Bayhorse Mining District State Park
Environmental Cleanup and Development
Challis, Idaho

The Bayhorse Mining District was one of the first mining discoveries in Idaho in the 1860s and contains a well-preserved ghost town, striking terrain, and unique view into Idaho’s mining history and legacy. Idaho Parks and Recreation (IDPR) engaged TerraGraphics to complete a site investigation, risk management plan, remedial design, and construction oversight for the conversion of the Bayhorse Mine into a historical, cultural, and adventure recreation park.

TerraGraphics collected hundreds of samples throughout the site and utilized XRF and wet chemistry to determine lead and arsenic soil concentrations. Data was used to complete a risk assessment from exposure to lead and arsenic. TerraGraphics conducted a human health assessment and designed a combined risk management/cleanup plan for human health. The risk management plan summarized various exposure management strategies to minimize on-site risk including cleanup, access controls, institutional controls, education/warnings, training, and personal protection. TerraGraphics also provided technical assistance to IDPR to secure three Brownfields cleanup grants for the Townsite and Beardsley-Excelsior and Pacific Mines.

As part of IDPR’s Brownfields grant requirements, TerraGraphics designed the site cleanup and park elements including protective access trails, mine tailings pile cover system, slag pile closure, stream bank enhancement, contaminated soils excavation and disposal. A bid package was prepared and advertised through the Idaho State procurement process for local contractors to bid. Construction of the cleanup and park features started in summer 2008. Cleanup design for additional areas is currently underway.