in separate letters to Paul Dunaway (NAEG) by R. 0. Gilbert and E. B. Fowler in December of 1975, and there were undoubtedly other NAEG scientists considering various aspects of possible future cleanup activities. Future Studies During 1977, we prepared a protocol to take additional FIDLER, soil, and vegetation samples at the Clean Slate 2 site on TTR in anticipation of a possible remedial action or cleanup effort at that site. Aerial surveys by EG&G, Las Vegas, in February, 1977, indicated some additional sampling to refine estimates of Am surface contamination at this site. The field sampling design completed in October, 1977, is given in Figure 7. This design is an outgrowth of a preliminary plan sent to the NAEG in April, 1977. The sampling objectives are (i) to refine estimates of spatial patterns and inventory of Pu and Am, (ii) to evaluate whether a cattle grazing study might be conducted, and (iii) to collect information suitable to better define the area that might require remedial or cleanup action according to recently proposed EPA guidelines.* Soil samples to 1-, 2.5-, and 5-cm depths would be collected using 5-inch-~diameter rings in the configuration shown in Figure 8. Surface FIDLER readings would be taken over each sampling ring and at 1-foot height over the cluster of three. The l-cm samples would be sieved to 2-mm size and both frac-— tions analyzed. The l-cm samples on 2-mm size fractions are included since the proposed EPA guidelines call for this type of sample. At 23 grid locations, both 10- and 50-gram aliquots of soil would be analyzed for Pu (wet chemistry) and Am (Ge(Li) or wet chemistry). The 50-gram aliquots are included to help evaluate the variability of these larger aliquots relative to the standard 10-g NAEG aliquot size used up to the present time. This is motivated by results of the special aliquot size study discussed by Doctor and Gilbert (1978) that indicates substantial reduction in variability between aliquots from the same sample if 50-gram rather than 1- or 10-gram aliquots are used. There are a number of other sampling questions that need to be studied in anticipation of possible cleanup efforts. There is a need, e.g., to determine under what conditions and levels of contamination FIDLER field data could be used in such studies. A great many FIDLER readings taken at a height of 1 foot were obtained at safety-shot sites (Gilbert and Eberhardt, 1974, and Gilbert et al., 1975) that could be examined in greater detail. Information on FIDLER readings taken at the soil surface as well as at 1-foot height were taken as part of the "variability with distance” study conducted in Area 13 (see Doctor and Gilbert, 1978). More information of this type will be generated in the Clean Slate 2 *Proposed Guidance on Dose Limits for Persons Exposed to Transuranium Elements in the General Environment,'’ FEDERAL REGISTER NOTICE, November 1977, U.S. Environmental Protection Agency, Office of Radiation Programs, Washington, D.C. 20460. 470