Tierra Group completed a siting study to evaluate six potential sites for a paste TSF. Tierra Group prepared civil layouts for each TSF, determining embankment fill volumes, evaluating required diversions for upstream catchment areas, and pipeline corridor layouts.

Tierra Group completed the design for two 3-m upstream raises to an existing paste TSF. The project included a test pit investigation, cone penetration testing, embankment raise and upgradient diversion channel civil design, slope stability analyses, and hydrologic and hydraulic analyses to determine peak flows and the size of stormwater channels and a spillway. Tierra Group prepared an Engineering Design Report, including Issued for Construction (IFC) drawings and technical specifications package to satisfy the Idaho Mine Tailings Impoundment Structures Rules (IDAPA 37.03.05) requirements for proposed TSF raises. Tierra Group also provided permitting support, including preparing a TSF tentative closure plan and a preliminary closure bond estimate.