Island Falls Power Development on the Churchill River

The article below is the text of a speech prepared by C.R.P. Co. Superintendent Rees Davis and Assistant Superintendent Marvin Huffaker, and presented by Mr. Davis to the annual meeting of the Institute of Mining and Metallurgy held in Winnipeg, Manitoba in March, 1935. This was provided by Joyce Huffaker Hurst.


THE CANADIAN INSTITUTE OF MINING AND METALLURGY--1935

Island Falls Power Development on the
Churchill River

By R.W. DAVIS, and M.F. HUFFAKER

(Annual General Meeting, Winnipeg, Man., March, 1935)  

INTRODUCTION

CHURCHILL river was named for John Churchill, first Duke of Marlborough and third Governor of the Hudson's Bay Company, in the latter part of the 17th century, some fifty years after the ill-fated Danish expedition, led by Munck, had abandoned the site of the now famous seaport of Churchill, as a worthless, cold, disease-ridden country.  

No other attempts were made to explore the interior until the river basin became a part of the grant to the Hudson's Bay Company and began to play its part in furnishing the luxury of-fine furs to civilized people as it had furnished the necessities of food and dress for untold centuries to uncivilized natives. This was the sole contribution of the region to the economic life of the country for some two hundred and fifty years, until 1926, when the power site at Island Falls was discovered by engineers seeking a cheap power source to make possible the development of the great ore-body at Flin Flon.  

DRAINAGE BASIN OF CHURCHILL RIVER

The river is some 1,325 miles long. Rising in the headwaters of the Beaver river, in east-central Alberta, it flows in an easterly direction across Saskatchewan and north-easterly across Manitoba to Hudson bay, through a remarkable basin of some 115,500 square miles, only 6,000 square miles less than the area of the British Isles.  

A journey down this river leads one through three distinct belts of country, each vastly different from the others geologically and in surface characteristics. For the first five hundred miles the river flows through a basin of 36,000 square miles of the great central-plains country, which is covered with fertile soil and carpeted in its southern part with prairie grass, which gradually gives way to the mixed forests of poplar, spruce, birch, and jack pine in the northern and eastern sections. About midway across Saskatchewan, bald-headed knolls and ridges begin to make their appearance as the river meets the western margin of the Canadian Shield. Then, for some seven hundred miles, it passes through country underlain by the pre-Cambrian rocks of the Shield, which continue to within one hundred miles of Hudson bay. Here the character of the country again changes to a low, clay plain underlain by sandstone, and through this 'clay belt' the river flows between steep clay banks, to empty into Hudson bay.

It is with the pre-Cambrian peneplain section that we are mostly concerned, as it comprises 44,000 square miles of the 80,000 square miles of the basin which forms the watershed immediately above the Island Falls plant. The vast ice-sheets of the Glacial period have left evidence throughout this section of their slow but irresistible progress across the country, obliterating the former drainage systems by grinding away old river channels or blocking them with debris. As these ice-sheets slowly retreated, they left in their wake vast lake areas, in which the rock dust was deposited, thus accounting for the clay deposits which are found partially covering the polished surfaces of the pre-Cambrian rock. The water gradually drained from these lake areas as their outlets were uncovered or worn down by stream action, and left a new system of drainage basins, marked by numerous lakes, swamps, and mud flats.  

So recent has this been in the history of the river system that the drainage basin is not yet definitely determined. The whole river system is little more than a series of inter-connected lakes, each lake being connected with the succeeding one by rapids over a low ridge outlet, by a short, rapid river channel, or by a wider, swampy depression through which a lazy current finds its snake-like way (see Figure 1). Climatic conditions will, in time, wear away these outlets, thereby draining the upper lakes and creating a definite drainage system; but on account of the hardness of the rock formation and the fact that the rivers, due to the settling basins formed by the lakes, can carry no abrasive material, this erosion will take many ages. Further evidence pointing to the recent formation of the basin is that, during flood stages, some of the water from the Churchill flows over Frog portage into the Sturgeon Weir river, which is in the Saskatchewan River basin, while Wollaston lake, in the northern portion of the Churchill watershed, even at low level, drains into the McKenzie River system. 

FACTORS GOVERNING FLOW

The climate and geology of this pre-Cambrian portion of the Churchill River basin make this river one of the best, if not actually the best, naturally regulated power stream on the continent. There are many factors contributing to its good behaviour. Perhaps most important is the flat, gradual slope of the forest, lake, and muskeg-covered basin. From Churchill lake to Hudson bay, there is only 1,381 feet drop in a distance of 1,000 miles, 443 feet of this amount, or less than one foot per mile, being above the power plant. About 25 per cent of the pre-Cambrian watershed above Island Falls consists of lake areas, and another 20 per cent is muskeg. These store the water coming into the basin after heavy precipitation or rapid melting of snow, and gradually feed it out to the main river. Another important circumstance is that the river, flowing from west to east, thaws out in the spring at about the same time along its entire length, thus allowing the down-stream water to get away before being overtaken-by water from the upper reaches. Other factors governing the flow are the dense forest and underbrush growth, high evaporation, and the even distribution of precipitation during the year.   The value of this natural regulation has been demonstrated throughout the six years of record during construction and operation of the Island Falls plant, and most particularly in 1934. Large areas of the basin had a very heavy fall of snow during the winter 1933-34 which, on other watersheds, would have caused heavy floods; but it resulted only in a gradual rise in flow at Island Falls from 26,000 to 50,000 c.f.s. in twenty days.  

