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MOSQUITO ERADICATION 



a concrete core-wall in the fill, so as to avoid any possibility of 

 leakage along the pipe. 



The following description of a large drainage job, covering 

 5,600 acres of Columbia River overflow land is compiled from 

 information furnished by the company: 



(Photos by California Corrugated Culvert Covipany) 

 Fig. 107. — Installing a 7-ton Calco culvert and drainage gate, Columbia River 



project. 



Two sloughs were selected for the drainage outlets. At one 

 of these, a battery of five Calco gates, attached to five corrugated 

 culverts, 6 feet in diameter and 110 feet long, were placed side 

 by side. A row of piling, 8 feet on centers, intercepted each 



