—~
Runit (Yvonne) Cleanup and Crater Containment
the design was selected to begin the keywall; i.e., a radius of approximat
an arc v
185 feet from the center of the crater. Using the 185-foot radius,
surveyed and staked out on the reef. The arc fell about 12 feet outsidet
t
crater lip. Excavation to place keywall forms began on the reef
following week,’? and thefirst 10-foot section of keywall was placed t
week of 6 November 1978.78 A field engineering decision was made
|
change the form length to 12 feet to accommodate use of standard s
plywood. This resulted in fewer forms being required for the northern h
(48 in lieu of 58) without detracting from the roundnessof the keywall.”
Keywall construction was hampered by reef and tide conditio:
Excavation and forming could be accomplished only during that half o
day when the tide was out. The excavations were full of water even at |c
tide, causing difficult and unpleasant working conditions and hamperi
excavation (Figure 8-26). Tidal water in trenches also hampered ¢t
proper placement of concrete (Figure 8-27). Dumping concreteinto t
water-filled forms resulted in laitance in some sections, as was revealed
subsequent core samples. 80
Concrete for the keywall was mixed using a type 16S concrete mixer ur
tremie operations were completed. Thereafter, the batch plant, which v
decontaminated on 27 February 1979, was used to produce clean concre
which was then transported to the keywail construction site by transit-n
trucks.
‘.
~
Cr,
Ns
e
3
.
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FIGURE 8-26. BUILDING THE KEYWALL.