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falls and a power plant below the falls, the amount of power available, and the amount of power that will be required.
The distance to which electrical power can be transmitted.-Messrs. Houston and Kennelly, of Philadelphia, recently made an estimate of the distance to which Niagara water power can be econoznically transmitted by electricity, and in connection therewith stated that “under ordinary conditions the commercial limit of electrical transmission of power from waters of less than 500 kilowatts (670-horse power) can hardly exceed 50 miles," or about three times the distance involved in the case now under consideration. To-day 2,000-horse power are transmitted from the falls at Tivoli, 18 miles, over the Campagna to Rome, where part is used for arc-lighting of streets and the remainder distributed for use in houses.
Electricity generated by machinery actuated by the water power of the falls of the Willamette River is transmitted 13 miles to Portland, Oreg., where it is applied to lighting. Furthermore, July 13, 1893, a committee, composed of Profs. George Forbes and W. C. Roberts-Austen and Col. J. Pennycuick, of the Royal Engineers, reported on the utilization of water power at the Perriya irrigation works in India. This committee, after considering the relative cost of this power and of steain power, reported that there would seem to be every probability that a large portion of the available water power could be profitably used at a distance of 350 miles from the works.
We therefore find that electrical power can readily be transmitted from Great Falls to Washington.
Sites for a power canal and a power plant.—The Maryland side of the river at Great Falls is rocky and precipitous, and the only available place for a canal on this side of the river is occupied by the Chesapeake and Ohio Canal. On the Virginia side the foot of the hills is somewhat retired from the shore of the river, leaving a kind of platean extending from above to below the falls. Through this plateau passed the batteaux canal, constructed in 1785, of the old Potomac Company, of which Gen. Washington was president, and of which portions of the bed and the locks still remain. Our examination of the locality leads to the conclusion that, while the construction of a power canal and a power plant on the Virginia side of the river would not be free from difficulties, it may be accomplished within a reasonable cost.
The amount of power available.-While no series of measurements of the flow of the river in the vicinity ot' Great Falls or profiles of the river in floods at that place aro available, there is a record of the height of the river on the dam immediately above the falls, which record is almost continuous since the completion of the dam in 1886. The flow can not be mathematically connected with the recorded heights, but may be approximately. In 1856, the river being at an unusually low stage, Mr. W. R. Hutton, C. E., assistant engineer to the late Gen. Meigs (then captain), determined by measurement the tlow at a favorable place below Great Falls to be 1,065 cubic feet per second, which measurement was accepted by the Court of Claims in a suit of the Great Falls Manufacturing Company against the United States as the minimum flow of the river at that point. From several years' observations the records of the Washington Aqueduct show that at the lowest stages of the river the water at the gauge above the Great Falls dam is 0.5 foot higher than the crest of the dam.
It is assumed, then, that when the gauge reads 0.5 foot the flow of the river is at the rate of 1,065 cubic feet per second.
Let it be assumed that 75,000,000 gallons per diem will (until another conduit be constructed) be the maximum amount of water that will be required for water supply to the District of Columbia. Seventy five million gallons per diem are equal to 116 cubic feet per second. The amount of water at low water available for power will then be 1,065—116=919 cubic feet per second. If it be assumed that the available fall of the river at Great Falls is 70 feet, the number of horse powers available at the lowest stages is 7,524, and taking 0.85 as the efficiency of turbines, the power of a series of turbines below the falls at the lowest stage of the river would be 6,395horse powers.
The quantity of water flowing over the dam available for power below the dam and also the number of horse powers vary in proportion to the square root of the cube of the height of the water on the dam. Assuming 1,065 cubic feet per second to be the flow corresponding to a river height of 0.5 foot above the dam, the flow corresponding to the recorded heights for the two fiscal years ending June 30, 1892, and June 30, 1893, has been computed and also the corresponding number of horse powers that would have been effective on turbine shafts bolow the falls. The former year may be considered an average year as regards low-water flow; the latter was a year of extraordinary low water. For six days in the year ending June 30, 1893, this horse power would have been 6,395; for seventy-three days in this year anl seventeen days in the previous year it would have been 8,618. The corresponding gross horse powers are 7,524 and 10,175, differing by 2,651. This ditference corresponds to a flow of 375 cubic feet per second. Were this additional flow provided
for during the period of low water, the effective horse power would be increased from 6,395 to 8,648.
