Sweetwater Mine Permitting

Tierra Group’s Team began work at the Sweetwater mine in 1993 assisting permitting and developing tailings impoundment management strategies for the mine. We successfully designed and installed an innovative internal seal for repair of the mine’s damaged decant discharge conduit. Tierra Group began working at Sweetwater again in 2015 designing a 5 foot TSF dam and spillway raise. Unique design challenges were overcome with a comprehensive field investigation including CPT and hollow stem auger drilling. Liquefaction analyses were performed and incorporated into the upstream raise design. A challenging hydrology model was completed and a raise to the existing spillway was designed. The raise design was approved by MDNR Dam and Reservoir Safety council in March 2016. Construction was completed in early 2017 with support provided with Tierra Group overseeing construction activities and evaluating proposed design changes. An As-Built report was completed in April 2017 conforming to MDNR requirements. Tierra Group provided additional support at Sweetwater by designing a 23 foot dam raise providing more than 15 years additional tailings capacity. A new spillway and saddle dam was included in the design. The dam raise design was approved by MDNR in July 2018. Tierra Group supported dam raise construction in 2021 completing design optimizations that reduced construction costs, supporting construction, and completing an as-built report.