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Show BBSS THE OGDEN POST Board to Investigate Boulder Dam Makes Report to Sec. West Committee of Engineers and Geologists Appointed by Congress Last May Makes Report on Boulder Dam Project to Secretary West; Examines Two Canyons and Finds Black Canyon the Best Situated; Makes Estimate of Cost of Project; Stresses Economic Feasibility The board of engineers and geologists appointed under authority of Joint Resolution No. 65, Seventieth Congress, approved May 29, 1928, made its report to Secretary West the latter part of November, and on December 3 the secretary transmitted the report to congress. The resolution provided that the board should examine the dam sites in Boulder canyon and lilack canyon on the Colorado river, review the plans and estimates, and advise as to the safety, economic and engineering feasibility, and adequacy of the proposed structure and incidental works. Major General William L. Sibcrt, United States army, 'retired, is chairman of the board, and the other members are D. W. Mead, engineer; Robert Ridgeway, engineer; Charles P. Rerkey, geologist, and W. J. Mead, geologist. The findings of the report are briefly summarized as follows: Selection of Site The board examined both sites in question, studied the available data concerning them, the geological for motions surrounding them, and the seismic history of the region. At lioulder canyon the foundation rock is granite and associated granitic rock of excellent quality. Regular joints and more irregular fractures are numerous and there is an occasional fault zone.' Test tunnels prove that these are of little consequence to within a few feet from the surface. On the whole the rock is strong, substantial, durable, and the whole mass is essentially tight. There is no danger of the rock failing to meet requirements as a dam foundation. The rock in the vicinity is suitable for construction materials, and there are local sources of good gravel. If no other site was available, the Boulder canyon site could safely be used as far as 7 geological conditions are concerned. 5 The most favorable site in Black ' canyon is about 40 miles distant from Las Vegas, Nevada, and the Union Pacific railroad. A construction railroad from Las Vegas would pass near available gravel deposits and the best quarry sites. The foundation is a volcanic breccia or tuff, a tough, durable mass of rock standing- with remarkably steep walls, and resisting the attack of weather and erosion exceptionally well. The rock formation is somewhat jointed and exhibits occasional fault displacements, which are now completely healed. It is almost ideal rock for tunneling, is satisfactory in every essential, and is suitable for use in construcwell-cement- - tion. Geologic conditions at Black canyon are superior to those at Boulder canyon. The Black canyon site is more accessible, the canyon ,is narrower,, the gorge is shallower below water level, the walls are steeper, and dam of the same height here woult cost less and would have a somewha greater reservoir capacity. The rock formation is less jointed, stands up in sheer cliffs better, exhibits fewer open fractures, is better healed where for merly broken, and is less pervious In mass than is the rock of the other site. There is no doubt whatever but that the rock formations of this site aye competent to carry sainely the heavy load and abutment thrusts contemplated. The board is of the opinion that the Black canyon site is suitable for the proposed dam, and is prefer able, to Boulder canyon. Danger from earthquakes and deformation The district is recognized as having comparative freedom from present-da- y earth movements, and the conclusion is that danger from local earthquakes of enough violence to threaten a properly constructed dam in Black canyon is negligible. is not feasible to construct the rock-fi- ll cofferdams, excavate to bedrock, prepare the foundation, and place concrete for the permanent cofferdams season of leBs than in one nine months without undue risk to the men working in the excavations and inhabitants of the valleys below. It is further of the opinion that the proposed diversion is inadequate and that provision should be made for diverting around the dam site, through tunThe nels, at least 200,000 second-fee- t. height of water against the upper cofferdam Bliould be limited to about 55 feet above low water as a measure of safety. in Permanent spillway. Water should not be permitted to Juantity a dam of this height A permanent spillway utilizing the increased capacity of the diversion tunnels provided in the revised plans will make it practicable to prevent any ex preted flood from overtopping the low-wat- er Interest during1 construe tion on above Total In this revision, stresses in the dam have been limited to a maximum of SO tons per square foot, and a diversion capacity of 200,000 second-fee- t is provided. If canal to Coachella Valley