To the Senate and House of Representatives:
I submit herewith the report of the engineers appointed by me to accompany the ex-Secretary of War, the Hon. William H. Taft, to the isthmian canal to look into the condition of the canal work, and especially to report upon the feasibility and safety of the Gatun dam project, with a view to deciding whether or not there should be any change in the plans in accordance with which the canal is being constructed, these plans having been adopted by the Congress. I am happy to report to you that the accompanying document shows in clearest fashion that the Congress was wise in the position it took, and that it would be an inexcusable folly to change from the proposed lock canal to a sea-level canal. In fact this report not only determines definitely the type of canal, but makes it evident that hereafter attack on this type--the lock type--is in reality merely attack upon the policy of building any canal at all. The board of engineers who signed this report are of all the men in their profession, within or without the United States, the men who are on the whole best qualified to pass upon these very questions which they examined. I commend to you the most careful consideration of their report. They show that the only criticism that can be made of the work on the Isthmus is that there has sometimes been almost an excess of caution in providing against possible trouble. As to the Gatun dam itself, they show that not only is the dam safe, but that on the whole the plan already adopted would make it needlessly high and strong, and accordingly they recommend that the height be reduced by 20 feet, which change in the plans I have accordingly directed. Every American citizen should feel not merely gratification, but a very keen sense of pride in the statement made by this distinguished body of engineers as to the way in which the work has been done, and in which it is now proceeding. The American people are to be heartily congratulated on everything of importance that has been done in connection with the building of the Panama Canal.
THE WHITE HOUSE, February 17, 1909.
WASHINGTON, D.C., February 16, 1909.
SIR: In accordance with your instructions, we have visited the isthmian canal, in company with Hon. William H. Taft, and have examined the work in progress and the plans for the structures as far as now developed.
We have given especial consideration, under the instructions of Mr. Taft, to the foundations for the Gatun dam, and the feasibility of constructing and maintaining thereon a safe dam for retaining water at 85 feet above sea level.
We have examined the slides in the banks of the canal and the surveys, plottings and sections that have been made of them. The subsidence in the fills in the toes of the dams and in the railway embankments has also been examined, and we have considered the effect of the qualities of materials thus disclosed upon the construction of the various works and upon their ultimate stability.
We have also considered the evidence that has been accumulated as to the permeability of the different materials and the possible loss of water by percolation through the bed and banks of the future Gatun lake; and the question whether such loss of water by seepage would result in materially reducing the water supply or in undermining and ultimately crippling the structure.
The Gatun earth dam is the central point of discussion, and we were instructed by Mr. Taft to give it first consideration in the light of all new evidence.
We are satisfied, both from the records of the experiments that have been made and from our own personal examination of the materials, as seen in cuts now open and as disclosed by samples from test borings, that there will be no dangerous or objectionable seepage through the materials under the base of the dam, nor are they so soft as to be liable to be pushed aside by the weight of the proposed dam so as to cause dangerous settlement.
We are also satisfied that the materials available and which it is proposed to use are suitable and can be readily placed to form a tight, stable and permanent dam.
The type of dam now under construction is one which meets with our unanimous approval. It is a combination of rock fill and hydraulic fill, in which the exterior faces are to be composed largely of rock of all sizes obtained from the canal excavation, dumped and laid on slopes much flatter than are ordinarily found in earth dams, while the interior of the great mass will consist of clayey material obtained by hydraulic dredging from large deposits at a little distance from the dam and carried by water through pipes to the places where it is to be used. The material as delivered is a mixture of earth and water. The material held in suspension slowly deposits, finally forming a solid, water-tight embankment. The pond necessarily maintained on the top of the dam during construction tests the embankment at all stages of its growth, searches out any weak points, and leads to the closure of any voids or cracks.
