CONSTRUCTION. 2^ 



ters is there more opportunity to show good judgment than 

 in judiciously disposing of surface water about cuts. All cuts 

 must have surface ditches and thorough drainage. 



In turning streams care must be taken to make embank- 

 ments across old channels strong enough to resist the action, 

 of currents. In such cases the width of the embankment 

 should usually be made not less than ten (10) feet from the 

 center line on the side against which the current will act, with 

 slope of two to one. In cases of soft, spongy, or sliding mate- 

 rial, this width should be increased on the exposed side. It 

 should be borne in mind that it is less costly to build an em- 

 bankment with excess of strength at first, than to have it 

 washed out and be compelled to rebuild it. 



In turning rapid, turbulent streams, take special and full 

 precautions to prevent the new embankments from being 

 washed away while building before they are high and strong 

 enough for effectual resistance. 



In building culverts and other waterways of perishable ma- 

 terials, ample allowance in size must be made for reconstruct- 

 ing them at a future time of durable materials. Wherever 

 practicable iron culvert pipes should be hauled ahead and 

 placed in position before the embankments are completed. 



Vitrified tile pipe of double strength will be used under road 

 crossings. 



In building permanent box culverts of stone or brick, the 

 smallest opening to be allowed is 9 sq. ft., clear of all obstruc- 

 tions. The height of the opening of a culvert should never be 

 less than its width. The greatest care should be taken to 

 secure the foundations of all culverts and water conduits. 



Stream diversions, even when of considerable magnitude, 

 usually prove much cheaper in first cost and also in subsequent 

 maintenance than the bridging otherwise required, particu- 

 larly when the excavated material is used in embankments. 



The natural "scour" of the stream may sometimes be relied 

 upon to widen channel excavations of small original cross- 

 section, but in all cases due precautions must be taken to in- 

 sure final cross-sections of full and ample proportions. 



Pile and trestle bridges, not required in part or in whole for 

 water-way, are too frequently constructed in order to save 



