and the specified removal criteria. Mr. McCraw read extracts from the four removal criteria contained in the operations plan (OPLAN 600-77) (Encl 6). Miss Barnes stated that it would be impossible to reach even the 50 percent confidence level of not having missed significant subsurface contamination without doing much more profile sampling. For example, to find a particular region of contamination two feet wide, under worst case with the seam parallel to the grid lines, would require sampling every four feet. To provide such characterization would require commitment of substantial resources. If the characterization is done on a simple yes-no criteria the sampling need not be so precise. Using the highest contamination level recorded on the island, 3200 pCi/g, Dr. Crites demonstrated a calculation showing that a pocket of contamination which would average greater than 400 pCi/g over a 21 meter (68.8 ft) field of view would be approximately seven meters in diameter, Thus sampling on a grid of less than seven meters should locate such a minimum pocket size subsurface contamination of interest. There was discussion of the one half distance technique for determining the presence or absence (yes~no) of subsurface contamination. Available data indicates only a few sample locations showing subsurface contamination at greater than 400 pCi/g levels. a 200 foot grid, Sample locations are spaced on approximately Moving one half the distance between greater than and less than sampie points iteratively should provide boundary definition of contamination areas of interest. This investigation would be limited to those areas where available data indicates high subsurface contamination levels, thus reducing the effort involved. of the iterative half distance. The "7 meter" criteria would set the lower bound