Seven and a half miles above Great Falls, and near the mouth of Seneca Creek, a site seems favorable for the construction of a low dam, behind which there could be provided a reservoir area of about 2.5 square miles without overflowing the river banks, and of about 8 miles adjacent lands be submerged. If this greater extent were utilized it would be necessary to raise the banks of the adjacent canal and strengthen the arches of the culverts under it. With every foot in depth of water stored in this reach of the river the low-water flow at Great Falls could be increased to a flow corresponding to 8,618 horse power for about two and two-tenths days, so that it may be possible to provide suffi'ient storage to tide over periods of extreme low water by a dam so low as not to cause the banks above to be submerged, possibly by a movable dam, which, when lowered, would exercise no deleterious intiuence on property above by backwater in times of freshets.
Further study of this subject of storage should be accompanied by surveys and velocity measurements, for which, and other purposes, no funds were at the disposal of the board. Until such study be made it is prudent to consider that only 6,395 horse power would be available at turbine shafts below the falls, and that this amount may possibly be increased by storage to 8,648.
The amount of power required. --It has been found impossible to arrive at an exact determination of this amount. Gas and electricity, sometimes one, sometimes the other, or both, are in actual or contemplated use, but the numbers of gas-burners or of electric lamps, or of electric lamps that should replace burners, and the numbers of hours of service of such lamps are not readily to be determined. Fortunately it has been possible to obtain from Chief Engineer Thom Williamson, U. S. Navy, superintendent of the State, War, and Navy building, the hourly records of the electric service in that building and other data relative to its lighting by both gas and electricity. From these records some idea has been formeil as to the load of an electric plant required for lighting Department buildings, and from other data some guide has been obtained for an estimate of the number of electric lamps required to replace burners in these buildings. Data has also been obtained relative to the lighting of the White House, nearly all the Department buildings, and other public buildings and the public grounds.
The following estimates for street lighting are based upon data obtained from the annual reports of the operations of the engineer department of the District of Coluunbia, and from statistics of May 31, 1894, kindly furnished by Capt. Powell, the Engineer Commissioner of the District of Columbia:
* Recommended by the Commissioners of the District of Columbia.
Where arc lights have been substituted for gas in the District service, 1 arc light has replaced 2.08 gas lamps. But this high ratio would not probably be maintained throughout the District, and in estimating for future needs, the ratio of 2.5 gas lamps to 1 arc lamp bas been used. Under this assumption 3,124 arc lamps are requireil for the present street service, and if the area to be ultimately lighted is taken as double that which is now densely lighted, the conclusion is reached that 6,310 arc lamps will then be required.
The following is a table of the electric lamps now required for public needs:
To determine the horse power required for the above service, which includes all of the public buildings, grounds, and streets of Washington, it is assumed that each 16-candle power incandescent lamp will require 64 watts and each arc lamp 450 watts; that 83 per cent of power at the turbino shafts is effective for incandescent lights and 68 per cent for arc lights, and that four-tenths of the inaximum incandescent load may be required at the same time as the full arc load. Under these assumptions 4,458 horse power should be available at the turbine shafts for generating the electricity required for the lights above tabulated, which is 0.70 of the horse power which may be made available without storage at the lowest river stage. The remaining 30 per cent, or 1,937 horse power, can for the present be used for pumping from the United States mains to the high-service area of the city and for other public purposes.
