Le 360 RADIOLOGICAL CLEANUP OF ENEWETAK ATOLL contaminated soil and metal and encountered a high water table Which hampered digging below 6 feet.35.56 Results were discussed by Fielg Command and JTG engineers during a conference in Albuquerque in February 1978. Most agreed that use of a steel sheetpiling enclosure normal excavation techniques, and a drain pile should permit remova} of the material without spreading contamination. Others felt that more data were required. The secondinvestigation was conducted in April 1978, using backhoes and hand augers. Red and green dye was poured into someof the holesin an attempt to trace the flow of tidal water. Results of this test were inconclusive and somewhat confusing. In some holes, the dye appeared tg intensify in color rather than fade asit diluted in the ground water.37.38 At the 4 May 1978 conference, the Director, DNA decided that a major effort would be made to excavate the crypt. On 13 May 1978, the USAE submitted a preliminary design schemefor the excavation. This plan calleq for a 50-foot by 280-foot sheet pile enclosure, from which 12,000 cubic yards of contaminated material would be excavated. Test wells, borings, and backhoe samples had indicated that the water level was 2 feet below the surface, and unstablesoil existed around the excavations.2? At the same conference, DOE-ERSP had indicated that they would identify experienced contractors to look at various solutions for cleaning out the Aomon Crypt. At a meeting of DOE and Field Command representatives at DOE-NV on 6 June 1978, a representative of Fenix and Scission, Inc. (F&S) presented a concept for removing the contaminated soil in the crypt. The proposed concept provided for a hydraulic dredging operation, using a specially fabricated jet dredge head. Under the F&S proposal, the size of material removed by dredging would be limited to the screen mesh size of 2-3/4 inches. Special equipmentrequiring long delivery times and technical assistance would be needed.Settling tanks would be required for separating water and soil so that emptying the tanks would require additional equipment and add to the complexity. In short, the method appeared to be expensive in money, time, and complexity and had no particular advantage over more conventional methods. Therefore, it was not adopted. At the June 1978 meeting, a recommendation was madetostart a test excavation using a crane with dragline to characterize the contents of the crypt and the stability of the soil. It was proposed to start the test excavation while the investigation of the jet dredge concept was underway. Another moredetailed exploratory excavation was conducted on 26 July 1978. During this exploration, a 6-foot deep hole with the approximate dimensions of 10 feet by 12 feet was dug using both a hydraulically operated backhoeand a crane with clamshell. The water which rushed into the hole confirmed a constant water level 2 feet below the surface. It also |