Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPE.6 Planned Phase 1 DP ActivitiesFor a more complete description of planned Phase 1 DP activities, see the Phase 1 DP, Section3.1 and Section 7.6.Two WMA 5 structures will remain standing at the initiation of Phase 1 activities: Lag StorageAddition 4 and the Remote-Handled Waste Facility. These structures and all remaining gravelpads, concrete floor slabs, and foundations within WMA 5 will be removed as part of Phase 1activities, including the top two feet of soil beneath hardstands and building pads.E.7 Conceptual Site ModelWMA 5 potentially has impacts from a variety of releases. Some of these impacts are to thesurface, and some are to the subsurface. In addition, historic surface soil reworking throughoutWMA 5 has possibly resulted in subsurface soil contamination. Specifically:• WMA 5 surface soils were affected by the 1968 airborne releases of radioactivity. Theseimpacts originally would have been greatest proximal to the Process Building and wouldhave decreased as one moved north in WMA 5. Since 1968, however, there has beensignificant surface soil reworking throughout much of WMA 5. These activities couldhave removed contaminated soil layers, buried those layers under clean backfill, and/orredistributed/mixed contamination in surface soils. As a result, it is likely thatcontamination, if present, would be isolated and associated with physical features (e.g.,buried infrastructure, building foundations, hardstands, etc.). Consequently, thiscontamination would not necessarily be detectable by surface scanning techniques suchas a gross activity gamma scan. The disposition of potentially contaminated surface soilswithin WMA 5 during the WVDP construction process is not known.• Along with the construction of new facilities within WMA 5 as part of the WVDP, therelikely was the placement of significant amounts of buried infrastructure. Given the fairlyheavy surface soil contamination present at the time of the initiation of the WVDP, it ispossible that backfill used for buried infrastructure is also contaminated at levels thatRev. 1 E-10