximately 590 feet above mean sea level (AMSL) at the eastern end of the property to approximately 565 feet AMSL near the western property boundary and the tributary drainage.
The regional geology underlying the Site consists of Pennsylvanian-age sedimentary bedrock, primarily sandstone, siltstone, and shale, overlain by Quaternary alluvial deposits. The alluvial overburden varies in thickness from approximately 5 feet along the eastern upland portions of the Site to more than 30 feet in the lower-lying areas adjacent to the tributary. The alluvial deposits consist predominantly of silts, clays, and fine sands with intermittent gravel lenses, and serve as a shallow aquifer that is hydraulically connected to the underlying fractured bedrock aquifer.
The fractured bedrock aquifer beneath the Site is characterized by a complex network of joints, fractures, and bedding-plane partings that serve as the principal pathways for groundwater flow. Regional groundwater flow direction is generally toward the northwest, discharging to the Kanawha River and its tributaries. Hydraulic conductivity values measured in the fractured bedrock during previous site investigations range from approximately 1 × 10⁻⁵ cm/s to 5 × 10⁻³ cm/s, reflecting the heterogeneous nature of the fracture network. Depth to the water table ranges from approximately 8 to 15 feet below ground surface ("bgs"), depending on seasonal conditions and location within the Site.
Adjacent land uses include industrial operations typical of the Chemical Valley corridor to the north and east. The community of Institute, which includes residential neighborhoods, community facilities, and West Virginia State University, lies to the south and southeast of the Site. The proximity of the residential community to the Site is a significant consideration in the design and implementation of the ISMs, particularly with respect to air quality, noise, and community communication.
2.2 Facility Operations
The Kanawha Bend Chemical Plant has been an active chemical manufacturing facility since 1985. The Facility's primary products include leaching agents used in TMC's mining operations at its Ridgecrest and Bonanza Creek mine sites, as well as regenerated sulfuric acid produced through the Facility's acid regeneration process. TSC, the Facility operator, is a wholly owned subsidiary of TM(US), which is in turn a wholly owned subsidiary of TMC. TSC currently employs approximately 280 personnel at the Site, including production operators, maintenance technicians, laboratory analysts, environmental health and safety staff, and administrative support.
The key operational areas of the Facility include:
• Sulfuric Acid Regeneration Unit: Located in the central-eastern portion of the Site, the regeneration unit processes spent sulfuric acid from TMC's mining operations, reconcentrating and purifying the acid for reuse. This unit has been in operation since 1985 and is the primary source area for sulfuric acid residual contamination in adjacent soils.
• Leaching Agent Production Lines: Located in the northern portion of the Site, these production lines manufacture proprietary chemical leaching agents used in mining processes. The production lines occupy approximately 12 acres and include chemical reactors, mixing vessels, and packaging facilities.
• Raw Material Storage: Bulk chemical storage tanks, dry chemical storage buildings, and rail siding facilities are located along the eastern boundary of the Site, adjacent to the CSX rail line that serves the Chemical Valley corridor.
• Product Warehousing: Finished product warehouses and truck loading facilities are located in the northeastern corner of the Site.
• Former Waste Lagoon Area: A former surface impoundment (the "Former Waste Lagoon") occupying approximately 2.3 acres is located in the southwestern portion of the Site, approximately 400 feet east of the Kanawha River tributary. The Former Waste Lagoon received process wastewater and waste residuals from the sulfuric acid regeneration unit and leaching agent production lines from approximately 1985 through 2003, when it was taken out of active service. The Former Waste Lagoon was not properly closed in accordance with RCRA closure requirements, which constitutes one of the violations alleged in the Consent Decree.
• Wastewater Treatment System: An on-site wastewater treatment system processes current operational wastewater streams prior to discharge under the Facility's existing NPDES permit.
2.3 Regulatory History
The Kanawha Bend Chemical Plant has a significant regulatory history that provides essential context for the ISMs described in this document. The following chronology summarizes the key regulatory events:
The Facility was first issued its RCRA Part B permit (Permit No. WVD048823915) by the WV DEP in 1988, authorizing the management of hazardous wastes generated by the sulfuric acid regeneration process and other on-site manufacturing activities. The Facility has operated under successive permit renewals, with the current permit term running through 2028. The Facility was designated a RCRA Corrective Action facility under its permit, obligating TSC to investigate and remediate releases from solid waste management units ("SWMUs") and areas of concern ("AOCs") identified at the Site.
On June 14, 2020, a significant release of sulfuric acid occurred at the Facility when a corroded transfer pipeline ruptured, discharging an estimated 12,000 gallons of concentrated sulfuric acid to the ground surface. A portion of the released acid migrated across the Site's western boundary and entered a tributary of the Kanawha River, resulting in a fish kill and ecological damage along approximately 0.4 miles of the tributary. The release triggered an emergency response by EPA Region 3, which mobilized on-scene coordinators and response contractors to contain and neutralize the acid, stabilize affected soils, and conduct biological assessments. The total cost of the EPA emergency response was approximately $3.8 million, which is the subject of the CERCLA Section 107 cost recovery claim resolved under the Consent Decree.
On September 12, 2023, EPA issued a Notice of Violation ("NOV") to TMC, TSC, and TM(US) covering the Kanawha Bend site together with three other TMC-affiliated facilities: the Ridgecrest Mine Complex (Granite County, Montana), the Gallatin River Processing Facility (Gallatin County, Montana), and the Bonanza Creek Mine (Lincoln County, Montana). The NOV alleged violations of RCRA Sections 3004 and 3005 at the Kanawha Bend site, including the failure to properly close the Former Waste Lagoon in accordance with applicable RCRA closure standards and the unpermitted treatment of listed hazardous wastes K062 and D002 at the Facility.
