DEAINAGE OF lERIGATED SHALE LAND. 



23 



With labor at $0.25 per hour, actual unit costs for excavating, lay- 

 ing tile and back-filling trenches in shale ranging from 6 to 7 feet 

 in depth averaged $0.12 per linear foot on four small projects aggre- 

 gating a total of 4,430 feet of trench. A contract job of 2,768 feet 

 of 7-foot trench was let for $0.20 per linear foot, while another job 

 of 5,600 feet, running 6 feet in depth, was let so as to average about 

 $0.11|^ per linear foot. These figures do not include the cost of 

 boring relief wells in the bottoms of the trenches. However, taking 

 the work as a whole, this need not increase the cost by more than 

 an average of $0.02 per foot, as there are nearly always some por- 

 tions of trench on any job in which the relief wells are not essential. 

 The cost of boring the relief wells probably averages about $0.05 

 per linear foot of well where the depth below the bottom of the 

 trench runs from 8 to 16 feet. Where the depths vary from 16 to 

 25 feet the cost per foot of well may run as high as $0.10, especially 

 if much sand rock, lime rock, or other hard material be encountered 

 that renders necessary the use of a drill. 



The acreage costs of drainage of the affected portions of those 

 projects referred to in this bulletin have been high. This is due in 

 part to the relatively high cost of trenching, but the chief reason 

 is the frequency of drains required, as will" be noted by referring to 

 the maps of the several tracts. Based on the actual affected areas, 

 the costs have ranged from $13 to $100 per acre. Almost invariably, 

 however, at the time of drainage the trouble was spreading rapidly, 

 so that the cost in most instances should in all fairness be dis- 

 tributed over the area afforded protection as well as over that directly 

 benefited. As a matter of fact much of the real value of the drain- 

 age of shale lands is the benefit that accrues from arresting the de- 

 velopment of the trouble. This is especially true because of the very 

 serious alkali problem that results when the lands are allowed to re- 

 main in a water-logged condition for any considerable length of 

 time. Once the alkali salts have accumulated in the soil to an 

 extent that renders the land wholly unproductive, it becomes very 

 difficult to bring the land under satisfactory cultivation again. Es- 

 sentially, then, the most practical way to make this type of drainage 

 both economical and satisfactory is to install the drains at the very 

 first indication of trouble. 



EXAMPLES OF METHODS. 



EXAMPLE I. 



The area of very wet land as indicated on the map in figure 2 

 aggregates about 22^ acres. Much of this was actually covered with 

 water, and in but few places was it more than two feet from the 

 ground surface to water. These 22^ acres by no means represent 