We find, then, that electrical power can readily be transmitted from Great Falls to Washington; that there can be constructed, at reasonable cost, a power canal around the falls and a power plant below them; that there are available at the lowest stages of the river 6,395 horse power, without storage of water above the falls in the Seneca reach of the river, and 8,618 'horse power with such storage, while 4,458 horse power only are required for the present lighting purposes; and we therefore come to the conclusion that it is entirely feasible to use the water power of the Potomac at Great Falls for the purpose of lighting the public buildings, grounds, and streets of the District of Columbia.
It may be remarked in this connection, that eventually 3,216 additional arc lights will be required for lighting public grounds and streets, calling for 2,853 horse power, and that the lighting of public grounds and streets alone will then require practically all the power available without storage.
Groups (a) and (b) of the table above consist of buildings whose partial or entire lighting is provided for by electric plants operated by individual steam plants already provided. Should none of the water power be applied to their lighting, 2,920 horse power will, for the immediate present, be available for other purposes mentioned above.
But during the past fourteen years the number of street lights in use in the District has doubled. As the increase continues, a time will arrive when the available water power will not suffice for the lighting of all the streets and the public buildinge and grounds. Auxiliary steam power will then be necessary. The most economical application of this power will be, not to the lighting of streets, involving the expense of conduits and mains, but to the lighting of buildings, for in these buildings the steam plants may be located and utilized at the same time for motive power or heating, while the losses of transmission and the cost of conductors will be minimized. In tho end but one-tenth of the water power will be in excess of the needs for street lighting alone, and this would not be an unreasonable reserve.
ADVISABILITY. The question of the advisability of using the power of the Potomac at Great Falls for the public purposes mentioned in Senator Manderson's resolution depends on the present cost of lighting the public buildings and grounds, and the streets of Washington as compared with the probable cost of lighting under the proposed system,
and also on the probable cost of the works required for the latter system and the probable cost of operation.
The cost of lighting under the present system and the probable cost under the proposed system. During the year ending December 31, 1893, the city of Chicago operated 1,110 arc lamps from 4 power stations at an average cost of $96.61 per lanıp per year, using steam power and underground circuits. This cost does not include interest, depreciation, or taxes. The entire cost of land, buildings, plant, dynamos, lamps, posts, conduite, circuits, and all the other items charged to construction December 31, 1893, was $688,312.80.
The mayor and board of public works of Evansville, Ind., reported February 28, 1894, to the common council of that city upon the feasibility of the city owning its own electric plant. This report contains a list in which are to be found 16 cities, besides Washington, using 300 or more are lamps. Thirteen are lighted by private contract at an average yearly cost per lamp of $111.12, St. Louis being furnished 2,000 arc lamps at a charge of $75 per lamp. Three cities own and operate their own plant at an average cost per lamp of $85.62, the cost in the case of Wheeling, one of the three, being $62 per lamp for 400 lamps.
June 20, 1894, contracts for lighting some of the streets of the city of Baltimore with electricity were awarded at $127.75 per arc lamp per year. But two bids were received, one for the eastern district, the other for the western district. The partition of the city was made by the companies bidding, which thus avoided the risk of one underbidding the other and enabled both to secure the maximum price for lighting service fixed by ordinance. One company furnishes 635 lamps, the other 401.
At present the yearly charge to the District for each arc lamp is $182.50.
From these figures it is apparent that this city is paying far above the average charge for arc lights, and about double the cost of such lighting to cities owning and operating their own plant. The figures given are based upon the use of steam plant with its expensive coal consumption.
Estimates which are given herewith have been made of the cost of operating a system actuated by the water power of the falls, and they give $52.33 for the cost per arc light per annum.
It has been assumed that each arc light would replace 2.5 gas burners. The present contract price for each gas lamp per year is $21.50; and at this rate the annual cost for two and a half lamps would be $53.75. The estimated annual cost of an arc light is therefore about the same as the annual cost of the gas burners it would replace.
The advantage in using the water power of the Great Falls for lighting the streets and grounds of the District will be the increased amount of light afforded for the same annual expenditure.
