REPORT OF BOSTON WATERWORKS

REPORT OF BOSTON WATERWORKS

The Concrete Post Hydrant Box.

The fourteenth annual report of the water commissioner for Boston, for the year ending January 31, 1909, is just at hand. It presents a great array of facts and data concerning the administration of the Boston water department, which deals with the work undertaken and carried on in a way truly meritorious. Some of the leading practices and improvements worked by the department are stated with unusual fullness as to their technical construction. A subject of leading importance, dealt with in detail, is that of repairing and replacing hydrant and gate boxes. The report touching this matter says: “The usual work of repairing and removing gate boxes, frames and covers has been carried on, and while it is well nigh impossible to escape repairing the frames and covers and altering the grade of the boxes, yet we hope, through the substitution of concrete for wood, to avoid the necessity of renewing decayed boxes, the expense of which is quite a factor in our maintenance account. The accompanying cut shows one of the bad breaks repaired by the department. It was a break in a 24-inch high-service pipe, which occurred June 24, 1908. Considerable damage resulted, and, as the report says, as may be seen, the trouble was due to the manner in which a manhole was built under and around our pipe. This was an especially wrong thing to do, but as in many other cases it was done and the inevitable happened. It may be said that good in “peetion, backed up by forceful protest, would prevent such work, but it is sometimes almost impossible, w ith a limited number of inspectors, to thoroughly cover every job progessing in close proximity to our pipes. Unfortunately, corpora lions and some city departments are very often concerned only about the completion of their work, regardless of the manner in which it affects the pipes and fixtures of this department.

INTERIOR VIEW OF CONCRETE BOX SHOP, BOSTON WATERWORKS.CONCRETE BOXES SET UP AS THEY ARE IN THE GROUND, BOSTON.

Referring again to the work of providing hydrant and gate boxes, an innovation in connection with the same in the way of making the boxes of concrete has been carried to success. Pertaining to this matter the report says:

“Previous to the past year, the manufacture of concrete boxes by this department was some what of an experiment, but we now have passed that stage and are rnakin” boxes out of concrete which are satisfactory in every respect and which will last almost indefinitely. The life of a wooden box varied with the soil in which it was set. and with conditions fairly good seven years was a rather long period. It may readily be seen that a concrete box with an almost never-ending life is a much more economical fixture than a wooden box. even though the cost of the former may be slightly more than that of the latter. During the past year boxes for post hydrants, Lowry hydrants, small gate valves and meters were made out of concrete. They are composed of four rothc 154-inch or thin slabs, where the cement faceled or mitered, so that when set up and in union with each other they form a box that is self-supporting. To keep the four sides of the boxes together while backfilling is in progress, the slabs are tied one to the other at the corners with short pieces of wire that are fastened to the reinforcement within. The post hydrant and meter boxes being set in tire sidewalk are only 1¼ inches thick, while the gate-valve and Lowry hydrant boxes are 1¾ inches thick, because of the greater load imposed upon them in the roadway. The proportion of the concrete is approximately 1-2-4. This is modified, however, in the construction of the 1 ’/,-inch or thin slabs where the cement factor is increased somewhat. The reinforcement consists of ¼-mch twisted steel rods which are purchased cut in the desired lengths. They weigh about two-te.nths of a pound to the linear foot. The sand is “Plum Island,” bought by the cargo and delivered upon our wharf. It is clean and sharp and very satisfactory. The stone is finely broken “Roxbury pudding stone,” small enough to pass through a screen of ½-inch mesh and too large to pass through one of ⅛-inch mesh. To thoroughly cleanse it from soil and other foreign matter, it is washed by a 2)4-inch hose stream over a screen of sufficiently large mesh to allow the water to carry off the undesirable material and retain the clean stone. We find that the washed stone increases the strength of the conerete. After being mixed in a “cube” mixer the fresh concrete is placed in w’ooden forms, the inside surfaces of which have been oiled, the reinforcing rods placed in their proper position, and the mass “worked” and compacted by the boxmaker by means of mason’s and plasterer’s trowels until it is well solidified and without voids. The forms are then placed in a rack to set, and in about four days’ time the slabs are taken out of the forms, marked and placed in the storage shed to age, and eventually to serve their purpose in the ground. I’he drawings represented in the cut herewith give an idea as to the dimensions and arrangement of the reinforcement. Although a plan of a post hydrant box, it is typical of the other boxes, with certain modifications as to number of reinforcing rods and dimensions of slabs.