Most of the conditions which give natural regulation also go to decrease the run-off or output of the river; but since the power demand is small, this is not serious at the present time. Nevertheless, the results are interesting. The large areas of shallow lakes and muskegs aid the cold, dry northern winds in the evaporation of the waters of the basin. As these dry winds move down over the area from higher latitudes, they become warmer and take up moisture from the willing, shallow reservoirs, which, to some extent at least, are restricted only by the density of forest undergrowth.  

A very large percentage of the yearly precipitation is dissipated by evaporation. During the four years, 1931-2-3-4, the total precipitation amounted to 90.18 inches over the 80,000 square miles of the watershed. Of this amount, 97,000,000 acre-feet, or enough to cover lake Winnipeg to a depth of 17½ feet, flowed past the power-house. This is 23.04 inches of the total. During this same period, the water stored in the lakes amounted to 27,000,000 acre-feet, or 6.3 inches. This leaves 60.84 inches dissipated by evaporation, which amounts to 67.2 per cent of the total precipitation during the four years. 

 STORAGE RESERVOIRS

A few large storage reservoirs would accomplish the task of river regulation just as well as the numerous small lakes if, at some time in the future, the river should be called upon to give a maximum of power. There are three such great natural reservoirs in the basin. The largest of these is Reindeer lake, in the north, with an area of 2,300 square miles and a drainage area ten times this amount. Without further investigation, however, we cannot be certain of its total value as a reservoir, as most of the waters of its drainage area are first collected into Wollaston lake, which discharges into both Athabaska and Reindeer lakes. The ratio of the discharges of the two outlets varies with the water level in Wollaston lake, and until we know this ratio, no real dependence could be placed on this pond age in the event of an emergency. The flow from Wollaston lake into the McKenzie basin, however, could be blocked, with the result that, assuming an annual precipitation of 15 inches and 65 per cent evaporation, the average discharge at the outlet of Reindeer lake could be held at 8,000 c.f.s. by varying the water elevation only 4½ feet.  

The next largest reservoir consists of a number of inter-connected lakes, all at the same elevation, and from which the Churchill river proper rises. The largest of these lakes are the Peter Pond, Churchill, Frobisher, and lie a la Crosse. The total area of this multi-lake reservoir is 1,000 square miles, and it draws its water from 29,000 square miles of the Cretaceous central-plain formation of the upper basin of the river. The run-off of this region is more rapid than that of the pre-Cambrian areas; therefore, again assuming an average yearly precipitation of 1.5 inches, but only 50 per cent evaporation, the average discharge at the outlet of Ile à la Crosse could be held at 16,000 c.f.s. by a variation in lake elevation of 18 feet. It will be noted that the drainage area is too large for the reservoir capacity when we consider the flat country in which it is located.  

The third reservoir site, namely that of Lac La Ronge, is situated on the border between the Cretaceous and pre-Cambrian areas. This lake has an area of 500 square miles and drains some 5,700 square miles of country which contains a greater proportionate number of small lakes than either of the two areas above mentioned. Assuming, as before, an average yearly precipitation of 15 inches and increasing the estimated evaporation to 60 percent, the average discharge at the outlet of Lac La Ronge could be held at 2,500 c.f.s. by changing the lake level by 5ft. 8 in.

This indicates that these three large reservoirs, if developed, could regulate the river at approximately 27,300 c.f.s. at the reservoir outlets. 

 HIGH AND LOW FLOW

During the summer of 1930, gauging stations were established at Ile a la Crosse, Lac La Ronge, and Reindeer lake. The readings of these gauges show that, during the four years of record, the level of Ile à la Crosse has gained ten inches, Lac La Ronge forty-five inches, and Reindeer thirty inches (see Figure 2). Up until the year 1928 there were but few data on precipitation; but what little we knew of the river run-off prior to that time indicated a wide variation, coming in periodic cycles of about eight or nine years duration. The data gathered at Island Falls during the past few years seem to verify this conclusion - at least the river flow has varied from a record low of 10,600 c.f.s. in 1929 to an all-time high record of 60,000 c.f.s. in 1932.

    Water marks on the river banks indicate two high flows previous to the record high of 1932. The lower and more distinct one indicates a river flow of 46,000 c.f.s. and, according to natives and meagre data, it occurred in 1908, 1916, and 1924. The high river flow of 1932 established the higher, less distinct high-water mark-which had stood as a maximum for fifty years or more-as representing a flow of 60,000 c.f.s. The river had not risen as high as it did in 1932 within the memory of any Indian native to these parts. The maximum flow of 1934 reached to within 4,000 c.f.s. of this mark.  

