Holden Mine Site Remediation

Client: Rio Tinto
Lead consultant for long-term compliance and ongoing monitoring at one of the largest former copper mines in the US, including extensive and complex field investigations and support to multifaceted agency negotiations.

Overview of Floyd|Snider Contributions

Development and implementation of regulatory strategy and negotiation support with a multi-agency group
Evaluation of remedial performance and compliance status based on multimedia data collection programs at remote location
Hydrogeologic evaluation and conceptual site model refinement
Comprehensive support for range of agency negotiations
Wetlands delineation and mitigation recommendations in coordination with subconsultants
Remedial alternatives evaluation using numerical groundwater modeling, bench-scale treatability studies, and long-term cost estimates

Project Summary

Rio Tinto is remediating Holden—one of the largest former copper mines in the United States.

The remediation is taking place under a CERCLA Record of Decision (ROD) in cooperation with a multi-agency group led by the U.S. Forest Service, including USEPA, Ecology, and the Confederated Tribes and Bands of the Yakama Nation. The remote 125-acre site, located in the Cascade Mountains and accessible only via Lake Chelan, presents a range of technical and regulatory challenges:

  • Confirmation of the conceptual site model for groundwater–surface water interactions, establishment of points of compliance for protection of surface water and aquatic life
  • Evaluating the performance of Phase 1 of a two-phased remedy to determine the scope of further action required
  • Mitigating wetlands impacts from remedial construction
  • Evaluating potential in situ treatment of soil affected by mine waste rock
  • Operations and maintenance of groundwater recovery and treatment systems and newly capped and revegetated tailings piles

Rio Tinto is remediating Holden—one of the largest former copper mines in the United States. The remediation is taking place under a CERCLA Record of Decision (ROD) in cooperation with a multi-agency group led by the U.S. Forest Service, including USEPA, Ecology, and the Confederated Tribes and Bands of the Yakama Nation. The remote 125-acre site, located in the Cascade Mountains and accessible only via Lake Chelan, presents a range of technical and regulatory challenges:

  • Confirmation of the conceptual site model for groundwater–surface water interactions, establishment of points of compliance for protection of surface water and aquatic life
  • Evaluating the performance of Phase 1 of a two-phased remedy to determine the scope of further action required
  • Mitigating wetlands impacts from remedial construction
  • Evaluating potential in situ treatment of soil affected by mine waste rock
  • Operations and maintenance of groundwater recovery and treatment systems and newly capped and revegetated tailings piles

Our Approach

The Floyd|Snider Team joined the project between the two phases of the ROD remedy with the primary task of assessing the performance of the Phase 1 remedial action, evaluating the necessary steps to meet remaining compliance obligations, and assisting Rio Tinto with a comprehensive regulatory strategy.

The Floyd|Snider Team has undertaken the task of revising and negotiating agency approval of several critical technical documents governing the collection and evaluation of data, site operations, and institutional controls. The Floyd|Snider Team is conducting site-wide data collection and evaluation across media, including surface water, fish, benthic macroinvertebrates, sediment, soil, groundwater, porewater, and seeps, in addition to hydrogeological evaluation and wetlands mitigation assessments. Additionally, the Floyd|Snider Team is using the opportunity provided in the ROD to assist Rio Tinto with evaluation of potential remedial alternatives to a fully penetrating barrier wall for Phase 2, including numerical groundwater modeling simulations, bench-scale treatability studies, and long-term cost estimates.

The Floyd|Snider Team joined the project between the two phases of the ROD remedy with the primary task of assessing the performance of the Phase 1 remedial action, evaluating the necessary steps to meet remaining compliance obligations, and assisting Rio Tinto with a comprehensive regulatory strategy. The Floyd|Snider Team has undertaken the task of revising and negotiating agency approval of several critical technical documents governing the collection and evaluation of data, site operations, and institutional controls. The Floyd|Snider Team is conducting site-wide data collection and evaluation across media, including surface water, fish, benthic macroinvertebrates, sediment, soil, groundwater, porewater, and seeps, in addition to hydrogeological evaluation and wetlands mitigation assessments. Additionally, the Floyd|Snider Team is using the opportunity provided in the ROD to assist Rio Tinto with evaluation of potential remedial alternatives to a fully penetrating barrier wall for Phase 2, including numerical groundwater modeling simulations, bench-scale treatability studies, and long-term cost estimates.

Project Team

Floyd|Snider
Pacific Groundwater Group
CDM Smith
Confluence Environmental Company
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