OCR Text |
Show COMPACT-COMMENTS BY A. P. DAVIS A55 and the topography of the side walls at this point are much less favorable than at the site under consideration. The greatest depth to bedrock found so far at Black Canyon is 123 feet. Sufficient borings have not yet been made to develop this site completely, and work is still in progress. The foundation and walls at Black Canyon are described as a hard volcanic breccia, overlaid by flows of latite and andesite. This formation as exposed in the canyon walls is entirely suitable for the construction of a high masonry dam, and unless future borings disclose unexpectedly inferior material in the foundation or excessive depth to bedrock, the site should be entirely satisfactory for the construction of a high masonry dam. The rock in the abutments at the Glen Canyon site is a soft reddish sandstone, unsuitable for building stone or for either coarse or fine concrete aggregate, but probably of sufficient strength to support a concrete dam. Foundation conditions have not been fully tested, the single drill hole then being sunk having on December 15, 1922, reached a depth of 60 feet in the fine sand and silt of the river bed, without having reached bedrock. This drill work is being done by the Southern California Edison Co., and we have no later information as to the progress of this drilling. As to the economy of building Glen Canyon Dam before one at the Boulder or Black Canyon site, attention is called to the fact that Glen Canyon is too far from power markets now available to be of value for power production for many years. For any given capacity up to complete regulation of the stream the height of a dam above low water at Glen Canyon must be greater than one at Boulder Canyon. Taking into consideration the greater distance from sources of supplies and labor, and other unfavorable conditions, a dam at Glen Canyon cannot cost less than a dam of equal capacity at Boulder Canyon, and will produce absolutely no direct financial return for many years. The amount estimated for river control and diversion during construction at Boulder Canyon is $3,500,000. If the Glen Canyon dam cost $50,000,000, as estimated for Boulder Canyon in the table, one year's interest at 6 per cent would practically absorb the savings on the Boulder Canyon dam, and even assuming for the sake of argument that it would cost only $25,000,000, the saving would be swallowed up in two years. Under most favorable conditions power returns could not be realized in any considerable amount at Boulder Canyon in less time than that. |
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Original book: [State of Arizona, complainant v. State of California, Palo Verde Irrigation District, Coachella Valley County Water District, Metropolitan Water District of Southern California, City of Los Angeles, California, City of San Diego, California, and County of San Diego, California, defendants, United States of America, State of Nevada, State of New Mexico, State of Utah, interveners] : |