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85

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..........do.....

8.00

Construction of remote-control

house (see also E. W. O. no.
23 at p. 137 and no. 26 at p.
137; also 0. C. no. 13 at p.

140).
86 Concrete: Parapet wall on

Cu. yd...
crest of dam (see C.O. no.
7 at p. 10; also footnote 4,
and contract 12r-2865 Cox

& Christiansen at p. 144).
87 Concrete: Cradles for 72-inch 25. 5 ...do...

outlet pipes.
88 Rubble concrete paving down-

stream from spillway and
outlet basin (see also footnote

3, and 0. C. no. 1b at p. 144.)
Cutting, bending, and placing (357, 454) Lb......

reinforcing steel (memoran-
dum-cost included in con-

crete items in which placed).
90 | Installing and painting radial 128, 074 ...do.....

gates and operating mechan-
ism (see also E. W. O. no. 14
at p. 136, and E. W. O. no.

21 at p. 137).
Installing and painting 5. by 185, 971 ...do...

[blocks in formation]

.02

3, 719

6-foot high-pressure emer-
gency gates and operating
mechanism (see also E. W.O.

no. 24 at p. 137). 1 Job.

. 118

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94

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92 Installing and painting high

pressure control piping and

oil tanks for emergency gates. 93 | Installing and painting 72

inch outlet pipes (see also

E. W. O. no. 12 at p. 136). Installing and painting 60.

inch balanced needle valves and control mechanism (see also E. W. O. no. 19 at p. 136, and E. W. O. no. 27 at p. 137; also O. C. no. 5a at p. 139, and O. C. no. 14

at p. 140). 95 | Installing and painting metal

stairs and floor system in

needle valve structure. 96 | Installing and painting gantry

crane and rail. Installing and painting metal

work in trashrack structure (see also E. W. O. no. 10 at

p. 135). 98 Installing and painting spiral

stairs (see also E. W. 0.

no. 16 at p. 136). Installing and painting pipe

handrailing. 100 Installing and painting metal

lampposts. 101 Installing electrical conduits,

fittings and boxes, sizes 1

inch and under. 102 Installing electrical conduits,

fittings and boxes, sizes 1%;

112 inches. 103 | Installing electrical conduc

tors, fittings, and apparatus,

complete. 104 Erecting timber in walk along

72-inch outlet pipe, and stairway to emergency gate

structure. 105 Constructing and painting

wood guardrail. 106 | Constructing and painting

standard highway fence.

Subtotal, contract items Extra work orders...... Orders for changes...... Claims................

Total cost........

99

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2 83% percent.

BIBLIOGRAPHY

Echo Dam-An Earth and Rock Fill Dam on the Weber

River. Reclamation Era, September 1928. Echo Dam, Progress of Construction. Western Construc

tion News, Dec. 10, 1929.

Design and Construction of Two New Reclamation Dams.

Engineering News-Record, June 18, 1931. Construction of the Echo Dam. Reclamation Era,

October 1931.

MCKAY DAM

UMATILLA PROJECT, OREGON

BY M. E. TRENAM, ASSISTANT ENGINEER, BUREAU OF RECLAMATION

forced into each hole, until refusal, at a maximum pressure of 100 pounds per square inch.

THE DAM

MCKAY DAM is located about 7 miles south of Pendleton, Oreg., on McKay Creek, approximately 5 miles above its confluence with Umatilla River. The reservoir created by the dam is about 4 miles long and 1 mile wide, with a storage capacity of 73,000 acre-feet at the maximum surface elevation, 1,322 feet above sea level. Stored water is used to supplement the natural flow of Umatilla River for irrigation of about 38,000 acres of developed lands in the vicinity of Echo, Stanfield, and Hermiston, Oreg. The principal features involved in the construction of the dam consisted of the gravel embankment, protected by a continuous, reinforced concrete slab on the upstream slope; a concrete-lined, outlet tunnel driven through the rock of the right abutment; and an open-cut, side-channel spillway located on the right abutment.

FOUNDATION

The foundation material consisted of exposed lava rock on the right abutment, lava rock overlain with soil and gravel to a depth of from 1 to 12 feet across the valley floor, and lava rock overlain with soil and cemented gravel on the left abutment. The depth of overburden on the left abutment varied from a few feet at the valley floor to an undetermined depth at the top of the dam.

All topsoil on the area occupied by the dam was stripped down to compact gravel, cemented gravel, or solid rock, and deposited above the upstream toe of the dam, where it was later spread to form an earth blanket over the upstream cut-off wall.

Foundation drainage was provided by constructing a rockfill embankment, to form the downstream toe of the dam, and by placing a loose-rock blanket, 12 inches thick, over the downstream third of the foundation wherever solid rock was exposed.

Trenches for the cut-off walls were excavated to solid rock or to impervious cemented gravel. Holes for pressure grouting were drilled in the botton of the trenches. The holes were spaced at from 272- to 10-foot centers, spacings under 10 feet being determined by progressively grouting the holes as drilled. The holes varied uniformly in depth from 45 feet at the maximum section of the dam to a minimum of 20 feet at the abutments. Cement grout was

The embankment has a crest length of 2,700 feet, a maximum height of 165 feet, and contains 2,287,000 cubic yards of material. The downstream slope is 2 to 1, and the upstream slope 1% to 1. The unusual upstream slope was made possible by the stability of the available embankment material, which is composed of a well-graded gravel with the voids filled with earth, sand, and a small percentage of clay. All material was obtained from borrow pits on both sides of the creek channel, an average distance of 172 miles upstream from the dam. The depth of cut in the borrow pits varied from 6 to 10 feet. Pumped water, applied by the irrigation method, ahead of the shovels, wetted the material before excavation. The quantity of water applied at the pit was controlled so that when the wetted material reached the dam, it had the proper consistency for maximum compaction. In general, this consistency was similar to a dry-mixed concrete.

The material was dumped on the embankment in longitudinal rows and spread in layers not exceeding 8 inches in depth. In placing material, each horizontal layer was extended at least 2 feet beyond the neat line of the upstream slope. Each layer of embankment material was then compacted by rolling with 11-ton traction engines, one rear wheel of the engine passing over each square foot of surface at least four times. For a width of 15 feet adjacent to the upstream slope, each layer received at least six passes of the roller. The placing of material beyond the upstream slope of the embankment and the additional compacting provided at this location was done to insure a uniformly firm and stable foundation for the concrete face slab. After each successive 20-foot lift of the embankment was in place, the excess material on the upstream slope was stripped by a dragline excavator and the material replaced in the body of the embankment.

All boulders over 8 inches in diameter which were dumped on the fill were either broken up before the layer was compacted, or removed and placed in the downstream toe drain. No material was placed in the embankment when either the material or the embankment was frozen. The maximum

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