PACIFIC NORTHWEST LABORATORY and plant type and distribution. Models used f o r recharge calculati ons shoul d correctly incorporate measured hydraul i c conductivities , evapotranspiration rates, and effects of soil variabil i ty (1 ayeri ng, etc.) t o correctly predict recharge rates a t a given s i t e. Tests of model performance should be conducted over the next several years using data s e t s t h a t contain these inputs.
WaterRetention Data forConcrete. Values at zero matricpotential were calculated using weights of supposedly saturatedsamples.
[1] A modified steady state head control method was used to obtain, on identical samples, direct measurements of soil moisture retention (volumetric water content q versus matric potential y) and unsaturated hydraulic conductivity (K ) as a function of both q and y. The minimum y values for the undisturbed coarse-textured samples were as low as À400 cm, whereas the q values were as low as 0.04. Of the 79 samples, 41 contained a high gravel fraction (>2 mm size) that ranged from 20 to 71% by weight. The remaining samples were sandy with very little gravel fraction. We examined similarities and differences between the two soil types in their retention and K(q) slopes for the intermediate moisture regime. The retention data for the gravelly soils fell within a narrower range than for the sandy type. The water capacity (dq/dy) estimates for the two soil types showed similar variability. Although both soils are coarse-textured, important differences were noted in two integral measures for y(q) and K(q) measurements. The mean and variance for the Campbell pore-size distribution parameter (b) and K(q) slope (b) estimates for the gravelly type were larger than those for the sandy type. A unique relation was noted between b and b; the relationship was similar for the two soil types with a very dissimilar particle-size distribution.
SummaryFor more than 50 years, contaminants from nuclear weapons production were released to the ground at Hanford, Washington. During operations, liquid and solid waste was disposed to the ground, where the contaminants could then move through the unsaturated sediment and into the groundwater. Once in the groundwater, the contaminants are transported with the groundwater that may be withdrawn at wells or discharged to the Columbia River. To predict contaminant release to groundwater, it is necessary to understand the hydraulic properties of the material between the release point and the water table. Measurements of the hydraulic properties of the Hanford unsaturated sediment that buffers the water table are available for many areas of the site; however, the documentation is not well cataloged nor is it easily accessible. The purpose of this report is to identify what data is available for characterization of the unsaturated hydraulic properties at Hanford and where it can be found.This report is arranged into five sections and four appendices. Chapter 1 contains the purpose of this report, identifies other data compilations that are relevant to unsaturated flow issues, and identifies key points of contact at Hanford contractors who are involved with resolution of unsaturated flow issues. Chapter 2 is a brief overview of the soil physics approach and topics of consideration at Hanford. Chapter 3 identifies laboratory and field measurement facilities where Hanford unsaturated flow data is collected. The information in this section includes the hydraulic properties measured and the operational status of each facility. Chapter 4 describes how the references in Appendix B are organized. Chapter 5 contains the conclusion statement. This last section is a discussion of the preceding sections and the appendices and identifies where documentation and other information resides. The four appendices include a list of hydraulic parameters and references to literature sources that are relevant to each category (Appendix A), a bibliography of Hanford related documents with content summaries (Appendix B), a table of sites that have measured data and the number of measurements by parameters type (Appendix C), and a list of the primary references (Appendix D) sorted by year of publication.v
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