Geophysical studies at proposed low-level radioactive waste disposal sites in west Texas

Although the disposal of high-level nuclear waste is officially a national problem, the federal government has charged each state with the responsibility of disposing of its own low-level nuclear waste. Texas has considered many possible areas for its disposal facility, but has studied two sites in Hudspeth County extensively. Geophysical methods have been used to study the subsurface structure of these sites, evaluate the earthquake hazards, and set up monitoring of possible leakage from the sites. The structural studies employed the same techniques as used in petroleum exploration, but with a ore balanced reliance between seismic and potential field methods. Since the scale of these investigations was relatively small (a few miles in extent), high-resolution methodology was employed. This aspect of the project mainly impacted the seismic reflection work. The depth to the bedrock was a major concern because the near-surface alluvium is generally a good natural barrier to any potential leakage. The location of any faults near the sites was also a major concern, because faults were both an indicator of potential earthquake hazards and a possible pathway for rapid movement of any material that might leak from the site. Analysis of the tectonic stability of the site involved regional geophysical data on a crustal scale and an evaluation of the historical earthquake record. A network of seismograph stations was established in the region to monitor contemporary seismicity. Compared to typical petroleum applications of geophysical data, these studies involved a wide variety of data and an analysis that required the methodical integration of these data