Re-imagining
Mine Waste
Innovative Mine Waste Remediation
Mine waste piles dot the landscape of Leadville. These piles are reminders of Leadville’s rich mining past as well as the environmental problems they generate today. CJK Milling is re-imagining mine waste cleanup. Our Colorado company has developed an innovative approach to remove mine waste, extract minerals for beneficial reuse and then restore the land where the mine waste was located.
Currently in planning and permitting, the operation will be one of the largest, most innovative environmental cleanups of abandoned mine waste ever undertaken in Leadville and could serve as a model for abandoned mine clean-up projects throughout the Colorado high country.
The CJK Milling mine waste remediation process serves as a model for the responsible clean-up and restoration of historic mining districts.
CJK Announces Elimination of Cyanide in Mill Extraction Process.
CJK Milling Company has announced plans to eliminate cyanide from its future metal extraction process at its Leadville, Colorado mill. After listening carefully to community concerns — particularly regarding cyanide — CJK has determined that its existing, fully permitted flotation extraction system is the safest and most responsible path forward. Flotation extraction is a proven, cyanide-free process used in Colorado mining operations for decades. Learn More »
EPA Comments on CJK Project.
"Local entities in Leadville like CJK Milling (CJK) have proposed to reclaim lands to native conditions by removing surface mine ore and waste‑rock piles and reprocessing them at a permitted mill to recover valuable minerals. Proposed source‑removal strategies by private entities — that go above and beyond the existing Superfund site remedies — can reduce the metals entering local watersheds, lessen the burden on water treatment plants over time, and turn idled, mine ore and waste‑rock piles covered land into beneficial use.
The EPA is committed to advancing cleanup and the beneficial reuse of contaminated properties. When landowners propose reprocessing mine ore or waste‑rock piles, the EPA first reviews whether the plan aligns with the selected remedy and documents its evaluation in a property status letter. On November 5, 2025, the EPA issued such a letter to CJK regarding its proposed mine ore and waste‑rock piles reprocessing, finding no apparent inconsistency with the Superfund remedy, advising CJK to obtain any required approvals from state and local agencies and cautioning against activities or structures that could interfere with EPA’s remedial actions.
In short, reusing, repurposing, and recycling the mine ore and waste‑rock piles is a practical, long‑term complement to EPA’s existing remedies. Reprocessing removes contamination at its source, helps protect the watershed, reduces reliance on perpetual water treatment, supports responsible resource recovery, and can return land to productive use. The EPA will continue to coordinate closely with permitting agencies and stakeholders to ensure this work is protective, transparent, and aligned with long‑term cleanup goals."
Linda Kiefer, Project Manager
California Gulch Superfund Site
United States Environmental Protection Agency
Benefits to Leadville and Lake County
Improving water quality at the headwaters of the Arkansas River
Restoring the land to pre-mining, natural conditions
Creating local jobs, and purchasing goods and services for economic growth in the area
Safety and Environmental Protection
CJK Milling is committed to the health and safety of the community and environment.