The most practical question in the construction of the Gatun dam is the possible slipping and sliding of the materials underneath and in the body of the dam. The materials, speaking broadly, are of a clayey nature, generally impervious to water, but sometimes slipping when subjected to heavy unbalanced pressure or on high steep slopes when saturated with water. In this respect the materials differ radically from the sandy and gravelly materials which have been frequently used in the construction of other earth dams.
In order to build a dam of these clayey materials that will be stable and permanent, it is necessary that the slopes should be flatter than would be needed to secure the stability of a dam of siliceous, sandy, or gravelly materials.
The evidence that has been accumulated as to the degrees of slope that are stable with these materials seems to us conclusive. The fact that the materials are slippery does not mean that a dam built from them is necessarily less stable than a dam built of materials that do not slip so easily. It does mean that, in order to secure stability and permanency, the dam must be built with a greater thickness at the bottom.
The dam as proposed is more than a third of a mile in horizontal thickness at its base, including the rock-fill portions.
The design upon which the work is now being prosecuted abundantly fulfills the required degree of stability and goes far beyond the limits of what would be regarded as sufficient and safe in any less important structure.
As a matter of convenience and economy during construction, materials have been piled up on slopes much steeper than those contemplated in the finished work. Generally, the materials so placed have remained in position, but in some cases slips have occurred. The occurrence of these slips is of no serious consequence either in the practical execution of the work or in the ultimate stability of the structures. We can readily understand how incorrect deductions may have been drawn from these occurrences, especially by those not fully informed as to the character of the materials and the ample dimensions and much less steep slopes of the proposed structures in their final form.
We were requested to consider the proper height for the crest of the Gantun dam, and after consideration concluded that it could be safely reduced 20 feet from that originally proposed, namely, to an elevation of 115 feet above sea level, or 30 feet above the normal level of the water against the dam. We are also of the opinion that the sheet piling recently proposed under the base of the dam may be safely omitted. The narrow cut-off trench now in progress through the upper earth stratum on Gatun Island and elsewhere and designed to be refilled with sluiced material should be continued.
Changes in these respects will facilitate the work of construction and will reduce somewhat the cost of the proposed work.
A full study of all the data at hand, and of the materials, and of the plans that are proposed with the above modifications leaves no doubt in our minds as to the safe, tight and durable character of the Gatun dam.
CHANGES IN PLAN OF CANAL.
It was suggested to us by Mr. Taft that we give special consideration to those changes which have been made in the plans of the minority of the Board of Consulting Engineers of 1905 since the adoption of the project.
Change in position of lower Pacific locks.
One of the most important of these changes is the moving of the lower locks on the Pacific end of the canal from La Boca, on the shore of Panama Bay, to Miraflores, about 4 miles inland.
This change involved abandoning the construction of two earth dams at and near La Boca and the substitution of about 4 miles of deep-sea level channel 500 feet wide from La Boca to Miraflores in place of a wider channel through the lake that would have been created by the dams.
Before this change was made work had been commenced upon the toes of one of the dams. The material had been piled up to a considerable height on slopes steeper than were capable of being supported by the underlying material. Under these conditions settlements occurred with lateral displacement of some of the underlying material. Your board, after carefully inspecting the ground and the partially completed work, is of the opinion that these settlements cause no reason to doubt the stability of the Proposed dams. We are unanimously of the opinion that stable and water-tight dams of substantially the proposed dimensions could have been constructed on the proposed sites without recourse to dredging out the underlying soft material.
The report of the minority of the Board of Consulting Engineers of 1905 recognized that an objection might be made from a military point of view to placing locks on the shore of the bay, exposed to guns of hostile ships. We now understand that the controlling reason for the change was a military one. This change in the plans will result in an increase in cost of the canal by an amount judged from evidence at our disposal to be not less than $10,000,000. We are informed, however, that this change would greatly lessen the cost of fortification.
Increased width of canal
Another change is the increase of the minimum bottom width of the canal from 200 feet to 300 feet. This applies to a length of about 4.7 miles in the Culebra cut. We understand that this change will increase the cost of the work by about $13,000,000. The work upon the excavation of the Culebra cut under the revised plan has now so far advanced that this widening will not delay the completion of the canal.