is considered part of the main canal, add 10-ye- ar 11,000,000 Total estimated cost for all items in II. R. 176,000,000 These estimates are based on a con6773 struction period of seven years. Adequacy of Proposed Structures A dam of 550 feet above low water across the Colorado River at Black canyon will be adequate in the boards opinion so to regulate the flow of the Lower Colorado as to control ordinary floods; to improve present navigation possibilities; and to store and deliver the available water for reclamation of public lands and for other benefi cial uses within the United States. Water Supply of the Colorado River The board estimates the flow at Black canyon, without further depletion, as follows: Acre Ie ,ncs 50-ye- 5rlih maximum a. calculated 30 tons perl stresses not foot. This will add material square i tn the cost of the structure. and river diversion. t tie river dur- - I et an an Lights,, Water, Signs Promised for Airport Much-neede- improvements at were virtually assurred Tuesday when a three-fol- d improvement program was formulated and adopted at the Exchange club lunch eon at, the Hotel Bigelow. Mayor Frank Francis, speaking for the city commission, stated that an adequate water supply and prone? lighting of the field will be done by the city during the coming year, and the Exchange club voted to have large signs designating Ogden painted on large rooms both within the city and in the western portion of the county Arrows pointing out the direction to the airport would also be included in the signs. A special sign committee was appointed, consisting of Burton F. Dinsmore, Ronald Wadsworth and Robert Folland. Joel Nibley of Salt Lake, a director of the National Parks Airways, was the principal speaker and said that great development in aviation could be expected both in Salt Lake and d Ogden Air-po- rt X WAJ iV. ;isi ar hs (26,-000,0- 90 gllPPKVWTrWTW et l,000,0th)-horsepow- er an 1 r (Ca IPdDwer, Speed and Smoothness at a price you're glad to pay Cmtpm, IMS, Bod, by IfaJW Come see and drive the New Pontiac Big Six. It offers big car and power, speed 26,000,- ia the judgment of -- houid w ih hs six-tent- hs 50-ye- ar et e 11 five-tent- ar operation, maintenance, interest, and sufficient sinking fund to retire the cost of the project within a period. 4. If the income from storage can be reasonably increased and the capi. tal investment reduced by the cost rf the canal, together with a reduction for all or a part of the cost properly chargeable to flood pro. tection, it would be possible to amor tize the remaining cost with the in! come from power. an the maximum stresses qllow- exceed those adopted l0Ji0t V, practice. The proposed dam structed and would impound - edr1 50-ye- 1929 et canyon that will safely impound water to an elevation of 550 feet above low A dam of the gravity . type ite in nrot??!? f watcr Feet Average low flow for a per- - , JO, 000, 000 iod of 15 to 20 years Average high flow for a similar period .... . . 14,500,000 Average of high and low 12,250,000 periods It is estimated that the present flow is depicted by water taken for irrigation in the upper basin by apwhich proximately 2,750,000 acre-fee- t, amount, if added to the above estidam. mated average flow, would increase Excavation for main dam. It is the it to about 15,000,000 acre-feThis judgment of the board that it is feas- is the amount apportioned by the sev ible to make the required excavation en States compact for division at for the permanent dam, but it is their Lees Ferry. opinion that plans and estimates of Mineral Salts in the Reservoir cost should include provision for the The waters of the Colorado are norcontrol and handling of a considerable volume of water seeping into the ex- mally high in dissolved mineral salts, but the amount is well within the cavation. limits of accepted practice for irrigaPower Plant While a power house must be fitted tion purposes. The waters impoundto a particular site and its equip- ed in the Black canyon reservoir ment must be designed and selected would overflow, to a limited extent, for the particular conditions existing lands in the virgin valley that conat that site, the entire installation will tain beds of soluble salts. It is the nevertheless be largely standard, and opinion of the board that the actual offers no particular difficulties. The salt content will not be increased to an injurious amount, even in the beplans proposed are feasible from an and that, in a comparatively ginning, engineering standpoint. short the incoming silt will be time, Canal soa effective in blanketing the salt deThe bill provides for the construcposits that the salt content of the tion of a canal connecting Laguna river waters will be reduced to about Dam with the Imperial and Coachella the present amount Valleys. The main canal would be 75 Silting of the Reservoir miles long, entirely within the UnitThe best determinations available ed States, and for a section