AMERICAN SOCIETY OF CIVIL ENGINEERS. INSTITUTED 1852. PAPERS AND DISCUSSIONS. This Society is not responsible, as a body, for the facts and opinions advanced in any of its publications. AN ALTERNATIVE LINE FOR THE NICARAGUA By Messrs. P. C. HAINS, ALFRED NOBLE, EDWARD P. NORTH, Mr. Hains. P. C. HAINS, M. Am. Soc. C. E.-This project for an alternative route for a Nicaragua Canal comes rather late, inasmuch as the question of route seems to have been settled definitely in favor of Panama. It is understood that the author was employed in Nicaragua by the Maritime Canal Company for a period of about two years, and has given the subject of a Nicaragua Canal a good deal of study. His opinions, therefore, are entitled to consideration. Time will not permit of an extended treatment of this paper, and, under the circumstances, it seems unnecessary, but it is proposed to offer a few comments on certain salient points. The Isthmian Canal Commission, in its report of 1899-1901, submits a project for a canal in Nicaragua substantially on the route suggested by the Nicaragua Canal Commission in 1898. Starting from Brito, on the Pacific coast, the line follows close to that proposed by Colonel Childs in 1850 to Lake Nicaragua. It then crosses Lake Nicaragua and follows the San Juan River, which it is proposed to canalize, to the neighborhood of the junction of the San Carlos * This discussion (of the paper by J. Francis Le Baron, M. Am. Soc. C. E., printed in Proceedings for October, 1902), is printed in Proceedings in order that the views expressed may be brought before all members of the Society for further discussion. Communications on this subject received prior to January 23d, 1903, will be published subsequently. with the San Juan; thence it follows the valley of the San Juan on Mr. Hains. the north side of the stream. The alternative line proposed by Mr. Le Baron refers only to that part of the route lying between the neighborhood of the junction of the San Carlos with the San Juan and the Caribbean Sea, and passes to the sea on the south side of that stream. The author states that: "The importance of good harbors for the termini of the Nicaragua Canal is so great that we could well afford to sacrifice several less favorable features to secure them." This is true, but there are some features which cannot be sacrificed for any reason. A perfectly practicable plan for a canal cannot be sacrificed for one of uncertain practicability; a plan that is free from all experimental constructions should not be sacrificed for one that is not. At the present time there is no harbor at either end of a Nicaragua Canal, and this is true whether the route be that of the Isthmian Canal Commission, or the one proposed by the author. Harbors will have to be constructed at each end of the line. Why, then, should any features of a feasible route be sacrificed to obtain what does not exist? That it is practicable to construct a harbor at the Colorado mouth of the San Juan will not be questioned, but that one exists at the present time cannot be truthfully asserted. Indeed the author seems to admit this fact, for he states that he "considers it" (the mouth of the Colorado) "well adapted for improvement by jetties"; and, also, that there seems to be little reason for doubt that this channel can be deepened to 24 ft. by jetties alone." As a matter of fact, very little is known about the actual conditions at the Colorado mouth of the San Juan River. A survey was made in 1865 by Mr. P. C. F. West, of the United States Coast Survey; and another was made by Commander Tilly, of the United States Navy, in 1898. Neither is really entitled to the name of survey. Only a few soundings were taken on the bar by either West or Tilly, and no tidal measurements were made or other data necessary for formulating a project of improvement obtained. The locality was visited by the Nicaragua Canal Commission in 1898, and again by the Isthmian Canal Commission in 1900. At the time of the latter visit the remains of a wreck were plainly visible off the mouth of the entrance, and the sea, though the weather was normal, was breaking across the entire length of the bar. The "condition of nearly stable equilibrium," which, the author claims, exists there, was not apparent at either time. Still, it will be admitted that the channel might be deepened by the construction of jetties, or by jetties combined with dredging. The author seems to think that the construction of a harbor at or ear Greytown is impracticable. In this he differs from nearly every Mr. Hains. engineer who has studied this question. Many will differ as to the cost of construction. Some may differ as to the causes of the destruction of the old harbor. Some may differ as to the best site available in the immediate vicinity; but none is known to admit that the construction of a harbor is impracticable. The sand movement at Greytown is very similar to that at the Mediterranean end of the Suez Canal, and certainly no one will question the fact that a harbor at the entrance of that canal has been obtained and successfully maintained. "The futility of building a harbor in the re-entrant angle" (near Greytown), the author states, "is exemplified still further by the experience of the Maritime Canal Company"; and that the jetty built by them has been overwhelmed by the sands, and the channel they had cut through the littoral cordon enclosing the harbor lagoon filled up