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UNITED STATES

DEPARTMENT OF THE INTERIOR

Douglas McKay, Secretary

//. i BUREAU OF RECLAMATION

Wilbur A. Dexheimer, Commissioner
L. N. McClellan, Assistant Commissioner and Chief Engineer

TECHNICAL RECORD

OF

DESIGN AND CONSTRUCTION

O'SULLIVAN DAM

Constructed 1947-1949

Columbia Basin Project

Denver, Colorado
1954

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General Information

Purpose: Irrigation and catchment basin for return flow and waste water from irri-
gated lands in drainage area.
Location: On lower Crab Creek, about 22 miles south and 12 miles east of Ephrata,

Wash.
Constructed: 1947-1949

Water supply: Lower Crab Creek - at certain times of year fed completely by re-
turn flow and waste water from irrigated lands in drainage area.
Drainage area: 4, 000 square miles
Maximum flood: 3, 000 cubic feet per second (1943)
Reservoir:

Area: 32, 000 acres

Total storage: 675,000 acre-feet at elevation 1052.0 (spillway crest)

Irrigation storage: 569, 000 acre-feet above Potholes East canal

headworks gate sill (EL. 1008.0)
Maximum water surface: El. 1055.0
Minimum water surface: El. 940.0

Dam

Type: Zoned rolled-earth fill

Foundation: Basalt, varying from dense to crushed and sheared types

Slope protection: Layer of rock on upstream and downstream slopes

Dimensions:

Height: 160 feet above streambed, 225 feet above excavation at deepest point
Crest length: 19, 000 feet
Crest elevation: 1061.0
Volume: 8, 770, 000 cubic yards

Slopes: Upstream, 4 to 1 to elevation 960, 3 to 1 to elevation 1047. 5, then
2-1/2 to 1 to elevation 1061

Downstream, 2 to 1 to elevation 930, 4 to 1 to elevation 960, then 2 to 1 to elevation 1061 Cutoff trench: 15-foot bottom width from elevation 1060 to elevation 1045; from elevation 1045 to elevation 1010 the trench was widened 1 foot for each foot the bottom of the trench was below elevation 1045 and from elevation 1010 down the width remained 50 feet; side slopes of trench 1-1/2 to 1

Spillway and Outlet Works

Type of spillway: Overflow open channel, concrete crest width, 500 feet

Spillway crest: Elevation 1052. 0

Maximum discharge: Spillway, 7,500 cubic feet per second at maximum water

surface

Outlets: 4- by 4-foot gate, 1, 150 cubic feet per second; 18inch gate, 67 cubic feet per second

Outlet conduit: 7 feet 6 inches in diameter, 725 feet long

Outlet works stilling basin: unlined - excavated in rock

Concrete: 2, 085 cubic yards

Reinforcement steel: 97, 775 pounds

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