American Gypsum Pit Planning and Support

Tierra Group began working at American Gypsum’s Eagle-Gypsum mine located in Gypsum, Colorado in 2014 evaluating haul road improvements. A trade-off study provided a tool for American Gypsum to evaluate safety improvements including alternative haul road alignments and grades, runaway truck ramps, and similar means to reduce risk to haul truck operators. Tierra Group completed long-term pit planning to evaluate current remaining reserves and future potential expansion, which included pit layouts and optimization, waste dump planning, access road/haul route layouts, sediment controls, and surface water management alternatives. Tierra Group has developed preliminary alternatives analyses through scoping-level designs.

Additionally, Tierra Group, teamed with SWCA, completed the engineering design, and prepared a Mine Plan of Operations (MPO) Modification. The MPO modification was prepared to provide an additional 30+ years of mine life. Engineering design included roadway design, open pit planning for a new open pit, hydrologic modeling and hydraulic design, erosion and sediment control evaluations, and stormwater pond design. SWCA completed additional surveys in support of MPO development and acted as the lead for consultation with the Bureau of Land Management.

Sediment Pond Re-Evaluation

Tierra Group updated the existing HEC-HMS models to confirm the spillways can adequately pass flow from the 100-year, 24-hour storm event and to verify that the maximum water surface will be contained within the East and Upper Pits.