10 These standards subsequently were modified by the Department of Energy (DOE) to inelude all the transuranics, not just plutonium. The land-use cleanup standards also were revised to permit not more than 40 peci/g for residential islands, 80 pCi/g for agricultural islands, _and 160 pci/g for food-gathering islands. 3.3 Disposal Options * ' During the planning stages a major consideration was the method of disposal for any plutonium-contaminated material. Several options were initially considered "including returning it to the United States, casting it into concrete blocks, dumping it into a crater with a concrete cap, or dumping it in the ecean or lagoon” (Defense Nuclear Agency 1981, p. 94). Although strong arguments were made for lagoon Or ocean dumping, the Environmental Protection Agency (EPA) believed that national policy prohibited such disposal. This view prevailed over that of the Energy Research and Development Administration (ZRDA) and the final environmental impact statement (April 1975) identified Crater entombment as the selected disposal method. Disposal criteria were reviewed again in August 1977 by the so-called Bair Committee. This group advocated ocean dumping as the preferred solution with lagoon dumping as an acceptable alternative but recognized that any change would require the EIS to be reopened andthat EPA opposition to those alternatives would still remain. ‘The Bair Committee’s final view was that “terrestial disposal on Runit Island with a concrete cover" was the best practical alternative (letter from W. Jd. Bair, et al. to J. L. Liverman, Assistant Administrator for Environment and Safety, ERDA, August 17, 1977). Thus, the cleanup plan finally adopted called for radiologically contaminated soil and debris present on many islands in the atoll to be collected and transported to Runit and contained in a soil-cement matrix in Cactus Crater, surrounded by a concrete keywall, and covered by a concrete cap. . 3.4 Radioactive Contaminants © The radionuclides of principal concern at Enewetak are the transuranics, mainly plutonium-239, and the fission products, strontium-90 and cesium=-137. The transuranics are relatively insoluble and therefore have remained very near the surface. The strontium and cesiun, however, are more soluble and have leached to.a considerable depth. Indeed, the DNA (1980) stated: . The AEC's radiological survey had disclosed that, except on the island of Runit, most high transuranic concentrations were in the top few centimetres of soil. This was not the case with suburanics which, because of their water solubility, were distributed to considerable depth. ... ‘Exeision of soil con- taminated with suburanics (fission products], however, was simply not practicable. To do so would require such extensive soil removal as to render the island useless for habitation or subsistence agriculture. Thus, the subsequent cleanup concentrated on the problem of transuranics. 90048528