On January 18, 2024, the United States, acting through the Department of Justice on behalf of EPA, together with the State of Montana, filed a complaint against TMC and its affiliates in the U.S. District Court for the District of Montana, Missoula Division, initiating Civil Action No. 9:24-cv-00087-DWM before the Honorable Donald W. Molloy, Senior United States District Judge. TMC filed its answer on March 5, 2024. Following extensive negotiations, the parties reached a comprehensive settlement, and the proposed Consent Decree was lodged with the Court on February 19, 2025. The Consent Decree is expected to be entered by the Court on or about May 15, 2025, following the requisite public comment period. The Effective Date of the Consent Decree is defined as 30 days after entry, yielding an anticipated Effective Date of June 14, 2025.
2.4 Principal Contaminants of Concern
Based on the results of prior investigations, the following contaminants of concern ("COCs") have been identified at the Kanawha Bend site:
Sulfuric Acid Residuals in Soils. Near-surface and shallow subsurface soils in the vicinity of the sulfuric acid regeneration unit and the perimeter of the Former Waste Lagoon have been significantly impacted by sulfuric acid residuals. Soil pH values as low as 1.8 have been measured in these areas. The acid-impacted soils cover an estimated area of approximately 8.5 acres and extend to depths of up to 12 feet bgs. The low-pH conditions are corrosive, inhibit natural vegetative cover, promote erosion, and cause ongoing leaching of metals and acid to groundwater and surface water. Soils with pH below 2.0 are classified as D002 (corrosive) hazardous waste under RCRA.
Heavy Metals in Subsurface Soils Near the Former Waste Lagoon. Subsurface soil sampling in and around the Former Waste Lagoon has revealed elevated concentrations of lead and arsenic. The maximum detected concentration of lead is 4,200 mg/kg, substantially exceeding the EPA residential soil screening level of 400 mg/kg and the industrial soil screening level of 800 mg/kg. The maximum detected concentration of arsenic is 890 mg/kg, well above the EPA industrial soil screening level of 3 mg/kg for cancer risk and 260 mg/kg for non-cancer risk. These metals are present at depths ranging from 2 to 18 feet bgs within and surrounding the approximate 4.1-acre area encompassing the Former Waste Lagoon footprint and its buffer zone. The heavy metal contamination is attributable to the disposal of process wastes and residuals in the Former Waste Lagoon during its operational period from approximately 1985 to 2003.
Dense Non-Aqueous Phase Liquid (DNAPL). Chlorinated solvents have been detected in the fractured bedrock aquifer beneath the Site. DNAPL — solvent-phase liquid denser than water — has been observed directly in four of twelve bedrock monitoring wells during recent investigations. The chlorinated solvents identified include trichloroethylene ("TCE"), perchloroethylene ("PCE"), and their degradation products cis-1,2-dichloroethylene ("cis-1,2-DCE") and vinyl chloride. The DNAPL source area is estimated to encompass approximately 1.8 acres in the vicinity of the Former Waste Lagoon and the historical chemical storage areas. DNAPL has migrated along preferential fracture pathways to depths of up to 85 feet bgs, significantly complicating extraction and remediation. The presence of DNAPL in fractured bedrock represents one of the most technically challenging aspects of the Site's contamination and is a primary driver of long-term remediation costs and timelines.
Listed Hazardous Wastes. The Facility manages wastes classified under RCRA as K062 (spent pickle liquor generated from steel finishing operations associated with the acid regeneration process) and D002 (corrosive waste — sulfuric acid with pH below 2.0). The improper management and disposal of these wastes, including their historical disposal in the Former Waste Lagoon, is among the RCRA violations alleged in the Consent Decree.
2.5 Previous Investigations and Data Sources
The ISM scope of work described in this document is informed by a substantial body of site characterization data collected over the past several years. The principal data sources include:
• RCRA Facility Investigation (RFI): An RFI was completed under WV DEP oversight in accordance with the terms of the Facility's RCRA Corrective Action permit. The RFI characterized the nature and extent of contamination at identified SWMUs and AOCs, including the Former Waste Lagoon, the sulfuric acid regeneration unit area, and the historical chemical storage areas. The RFI confirmed the presence of the principal COCs described above and delineated the general extent of impacted soils and groundwater.
• EPA Emergency Response Documentation (2020): The EPA's emergency response to the June 2020 sulfuric acid release generated substantial documentation, including analytical data from soil and surface water sampling, biological assessments of the affected tributary, and engineering evaluations of the Facility's containment and stormwater management infrastructure. These data have been incorporated into the ISM planning process and inform, in particular, ISM Element 4 (Surface Water Protection and Stormwater Management Improvements).
• Pinnacle Creek Environmental Phase I and Phase II Environmental Site Assessments (2023–2024): Pinnacle Creek conducted Phase I and Phase II Environmental Site Assessments of the Kanawha Bend site in 2023 and 2024 as part of the broader due diligence and litigation support effort. The Phase II ESA included soil borings, geoprobe investigations, groundwater sampling, and soil vapor surveys that supplemented the RFI data and refined the understanding of contaminant distribution.
• Groundwater Monitoring Data (Quarterly Since 2021): The Facility has conducted quarterly groundwater monitoring at a network of monitoring wells since 2021, in accordance with its RCRA permit and WV DEP directives. This monitoring data provides a baseline understanding of groundwater quality conditions, contaminant concentration trends, and seasonal variations in the water table elevation and flow direction.
