WE HAD A MIGHTY RIVER: THE ALEXANDER POWER DEVELOPMENT

"The Alexander Power development on the Nipigon River came into service in October 1930."

FROM: THE TWENTY-THIRD ANNUAL REPORT OF THE HYDRO ELECTRIC POWER COMMISSION 1931 page 86-88

"This development is the second constructed on the river by the Commission and, like the first, supplies power to the Thunder Bay System."

"The Nipigon River from Lake Nipigon to Lake Superior has a fall of about 250 feet, varying slightly with the relative stages of water level in the two lakes. Of this head, the Cameron Falls development utilized 75 feet, and the Alexander development 60 feet. About 100 feet of head is still available for development above the Cameron Falls plant."

"The last annual report gave a general description of the scheme of development, and showed views of the main and auxiliary dams taken toward the close of the construction season of 1929.  With the opening of work in the spring of this year, work was pressed on the construction of the main dam, which is a semi-hydraulic earth fill. The heavy rock - filled toe that was built to ensure perfect drainage and to give stability to the dam, had been placed previously, and the foundation prepared before the present season. Material for the earth fill was obtained from borrow pits on the east bank of the river, whence it was taken in dump cars and dumped from trestles along each side of the central pool. Some of the borrow pits were in sand, while others were in pure clay, so that any mix desirable could be obtained by regulating the amount from each of the pits."


"Sluicing was done by two monitors, each placed on a float in the segregation pool. Pressure was supplied by centrifugal pumps, direct connected to electric motors. The pumps were 6 inch by 6 inch two-stage units, equipped with nickel-iron impellers to resist the heavy abrasive action of water carrying a large percentage of silt. The total yardage in the dam is about 800,000 cubic yards, of which 650,000 cubic yards is semi-hydraulic fill, and from the time the season opened in May up to the end of September, there were 580,000 cubic yards placed, the rate being greatest in June, when about 159,000 cubic yards were placed."

"The nature of the river bed up-stream from the dam called for a protecting blanket of clay. This was sluiced in from material on either side of the river to a depth ranging from four to six feet and extending upstream about 400 or 500 feet."

" In the interest of economy in the design of the headworks, the superstructures usually considered necessary where low winter temperatures are experienced was omitted. The motors and hoists for operation of the head gates are housed in a structure , about 7 feet high, along the upstream side of the power house. The placing and removal of stop-logs, racks and head gates is done by a locomotive crane operating on a standard gauge track on the headworks deck."

"All openings over the stop-log and rack checks have matched plank covers fitted for quick handling, so that with the concrete curtain walls extending below low headwater level for each intake, the gate checks and racks are well protected. In addition to this, openings are provided, through which the warm air from  the power house has free access to the space below the headworks deck. Provision has also been made for the provision of electric heaters, if found necessary."

"Construction work was practically completed by the end of the third week in September, 1930. Plans were made for the closure of the outlets of the diversion channel to the left of the power house, through which all the water of the Nipigon River passed during construction of the dam. For several days before the closure, the headpond levels at Cameron Falls station were regulated to meet the period of shut-down without wasting into the Alexander reach, and to allow ample time to draw down the Alexander headwater pool to permit the steel gates to be placed in the diversion sluiceways."

'When the time came for making the closure, the gates were assembled above their respective openings, and suspended on "A" frames in readiness for lowering into the checks. On Sunday, September 28, at 4 a.m., the Cameron Falls plant was closed down and the flow in the river completely stopped, the forebay at the Cameron Falls plant receiving and holding the whole flow of the river coming down from Lake Nipigon. By 7 a.m. , the water in the Alexander reach had fallen so low that only a shallow stream was passing through the two sluices. The gates were dropped into place and sealed. At 10:25 a.m., the entire closure had been completed and by 10:45 the Cameron Falls plant was again carrying load. Early the following morning, the forebay at Alexander had been filled to operating level, and water began to flow over the spillwall, and by evening the depth of flow over the spillwall  was three feet. Under the full head, all structures proved to be entirely water-tight. The first unit was turned over on October 1, and commercial load was first carried on October 21."