WATER SUPPLY AT MADISON
Improvements in the Pumping System.
It having been found necessary for Madison, Wis., that its supply of water be added to and its pumping system improved, F. E. Tourneaure, of the University of Wisconsin, and Superintendent John B. Heim, of the city’s waterworks department, were appointed to look into and report upon the matter. It was impossible to sink additional wells, as that would only lengthen the suction, with insufficient results, and increase the accumulation of air. The old pumps were inadequate, were in imperfect condition, and were drawing water through a suction of over 4,000 feet, which tended to draw air. with hardly a chance to keep the reserve basin full for fire purposes. The report stated (1) that the maximum capacity of the plant, when operated with the old pumps, was, and is about 1,300,000 gallons per day at a vacuum of about twenty-two inches. (2) The new pump is so placed as to pump the same amount at a vacuum of thirteen inches. (3) If the vacuum could be increased to eighteen or nineteen inches, the yield would certainly be increased to at least 1,800,000 gallons; but, owing to the air in the water, the pump’s action is so interfered with that a vacuum of thirteen or fourteen inches cannot be exceeded. Search was made for leaks in the suction-pipes. These were found. An air-chamber and a vacuum pipe were recommended and were installed. These developed the full capacity of the nine wells as determined by the depth of the suction of the new pump, and no additional water could be expected, without more extensive changes.
To meet the anticipated per capita increase of from fifteen to twenty gallons per day in 1910 and of twenty five gallons in 1920, and to provide for an adequate fire pressure on any day on which the maximum consumption was reached, Prof. Tourneraure and Superintendent Heim recommended either the construction of a 600,000-gallon reservoir to be kept constantly full to meet the requirements of a large fire, or the installation of a deep well pump, such as is manufactured by P. H. Wood, of Los Angeles, Cal. The latter course was adopted. The pump in question lifts the water by two screws —runners—each consisting of two half-circular inclined blades fastened to a shaft at intervals of three to five feet and of slightly less diameter than the casing, so as to revolve free, within the wellcasing (see c., fig. 2), with a boxing for the shaft placed immediately underneath each of the runners; the boxing is held in position by a set of spring blades, termed “guides,” set lengthwise of. and engaging the well-casing, and thereby held firmly in position, and so arranged as to interrupt the whirling motion imparted to the water as it is thrown upwards by the runners, and to turn the water hack in the opposite direction. The water can thus be raised from a depth of several hundred feet hy extending the shaft and runners down the well-casing as far as is needed—care always being taken to keep the lower runner submerged. As the shaft rotates, that runner lifts the water to the runner above it. and so on till the water is delivered above the surface, if desired, according to the size and pitch of the runners, their number, and the speed at which they are run.
The pump proper at Madison is too feet long from base plate, and is inserted in a new eight-inch heavy casing extending 121 feet, from which deptli water can he drawn, and, as the natural depth of the water is about four feet below base plate, the pump is able to lower the water 117 feet, if run at a sufficiently high speed. It was tested with a seventyfive-horsepower motor, with water pumped and power measured. The test, which lasted three hours, showed pumpage at the rate of 1,500,000 gallons a day, gross consumption of fifty-three-horsepower, pump speed 1,360. The water in the well outside of the eight-inch pipe sank seventy-two feet almost immediately and remained steadily at that level. The point of this change was eight feet above the natural level of the water, the lift of the pump being about eighty feet; net work done, about twenty-one-horse-power—a loss of power in motor and belt—transmission of about fifty per cent. The capacity of the wells was 1,200,000 gallons at a vacuum of sixteen inches at the pumping station. In the second test the speed was increased to 1,480 revolutions per minute; yield, at the rate of 1,700,000 gallons a day; gross consumption of power, seventy-two-horsepower. Of course, by using a more powerful motor and a higher speed (one being capable of lowering the water 117 feet) more water could be obtained—hut at greater cost. The test, however, has shown the abundance of the artesian supply. A second pump will be installed in one of the eight-inch wells, with motor, etc., which will add another million gallons to the existing 3,000,000 supply. Each pump will deliver water directly into the low-level reservoir at the pumping station at an estimated cost of $7,150.