Combined Rock-fill and Earth Dam.
[Fig. 30] shows a section of the Upper Pecos River Dam near Eddy, N. M.
This dam is quite fully described by Mr. Jas. D. Schuyler, in his recent book on “Reservoirs for Irrigation, Water-Power and Domestic Water-Supply,” and need not be mentioned in this paper, further than to call attention to the combination of rock-fill and earth which constitutes its particular type of construction. This type of dam is believed to be for many localities a very good one, but up to the present time has only been adopted for dams of moderate height, under 60 ft.
The San Leandro Dam, California.
A section of the San Leandro Dam, near Oakland, Cal., is shown by [Fig. 31]. This section was supplied by Mr. W. F. Boardman, hydraulic engineer, who superintended the construction of the dam, from his own private notes and data. It differs materially from sections heretofore published, and is 5 ft. higher, thus making it rank as the highest earth dam in the world of which we have an authentic record.
The dam was commenced in 1874, and brought up to a height of 115 ft. above the bed of the creek in 1898. At the present time it is 500 ft. in length on the crest and 28 ft. wide. The original width of the ravine at the base of the dam was 66 ft. The present width of base from toe to toe of slopes is 1,700 ft. The height of embankment above the original surface is 125 ft., with a puddle trench extending 30 ft. below.
FIG. 30.–CROSS-SECTION OF UPPER PECOS RIVER DAM;
COMBINED ROCK FILL AND EARTH.
FIG. 31.–DEVELOPED SECTION OF SAN LEANDRO DAM.