; 16 was laid first, and each panel was keyed to the abutting panels to prevent differential displacement (Pigure 6). Contaminated debris remaining after the “donut hole” was filled was placed into two. concrete “boxes” constructed for the purpose and attached to the landward side of the dome. The material within the Cactus Crater, covered by the concrete cap, consists of about 105,000 cubic yards of contaminated soil enclosing some 6,000 cubic yards of miscellaneous debris. The dome has a shallow slope and has been used as a landing pad for helicopters. The thick concrete key-wall around the dome is protected on the ocean side from wave action by a riprap “mole"*-—-a necessary precaution during the con- struction phase because during the three-year cleanup operation four major typhoons and tropical storms hit Enewetak Atoll causing extensive destruction. One typhoon required complete evacuation of the atoll. 3.10 References Atomic Energy Commission, Enewetak Radiological Survey, Report NVO-140, AEC-NV, « 3 vols., AEC, Washington, De Cee 1973. Report by AEC Task Group on Recommendations for Cleanup and Rehabilitation of Enewetak Atoll, AEC, Washington, D.C., 1974. Defense Nuclear Agency, Environmental Impact Statement-—Cleanup, Rehabilitation Resettlement of Enewetak Atoli—~Marshall Islands, 5 vols., DNA, Washington, D.C., 1975. - Pact Sheet--Enewetak Operation, DNA, Washington, DeCes 1980. eC _—— a tor es tae a) CF1 x3 - The Radiological Cleanup of Bnewetak Atoll, DNA, Washington, D.C., 1981 Ristvet, Byron L., Summaryof prilling Operations, DNA, Washington, D.C., 1980.