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Holden Mine - CERCLA Remedial Design/Remedial Action

Engineering a world-class mine reclamation project

  • 50

    Hectare Site

  • 1.4M

    Stream Restoration

  • 8K

    Lt/Min WTP

  • Washington State

    Washington State

Conceiving an integrated system of mine-closure components at a large copper mine in Washington

Located in north-central Washington State in a remote area of the Okanogan-Wenatchee National Forest, the Holden Mine was one of the largest copper mines operating in the US between 1937 and 1957. Producing over 90,000 tons of copper in its lifetime, the Holden Mine employed 62 miles of underground tunnels and left about 300,000 cubic meters of waste rock and 8.5 million tons of mill tailings covering 50 hectares of US National Forest land.

Our team was brought on to develop the detailed engineering design and remediate environmental problems at the mine. The multi-year, $200M+ mine reclamation project was one of the larger cleanup sites in the State of Washington and required a high level of expertise in mine remediation. We conceived an integrated system of mine-closure components, including infrastructure improvements, groundwater collection and treatment, demolition, and a restoration approach to re-establish vegetation consistent with that of the surrounding forest.

Our team also helped by providing on-site quality assurance and oversight during the remedial action. Now, the Holden Mine lands and the adjacent forest can start the healing process, growing towards a greener future in Washington. 

Meet Our Team

Phillip Crouse, Principal

My goal is to continue my family’s tradition in construction of providing reliable and economic infrastructure for the benefit of the customers and communities I serve.

Kelly Davenport, Stakeholder Engagement & Communications Consultant

I help our clients, stakeholders, communities and the public quickly understand the issues and how we intend to resolve them successfully.
Kelly Davenport Stakeholder Engagement & Communications Consultant Read More

Daniel Dupon, Technical Leader, Mine Water Treatment

The best part about this work is overcoming a good challenge.
Daniel Dupon Technical Leader, Mine Water Treatment Read More

Alexander Edstrom, Civil Engineer

I feel the burden of mining’s history, but also understand its role in building the world we want to see.

James Obermeyer, Senior Vice President

The neat thing about dam engineering is that every site is different and has its own unique set of conditions. It makes the work extremely interesting.

Dave Richardson, Manager, Engineering

I take a lot of personal enjoyment from the opportunity to listen to our clients and translate their needs into a fully-developed plan.

Christine Weber, Senior Associate, Power & Dams

I’m immensely pleased when our hard-earned knowledge and experience lead to elegant solutions for complex dam designs and dam safety issues.
Christine Weber Senior Associate, Power & Dams Read More

Phillip Crouse


Kelly Davenport

Stakeholder Engagement & Communications Consultant

Daniel Dupon

Technical Leader, Mine Water Treatment

Alexander Edstrom

Civil Engineer

James  Obermeyer

Senior Vice President

Dave Richardson

Manager, Engineering

Christine Weber

Senior Associate, Power & Dams

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