The river-flow curves for the last six years furnish some interesting, information (see Figure 3). It seems that the low river flow occurs between April 15th and 30th of each year, while the high flow has no set period. In 1929 it occurred in August, in 1930 during June, in 1931 during October, in 1932 during September, in 1933 during August, and in 1934 during the first part of July. The increase from low flow to the peak of the break-up period has varied also: in 1930, 1931, and 1932 there was a very gradual increase from the season low to the season peak, while during 1933 and 1934 there was a sharp rise to the break-up peak, then a gradual rise a little higher to the season peak.

The late peaks of the first two years of operation were due to the late summer rains of the northern and eastern drainage areas. Present data indicate that it is the amount and distribution of these summer rains, rather than the amount of the melting snow in the spring; that determines the time of the yearly high-water flow. This is, no doubt, due to winter flow draining the lakes down to low levels, leaving large reservoirs to be filled in the spring. It also appears that the water due to snow is stored in muskegs to such an extent that its effect on the river flow at Island Falls is not completely felt until the following year. We need, however, more years of observation to determine with certainty if this is so. The snow of the winter 1933-34, together with the very mild autumn of 1934, has maintained a longer period of high water this winter (1934-35) than would ordinarily have been the case with an earlier, more complete freeze-up.  

CLIMATIC CONDITIONS

Due to the fact that Island Falls is located at north latitude 55° 32' in the interior of Canada and is the most northerly power development of any size in the Dominion, the discussion of climatic conditions is of interest. The writer's experience is now of almost five years' duration and apparently covers the high precipitation period of a high-low cycle, as we have experienced a rise to a peak in 1933 of 26.63 inches and now seem to be on the down slope. The first two years of record during construction of the plant were years of low precipitation; thus it will be interesting to observe the next two or three years, to set: if the traditional length of eight years of the weather cycle is correct. Annual precipitation has been as follows:

  1931 1932 1933 1934
Rain, inches 16.2 13.4 13.81 13.00
Snow, inches  72.9  68.0 128.25  68.5
Total precipitation, inches  23.5 20.2 26.63 19.85

The snow of the cold winters appears like fallen frost particles and lies in loose, fluffy layers until the winds shift it. On the lakes, it drifts like fine sand; in the forests, it settles into a deep blanket of loose, granular particles. The total precipitation is estimated at one-tenth of the snowfall, plus the rainfall.  

Contrary to expectations, the climate is very pleasant throughout the entire year. The long, warm summer days, with 17 hours of sunshine and 5 hours of twilight, go to make outdoor life worth living; and equally long, winter nights provide ample time in the evenings to enjoy friendly wrangles over the bridge table. Although the yearly range of temperature is great - from 52° below to 90° above zero - sudden changes are seldom experienced. Two periods of 50° below weather, each lasting for about a week, have occurred, but since low temperatures here are not ordinarily accompanied by wind, these caused no discomfort. The air is very dry and normally very clear, with an exceptionally high percentage of bright sunshiny days, although the last two winters have been abnormally dull, with lots of cloudy, dreary days, accompanied by fog or low-hanging clouds. Aeroplane flights have been somewhat hampered due to these conditions.  

A great number of lighting storms occur, especially during early summer, but, considering the northern location, sleet storms are few. The 59 miles of transmission line has been struck nine times by lighting, and the northern 20 miles has had one coating of sleet sufficient to cause trouble. The conclusion, in spite of the sand flies, is that this northern climate is truly delightful for both work and play. 

PRELIMINARY SURVEYS

The development of the Island Palls power-site, located in Saskatchewan, 14 miles west of the Manitoba-Saskatchewan boundary, was undertaken and completed by the Churchill River Power Company, Limited, a subsidiary of the Hudson Bay Mining and Smelting Company, Limited; the purpose of the plant being to furnish power for development and mine operation of the large ore-body at Flin Flon, located 59 miles southeast, on the Provincial boundary.  

The Fraser-Brace Engineering Company, Limited, was engaged to make preliminary surveys, plans, and estimates. These were accepted by the Hudson Bay Mining and Smelting Company, Limited, and the Fraser-Brace contract was extended to draw up final plans and furnish engineering during construction, as well as to provide experienced personnel to form a nucleus for a construction staff.  

Preliminary surveys and plans fixing the main features of the power development were completed by the early summer of 1928. These necessitated a study of the meagre river data and the establishment of a river gauging station, in addition to numerous surveys to determine conditions of river channel and bedrock, and the occurrence of local supplies of material such as sand and timber. Transportation to the site then became the main consideration, as about 500 tons of freight had to be moved over lakes and portages to the plant location. The route traversed led from Cranberry Portage across lake Athapapuskow northward to Flin Flon and thence on to Island Falls, a total distance of 110 miles, made up of 90 miles of lakes and 20 miles of portages. The road across the longest of these portages, namely, that from Flin Flon to the south end of Mari lake, a distance of 14 miles, was completed by August 24th; and on this day freight started north, using the 13 wharves at the lake terminals and 9 large barges already built. By October 20th, all the material was landed at the site. The magnitude of this feat can best be comprehended when it is considered that these 1,000,000 pounds of freight had to be man-handled at least twenty times between leaving the cars at Cranberry Portage and arrival at the Island Falls project.  

