The trenches were excavated 5 cm. below the required finishing depth, to allow for grading the pipes in selected material, and were taken out to an average width of 40 cm. greater than the outside diameter of the pipe, to allow for their proper jointing, and also to give sufficient room to roll the pipes in the trenches.
The final quantities of excavation were:
| Trench: | No. 1 | 11,115 | cu. m. |
| No. 2 | 18,096 | " | |
| No. 3 | 6,650 | " | |
| ——— | |||
| Total | 35,861 | cu. m. | |
| Roadways: | No. 1 | 4,165 | cu. m. |
| No. 2 | 1,999 | " | |
| No. 3 | 30 | " | |
| ——— | |||
| Total | 6,194 | cu. m. |
The route of the pipe line was laid out so as to obtain an average fill of not more than 1 m. over the tops of the pipes, but in some cases the cuts, for short lengths, were 3 m. deep. The excavation for this work began in June, 1907.
Hauling Pipes.—The pipes were hauled to the site of the work with ox-carts and mule teams. The cost of hauling varied from 25 cents per pipe at the lower end, to 1 peso per pipe at the upper and, comparatively speaking, inaccessible portion of the line. The weight of each 55.9-cm. pipe was about 182 kg.; that of each 63.5-cm. pipe was about 216 kg.
The breakages in all the pipes cast at the pipe yard amounted to about 1%, due chiefly to unloading them carelessly near the pipe line.
Pipe Laying.—The pipe-laying gang was composed of 7 Mexicans under the direction of an American foreman, who was in charge of several gangs. One gang could lay daily from 60 to 73 m. (from 100 to 120 pipes). The following was the ordinary pay-roll for one gang:
| 1 Foreman at 8 pesos (proportion). | 2.00 | pesos. |
| 1 Pipe layer at 3 pesos. | 3.00 | " |
| 1 Pipe layer's assistant at 2 pesos. | 2.00 | " |
| 1 Cement mixer at 2 pesos. | 2.00 | " |
| 2 Outside plasterers at 2.50 pesos. | 5.00 | " |
| 2 Inside plasterers at 2.25 pesos. | 4.50 | " |
| 1 Water boy at 0.50 peso. | 0.50 | " |
| ——— | ||
| Total. | 20.00 | pesos. |
This brings the average cost of laying the pipes to 32.8 cents per lin. m.
The pipes were jointed with 1:2 cement mortar, the outer joint being rounded over both pipes for a width of 121⁄2 cm. (5 in.) and a height of about 19 mm. (3⁄4 in.). In making these joints the pipe layers wore rubber gloves. The joints were kept moist, and the trench was back-filled with fine, screened material to a depth of 10 cm. above the top of the pipe. Inside, the joints were carefully caulked with cement and rendered smooth, the plasterers working continuously along with the pipe layers, doing from 20 to 35 m. at a time. Water had to be conveyed to the trenches by barrels on burros, and during the dry season it was sometimes carried 5 or 6 km.