Brazil Millsite


Location

THis project is located on the Trail Creek tributary of Clear Creek, Trail Creek Road, near Idaho Springs.

THis project is located on the Trail Creek tributary of Clear Creek, Trail Creek Road, near Idaho Springs.

Brazil Millsite RUn-on Control Channel being excavated.

Brazil Millsite RUn-on Control Channel being excavated.

Summary

A surface water monitoring program was started in 2006 on Trail Creek to assess metal concentrations and sediment loads related to historical mining. Results showed total concentrations of zinc and copper were significantly greater (by as much as one order of magnitude) during storm runoff events in Trail Creek. Test pits were used at the millsite to determine the depth of the tailings that had historically breached from the upper two tailings ponds. The course of action was to scrape, excavate, and haul the “hot spots” of heavily concentrated metals and place them into the upper ponds, and do a deeper treatment on the remaining tailings in place. All of the abandoned trash and debris from the site was buried in the first of two ponds.

The second pond was regraded to provide some positive drainage away from the site. The tailings piles were amended to stabilize pH and limit the mobility of heavy metals. The tailings piles were then amended with compost to provide a growth media to assist with the revegetation process.

A run-on control channel was constructed along the upgradient side of the millsite. It was constructed to drain off in both directions from a central high point intended to capture clean run-off and overland flow and divert it around the tailings pile.

The objective of the project was to contribute to the reduction of total metal loading in Trail Creek aimed at removing Trail Creek from State of Colorado 303(d) list of impaired waters. 

View the final report as part of the Upper Trail Creek Watershed Project Report, here. View a detailed map of the project location.