History Of Geophysical Studies At The Waste Isolation Pilot Plant (Wipp), Southeastern New Mexico*

A variety of geophysical methods including the spectrum of seismic, electrical, electromagnetic and potential field<br>techniques have used support characterization, monitoring and experimental studies at the Waste Isolation Pilot<br>Plant (WIPP). The geophysical studies have provided significant understanding of the nature of site deformation,<br>tectonics and stability. Geophysical methods have delineated possible brine reservoirs beneath the underground<br>facility and have defined the disturbed rock zone that forms around underground excavations. The role of<br>geophysics in the WIPP project has evolved with the project. The early uses were for site characterization to satisfy<br>site selection criteria or factors. As the regulatory framework for WIPP grew since 1980, the geophysics program<br>was focused on support of experimental and field programs such as Salado hydrogeology and underground room<br>systems and excavations. In summary, the major types of issues that geophysical studies addressed for WIPP are:<br>l Issue I: Site Characterization<br>l Issue 2: Castile Brine Reservoirs<br>l Issue 3: Rustler /Dewey Lake Hydrogeology<br>l Issue 4: Salado Hydrogeology<br>l Issue 5: Excavation Effects<br>The nature of geophysics program for WIPP has been to support investigation rather than being the principal<br>investigation itself The geophysics program has been used to define conceptual models (e.g., the Disturbed Rock<br>Zone-DRZ) or to test conceptual models (e.g., high transmissivity zones in the Rustler Formation). An effect of<br>being a support program is that as new project priorities arose the funding for the geophysics program was limited<br>and withdrawn. An outcome is that much of the geophysics survey information resides in contractor reports since<br>final interpretation reports were not funded.<br>*This work was supported by the United States Department of Energy under contract DE-AC04-94AL85000<br>Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company for the United Sates Department of Energy