Topping Old Soil with New Soil. This alternative involves the dredging for a source of replacement soil or importation of suitable soil to Bikini and its placement over existing contaminated soils to a sufficient thickness to preclude plant uptake of unstable cesium from the lower contaminated layers. This alternative would also require removal, grubbing, and destruction of existing vegetation. Although this alternative would preciude the need for soil excavation, it would still require large quantities of topping soils, either from dredging sites at Bikini or from off-atoll sources of soil. Also, groundwater on Bikini Island would continue to be contaminated beyond drinking water standards for many years. Ocean Disposal. Disposal of excavated soil into open ocean waters is technically feasible and could be accomplished at a site away from the atoll to eliminate sedimentation impact to Bikini's coral reef ecosystems. However, there may be institutional or legal constraints against this approach, and the proposal would be extremely controversial, particularly within the international community. Ocean disposal also may not be a politically feasible or acceptable alternative. Qpen Lagoon Disposal. Disposal of excavated soil in open lagoon waters can lead to the risk of sediment or turbidity damage to lagoon reefs or fisheries within or downcurrent of the disposal areas. A more feasible approach would be lagoon disposal in one or more of several large craters created during nuclear weapons testing between 1946-1958, including BRAVO crater. Crater disposal has the advantage of confining turbidity and sedimentation to environments chronically disturbed by previous weapons testing. Thus open lagoon disposal appears less desirable from an environmental perspective. Since other lagoon alternatives (crater disposal) are more feasible and desirable, it may be pointless to pursue open lagoon disposal much further. Causeway Construction. The Bikinians have expressed support for a causeway alternative, most recently in September 1984. Use of excavated material for the construction of a 8 km long road causeway over the reef between Eneu and Bikini Islands was earlier proposed as one "disposal" alternative that could also improve transportation and communication Jinks between the two large inhabitable islands of the atoll. However, this option would cost roughly $40 million more than the cost of the next most expensive disposal alternatives. In addition, the causeway and its construction would be expected to destroy reef and subsistence fishery habitats, disrupt water circulation on either side of the causeway, reduce the migratory routes for reef biota, cause major changes to the water circulation of the eastern Tagoon, and-perhaps render lagoon circulation more sluggish as a whole. In addition the causeway would be vulnerable to damage from storm waves and would require a program of regular maintenance. There are likely cheaper alternatives for improving transportation and communication links between Eneu and Bikini Island including the construction of protected harbor basins on the lagoon side of both islands, from which shuttle boats could operate. The harbors would also provide additional benefits for improved cargo handling and commerce, fishery development, emergency evacuation of the atoll by ship, etc. Detailed discussion of harbor and other transportation needs, however, are beyond the scope of the committee's present work. S008 4 E-1]