Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPE.9.9Decision-Making SummaryA summary of decision-making based on the WMA 5 data is as follows:• For each piece of buried infrastructure of concern that is identified, three biased locationswill be selected, excavation conducted to expose the line, and a soil sample formed fromsoils most likely contaminated. If contamination is encountered above surface soil CG wrequirements, sampling will continue along these lines until it is bounded.• If the GWS identifies a surface soil anomaly that potentially exceeds the surface soilCG emc , that location will be sampled and analyzed.• Biased soil sampling from trenches orthogonal to the western and northern edges of theOld Hardstand. In the event that the initial sampling work does not bound the verticalextent of contamination, soil cores will be extended/vertical trenching continued untilbackground soil conditions are reached.• Systematic subsurface soil sampling will take place on a triangular grid within the zoneof WMA 5 where subsurface soil contamination is a concern. In the event thatcontamination is encountered that is not laterally bounded, the sampling grid will beextended until contamination is laterally bounded.• The WMA 5 surface soil area classification as contained in Figure E.15 will be adjustedbased on GWS results. These adjustments may affect systematic surface sample numberrequirements and will affect the placement of the initial round of systematic surface soilsample locations.• If any 15 cm-1 m soil interval encounters contamination above surface soil CG wrequirements, additional deeper 1-m interval soil samples will be required for thatlocation to determine vertical extent of contamination. If additional vertical samples arerequired, vertical sampling will continue until background conditions are observed.Rev. 1 E-20