EVOLUTIONS OF WATER SUPPLIES.
THE assembling of this American Water Works Convention suggests some reminiscences of the growths and developments of water supply sys tems in America. We, here assembled represent the most useful of them and a large proportion of them. American public water supplies are more than 2,000 in number and they cost more than $600,000,000. Vet some of us remember the inaugurations of very many of them. Let us first refer to a few of those whose early days were beyond our observations.
In the year 1652, the city of Boston had a reservoir near Dock square. This reservoir was 12 feet in length and 12 feet in width. Some wooden pipes led the waterof neighboring springs into this tank which gave the domestic supply of the city. About a half century later four mains of pitch pine logs were laid from Jamaica Pond in Roxbury, into Boston to give an additional supply of water. Two of those pipes were of 4-inch bore and two of 3-inch bore.
In the year 1772. Providence laid two miles of wooden logs and built a reservoir 13.5 feet wide, 30 feet long, and 10 feet deep, for a source of domestic water supply.
In the year 1803 Baltimore laid some wooden and some cast iron pipes. Those iron pipes were an innovation in water supply constructior. They were in 5-foot lengths and of 3-inch bore and they had conical joints. Perhaps these pipes were imported.
In the year 1813, Albany laid three miles of 6-inch cast-iron pipes, for a domestic water supply. It has been claimed that these were the first cast-iron water pipes of American manufacture.
The cities named are among our oldest prominent cities, and their ancient water supplies were among our pioneer constructions.
These were the days when hand lire engines were crude, and before the days of the grand firemen’s tournaments, when improved hand fire engines of one city were matched against those of other cities, and the annual firemen’s parades were the great events of the year.
The improved water supply systems of ouroldercities came later. For instance :
The New ork, Croton works were commenced in 1836 ; the Boston, Cochituate works were commenced in 1848 ; the Albany, gravity supply, was commenced in 1851 ; the Baltimore, Gunpowder supply, was commenced in 1880; the Providence. Pawtuxet supply, was commenced in 1870. The time is really short since the water supplies of a majority of the older cities of the Atlantic slope were essentially domestic supplies only, and such fire supplies as they afforded were by the filling of fire-cisterns located near street corners or in business centres.
The early water supplies of our Eastern townseame usually from springs or small streams.and were led through the streets and to the tanks in the dwellings by small lead pipes, and they were usually the works of private enterprise rather than municipal constructions. Sometimes, two, three, four, or six private aqueduct companies served their customers in the same town and the net work of their small pqres was encountered when the tov/n built improved works with higher pressures.
A fifteenth annuel convention the America Water Work. Aasociatlou held *’ Indianapuiu, 1ml., July 16, a;, ,;
The hand fire engines usually took their water supplies from fire cisterns.
Then came the improved steam fire engine adapted to take suctions from either a fire cistern or a fire hydrant.
As a result, the combined domestic and fire protection systems followed,and fire hydrants on the mains became common. Then came the elevated gravity reservoir systems, with high pressures and hose company fire protections. Then came the practice of pumping the water supplies to high reservoirs, then pumping to tall standpipes, and then, in the level or slightly undulating districts, the direct pumping system with high hose pressures.
All of these high hose pressure systems necessitated greatly increased capacities in the distribution system of pipes and in the water stored to meet fire protection draughts.
In this hasty glance we see a remarkable evolution of methods of water supply construction. Allusion has been made to the evolution to call attention to the effects on the capacities on the distribution mains by the attachment of the fire hydrant to them.
The public water supplies of the last generation, in our States, were, with a few exceptions, insignificant in their constructive proportions ; and they were built chiefly east of the Alleghany mountains.
This generation and we who compose this association have done much of all this most excellent sanitary and fire protection work that now’ covers every city and nearly every village in our vast domain.
The final state of the evolution in construction which has resulted in a combined fire protection and the domestic supply, has wrought a marked change in the financial element of the water supply construction. It has introduced practical elements quite opposite in their requirements.
The domestic supply of the average dwelling may be fully met by a small supply pipe and a very minute jet flowing continuously into a tank in the dwelling—say,a rate of one-third of a gallon per minute; but the fire protection for that dwelling requires constantly the instant readiness of four good hydrant streams, or, say, a rate of flow of too cubic feet, or 750 gallons per minute.
This marked difference in fiow applies not only to the conditions of small towns, but it applies to the residence suburbs and about three-quarters of the area of each large city.
Also, if we apply the same test to the commercial centre of the large city, we find the usual domestic use of water still less for each service pipe, for other than mechanical uses, while the fire protection supply of any warehouse or store must be twelve stronger streams instead of four, or at a rate of at least 2,500 gallons per minute.
These facts indicate the increased capacities of main pipes and the increased costs of main pipes that result in providing the fire protection. This increase is independent of the material increase required to take care of the flush-tank supplies, the street watering trough supplies, and street sprinkling supplies.
This increased cost of capacity for the fire protection is apparent also in the increased cost of pumps, standpipes, reservoirs, and filters, and usually enhances materially the costs and difficulties of procuring the source of water supply.
As the city becomes larger and uses 8,000,000to to,000,000 gallons, or more of water daily, these last costs and the costs of the principal feeder mains become more nearly equalized.
In a middle State city with 75,000 population, the writer found that the excellent filtered domestic water supply which is provided could have been procured from the same source at about one-thi:d the cost of the present combined fire protection and domestic supply. If the domestic supply had been taken from several springs on different high lands near the city, the reductions in lengths and diameters of the main feeders would have lessened still more the relative cost of the domestic supply as compared with the cost of the combined supply.
It may be of interest to the association to learn the estimated relative costs of the different parts of such works as they are last above mentioned, whose total cost for the combined system was about $1,000,000.
The separate items of estimated costs of the domestic alone and of the combined systems will be stated as percentages of the total cost of the combined system, so that they may be readily compared.
Careful estimates in detail of the relative operating expenses in this particular case led to the conclusion that the operating and maintenance expenses of the domestic plant would be about 66 per cent, of the like expenses of the combined plant.
If we assume a similar case where the combined plant, with 80 miles of pipe and 960 fire hydrants, cost $1,000,000, and an equally good and efficient domestic supply could have been provided for $333,333. then we can compare relative annual costs per mile of pipe and per hydrant.
The difference in original capital expenditure is $866,666, which equals $8,333 per mile of pipe.
The difference in annual operating an i maintenance expenses is about $10,ooo. the plant being a high pressure steam pumping plant, wh ch difference equals $125.00 per mile of pipe.
Allowing 6 per cent, interest and 2 1-4 per cent, for a deprcciaion and contingency fund we have for average annual cost per mile of pipe :
This shows for this case an average extra cost of $812 per mile of pipe or $67.70 per hydrant as the annual excess cost of the fire protection.
While the total costs and relative costs of parts of water supplies vary with the aggregate populations supplied vary with the aggregate populations supplied, the areas they cover, and with local conditions, yet such analyses of original costs of parts of the works and of the percentages chargeable to the domestic and to the fire protections are not only interesting as results of the evolutions of water supply systems, but eften suggestive and useful in adjusting rates of revenues, so that the revenues from our admirable and efficient modem fire protections shall be somewhere near commensurate with the proportionate costs pf those fire protections.