of 10 miles, would cross a region of sand indicate that silt deposition in the dunes. Although difficulties are pro proposed reservoir would be at the sented by the drifting sand, the board rate of approximately 137,000 acre-fefinds it is entirely feasible to conper year. At the end of the struct, maintain, and successfully op- first' period there would still erate the canal. The board believes be available approximately three-fourtof the effective reserve cathat the canal should be lined with concrete through the sand-dun- e re- pacity for irrigation and power and gion, and should be given a slope suf- a slightly larger proportion of the ficient to carry the inblown sand to flood reserve capacity. It would take suitable place for deposit and re about 190 years to fill the reservoir with silt providing there is no addi moval. tional upstream reservoir development Estimates of Cost A review of the etimates for the resulting in reduction of the rate of proposed structures resulted in the silt delivery. board reaching the conclusion that River Silt Below the Dam these estimates should be modified as With the continuous regulation of follows: river flow afforded by the proposed Dam and reservoir reservoir and the virtual elimination acre-fecaof high flood waters a tendency to pacity) $70,600,000 silt stabilization will follow. Ultimate, dely the silt content will be virtually ... 38,200,000 eliminated. The board believes that velopment canal $38,500,000 marked improvement will be shown T11 such a structure would causefailure of damage to The' coSnt lhe dam hou,d be construct- - by virtue of its location, first call on the water of the river. The withdrawal of the allotted share of the annual flow during any series of imyears of low flow1 may make it of gated lands. Thereafter improvement terms acpossible to carry out the will be gradual, though erratic, on the compact during the latter part of count of occasional floods. a low period. If the low flow Power continued for a considerable term of It is believed that under present years, the proposed storage at Black conditions of irrigation a continuous canyon would be inadequate to prooutput of 650,000 horsepower, or vide sufficient water for the lower horsepower on a 55 per cent basin through such a period. The load factor, could be maintained even power output would also be seriously during the years of normal low flow. affected and might be reduced below As the use of water for irrigation in- the estimated minimum previously creases, the amount of water available stated. With the uncertainties of the for power will decrease and a time flow at the Boulder Dam it is imwill arrive when, during periods of possible to estimate closely the avelow water, the full estimated amount rage annual output of power which of power can not be maintained. would obtain during a perWithin a 30 or 40 year period, even iod. with aoregulating reservoir, the power Economic Feasibility output may be reduced to In the economics of this the of the considering of or capacity improposed plant during a long dry per- project, the board recognizes the folof the others, iod. portance, among The whole matter is further com- lowing factors: 1. It is of much economic importplicated by the proposed seven States It is quite probable that ance that an agreement limiting the compact. the compact attempts .to apportion amount of water assignable to Mexmore water than the actual average ico should be made prior to the comThe pletion of the Boulder Dam project. undcpleted flow of the river. still is further situation 2. The board believes that the complicated by the fact that the upper States are growing demand for power in Southauthorized to take more than an equi- ern California, when considered on a table proportion of the flow of the conservative basis, will be sufficient river, for any one or more of a series to absorb the probable power output of dry years, provided they permit of the proposed hydroelectric plant. to flow a total of 75,000,000 acre-fe3. If the Boulder Dam project is down the river in a period of 10 con- completed and put in operation, carsecutive years. rying as it does the costs of flood First Call on the Water )rotection works and the In any event, the upper basin has, canal, it will be impossible to meet within the first 10 years, especially 17,700,000 in reduction of the amount of extremely fine suspended silt, which at 165,000,000 present causes most damage to irri- MilIe from an engineering standpoint to build a dam at Black fr Friday, February 1, - smoothness at a price youre glad to Here, truly, Is a new idea in low cost pay motoring luxury! A car conoehcd, designed and built for tboae who want something more the cheapest and who choose to reveal their progressive ideas in better ears as well as better homes and better furniture. What a reception these buyers are giving the New Pontiac Big Six! 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