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Upper Stillwater Dam

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Owner: Central Utah Water Conservancy District
Designer: United States Bureau of Reclamation
Contractor: Tyger Construction Co. Inc. (Guy F. Atkinson Group)
Consultant to Designer: Dr M.R.H. Dunstan
Location: Duchesne, Duchesne County, Utah, USA
River: Rock Creek
Height: 91 m
Length: 815 m
Volume of RCC: 1 125 000 m³
Volume of dam: 1 281 000 m³
Reservoir capacity: 37M m³
Design flood: 2125 m³/sec
Start of Project: 01.12.1983
Start of RCC: 01.09.1985
Completion of RCC: 10.08.1987 (Two 7-month winter closedowns)
Completion of Project: 31.12.1987
Forming of upstream face: Horizontally-slipformed interlocking facing elements in a vertical face
Forming of downstream face: Horizontally-slipformed interlocking facing elements with slopes of 0.32 and 0.60:1 (H:V)
Forming of spillway: Horizontally-slipformed stepped interlocking facing elements with slopes of 0.32 and 0.60:1 (H:V)
Mixture proportions:
ASTM Type-I cement 79 kg/m³
ASTM Class F flyash 173 kg/m³
Water 98 kg/m³
Coarse aggregate 1325 kg/m³
Fine aggregate 680 kg/m³
Workability:
Loaded VeBe time 20 sec± (1987 season)

October 1985 - End of 1985 season showing RCC covered with insulation (click on image to enlarge)

June 1986 - Start of 1986 season from left abutment (click on image to enlarge)

June 1986 - Loading 35-tonne dump trucks from conveyor (click on image to enlarge)

June 1986 - Vibratory rollers and dozer at Upper Stillwater (click on image to enlarge)

June 1986 - Slipforming of an upstream facing element (click on image to enlarge)

June 1986 - Laser-guided off-set slipform paver slipforming an upstream facing element (click on image to enlarge)

June 1986 - Close-up of the finish on the inside of an upstream facing element (click on image to enlarge)

October 1986 - End of 1986 season (after a 128-day construction season) (click on image to enlarge)

June 1987 - Concrete plant showing very large flyash silo (click on image to enlarge)

June 1987 - RCC being spread using spreader-box on rear of truck (click on image to enlarge)

September 1987 - Construction of spillway crest block (click on image to enlarge)

September 1987 - Upper Stillwater dam nearing completion (click on image to enlarge)

September 1987 - Signboard with signatures of all involved with dam (click on image to enlarge)

August 2001 - Core from Upper Stillwater 14 years after completion (click on image to enlarge)

August 2001 - Close-up of 7-month joint without a bedding mix (click on image to enlarge)

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