Some data as to the boxes and their construction follow:

Post Hydrant.

Thickness of slabs, 1)4 inches.

Total area of slabs, 48.9 square feet.

Material used:

Portland cement, 127 pounds.

Plum Island sand, 200 pounds.

i inch crushed stone (washed), 400 pounds.

t inch twisted steel rods (.2 pound per foot), 77.6 linear feet.

No 13 galvanized wire. .7 pound.

Lowry Hydrant.

Thickness of slabs. 1)4 inches.

Total area of slabs, 46.1 square feet.

Material used:

Portland cement, 155 pounds.

Plum Island sand, 250 pounds.

inch-crushed stone (washed), 500 pounds.

pinch twisted steel rods (.2 pound per foot), 80.5 linear feet.

No. 13 galvanized wire, .7 pound.

Small Gate Valve.

Thickness of slabs, 14 inches.

Total area of slabs, 35.7 square feet.

Material used:

Portland cement, 125 pounds.

Plum Island sand, 250 pounds.

Rj-inch crushed stone (washed), 500 pounds.

¼-inch twisted steel rods (.2 pound per foot), 67.8 linear feet.

No. J3 galvanized wire, .7 pound.

Meter.

Thickness of slabs, 1)4 inches.

Total area of slabs, 43.8 square feet.

Material used:

Portland cement, 125 pounds.

Plum Island sand, 200 pounds.

4-inch crushed stone (washed), 400 pounds.

4-mch twisted steel rods (.2 pound per foot), 74.5 linear feet.

No. 13 galvanized wire, .7 pound.

Tests to determine the transverse strength of the l-nch Lowry hydrant slab were made as follows:

Post Hydrant Slab. 1⅛ Inches Thick.

The slab was supported with a span of 194 inches at the top and 28 inches at the bottom and was loaded with pig lead on the center line of span. The concrete was sixty days old. The cement used was Atlas. Destruction occurred at 2,600 pounds. The load per linear inch required to destroy the slab was 46.43 pounds.

Lowry Hydrant Slab. 14 Inches Thick.

The slab was supported with a span of 18½ inches at the top and 28½ inches at the bottom and was loaded with pig lead on the center line of span. The concrete was sixty days old. The cement used was Atlas. Partial destruction occurred at 4,007 pounds. It was impracticable to add sufficient weight to cause total destruction. The load per linear inch sustained was 85.26 pounds.

As actual conditions will not test the boxes so severely the results as recorded above assured us of an ample margin of safety.

One of the cuts herewith shows the boxes set up just as they are in the ground, with iron frames and covers placed upon their tops. Each box is numbered and the date of making and the initial or private mark of the workman who made the slab is marked upon the same. The opening in the bottom of the meter box (the small box) is made to allow of the entrance and exit of the service pipe.

Another illustration shows a section of the interior of the shop and the concrete slabs in different stages of construction. Immediately under the cube mixer is a pile of freshly mixed concrete. To the left a workman is seen with trowels in hands about to spread the concrete evenly in the form. L’pon the floor in front of the mixer are two slabs in the forms, both partly made, showing the reinforcing rods and the binding wires. In the rear are some of the racks in which the forms are kept while the concrete is setting.

l he proposition to lease the waterworks of Philadelphia to a private corporation, like Banquo’s ghost, “will not down.” Only recently a wellknown reformer, addressing the Real Estate Exchange on the subject, argued that the trolley and the gas works being run by private corporations there was no reason why the waterworks should not be managed by a private corporation under municipal control.

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