Conceptual Site Model - Argonne National Laboratory

WVDP Phase 1 CSAPWMA 4, this is most likely to occur in the northern and northwestern portion of theWMA.For every area where standing water or saturated soil conditions prevent GWS datacollection, systematic soil sampling will take place. For wetland areas less than 200 m 2 insize, one sample will be collected. For areas between 200 and 1,000 m 2 in size, onesample per 200 m 2 will be collected. For areas between 1,000 and 2,500 m 2 in size, fivesamples will be collected. For areas exceeding 2,500 m 2 in size, at minimum one samplewill be collected per 500-m 2 area. One sample will be collected from each locationrepresentative of a 0–15 cm depth interval. In the case where an area has more than onelocation, locations will be selected so that each representative area does not overlap andprovides systematic coverage of the area of interest. [contingent]• Hot Spots. If GWS data indicate the presence of contamination that possibly exceeds“hot spot” (CG emc ) standards or an isolated elevated area is identified that appearsindicative of a discrete release, the location of concern will be sampled with a biasedsample. If biased samples are collected from a particular location, they will be collectedfrom two depth intervals: 0-15 cm, and 15 cm-1 m. The 0–15 cm samples will beanalyzed for the 12 radionuclides of potential interest in addition to the 18 ROI. Onedown-hole gamma scan will be conducted from each biased location. The purpose ofthese samples is to resolve GWS anomalies, evaluate the appropriateness of the currentROI list, and verify the absence of additional ROI. [contingent]• CG w Sampling. Surface soil sampling may be conducted after the GWS to further clarifyresults, with the level and nature of sampling dependent on GWS results.oIf GWS results indicate contamination impacts above background levels but thatsurface soil contaminant levels exceeding surface soil CG w requirements areunlikely, the area of interest will be systematically sampled using a triangulargrid with a density of one sample per 400 m 2 . One sample will be collected fromeach location representative of a 0–15 cm depth interval. Locations will beselected to provide systematic coverage of the areas. The purpose is to documentthe activity concentrations present in surface soils within WMA 4. [contingent]Rev. 1 D-9