Runit (Yvonne) Cleanup and Crater Containment 427 on schedule on [5 November 1977, and crater containment facilities were ready to begin operation on 15 May 1978.42 CRATER CONTAINMENT PROCEDURES Concepts for the POD crater containment design and procedures in CONPLAN I-76 for its execution were developed concurrently. According to the plans, a mole was to be constructed during the site preparation | phase (15 June 1977-15 April 1978) to minimize the effects of tides and storms and reduce the quantity of radiological particles which could escape to the ocean during containment operations. Later in this phase, when cleanup Operations began, contaminated soil and debris from the other islands would be stockpiled on Runit.43 Originally, all contaminated debris, including that from Runit, was to be collected before the tremie placement operations were complete in order to insure that it was properly encased in slurry.44 The POD design and the Field Command Operations Plan 600-77 (OPLAN) subsequently were amended to allow encasing contaminated debris during the soil-cement phase by forming a dike uround the debris and pumping contaminated slurry mix within the diked area.45-46 When sufficient soil was stockpiled to assure effective tremie placement of the slurry, containment operations would begin.47.48 Effective placement requires a stockpile large enough to permit as near a continuous flow of slurry as possible to provide as monolithic a mass as possible. Stockpiled material would be screened to the maximum size permitted by the concrete pump. Oversize material would be handled in the same manner as contaminated debris; i.e., encased in the slurry.?9 During tremie operations, construction would start on the northeast half of the keywall. By the time tremie operations were complete, most of the remaining contaminated soil should have been stockpiled so that the required volume and shape of the dome could be determined.59 The remaining keywall could then be constructed concurrent with soil-cement operations. The sequence and timing of these actions werecritical. They were plannedso as to permit the mosttimely and effective completion of the project. However, they had to be modified to compensate for unexpected events. MOLE CONSTRUCTION The POD design called for construction of a mole; i.e., a massive wall of large stones or dike (see Figure 8-9), around the ocean side of Cactus Crater prior to beginning containment operations in order to minimize the