Sagebrush Tablestakes Mine Reclamation, Hydrogeological & Geochemical Studies

Wyoming Department of Environmental Quality
Gas Hills, Wyoming

Wenck was retained by the Wyoming Department of Environmental Quality, Abandoned Mine Land Program to prepare reclamation designs for 250 acres of abandoned uranium mine disturbance in Fremont County, Wyoming. Wenck was responsible for determining surface ownership, the eligibility of disturbances for AML funding, obtaining consents and clearances for investigation, sampling area spoils, developing a hydrologic restoration plan which would create a viable surface water impoundment, evaluating the existing and modeling the post-reclamation ground water potentiometric surface, developing geomorphic guidelines for final reclamation, and developing reclamation options. Subcontractors to Wenck assisted in radiologic surveys, geotechnical investigations, and the determination of spoil/cover soil suitability. 

Initial disturbance in the project area began in the 1950s and continued intermittently through 1979. Disturbance included large surface spoil piles, and one open mine pit with a combination ground and surface water impoundment. The pit occupied 37 acres, while the impoundment occupied 14 acres with highwalls averaging 125 feet.

Three master grading options were prepared along with a cost estimate for the alternatives in the Report of Investigation (ROI). AutoCAD software was used to perform earthwork computation and to develop each of the grading alternatives. Wenck also analyzed the existing and proposed drainage system at the site for the ROI. The decision was made by AML, Wenck, and the Bureau of Land Management to backfill the impoundment as the preferred alternative.

Wenck prepared a master ground water and hydrogeological study. A selective handling plan isolating unsuitable material above the predicted post-reclamation final ground water table in the impoundment area and eliminating the surface radiation hazards was integrated into the final design.

Wenck was also retained to prepare final engineering designs for the construction phase of the project with approximately 1.5 million cubic yards per phase for the six phases. We have completed the design and construction supervision for the final phase (Phase 6), which began in spring 2009. The final reclaimed land surface was developed utilizing the GeoFluve software. This design aid was used to improve the site geomorphology and develop the final drainage network for the reclaimed mine site.

The total reclamation cost is approximately $10 million.

Major Project Features: 

  • Reclamation Design for 250 Acres of Abandoned Uranium Mine Disturbance
  • Hydrogeological and Geochemical Studies
  • Hydrologic Modeling
  • Preparation of Selective Handling Plans
  • Suitable and Unsuitable Material Field Investigations
  • Development of Hydrologic Restoration Plan
  • Construction Management

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