TEMPORARY PLANT AT SPRUCE FALLS

Power requirements for construction were cheaply solved by the installation of two 1,250 h.p. house units, ultimately intended for use at Island Falls, at Spruce falls, on Swan river, and by transmitting the power a distance of 13½ miles southwest to construction activities. This, therefore, became one of the first jobs to complete, and, with this end in view, the specifications, plans, and orders for the temporary plant were expedited.  

Swan river has a drainage area of 700 square miles consisting of a number of lakes, chief among which are Mari, 19 square miles, Barrier, 55 square miles, and Birch Burntwood, 16 square miles. This system was considered sufficient to deliver ample water to take care of the construction power demand, but later it proved to be inadequate, as will be discussed below.  

Swan river, about four miles in length, is the outlet channel from Birch lake into Sisipuk (Duck) lake, and had an average discharge of less than 220 c.f.s. By utilizing the natural fall of twenty-five feet where the river empties into Duck lake, in addition to a fifteen-foot timber dam of the self-loading type which impounded a small forebay, ahead of forty feet was developed. Immediately above this head water, a timber crib dam was built in order to regulate storage and prevent waste, as it became apparent that water would be scarce.  

The dry season of 1929 resulted in low water level in 1930 and it became necessary to find additional sources of water in order to maintain the amount of power required for construction. The outlet of Barrier lake was cut through, and its 55 square miles of water was lowered six feet in order to furnish enough power to complete the construction at Island Falls. After construction, the outlet was replaced by a faced, rock-filled, timber-crib weir, thus restoring Barrier lake to its former elevation. Because of limited storage, it was only due to the fact that construction was completed so far ahead of schedule that Barrier lake was able to supply sufficient water. In the event of a delay, it would have been necessary to tap other sources in order to obtain an adequate water supply to produce full power from the temporary plant.  

The water from the head pond was delivered to the turbines through two wood stave penstocks, each 90 feet long arid 7 feet in diameter. The two 1,250 h.p. vertical-type turbines, with propeller type runners, were installed, direct connected to 1,000 kVa generators, in a frame building on the shore of Sisipuk lake. The generators delivered power at 600 volts to a bank of outside transformers rated at 2,000 kVa, which stepped the voltage up to 26,400 for transmission to Island Falls.  

The work was started on October 4th and power was delivered on March 28th, 1929. The plant operated successfully, delivering 4,700,000 kWh for construction purposes up to the time No. 1 unit at Island Falls took over the load on June 8th, 1930. The plant was dismantled during 1931 and, under very difficult freighting conditions, due to snow and weak ice, was brought to Island Falls, there to be installed as house units in their permanent places during 1933.  

WORK COMMENCED AT ISLAND FALLS

As winter approached in 1928, two difficult problems faced the engineers in charge of the Island Falls project. Material, construction machinery, and supplies had to be carried 72 miles from the railway, now extended to Flin Flon, to Island Falls, and a construction camp built of sufficient size to receive 23,000 tons of freight and accommodate 500 men. Twelve Linn tractors and 150 heavy freighting sleighs with flat racks were purchased, and a contract let to transport the construction material and equipment. During the winter of 1928-29, 23,000 tons of freight, consisting of provisions, cement, reinforcing steel, steel rails, gasoline, lumber, derrick and trestle timber, contractor's plant, structural steel, and machinery parts which were to be embedded in the sub-structure of the power-house and dam, were carried-in over the ice; and during the following winter, the provisions were replenished, and more steel, cement, and the rest of the power-house machinery were brought in. The total weight of material necessary to complete the plant was 35,000 tons. This enormous amount of freight was handled by trains of six sleighs, drawn by 100 hp Linn tractors, serviced by a caboose for the two crews, who worked in shifts both day and night. Each train brought in a payload averaging about 78 tons, and the maximum recorded load was 124 tons. The average elapsed time for a return trip was 38 hours for the 72 miles.  

Actual work at Island Falls began in September, 1928, and was far enough advanced to deliver some power to Flin Flon twenty-four months later. The first construction was the erection of camp buildings, including an office building large enough to accommodate the offices of superintendent, resident engineer, construction engineer, paymaster, clerk, and cost engineers; staff cottages, a commissary, a kitchen with dining hall, provision warehouse, cold storage, hospital, and bunk-houses; all of sufficient capacity to provide comfortable accommodation for an organization of 800 people. Warehouses, cement sheds, and garages were erected, and stock-yards cleared to care for the construction material as it came in. A carpenter shop, two saw-mills, machine shop, electric supply shop, rock-crushing plant, concrete mixing plant, and boiler-house were erected during the first winter. Local material was used in the construction of all these buildings, with the exception of some of the heavy stringers used in the high trestles of the concrete plant. The buildings of the camp were built of logs on the stockade principle, which gave an attractive appearance to the camp. These structures have proved most serviceable, although not so warm as the horizontal-log type. The lumber used in all building and form work was cut from local trees by two small portable saw-mills, and amounted to 4,000,000 f.b.m.  

This preliminary work occupied the first winter, and the actual construction of the power-plant was not begun until May, 1929, when ground was cleared preparatory to excavation.  

