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SummaryThe seismic design for the Waste Treatment Plant (WTP) on the Hanford Site near Richland, Washington, is based on an extensive probabilistic seismic hazard analysis conducted in 1996 by Geomatrix Consultants, Inc. In 1999, the U.S. Department of Energy Office of River Protection (ORP) approved this design basis following revalidation reviews by British Nuclear Fuels, Ltd., and independent reviews by seismologists from the U.S. Army Corps of Engineers and Lawrence Livermore National Laboratory.In subsequent years, the Defense Nuclear Facilities Safety Board (DNFSB) staff has questioned the assumptions used in developing the seismic design basis, particularly the adequacy of the site geotechnical surveys. The Board also raised questions about the probability of local earthquakes and the adequacy of the "attenuation relationships" that describe how earthquake ground motions change as they are transmitted to the site. The ORP responded with a comprehensive review of the probability of earthquakes and the adequacy of the attenuation relationships. However, the DNFSB remained concerned that "the Hanford ground motion criteria do not appear to be appropriately conservative." Existing sitespecific shear wave velocity data were considered insufficient to reliably use California earthquake response data to directly predict ground motions at the Hanford Site.To address this remaining concern, the ORP provided a detailed plan in August 2004. Key features of this plan included acquiring site-specific soil data down to approximately 500 feet, reanalyzing the effects of deeper layers of sediments interbedded with basalt (down to about 2,000 feet) that may affect the attenuation of earthquake ground motion more than previously assumed, and applying new models for how ground motions attenuate as a function of magnitude and distance at the Hanford Site.This interim report documents the collection of site-specific geologic and geophysical data characterizing the WTP site and the modeling of the WTP site-specific ground motion response.New geophysical data were acquired, analyzed, and interpreted with respect to existing geologic information gathered from other Hanford-related projects in the WTP area. Existing data from deep boreholes were assembled and interpreted to produce a model of the deeper rock layers consisting of interlayered basalts and sedimentary interbeds. These data were analyzed statistically to determine the variability of seismic velocities and then used to randomize the velocity profiles. New information obtained from records of local earthquakes at the Hanford Site was used to constrain site response models. The earthquake ground motion response was simulated on a large number of models resulting from a weighted logic tree approach that addresses the geologic and geophysical uncertainties. Weights were chosen by the working group described in the acknowledgements. Weights were based on the strength or weakness of the available data for each combination of logic tree parameters. Finally, interim design gr...

This data package is a compilation of existing geologic data from the Integrated Disposal Facility Site for use in the 2005 Performance Assessment. The data were compiled from both surface and subsurface geologic sources. The surface mapping has been published previously. The quality and uncertainty of the data are discussed. The 2004 report was modified to include results of studies of the shearwave velocity of sediments at and near the IDF site, which were performed for the Waste Treatment Plant and groundwater monitoring wells 299-E17-26 and 299-E24-24. The conclusions of the original report have not changed with the new data.

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