From the foregoing the board concludes that it is advisable to use the water power at Great Falls for the public purposes indicated in the resolution.
GENERAL PLAN OF PLANT.
The general plan of the plant needed may be outlined as follows: Vertical turbines directly coupled to comparatively low-tension alternating-current generators. The potential of the current to be raised by transformers to 10,000 volts and transmitted by an aerial line to the city limits and thence to a convenient distributing station in Washington, by underground cables, and there utilized to actuate polyphase motors. These motors to be mounted on shafts, to which shall be coupled armatures of directcurrent dynamos, each generating unit to be for 100 or 125 lights.
Without surveys it is not practicable to furnish an estimate of the cost of constructing the canal, but an approximate estimate of the cost of all hydraulic and electric plants, buildings, aerial line, conduits, and lamps is $3,764,930. This is for the utilization of that part of the water power of the falls which is deemed available without resort to storage, i. e., 7,524 gross horse power, or 6,395 at the turbine shafts.
This power, even if increased by resort to storage, will not be sufficient to furnish light to private consumers.
Estimate of cost. Hydraulic plant of 12,800 H. P.*
$64, 000 Building for same..
51, 200 Electric plant
109, 710 Aërial line...
102, 150 Distribution plant
250, 000 Building for same
20,000 Cable for mains and lamps.
492, 600 Conduits..
2, 250, 000 Lamps and standards
3, 764, 930
* For the reason that the available hydraulic head is liable to be reduced about one-half in times of freshets the plant estimated for is correspondingly increased. Estimate of cost of operating expenses. Hydraulic plant:
Repairs, 12,800 H. P., at 57 cents.
Attendance and supplies, at $1.44
Repairs, 41 per cent..
Repairs, 14 per cent
Repairs and supplies, 6 per cent....
Repairs, at 10 per cent... Conduits:
Repairs, at 14 per cent.. Lamps and standards:
Repairs at 8 per cent. Administration
Expenses for 6,527 arc lights.
Total expenses per annum for one arc light.......
52. 33 It should be remembered that the above estimates are for a plant capable of utilizing the entire power of the falls without resort to storage, and sufficient for lighting all of the probable future area of the city.
To these estimates should be added the cost of lands, of canal construction, and of annual repairs of canal.
If the plant be limited to the present needs of the city, including the public build. ings and grounds and streets, the estimated cost of plant so limited, and not including the cost of wiring buildings, is $2,441,030, and the estimated annual cost of operating the same is $201.790. As far as can be ascertained from the data furnished the board, the expenditure for the year ending June 30, 1893, for the above lighting was: For gas and oil
$187, 991.31 For electricity from plant not owned by the United States.
77, 198, 24 For electricity from United States plant...
29, 968. 25
295, 157. 80
METHOD BY WHICH THE RIGHT TO USE THE WATER POWER AT GREAT FALLS CAN
BE ACQUIRED, AND WHAT STEPS SHOULD BE TAKEN BY LEGISLATION OR OTHER-
The three riparian owners at Great Falls are the Chesapeake and Ohio Canal Company, the Great Falls Manufacturing Company, and the United States. The lands of the Chesapeake and Ohio Canal Company are mainly cut off from the channel of the river by the interposing lands of the United States, and the proportion of its ownership in the power of the falls must be very limited. The Great Falls Manufacturing Company claims the “. Toulson tract," on the Virginia side of the river, through which a power canal around the falls would have to pass and on which, below the falls, buildings containing hydraulic machinery would have to be constructed. It is also owner of Conns Island, above the falls, which island is the basis of claims still pending against the United States for damages to the water rights of the company. The United States is the owner of several pieces of riparian property at the falls, and although the proportions of the water rights at the falls belonging to the respective riparian owners have never been determined, judicially or otherwise, it appears to be certain that the United States is by far the largest of these owners.
There is now pending in Congress a bill (S. 1359 and H. R. 7280), of which a copy is transmitted herewith, entitled “A bill to amend an act approved July 15, 1882, enti