THE POWER PLANT

At the site of the main dam and power-house, the rapids were split into two channels by an island. Water was first diverted from the south channel by means of two rock-filled cofferdams, sheet-piled on the water face, one of which was placed above the scene of operation and the other below. This permitted the excavation for the sub-structure of the power-house and sluice-gate sections of the main dam and also the tail-race, all of which was kept unwatered until the concrete in the sub-structure of this portion of the main dam had set. Following this, the north channel was similarly blocked and the river by-passed through the undersluice gates.  

In order to keep the section between the cofferdams dry during concrete-pouring operations, clay was packed in front of the sheet-piled faces and the of small amount of water that leaked through was pumped out by means of motor-driven, 12-inch centrifugal pumps.  

The power-house sub-structure, containing the intake gates, penstocks, scrollcases, wheelpits, and draft tubes, is an integral part of the main dam and acts as foundation for the cement block masonry of the superstructure.  

The power-house section occupies the south 342 feet of the main dam and provides for the ultimate installation of six units, only the north three being included in the present structure. The south section of the power-house is completed only sufficiently to act as a dam, with penstock openings left for the three future units, bulk-headed by stop-logs in the guides left for the permanent gates.  

The completed portion of the power-house is 200 feet long, 125 feet wide, with a maximum height of 140 feet. It is built to house the first three generators on the main floor, with transformer rooms, operator's gallery, oil-switch rooms, and high-tension bus compartments occupying the portion between it and the gate-house on top of the dam (Figure 4). The elevation of the floor of the generator room is 88 feet, as referred to an established bench mark with assumed elevation of 100 feet, while the transformer room, oil-switch room, bus compartments, and gate-house floor elevations are 99, 130, 153, and 128 feet, respectively.  

To the north of the power-house are three sections of stop-log openings, 15 ft. 6 in. wide, with crest at 115 feet, used as trash spillways. The next section of 90 feet contains four sluice gates with intake opening 12 ft. by 24 ft., the bottom of which is at elevation 55. These gates are of the fixed roller type and are opened by a 40-ton gantry crane and closed by gravity due to their own weight, against a head of 70 feet. Their combined discharge capacity under full head is 40,000 c.f.s. During construction, these sluices served to by-pass the river, as noted above, and now their purpose would be to drain the forebay during an emergency or help to by-pass an unusual flood. Up to the present time, however, no such conditions, necessitating the operation of these gates, have risen.  

The third and last section to the north of the power-house consists of 13 stop-log-controlled spillway sections, each 15 ft. 6 in. wide, with crest at 109. This section has a combined discharge capacity of 45,000 c.f.s.  

At the south end of the power-house, concrete wing bulkhead connects to the south bank of the forebay. This wing dam runs for a distance of 160 feet at right-angles to the power-house, then turns southward through an angle of 36 degrees, and continues for another 337 feet to the edge of the fore-bay. 

 A mile southwest of the main dam is a concrete spillway dam for the purpose of by-passing the surplus flow of the river not necessary for power. The spillway openings are of the same dimensions as at the main dam, except that the sills are at 112 feet elevation. In the 800 feet of dam, there are 46 openings controlled by stop-logs. The combined discharge capacity of this spillway is 90,000 c.f.s., which gives a total discharge capacity for the development of 185,000 c.f.s., or three times the highest river-f1ow on record.  

The main turbines were furnished by the Dominion Engineering Works and are of the I.P. Morris propeller-type design, each rated to produce 16,500 h.p. under a 56-foot head, with the centre line at 66-foot elevation. Each runner consists of six blades formed integrally with a common hub coupled to an 18½ inch vertical shaft. The underneath areas of the blades which are subjected to corrosion are coated with Monel metal, which has proved a perfect job after four and a half years of use.

The square concrete penstocks, of which there are two per unit with an area of 512 square feet, lead from the gates to the scrollcases and are designed to carry the full water capacity of the turbines without excessive velocities.   

The heads of the penstocks are protected from trash at the entrance by screens made of strips of ½ in. by 4 in. iron supported by cross beams.  

The water may be completely shut off from the penstocks and scrollcase by main gates of the fixed roller type. Each gate can be raised by engaging its hoisting clutch with a common line shaft driven by a 15 h.p. induction motor, and is closed by brake-controlled gravity action. Guides are provided ahead of the screens for emergency gates, which are in four sections and are lowered into place by gravity and raised by a 30-ton gantry crane. At their lower end, these penstocks enlarge to form the scrollcase voids in the concrete sub-structure. These concrete water passages have given no trouble, and the walls remain coated with water fungus growth.  

Water is led from the scrollcase through stationary guide vanes, which give it initial direction and also are built strong enough to support the weight of the turbine and generator parts above them.   The water gets its final direction, velocity, and volume from sixteen moveable guide vanes or gates, operated by a system of levers, rings, and oil cylinders, in turn actuated by the governor mechanism as necessity demands. The wheel gets its energy from the pressure on the inclined blades due to the weight and velocity of the water. The relative value of energy derived from each of these factors varies with the opening of the guide vanes-for full gate, about 80 per cent comes from weight and the remainder from velocity. The maximum efficiency of the runner is 92 per cent and is obtained at 85 per cent gate opening.  