shortly after the work stopped." It is quite true that most of the partially constructed jetty was overwhelmed by the sand, and the channel filled up shortly after the work stopped; but it is remarkable that the engineers composing the Isthmian Canal Commission, as well as others, should draw from the experience of the Maritime Canal Company, in its attempt to form a harbor at Greytown, diametrically opposite conclusions from those formed by the author. This is more particularly strange in view of the fact that the author was employed by that company at about the time the jetty was constructed. The Isthmian Canal Commission states in its report as follows:* "The feasibility, moreover, of constructing a harbor at Grey Town has been practically demonstrated by the work done by the Maritime Canal Company. About 1 000 linear feet of jetty was constructed by that company at a place a short distance west of the location proposed by this Commission, and where the conditions of sand movement are identical. This was quickly followed by the scouring out of a channel on the lee side to a depth of about 7 ft. This channel was made through the sand spit which converted Grey Town Harbor into a lagoon. The channel was increased in depth to 12 or 14 ft. by dredging. No difficulty would have been experienced in deepening this channel still more, and in maintaining the increased depth by the further extension of the jetty seaward aided by dredging and the possible construction of another jetty on the west side." It is to be borne in mind that less than 1 000 ft. of jetty were constructed, and the outer end of it, at the time work was stopped, was nowhere near the 30-ft. contour, beyond which it was expected to go to secure the required depth, but the moving sands were arrested by it and accumulated on the windward side, as was expected. The outflow from the lagoon, without other help, opened a channel for itself, 7 ft. deep, which was increased to about 14 ft. by dredging. That a short piece of unfinished jetty should have produced such results so quickly is believed to establish beyond all doubt, if doubt exist, the practicability of thus opening a harbor. The canal engineers regarded * Report of the Isthmian Canal Commission, 1899-1901, p. 141. it as a practical demonstration of the correctness of the theories on Mr. Hains. which the plans were based. That a further extension of the jetty (which the plans contemplated) would have been followed by a channel of still greater depth is not to be doubted; that in its unfinished condition it should have been overwhelmed by the sands after work stopped, was to be expected. That this sand movement in the near vicinity of Greytown is objectionable, no one will deny; but that it cannot be stopped by groynes or jetties built out from the shore, no engineer familiar with such work would be willing to assert. It is a far easier problem to solve than many others that are encountered on any Isthmian Canal route. It is chiefly one of expense, and not a very serious one, at that. The author is in error when he states that "strange to say, only one location for the harbor has been proposed. If he had read the report of the Isthmian Canal Commission* he would have found that an alternative location for a harbor near the mouth of the Indio, about 6 miles northwest of Greytown, is discussed. Not only was the question of a harbor at that point discussed, but an alternative route for the canal from Lock No. 1 to the harbor site was surveyed. The Commission states as follows: "As already stated, the movement of the sand along the coast, which at Grey Town seems to be at the maximum, decreases as the mouth of the Indio is approached. This stream doubtless brings down some sand and silt during floods. The amount is unknown, but is probably small. Immediately north of its mouth a forest growth, fringing the ocean front, indicates that the shore line is not now being subjected to much change. In view of the small sand movement in the neighborhood of the mouth of the Indio and the apparent stability of the shore line there, it was thought advisable to locate an alternative route from Lock No. 1 to a harbor site at that place.' * "This alternative route is of about the same length as the adopted one to Grey Town, but has a little less curvature. The fore shore of the coast is flatter than in the vicinity of Grey Town, requiring longer jetties to secure a harbor. The jetties should converge seaward to give a large area outside the shore line in which the force of the waves may expend themselves, as at Ymuiden. The first cost of this alterna tive route, both for excavation and harbor jetties, would be greater than that of the adopted one. There is reason to believe, however, that the cost of maintaining the harbor would be less, and possibly the saving in this respect would be sufficient to warrant the greater expenditure for construction." "The data concerning the Indio route are not so well ascertained as those relating to the adopted route terminating at Grey Town, but its advantage in respect to maintenance of the harbor can hardly be doubted. The Commission believes, however, that it is practicable to maintain a harbor at Grey Town which will be fully as serviceable in every way, and regards its advantages as a working harbor as of such importance that its estimates are based on that location." * Report of the Isthmian Canal Commission, 1899-1901, pp. 162 and 163. |