Geology of the Waste Treatment Plant Seismic Boreholes

Barnett, D. Brent; Bjornstad, Bruce N.; Fecht, K.R.; Lanigan, David C.; Reidel, Steve P.; Rust, Colleen F.

doi:10.2172/900923

Cited by 3 publications

(7 citation statements)

References 18 publications

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“…A maximum excavation depth of 27 feet is possible. These estimates are different than those reported in Barnett et al (2007) and are documented in email dated April 19, 2007, from Alan Rohay, PNNL, to Tom Brouns, PNNL, and maintained in project files.…”

Section: Sediment Downhole Shear Wave Velocity Measurements In New Bomentioning

confidence: 59%

“…The thicknesses of each basalt and interbed unit from each of the four new boreholes are summarized in Table 6.1. Data presented here are from Barnett et al (2007), with the exception of the C4996 thicknesses of the Cold Creek interbed, Umatilla Member, Mabton interbed, and Priest Rapids Member, Lolo flow. Additional suspension logging data Steller 2007a, 2007b) were compared with geophysical logs used by Barnett et al, and revised upper depths of contact for the Umatilla and Priest Rapids Member, Lolo flow basalts were made.…”

Section: Basalt and Interbed Modelmentioning

confidence: 99%

“…This reduces the transition depth range substantially, to the elevation differences between the contacts in the three different boreholes. Table 6.5 shows the sediment unit thicknesses as reported by Barnett et al (2007). In the seismic site response modeling, layer depths and/or thicknesses are randomized to include the range observed.…”

Section: Averaged Downhole and Seismic Cone Penetrometer Test Shear Wmentioning

confidence: 99%

“…As described in Barnett et al (2007), the Columbia River Basalt Group lava flows consist of a flow top, a dense flow interior, and a flow bottom of variable thicknesses. The flow top is represented by vesicular to rubbly and/or brecciated basalt and may have features and physical properties distinctly different from those of the flow interior.…”

Section: Transitions Zones Between Interbeds and Basalt Unitsmentioning

confidence: 99%

“…Therefore, it is important to distinguish the flow top characteristics, such as density and shear wave velocity, from those of the basalt flow interior and sedimentary interbeds. The approach taken to calculate mean densities for each of the stratigraphic units was to 1) parse the BHGM density data by clearly demarcating each stratigraphic unit using the depths of upper contact from Barnett et al (2007); 2) identify the flow top transition zones using depth of upper contact and measured density values as an indicator; and 3) calculate the mean unit densities for each stratigraphic unit, excluding any measurements from the flow top transition zones.…”

Section: Transitions Zones Between Interbeds and Basalt Unitsmentioning

confidence: 99%

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Site-Specific Velocity and Density Model for the Waste Treatment Plant, Hanford, Washington.

Rohay

Brouns²

2007

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SummaryThe U.S. Department of Energy (DOE) is constructing a Waste Treatment and Immobilization Plant (WTP) to treat and vitrify underground tank waste stored on the Hanford Site in southeastern Washington State. The seismic design basis for the WTP was re-evaluated in 2005, resulting in an increase by up to 40% in the seismic design basis. The original seismic design basis for the WTP was established in 1999 based on a probabilistic seismic hazard analysis completed in 1996. The 2005 analysis was performed by Pacific Northwest National Laboratory (PNNL) to address questions raised by the Defense Nuclear Facilities Safety Board about the assumptions used in developing the original seismic criteria and adequacy of the site geotechnical surveys. The updated seismic response analysis used existing and newly acquired seismic velocity data, statistical analysis, expert elicitation, and ground motion simulation to develop interim design ground motion response spectra that enveloped the remaining uncertainties. The uncertainties in these response spectra were enveloped at approximately the 84th percentile to produce conservative design spectra, which contributed significantly to the increase in the seismic design basis.A key uncertainty identified in the 2005 analysis was the contrasts in velocity between the basalt flows and sedimentary interbeds below the WTP. The velocity structure of the upper four basalt flows (Saddle Mountains Basalt) and the interlayered sedimentary interbeds (Ellensburg Formation) produces strong reductions in modeled earthquake ground motions propagating through them. Uncertainty in the magnitude of velocity contrasts between these basalts and interbeds resulted primarily from an absence of measured shear wave velocities (Vs) in the interbeds. For the 2005 study, Vs in the interbeds was estimated from older, limited compression wave (Vp) data using estimated ranges for the ratio of the two velocities (Vp/Vs) based on analogues in similar materials. A range of possible Vs for the interbeds and basalts was used and produced additional uncertainty in the resulting response spectra.Because of the sensitivity of the calculated response spectra to the velocity contrasts between the basalts and interbedded sediments, DOE initiated the seismic boreholes project (SBP) to emplace additional boreholes at the WTP site and obtain direct Vs measurements and other physical property measurements in these layers. The approach to the SBP involved four main elements: 1) planning and site preparation, 2) new borehole installation, 3) geological and geophysical data collection and analysis, and 4) site seismic response analysis.The three boreholes are within 500 feet of and surrounding the high-level waste vitrification and pretreatment facilities of the WTP, which were the structures affected by the interim design spectra. The core hole is co-located with the borehole closest to those two structures.This report documents the geophysical data collection and analysis element managed and conducted by PNNL. Previousl...

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Section: Sediment Downhole Shear Wave Velocity Measurements In New Bomentioning

confidence: 59%

Section: Basalt and Interbed Modelmentioning

confidence: 99%

Section: Averaged Downhole and Seismic Cone Penetrometer Test Shear Wmentioning

confidence: 99%

Section: Transitions Zones Between Interbeds and Basalt Unitsmentioning

confidence: 99%

Section: Transitions Zones Between Interbeds and Basalt Unitsmentioning

confidence: 99%

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