1. 2. Top 1 cm of soil: Based on compositing 15 subsamples obtained Top 5 cm of soil: Based on compositing five subsamples obtained using a 5- by 6-cm template (450 em?) . using a 10- by 10-cm scoop (500 cm). A limited number of 5- to 10-cm depth profile samples and individual subsamples of the 1- and 5—cm samples were also obtained and analyzed. All samples were analyzed for plutonium-239. A selected number of samples were analyzed for cesium-137 to evaluate allegations that the Rocky Flats plant was the source of localized cesium-137 contamination (Johnson, 1977). Eight duplicate analyses were evaluated to assess the uncertainty of the sample aliquoting and analysis technique for plutonium-239, Statistical testing and plotting of the data indicated that the variances were not independent of the means. Therefore, the coefficient of variation (C) was used, versus the variances, for testing the variations of results for the different data sets. There were only a small number of results (generally five) in the various data groups. Thus, it is emphasized that limited significance should be placed on the test results. In general, equality was not rejected for any of the data groups; however, because of the limited amount of data, the test results give only a weak confirmation that statistical differences are not present. Although there is some uncertainty in both the direction and magnitude of indicated trends, the trends are believed to be the best observations based on the available data. The C for five 0- to l-cm samples collected from a 2- by 2-m plot was about one-half of that for the whole 12- by 14-m site. This trend indicates that the deposition of plutonium for the total site was more variable than that in the 2- by 2-m plot. The C's for the activity per unit area results for the O- to l-cm technique are similar to but somewhat larger than for the O- to 5-cm tech- nique. The range of the C's for the l-cm technique (mean of 42 percent, range of 18 to 69) overlap the C's for the 0~ to 5-cm technique (mean 30 percent, range of 19 to 47). The C's for the amount of sampled mass (less than 10-mesh) per unit area reflect smaller differences between the techniques than the activity per unit area C's. This indicates a significant fraction of the differences of the variabilities of the techniques may be due to variations in the deposition of plutonium. There was considerable difficulty in applying the EPA O- to 5-cm technique for the compact rocky soils around Rocky Flats. It is possible that other techniques for sampling down to 5 cm or deeper, more adaptable to the Rocky Flats type of environment, might exhibit less variability 667