Evening Republican, Volume 20, Number 83, Rensselaer, Jasper County, 6 April 1916 — KEEP PANAMA CANAL OPEN BY DREDGING ONLY [ARTICLE]

KEEP PANAMA CANAL OPEN BY DREDGING ONLY

Scientists Prove by Experiments That Numerous Suggestions Offered Are Useless. GEOLOGIST IS VINDICATED Found That Drainage and Wells Would Do No Good —Believed This May Be Last Time Great Waterway Will Be Closed. Ancon (Canal Zone), Panama.—That the rocks in which all the present sliding in the Panama canal is taking place cannot be weakened to any notable degree by heavy rains, and other facts instructive for the civil engineering profession, are results that have been derived from investigations made to ascertain what value, if any, there was in the innumerable suggestions for controlling the canal slides that have been mailed to General Goethals from all parts of the world. ’ That there was nothing practical in all the schemes that contemplated draining the area that has been giving trouble, by means of tunnels or wells, as has been suggested from many quarters, has been conclusively proved by a series of experiments made under conditions that will make the results convincing and of interest to all civil engineers and geologists. Advised That It Was Water.

“It is the water in those slides that makes them slide,” General Goethals has been advised in all languages. ‘ If you had drained off that water by means of small tunnels and wells these slides would not have occurred,” and “by means of wells and tunnels future slides from this rock will be avoided” are two other opinions that have been insistently sent to him for a long time, and especially of late. What General Goethals thought he did not say, but a cable was sent for everything that was needed To conduct a series of investigations that would be the last and convincing scientific answer to all these suggestions. Donald F. MacDonald, the qanal geologist for the last five or six years, was retained and ordered to conduct the most exhaustive experiments along the lines

of the latest geologic knowledge and the suggestions of the commission of scientists that lately came to the canal. Prof. J. K. Mead, a geologist from the University of Wisconsin, who has made a specialty of just such experiments as were suggested, was engaged to come to the canal and assist Mr. MacDonald with his very special knowledge of his latest development of geological work. What Experiments Prove. The experiments Messrs. MacDonald and Mead have been making prove that the rocks that have been sliding contain about 30 per cent, by volume, of water, a very large amount. The rocks that are moving toward the channel of the canal are so broken up that they have had every opportunity to drain and to- lose their water by evaporation. Notwithstanding these conditions, these rocks, as these experiments prove, have only about onehalf of 1 per cent less water than the rocks of the same class that were examined after they had been submerged in the canal for months, a period long enough to have thoroughly saturated them with water.

With this general result as a basis, Messrs. MacDonald and Mead continued their experiments until they proved conclusively that while the rocks that have been sliding contain the high percentage of water mentioned, this water is largely in capillary form and cannot be effectively drained except to the extent of possibly 4 or 5 per cent by any system that could be devised. No more convincing argument can be advanced to prove that not deep drainage of the weak rocks but vigorous digging away by dredges of-the material now sliding, is the remedy for the slides under present conditions. One Theory Absurd. A theory held tenaciously during the dry excavation construction period among the engineers directly connected with the Culebra cut was that the high ground above the canal channel should be allowed to slide so as to reduce the amount of blasting. This was one of the many ideas that General Goethals had to overrule during the building of the canal. These experiments prove that he was absolutely correct from a scientific geological viewpoint in overruling this theory and in digging away with steam shovels as much earth as possible of the banks that might slide. Geologist MacDonald from the first maintained that initial movement, and by this the great weakening of the canal banks should be prevented by terracing the slopes back with steam shovels; for before any movement occurred, slopes might be maintained at an angle of something like one in three, or steeper; but after movement was once started, the sheared rocks could contain enough extra ground water to bring them almost to the consistency of mud. They would, therefore, stand only at a very flat angle, perhaps at one in ten. prove that this is what actually has been happening. They prove that the rock in the canal banks that has given the recent trouble is not weakened or affected to any special degree by heavy rains except after is has moved and thus been weakened. Geologist Vindicated.

In view of these results geologists will be interested to know that Mr. MacDonald’s officially printed reports as long as five years ago emphatically urged upon the division engineer then in charge of the excavation of the Culebra club that these banks that have recently caused trouble by sliding be dug back until the slopes were very much flatter than they were when these recent slides occurred, just where MacDonald predicted they might be expected. The division engineer of the central division, of which the Culebra cut was the principal part, was always absolutely convinced that the slopes considered safe by engineering precedents rather than those the canal geologist recommended and urged would be the ones at which to stop steam shovel excavation. This engineer’s opinion influenced General Goethals, until the time camte, as it did, when the general found that he had to take personal charge of the excavation work in the Culebra cut. When he did this, and, in actual charge, came to see moreTn detail therecommendatlons the geologist had been making, he adopted them as far as* the limits of time and .the advanced condition of the whole work then made possible. Since that time General Goethals has taken genuine inter-

eit in the suggestions experienced geologists have been able to offer after • study of local conditions. This attitude toward practical geologists means much for their future work with civil engineers engaged -in tasks in any way similar to the problems of canal excavation. Work Is Vindicated. The vindication of the work of the canal geologist during the last four or five years made by these experiments has qalled Into notice here the fact that it was the canal dredge division and not Geologist MacDongld that fixed the approximate datq of the last of November, 1915, as the time when a channel say 125 feet wide, would be cleared through the sliding ground. When Mr. MacDonald, in October, made a brief examination of these slides during a stay here qf a flay, he asked the canal engineers when they oould get a narrow channel through the. mass of earth and rock that was then completely barring the canal. They answered, “Two weeks." Whereupon Mr. MacDonald said to a New York World correspondent that if such a channel could be put through by “about the last week in November,” so as to give the dredges and scows a chance properly and effectively to attack the slide, the channel could probably be kept open and gradually enlarged to normal size in spite of the sliding movement, Mr, MacDonald said that there would be some possible chance of the channel closing again during the next four or five months, but when the material now moving had been brought under control by dredging, no new sliding that would close the canal channel would occur, “as long as Gabriel’s trumpet remains unsounded.” The dredging engineers did not have-a narrow channel cleared through the sliding material on the last of November because a dredge broke down, but they had such a channel through about ten days later. The governor of the canal is not permitting vessels, except its own, to go through the channel, because passage interferes with the dredging, and because, as Geologist MacDonald suggested, there is a remote possibility of another closure of the channel should very heavy rains or other unexpected conditions occur, until such time as the dredges remove all the menacing material. After this has been removed, and it is not great in quantity, according to measures on the canal, thouglf it is known that small slides will occur for some years, no slide that will close the canal can occur.