Pend Oreille Mine closure
The Pend Oreille Mine, located in northeast Washington approximately two miles north of Metaline Falls, began underground mining for lead and zinc in 1952. The mine operated intermittently and was closed for decades before Teck Washington Inc. reopened it in 2004.
The mine ceased active operations in 2019. In April 2021, Teck announced a transition from care and maintenance status to closure. The formal closure of the Pend Oreille Mine requires close work between us and Teck to ensure all regulatory requirements are met, and the community is informed of the process.
Waste at Pend Oreille Mine
After metals are extracted from processed ore, a fine material called tailings remains. Prior to Teck’s ownership, and until 1967, the Pend Oreille Mine’s tailings were directly discharged to the Pend Oreille River. After 1967, three tailings disposal facilities (TDFs) were used for tailings disposal from the Pend Oreille Mine. The three TDFs are referred to as TDF-1, TDF-2, and TDF-3.
TDF-1 was used from 1967 – 1974 and is approximately 18 acres. TDF-2 was used from 1974 – 1975 and is approximately nine acres. The original TDF-3 was used from 1975 until mine closure in 1977 and is approximately 20 acres.
After the mine was purchased by Teck, to prepare for resumption of operations in 2004, the company constructed a new tailings disposal facility over TDF-3. Before Teck could resume operations at the mine, an Environmental Impact Statement was completed to analyze potential environmental impacts.
In 2005, Teck entered into a legal agreement with us that required them to conduct a supplemental remedial investigation and feasibility study (RIFS) into the two TDFs no longer in use — TDF-1 and TDF-2.
The RIFS identified contaminants in groundwater and soil around the two TDFs. As a result of the study, a cleanup action plan was required to protect the Pend Oreille River and local streams. Drinking water was not found to be affected by site-related contaminants. Teck began the cleanup process in 2011.
While the mine was in operation from 2004 to 2009, Teck used the new TDF-3 for tailings disposal. TDF-3 was not included in the 2011 cleanup plan and was designed to accept tailings for several decades of mine operations. Plans for the disposition of the new TDF-3 are required as part of the plan for the permanent closure of the mine.
A State Environmental Policy Act (SEPA) checklist was prepared to cover closure elements that were either not covered in the prior FEIS or where the current mine closure plans differ materially from those described in the 2000 FEIS and the 2009 Reclamation Plan. No additional plans for future additions, expansion, or further activities are anticipated beyond the described mine-closure activities.
The SEPA checklist focused analysis on the following key elements where adjustments to the original closure plan warranted additional evaluation:
- Obtaining a State Waste Discharge permit for the treatment of water that has collected in TDF-3 and discharge of that treated water to the underground mine workings.
- Obtaining an amendment to the Conditional Exemption for TDF-3 that would allow the disposal of additional on-site materials to be used as fill in TDF-3 prior to installation of a cap and permanent closure.
- Voluntary Cleanup Program oversight of cleanup of contaminated areas under Washington’s Model Toxics Control Act, which may include the historic debris field, historic gun range, roadways, and parking areas at the site.
Learn more about Teck's closure plans: