Part 7

+--------------+----------+----------------------------------------+ | | | 76 CM. (30 IN.) | | | +-------+------------+--------+----------+ | Employees. | Rate for | Total | Total cost | No. of | Cost per | | | 10-hour | No. | of labor. | pipes | linear | | | day. | men. | Pesos. | laid. | meter. | | | Pesos. | | | | Pesos. | +--------------+----------+-------+------------+--------+----------+ | Foreman | 4.50 | 1 | 4.50 | ... | ... | | Caulkers | 3.00 | 4 | 12.00 | ... | ... | | Lead pourers | 2.00 | 2 | 4.00 | ... | ... | | Lead melter | 1.50 | 1 | 1.50 | 20 | 0.498 | | Pipe cutter | 2.00 | 1 | 2.00 | ... | ... | | Peons | 1.00 | 12 | 12.00 | ... | ... | | Water boy | 0.50 | 1 | 0.50 | ... | ... | | | | | | | | | | ... | 22 | 36.50 | ... | ... | +--------------+----------+-------+------------+--------+----------+ | | | 61 CM. (24 IN.) | | | +-------+------------+--------+----------+ | Employees. | Rate for | Total | Total cost | No. of | Cost per | | | 10-hour | No. | of labor. | pipes | linear | | | day. | men. | Pesos. | laid. | meter. | | | Pesos. | | | | Pesos. | +--------------+----------+-------+------------+--------+----------+ | Foreman | 4.50 | 1 | 4.50 | ... | ... | | Caulkers | 3.00 | 5 | 15.00 | ... | ... | | Lead pourers | 2.00 | 2 | 4.00 | ... | ... | | Lead melter | 1.50 | 1 | 1.50 | 25 | 0.410 | | Pipe cutter | 2.00 | 1 | 2.00 | ... | ... | | Peons | 1.00 | 10 | 10.00 | ... | ... | | Water boy | 0.50 | 1 | 0.50 | ... | ... | | | | | | | | | | ... | 21 | 37.50 | ... | ... | +--------------+----------+-------+------------+--------+----------+ | | | 50 CM. (20 IN.) | | | +-------+------------+--------+----------+ | | Rate for | Total | Total cost | No. of | Cost per | | Employees. | 10-hour | No. | of labor. | pipes | linear | | | day. | men. | Pesos. | laid. | meter. | | | Pesos. | | | | Pesos. | +--------------+----------+-------+------------+--------+----------+ | Foreman | 4.50 | 1 | 4.50 | ... | ... | | Caulkers | 3.00 | 4 | 12.00 | ... | ... | | Lead pourers | 2.00 | 2 | 4.00 | ... | ... | | Lead melter | 1.50 | 1 | 1.50 | 35 | 0.287 | | Pipe cutter | 2.00 | 1 | 2.00 | ... | ... | | Peons | 1.00 | 12 | 12.00 | ... | ... | | Water boy | 0.50 | 1 | 0.50 | ... | ... | | | | | | | | | | | 22 | 36.50 | ... | ... | +--------------+----------+-------+------------+--------+----------+ | | | 45.7 CM. (18 IN.) | | | +-------+------------+--------+----------+ | | Rate for | Total | Total cost | No. of | Cost per | | Employees. | 10-hour | No. | of labor. | pipes | linear | | | day. | men. | Pesos. | laid. | meter. | | | Pesos. | | | | Pesos. | +--------------+----------+-------+------------+--------+----------+ | Foreman | 4.50 | 1 | 4.50 | ... | ... | | Caulkers | 3.00 | 4 | 12.00 | ... | ... | | Lead pourers | 2.00 | 2 | 4.00 | ... | ... | | Lead melter | 1.50 | 1 | 1.50 | 40 | 0.221 | | Pipe cutter | 2.00 | 1 | 2.00 | ... | ... | | Peons | 1.00 | 8 | 8.00 | ... | ... | | Water boy | 0.50 | 1 | 0.50 | ... | ... | | | | | | | | | | | 18 | 32.50 | ... | ... | +--------------+----------+-------+------------+--------+----------+ | | | 38 CM. (15 IN.) | | | +-------+------------+--------+----------+ | | Rate for | Total | Total cost | No. of | Cost per | | Employees. | 10-hour | No. | of labor. | pipes | linear | | | day. | men. | Pesos. | laid. | meter. | | | Pesos. | | | | Pesos. | +--------------+----------+-------+------------+--------+----------+ | Foreman | 4.50 | 1 | 4.50 | ... | ... | | Caulkers | 3.00 | 4 | 12.00 | ... | ... | | Lead pourers | 2.00 | 2 | 4.00 | ... | ... | | Lead melter | 1.50 | 1 | 1.50 | 45 | 0.196 | | Pipe cutter | 2.00 | 1 | 2.00 | ... | ... | | Peons | 1.00 | 8 | 8.00 | ... | ... | | Water boy | 0.50 | 1 | 0.50 | ... | ... | | | | | | | | | | | 18 | 32.50 | ... | ... | +--------------+----------+-------+------------+-------------------+ | | | 30.5 CM. (12 IN.) | | | +-------+------------+--------+----------+ | | Rate for | Total | Total cost | No. of | Cost per | | Employees. | 10-hour | No. | of labor. | pipes | linear | | | day. | men. | Pesos. | laid. | meter. | | | Pesos. | | | | Pesos. | +--------------+----------+-------+------------+--------+----------+ | Foreman | 4.50 | 1 | 4.50 | ... | ... | | Caulkers | 3.00 | 4 | 12.00 | ... | ... | | Lead pourers | 2.00 | 2 | 4.00 | ... | ... | | Lead melter | 1.50 | 1 | 1.50 | 60 | 0.147 | | Pipe cutter | 2.00 | 1 | 2.00 | ... | ... | | Peons | 1.00 | 8 | 8.00 | ... | ... | | Water boy | 0.50 | 1 | 0.50 | ... | ... | | | | | | | | | | | 18 | 32.50 | ... | ... | +--------------+----------+-------+------------+--------+----------+ | | | 15 CM. (6 IN.) | | | +-------+------------+--------+----------+ | Employees. | Rate for | Total | Total cost | No. of | Cost per | | | 10-hour | No. | of labor. | pipes | linear | | | day. | men. | Pesos. | laid. | meter. | | | Pesos. | | | | Pesos. | +--------------+----------+-------+------------+--------+----------+ | Foreman | 4.50 | 1 | 4.50 | ... | ... | | Caulkers | 3.00 | 4 | 12.00 | ... | ... | | Lead pourers | 2.00 | 2 | 4.00 | ... | ... | | Lead melter | 1.50 | 1 | 1.50 | 100 | 0.082 | | Pipe cutter | 2.00 | 1 | 2.00 | ... | ... | | Peons | 1.00 | 6 | 6.00 | ... | ... | | Water boy | 0.50 | 1 | 0.50 | ... | ... | | | | | | | | | | | 16 | 30.50 | ... | ... | +--------------+----------+-------+------------+--------+----------+ | | | 10 CM. (4 IN.) | | | +-------+------------+--------+----------+ | Employees. | Rate for | Total | Total cost | No. of | Cost per | | | 10-hour | No. | of labor. | pipes | linear | | | day. | men. | Pesos. | laid. | meter. | | | Pesos. | | | | Pesos. | +--------------+----------+-------+------------+--------+----------+ | Foreman | 4.50 | 1 | 4.50 | ... | ... | | Caulkers | 3.00 | 4 | 12.00 | ... | ... | | Lead pourers | 2.00 | 2 | 4.00 | ... | ... | | Lead melter | 1.50 | 1 | 1.50 | 150 | 0.0574 | | Pipe cutter | 2.00 | 1 | 2.00 | ... | ... | | Peons | 1.00 | 6 | 6.00 | ... | ... | | Water boy | 0.50 | 1 | 0.50 | ... | ... | | | | | | | | | | | 16 | 30.50 | ... | ... | +--------------+----------+-------+------------+--------+----------+

TABLE 11.--CAST-IRON WATER PIPES.--COST OF MATERIALS AND LAYING AT MONTERREY.

MATERIALS PER STANDARD LENGTH OF PIPE .

Key: cm = centimeter in = inch mm = millimeter kg = kilogram m = linear meter +-----------+------+-------+--------+-------------+--------+--------+-------+ | PIPE | |Weight |Cost/ | LEAD | OAKUM |CHARCOAL| Total | | DIAMETER |Thick-| of |piece +------+------+--------+--------+ Ma- | +------+----+ ness | Pipe |fob Mon-|Weight| Cost | Cost | Cost |terial | | | | | |terrey | | | | | Cost | | cm | in | mm | kg | pesos | kg |pesos | pesos | pesos | per m | +------+----+------+-------+--------+------+------+--------+--------+-------+ | 10 | 4 | 10.3 | 109 | 11.65 | 2.0 | 0.37 | 0.025 | 0.0525 | 3.30 | | 15 | 6 | 11.1 | 163 | 15.74 | 3.7 | 0.67 | 0.0675 | 0.065 | 4.51 | | 30.5 | 12 | 15.8 | 463 | 76.50 | 7.9 | 1.44 | 0.1225 | 0.1 | 21.35 | | 38 | 15 | 17.4 | 680 | 79.36 | 10.6 | 1.94 | 0.175 | 0.12 | 22.30 | | 45.7 | 18 | 19.0 | 871 | 90.28 | 13.4 | 2.42 | 0.2375 | 0.1375 | 25.42 | | 61 | 24 | 22.2 | 1,261 | 117.60 | 18.8 | 3.42 | 0.335 | 0.175 | 33.20 | | 76 | 30 | 25.4 | 1,946 | 199.05 | 24.5 | 4.42 | 0.44 | 0.2125 | 55.77 | +------+----+------+-------+--------+------+------+--------+--------+-------+

LABOR.

Key: cm = centimeter, in = inch, m = meter +-----------+------+------+------+------+-------+-------+---- | | | | | | |Total | | DIAMETER | | | Cubic| Cost |Back- |cost, | | OF PIPE: | Width|Depth |meters| of |filling|exca- | | | of | | per |exca- |and re-|vation | +------+----+trench| |linear|vation|moving |back- | Continues | | | | | meter| per |surplus|filling| | cm | in | m | m | |lin. m|Pesos |etc. | | | | | | | | |Pesos | +------+----+------+------+------+------+-------+-------+---- | 10 | 4 | 0.55 | 0.90 | 0.50 | 0.60 | 0.18 | 0.78 | | 15 | 6 | 0.60 | 1.00 | 0.60 | 0.72 | 0.22 | 0.94 | | 30.5 | 12 | 0.65 | 1.20 | 0.78 | 0.94 | 0.29 | 1.23 | | 38 | 15 | 0.70 | 1.30 | 0.91 | 1.10 | 0.34 | 1.44 | Below | 45.7 | 18 | 0.80 | 1.40 | 1.12 | 1.34 | 0.41 | 1.75 | | 61 | 24 | 1.00 | 1.50 | 1.50 | 1.80 | 0.55 | 2.35 | | 76 | 30 | 1.10 | 1.60 | 1.76 | 2.11 | 0.65 | 2.76 | +------+----+------+------+------+------+-------+-------+----

--+----------------+--------+--------+--------+ | HAULING PER | Cost | Total | Total | | | of |hauling |excava- | | LINEAR METER | laying | and |tion and| | | per |laying |laying, | +--------+-------+ linear | per |labor, | | Haul- | Misc. | meter |linear |complete| | ing | Pesos | | meter | | | Pesos | | Pesos | Pesos | Pesos | --+--------+-------+--------+--------+--------+ | 0.0275 | 0.005 | 0.06 | 0.0925 | 0.8725 | | 0.45 | 0.005 | 0.825 | 0.1325 | 1.0725 | | 0.18 | 0.0075| 0.1475 | 0.335 | 1.565 | | 0.2725 | 0.01 | 0.19 | 0.4775 | 1.9125 | | 0.2725 | 0.01 | 0.245 | 0.5275 | 2.2775 | | 0.825 | 0.08 | 0.41 | 1.315 | 3.665 | | 0.83 | 0.10 | 0.53 | 1.46 | 4.22 | --+--------+-------+--------+--------+--------+

NOTE.--The above costs of earthwork are based on the following rates and percentages over the whole city:

Earth, per cubic meter | 0.35 pesos | 50% Soft sillar | 0.75 " | 20% Hard sillar | 1.50 " | 20% Rock (chiefly conglomerate) | 4.00 " | 10%

SUMMARY OF TABLE 11.

