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Unsaturated fractured rock characterization methods and data sets at the Apache Leap Tuff Site

Description: Performance assessment of high-level nuclear waste containment feasibility requires representative values of parameters as input, including parameter moments, distributional characteristics, and covariance structures between parameters. To meet this need, characterization methods and data sets for interstitial, hydraulic, pneumatic and thermal parameters for a slightly welded fractured tuff at the Apache Leap Tuff Site situated in central Arizona are reported in this document. The data sets include the influence of matric suction on measured parameters. Spatial variability is investigated by sampling along nine boreholes at regular distances. Laboratory parameter estimates for 105 core segments are provided, as well as field estimates centered on the intervals where the core segments were collected. Measurement uncertainty is estimated by repetitively testing control samples. 31 refs., 10 figs., 21 tabs.
Date: August 1, 1990
Creator: Rasmussen, T.C.; Evans, D.D.; Sheets, P.J. & Blanford, J.H.
Partner: UNT Libraries Government Documents Department

Unsaturated zone characterization of the Area 5 Radioactive Waste Management Site

Description: Six undisturbed soil samples of near-surface sediments were collected from the Nevada Test Site (NTS) Radioactive Waste Management Site (RWMS) for physical and hydrologic characterization in the laboratory. Of these samples, three were obtained from the wall of Pit No. 3 and three from the floor. Physical properties measured on all samples were dry bulk density ({rho}{sub b}) and solid particle density ({rho}{sub s}). Average dry bulk densities for the wall and floor samples were 1.47 g/cm{sup 3} and 1.45 g/cm{sup 3}, while solid particle densities were 2.34 g/cc and 2.53 g/cc, respectively. Based on these values, the average porosity for the wall samples was computed to be 0.372 and for the floor samples, 0.427. Moisture content-pressure head relations for each sample were determined using the pressure plate method. The moisture characteristic curves generated from these data have shapes similar to those of a silty sand, with volumetric moisture contents of less than 7% at 33.4 bars. Unsaturated hydraulic conductivity was estimated using the computer model of van Genuchten (1978), which is based on the theoretical developments of Mualem (1976). Results indicate that at near-surface in situ moisture contents, the unsaturated hydraulic conductivity for both wall and floor samples is less than 10{sup {minus}8} cm/sec. 15 refs., 12 figs., 4 tabs.
Date: November 1, 1990
Creator: Daffern, D.D.; Ebeling, L.L. & Cox, W.B.
Partner: UNT Libraries Government Documents Department