Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAP• Buried infrastructure will be mapped in each WMA (see Sections 5 and 6.12 for moredetails). Particular attention will be paid to buried infrastructure that may have carriedcontaminated liquids and to infrastructure that was installed after 1968. The former is ofconcern from the perspective of a subsurface release, and the latter from the perspectiveof the use of contaminated soils as backfill. Portions of these infrastructure footprints willbe excavated and the adjacent soils screened for the presence of contamination. Ingeneral, for buried infrastructure that carried waste or waste water, the focus will be onsoils immediately beneath the line. For buried infrastructure that did not carry waste orwaste water but was installed after 1968, the focus will be on soils immediately above theline that would be representative of backfill.Characterization of soils adjacent to buried infrastructure will be done by using trenchingtechniques. For buried infrastructure that is active or that potentially contains radioactivecontamination inside, special care will be taken to not compromise the integrity of theinfrastructure.The length, width, and depth of trenches will be dependent on the depth of the buriedinfrastructure that is of interest and the degree of confidence that its location is known.Soils removed while trenching will be staged adjacent to the trench operation andreplaced when the trenching and soil characterization work at a particular location iscomplete to minimize the volume of investigation-derived waste.Gross gamma detectors will be used to assist in the selection of subsurface soil samplesassociated with buried infrastructure that represent potential contamination impactconcerns. Infrastructure that has the potential for radioactive contamination in the lineposes shine concerns for gross gamma detectors once the line is exposed. The possibilityof shine effects will be monitored as necessary and appropriate mitigating actions taken ifnecessary. Examples of actions include collimating the detector being used.• Biased sampling will target WMA-specific features where subsurface contamination issuspected to be present. Areas immediately outside the planned WMA 1 and WMA 2deep excavations are an example (see Section 6.8 for additional details) as is the buriedoriginal outfall ditch in WMA 6 and the original Old Hardstand drainage features inRev. 1 36