se: erations soil Cleanup Op walls, resulting in cave-ins.. The clamshell proved to be more undercut the lifting soil and allowing water to drain back into the hole, successfulgin izin the spread of contamination. Thetest revealed the need for a minim! | enclosure as there was a 33 percent increase in the width and Lone the hole through cave-ins over a 24-hour period. Additional lengt sations on 15 August and 29 September 1978 confirmed the results investier tests; i.e., a constant water level 2 feet below the surface and Ot table excavation walls which fell in on 1:3 to 1:10 slopes, depending on watet movement.” ; ; During the initial planning, Field Command requested that Pacific Ocean Division (POD) of the Corps of Engineers submit designs for excavations, including both open and sheetpile procedures. 41 A design report was submitted on 15 September 197842 and, in a letter dated 6 October 1978, POD recommended that the JTG proceed to excavate contaminated material without the use of sheetpiling. The proposed scheme provided for a series of systematic overlapping trench excavations since POD suspected that the contaminated material was no more than 6 feet deep within the boundariesof the old tidal pond. POD also believed chat, even if it were required to go as deep as 18 to 20 feet, the excavation could be accomplished with available equipment operated by skilled personnel. . A meeting was to be held at POD offices in Honolulu on 6, November 1978 to make a final recommendation to DNA on procedures to be used for removal of contaminated soil and debris from the Aomonburialsite. The essential decision to be made was whether to select the PODrecommendedprocedureorto place sheet pile aroundall four sides of the crypt. Also to be considered wasthe alternative to place sheetpiling around three sides, with the end walls extended to the causeway prior to excavation.43 AOMON CRYPT CONFERENCE: 8 NOVEMBER 1978 This meeting took place on 8 November 1978, attended by representatives of POD, JTG, H&N-PTD, DOE-Pacific Area Support Office, DOE-NV, DOE-Germantown, F&S, U.S. Army Support CommandHawaii, Field Command, and Headquarters DNA.*4 Based on decisionsat this meeting, the CJTG was given the following guidance:45 a. Start a drilling and core sampling program to determine vertical and lateral extent of radioactive contamination within the crypt. b. After completion ofinitial core sampling, begin excavating without containment about | December 1978 in accordance with operational concepts developed during the meeting.