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Show The evaporation from the surface of the lake, " based on the results of an observation station at Hid Lake and one at Airport, averaged 5.657 feet of fresh water per year. Messrs. Fox and Keller, in a thesis written for the University of Utah, have calculated the evaporation of the salt water to be 4-• 667 feet. The maximum elevation of the lake was reached in 1872, when, according to traditional information, it reached an elevation of 4,212 feet* Since I89O accurate records have been kept and the maximum elevation which was reached in May 1924 was 4,205 feet. This is the elevation of the meander line of the lake. The maximum variation in the level of the lake for any one year has been 3* 3 feet; the minimum has been 1 foot; the average 1.8 feet. It is contemplated that the dikes will hold the fresh water to the elevation of 4,205 feet. This will, of course, prevent flooding low lying lands above the meander line and maintain a nearly constant level, so that factories, pumping plants, etc., which are near the beach will not be forced to dig canals and lay pipe lines in order to keep supplied with fresh water. Regarding the dikes themselves, I have assumed an elevation of 4,210 feet, U. S. G. S., for the top of the dike or 3.5 feet below the top of rails of the Southern Pacific Railroad. This will allow five feet in the clear vertically above the fresh water side and due to a 20 to 1 slope, 100 feet horizontally. Should the lake appear to rise to a point where this elevation is dangerous it would be a simple matter to add enough material to the top of these dikes to take care of the situation during - the period when the lake is at its maximum height. Using a slope of 20 to 1, which should be sufficient to eliminate any danger from ice on the fresh water side, and break up the heavy waves from either side at a sufficient distance from the top of the dike to eliminate any possibility of the material being washed away during a storm, or parts of it carried away during the winter when the ice has a tendency to accumulate. Assuming then an elevation for the top of the dike of 4,210 feet, the North dike would average 22* 1 feet in height and be 18,250 feet long and contain 6,620,940 cubic yards of material. The middle dike would average 25* 3 feet in height by 29,300 feet long and contain 13,538,954 cubic yards of material. I have been informed that a short distance east of the line indicated on the map, water is much more shallow and it is quite possible that by lengthening the dike somewhat a material saving may be made by moving the dike slightly to the eastward. This would not in any way affect the general plan of the project. The . South dike would only average 9* 8 feet in height, 13 » 900 feet in length and contain 1,344,546 cubic yards of material, making a total of 21,504,440 cubic yards. I have been informed by the Ellicott Machine Corporation of Baltimore, Maryland, that dredges capable of doing this work may be constructed on the lake and the total cost of the material in place, which would include amortization of the dredges over the period necessary for construction and all other expenses, will be 5^ per cubic yard. If this is the case, the project should cost approximately $ X, 075,000.00. The Ellicott Company sent their San Francisco representative here to check this cost. Many engineers have stated that a 10 to 1 slope would be sufficient to accomplish this same purpose. If this is the case, a total of 11,713,775 yards would be necessary and the cost would be 0585,689.00. - 22 - |