Engineering by Land and Sea.

Progress, Volume VI, Issue 9, 1 July 1911, Page 723

Engineering by Land and Sea.

Highest Dam in. the World. ■ :fJPrnm n a • rnTFP#nnn -j n ( ° m ur n c CoiresponJent.) Skoskone Irrigation Enterprise. T S . , P ,/r ’ os Angeles, may 10. ■ The Government has added another sprig of laurel to its wreath of victory by building the highest dam in the world, Incidentally it has waved the magic wand for an additional flourish and a vast tract of land, parched and unproductive desert, lost in the wild eddies of rugged mountains, _ has thrown off a lethargy and is blooming as the valley of the Nile. In this desert are being planted towns that are to be cities. Thought is being given to the future, and they are being laid' down for posterity for a hundred years to , come.

years’ task, at which men had worked three shifts, night and day, was completed, and in this wild canyon had been placed an additional monument to the prowess of America, a monument that is intended to last for ever. The dam, 328 feet high, measuring from bedrock, 48 feet higher than the Flatiron building, and containing enough material to build a hundred like it. Yet so precipitous were the walls of the canyon, rising half a mile above the stream almost perpendicularly, that they were about 200 feet apart at the top of the dam. The base of the structure, measuring up and down stream'is 108 feet. This width decreases gradually towards- the top, forming a-parapet-only as wide as. a waggon road. The Croton dam, which supplies water to

into these to weld itself with them. The Government prosecuted the work alike in summer and in winter weather. The structure was heated by steam pipes and encased in a canvas covering that damp cement might not freeze and crack in winter. All the material came over a road blasted into the cliff side, for only the mountain goat might find secure footing here. The immense structure was built as in an arch laid on its side, with the top turned upstream. The arch is a bearer of great weight. Immense buildings in all the cities rest upon arches, This dam is to bear great weight, but the pressure is to come from the waters that are impounded behind -it; Therefore, the top of the arch is turned upstream,’ and all the pressure that bears against it will

. Each is being modelled after Washington, the_ Capital City, and the only munieipality ever built with the far future, in mind. A score of little Washingtons are being planted in the West by the Reelamotion Service, but the latest of these is Powell, under the great Shoshone dam. The announcement of this project’s completion has just been made. When the snows of Yellowstone Park melt this spring and _ rush, as they usually do, into the precipitous gorges thereabouts, they will find one outlet blocked. Across the great Shoshone Canyon there stands a bar of masonry that will effectually block the progress of these rapid waters. They will be halted and imprisoned, and when the time comes that they can serve man well they will be led to the near-by plains and set to work doing his will. In the big Buffalo Horn Basin, where the buffalo made its last stand, the plough will have opened a iuitow xor me waters to iouow, and alfalfa will be set to grow where a score of years ago “Buffalo Bill” rode forth in buckskins to shoot big game. A month ago the huge cranes lifted the last bucket of concrete to the top of the dam at Shoshone, a lever was pulled and the substance spilled over the mould which represented the completed dam. A three

Denver, had hitherto held the record for height, it mounting up the 300-foot mark. Long since had America passed the altitude of the Assuan Dam in Egypt, once regarded as a world’s wonder, and lacking 100 feet of the height of the Shoshone. The engineering data for complete project is Reservoir, Shoshone— 6600 acres; capacity, 456,000 acre-feet; length of spillway, 300 feet; elevation of spillway, 233 feet above stream bed. Storage dam, Shoshone—Type, concrete arch; maximum height, 328% feet; length of crest, 200 feet; contents, 69,000 cubic yards. Diversion dams, Corbett—Type, reinforced concrete ; maximum height, 18ft.; length of masonry, 400 feet; length of earth fill, 440 feet. Length of canals—l 3 miles with capacities greater than 300 second-feet; 21 miles with capacities less than 300 and greater than 50 second-feet. Aggregate length of tunnels, 19,000 feet. The new structure has been so pul up as to become one solid rock, and to form a part of the cliffs on each side, just as though it had been placed there in geologic times as a part of them. It is a solid concrete mass. Its feet are driven far. into the bedrock that underlies the stream, Great ditches were cut into the sides of the cliffs, and the concrete was poured

