72 



THE IRRIGATION AGE. 



REVIEW OF THE WORK ON THE RIO GRANDE 



IRRIGATION PROJECT 



The greatest of all the government irrigation 

 projects is now within a few months of completion. 

 During the coming fall El Paso will celebrate its 

 opening with an international exposition. A review 

 of the project is therefore of great interest now. 



The Rio Grande project, as it is now outlined, 

 consists of a chain of valleys lying along the river, 

 from the Elephant Butte dam, in New Mexico, to 

 the lower end of the El Paso valley, near Fabens, 

 Tex. 



The Palomas valley heads about six miles, the 

 Rincon valley about twenty-four miles, the upper 

 Mesilla sixty-nine miles, the lower Mesilla eighty 

 miles and the El Paso valley 120 miles below the 

 dam. 



The Palomas and Rincon valleys comprise 27,- 

 000 acres, the two Mesilla valleys 83,000 acres, and 

 the El Paso valley 45,000 acres, making a total area 

 to be irrigated in the United States of 155,000 acres. 

 In addition to this, under international agreement 

 with Mexico, the United States guarantees to deliver 

 to Mexico, at the International dam, near El Paso, 

 60,000 acre-feet of water per annum. 



At the present time about 60,000 acres are in 

 cultivation, composed of small strips in each of the 

 valleys. The government has built a diversion dam 

 at Leasburg, N. M., which diverts water to a part 

 of the Messilla valley, and is now building a diver- 

 sion dam opposite Mesilla park. 



In the El Paso valley the government owns and 

 operates the Franklin canal and is engaged in ex- 

 tending and improving this. During the last irri- 

 gation season the Elephant Butte dam was in serv- 

 ice, and at this time has left over from last season's 

 supply about 300,000 acre-feet of stored water. 



This project has been slow in development, 

 owing to international complications, which were 

 not entirely settled until 1907. The development of 

 the project depends almost entirely upon the storage 

 of flood water, as the lands under cultivation in 

 southern Colorado and northern New Mexico ab- 

 sorb practically all of the natural flow, leaving the 

 river dry for long periods in the hottest months. 



The Elephant Butte dam site is about 1,000 feet 

 down stream from a volcanic mountain, known as 

 the Elephant Butte, and twelve miles west of Engle, 

 N. M. The river at this point flows through a 

 sandstone gorge about 400 feet wide at the original 

 river bed and 1,200 feet wide at the high water mark 

 of the reservoir. 



Reconnoissance surveys and borings were 

 started in 1903, but it was not until 1910 that actual 

 construction was started on the spur railroad, which 

 extends twelve miles from a junction with the main 

 line of the A. T. & S. F. railway to the dam site. 

 The ruggedness of the country is shown by the 

 use of 12-degree curves and 3.7 per cent grades in 

 the construction of this railroad. 



Nineteen miles of heavy wagon road construc- 

 tion was required. These roads are constructed 

 with maximum grades of 11 per cent and there is 



little of them that is not on grades of at least 6 

 per cent. 



Construction on the dam itself started with the 

 completion of the flume, in November, 1912, used 

 to carry the river around the dam site. This flume 

 was 1,200 feet long, A6 l / 2 feet wide on the bottom, 

 58y 2 feet wide on the top and 16 feet deep. A drop 

 of over 12 feet at maximum flow was allowed at the 

 intake to permit the incoming water to gather 

 velocity. 



The flume would carry 20,000 cubic feet of 

 water per second easily, and could have been forced 

 to carry nearly 30,000. 



Where the flume crossed the dam site a section 

 of the main dam was constructed, so that the flume 

 structure at this point is now a part of the dam. 

 It was necessary to excavate 81 feet below the old 

 river level before a foundation was found for this, 

 and 25,300 cubic yards of concrete was placed in 

 this section alone. As soon as the river was di- 

 verted through the flume excavation started for the 

 main structure. 



The only sand and gravel in this vicinity is in 

 the bottom of the river, and the only available store 

 place for sand was at the railroad level, 180 feet 

 above the river, consequently it was necessary to 

 hoist the sand and gravel from the river to the rail- 

 road, load it on cars and transport it to a place 

 where it could be stored and reloaded when needed. 



To do this, three cableways were erected, 

 stretching from one side of the canon to the other. 

 These cableways are of 1,400 feet clear span. The 

 main cables are 2% inches in diameter and 1,700 feet 

 long, and are anchored at each end to massive re- 

 inforced concrete anchorages. On the east side 

 they are passed over 80-foot and at the west over 

 125-foot towers, so that they swing 260 feet above 

 the original river bed. 



It was supposed from the diamond drill records 

 that a good foundation would be encountered at a 

 depth of about sixty feet below the river bed. It 

 was necessary, however, to go 101 feet below before 

 the material was satisfactory. 



The total excavation required for the dam will 

 amount to 600,000 cubic yards, of which 161,000 

 cubic yards were stored for use in the concrete and 

 the rest wasted. A large percentage of this waste 

 was shale and rock, encountered below the sand 

 and gravel. 



In June of 1913 a part of the foundation was 

 ready for the first concrete in the main dam, and 

 since that date concrete has been going in every 

 working day. All concrete is mixed in one building, 

 using the sand excavated from the river, sandstone 

 from three large quarries and "sand cement." 



"Sand cement" is a comparatively recent de- 

 velopment which has been used in the Arrowrock 

 dam, Lahontan dam and this one. It consists of 

 commercial cement, mixed very intimately with 

 finely ground sandstone, granite or basalt. 

 (Continued on page 74) 



