| Total. | Per lb. | |
| Cost of placing | $172 | 0.1986 ct. |
| Cost of bending | 52 | 0.06 ct. |
We can now summarize the cost of the concrete work proper of this sewer as follows:
| Items. | Per cu. yd. |
| Cement, sand and stone | $3.67 |
| 55 lbs. steel at 2 cts. | 1.10 |
| Forms, labor and materials | 1.25 |
| Mixing and placing concrete labor | 0.74 |
| Placing steel at 0.1986 ct. per lb. | 0.11 |
| Bending steel at 0.06 ct. per lb. | 0.03 |
| Moving forms | 0.25 |
| —— | |
| Total labor and materials | $7.15 |
To get the total cost of the sewer proper we must add the cost of the vitrified brick invert paving. There were 71 cu. yds. of this paving and its cost was as follows:
| Per cu. yd. | |
| 0.6 bbls. cement at $1.80 | $1.08 |
| 0.25 cu. yd. sand at 75 cts. | 0.19 |
| 450 bricks at $12 per M. | 5.40 |
| Labor laying, 71 cu. yds. at $180.33 | 2.54 |
| —— | |
| Total | $9.21 |
None of the preceding figures includes the plant charges. The plant cost $12,000 and the cost of running it during the work described was $2,000. In explanation it should be noted that the plant served for building some 1,340 lin. ft. of 27-ft. sewer as well as for the section described.
SEWER AT MIDDLESBOROUGH, KY.—In constructing an oval sewer 4 ft. high at Middlesborough, Ky., two steel forms in 10-ft. sections were used. As shown in Fig. 263, T-iron ribs were spaced 5 ft. apart, fastened together at the top by longitudinal angle irons, and at the bottom by a sheet of steel 22 ins. wide, forming the bottom of the invert. The lagging for the sides consists of movable 5-ft. lengths of channel iron, secured by sliding bolts. After the bottom of the trench has been roughly shaped with concrete, a 10-ft. section of invert forms is lowered and suspended by the cross-beams, and the space beneath packed with concrete; then a channel iron is slid into place and bolted, and concrete packed behind it, and so on until the invert is made. The next 10-ft. section is then built while the first is hardening. Upon the completion of the second section, the channel iron sides of the first section are removed, and then the rib framework is lifted out. Wood arch centers are then put in place and an inch of 1:2 plaster spread over the lagging before placing the concrete for the arch, which is 6 ins. thick.
Fig. 263.—Invert Form for Sewer Construction.
The cost per 100 ft. of this sewer was as follows (prices being assumed for cement and labor):