Boyds Corners Dam

(Fig. 66).

Rubble 21,000cu. yd., cutstone 6ooocu.yd. Total cost $370,000.

Fig. 66. Section of Boyds Comers dam, New York; built 1867 to 1870; nibble masonry; length 670 ft; max. height 78 ft.; contains 27,000 cu. yd.

San Mateo Dam

(Fig. 67).

This dam was planned for a maximum height of 170 ft. (at which height it would be 680 ft. long), but was stopped at 146 ft. height.

Built of 1-2-6 1/2 concrete deposited in interlocking blocks about 30 ft. X 30 ft. X 10 ft. in size, molded in place.

Rock was hauled in wagons about 1000 ft. from the quarry.

Cement cost in San Francisco $3 to $3.25 per barrel, thence hauled by rail 20 miles to San Mateo, and by wagon 5 miles to the dam. The sand came from North Beach, San Francisco where it was loaded on tram cars, dumped into barges, towed 20 miles up San Francisco Bay to San Mateo landing, thence hauled 8 miles by wagon to the dam. Its cost delivered was $2 per cu. yd. The rock was crushed and the concrete mixed at one end of the dam, the concrete run out in cars on a high trestle, dumped through chutes, then shoveled into wheelbarrows and wheeled to place. The maximum rate of progress was about three of the above-mentioned blocks, or 1000 cu. yd. per day. Estimated cost for the dam to the 170 ft. height $2,000,000.

Matter Dam

Germany; built 1904 to 1012; rubble masonry; length 918 ft; max. height 203 ft.; contains 332,000 cu. yd. masonry; required 222,000 cu. yd. of excavation.

During 1904-05 built a diversion tunnel 29.5 ft. wide X 23 ft. high X1255 ft. long through rock, capacity 10,590 sec. ft.

Upper temporary dam 30 ft. high, 900 ft. above main site, a low dam 460 ft. below main site prevented the water from backing into the pit. Maximum discharge of the river 42,360 sec. ft.; minimum 53 sec. ft.

Stone was quarried in the valley 2 1/2 miles from the dam, brought to the work on hand cars, and hauled by a hoisting engine up an incline to the top of the work. Sand was obtained from the valley directly below the dam. First stone laid June, 1908, completed November 16, 1912.

Spillway was 285 ft. long, 5.9 ft. below crest of dam. At maximum rate of progress laid 1000 cu. yd. per day, and employed 250 masons and 550 laborers.

In connection with the dam, built a power house in which are four 1500-h.p. units. In year of normal rainfall the power is reckoned as 3000 h.p. twenty-four-hour power, at 89 ft. head.

Cost of dam and appurtenances. . . $1,416,000.

Reservoir area 593 acres.

Capacity 1765 million cu. ft.

Watershed area 467 square miles.

Waldeck Dam

(Fig. 68).

Built of rubble composed approximately of 2/3 stone and 1/3 mortar; the mortar consisting of 1 volume of lime, 1 1/2 of trass (volcanic slag) and 2 of sand, a mortar in common use in Germany for hydraulic construction.

The excavation amounted to about 200,000 cubic meters (261,585 cu. yd.) of loose soil and rock. Two hundred masons laid 700 cubic meters (916 cu. yd.) of masonry per day, 200 men cleaned the stones and 300 were engaged in the quarries. The total force was about 900. The drainage area above the dam is 542 square miles, and the reservoir capacity is 202,400,000 cubic meters or 53.5 billion U. S. gallons. The estimated cost of the dam is $1,880,950.

The following is a partial list of recent German dams, their magnitude in cu. yd. of masonry and total cost of the reservoirs. It is taken from a list which appeared in Engineering Record, July 19, 1913, in connection with an article on flood prevention and water conservation measures in Germany.