Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAP6.13 Determine Groundwater Flow Data Necessary for WMA 1 and WMA 2 Barrier WallDesignsA significant amount of groundwater flow parameter estimation and modeling work has beenperformed for the Final Environmental Impact Statement and DP and in support of the NorthPlateau Plume Permeable Treatment Wall that was installed in WMA 2 to address the NorthPlateau Groundwater Plume. The results of those data collection and modeling efforts will bereviewed by the contractor responsible for designing the WMA 1 and 2 barrier walls in thecontext of groundwater flow data needs. In the event that additional data are deemed necessary tosupport barrier wall design, wells or piezometers will be installed as necessary and theappropriate tests conducted to fill the data gaps.6.14 Collect Geotechnical Data Required for Barrier Wall DesignThe barrier walls that are planned for the WMA 1 and WMA 2 excavations require geotechnicaldata for proper design. CSAP data collection will provide the information required for the designof the WMA 1 and WMA 2 barrier walls. The strategy for collecting this information and thetypes of information to be collected are as follows:• Soil cores will be collected along the planned footprints of the barrier walls. In the caseof slurry walls, core spacing will be 20 m. In the case of sheet pile walls, core spacingwill be 10 m. The reason for the closer spacing along the sheet pile walls is to provide ahigher level of confidence in the contamination status of soils along the footprint. Corespacing, particularly for the slurry walls, may be modified based on the initial set ofresults. For example, a critical design parameter is the depth to the Lavery Till; if theinitial set of slurry wall core locations shows signs of significant variations in till depthbetween adjacent core locations, the spacing will be tightened.• Intact soil cores will be collected to the extent possible. Cores will include at least 1 m ofthe Lavery Till. Each core will be divided into 1-m segments.• A variety of geotechnical field data will be collected from each core location, asnecessary and required for sheet pile/slurry wall design. In addition, soil samples will beRev. 1 51