+------------------------+-------------+------------+------------+ | DIAMETER | Total labor | Materials. | Total cost | | OF PIPE : | cost. | Pesos. | per linear | +--------------+---------+ In pesos. | | meter, in | | Centimeters. | Inches. | | | pesos. | +--------------+---------+-------------+------------+------------+ | 10 | 4 | 0.8725 | 3.30 | 4.1725 | | 15 | 6 | 1.0725 | 4.51 | 5.5825 | | 30.5 | 12 | 1.565 | 21.35 | 22.915 | | 38 | 15 | 1.9125 | 22.30 | 24.2125 | | 45.7 | 18 | 2.2775 | 25.42 | 27.6975 | | 61 | 24 | 3.665 | 33.20 | 36.865 | | 76 | 30 | 4.22 | 55.77 | 59.99 | +--------------+---------+-------------+------------+------------+

The flood destroyed about 1,200 houses in the neighborhood of the river. In a number of blocks the smaller mains were scoured away, but considerable salvage was done afterward, and, as it is the intention of the authorities not to permit rebuilding along the flood-path of the river, these mains do not require reconstruction.

MAIN SEWERAGE SYSTEM.

The Company's obligations, as far as drainage is concerned, were limited to the removal and disposal of sewage, no provision being required for storm-water, which is allowed to find its way to the natural watercourses. Apart from that fact, however, the best system for a city like Monterrey, where rainfall for many months at a time is very scarce, is the strictly "separate system." In the design advantage was taken of the natural topography of the drainage district, which is almost an ideal one for a gravitation system of sewers, the general fall in all directions being northeast; it was also in this direction that the best available land could be obtained for disposal purposes.

Plate XX shows in skeleton form the general lay-out of the sewers. Two drainage districts are arranged, divided by Calle de Washington, which may be regarded as practically the center of the city, and each of these districts has an independent main collector connecting to the outfall sewer at the northeast extremity of the city.

The system has been designed so that extensions may be made and may cover any part within the city limits; the main collectors are large enough for the whole area when fully built up.

The sewers are designed on a very liberal basis, namely, on the assumption that when flowing half full the quantity to be dealt with will be 380 liters per capita per day, with a maximum rate of flow of 200 per cent. It was assumed that each house would be occupied by 7 persons and have a frontage of 12-1/2 m. The minimum velocities in the sewers, when running full, vary between 0.91 and 1.5 m. per sec., with the exception of a few blocks.

The minimum size adopted was 24.3 cm. (8 in.) in internal diameter. The sewers of diameters between 24.3 and 50 cm., are 0.91 m. (36 in.) long, and are of salt-glazed vitrified clay, imported from San Antonio, Tex.

Table 12 gives the details of the length of the various sewers laid.

TABLE 12.--LENGTH OF SEWERS.

+----------+------------------------------------------+-----------+ |DIAMETER: | | | +-----+----+ Kind. | Length, | | cm | in.| | in meters.| +-----+----+------------------------------------------+-----------+ |24.3 | 8 | Fire-clay | 38,332.85 | |25.4 | 10 | " | 16,400.69 | |30.5 | 12 | " | 7,953.15 | |38.1 | 15 | " | 4,850.56 | |45.7 | 18 | " | 2,023.40 | |50.8 | 20 | " | 1,450.53 | |55.9 | 22 | Reinforced concrete tubes, 6.9 cm. thick | 3,134.20 | |61.0 | 25 | " " " 7.6 " " | 357.40 | |68.6 | 27 | Brick and concrete | 484.05 | |76.2 | 30 | " " " | 662.69 | | | | | | | | | Total | 75,649.15 | +-----+----+------------------------------------------+-----------+

The greater number of the manholes are of brickwork, 23 cm. thick, and have concrete inverts. They have a diameter of 1.2 m., which is reduced to 0.61 m. at the top, and each is provided with a heavy cast-iron frame and closed cover weighing about 190 kg. There are 521 manholes, and they are placed at every block and on long lines about 80 m. apart.

The sewers are flushed with 15-cm. (6-in.) automatic flushing siphons of the Miller pattern with 20-cm. (8-in.) discharge pipes. There are 278 of these siphons, and they are placed in flush-tanks (Fig. 16) built of brickwork and plastered with 1:1 cement mortar. Their capacity varies from 800 to 1,200 liters, and they discharge from 22-1/2 to 28-1/2 liters per sec. They are timed to flush once in 24 hours.

