EXCAVATING MACHINERY USED IN LAND DRAINAGE. 23 



COST OF OPERATION. 



A drag-Tine excavator of the rotary type, having a 2-yard scraper 

 bucket and a 60-foot boom, was used in the construction of some 

 drainage ditches in southern Texas. It was built mostly of wood and 

 moved on rollers. Power was derived from an 80-horsepower internal- 

 combustion engine, burning oil. The cost of the excavator, ready to 

 operate, was $12,000. It was operated about 10 months in two daily 

 shifts of 10 hours each, a shift consisting of 10 men. The actual 

 working time was not recorded. The ditch ranged from 4 to 22 feet 

 in bottom width, from 3 to 12 feet in depth, and had 1 to 1 side 

 slopes. The soil varied from a stiff, heavy clay to a fine sand. The 

 excavation amounted to 230,000 cubic yards; the cost was as follows: 



Operating expenses $22, 313. 36 



Miscellaneous expenses 374. 70 



Interest and depreciation 4, 100. 00 



Cost per cubic yard, $0.1164. 26 ' 788 " 06 



On another drainage project in southern Texas, a 2-yard rotary 

 excavator was used. The machine was of steel throughout, had a 

 60-foot boom, and was mounted on caterpillar traction. The crew 

 consisted of a foreman, operator, engineman, oiler, and two laborers. 

 The machine was operated by a 110-horsepower internal-combustion 

 engine, with oil as fuel. The total cost of the machine was about 

 $17,500. The cost of erection was $509. During the four months of 

 operation two 10-hour shifts were run. The ditches ranged from 4 to 

 22 feet in bottom width and from 3 to 12 feet in depth, with 1 to 1 

 side slopes and 8-foot berms. The material excavated was a stiff, 

 heavy clay. The excavation amounted to 91,400 cubic yards; the 

 cost was as follows: 



Operating expenses $8, 873. 82 



Miscellaneous 371. 00 



Interest and depreciation 2, 391. 00 



Cost per cubic yard, $0.1273. U ' 635 - 82 



In the same general locality as the last example a lj-yard rotary 

 drag-line excavator, operated by a 50-horsepower internal-combustion 

 engine and mounted on caterpillar traction, was used in the con- 

 struction of some ditches in soil ranging from stiff, heavy clay to fine 

 sand. The ditches were of the same dimensions as in the foregoing 

 example. The machine was rebuilt from an old dipper dredge at a 

 cost of about $1,200. It was operated in two daily shifts of 10 hours 

 each. The crew for each shift consisted of from 5 to 6 men. During 

 the five months of operation the machine moved 59,014 cubic yards 

 at an expense, exclusive of interest and depreciation, of $8,921, or 

 $0.1512 per cubic yard. 