• Soil Borings and Geoprobe Investigations (2022–2024): Multiple phases of soil boring and geoprobe sampling have been conducted at the Site to characterize soil conditions in areas of interest, including the acid-impacted soils near the regeneration unit, the heavy metal-impacted soils in and around the Former Waste Lagoon, and the DNAPL source area.
• DNAPL Delineation Study (Pinnacle Creek, 2024): Pinnacle Creek conducted a focused DNAPL delineation study in 2024 to characterize the distribution, mobility, and migration pathways of DNAPL in the fractured bedrock aquifer. This study included advanced fracture characterization techniques (e.g., borehole geophysics, packer testing, DNAPL baildown tests) and provides the basis for the DNAPL containment strategy described in ISM Element 3. A summary of the DNAPL Delineation Study is provided in Appendix D.
3. Regulatory Framework and Consent Decree Requirements
3.1 Applicable Statutes and Regulations
The ISMs at the Kanawha Bend Chemical Plant are governed by and must comply with a comprehensive framework of federal and state environmental statutes and regulations. The principal regulatory authorities applicable to the ISMs include:
Resource Conservation and Recovery Act (RCRA). RCRA Sections 3004 and 3005, codified at 42 U.S.C. §§ 6924 and 6925, establish standards for hazardous waste management and require permits for the treatment, storage, and disposal of hazardous waste. The Kanawha Bend site operates under RCRA Permit No. WVD048823915, which includes corrective action obligations. The ISMs are designed to address conditions at the Site that have been identified as violations of RCRA requirements, including the failure to properly close the Former Waste Lagoon and the unpermitted treatment of listed hazardous wastes K062 and D002. The ISMs must comply with applicable RCRA standards, including land disposal restrictions ("LDRs") promulgated under 40 C.F.R. Part 268 for the management of excavated or treated hazardous waste.
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). CERCLA Section 107, codified at 42 U.S.C. § 9607, provides for cost recovery by the United States for response costs incurred in connection with the release or threatened release of hazardous substances. The Consent Decree resolves EPA's claim for recovery of approximately $3.8 million in costs incurred during the emergency response to the June 2020 sulfuric acid release at the Kanawha Bend site.
West Virginia Hazardous Waste Management Regulations (33 CSR 20). The State of West Virginia has adopted hazardous waste management regulations under 33 CSR 20 that are substantially equivalent to the federal RCRA regulations. These regulations govern the management of hazardous waste at the Kanawha Bend site and impose requirements for permitting, corrective action, and waste management that are implemented and enforced by the WV DEP.
West Virginia Groundwater Protection Regulations. West Virginia's groundwater protection regulations establish standards for groundwater quality and impose requirements for the investigation and remediation of groundwater contamination. The ISMs, particularly ISM Element 3 (DNAPL Containment and Migration Control) and ISM Element 1 (Sulfuric Acid Residual Soil Stabilization), must be designed and implemented in a manner that is consistent with these groundwater protection requirements.
Consent Decree Provisions. The Consent Decree itself establishes specific requirements for the ISMs at the Kanawha Bend site, as described in greater detail in Section 3.2 below. The Consent Decree provisions governing the Kanawha Bend ISMs are set forth in the relevant sections of the Consent Decree addressing remedial obligations for the Kanawha Bend site. Excerpts of the relevant Consent Decree provisions are provided in Appendix H.
3.2 Consent Decree Interim Stabilization Requirements
The Consent Decree defines the scope and objectives of the ISMs for the Kanawha Bend site and establishes mandatory deadlines for their implementation. Specifically, the Consent Decree requires TMC and its affiliates (including TSC) to implement interim stabilization measures that accomplish the following objectives:
(i) Prevent further releases of contaminants to surface water and groundwater from the Kanawha Bend site;
(ii) Stabilize sulfuric acid-impacted soils in the vicinity of the sulfuric acid regeneration unit and the Former Waste Lagoon perimeter to prevent continued acid leaching and soil erosion;
(iii) Contain the migration of DNAPL in the fractured bedrock aquifer to prevent further contaminant transport to downgradient receptors, including the Kanawha River tributary; and
(iv) Address immediate risks from heavy metal contamination in the Former Waste Lagoon area to prevent human exposure and ecological receptor contact.
The Consent Decree establishes a completion deadline of December 14, 2026 for all ISMs at the Kanawha Bend site, which is 18 months after the anticipated Effective Date of June 14, 2025. TMC is required to submit quarterly progress reports documenting the status of ISM implementation to EPA Region 3, the WV DEP, and the court-appointed independent monitor, Verdant Analytics, Inc. The first quarterly progress report is due 90 days after the Effective Date, i.e., by September 12, 2025.
The ISMs are interim in nature and do not constitute the final remedy for the Kanawha Bend site. Following completion of the ISMs, TMC will be required to conduct a comprehensive Corrective Measures Study ("CMS") to evaluate and select a final remedy, followed by a Corrective Measures Implementation ("CMI") phase during which the selected remedy will be designed and constructed. The ISMs are intended to address immediate risks and stabilize site conditions during the period required to complete the CMS and CMI processes.
