Niagara Falls 100.000-Hp. Development

Niagara Falls 100,000 Hp. Development [17 broad stream, and the main channel is near the Canadian side. Between the main chan- nel and the company’s intakes there is a broad stretch of water intersected with sub- merged reefs and ridges, and having a depth of from 4 to 14 ft. at the mean stage of the water elevation. The engineering problem involved in the river work was to obtain the normal supply of water for the power plants during the winter period of low temperatures and severe ice conditions. The stream never freezes solidly over its entire width, and the outer line of the solid shore ice is located in ap- proximately the same place from year to year. A deep FIG. 22—DRAFT-TUBE FORMWORK FOR I. P. MORRIS UNIT channel about 200 ft. in width was run from the com- pany’s inlet outward to the edge of the ice line. Com- mencing at the intersection of this channel with the ice line, a series of piers consisting of steel sheetpile cylinders filled with concrete were built running up- stream in the general direction of the ice line, but grad- ually working in toward the shore. Floating booms of truss frames 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. This system has been in operation through one ex- ceptionally severe winter and has proved entirely sat- isfactory. The booms have kept out the ice floating down 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 it was disposed of through the spillway gates. 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 FIG. 21—HORIZONTAL SECTION THROUGH TURBINE SETTINGS thickly settled portion of the city, and it was impos- sible to acquire property rights to widen the canal, so that the only possible thing to do was to deepen it. The canal, prior to the enlargement, was 100 ft. in width and varied in depth, at the high water period of the year, from 15 to 22 ft. The new section is of the same width but has been deepened uniformly to 20 ft. Forebay and Penstocks The forebay is 154 ft. 7 in. long,, 75 ft. wide, and 26 ft. 3 in. deep below normal water. It is entirely lined with concrete. Running out of the forébay are three penstocks, which are concrete lined tunnels of 15 ft. 6in. in diameter. The entrance to the penstocks is a bell-mouth 18 ft. 9 in. high by 28 ft. long. The penstock tunnels after leaving the bell-mouths turn downward at an angle of 45 deg. until they reach a plane at EL 353, which is on a line with the center of the waterwheels. They then run as horizontal tunnels out through the rock to the waterwheels in the power house. Of this horizontal part 76 ft. is composed of li-in.-steel plate thoroughly riveted. The space between the steel lining and the rock is filld with concrete. The valve for each unit was placed at the bottom of the penstock close to the turbine in order to save time when fill- ing the penstock after the ordinary shutdown of a waterwheel. Stop gates were provided for the bell-mouth end as an extra precaution. These are merely large steel gates, three for each penstock, the center gate having a small by-pass wicket. These stop gates slide down in steel guides over the face of the bell- mouth. Steel lined grooves were placed in the face of the forebay wall to receive these stop gate guides. Each of the three turbine casings is connected to its penstock through a John- son hydraulically operated, electrically controlled valve. These valves which are the largest in the world, were furnished by the Larner-Johnson Valve and Engi- neering Co. The outer valve housing is