The widening will permit ships to pass one another in this portion of the canal, as they may under the original plan in all other portions, and will otherwise facilitate navigation through it.
If slides occur after the completion of the canal, the wider canal is not as likely to be blocked as a narrow one.
We understand that this change was authorized directly by you on the Presentation of its advantages by the chief engineer, and we merely call attention to it as one reason for the increased cost of the canal.
Increased size of locks.
Another change is the increase of the dimensions of the locks from 95 by 900 feet to 110 by 1,000 feet. The increase in width we understand has been made in compliance with a request from the General Board of the Navy Department, in order to allow the passage of the largest war vessels contemplated.
A large increase in cost is involved in these enlarged dimensions.
Changes in breakwaters.
An important change is proposed in the location of the breakwater at the Atlantic end of the canal. The plan provisionally adopted by the Board of Consulting Engineers of 1905, and adopted for the purpose of estimate by the minority of that board, was for a breakwater generally parallel with the channel, which included less than one-third of Limon Bay; whereas the breakwater in the location now proposed will protect the entire bay and furnish a more commodious harbor not only for ships using the canal, but for all other shipping which makes use of the port. A considerable increase in cost is involved in this change.
We had an opportunity to view the present harbor during what is said to have been the only severe norther of the past two years, and have no doubt that a good breakwater is a desirable adjunct to the canal. We are not prepared to pass on the precise location, form, or cost of this.
A change of less importance has been made at the Pacific end by relocating the dredged channel leading to deep water and increasing its width from 300 feet to 500 feet and by constructing a breakwater from the shore at La Boca to Naos Island with material excavated from the Culebra cut. This breakwater, now under construction, serves to prevent currents across the canal cut and tends to prevent deposits in the dredged channel and to increase the safety of navigation. The breakwater may also serve to carry a roadway to Naos Island. These changes involve some additional expense.
Relocation of Panama Railroad.
The alignment of the Panama Railroad has been materially changed south of Gatun. This change was made because it was found that the swamp near the Gatuncillo River would not support the very high railroad embankment required, if made with ordinary slopes, and a line crossing at a point higher up the river was selected, which does not, however, materially increase the length of the railroad. The construction of the railroad will cost much more than was estimated by the minority of the Board of Consulting Engineers, who were unable to procure surveys of the proposed location. The recent change in location affords more ample and convenient anchorage immediately above the locks.
Some further changes or additions which have not yet been fully worked out have been mentioned to us as likely to be made as the work progresses, namely, the dredging out of a broad anchorage basin immediately downstream from the Gatun locks, another for anchorage and room for turning of long ships near La Boca, and possibly another just below the Miraflores locks. These can all be delayed until the completion of the main work of canal excavation and lock building, and then executed by the dredges that have done the main work. The work can thus be done without additional equipment, and at a low price per cubic yard.
PRESENT CONDITION OF WORK.
It has been suggested that we report upon the condition of the work and the progress being made, and, if found possible in the time at our disposal, upon the probable time of completion.
We have seen the work under way on all parts of the canal. We have become acquainted with the engineers in responsible positions and have noted the organization and equipment.
It is our impression that the work is well organized and is being conducted energetically and well.
The work is done by day labor and not by the contract system.
The men are well paid, well housed, well fed and well cared for in case of sickness or accident. Houses, furniture, fuel, water, drainage and lights are furnished to employees without cost. Roads are built, schools supported and Young Men's Christian Association buildings provided, which are practically club buildings. Parts of the running expenses are also paid. The premises are cleared and drained and the grass kept cut. The climate is especially adapted to outdoor life, and the ample porches, entirely inclosed by bronze-wire screens, give the greatest facility for this. We are especially pleased with the architectural arrangements of the houses. They are admirably adapted to the climatic conditions.
Bachelor quarters and hotels furnishing meals at moderate prices are also provided by the Government.