3.3 Financial Assurance
The Consent Decree requires TMC to maintain financial assurance sufficient to fund the remediation obligations at all four sites addressed by the Consent Decree. The total financial assurance required under the Consent Decree is $245.0 million, which has been established through two instruments:
(a) Surety Bond: Ironbark Surety of America, Inc. has issued a surety bond in the amount of $165.0 million (Bond No. ISA-ENV-2025-08934) guaranteeing TMC's performance of its remediation obligations under the Consent Decree. The bond is secured by a general indemnity agreement and TMC's corporate guaranty. The Ironbark contact for bond-related matters is Thomas Rennick, Vice President, Environmental Surety.
(b) Remediation Trust Fund: TMC has established a remediation trust fund in the amount of $80.0 million at Larchfield Trust Company, N.A. (Trust Agreement No. LTC-REM-2025-1177). The trust fund is held for the benefit of the United States and the State of Montana and may be drawn upon by EPA in the event that TMC fails to perform its remediation obligations. The trust is administered by David Henshaw, Senior Trust Officer, Larchfield Trust Company, N.A.
The Kanawha Bend site's proportional share of the total remediation obligation across all four sites is approximately 11.3%, based on the ratio of the Kanawha Bend estimated remediation cost ($38.9 million nominal) to the total estimated remediation cost for all four sites ($343.5 million nominal). This proportional allocation may be refined as remediation progresses and cost estimates are updated through the CMS process.
3.4 Stipulated Penalties
The Consent Decree includes stipulated penalty provisions that apply in the event of failure to meet ISM deadlines or other performance milestones. The stipulated penalty structure for ISM compliance is as follows:
• For the first 30 days of a violation: $1,500 per day per violation;
• For days 31 through 60 of a violation: $3,000 per day per violation; and
• For any violation continuing beyond 60 days: $5,500 per day per violation.
The stipulated penalties underscore the importance of maintaining schedule compliance throughout the ISM implementation period. Pinnacle Creek has incorporated schedule buffers and contingency planning into the project schedule to mitigate the risk of deadline exceedances, as discussed in Section 9 of this document. However, the potential for significant financial penalties in the event of delay reinforces the need for proactive schedule management, early identification of potential impediments, and timely communication with EPA and the independent monitor regarding any circumstances that may affect the project timeline.
3.5 Independent Monitor Oversight
The Consent Decree provides for the appointment of Verdant Analytics, Inc. ("Verdant"), based in Portland, Oregon, as the court-ordered independent monitor for all four sites addressed by the Consent Decree. Dr. Kamal Osei, Senior Managing Director of Verdant, has been designated as the lead monitor. Dr. Osei and the Verdant team will conduct quarterly compliance audits at each site, including the Kanawha Bend Chemical Plant, to assess TMC's progress in implementing the required interim and final remedial measures.
The independent monitor's responsibilities with respect to the Kanawha Bend ISMs include:
• Reviewing quarterly progress reports submitted by TMC and Pinnacle Creek;
• Conducting quarterly site visits and compliance inspections;
• Evaluating the technical adequacy and progress of ISM implementation activities;
• Preparing annual public reports summarizing the status of compliance at all four sites, including the Kanawha Bend site;
• Reviewing and providing concurrence on the ISM Completion Report; and
• Reporting to the Court on any material non-compliance or concerns regarding the adequacy of ISM implementation.
The estimated cost of the independent monitor's services across all four sites is approximately $4.8 million over a five-year period, or approximately $960,000 per year. These costs are borne by TMC as part of its obligations under the Consent Decree.
4. Interim Stabilization Measures — Scope of Work
4.1 Overview of ISM Components
The ISMs for the Kanawha Bend Chemical Plant consist of four principal work elements, each targeting a specific category of contamination or environmental risk at the Site. These four elements are designed to function together as an integrated interim stabilization program that addresses the most pressing environmental and human health concerns while preserving the flexibility to refine the long-term remediation approach through the subsequent CMS and CMI processes.
The four principal ISM work elements are:
1. ISM Element 1: Sulfuric Acid Residual Soil Stabilization and Neutralization
2. ISM Element 2: Heavy Metal Contaminated Soil Containment and Stabilization (Former Waste Lagoon)
3. ISM Element 3: DNAPL Containment and Migration Control in Fractured Bedrock Aquifer
4. ISM Element 4: Surface Water Protection and Stormwater Management Improvements
All ISM activities will be performed by Pinnacle Creek Environmental, LLC, under the direction of Dr. Astrid Bergmann, P.E., Senior Principal and Engagement Lead. Dr. Bergmann will serve as the Project Director and will be responsible for overall technical direction, quality assurance, and regulatory coordination. ISM implementation will be conducted under the oversight of TSC's Vice President of Environmental Health & Safety, Gareth Linford, who serves as TMC's Project Manager for Kanawha Bend ISM activities. Local counsel coordination with the WV DEP and state regulatory authorities will be managed through Nathan Tully of Baxter, Tully & Crane PLLC.
The following subsections describe each ISM element in detail, including objectives, affected areas, methodology, waste management requirements, and estimated costs.
4.2 ISM Element 1: Sulfuric Acid Residual Soil Stabilization and Neutralization
4.2.1 Objectives. The objectives of ISM Element 1 are to:
• Neutralize acid-impacted soils with pH values as low as 1.8 in the areas adjacent to the sulfuric acid regeneration unit and surrounding the perimeter of the Former Waste Lagoon;
• Prevent the continued leaching of sulfuric acid residuals from these soils to the underlying groundwater and to surface water features, including the Kanawha River tributary;
• Stabilize the acid-impacted soils against erosion and off-site migration of contaminated particulates; and
• Establish a protective engineered soil cover over the neutralized soils to provide long-term containment and support revegetation.
