and dead branches were encountered in these turning areas. This material so fouled the plow and interfered with its ability to turn the soil that it was necessary to stop frequently and clear the plow by hand. A bulldozer was used to blade off this area and work then proceeded much more smoothly. The bulldozer operator experienced some initial difficulty in properly overlapping the furrows and in aligning the cuts to the track. By the second day, however, this was well worked out and plowing progressed much better. Occasionally old cable was turned up. This would hang in the plow and eventually required clearing. Clearing the plow of debris required lifting it out of the ground with a front-end loader and was done outside of the measurement plots in each case. Actual plowing time for the two sections (1/4 hectare) was 1-1/2 hours. The plow was pulled to its full depth (about 50 em) at a rate of approximately 67 m/min. This was accomplished without difficulty despite occasional uprooting of large pieces of coral. Turning at each end slowed progress somewhat. 3. Ground Preparation Post-Plowing Plowing left the ground very rough. The hills and valleys of the furrows were such as to. preclude moving the IMP in for measurements and would have made profile soil sampling questionable (the surface varied by up to 20 em). To facilitate measurements, the plowed areas were backbladed with a bulldozer and then tracked over several times to smooth and compact the surface. A couple of rains followed before measurements could be initiated, leaving a firm soil which was easily sampled. As drying occurred, the surface became quite dusty. Resuits 1. IMP Survey An IMP survey of the plowed blocks showed considerable reduction in surface contamination. Re-survey of the "control" (unplowed) blocks on the same date showed no significant change from earlier measurements. Figure B-9-10 shows the numerical results of the IMP estimate of total transuranies (TRU), based on 24l1Am measurements, both before and after plowing. Further discussion of these results is given in the "Statistical Analysis" below. 62.3 2 1 Oo 48.8 oO 109 91.6 ° o 4-— Before 66.3 12.0 107 4.3 —-— After 67.4 98.1 69.9 64.8 \¢— Before o oO oO o 63.9 12.3 63.5 4.3 13 14 15 16 4—After oo NORTH ——__—_—_ Figure B-9-10. Comparison of IMP TRU Surface Concentrations Before and After Plowing, pCi/g B-9-18