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Fig. 5 Fig. 5 Plan view of 2017 and 2018 repair/replacement alternative measures for the FCO Spillway chute Table 1 2017 and 2018 Repair/Replacement Measures for the FCO Spillway chute FCO Spillway Chute Reach Stationing (feet) Length (feet) Length (meters) 2017 Construction 2018 Construction Upper Chute 13+00 – 20+30 730 222 Minor repairs Replacement 20+30 – 28+20 790 241 Replacement - Lower Chute 28+20 – 39+30 1110 338 RCC Backfill Structural concrete 39+30 – 43+00 370 113 Replacement - Total 13+00 – 43+00 3000 914 Replacement 2.4.2. Emergency Spillway Alternatives The Emergency Spillway is an ungated monolith/weir structure that is approximately 527 m (1730 ft) wide at the weir crest. The left 283 m (930 ft) portion consists of concrete-gravity ogee monoliths/weir sections that were keyed into slightly-weathered rock. The structural heights of the monoliths range as high as 27 m (90 ft). The right 244 m (800 ft) portion is a cut section with a small 30 cm (1-ft) high concrete ogee weir. During the Oroville Spillway Incident, there was great concern that rapidly developing head-cutting erosion under a relatively 22.5 m Replaced by Nov. 1, 2018 240.8 m Replaced by Nov. 1, 2017 338 m RCC Chute by Nov. 1, 2017 112.8 m Replaced by Nov ‘17 UPPER CHUTE LOWER CHUTE 72