These objectives are consistent with the Consent Decree requirement to stabilize sulfuric acid-impacted soils and prevent further releases of contaminants to surface water and groundwater. ISM Element 1 addresses a source area that has been identified as a continuing contributor to groundwater degradation and that poses direct-contact risks to on-site workers and ecological receptors.
4.2.2 Delineation of Affected Area
Based on the results of prior site investigations, including the Pinnacle Creek Phase II ESA and the RCRA Facility Investigation, the estimated area of acid-impacted soils requiring neutralization and stabilization is approximately 8.5 acres. This area encompasses soils adjacent to the sulfuric acid regeneration unit in the central-eastern portion of the Site and soils along the northern and eastern perimeter of the Former Waste Lagoon.
The depth of acid impact varies across the affected area, ranging from the ground surface to approximately 12 feet bgs, based on data from prior soil borings and geoprobe investigations. The most severely impacted soils (pH < 2.0) are concentrated in the upper 6 feet of the soil profile, with pH values increasing with depth as the acid has been partially attenuated through natural buffering reactions with the alluvial materials.
To confirm and refine the lateral and vertical extent of acid-impacted soils prior to implementation of treatment activities, Pinnacle Creek will advance a minimum of 40 additional soil characterization borings on an approximate 50-foot grid spacing across the 8.5-acre target area. Each boring will be sampled at minimum 2-foot intervals, and soil samples will be analyzed for pH, titratable acidity, and relevant metals. The results of this additional characterization work will be used to finalize the treatment boundaries, determine the volume of soils requiring in-situ versus ex-situ treatment, and optimize the lime application rates for in-situ neutralization.
4.2.3 Methodology. The treatment approach for ISM Element 1 will employ a combination of in-situ neutralization and ex-situ treatment, depending on the severity of acid impact and the depth and accessibility of affected soils:
In-Situ Soil Neutralization. The primary treatment methodology for the majority of the acid-impacted soils will be in-situ neutralization using lime (calcium oxide and/or calcium hydroxide) injection and mechanical mixing. Lime will be applied at rates determined by bench-scale treatability testing, which will establish the optimal lime dosage required to raise soil pH to the target level of pH ≥ 6.0. In-situ neutralization will be accomplished using rotary mixing equipment capable of blending lime reagent into the soil profile to the required treatment depth. For near-surface soils (0 to 4 feet bgs), conventional soil mixing equipment will be used. For deeper soils (4 to 12 feet bgs), deep soil mixing techniques or pressure-injection methods will be employed as appropriate for site-specific conditions.
Excavation and Ex-Situ Treatment. In areas where the soil pH is below 2.0 at concentrations and volumes that preclude effective in-situ treatment — particularly in areas immediately adjacent to the sulfuric acid regeneration unit where direct acid spillage has resulted in highly concentrated acid residuals — excavation and ex-situ treatment will be required. Based on preliminary estimates, approximately 3,500 cubic yards of severely impacted soil will require excavation. Excavated soils will be staged in lined treatment areas on-site and neutralized through controlled lime addition and mechanical mixing. Verification sampling of treated soils will be conducted to confirm achievement of the pH ≥ 6.0 target prior to replacement or off-site disposal.
Verification Sampling. Post-treatment verification sampling will be conducted throughout the treatment area to confirm that the neutralization objectives have been achieved. A systematic sampling program will be implemented on a grid spacing and at depth intervals to be specified in the detailed work plan. Each sample will be analyzed for pH, and a subset of samples will be analyzed for the full suite of COCs to confirm that the neutralization process has not mobilized metals or other contaminants of concern. The performance standard for ISM Element 1 verification is achievement of a soil pH of 6.0 or greater throughout the treated area.
Engineered Soil Cover. Following completion of neutralization activities, the treated soil area will be capped with an engineered soil cover consisting of a minimum 24-inch-thick compacted clay layer overlain by a 6-inch topsoil layer. The topsoil layer will be seeded with a native grass and ground cover mix appropriate for the region and climate conditions to provide erosion protection and long-term vegetative cover. The engineered cover is intended to minimize infiltration of precipitation through the treated soils, reduce the potential for direct human contact, and prevent erosion. Detailed design of the cover system, including specifications for clay compaction, topsoil composition, and seed mix, will be developed during the detailed design phase.
4.2.4 Waste Management
Excavated soils will be characterized under RCRA to determine their regulatory classification. Soils meeting the definition of D002 hazardous waste (corrosivity — pH < 2.0) will be managed in accordance with applicable RCRA hazardous waste management requirements. Treatment of D002 soils on-site through neutralization is expected to decharacterize the waste, rendering it suitable for replacement or disposal as non-hazardous solid waste, subject to verification testing. Soils containing listed hazardous waste K062 (spent pickle liquor constituents) will be managed in accordance with RCRA land disposal restrictions ("LDRs") and the "derived-from" and "mixture" rules. Any soils that cannot be effectively treated on-site to meet applicable LDR treatment standards will be transported to a permitted RCRA Subtitle C treatment, storage, and disposal facility ("TSDF") for off-site management.
All waste management activities will be documented in accordance with RCRA manifest and recordkeeping requirements. A waste management plan specific to ISM Element 1 will be prepared as a component of the detailed work plan and submitted to EPA and the WV DEP for review prior to the commencement of field activities.
4.2.5 Estimated Cost
The estimated cost for ISM Element 1, Sulfuric Acid Residual Soil Stabilization and Neutralization, is summarized as follows:
These cost estimates are based on 2025 unit costs and current market conditions for materials, equipment, and labor in the Charleston, West Virginia metropolitan area. Costs are subject to refinement during the detailed design phase as additional site characterization data become available and the final treatment volumes and methodologies are confirmed.
