DEAIISTAGE METHODS. FOR COUNTY ROADS. 37 



COST OF CONSTRUCTING TILE DRAINS. 



Tlie cost of laying tile drains, including necessary ditching and 

 back filling, varies largely on account of variations in costs of mate- 

 rial and labor, as already indicated. Where stone occurs in the ditch, 

 or where any other condition makes excavation unusually difficult, the 

 cost will be increased substantiall}^ Where the soil is unusually 

 soft, it is necessary sometimes to place boards in the bottom of the 

 ditch to keep the tile from settling out of line, and in this case the 

 cost of laying the tile, including the purchase of the boards, will be 

 increased still further. In the rare cases where the conditions are 

 such as to make it desirable that the ditch be entirely back filled with 

 crushed stone or gravel so that the tile may do its work to the best 

 advantage the cost of stone oi- gravel may be considerable. The addi- 

 tional cost of handling such cases would depend, of course, on the 

 availability of the materials used in the back fill. In some cases the 

 total cost, including all labor and material, has exceeded $50 per 

 100 feet, although $10 to $12 per 100 feet are commoner figures for 

 ordinar}^ tile drain. 



f Blind drainJ 



V-Drain constructed of field stoni or gravel wnere foundation is defective. Ootids to side ditclies eveT7 50 feet 

 Ditches to be of sufficient depth to drain V- drain 



V-DRAIN 



Fig. 13. 



Suitable head walls and outlets for tile drains may be constructed 

 at small cost. The design shown in figure 12 ordinarily can be built 

 at a cost not to exceed $5 or $6. In some cases stone masonry may 

 be employed at even a smaller cost. 



V -DRAINS. 



The V-drain shown in figure 13 and Plate V is especially adapted 

 to localities where field stones can be obtained cheaply and in abund- 

 ance. This type of drain is very effective when constructed properly 

 and has the advantage that in addition to draining the subgrade of 

 the road it provides an excellent foundation for the road surface. Its 

 first cost is high when compared with the various types of side drains, 

 but usually is much lower than the cost of side drains and Telford- 

 foundation combined. The latter comparison is, in general.^ tlie more 

 reasonable one to make, because under favorable conditions a V-drain 

 may serve to replace the combination of Telford foundation and side 

 drains, and would be used seldom, if ever, where only drainage is 

 needed to produce a stable foundation. 