but have the effect of making it more solid, When the waters are stopped here a lake will be formed that will cover ten square miles of surface, and have an average depth of seventy feet. This will amount to the storage of 456,000 acre-feet of water, or enough of it to cover the entire state of Rhode Island to a depth of one foot. The artificial lake will take the place of a natural one, which existed there in prehistoric times, before the stream cut its way through these cliffs and ate its way down. It will be fed by streams that abound in fish, and its shores will be visited by things of. the wild from the country round about, a country that has felt the hand of man less than any other section of the United States. It will be the Mecca of sportsmen and an outing resort equal to those of the Alps. The dam will stop the waters and hold them for ever. But its usefulness depends upon supplementary works. Into the cliff on one side near the base plunges a tunnel in. the solid rock, guarded by gates of iron, so big and heavy as to weigh 10,000 pounds each, and to require an engine to lift them. It is the purpose of these gates to let the desired amount of water back into the stream that it may find its way to the diversion dam lower down and

eventually into the canals which lead to the open plains. Thus the dam catches the flood waters and holds them for timely distribution through the tunnel, leading them on to lands that may be irrigated. Then on the other, side of the dam near the top is another great tunnel through the solid rock. This is meant as a spillway for the flood waters. When the freshets raise the water mark to a position anywhere near the ■ top of the great dam the flood gate will be opened into this tunnel, which is 20ft. across and built with a fall of 40deg., and these waters will plunge through the mountains with such a roar as to shake the earth. This arrangement for the storage of the waters, the disposal of flood water and a leading to usefulness of that water that is to serve a purpose, completes the scheme in so far as the great dam is concerned. But all this is done for the sake of the result that will be brought about in the basin below. The Big Horn Basin lies 60 miles further down. Here the sediment of the ages has washed down from the mountains

round about, and filled in the depression until it is as smooth as a floor, but slightly tilted. There are mountains on all sides of it protecting it from storms, and pushing their peaks into perpetual snow. The Yellowstone Park is but 76 miles to the west, and the town of Cody, near by, is one of the points from which tourists start the overland trip to that great wonder. Yet the region outside the far-famed park differs but little from it and offers wonders of its own that appal those who visit it for the first time. Since the buffalo disappeared from the Big Horn Basin there has been little use made of it other than the pasturage of an occasional herd of cattle or sheep. It has slept perenially beneath the sun, and harboured its latent productiveness against the time when man might divert the waters ot the Shoshone and irrigate it. The rainfall has not been sufficient to produce any manner of growth. Neither have the waters flowed over it to dissolve the salts of the soil that mean great fertility should plant life ever be brought to grow here. The latter fact accounts for the superiority

of these desert lands over the soils of other regions where rain is more plentiful and where the life is .washed out of the soil by too much water. The reclamation service has . diverted small amounts of water into the basin before the completion of the reservoir, For the past three years the Government has thrown open for settlement 15,000 acres each season, and has provided a water supply sufficient for the irrigation of these tracts from the regular flow of the river. They have been absorbed by the land hungry from many States, and new homes and new towns have sprung up. Ralston and Garland were two such towns, The latest village to be born in the basin is Powell, now a rapidly growing infant city of one year. All are located along the Burlington Railroad, which traverses the basin. It is in these new towns that thought is being taken of the future, and a town is being grown to order, a thing that has happened but a few times in the history of the world. Powell is the best example of

this taking thought. - The reclamation service realises that when it opens up a new tract of intensely fertile land, many towns and cities will develop with a probability of sometime becoming greatly populated. It is, therefore, giving thought to the manner in which the ground plan of a city should be laid out. It appreciated the fact that Boston is labouring under the handicap of a maze of streets that are without system and that grew up from the footpaths of the early settlers. There is the one American example of a city laid out with the idea in the beginning that it was to grow into considerable proportions— city of Washington, which is the prettiest and most conveniently laid down municipality in the world. The new towns on the West are being laid out on an almost identical plan. As Washington began with the Capitol building, these begin with the public square containing the schoolhouse. From this, at right angles, extend streets in accordance with the cardinal points of the compass. In the wide right angles of these streets are run diagonal streets in the same way

that the capital city ran its avenues named for the States.

