Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPOne sample will be selected downstream from the confluence of Erdman Brook andFranks Creek, but within the WVDP premises, that is expected, based on GWS results, torepresent the heaviest sediment contamination. This sample will represent a depth of 0 –15 cm and will be analyzed for the 18 ROIs plus the 12 potential ROIs.• Systematic sampling locations will be distributed along Erdman Brook and Franks Creekfor those portions where the sediment CG requirements apply and there is a possibility ofcontamination exceeding sediment CG w requirements. Systematic samples will becollected from the stream center-line. A minimum of three sample locations will beidentified for each portion of the creeks that meet the above criteria, with a systematicsample location spacing of 30 m. Based on current information, only a portion of ErdmanBrook is expected to require this sampling (see Appendix J). Samples will berepresentative of the 0- to 15-cm depth interval under the assumption that ifcontamination is present, it is most likely confined to surface sediments. The sampleresults will be used to determine whether sediment contamination potentially exceedssediment CG w requirements. If any sample yields results above background conditions, asecond sample will be analyzed from that location representative of a 15-cm to 1-m depthinterval. If that sample yields a result above background conditions, a third sample willbe analyzed representative of a 1- to 2-m depth interval. This process will continue untilthe vertical extent of contamination impacts above background is bounded.• Biased and systematic samples will be analyzed for all 18 ROIs. Biased samples will alsobe analyzed for the 12 potential ROIs. If any of these 12 is present at potentiallysignificant levels, the balance of sediment samples will also be analyzed for thoseradionuclides of potential interest that were observed at potentially significant levels.6.8 Define Required Extent of WMA 1 and 2 ExcavationsTwo deep, extensive excavations are planned for WMA 1 and WMA 2 as part of Phase 1decommissioning activities. The excavations will extend, at minimum, 1 ft into the underlyingLavery Till. The lateral extent is to some degree fixed by structure constraints. A minimum extentis required to safely remove buried foundations associated with the Process Building. Likewise,the footprint and layout of the lagoons establish the minimum requirements for the WMA 2excavation. The maximum extent is also physically constrained in some instances. For example,Rev. 1 40