The water is carried away from the runner by a draft tube of the Moody type, which consists of a cone-shaped void in the sub-structure, under the runner, with an opening at the bottom forming a passage downstream to the river and a solid frustum of a cone from the centre of its base to within three-eighths of an inch of the hub of the runner. At full load, each runner has a discharge of approximately 3,000 c.f.s., making, with 600 c.f.s. as discharge from the house units, a total of 18,000 for the present installation. It will be seen that this is 400 c.f.s. under the recorded minimum river flow of 1929. The turbines have each run 38,746, 39,032, and 38,396 hours, respectively, or 116,174 turbine-hours, without major repairs being required, although there are slightly pitted areas developing on the upper half of the underneath edge of the runner blades where they make clearance with the throat ring.  

The governors are of the actuator-type, manufactured by the Woodward Governor Company, and regulate the gate openings according to the load requirements. This is accomplished by the variation of system speed changing the normal position of the flyballs, which are driven by an induction motor whose power comes from the unit it governs. As the flyballs change their position, they force a cylindrical pilot oil-valve off from the neutral position, which opens an oil supply to an auxiliary piston. This, in turn, puts the main oil supply cylindrical valve off neutral in the direction necessary to open or close, by servo-motors, the gates as the case requires. This system of valves is provided for the purpose of relieving the flyballs of furnishing the great amount of energy necessary to port a large quantity of oil under pressure.  

Since the moving water column has considerable momentum, the governor is designed to bring the pilot valve back to normal as soon as the gates are moved, in order to avoid overtravel and hunting. This is accomplished by means of a system of levers and bell cranks, which are actuated by the servo-motor piston rod. This arrangement operates a large piston in a dash-pot incorporated in the governor design, whose movement displaces against the action of a helical spring, a smaller piston, which, in turn, through another system of levers, returns the pilot valve piston to its neutral position. Again, as the flyballs return to their normal position, the tension on the dash-pot spring is released and the small plunger regains its original position.  

The governor oil supply comes from an accumulator tank whose oil supply is automatically held between 160 and 180 pounds pressure by a gear pump driven by a 15 h.p. induction motor.  

The generators were designed, built, and installed by the Canadian General Electric Company, Limited. Each main generator is of the vertical type, directly connected to the turbine by means of an 18½-inch shaft 30 feet long. They are rated at 12,000 kVa, 90 per cent power factor, 60-cycle, 6,600 volts, with a speed of 163.6 r.p.m.  

The lubricating system of the generator consists of a system of pumps, sump tanks, and piping to supply oil to the Kingsbury thrust bearing and the upper and lower guide bearings (see Figure S). Oil is pumped from the sump tank in the wheel-pit to a distribution reservoir on the housing of the Kingsbury bearing, from which it overflows, flooding the Kingsbury bearing, thence running by gravity to the other two bearings.

 

From all these bearings, the surplus oil drains back to the sump tank to be re-circulated. This is also supplemented by a gravity system whose oil supply from elevation 130 is regulated by a float valve in the distribution reservoir, which admits oil in case the circulating pump fails.

A float in the sump tank operates a switch at a predetermined high oil level, which, in turn, starts the standby pump, returning oil to elevation 130 until the oil again reaches its normal level in the sump tank. This cycle continues throughout the time the circulating pump is stopped. Sturbinoil B is the type of oil now in use.  

The two house units are rated at 1,000 kVa, 80 per cent power factor, 6o-cycle, 600 volts, at a rotor speed of 400 r. p.m. They are connected to the main system through an auxiliary bank of three transformers each rated at 667 kVa, 600 to 6,600 volts, on the low-tension side of No.3 main transformer bank.  

The exciter system of the main units consists of direct-connected main exciters rated at 100 kW at 250 volts d.c., each of which is regulated by a pilot exciter in whose output a voltage regulator is connected. The house unit exciters are rated at 25 kW at 125 volts d.c. These exciters are supplemented by spare motor-driven exciter which can be used on any unit.  

The generator protection consists of a differential relay system and field failure relay, which will take the unit off the system and hold it down to speed automatically if trouble develops inside the protected area. Each unit operates with its neutral switch closed, an operation made possible since they are not paralleled on the low-tension side.  

The main generators are delta-connected to the low side of individual transformers, which are star-connected high side and paralleled through oil switches onto buses from which the power lines are fed. These transformers are protected by differential or balanced relays, but are not protected from overload, as they are required to handle only the output of one generator. They are rated at 12,000 kVa per bank and are water cooled. Each is installed in a separate compartment on trucks, so that any single tank can be replaced by the spare, kept close by for emergency use.

  The high-tension oil switches, manufactured and furnished by the Canadian Westinghouse Company, Limited, are six in number, one for each unit and line and a sixth which can be used in place of anyone of the others without loss of any of the automatic or protective features.  

In the top of the central section of the power-house and running its full length are two 110 kV buses which are normally used separate, one in service and the other on standby, while a third bus, running parallel to and below these, acts as a transfer for use in conjunction with the spare oil switch.  