Hospitals are provided, free medical attendance is furnished to employees and medical attendance at low rates is supplied to families of employees.
A limited amount of free transportation, namely, one excursion trip each month to any station, is furnished on the Panama Railroad to employees, and half rates are given in all other cases, and also half rates to families of employees. Free transportation in some cases, and in all other cases transportation at reduced rates to and from the Isthmus, is provided to employees and their families.
Six weeks' leave of absence each year, with full pay, is given to all monthly employees, and this includes not only office and engineering forces but also the mechanical forces on the monthly basis.
The medical and sanitary department is especially to be commended for its success in exterminating yellow fever and controlling malaria, and for other measures which have made the Isthmus a thoroughly healthful place in which to live.
The cost of the sanitary department, which represents the cost of keeping the Isthmus healthful, amounts to about $2,000,000 per year. This is a large sum, but the work is well done, and any decrease in the efficiency of the sanitary service might readily prove disastrous to the prosecution of the main work.
We believe that in no other great construction work has so much been done for employees in the way of furnishing necessities, comforts, and luxuries of life at the cost of the work as has been done in this case. This is one reason for the high cost of the canal.
Progress and time of completion.
We have examined diagrams and statistics showing the amount of work accomplished by years and by months since the work was taken over by the United States, and showing the amounts of the various classes of work remaining to be done and the estimated rates of progress and times required for completion. It has been impossible for us to check these in detail, but we have compared them with other estimates, and with the work obviously done, and they seem reasonable to us. In the light of this showing, we see no reason why the canal should not be completed, as estimated by the chief engineer, by January 1, 1915; in fact, it seems that a somewhat earlier completion is probable if all goes well, but in view of possible contingencies it is not prudent at this time to count on an earlier date.
Cost of work.
In examining the expenditures thus far made it must be borne in mind that large sums have been paid for steamships, dredges, steam shovels, locomotives, cars, tracks, shops and all the equipment that is necessary to prosecute a work of this magnitude, and also that large sums have been spent for dwellings, offices, buildings of various kinds, for waterworks, sewers, paving and other equipment, and that these expenditures have been made, in large measure, for the whole work, and that corresponding disbursements hereafter will be very much less in proportion than they have been to date.
Colonel Goethals has presented to us an estimate of the quantities of materials and the cost involved in the construction of the canal as now planned, including all disbursements thus far made and the estimated amounts required for completion. These cover the greater width of excavation, the increased size of locks, the extra canal channel required by moving the Pacific locks from La Boca to Miraflores, the improved harbor arrangements at Colon, and all other changes which have been adopted or which are now seriously contemplated. The payments to the New Panama Canal Company are included, and also the payments to the Republic of Panama and the cost of sanitation and zone government, for which items the Board of Consulting Engineers of 1905 stated that it presented no estimates.
The estimates and allowances so made seem ample to us. In some items it would seem that considerable reductions could be made, but, on the other hand, the work is large and novel and unforeseen contingencies must be expected, so that it may be that the aggregate estimate as presented is not too large.
After deducting $15,000,000, representing the estimated receipts from the return of money loaned the Panama Railroad, and from the collection of water rates to cover the cost of municipal improvements made in Panama and Colon, and from miscellaneous sources, this present estimate of the complete cost of the lock canal amounts to $360,000,000.
In making this estimate no reduction has been made for whatever salvage may be realized from the construction plant at the termination of the work, which plant has cost to date about $30,000,000.
