FIGURE 6-27, CACTUS DOME ON ISLAND YVONNE. At project completion, a concrete-capped dome 25 feet high and 370 feet in diameter exists where a 30-foot deep crater used to be. (April 1980) On 27 May 1979, a working conference was held by JTG to determine a plan to achieve the maximum effectiveness in a limited cleanup effort within the Fig/Quince area. Data available at the time indicated that up to 6,000 yd° of soil could be placed in the Cactus Dome (Figure 6-26) following completion of soil removal from other islands, but a conservative decision was made to save space for 4,000 yd3, "just in case", until all other soil removal was actually completed. A detailed plan was devised to remove soil, 20 em at a lift, from one-sixteenth-hectare squares, with the square indicated to have the highest TRU activity being lifted first. After each lift, the IMP would return to do a new gamma sean. The process would be repeated until 2,000 yas had been removed to the soil/eement operation at the Caetus Crater/Dome. (A 20-em lift from one-sixteenth hectare produced about 160 yas of soil, so 12 squares could be treated. Some squares were lifted once, others as often as five times because of the "highest first" concept. In essence, subsurface excision was being done based on "surface" measurements rather than subsurface profiling.) 197