ConstkUct^io]^ op HartHen Damj^. 



251 



soil from the embankmeut and so weakening the structure. Only a 

 well-packed and properly built pitching will therefore suit the 

 purpose. 



(h) Waste Weir or Overspill. — If the conditions laid down in 

 section (e) of part (1) above are present and the ideal site for the 

 Wtjste weir, a " nek," is available, the only work necessary will be 

 to excavate this nek to the full-supply level of the reservoir and to 

 such a width as to enable the expected maximum flood to pass 

 through. The bed of the waste weir must be of rock or hard souiid 

 insoluble material, otherwise masonry check walls, along the length 



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of the waste weir and carried down to good hard foundation, will be 

 needed to prevent the flood water scouring the bed and thus lowering 

 the full-supply level of the reservoir. If the foundations for these 

 check masonry walls are not present or are too deep to justify the 

 expense of carrying them out, a dry-stone wall hand-packed in a 

 wire net made of No. 8 galvanized wire, and having a 6-inch mesh, 

 may be substituted. Behind these dry-stone walls a dry-stone pitch- 

 ing made in a similar wire net, and about 15 feet wide, is made to 



