It is now under construction, and when completed will
impound an area of 1,115 acres.
The dam will be 1,255 ft. long, and formed of Cyclopean rubble set in
cement mortar, and the interstices or spaces between the large masses of
stone, which are rough hewn and not squared, are filled with cement
concrete. The proportion of the cement mortar is 21/2 to 1. These masses of
stone weigh from two to eight tons each, and it is expected that the wall
will be of a most solid description, as great care is being taken to fill
up all spaces. The face next to the water is cemented. The area of the
cross section shown on the diagram, which is at one of the deepest
points, is 8,972 square feet, and the height from foundation to flood
level is 129 ft., the breadth at the base being 117 ft. 9 in.
The existing dam of the New York water supply, Fig. 18, known as the
Croton reservoir, is shown on the diagram. Its capacity is 364,000,000
gallons and the area 279 acres. The height is 78 ft. and width at crest 8
ft. 6 in., and is built of masonry in hydraulic mortar. The face walls
are of stone laid in courses of 14 in. to 26 in., and are vertical on the
up stream side, and with a batter of 1 in 21/2 on the down. The hearting is
of concrete for a depth of 45 ft. from the top, and the remaining depth
is in Cyclopean rubble.
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