J^f^,. 



--*- ^ 



Figure 6-26. Erecting snow-type sand fencing. 



centimeters in width. The standard wooden snow fence appears to be the 

 most practical and cost effective. 



(b) Only straight fence alinement is recommended (see Fig. 6-27). 

 Fence construction with side spurs or a zigzag alinement does not increase 

 the trapping effectiveness enough to be economical (Savage, 1962; Knutson, 

 1980) . Lateral spurs may be useful for short fence runs of less than 150 

 meters (500 feet) where sand may be lost around the ends (Woodhouse, 

 1978). 



(c) Placement of the fence at the proper distance shoreward of the 

 berm crest may be critical. The fence must be far enough back, from the 

 berm crest to be away from frequent wave attack. Efforts have been most 

 successful when the selected fence line coincided with the natural 

 vegetation or foredune line prevalent in the area. This distance is 

 usually greater than 60 meters shoreward of the berm crest. 



(d) The fence should parallel the shoreline. It need not be 

 perpendicular to the prevailing wind direction and will function even if 

 constructed with some angularity to sand-transporting winds. 



(e) With sand moving on the beach, fencing with 50-percent porosity 

 will usually fill to capacity within 1 year (Savage and Woodhouse, 

 1969). The dune will be about as high as the fence. The dune slopes will 

 range from about 1 on 4 to 1 on 7 , depending on the grain size and wind 

 velocity. 



(f) Dunes are usually built with sand fencing in one of two ways: 

 ( 1) By installing a single fence and following it with additional 



6-39 



