Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPof 15 cm and analyzed for Cs-137 and Sr-90 via fast-turnaround to confirm their absence, andthen the samples will submitted for off-site analysis for all 18 ROIs. Based on the assumption thatthe analyses confirm background conditions for these soils, the scan data from this area would beused as a point of comparison for scan data collected as part of remedial action support elsewherein the excavations.When excavations have reached their design extent, a second round of remedial support surveyswill be conducted. The second round will begin with complete excavation surface coverage(floors and sloped walls) by using a FIDLER detector. If scan results for any portion of theexcavations indicate evidence of measurable impacts, either additional excavation may take placeor the area of interest will be biased sampled to a depth of 15 cm and submitted for fast turnaroundfor analyses of Cs-137 and Sr-90. If the results indicate soil activity concentrationsexceeding subsurface CG w standards, excavation in that area will continue until scans/samplingindicate the standards have been achieved or the excavation has reached its physical limits.In the case of sloped walls within the WMA 1 or 2 excavations, contamination at levels ofpotential concern may be encountered that extends beyond the practicable limits of excavation,and potentially beyond the sheet pile walls. In these instances soil sampling from the slopedsurface will take place to document the contamination status of soils adjacent to sheet pilingwithin the sloped surface. Additional subsurface soil sampling may take place outside the sheetpiling to determine and document the lateral extent of the observed contamination as part ofPhase 1 activities.If scanning of the exposed excavation surface does not indicate evidence of elevated activity thatwould be a concern and the excavation has reached its design extent, then remedial action surveysoil sampling will take place. Soil samples will be collected systematically on a random-starttriangular grid across the excavation surface (floor and sloped walls) to a depth of 15 cm at adensity of one sample per 200 m 2 . In the case of WMA 1, this will result in approximately 60samples collected from the floor and walls of the excavation. In the case of WMA 2, this willresult in approximately 90 samples from the excavation floor and walls. These samples will besubmitted for quick-turnaround analysis of Sr-90. The results from these samples will be used, inconjunction with the scan information, to determine whether additional excavation is necessary orthe excavation face is ready for FSS data collection following the FSSP protocols. If the latter, theSr-90 sample results will be used to fine-tune FSS sample numbers by providing an estimate ofRev. 1 56