ELECTROLYSIS AT ATTLEBORO, MASS.
Specially written for FIRE AND WATER ENGINEERING.
Out of an estimated total of 3,500 inhabitants there are 13,000 on the lines of pipe at Attleboro, Mass. These consume 202,919,700 gallons of water—a daily average of 554,513 during 1904— giving a per-capita consumption of forty-one gallons daily for each inhabitant and forty-three for each consumer. The system, which is municipal, was installed in 1873, and up to date has cost $472,910.70. The source of supply is a circular well thirty feet in diameter and twenty-five feet deep, situated 150 feet from the bank of the Seven Mill river. The watershed of the river above this well is some eight miles square, and while it may be sufficient for years to come, yet there is so much doubt as to the possibility of its being developed that a greater well area should be provided in the near future, in order that it may be possible at all times to operate the pump at its normal capacity, which is not the case at present. The water commission has had under consideration for two years the advisability of a larger water supply and storage, also, a better fire protection than there is at present. The town abounds in big manufacturing industries, carried on mostly in wooden buildings, and there are several weak points in the waterworks system which should be strengthened. At present the fire pressure is no pounds, which may be held for some time; but, if. as at a recent fire, the force-main bursts, or any accident occurs and the pressure sinks to forty pounds, that is useless as a fire pressure. As it happens, however, two private manufacturing companies have always shown themselves willing to utilise their pumping machinery to keep up the supply so as to afford enough water to throw six good lire streams. The supply has sufficient for fire, but not for domestic uses, especially since the quality of water supplied from these pumps causes more or less alarm, owing to its taste and color being very different from the town’s well supply. The system at Attleboro is pumping into a steel standpipe thirty feet in diameter and 125 feet high. The pumping plant consists of a Deane duplex, compound-engine, with a capacity of 1,500,0011 gallons daily, and a Barr vertical, cross-corn pound of 3,000.000 gallons daily. The capacity of the standpipe is 661,000 gallons; its top is at an elevation of 267.27. or about 142 feet above city level. The distribution system consists of 44.8 miles of cast iron pipe sixteen-inch to one-inch, of which 6,428 feet were laid last year; hydrants, 335; range of domestic pressure fifty-four to sixtv-two pounds; direct pressure for fire, no pounds; meters in service, 1,666, 220 private, as follows: Union rotary, 609 (215 Union rotary); Mersey (thirty-six disk), 162; Nash, 544; Crown, 158; Lambert, fifty-eight; Thomson, forty-three; Empire, thirty-nine; Trident, thirty; Columbia, twenty-one; Ball & Fitts, twenty. Additional storage can be afforded only by a second standpipe of concrete-steel, costing $34,000, 50 feet in diameter and set on a hill outside the city, with intake at elevation 3.50, and with a capacity of 141,687.0 gallons per foot, with a new pipe from the pumping station. The additional supply must come from another well, forty feet in diameter and twenty-five feet deep, to be located about 256 feet from the present well. The combined capacity of the two wells and conduit would then be 300,000 as against the 100,000 of today. The estimated cost of the well and conduit would be $15,000’ of the new connecting twentyfour-inch main and a new twenty-inch main from it would be $36,356.15, and of a future sixteeninch force-main from the pumping station to the standpipe, with all connections and gate-chamber at station, $28,034.47; all these were outside prices; the actual were lower. Electrolysis caused the usual amount of trouble last year—especially in Emory street. A. A. Knudson, electrical engineer of New York city, was employed to report upon the trouble, which was caused by the usual “grounded” return by the railway companies, the rails being neither heavy nor well bonded at the joints, nor reinforced by auxiliary overhead copper conductors. The result of the investigation showed that many of the service pipes were damaged—one group is shown in the accompanying illustration, so bad as to cause their removal on account of leakage. In one street the service pipes in every house burst twice within two years from the effects of electrolysis. The six-inch main in Emory street of which twelve feet were laid bare, is practically destroyed and badly pitted, as will be seen in the accompanying illustration. This main, like others, runs under the tracks of an electric trolley road. Another illustration, also, shows the somewhat rare instance of a meter being seriously affected by electrolysis, but the damage was not due to railway currents. It shows the iron top of a Crown meter, with edges softened—marked x x x in the cut. Of the electric road part of the Bristol County company has been the most destructive as its rails are of heavy sixtv-foot type as against the lighter thirty-foot rails of the Interstate company. This, of course, as Mr. Knudson points out. means twice the number of joints and bonds in a given distance for the Interstate line and a correspondent!)’ higher electrical resistance than the Bristol County’s through a medium of water mains. There are several electric railways entering the town, the most of them fed by the current from the powerhouse in Pawtucket, about eight miles distant; one the Bristol County road, with powerhouses three miles south, and one transformer or substation in the town on West street. Probably more electrical currents will be discovered on another investigation, as the “operation of electric cars in Attleborough, fed from the several powerhouses, causes currents to flow into and through the mains in all sorts of directions. For instance, the currents from one line flow into the mains, pass through them to other streets and pass out of them to the tracks of other lines. This effect is then reversed, sometimes with a frequency of a few seconds of time, and again at intervals of a half hour, depending entirely on the movements of the cars on the different lines.” It is probably rightly conjectured that the building of the County street line in 1900, with its tracks, in spite of a strong protest from the Attleborough board of water commissioners, placed directly over the fourteen-inch main, through the frequent alternating currents, damaged the fourteen-inch force main, which passes through the brook and lies in wet soil for a considerable distance in the street. The railway people, by making use of the grounded return are responsible for the mischief. The Interstate poles have, indeed, one auxiliary track-feeder upon them, but it does not fulfil its intended purpose, and two places were found where the tap connections and the feeder in the poles were broken off. In addition to this inefficient track return on practically all the lines entering and passing through the town, the case is aggravated, as has been shown by the tracks in two of the streets being placed directly over the mains. The appraisement of the loss after the investigation is about as follows: “One hundred and twenty feet total loss, or ten twelve-foot lengths, besides the cost of opening and replacing the street under the tracks in making repairs.” There is probably no doubt that there arc “at least 500 feet more or less damaged, ranging from ten per cent, up to total. The condition of the main as found is such that it is likely to fail at any moment at some point within this 500 feet.” Mr. Knudson concludes his report thus: “Besides the lateral effect of electrolysis upon mains, damage is caused at many of the joints in a piping system, resulting in leaks, which leaks are usually attributed to any other cause except electrolysis. The situation in Attleborough is such that electrolytic action must be going on at many of the joints ; the heavy flow of currents at times found passing through the mains cannot be otherwise than injurious at joints over a large area of the mains. Generally speaking, the electrical conditions in Attleboro, as relating to electrolysis, are such as to suggest that the railway companies have no idea of the damage they are causing to underground mains. This case is similar to a vicious bull roaming at large, which has already gored other people’s property, for which the owners of said bull must be held responsible, and, unless it is promptly and effectually taken in hand, will certainly cause much further damage.’’ It may be added that, under the diligent supervision of Water Commissioner George H. Snell, who is also superintendent of the system, the waterworks plant of Attleboro is kept in the best possible order.