CLEANING A RESERVOIR AT CINCINNATI.
EDEN reservoir, Cincinnati, wis recently subjected to a cleaning process, by which the sediment was removed from the west basin by a process which disclosed an ingenuity of plan and an efficiency of execution superior to the former and usual methods employed in cleaning our reservoirs under former administrations. The east or upper basin was completed in 1872; the west basin was placed In service six years later. The extent of the reservoir is about thirteen acres; its depth is thirty feet; its total capacity, 100,000,00) gallons, divided as follows: East basin, 57,000.000 gallons; west basin, 43,000,000. As this total capacity affords for the winter, when the consumption is at a minimum, but a three days’ supply, two days’ supply during the period of average consumption, and only one and one-half day’s supply in summer time during the maximum demand, there is but little opportunity for subsidence; and the deposit of sediment in the basin, while large, conveys but a faint idea of the suspended matter in the water of the Ohio river.
According to the records and to the memory of Mr. Dennis Murphy, who is one of the “rare very few” who have to any extent of years weathered the many political changes and numerous administrations, the east basin was cleaned in 1S86 and in May, 1894. The west basin was partially cleantd in 1889—the demands for storage capacity requiring a cessation of operations. The lengthy periods between cleanings is due to the lack of reservoir capacity and the absence of a surplus of pumping capacity; and it is only when the pumping plant at the main station at Front street is in good condition, and when the consumption is at the lowest that the cleaning is at all admissible.
In 1886 the east basin, containing sediment to an average of three feet, or au approximate total deposit of 22,000 cubic yards, was cleaned out by shovels and wheelbarrows at a total cost of $11,819, or about fifty-four cents per cubic yard. In 1894 about the same amount of sediment was removed from the same basin by hydraulics at a total cost of $3,133, or about fourteen cents per cubic yard.
The west basin was partially cleaned in 1889; but in the confusion of change of administration no record was made of the cost.
In 1889 the new high-service pumping-station to supply the northern hill-tops was located at the northwest corner of the west basin, extending into the basin, and was afterwards removed for good reasons when the foundation was partially constructed to the east basin; but the dirt was in place to form a new slope round the proposed station. Some large stone in foundation and large forty-eight-inch conduit pipe, with a mass of debris, were not removed, because the demand for storage capacity, caused by a threatened water famine, put the drainage of the basin out of question, and the material, whicb was a tough compacted blue clay, mixed with rock, etc., had to be hauled by ordinary derrick methods at an unavoidably large expense.
At the top portion of the slope,where the fluctuations in the height of the water permitted the action rf the frost, the concrete was found to be in an advanced state of disintegration and large areas of the concrete bottom proved to be in a similar condition—doubtless from inferior workmanship and material in the original construction. At these places the hose streams would tear the concrete out, and, therefore, expensive handling and hands had to be resorted to. The mass of the sediment sliding down the slopes carried with it large quantities of broken rock, which it was necessary to fork out to prevent clogging the sewer. These difficulties encountered enhanced the cost of operations to no little extent.
On October 6, 1896, the entire supply for the city was drawn from the west basin, until the gauge showed nine feet three inches, when the water was turned into the underlying four and five-foot sewers, and, as the mud marked the gauge at seven feet, very little water was wasted. By 11 a. m., on October 9, the water was entirely out, exposing the bottom covered with mud 10 a least depth of about four feet where cleaning had been done in 1889, which was over a small area, to a depth of twelve or fourteen feet at bottom of slopes, with varying depths all over the basin—the average depth being seven feet. At places under the continual pressure far eighteen years, due to a head of thirty feet, stratification had actually taken place.
A pumping plant was located at the north end of the division wall between the basins, and connection was made with the two lines of thirty-inch mains which are used when necessary to supply the high-service pumping station. Two hose lines two and one-half inches in diameter, and cables had been laid before emptying the south flush-valve of sewer by means of a flat-boat which was grounded at that point. The cables were used by the “ pioneer” to draw themselves in a small flat-boat out over the mud to the valve, and with the hose streams they cut a channel to the pump, in which was laid a line of sixinch wrought iron pipe, with connections for hose at suitable intervals, to the middle of the basin, from where another line was laid towards the extreme north and south ends of the basin, with lateral lines where necessary. Two hose streams two and one-half inches in diameter with one-inch nozzle then played continuously on the mud, which was worked to a “ face” and undermined the volume of water, with theaid of men with wooden scrapers carrying the sediment to the flush-valves.
The total cubic yards removed was 84,200, increasing the actual storage capacity 17,000,000 gallons—from 40.000.000 to the nominal capacity of 657 000,000 gallons. The total cost was $0,479, including cost of water used, and the cost per cubic yard was eleven and one-third cents. The excavation at former location of high-service pumping-stacion was done at comparatively small cost, considering the tough character of the material and expensive mode of handling it. The cost of 3,500 cubic yards was$r,497, or forty-three cents percubic yard, leaving the total cost for 80,700 cubic yards moved bv hydraulics $7,982 50, or about ten cents per cubic yard, which latter figure will be the price for cleaning the reservoirs hereafter. By the ordinary methods there is no reason to conclude that the cost per cubic yard would be any less than fifty-four cents —the cost of cleaning the east basin.
The pumping-plant consisted of a Gordon pump and an ordinary boiler of locomotive type. The engine is horizontal, duplex.and non-condensing, with steam cylindereighteen inches in diameter, The pump end is double-acting, with cylinder fourteen and one-half inches in diameter; the stroke is twenty inches.
THE MOUNT AUBURN TANK
illustrated herewith is one of two 60 by 38 feet with a com. bined capacity of 7,000,000 gallons. These tanks were built in 1869 and 1870. Three more have been built since that time. The Mount Auburn tank was erected in answer to a petition of the residents of Mount Auburn and other territory within the corporate limits lying above the elevation of the Eden reservoir A pumping station was built at a minimum elevation below the flowline of Third street reservoir. The twenty-inch main in Broadway was tapped by one of the same diameter, which was extended to the pumping lot and afterwards to the Mount Auburn tank, being reduced to sixteen inches at Montgomery road. Engine and pumps were contracted for. In 1869, the superintendent reported the system complete, and the probable future wants of the system carefully provided for; the machinery, consisting of two horizontal engines, eighteen-inch steam cylinder, nine-inch diameter pumps, fivefoot-stroke; boilers and connections all complete, built by the Niles works in the most substantial manner. The cost was, including ten and two-third miles of main and distribution pipe, $273,884. In 1871, an additional iron tank was built costing $14,715, and three steel boilers were contracted for with Mcllvain & Spiegel at $6,000. In addition to that illu? tration will be found others, representing (1) the plan of clean ing reservoir, as described above by Mr. Tharp; (2) division wall and plant used in cleaning reservoir; (3) cutting first channel for work of cleaning; (4) at work in southwest corner; (5) cleaning at the division wall.
WILLIS P. THARP, C. E.
In bringing to a conclusion a notice of the water works system of Cincinnati, without saying a few words in praise of Mr. Willis P. Tharp. C. E., superintendent and engineer of that system, would be like the play of “Mamet” with the part of Hamlet omitted. It is mainly due to the energy and skill, both scientific and mechanical, of Mr. Tharp that the water works system of Cincinnati is what it is and that it will be in the future what it is intended it shall be. Mr. Tharp is in every respect an up-to-date man, progressive and enl’ghtened in his ideas and methods, always on the lookout for improvements and the first to advocate such as his experience shows will stand the test of time and be suitable to the needs of the city. To add more would be superfluous. Supt. Tharp is too well-known to water works men and readers of FIRF. AND WATER to need further eulogy.