Aside from these main divisions of the development, ten earth-filled dams were constructed to hold-in the impounded waters of the forebay. These are scattered along the high-water contour of the flooded section and reach from a point one and a half miles north of the plant to three miles south. The sites of these dams were cleared to solid clay, and a cut-off wall, 2 ft. by 2 ft., was cut on centre line below the high-water elevation of 125 feet. Clean clay was then put in place by teams on the small dams and by means of dump-cars on the large ones, then spread, dampened, and solidly packed. Each dam has a rip-rapped face with a slope of three to one, with benches every five feet on the larger dams, and a smooth clay apron of a two-to-one slope with rock piled at the toe, from which suitable drains are maintained. The crest of all dams is 10 feet wide, and planted with brome grass and timothy.  

THE TRANSMISSION LINE

The greatest undertaking outside the main development at Island Falls was the construction of the 58.9 miles of transmission line from the power-house to the mine at Flin Flon. Material and labour were furnished by Lang and Ross, Limited, under contract. Due to the wild virgin country over which the line was laid out, the first big problem was that of transportation. Once this was overcome, the job resolved itself into the erection of towers, stringing wire, and moving camp, accomplished by fighting black flies and swamps in the summer and snow and cold in the winter.  

The line consists of 356 double-circuit galvanized-steel towers, on which are strung two circuits of three 266,800 cir. mil. steel-core aluminium cables. From the centre of each tower is suspended a 3/8-inch steel ground cable, which runs the entire length of the transmission line. The insulators, designed for 110,000 volts, are made up of l0-inch discs with eight to the string, except at the Flin Flon end where fumes from the smelter have necessitated the addition of extra discs. The power transmission system is shown diagrammatically in Figure 6.

The line has two sectionalizing points, one at Mile 13 and the other at Mile 38, where the two lines may be paralleled or either one sectionalized by means of air-break switches. At each of these points, a line patrolman and his family is stationed. At regular intervals this man patrols the line. At Mile 13, a wood pole, single-circuit, aluminium cable line, forty miles long, taps off either line through air-break switches to feed the Sherritt-Gordon Mines.  

The line operation has been very satisfactory. Outages due to lightning were few during the first three seasons and have been even less frequent during the past two years, especially since a number of the transmission-line towers were counterpoised in the summer of 1932. This counterpoise was installed by running a No.2 stranded cable at least 25 feet out from each tower-leg at a 45-degree angle with the centre line of the transmission line. From one of the legs, the counterpoise line was run to a suitable ground, and, for distances greater than one hundred feet, it was run double. During the early spring of 1933, some bending in the lower braces was experienced on a few of the towers which were embedded in. or on clay. This buckling was caused by the heaving of the clay due to frost and was repaired without very much difficulty, either by straightening or replacement. This, however, has been remedied by trenching under these braces and protecting those most affected with a covering of muskeg, and only in very few instances has the trouble recurred. Some new cases developed last year, however, and we can expect others this year, due to the lack of a protecting cover of snow.

Trouble that may be directly attributed to the cold weather has occurred but twice. At the Mile 38 switchrack, a post-type insulator was broken due to the contraction of a horizontal cable during 40° below-zero weather in the first winter, while a similar condition occurred the following year at Mile 13 during a spell of 50° below-zero weather.  

The construction of the entire project progressed so favourably that No. 1 unit was able to take over the construction at Island Falls on June 8th, 1930; and the transmission line, having successfully passed a high-voltage test two days previously, was placed in service on June 12th, with No.1 unit carrying the Flin Flon construction load of nearly 3,000 kW The rest of the plant was completed and brought into full production in the first half of 1931.  

MISCELLANEOUS WORK AND DEPARTMENTS

The concrete spillway dam was completed and, on August 23rd stop-logs were raised to allow the surplus water to cut a new channel through swamp, muskeg, and clay to Sandy bay, re-entering the old river-channel two miles downstream, and thus forming an island on which is located the townsite. The forebay was filled during July, which completely submerged the three low falls, from which Island Falls gets its name. Two of these falls were on the south, and one on the north side of the large island just above the power-site rapids. The low areas of this island were also covered by the rising waters, thus dividing it into four small islets.  

Contrary to expectations, the filling of the forebay caused very little additional debris to be brought down to the plant from the flooded area. It can be truly said that the river has been remarkably clean, considering the bush territory through which it flows. Only during the summer of 1932 was any difficulty experienced with floating islands of muskeg. The largest of these, a quarter of an acre in area and ten feet thick, driven by a strong wind, lodged against the boom in front of the intake gates and caused considerable anxiety until, by taking out: stop-logs on the spillway section, and with the aid of a number of rope blocks, manpower, and two travelling cranes, it was possible to draw it away and feed it through the openings of the dam. It was covered with bush, some of which was six inches in diameter.  

The prevailing winds are north and northwest across the forebay, thus piling any floating trash against the boom, which extends from the northern end of the power-house to the extreme end of the wing dam. It was found that the waves carried trash over the boom, so, in order to create a still water section in which this trash could be led to the overflow, a second boom was floated into a position parallel to, and twelve feet back of, the first. This arrangement has proved very satisfactory.  

