Engineering Wonders of the World
Volume III

THE WATER SUPPLY OF NEW YORK CITY. 101 DIAGRAM SHOWING RESERVOIRS SUPPLYING THE NEW CROTON AQUEDUCT. of storage reservoirs on branches and affluents of the Croton River. Early in 1891 the Aqueduct Commissioners resolved to construct across the Croton River, about 1| miles above Quaker Bridge, the already much-discussed, high The New dam. As originally designed, Croton Dam. , . 6 J 6 this was to consist of a central masonry structure, 600 feet long ; an earthen dam, with masonry core-wall of the same length ; and a masonry overflow-weir, 1,000 feet long. In 1896, however, it was decided to extend the central portion 110 feet to the south, and correspondingly reduce the length of the earthen dam. The work was well in hand, and its early completion seemed assured, when, in 1901, Mr. W. R. Hill, the newly- appointed chief engineer, observed in the core- wall some small but, to his mind, ominous cracks. His prompt action following this dis- covery in all probability saved New York from a great catastrophe ; for when the suspected portion of the dam was removed, prior to the substitution of masonry, the foundation was found absolutely unreliable. The changes in the plans now deemed necessary caused such delay in the construction of the dam that it was not until the middle of 1907—nearly fifteen years after ground was first broken— that the work could be pronounced complete. From the photographs reproduced in this article one may gather a gen- Its Huge eraj .jea 0£ architecture Dimensions. . . and imposing appearance ot the finished structure. No pictorial repre- sentation, however, can convey an adequate impression of the dam’s mammoth propor- tions. No one, for instance, unacquainted with the actual dimensions,’ would imagine that th© height from the ground-level to the crest of the dam is 160 feet. The portion of the dam, moreover, seen above-ground constitutes but one-third of the actual mass of masonry in the structure. This extends 137 feet below ground in the centre of the valley, where the thickness of the dam upon the foundations exceeds 200 feet, thence narrowing symmetrically to 18 feet at the crest. The length of the dam from the southern abutment to the bridge is 1,168 feet, and that of the spillway from the bridge to its terminus up the valley 1,000 feet, making a total length of masonry of 2,168 feet. The spillway pro- vides ample security against damage by sudden floods. As the waters flow over it they enter a wide channel blasted in the rocky side of the hill, are then led beneath the steel arch bridge, and finally find their way, by means of an artificial channel, into the old bed of the Croton River. Before the masonry of the New Croton Dam could be built in place, it \vas necessary to excavate 1,750,000 cubic yards of earth and 425,000 cubic yards of rock. The greater part of this material was carried down the valley and dumped into spoil banks, extend- ing in some places many thousands of feet. Although much of the débris was used for restoring the original bed of the valley, there SECTION OF THE NEW CROTON DAM.