The near-in lots are small and' intended as business sites. Those a little further cut are larger and meant for residences, with a yard and garden V around them. Still further out the subdivisions are yet larger, amounting to five acres at a distance of a quarter of a mile. A hundred and sixty acres is set aside as a town site, and/* the lots are divided in this manner and sold at auction. The map of the future town is in this way absolutely controlled by the men who lay it out. But the Government goes still further and lays the surrounding country in a similar plan. Within a mile of the town site no individual is allowed a tract of more than forty acres. This means that to every square mile there will be not less than sixteen houses, a density of settlement that makes the community almost a village throughout. Outside the mile limit no settler may acquire more than eighty acres of land. There are few of the prosperous farming communities in the best of the eastern States that have a family on each eighty acres.

The irrigated country lends itself to the working out of an ideal manner of life. There the individual needs but a small amount of land to produce a competence. This means that the homes will' be close together and that the bane of country life, its isolation, will be done away with. ‘The neighbours will be sufficiently : close together to ■ maintain - high-class, - graded schools, to get rural free delivery,- party telephones, to maintain- - good churches, social life, and libraries. The new-planted town of Powell is just taking this form. Already it has' the central school, a church, the nucleus of a business section. The Government refuses to sell additional land until a given radius is settled ; up to the prescribed density. The system of its subdivisions will dove- ■ tail into that of the. near by towns which are similarly built. The roads meet exactly those from adjoining communities. Water is distributed to these people, and their existence depends, on the operation of the laterals. These are in the hands of a farmers’ organisation which draws all the members together in a community of interest. This has already developed along .other practical lines. The farmers found, for instance, that if they would guarantee to produce a given number of “carloads of potatoes, they could contract them to good advantage to big dealers. The organisation asked what farmers intended raising potatoes, and to what extent. The report furnished a basis for an agreement and sales were made in advance for good prices. The farmers in these communities are co-operating on the sale of all their products, a thing rare, but much needed in all such communities.

The completion of the Shoshone Dam means that this kind of farming may be extended to 150,000 acres, of land as soon as there are settlers for it. This means-a homes for 30,000. productive people. Tim Government will extend its canals each year to a sufficient extent to take in as much land as there seems a demand for. Just now there are 300 farms going begging at Powell, because there are no takers on the ground. When these are . settled up there will be an additional number put on the market. The land still belongs to the Government, having been withdrawn

from settlement when the project of reclaiming it- was begun, that it might be dealt out just the right way through the reclamation service to actual settlers and not pass into the hands of large owners. The land was previously worth absolutely nothing, but as soon as it is irrigated it immediately acquires a value of £3O an acre, and yields returns that mean a handsome interest on an investment of that V-size. The principle of all the projects is the same.

■The reclamation fund comes from the sale of Government land in the West. All money taken in by the Government from that source is to be used for the purposes of reclaiming desert land. It is, however, - but an advance on the part of the Govern- * ment which will eventually get all the money back. All expenses of the Government in building reservoirs and canals are charged against the land. The farmer is to pay it in ten equal, annual instalments. In the Big Horn Basin, for instance, the farmer must pay £1 2s. an acre per year

for his water. This pays for the maintenance of the project and one-tenth of the construction cost. In ten years he has paid off the original charge against the land and has to pay an amount sufficient to maintain the project, probably less than Is. an acre.

The amounts may seem high to the man unfamiliar with irrigated lands, but as a matter of fact the returns from these lands are so great that the assessments may be easily met.