ACTIVITY LEVELS IN SOIL STOCKPILE ON YVONNE NEAR SOUTHERN LIP OF CACTUS CRATER DATED: 25 May 1979 DOE/ERSP TECH NOTE NO.15.0 AUTHORS: D. H. Denham, PNL N. R. Johnson, EIC Introduction and Sampling In preparation for the Tremie operation for crater disposal of contaminated soil and debris on the north end of Yvonne, part of the original Cactus Crater lip was dozed away from the crater. Although there was concern that the crater lip may have significant subsurface contamination, portable instrument surveys and soil sampling by the FRST (fall 1977) apparently did not confirm that suspicion. Following completion of the Tremie operation, another section of the original crater lip was dozed away from the crater toward the south in early May 1979. That action left a readily accessible lip face (see Figure B-15-]) 3-4 m high and of similar width. Ten sidewall samples of this face were taken by Dick Powell (EIC) and John Gallimore (DOE Tech Advisor) on 11 May 1979. During the ensuing week further portions of the crater lip were dozed away from the old lip area to provide space for completing the circular concrete keywall. All of this lip material was pushed into a 2000 m3* soil stockpile (see Figure B-15-1) bounded approximately by excess keywall sections, debris hauling roads, and the remaining crater lip. pipes. 7 This action uncovered several line-of-sight (LOS) At the request of LTC Al Erickson, J-3, JTG, we launched a second soil sampling mission to Yvonne on 17 May 1979 The purpgse of this latter mission was to characterize the radioactivity, primarily TRU, within this 2000 m*° stockpile near the southern lip of Cactus Crater. A sketch of the stockpile showing the approximate locations of samples is shown in Figure B-15-2. Surface soil samples were collected in petri dishes from 10 locations (what would have been location No. 6 was missed) on top of the pile and 7 locations on the 7-meter high southern face. Subsurface samples were Collected at surface locations 5 and 8 near the center of the pile. These samples (numbers 12 to 16 at 5 and 17 to 19 at 8) were taken at 20 em intervals to a maximum depth of 1 m. Six subsurface samples (numbers 29 to 34) were taken at about 60 em depth (perpendicular to the sloping face) along the western and eastern sides of the 7-meter high southern face. Results and Conclusions Based on our physical measurements of the stockpile, we estimated the volume to be a few percent above that estimated by JTG. A total of 41 soil samples were collected as part of these characterizations. The 10 initial samples taken on 11 May are assumed to represent the "bottom" of the stockpile since they were collected prior to the time that portion of the crater lip was dozed away. Results of the other 31 samples provide an indication of the surface and limited subsurface activity levels in the pile. the EG&G IMP at Ursula. All samples were collected in petri dishes and were gamma scanned by The results are presented below. Note: These values are based on a nominal weight of 130 g per sample since the individual samples were not weighed. This should not result in greater than a 30% error in the estimated values. Estimated Radionuclide Concentrations (pCi/g) 241Am 137Cs 60Co Average 1.3 29 7.3 Range 0 - 3.5 12 - 54 1.8 - 16 *Volume furnished by JTG **The original Tech Note included a 5-frame photo composite that was reproduction here. Figure references have been changed to reflect the deletion. B-15-1 not suitable for