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LIST OF FIGURES

Figure Titl« Page Frontispiece . ,;

1 Map of the Columbia Basin project lands 3

2 Grand Coulee Dam and appurtenant structures 4

3 Sketch showing the axis positions of three sites 8

4 Location and logs of borrow pit test holes for borrow areas

1, 2, and 3 10

5 Location of borrow areas 4, 5, and 6 12

6 General plan and sections 14

7 Crest and camber details 16 ,

8 General plan and sections of spillway 18

9 Outlet works alinement, profile, and sections 19

10 Gate chamber, shaft, and trashrack structure concrete outlines 22

11 Valve house and stilling basin concrete outline 24

12 Discharge curves for 4- by 4-foot outlet conduit 25

13 Discharge curves for 22-inch-diameter outlet pipe 26

14 Aerial view of Government camp 29

15 Diamond drill operating in cutoff trench 32

16 Cutoff trench after lean concrete had been placed to fill holes

in rock 32

17 Grout machine used in grouting foundation of O'Sullivan Dam 34

18 Sprinkler system for adding moisture to zone 1 material 36

19 Moisture penetration on the face of a 12-foot cut in borrow area 2 36

20 View of borrow area 3 37 . 21 View of east side of borrow area 3 37

22 Placing embankment zones 3, 2, and 1 materials 39

23 Sluicing zone 3 material in place into the embankment 39

24 Hand tamper for compacting zone 1 materials 40

25 Placing the downstream rock blanket on a 2 to 1 slope 41

26 Placing upstream riprap on face of zone 3 material 42

27 Equipment for processing zone 1 material 42

28 Batch plant, mixer, and pumpcrete machine at inlet portal of outlet

works tunnel 44

29 Embankment piezometer installation 46

LIST OF FIGURES (Continued)

Figure Title Page

30 Installing piezometer tubes in dam at closure section 47

31 Cross arm of settlement apparatus in place before backfilling

and compacting 47

32 Embankment settlement installation 49

33 Surface settlement installations plan 50

CHAPTER I--INTRODUCTION

1. General. - The Columbia Basin project is located in the central part of the State of Washington (fig. 1), east of the Columbia River. The primary purpose of the project is the ultimate reclamation of 1, 022, 000 acres of semiarid land in Grant, Adams, and Franklin Counties, in the area known as the Big Bend country, by irrigation with water pumped from the Columbia River. The tract has a maximum width of about 60 miles and a maximum length of 85 miles, reaching from Soap Lake to Pasco.

Settlement of the area began in the 1890's when land granted to the Northern Pacific Railroad was sold in tracts ranging in size from 160 acres to several sections and Government land was opened to homesteading in tracts of 160 acres or less. A series of wet years (1900-1906), when rainfall was above normal, brought about an increase in the settlement activity which extended over most of the good land in the area. However, a few years of normal rainfall showed the futility of attempting to dry-farm any but the better lands in the eastern part of the area. This condition resulted in a large number of foreclosures with the control of large tracts of land passing to banks, mortgage companies, and nonresident owners.

The works for the Columbia Basin project include Grand Coulee Dam, powerplant, and pumping plant on the Columbia River near the mouth of the Grand Coulee, an equalizing reservoir in the channel known as the Grand Coulee, main irrigation canals, a distribution system on project lands, and a conservation reservoir in the middle of the project. Purposes of the project are irrigation of land, power development, and to a minor extent, flood control and improvement of navigation. Figure 1 shows the location of the project lands and the main project works.

2. Grand Coulee Dam and the Power and Pumping Plants. - Grand Coulee Dam (fig. 2) is on the Columbia River about 92 miles by highway west of Spokane and about 266 miles by highway east of Seattle. The structure is a straight, gravity-type, concrete dam founded entirely on dense hard granite. The structure contains 10, 585,000 cubic yards of concrete, and is 550 feet high, 4, 173 feet long at crest elevation 1311.0, 500 feet wide at the base, and 30 feet wide at the top. The spillway in the center of the dam crest is 1, 650 feet long, fitted with 11 drum gates each 135 feet long by 28 feet high, and has a capacity of 1,000,000 cubic feet per second. The spillway crest elevation is 1260.0, the top of the gates in the raised or closed position is at elevation 1288.0, and the maximum water surface elevation is 1290.0. Sixty outlet conduits, each 102 inches in diameter and con

•trolled by two ring-seal gates in tandem, pierce the structure. Eighteen penstocks, each 18 feet in diameter, supply the main turbines, and three penstocks 6 feet in diameter are connected to the station-service units. The total capacity of the outlet works is 353, 000 cubic feet per second, and the penstock capacity is 90,000 cubic feet per second.

Grand Coulee Dam raises the water surface 355 feet and forms Franklin Delano Roosevelt Lake which extends up the Columbia River 151 miles to the Canadian boundary, and 32 miles up the Spokane River. The lake has a shoreline of 600 miles, covers 82,000 acres, and has a total capacity of 9, 517, 000 acre-feet, of which 5, 220, 000 acre-feet are usable.

