Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the disposal of high-level radioactive waste: Part III, Geologic and hydrologic evaluation

Abstract

This report describes the first phase in evaluating the geology and hydrology of the Basin and Range Province for potential suitability of geohydrologic environments for isolation of high-level radioactive waste. The evaluation of the Province applies the guidelines, discussed in Part I (Bedinger, Sargent, and Reed, 1983) of this report to the geologic and hydrologic information compiled for the Province in Part II (Sargent and Bedinger, 1983). The geologic and hydrologic factors considered in the Province evaluation include distribution of potential host rocks, tectonic conditions and data on ground-water hydrology. Potential host media considered include argillaceous rocks, tuff, basaltic rocks, granitic rocks, evaporites, and the unsaturated zone. The tectonic factors considered are Quaternary faults, late Cenozoic volcanics, seismic activity, heat flow, and late Cenozoic rates of vertical uplift. Hydrologic conditions considered include length of flow path from potential host rocks to discharge areas, interbasin and geothermal flow systems and thick unsaturated sections as potential host media. The Basin and Range Province was divided into 12 subprovinces; each subprovince is evaluated separately and prospective areas for further study are identified. About onehalf of the Province appears to have combinations of potential host rocks, tectonic conditions, and ground-water hydrology that merit consideration for further study. The prospective areas for further study in each subprovince are summarized in a brief list of the potentially favorable factors and the issues of concern. Data compiled for the entire Province do not permit a complete evaluation of the favorability for high-level waste isolation. The evaluations here are intended to identify broad regions that contain potential geohydrologic environments containing multiple natural barriers to radionuclide migration.