CONSTRUCTION AND MAINTENANCE
Increase In Use of Labor Saving Machines a Feature Advantage of Trenching and Backfilling By Machinery Other Devices That Are Gaining Favor
DURING the past few years a notable change has taken place in the water works field with regard to the manner in which construction and maintenance work is provided. Originally practically all was done by local contractors on competitive bidding, the city furnishing only the more important materials. This has, however, been entirely changed, and instead, the water works plant, even in the smaller city, has its own mechanics and force of laborers who do the work formerly done by contractors. There is a factor which is going to make the water works still more independent and selfcontained, the event of labor saving appliances, such as trenching machines, backfillers, caulking machines. Formerly the chief advantage of securing a contractor to make an extension or repair in a water plant was the force of laborers he had available, a force much greater than a water department could be expected to maintain. But with the new machinery, which removes this advantage, there is little reason for having work done by outsiders; and doing their own work they present a big and permanent market for contractors’ ecpiipment of all sorts, and represent one of the most active fields at this time for such materials.
The feature in construction and maintenance work of water departments during the year will be the increasing use of these labor-saving machines.
As for trenching machines, the experience of Detroit. Mich., is typical of that of the larger cities throughout the country. Because of the difficulty of procuring labor the Detroit Water Department started in 1917 purchasing trench machines, and up to the present time it has bought five, two small, one of medium size, and two large enough to excavate trenches six feet wide for laying 48inch mains. Not only was the number of laborers required greatly reduced, and work speeded up by use of the machines, but the cost of work was appreciably reduced, as shown by the following figures; For 6-inch pipe with hand labor, the cost was 42 cents per lineal foot, and with machine work. .10 cents, a decrease of 12 cents per foot in favor of the machine. On 8-inch pipe, 45 cents with hand labor and .11 cents with a machine, a decrease of 14 cents in favor of the trench machine. On 12-inch pipe the cost by hand was 67 cents and by machine 40 cents, a saving of 27 cents in favor of the trench machine. The trenches were 5 1/2 to 6 feet deep for pipe up to and including 12 inches in diameter. Some of these Detroit machines are illustrated herewith. New York city found that the cost of excavating for pipes totalled 23.4 cents per cubic yard, of which amount 7.2 cents per cubic yard was paid for rental on the trenching machine. Backfilling cost 15 per cent, more than excavation. Trenching machines have found a permanent field in large water works and it will not be long before the smaller plants follow the example set by the bigger cities. Spring will find a lively market for trenches in water plants.
The interesting experience of the New York Department of Water Supply, which found that the cost of backfilling trenches by hand cost fifteen per cent more than the excavating by machine indicates the necessity of using power driven backfillers. It has been estimated that with a certain type of backfiller now on the market, the machine, along with its operator, can accomplish as much as sixteen men with horse-drawn scrapers; the inefficiency of horse-drawn equipment being due in a large extent to the difficulty experienced in getting over the soft ground, and also in the horse becoming entangled in their harness. Backfilling with hand shovels, especiallv in large installations, is entirely out of the question, both from the standpoint of expense and labor supply. In view of the comparatively low cost of gasoline driven backfillers and their simplicity of operation their adoption in water plants, both large and small, can be looked for during the current year.
Another gasoline operated machine which has a big future in water works is the tamping machine, and more particularly the combination tamping, caulking, drilling, etc., machine which is in reality a portable gasoline driven air compressor with necessary tank and a variety of appurtenances. For tamping it has shown itself capable of giving work of a much more satisfactory nature than hand work, while in caulking it is a phenomenal labor saver. The small water works plants which have installed them have found them useful in every stage of water main construction. When the trench is being dug the} are used for drilling holes for blasting boulders encountered ; when the pipe is being laid they are used for calking; after the main has been tested and covered, their ability at tamping is made use of.
Concrete mixers have not, up-to-date, found much of a market in water departments, as practically all work involving the use of concrete in water plants has heretofore been done by contractors, with the exception of minor repair jobs. With the extended-use of concrete in water works as well as sewer and road construction, there is now a movement on foot towards adoption of such machines by cities having more or less of this work to do. Reservoir repairs, culverts, intake repairs, and even concrete pipe are some of the uses to which concrete mixers are put in waterworks.
Night construction work as well as work in covered reservoirs and filter settling basins, is only made possible by an efficient and portable lighting equipment, and one which is complete in itself. Various types of calcium carbide lights have been designed to answer this purpose and their gradually growing use is an indication of their suitability for the work. This is one of the devices that is aiding in making water departments more efficient, and will continue to do so on an increasing scale.
Welding and cutting outfits, particularly of the oxyacetylene type, have been used successfully in almost all industrial lines and it will only be a matter of a short time before they will likewise be adapted to water works purposes. There are so many ways in which welding and cutting apparatus can be employed by the progressive water department that it is surprising they have not found greater use therein up-to-date. For instancy, there is no reason why broken pump cylinders, as well as other members of the pumping engine, and valves, etc., having small ruptures cannot be repaired in the water works repair shop as well as similar machinery in industrial plants. Then, too, the handling of broken sections of heavy pipe is greatly facilitated by cutting into smaller segments with the cutting torch. A cutting and welding equipment should be included in the outfit of every water works repair truck in large plants and should be included in the shop apparatus of the small system as well as the large.