4.3 ISM Element 2: Heavy Metal Contaminated Soil Containment and Stabilization (Former Waste Lagoon)
4.3.1 Objectives. The objectives of ISM Element 2 are to:
• Contain lead contamination (maximum detected concentration of 4,200 mg/kg) and arsenic contamination (maximum detected concentration of 890 mg/kg) in subsurface soils in and around the Former Waste Lagoon to prevent further migration and exposure;
• Prevent direct human exposure to and ecological receptor contact with metal-contaminated soils;
• Prevent further leaching of metals from contaminated soils to the underlying groundwater; and
• Establish institutional controls and physical access restrictions to manage residual risk during the interim period prior to selection and implementation of a final remedy.
ISM Element 2 addresses one of the most significant source areas at the Site and is designed to provide reliable interim containment of heavy metal contamination while the long-term remedy is developed through the CMS process.
4.3.2 Delineation of Affected Area
The Former Waste Lagoon occupies an approximately 2.3-acre footprint in the southwestern portion of the Site. Soil and groundwater investigations have confirmed that metal contamination extends beyond the lagoon footprint into the surrounding buffer zone, resulting in a total affected area of approximately 4.1 acres. The depth of metal contamination ranges from approximately 2 feet bgs (reflecting the placement of a thin soil cover over the lagoon contents when operations ceased in 2003) to approximately 18 feet bgs.
The highest concentrations of lead and arsenic are found within the Former Waste Lagoon footprint at depths of approximately 4 to 12 feet bgs, corresponding to the zone where waste residuals were historically deposited. Lead concentrations above 3,000 mg/kg and arsenic concentrations above 500 mg/kg have been detected in an area of approximately 0.8 acres within the central portion of the lagoon footprint, which represents the most heavily impacted zone requiring stabilization/solidification treatment.
Additional soil characterization borings will be advanced within and around the Former Waste Lagoon area to refine the delineation of metal contamination prior to the commencement of containment activities. The characterization program will include borings at the proposed cap boundary to confirm that the engineered cap will fully encompass the extent of metal contamination.
4.3.3 Methodology. The containment and stabilization approach for ISM Element 2 combines a multi-layer engineered cap with stabilization/solidification treatment of the most heavily contaminated soils:
Engineered Cap. A multi-layer engineered cap will be constructed over the Former Waste Lagoon area to provide a barrier against infiltration, direct contact, and erosion. The engineered cap will consist of the following layers, from bottom to top:
• Geosynthetic clay liner (GCL): A factory-manufactured GCL will be placed over the prepared subgrade to provide a low-permeability barrier against infiltration. The GCL will be installed in accordance with manufacturer specifications, with seams overlapped and sealed to achieve continuity.
• 40-mil HDPE geomembrane: A high-density polyethylene (HDPE) geomembrane with a minimum thickness of 40 mils will be installed over the GCL to provide an additional barrier against infiltration and contaminant migration. The geomembrane will be factory-fabricated and field-welded at seams, with all seams subjected to destructive and non-destructive testing to verify weld integrity.
• Drainage layer (geocomposite): A geocomposite drainage layer will be placed over the geomembrane to collect and convey any water that infiltrates through the overlying protective soil layer, preventing hydrostatic pressure buildup on the geomembrane. The drainage layer will discharge to a perimeter collection system.
• Protective soil cover (24-inch): A minimum 24-inch-thick protective soil cover will be placed over the drainage layer to protect the underlying barrier layers from mechanical damage, freeze-thaw effects, root penetration, and UV degradation. The protective soil layer will be compacted to specified density requirements.
• Vegetation layer: The surface of the protective soil cover will be seeded with a native vegetation mix to provide erosion protection and long-term surface stability. The vegetation mix will be selected to avoid deep-rooted species that could penetrate the barrier layers.
Stabilization/Solidification (S/S) Treatment. The most heavily contaminated soils within the Former Waste Lagoon — specifically, soils with lead concentrations exceeding 3,000 mg/kg and arsenic concentrations exceeding 500 mg/kg — will be treated in place using stabilization/solidification techniques prior to cap installation. S/S treatment involves the mixing of contaminated soils with Portland cement and proprietary binding agents to physically encapsulate the metal contaminants and reduce their leachability. The estimated volume of soils requiring S/S treatment is approximately 2,100 cubic yards. Bench-scale treatability testing will be conducted using representative soil samples to optimize the S/S mix design and confirm that the treated material meets the applicable performance standards, including Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP) testing to demonstrate reduced leachability.
Institutional Controls. Institutional controls will be established for the Former Waste Lagoon area to restrict future land use and ensure the long-term integrity of the engineered cap. Institutional controls will include:
• Deed restrictions recorded against the property to prohibit ground-disturbing activities within the cap footprint without prior approval from EPA and the WV DEP;
• Access controls, including perimeter fencing with locked gates and warning signage; and
• Requirements for periodic cap integrity inspections and maintenance.
Long-Term Cap Integrity Monitoring Program. A cap integrity monitoring program will be established to ensure the ongoing performance of the engineered cap system. The monitoring program will include:
• Annual visual inspections of the cap surface for evidence of settlement, erosion, animal burrows, vegetation damage, or other conditions that could compromise cap integrity;
• Annual settlement monitoring using survey benchmarks installed at the cap perimeter and within the cap footprint;
• Periodic sampling of the drainage layer discharge to monitor for any indications of contaminant migration through the cap; and
• Maintenance and repair procedures for any deficiencies identified during inspections.
