NGE-TFT provided field, laboratory, and engineering support to a feasibility-level geotechnical exploration effort for a proposed open-pit gold mine in Livengood, Alaska. Of particular importance to the design evaluation was the need to obtain representative samples of undisturbed permafrost in order to help quantify the nature of the permafrost within the proposed facilities. This was accomplished through the use of refrigerated brine drilling technology, which employed a brine drill mud mixture which was refrigerated onsite to approximately 10°F and then circulated down each exploration core hole to help preserve the permafrost while providing adequate lubrication and cuttings removal. The samples were preserved in a frozen state and delivered to our Anchorage laboratory where extensive thaw strength testing was conducted on the frozen samples.
NGE-TFT conducted a series of coupled thermal/hydraulic transient analyses to model the impact of proposed and existing mine operations on the existing soil and hydraulic conditions. Modeling was conducted using a numerical finite-element analysis software suite input with a database consisting of both measured and theoretical material properties.