The cost of the canal, as estimated in 1905, is frequently stated to be $140,000,000, but this is incorrect, as the minority report expressly excluded sanitation and zone government, and the payments to Panama and the French company had already been made. Adding these amounts, using the present estimates of sanitation and zone government, we have in round numbers the following:
Estimate of the minority of the Board of Consulting
Engineers for the cost of construction, exclusive of
sanitation and zone government------------------------------------------------------- $140,000,000
Payments made to the Panama Canal Company and to
the New Panama Canal Company------------------------------------------------------- 50,000,000
Sanitation and zone government, as now estimated------------------------------------ 27,000,000
The difference between this cost and the total cost as now estimated is therefore $143,000,000. Of this amount nearly one-half can be accounted for by the changes in the canal and appurtenant works to which we have already referred, and the remainder is to be attributed mainly to the higher unit cost of the different items of the work, caused in part by the higher prices for plant, supplies and labor which have prevailed in the United States since the estimate of 1905 was made, and which made it necessary to offer very high wages and special inducements in order to obtain the requisite force in a locality where the reputation for health was not good in the earlier years, in part to the adoption of an eight-hour day for most of the work instead of a ten-hour day, in part to the much greater expenditure for housing and care of employees and for auxiliary works than was anticipated, and in part, in our opinion, to the evident purpose to make the estimates ample and to provide liberally for contingencies.
When the work at Panama is completed, in addition to having the canal, the United States will own the Panama Railroad and the steamship line operated in connection therewith.
TYPE OF CANAL.
In view of the fact that the cost of the lock canal, as now proposed, will largely overrun the estimate of the minority of the Board of Consulting Engineers of 1905, and that the excavation in the Culebra cut is being made somewhat more rapidly than was anticipated, we have considered in a very general way the relative cost and time of construction of a sea-level canal.
Most of the factors which have operated to increase the cost of the lock canal would operate with similar effect to increase the cost of the sea-level canal, and at the present time there are additional factors of even greater importance to be considered as affecting the time of completion and cost of a sea-level canal. One of these is to be found in the Gamboa dam, proposed to be nearly 200 feet in height above its foundations, which would be about 60 feet below the normal river level. Prior to the construction of this dam a long and deep diversion channel must be provided of far greater magnitude than that for the Gatun dam, which has been about two years in progress, and is not yet completed.
Judging by the time required for the construction of dams of similar magnitude in the United States, it is probable that were work on the Camboa dam to be started as soon as possible this one feature of the sea-level project of the Board of Consulting Engineers of 1905 could not be completed until after the time required for the completion of the lock canal. The construction of this dam at Camboa for the control of the Chagres is an essential preliminary to the excavation of the sea-level canal for the 13 miles from Bohio to Bas Obispo.
Furthermore, in addition to the Camboa dam, the sea-level project provides for building for the control of tributary streams three large dams, the sites of which have not been examined.
Work is already far advanced on nearly all parts of the lock canal, and a change in the type would result in abandoning work done which represents large expenditure.
Under the plan now being carried out, the River Chagres and each of the other rivers on the Isthmus tributary thereto is made an ally of the project. The waters of these rivers are handled economically and in such a way as to facilitate the operation of the canal. With the sea-level project, these rivers instead of being allies would be enemies of the canal, and floods in them would greatly interfere with the work.
The excavation of the canal would be carried to 40 feet or more below sea level and to a much greater depth below the bottoms of the valleys in which the upper streams now flow.
It would further be necessary to cut long and large diversion channels on each side of the canal for streams entering the Chagres Valley. The cost of such lateral channels to protect the Culebra cut alone from the comparatively small streams formerly entering it, including work done by the French, has probably been not less than $2,000,000. The channels required for the lower valley of the Chagres would be necessarily much longer, larger and far more expensive.
ROCK EXCAVATION UNDER WATER.
Much has been said about the economy of excavating rock under water by modern appliances as compared with the cost of such excavation in the dry with steam shovels after blasting.
We concur in the opinion of those in charge of work at the Isthmus that it is more economical, where the conditions are favorable, to excavate rock in the dry than by any undder-water process now in use. Experience is not yet available to us which will justify the belief that, with the depth of cut and the quality of rock found on the Isthmus, the general adoption of subaqueous methods would prove more expeditious or cheaper.
It is probable that more economical subaqueous methods will be sometime developed, but it would not be wise to base a change in plan of important work upon prospective results to be obtained by any method not yet thoroughly tried.