The system is at present ventilated by 23-cm. (9-in.) steel ventilating columns (Fig. 16), with ornamental cast-iron bases. There are 220 of these columns. Most of them are 7.85 m. above the level of the edge of the sidewalk, and are connected to special 15-cm. branch pipes leading from the sewer on the outside of the flush-tanks. In the center of the city they are provided with extension lengths, giving a total height of 12 m.

Table 13 gives the particulars of the average distributed cost of laying the 75.6 km. of sewers.

TABLE 13.--AVERAGE COST, PER LINEAR METER, FOR 75.6 KM. OF SEWERS, FOR MATERIALS AND LABOR COMPLETE.

+----------+-----------+--------+-----------------------------+--------+ | | INTERNAL |Cost of | EARTHWORK AND LABOR: | Total | | | DIAMETER | mater- |-------+------------+--------| cost of| | | OF | ials | | Cost of |Cost of | sewer | | | SEWERS. |includ- |Average| excavation,|labor |complete| |Kind of +------+----+ ing | depth | including | in | per | | Sewer. | | |10-cm. | of | back- |laying | linear | | | | |(4-in.) | sewer | filling, |(includ-| meter. | | | cm. | in.|branches| | removing | ing | | | | | |every | m. | surplus, |hauling,| | | | | |4-1/2 m.| | etc. | etc.). | | | | | |Pesos. | | Pesos. | Pesos. | | +----------+------+----+--------+-------+------------+--------+--------+ |Fire-clay | 24.3 | 8 | 2.00 | 2.10 | 3.46 | 0.21 | 5.67 | | " | 25.4 | 10 | 2.78 | 2.25 | 3.97 | 0.2625 | 7.0125 | | " | 30.5 | 12 | 3.64 | 2.50 | 4.705 | 0.305 | 8.65 | | " | 38.1 | 15 | 6.14 | 2.75 | 5.50 | 0.4375 |12.0775 | | " | 45.7 | 18 | 8.80 | 3.00 | 6.745 | 0.645 |16.19 | | " | 50.8 | 20 | 11.30 | 3.50 | 8.275 | 0.815 |20.39 | |Concrete | 55.9 | 22 | 5.93 | 3.50 | 9.19 | 1.325 |16.445 | | " | 61.0 | 25 | 7.30 | 3.75 | 11.245 | 1.685 |20.23 | |One brick}| | | | | | | | |thick on }| 68.6 | 27 | 7.17 | 3.75 | 11.735 | 3.93 |22.835 | |concrete }| 76.2 | 30 | 7.925 | 4.00 | 14.53 | 4.515 |26.97 | |founda- }| | | | | | | | |tions }| | | | | | | | +----------+------+----+--------+-------+------------+--------+--------+

The house connections are chiefly of 10-cm. (4-in.) pipes, laid on a minimum gradient of 2-1/2%, from oblique branches on the sewer to siphon intercepting traps near the house, as shown by Fig. 17. From this trap a 10-cm. fire-clay inspection pipe is carried up and capped at the sidewalk level with a cast-iron box having a locked cover. From this inspection pipe a branch is connected to a cast-iron fresh-air inlet, in most cases set in the wall of the house, the inlet being 30 cm. above the level of the pavement.

_Effect of the Flood on Sewers._--The flood of August 27th and 28th, 1909, partly destroyed one of the main collectors, which was laid along the banks of the river and encased in concrete. This has now been relaid farther north, and out of the way of any future floods. The total length of the new sewers replacing those damaged amounts to 1200 m., and they vary in internal diameter from 20 to 55.9 cm. (8 to 22 in.).

MAIN OUTFALL SEWER.

The direction of the main outfall sewer was determined after a thorough study of all the available land lying to the north and northeast of the city, as it was the intention of the Company to utilize for irrigation purposes the sewage and any surplus waters that might be developed. The best available site was found to be about 12 km. north of the city, a little northwest of the village of San Nicolas de los Garzas, as shown on Plate II. The long length of outfall required was justified by the cheap cost of the land and its excellent character for sewage irrigation. The sewer was designed for a capacity of 90,000,000 liters a day (36.76 cu. ft. per sec.) in order to allow for conveying surplus waters as well as sewage.