Above the dam site the Columbia River has a drainage area of 74, 100 square miles. The maximum recorded runoff is 103,000,000 acre-feet for 1928, the minimum 53, 200, 000 acre-feet for 1926, with an average of 75, 116, 000 acre-feet. The maximum discharge is estimated at 725,000 cubic feet per second during the flood of June 1894, with a recorded maximum of 637, 800 cubic feet per second on June 12, 1948. The recorded minimum is 15, 300 cubic feet per second for January 1937, and the 37-year average (1913-50) is 106, 900 cubic feet per second.

The powerplant is located at the toe of the dam and consists of two powerhouses, one adjacent to each side of the central spillway section of the dam. Each powerhouse contains nine units of 150, 000 horsepower each, for a total plant capacity of 2, 700, 000 horsepower. There are three station-service units of 14,000 horsepower each, or a total capacity of 42, 000 horsepower. The total installed plant capacity if 1, 944, 000 kilovoltamperes in the main units and 37, 500 kilovolt-amperes in station-service units. The powerhouses are 185 feet high; the one on the left or west bank is 788 feet long and the one on the right is 737 feet long.

The pumping plant to lift water from Franklin Delano Roosevelt Lake to the Equalizing reservoir is located on a shelf excavated in the rock of the left abutment. The plant is back of a wing dam which adjoins the main structure at an angle of 67°. It has a width of 118 feet, a height of 130 feet, and a total length of 585 feet. The ultimate installation will consist of 12 centrifugal single-stage pumps, each rated at 1, 600 cubic feet per second against a head of 295 feet. Each pump is driven by a 65, 000-horsepower, 13, 800-volt, direct-connected synchronous motor, two motors being supplied with power directly from one generator in the powerhouse. The pumps discharge through 12-footdiameter steel pipes into the Feeder canal leading to the Equalizing reservoir 1. 6 miles away. The discharge pipes are approximately 680 feet long and discharge through concrete siphons with automatic breakers to prevent return flow. The pipes are concreted in tunnels to the top of the abutment and then carried on supports. The lift will vary from 280 to 360 feet depending on the differences between the reservoir surfaces.

The Equalizing reservoir occupies the upper gorge of the Grand Coulee, which is the largest of a series of abandoned channels made by the Columbia River when the river's course was blocked by glacial ice in the vicinity of Grand Coulee Dam.

The upper gorge is an erosional feature 27 miles long, 1 to 3 miles wide, and with almost vertical side walls nearly 1, 000 feet high. Between these walls the irregularities of the original coulee floor have been smoothed over by recent overburdens to give a comparatively level surface.

The Equalizing reservoir, an aritificial lake covering an area of about 27, 800 acres to a depth of 70 feet, is created by the construction of low dams at the inlet and outlet of the coulee. North Dam, at the inlet, is approximately 2 miles west of Grand Coulee Dam. This earth-fill structure has a height of 148 feet (95 feet above the natural channel), a crest length of 1,400 feet at elevation 1580, and contains 1,472,000 cubic yards of material. Dry Falls Dam, at the outlet, is approximately 28 miles to the south and lies immediately northwest of Coulee City, Wash. This dam, an earth-fill structure, is 115 feet high (53 feet above the channel), 9, 880 feet long at crest elevation 1580, and contains 1,605,000 cubic yards of material. The outlet works for the reservoir is on the left abutment of Dry Falls Dam in the form of the headworks for the Columbia Basin Main canal The reservoir has a total capacity of 1, 484, 000 acre-feet and an active capacity of 696,000 acre-feet between elevations 1540 and 1570.

The reservoir serves as part of the main conduit, eliminating the necessity for a very expensive canal along the steep walls of the Grand Coulee. It also allows more efficient use of Lake Roosevelt water for power development and irrigation by providing storage for water which can be pumped when the supply in the Columbia River is ample, and, in turn, decreases the amount of power water required for pumping when the river supply is low.

3. Distribution System. - From the southerly end of the Grand Coulee Equalizing reservoir, the water supply for the irrigable lands is carried, in turn, through a 13, 200-cubic-feet-per-second canal 1.8 miles long (a portion of which is lined), the 1,000foot long Bacon siphon, the 1. 9-mile long Bacon tunnel, and about 1 mile of unlined canal, to Trail Lake. At present, the siphon and tunnel are single barrels with a capacity of 6, 600 cubic-feet per second. The plan calls for duplicate structures to be built when the demand for full capacity is reached.

Trail Lake is bypassed with a 1.4-mile long section of lined canal beyond which a 2. 3-mile long section of unlined canal carries the water to the head of Long Lake, where a 165-foot waterfall is created. Later, when the demand for seasonal power justifies it, a powerplant will be built there, to furnish power for pumping water to the higher lands in the eastern part of the project area. At this point, that is, at the forebay of the proposed Long Lake powerplant, the future East High canal will some day divert a water supply sufficient to irrigate 215, 000 acres in an area now devoted to dry-farm wheat growing. This canal will have an initial capacity of 3,070 cubic feet per second and will ultimately be 110 miles long. It will end in Washtucna Coulee, a few miles east of Connell, Wash.

Water for the remainder of the project passes through the 5-1/2-mile Long Lake reservoir at the southerly end of which is located Long Lake Dam, a zoned-earth structure 1, 900 feet long and 163 feet high. The lake level is raised about 90 feet. A lined

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