Geotechnical, Hydrogeologic and Vegetation Data Package for 200-UW-1 Waste Site Engineered Surface Barrier Design

Abstract

SummaryFluor Hanford (FH) is designing and assessing the performance of engineered barriers for final closure of U-plant waste sites. The ideal barrier will minimize recharge and plant intrusion into the underlying waste, thereby providing protection for human health and the environment. FH is using the Pacific Northwest National Laboratory (PNNL) Subsurface Transport over Multiple Phases (STOMP) simulator as the primary design optimization tool for simulating surface barrier performance. PNNL is supporting FH barrier design activities. One of PNNL's responsibilities is to provide parameter values for the geotechnical, physical, hydraulic, and thermal properties of the materials comprising the barrier and the structural fill on which it will be constructed as well as parameters to allow simulation of plant effects. This report provides the required data package as well as the technical basis, rationale, and methodology used to obtain the parameter values.Best-estimate values for the hydraulic parameters of the soil and geotechnical materials to be used in the performance assessment analyses of the candidate barriers were developed. Hydraulic properties were directly measured for the Environmental Restoration and Disposal Facility spoil pile soils and the silt loam borrow-source soils. Hydraulic properties for the admixture of silt loam and pea gravel and for the silt admixture and quarry spalls were estimated by adjusting the silt-loam parameters for amount of the coarse material. Geotextile hydraulic properties, which were compiled from data reported in the literature. However, properties of the biointrusion layer were derived from the specified particle-size distribution. A summary of Brooks-Corey and van Genuchten parameters along with saturated hydraulic conductivity are presented for each material.Thermal properties also play a critical role in the water and energy balance. These properties were estimated using pedotransfer functions that take into account the mineralogy and water-retention relationships for the porous materials. Predicted properties compared well with literature values, but were generally higher than those reported for Hanford sediments.Plants play an important role in the function of engineered barriers, and accounting for the effects of plants on barrier performance requires a variety of input parameters. Owing to the number of species that may be used to revegetate engineered barriers, plant parameters were grouped on the basis of plant growth forms, e.g., forbs, grasses, and shrubs. Parameters are provided to allow an evaluation of the effects of canopy structure and color, rooting depth, and growth cycle on energy and water balance and ultimately barrier performance.v

Experimental and Numerical Investigations of Soil Desiccation for Vadose Zone Remediation: Report for Fiscal Year 2007

“…Soil thermal properties also play a critical role in the water and energy balance. These properties were estimated using pedotransfer functions that take into account the mineralogy and water-retention relationships of the porous materials (Ward 2007). Some properties were also derived from literature values measured on Hanford sediments (Cass et al 1984;Shannon and Wilson 1994).…”

Hydrogeologic Evaluation of a Ground-Source Cooling System at the BSF/CSF on the Battelle Campus: Final Report

“…Estimates of thermal conductivity and specific heat were based on Hanford Site values reported in the literature (Pruess 2000, Ward 2007. In this analysis, it was assumed that heat transfer was anisotropic because finer grained sediments underlay coarser grained sediments in the Ringold Formation.…”

“…Because no range of thermal parameters were reported in Pruess 2000 andWard 2007, and because initial simulations demonstrated that temperature predictions were not very sensitive to thermal parameter estimates for the Hanford and Ringold formations, a range of thermal parameters was not used. These input parameters, as well as selected hydraulic input parameters, are listed in Table 5.1.…”

Mathematical Formulation Requirements and Specifications for the Process Models

“…Predicting infiltration requires consideration of unsaturated flow processes, precipitation, snow accumulation and melting, surface runoff, water storage, evaporation, transpiration, lateral diversion along sloped layers, and, ultimately, deep percolation (Ward and Gee, 1997;Ward and Keller, 2005). All of these processes occur in response to forcing meteorology that leads to temporal variability in air temperature, relative humidity, wind speed, and barometric pressure and, in the most sophisticated implementations, require the solution of coupled equations for mass and energy transport.…”