4.3.4 Estimated Cost
The estimated cost for ISM Element 2, Heavy Metal Contaminated Soil Containment and Stabilization, is summarized as follows:
4.4 ISM Element 3: DNAPL Containment and Migration Control in Fractured Bedrock Aquifer
4.4.1 Objectives. The objectives of ISM Element 3 are to:
• Contain the migration of DNAPL (chlorinated solvents) within the fractured bedrock aquifer to prevent further contaminant transport toward downgradient receptors, including the Kanawha River tributary;
• Establish hydraulic control along the downgradient boundary of the DNAPL source zone to stabilize the dissolved-phase contaminant plume and prevent plume expansion;
• Recover measurable DNAPL from bedrock monitoring wells where free-phase product has been observed; and
• Enhance the monitoring well network to improve the understanding of fracture-controlled plume geometry and support the design of long-term remedial measures under the subsequent CMS.
ISM Element 3 is an interim containment measure only. Full remediation of DNAPL in fractured bedrock — which may involve aggressive technologies such as in-situ chemical oxidation ("ISCO"), thermal treatment, or other source-area treatment methods — will be evaluated as part of the CMS. The ISMs are designed to arrest DNAPL migration and stabilize site conditions while the CMS alternatives analysis is completed.
4.4.2 Current Understanding of DNAPL Distribution
The DNAPL contamination at the Kanawha Bend site has been characterized through a series of investigations, culminating in the 2024 Pinnacle Creek DNAPL Delineation Study (Appendix D). The key findings regarding DNAPL distribution are summarized as follows:
DNAPL has been directly observed as solvent-phase liquid in 4 of the 12 existing bedrock monitoring wells at the Site. These four wells (designated MW-BR-03, MW-BR-05, MW-BR-09, and MW-BR-11) are located within and downgradient of the estimated 1.8-acre DNAPL source area in the vicinity of the Former Waste Lagoon and the historical chemical storage areas. Measurable DNAPL thickness ranging from 0.02 feet (a thin sheen) to 0.43 feet has been recorded in these wells, though it is recognized that DNAPL accumulation in monitoring wells may not be representative of the full extent or volume of DNAPL present in the fracture network.
The chlorinated solvents composing the DNAPL have been identified through laboratory analysis as primarily trichloroethylene ("TCE") and perchloroethylene ("PCE"), with degradation products including cis-1,2-dichloroethylene ("cis-1,2-DCE") and vinyl chloride. The dissolved-phase plume associated with the DNAPL source extends approximately 1,200 feet downgradient (northwest) from the source area toward the Kanawha River tributary. Maximum dissolved-phase concentrations in the most heavily impacted wells include TCE at 48,000 µg/L (substantially above the 5 µg/L Maximum Contaminant Level), PCE at 22,000 µg/L (above the 5 µg/L MCL), and vinyl chloride at 340 µg/L (above the 2 µg/L MCL).
Fracture network characterization conducted during the 2024 study identified two dominant fracture sets: a northeast-trending, steeply dipping joint set and a subhorizontal bedding-plane parting system. DNAPL migration has been controlled by these fracture sets, with vertical migration occurring along the steeply dipping joints and lateral spreading occurring along the subhorizontal bedding planes. DNAPL has been detected at depths of up to 85 feet bgs, indicating that it has migrated through multiple bedding-plane partings into deeper portions of the fracture network. This deep penetration of DNAPL into fractured bedrock substantially complicates extraction and is a primary factor driving the need for comprehensive treatment evaluation under the CMS.
4.4.3 Methodology. The DNAPL containment and migration control strategy for ISM Element 3 consists of four integrated components:
Hydraulic Containment. A line of groundwater extraction wells will be installed along the downgradient (northwestern) boundary of the DNAPL source zone to create an inward hydraulic gradient that captures the dissolved-phase contaminant plume and prevents further downgradient migration. A minimum of six extraction wells will be installed, screened across the principal water-bearing fracture zones identified during the fracture characterization study. The extraction wells will be positioned at an approximate spacing of 100 to 150 feet along the downgradient boundary, with exact locations to be determined during detailed design based on the fracture network geometry and hydraulic testing data. Extraction pumping rates will be designed to achieve capture of the dissolved-phase plume under seasonal high-water-table conditions, with capture zone analysis performed using numerical groundwater flow modeling. The target pumping rate for the extraction well system is estimated at 30 to 50 gallons per minute (total system), subject to refinement based on aquifer testing.
Extracted Groundwater Treatment. Groundwater extracted from the containment wells will be treated on-site prior to discharge. The treatment system will consist of a two-stage process: (1) air stripping to remove volatile chlorinated solvents from the extracted water, followed by (2) granular activated carbon ("GAC") adsorption to polish the air stripper effluent and remove residual contaminants to levels that meet applicable discharge standards. The treatment system will be designed to handle the projected flow rates from the extraction well system, with capacity for seasonal variability. Treated effluent will be discharged under an NPDES permit, with discharge monitoring conducted in accordance with permit conditions. Off-gas from the air stripper will be treated using vapor-phase GAC to meet applicable air emission standards. The treatment system will include flow equalization, pH adjustment, and metals removal capabilities as needed to address co-contaminants in the extracted groundwater.
