Hydro Geo Chem is a consulting firm that provides the mining industry with support in dewatering and environmental projects. We provide our national and international clientele with expert services in the following areas:

• Permitting and Regulatory Compliance
• Water Resource Development and Water Management Planning
• Wellfield Design for Water Supply, Dewatering, In-Situ Mining, or Remediation
• Solids Characterization for Acid Drainage and Metals Leachability
• Quantification of Pond Seepage and Moisture in Mine Materials
• Predictive Numerical Modeling of Flow and Transport in Saturated and
Unsaturated Media
• Comprehensive Analysis of Chemical Fate and Transport
• Remedial Investigations and Feasibility Studies
• Client Advocacy in Regulatory Negotiations, Public Relations, and Litigation

Specific project experience is listed below.

Trona Mine Dewatering
Hydro Geo Chem evaluated dewatering alternatives for a large, underground trona mine in Wyoming.

Hydroelectric Pump Back Project
High groundwater inflows were encountered during tunnel construction through fractured granitic rocks, requiring expensive dewatering far in excess of that anticipated during project planning.

Evaluation and Impact of Waste Water Handling Practices at a Trona Processing Plant
Waste water handling practices at a trona processing plant had created a brine plume in a fractured bedrock aquifer that discharged into a nearby river.

Reclamation of Acid Mine Water Contamination
A 28-mile-long shoestring alluvial aquifer contains a 7-mile-long plume of metals and acid resulting from seepage from historical mining operations.

Investigation and Design Assistance, Flue Gas Desulfurization Ponds
Several holding ponds, including a 40-acre flue gas desulfurization (FGD) pond, had leaked into aquifers underlying a coal-fired power plant.

Simulation of Groundwater Flow through a Tertiary Fanglomerate Aquifer
Groundwater resources in a tertiary fanglomerate aquifer were potentially affected by remedial groundwater pumping.

Copper Mine and Mill Tailings Characterization and Seepage Analysis
An assessment of the potential groundwater quality impacts of drainage from over 2 square miles of copper mine and mill tailings was required for permitting mine operations.

Other Mining-Related Projects

Chromium Waste Site Evaluation and Cleanup, Arizona WQARF Site
HGC conducted the evaluation and partial cleanup of an Arizona WQARF site. Core-drilling, sampling, and on-site analysis were used to determine the vertical distribution of metals. Environmental tracers were used to evaluate the potential for further contamination migration. Potential migration was also evaluated by simulating the movement of hexavalent chromium through unsaturated soils beneath an unlined disposal pit. The modeling was accomplished using an in-house code called EVUN, which solves the Richard’s equation for unsaturated flow. The simulations were performed to determine any potential impacts in groundwater beneath the site and to evaluate the effectiveness of a cover and capillary barrier on subsurface chromium transport.

We conducted column tests on sample cores from the site, determining the optimum method to chemically reduce the heavy metals to an immobile form. Using these results, we devised and implemented a proprietary in-situ treatment and monitoring program. Finallly, HGC designed and installed a vegetated cover over the site.

Simulation of Groundwater Seepage to a Limestone Quarry, Iowa
HGC preformed numerical simulations of groundwater flow to a limestone quarry in Iowa. Seepage rates into the quarry at various stages of excavation were estimated. In addition, the effect on seepage rates of removing low permeability beds at the base if the quarry were evaluated. Predictions were also made of the effects of dewatering on the local groundwater system. These simulations were performed using a three-dimensional intregrated finite-difference code developed by out staff. Results from these simulations provide management and development guidance for ongoing operations at this quarry.

Impacts of Mining on the Water Resources of the Pueblo of Laguna, New Mexico
HGC evaluated the potential impacts of uranium mining on the water resources of the Pueblo of Laguna. The project area included the San Juan Basin (about one-fifth the area of the state), although the study focused on the southern half of the Basin. The study included preparation of a data collection and interpretation report, design of a water quality monitoring program, and development and calibration of a groundwater flow model of the Basin. Much of the study was dedicated to describing the geology and hydrology of the area, including quantification of the important re-charge, specified flux, and constant head boundaries. Chemical and isotopic data were also used for verification.

Construction and calibration of a numerical model of the Basin resulted in the identification of a fracture-controlled recharge area for the aquifer system. Transient simulations were conducted to determine dewatering effects from different uranium mine development scenarios.


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