In the remote wilderness of Idaho’s Coeur d’Alene National Forest, sits an abandoned historic mine formerly used to extract minerals such as quartz, pyrite, sphalerite and cerussite. Studies by the United States Army Corps of Engineers (USACE) found significant levels of soil contamination from past mining operations, requiring remediation due to its location in the Tributary Creek drainage basin.
Conti Federal safely completed the environmental remediation of the 20-acre Jack Waite Mine site in full compliance with Environmental Protection Agency Region 10 regulatory requirements, procuring required permits and facility certifications prior to groundbreaking. The site consisted of several abandoned mine adits, a shaft, four tailings impoundments and scattered areas of discarded material and debris. The team excavated, tested and removed hazardous waste including arsenic, cadmium, copper, lead, mercury and zinc.
Because of the remote location, efficient logistics were deployed, such as naming conventions and traffic protocols for construction roads and two-way radio communication for employees. Work was performed in challenging site conditions, on mountainsides with limited large truck access and working from camps on site, to meet an aggressive schedule and avoid snow seasons.
Key features of the project included:
In this image: The USACE Seattle team on-site.
In this image: Riprap was placed to protect the soil from erosion.
In this image: After being crushed, the mined materials are separated into various grades and sorted by particle size.
In this image: Preparing the surface before placing the HDPE layer.
In this image: An extra layer of geonet was laid to prevent seepage.
In this image: 650,000 square feet of HDPE liner and geo-composite was placed.
In this image: The project was supported by a number of local and federal agencies.
This project received an Award of Merit from Engineering News-Record magazine. Conti Federal was also recognized by USACE Seattle with the Commander’s Coin for Excellence and by the Coeur d’Alene Trust.