Niagara Falls 100.000-Hp. Development

Niagara Falls 100,000 H p. Development [7 nel about 200 ft. (60 m.) in width was dug from the company’s inlet outward to the edge of the ice line. Commencing at the intersection of this channel with the ice line, a series of piers were built, running up- stream in the general direction of the ice line but grad- ually working in toward the shore. Floating booms were placed from pier to pier. About half way between this row of piers and the shore another row was placed, extending in the same direction and supporting floating booms in the same manner as the outer row. See Fig. 10. This system has been in operation through one ex- ceptionally severe winter and has proved entirely satis- factory. The booms have kept out the ice floating down FIG. 6—HORIZONTAL CROSS SECTION THROUGH THE TWO TYPES OF DRAFT TUBES EMPLOYED the river, and what small amounts actually formed inside the booms have been broken up from time to time in small quantities by the company’s ice-breaking tugs and allowed to flow down the canal, where they were disposed of through the spillway gates. Prior to this extension the canal was 100 ft. (30 m.) in width and varied in depth at the high-water period of the year from 15 ft. to 22 ft. (4.5 m. to 6.6 m.). In order to get sufficient water through the canal to run the added equipment it was necessary to enlarge the cross section. The canal runs through the most thickly- settled portion of the city, and it was impossible to acquire property rights to widen the canal, so that the only possible thing to do was to deepen it. Drilling, blasting and dredging seemed to be the only practical method, although the proximity of large buildings introduced an element of risk which made extreme cau- tion necessary. The canal is spanned by eight bridges, having a clear- ance above the water surface of from 6 ft. to 15 ft. (1.8 m. to 4.5 m.), which prohibited the use of the ordinary type of dredge, but the long experience of the company’s general superintendent with this class of work had evolved a dredge model that accomplished the work without any undue difficulty. Selection of Wheels The experience of the power company in former de- velopments led to the adoption in 1906 of the horizontal- shaft units for the plant then being designed. How- ever, in 1916, when most of the preliminary engineering on the present extension was undertaken, the Kingsbury FIG. 7—CROSS SECTIONS THROUGH TWO TYPES OF WATER- WHEELS USED SHOW DIFFERENCES IN DRAFT TUBES and General Electric thrust bearings had reached a stage of perfection that eliminated the engineering problem in connection with the supporting of the weight of the rotating parts of the unit. These mechanical difficulties having been eliminated, the efficiency of the unit be- came the deciding factor, and the vertical units were used as offering the best opportunity for the develop- ment of a high efficiency. This type also made possible a vertical discharge and eliminated one 90 deg. bend in the draft tube. Furthei'more the surface elevation of the water in the lower river fluctuates through a vertical range of about 30 ft. (9 m.), so that the vertical design of unit offered the only means of getting the waterwheel run- ner low enough to get the full benefit of the low-water stages and at the same time have the electrical ma- chinery high enough to be safe from damage during high-water stages. The available head obtained by this arrangement varied from 210 ft. to 220 ft. (64 m. to m.), the mean being 215 ft. (QO m-)« Having determined the head, the maximum safe specific speed for the Francis type of runner was at A__Subdivison of expenses for entire extension, including- power plant, transmission and substations. B—Subdivision of investment in buildings. C—Subdivision of investment in hydraulic equipment. D—subdivision of investment in electrical equipment for entire extension. The low engineering expense was due to employing men who were thoroughly familiar with existing conditions and who were thoroughly experienced along lines for which they were responsible. Note that the waterways constituted over 31 per cent of total investment.