Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAP• If a sample indicates contamination impacts above background levels for the 15 cm-1 mdepth interval, an additional sample from a depth of 1-2 m will be collected and analyzedfrom that location. This will be repeated, as necessary, until the vertical extent ofcontamination impact is bounded at that location. [contingent]• If the eastern-most ditch sampling point indicates contamination above the surface soilCG w requirement, systematic sampling will continue eastward following the ditch with a30 m spacing until results are below the surface soil CG w .I.9.6Buried Infrastructure Soil SamplingSoils associated with buried infrastructure within WMA 10 will be sampled to determine theircontamination status.• For a minimum of five selected locations along the main storm sewer line within WMA10, excavation will take place to expose the line. These locations will be selected tomaximize the possibility that contamination will be encountered (e.g., locations wherehistorical or current GWS data indicate surface contamination exists). During excavation,exposed soils will be monitored by scans for evidence of elevated gross activity. Thepurpose of this sampling is to evaluate the presence of contamination associated withburied infrastructure. [required]oIf elevated readings are encountered below a depth of 1 m, soils exhibiting thehighest levels of gross activity will be sampled and analyzed.oIf elevated readings are not encountered below a depth of 1 m, a samplerepresentative of soils deeper than 1 m but above the storm sewer line will beobtained.• If contamination above background conditions is encountered at any selected location,trenching will continue to depth until background conditions are observed. An additionalsample will be collected from the base of the trench to verify background conditions. Thepurpose is to vertically bound observed contamination. [contingent]Rev. 1 I-14