It was pointed out in Gilbert et al. (1975, Fig. 28) that the contour lines obtained to date for Area 13 and GMX are biased, it is believed, due in part, to the nearest-neighbor estimatiom method and to the use of soil samples collected at random locations within strata (stratified random sampling) resulting in inadequate coverage of portions of the field. One approach that may reduce the bias in these contours is to fit contours to the log-transformed data. This might be effective since the large concentration peaks would be scaled down, it is presumed, less variable data. for making more accurate fits to the This bias might also be reduced by the use of more strata or the division of strata into substrata within which samples would still be taken at random. This approach would tend to reduce the size of areas where no samples were collected, and hence reduce the bias due to such gaps in information. Another approach would be to increase the number of locations at which samples are taken. This could be done as part of a "double sampling'' scheme for estimating plutonium inventory in soil so that costs would not be expected to be greater than for presently used sampling designs. The general idea, as it might be applied to a safety-shot site, would be to define strata using the FIDLER and to collect a relatively large number of soil samples within strata. All 241 samples would be analyzed for Am using the Ge(Li) system and a small proportion would also be analyzed for 239-240Pu using wet chemistry techniques (both Pu and Am analyses being done on the same aliquot from the soil sample). known as double sampling. This kind of sampling procedure is Gilbert and Eberhardt (1975) evaluated its effectiveness for Area 13 and GMX and concluded that except for the two lowest plutonium concentration strata, the technique can yield estimates of plutonium inventory with greater precision than possible with plutonium analyses alone for a fixed cost. This result has implications relative to the estimation of unbiased concentration contours since Gilbert and Eberhardt (1975) estimated that about twice as many soil samples would need to be collected using double sampling than were used to estimate Pu inventory using stratified random sampling. All of these soil samples would be Ge(Li) scanned for 241am, but less than 20% would also need to be analyzed for 2392405p, (keeping total cost equal to that in estimating inventory using 104