DEAINAGE METHODS FOE COUNTY EOADS. 



27 



instead of the drop inlet and catch basin sho^Yn in figures 8 and 9. 

 The dimensions shown in the figures are considered minimum for 

 good practice, and it may be necessary to increase them where the 

 vohime of water to be cared for is large. 



The photograph in Plate III shows a cast-iron grating suitable 

 for covering either a catch basin of the design shown in figure 9 or 

 a drop inlet of similar design. Where these structures' are suffi- 

 ciently far removed from the traveled way to obviate danger to 

 traffic the cover design in figure 8 may be used. The practice of 



z'-r 



B-B 



CONCRETE V' END WALL 



FOR PIPE CULVERTS 



^10"— 





2- 









— 10'^ 



4 



























J- / 



—^ -A 







= _ 





j 









-* 



4-0'^ 







Fig. 10. 



PLAN 



leaving the tops open always is objectionable on account of danger 

 to animals, and also because the opening becomes obstructed with 

 sticks, leaves, etc. 



COSTS. 



Such structures as are shown in figures 8, 9, and 10 usually may 

 be constructed of 1:2:4 concrete at a cost of from $12 to $18 per 

 cubic yard, including all form work. The labor cost per cubic 

 yard should seldom exceed about $10. 



The cost of suitable cast-iron covers, where standard designs are 

 employed, averages about 2| cents per pound in place. 