The surplus water is carried over the spillway dam rather than at the plant, for two reasons: first, to keep the resultant spray from condensing on the power-house, lightning arresters, and transmission line; and second, to keep the tail-water low, as it avoids passing the entire river through a restricted channel, which would cause a two-foot rapid with a flow of 20,000 c.f.s., thereby lowering the effective head that much.  

Notwithstanding the severe temperatures of the northern winter, the operation of the stop-logs has been carried out with a minimum of effort, due to improved methods and apparatus used in heating the stop-log guides and hoist spear-heads to keep them free from ice. A whole section of thirteen logs can be put in during the coldest weather in a very short time by two men, after the stop-log hoist has been placed over the spillway and logs. The naturally regulated, steady stream flow makes the necessity for changing logs very infrequent. The major changes come with high water in the spring, and extreme changes of temperature from higher to lower in the early winter, with an occasional change due to load changes at Flin Flon.  

The extremely high water of the past three seasons has cut down our available h.p. output by maintaining a high tail-water level due to restricted channels a few miles below the plant. This condition is being remedied by blasting through debris and dykes blocking two pre-glacial channels and diverting part of the flow from two rapids through them, which action, it is hoped, will increase the available head by five to six feet by the resultant lowering of the tail-race elevation.

There are various departments designed to aid in the operation and maintenance of the inherent parts of the development. Chief among these are the control equipment, the machine shop, the warehouse, commissary, mail and service transportation, and facilities for occupying the leisure time of the employees.  

The control of the entire system is centred in the first operator's gallery, from which the operator keeps in communication with all departments by telephone and knows the condition of all equipment by means of systems of alarms, signals, and indicators. The telephone line, paralleling the transmission line between Island Falls and Flin Flon, maintains a twenty-four-hour service to the central sub-station and the 'central' of the Manitoba Telephone Company, through whom calls can be placed with all outside points, the most distant successful conversation being from Island Falls direct to Toronto. In order to keep in close touch with the patrolmen, the line is tapped and a phone installed in each of the two patrol stations and, in addition, six other call phones are placed at strategic points along the line for the convenience of men on patrol.  

The operator is connected to the camp by two telephone lines, each one mile long, one carrying four phones to various parties, and the other carrying those of the superintendent and the assistant superintendent. The entire telephone system is shown diagrammatically in Figure 7.  

A speaking tube is installed as a means of communication between the control room and the second operator on the generator floor.  

Several Westinghouse switchboards are installed in the operator's gallery, on which are mounted the load indicating meters, relays, remote control switches, and position indicating lamps, the purpose of the last being to give to the operator a constant indication of the exact condition of the various pieces of apparatus.  

Painted on the inclined top of the operator's desk is a six-foot plan of the country between Island Falls and Flin Flon, showing, to scale, the exact location of the transmission line and its relation to the summer and winter transportation routes. Affixed to this panel is a dummy of the power system, showing the connection between each piece of apparatus, from the generators in the power-house at Island Falls to the step-down transformers in the central sub-station at Flin Flon.

This is an arrangement of miniature lights and switches, incorporated with a copper dummy busbar, which shows, at a glance, the exact condition of all switches, disconnects, and transmission line sectionalizing points through the entire system.

The machine shop is an incorporate part of the generator floor and is equipped to handle almost every job appertaining to the maintenance of the entire development.  

Supplies for the entire plant are kept on shelves and in bins in suitable rooms at the power-house, except oil and inflammable stock, which is kept stored in sheds removed some distance from the plant. Supplies and provisions for the employees are stored in warehouses at the camp, which consist of large floor spaces for the storage of non-perishable food stuffs, a heated room for the storage of freezable goods, and an ammonia refrigerating plant which maintains cold storage for our packing-house provisions.  

One year's supply of warehouse stock and provisions is brought in during the winter months and kept stored for use and consumption through the year. It has amounted to upward of 200 tons each operating year in the past.  

A complete ledger account is kept of all items carried in stock, which are checked by an actual physical count, and inventory sheets are made up at the end of each fiscal year. This, together with payroll, correspondence, commissary accounting, etc., occupies the entire time of one accountant.

 CONCLUSION

The Churchill River Power Company, Limited, which is a subsidiary of the Hudson Bay Mining and Smelting Company, Limited, is being operated for the sole purpose of supplying power to the mine at Flin Flon. A study of the load curve will show how well this is being accomplished, for, beginning with a construction load of 2,000 kW in June, 1930, and a production load of 10,000 kW in October, 1930, it has gradually been increased until the peak load of 29,000 kW was reached in December, 1934. Up to the present, a total of 800,000,000 kWh have been generated. This service has been maintained with a minimum of power interruptions - less than one hundredth of one per cent - over the four years of productive operation, during which time only one interruption was charged directly to an error in switching. There have been no disturbances for more than a year from any cause.  

The writers acknowledge with appreciation the wonderful co-operation given by the staff at Island Falls and also that of the Hudson Bay Mining and Smelting Company, Limited, both at Flin Flon and in the general office at Winnipeg, without which this continuity of service would have been impossible.