It has been suggested that the canal region is liable to earthquake shocks and that a sea-level canal would be less subject to injury by earthquakes than a lock canal.
We have seen, in the city of Panama, the ruins of an old church, said to have been destroyed by fire, containing a long and extremely flat arch of great age, which convinces us that there has been no earthquake shock on the Isthmus during the one hundred and fifty years, more or less, that this structure has been in existence, that would have injured the work proposed.
Dams and locks are structures of great stability and little subject to damage by earthquake shocks. The successful resistance of the dams and reservoirs supplying San Francisco with water, even when those structures were located near the line of fault of the earthquake, gives confidence in the ability of well-designed masonry structures and earth embankments to resist earthquake shocks.
We do not regard such shocks as a source of serious damage to any type of canal at the Isthmus, but if they were so their effect upon the dams, locks and regulating works proposed for the sea-level canal would be much the same as upon similar structures of the lock canal. The Gamboa dam for controlling the floods of the Chagres in connection with the sea-level canal provides for a lake having an area of 29 square miles when full, and if this water were suddenly let loose into the sea-level canal it would seriously injure large portions thereof and wreck ships therein. A similar result would be reached if the other three dams of the sea-level canal retaining lakes, having an aggregate area of 10 square miles, were to be suddenly destroyed.
We believe that the sufficiency of the water supply for a lock canal has never been seriously questioned. It is true that during the dry season the natural flow of the streams would not be sufficient to furnish the water required for numerous lockages. There would even be times when the natural flow would not suffice to make good the loss by evaporation from the surface of the water in Gatun Lake. During the rainy season there is a great excess of water which can be readily stored in Gatun Lake with its area of 163 square miles. It is proposed to fill this lake during the rainy season 2 feet above its normal level, and to draw it as needed during the dry season. It is computed that by drawing it 5 feet below normal level, which draft would leave 40 feet of water through Culebra cut, the supply in a dry year would be sufficient to serve from 30 to 40 lockages up and an equal number of lockages down daily. Each lockage might consist of a single large vessel, or a fleet of smaller vessels capable of being in the lock at one time, as is common at Sault Ste. Marie. For comparison the published record shows that an average of only 12 ships per day passed through the Suez Canal in 1907.
Ultimately, if needed for increased traffic, additional water may be held from wet seasons and made available in dry ones. This may be accomplished either by raising further the high-water level in Gatun Lake or by lowering the low-water level in the lake, this lowering being accompanied, if necessary, by the deepening of the canal, or storage may be provided by an entirely independent reservoir, for which there are excellent sites.
From our examinations in the neighborhood of Gatun dam, we can find no reason to apprehend important loss of water by seepage through the ridges surrounding the lake, while in our judgment the bed of the lake will be practically impervious to water.
The water supply in sight is so much greater than any need that can be reasonably anticipated that the best method of securing more water when the time of need arrives does not require to be considered now.
Your board is satisfied that the dams and locks, the lock gates, and all other engineering structures involved in the lock-canal project are feasible and safe, and that they can be depended upon to perform with certainty their respective functions.
We do not find any occasion for changing the type of canal that has been adopted.
A change to a sea-level plan at the present time would add greatly to the cost and time of construction, without compensating advantages, either in capacity of canal or safety of navigation, and hence would be a public misfortune.
We do find in the detailed designs that have been adopted, or that are under consideration, some matters where other arrangements than those now considered seem worthy of study. As these proposed changes are of a tentative nature and do not in any case affect the main questions herein discussed, they are not taken up in this report.
FREDERICK P. STEARNS.
ARTHUR P. DAVIS.
HENRY A. ALLEN.
JAMES D. SCHUYLER.
JOHN R. FREEMAN.
Theodore Roosevelt, Special Message Online by Gerhard Peters and John T. Woolley, The American Presidency Project https://www.presidency.ucsb.edu/node/206724