Enhanced Monitoring Well Network. Eight additional bedrock monitoring wells will be installed to supplement the existing 12-well network and improve the delineation of the fracture-controlled contaminant plume. The additional wells will be strategically positioned to: (a) better define the lateral extent of the dissolved-phase plume in the downgradient direction; (b) characterize vertical contaminant distribution within the fracture network; and (c) provide monitoring points between the extraction wells to verify capture zone effectiveness. Each new monitoring well will be constructed with discrete-interval completions to allow sampling at specific fracture zones.
DNAPL Recovery. In the four existing monitoring wells where measurable DNAPL has been observed (MW-BR-03, MW-BR-05, MW-BR-09, and MW-BR-11), DNAPL recovery pumps will be deployed to remove free-phase product as a mass-removal measure. The recovery pumps will be operated on an intermittent basis, with recovery rates monitored and recorded. Recovered DNAPL will be collected, characterized, and managed as hazardous waste in accordance with RCRA requirements. While DNAPL recovery from monitoring wells is not expected to remove a large fraction of the total DNAPL mass present in the fracture network, it represents a readily implementable mass removal measure that can be initiated early in the ISM implementation period while the extraction and treatment system is being designed and constructed.
Interim Measure Limitations. It is important to note that ISM Element 3 is designed as an interim containment measure only. The hydraulic containment system will control the migration of the dissolved-phase plume and prevent further contaminant transport to downgradient receptors, but it will not achieve remediation of the DNAPL source in fractured bedrock. Full DNAPL remediation will require aggressive source-area treatment technologies — such as in-situ chemical oxidation, thermal treatment (e.g., electrical resistance heating or thermal conduction heating), or enhanced bioremediation — that will be evaluated and compared as part of the subsequent CMS. The CMS will include a detailed alternatives analysis, including pilot testing of candidate technologies, to determine the most effective and implementable approach for long-term DNAPL remediation in the fractured bedrock setting at this Site.
4.4.4 Estimated Cost
The estimated cost for ISM Element 3, DNAPL Containment and Migration Control, is summarized as follows:
ISM Element 3 represents the largest single cost component of the ISM program and involves the longest-lead construction activities. The extraction well installation and treatment system construction are on the critical path of the project schedule, as discussed in Section 9.
4.5 ISM Element 4: Surface Water Protection and Stormwater Management Improvements
4.5.1 Objectives. The objectives of ISM Element 4 are to:
• Prevent contaminated stormwater runoff from reaching the Kanawha River tributary by upgrading the Site's stormwater collection and conveyance infrastructure;
• Bring the Site's stormwater management system into compliance with Clean Water Act ("CWA") requirements and NPDES permit conditions;
• Address specific deficiencies in the Site's stormwater management and secondary containment infrastructure that were identified during and following the June 2020 EPA emergency response; and
• Establish a stormwater monitoring program that meets NPDES permit requirements and supports the assessment of ISM effectiveness.
The 2020 sulfuric acid release demonstrated that the Site's existing stormwater management infrastructure was inadequate to prevent the migration of contaminants to surface water during upset conditions. ISM Element 4 is designed to address these deficiencies through targeted infrastructure improvements.
4.5.2 Methodology. The surface water protection and stormwater management improvements under ISM Element 4 will include the following components:
Stormwater Retention Basins. Two lined stormwater retention basins will be constructed along the western boundary of the Site, upstream of the point where stormwater runoff from the Facility drains toward the Kanawha River tributary. The basins will have a combined capacity of approximately 1.2 million gallons and will be designed to capture and hold stormwater runoff from the active production areas, including the sulfuric acid regeneration unit area and the leaching agent production lines. The basins will be lined with a 60-mil HDPE geomembrane to prevent infiltration of potentially contaminated stormwater into the subsurface. Captured stormwater will be tested prior to controlled discharge or, if analytical results indicate the presence of contaminants above discharge standards, routed to the on-site wastewater treatment system for treatment prior to discharge.
Stormwater Conveyance Channel Upgrades. Existing stormwater conveyance channels at the Site will be upgraded with concrete lining to prevent erosion and facilitate efficient conveyance of stormwater to the retention basins. Energy dissipation structures will be installed at key points in the conveyance system to reduce flow velocities and prevent scour. The upgraded conveyance system will be designed to handle the 25-year, 24-hour design storm event, consistent with WV DEP stormwater management requirements.
Secondary Containment Improvements. Secondary containment systems around the active sulfuric acid storage areas and the regeneration unit will be upgraded to provide adequate containment capacity in the event of a release. Existing containment berms and dikes will be inspected, repaired as necessary, and augmented to ensure compliance with RCRA secondary containment requirements (40 C.F.R. § 264.175) and the Facility's Spill Prevention, Control, and Countermeasure ("SPCC") plan. Secondary containment capacity will be verified to meet the requirement for containment of the largest single tank volume plus a sufficient freeboard allowance for precipitation accumulation.
Oil-Water Separators and Sediment Traps. Oil-water separators and sediment traps will be installed at key stormwater discharge points to remove petroleum hydrocarbons, suspended solids, and other conventional pollutants from stormwater prior to entry into the retention basins or discharge to surface water. These treatment devices will be designed and sized based on projected flow rates and pollutant loading at each discharge point.
Stormwater Monitoring. A stormwater monitoring program will be established in accordance with the Facility's NPDES permit requirements. Monitoring will include sampling of stormwater discharges during qualifying storm events, with analysis for the parameters specified in the NPDES permit and any additional parameters identified through consultation with EPA Region 3 and the WV DEP. Monitoring results will be reported in the quarterly progress reports and will be used to assess the effectiveness of the stormwater management improvements.
4.5.3 Estimated Cost
The estimated cost