only towards the lagoon, while unofficial eyewitness accounts mention that some soil was also moved toward the ocean. (The latter reports were supported by the fact that milligram-size particles of plutonium were found on both ocean and lagoon sides in 1972 and again during the cleanup.) There was also some indication in the reports that the contaminated soil was covered with plastic sheeting under the clean fill to warn that contamination was present. After the decontamination operation, the Fig event took place at the same GZ, further disturbing the soil and dispersing the contamination. As a result of Fig, Quince and the earlier events, the horizontal and vertical distribution of contamination, especially plutonium, was extremely heterogeneous in central Yvonne. All the GZ sites on Yvonne are shownin Figures 7-108 and 7-109. Other activities during test operations also contributed to the heterogeneity of the pattern of contamination on Yvonne. For example, soil was often levelled off or pushed into the ocean between nuclear tests, and fill was moved from one area to another during various construction operations. Numerous test stations, bunkers, concrete pads, and buildings were constructed on Yvonne; many still remained even after the cleanup. Most of the large quantity of debris on the island or the adjacent reef was north of the 1310 bunker, and some of it had exposure rates as high as 3mR/h at 1m in 1972. Asa result of the 24 events that directly affected Yvonne, the island received by far the highest accumulated H + 1 hour exposure rate in the Atoll, with 62,849 R/h. After the cessation of nuclear testing at Enewetak Atoll, Yvonne was sampled during the site selection process for the Pacific Cratering Experiments (PACE). (Details of the PACE program are in Sections 1.5 and 7.5.4.) Soil samples were taken in September 1971 near the Cactus, Lacrosse and Fig-Quince GZ's. Later, during the PACE operations, more samples were taken in one-foot increments to a depth of about ten feet during rotary drilling activities. Both sets of PACE-related samples were analyzed to obtain radiological data which were incorporated in cleanup decision-making. 1972 Survey Results The standard sampling procedures of the 1972 survey were modified for northern Yvonne because of the known heterogeneity of the radioactive contamination on the island. Instead of the usual random sampling design, soil samples were taken on a regular grid with approximately 200-foot spacing in the Fig-Quince area. Samples were also taken at 200-foot intervals along a line down the center of the island from the edge of the Fig-Quince area to the Cactus crater and south from there for about 200 m along the lagoon side. There were 45 locations in this group, and each was sampled in 10 em increments to a depth of 120 em. The situation on southern Yvonne was much less complex, so the standard procedures were used for the 51 locations sampled in the south half. One of these 51 was a 0-125 em profile, two were 0-165 em profiles, two were 0-185 em profiles, and the other 46 were 0-15 ecm cores. and animal samples were also taken on Yvonne. A number of plant The 1972 survey results verified the heterogeneity of the contamination on Yvonne, particularly in depth distributions. Also, several areas were shown to have high TRU activity. For example, there were several locations in the Fig-Quince area with 239,240py activity exceeding 100 pCi/g on the surface or at depths to 130 cm. Most of these locations were along the ocean and lagoon edges of the island. As might be expectedin light of the post-Quince decontamination operations, the depth distribution of activity was very erratic. Elevated 239,240 py activity was also found at several locations near the Cactus crater, but at only one was the activity in excess of 100 pCi/g. Near Cactus, the 239,240py activity tended to be homogeneous to about 60-80 em or to fall slowly with dep th; in several cases, the activity rose again below 80 cm. The depth distribution of 1°7Cs and 9%Sr was similar to the pattern for 239,240 py but less erratic. There wasalso less activity from these two isotopes, with the highest values in the Fig-Quince area being on the order of 10 pCi/g. Near the Cactus crater, the 137Cs and 9%Sr activities were higher, although most of the values were less than 50 pCi/g except for two locations with 99Sr activity greater than 100 pCi/g. Tables 7-1, 7-2 and 7-3 summarize the 1972 results for 137s, 90sp and 39,240py, respectively. 339