Hydraulic Testing in Geothermal Waters with Hydrogen Sulfide Gas, Hycroft Mine, Nevada

The Hycroft Mine (owned and operated by Allied Nevada Gold Corporation) has been conducting groundwater studies to support permitting for a future mine expansion since 2010. The primary objective of the study is to characterize the hydrogeology influencing the proposed mine expansion and quantify groundwater influx to the proposed open pit in order to plan for future active dewatering. SRK Consulting conducted the field investigation and characterization work, which included monitoring well construction in air- and mud-rotary boreholes, isolated corehole packer testing to define hydraulic conductivities across specific fault zones, and installation of corehole piezometers through faults to define potentiometric surfaces. High quality in-situ data were collected, with submersible pressure transducers capable of recording at high temporal frequencies, of pressure, depth to water, and temperature. Isolated packer testing and well constructions were impacted by high temperatures, corrosive fluids, and hydrogen sulfide gas (H2S). However, these were overcome by modifications to the packer system, and through innovative selection of well and piezometer casing materials.