United States Department of the Navy Geothermal Exploration Leading to Shallow and Intermediate/Deep Drilling at Hawthorne Ammunition Depot, Hawthorne, NV

Abstract

Results of geological, geochemical, and geophysical studies performed by personnel from the Geothermal Program Office (GPO) strongly suggested that there is a geothermal resource beneath lands controlled by the Hawthorne Ammunition Depot. The geothermal fluid is thought to be convecting meteoric water that is derived from precipitation within the Wassuk Range and other nearby mountains. These waters percolate downward through open fractures in the mountain ranges to depths in excess of 7,000 feet. The fluids are then heated deep in the subsurface by the natural geothermal gradient of the area and flow back toward the surface using the Wassuk range-front and associated faults within the bedrock and the sedimentary cover in the southern Walker Lake Valley. Two test holes were sited in 2008 and drilling was completed in March 2009 to depths of 4,000 (HAD -3) feet and 4,700 (HAD- 2A) feet. While data from the holes are still being gathered and analyzed, preliminary results confirm the existence of a moderated temperature anomaly in excess of 217 °F at 1000 feet and 240°F at less than 2500 feet. In addition to drilling, the Navy GPO has contracted the University of Nevada Reno Great Basin for Center for Geothermal Research to conduct additional field exploration at HAD. The tasks required by the Navy range from field mapping and water sampling; detailed mapping, to low angle sun photo interpretations, trenching, to 3-D seismic interpretations and modeling. The Navy recently completed a temperature gradient hole (TGH) drilling campaign. Results suggest multiple resources may exist on HAD lands. To further define the shallow resource, the Navy will drill one or two intermediate to deep geophysical test holes. The results of these shallow holes, synthesized with complimentary geophysical and geological data, will be used to locate and drill one or two intermediate/deep geophysical test holes in late July or early August.