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7. An assessment of the construction schedule showed that using RCC for foundation replacement would be a feasible solution for reconstruction of a usable FCO Spillway chute by November 1, 2017. 8. Should early storms arise in the fall of 2017, requiring the operation of the FCO Spillway chute before the scheduled completion on November 1st, the RCC should be resistant to scour up to moderate flows – about 1400 m3/s (50,000 ft3/s) or higher under temporary conditions. 9. The completed spillway modification project using RCC would have a positive appearance of a robust and complete solution that restores public confidence in the reliable operation of Oroville Dam. 10. The completed FCO Spillway chute, using RCC, would be a permanent solution capable of a design life of 100 years or more, capable of passing large flows up to the original design value of about 8400 m3/s (296,000 ft3/s) Based on these initial benefits, the FCO recovery solution, using RCC foundation replacement in the scoured areas, was selected for preliminary design early in the evaluation process. With selection of RCC for the FCO Spillway chute, this decision led to the consideration of RCC for other aspects of the recovery design, including the Emergency Spillway buttress and spillway apron. 5. RCC PRELIMINARY DESIGN SOLUTION The use of RCC for the FCO Spillway chute reconstruction was initially proposed as shown in Fig. 4, which included a conventional reinforced-concrete slab overlay as well as reinforced-concrete chute walls against RCC. In this initial concept, RCC was envisioned as the primary structural feature for the 6.1 meter (20 foot) high FCO Spillway chute walls with 0.76 meter (2.5 foot) thick reinforced-concrete vertical inside walls that were tied-back into the RCC. Fig. 4 Preliminary RCC Concept The constructability of the initial concept envisioned that the RCC chute and walls would be constructed first, then the reinforced-concrete slabs and walls would be placed in sequence later within the same construction season. This concept, developed at the 30-percent design completion, was the basis for the original construction bid. 92