(Lehotsky, 1941; McLaughlin and Brown, 1942). All of these worked satis- 

 factorily provided the pickets were placed so as to provide 25- to 50- 

 percent porosity and were securely anchored in the sand. It was neces- 

 sary to keep the top of the fence even to produce a uniform dune ridge. 



Extensive use has been made of brush fences constructed either by 

 burying the basal end of the brush in a trench or by clamping the brush 

 together between poles or strips (Stratton and Hollowell, 1940) and 

 fastening the units to posts, similar to the present wooden slat-type 

 fence. Properly designed brush fences are very efficient sand trappers. 

 Savage (1963) found them superior to the slat type but almost twice as 

 expensive because of the high labor requirements. With the increase in 

 labor costs since then, brush fences and the various versions formed by 

 individual pickets have largely been replaced by prefabricated fences 

 made from either wood or fabric. 



(1) Slat Fence . The standard slat fence is constructed of 

 wooden slats 1 centimeter by 3.8 centimeters by 1.2 meters, spaced 3.2 

 to 3.8 centimeters apart, held together by four or five double wires, 

 twisted between each slat (Fig. 7). If durability is needed, wood may 



be treated with preservative and coated wire used. However, if the fence 

 is effective, it is usually completely covered before serious deteriora- 

 tion occurs. If the cutting of the fence to form a 60-centimeter height 

 is a possibility, the four-wire version is preferable. Fence is normally 

 packaged in 15.2-meter rolls for ease of handling. 



Slat fence is attached to posts for support. Various types of posts 

 have been used but the standard arrangement (Savage, 1963) involves the 

 use of 5.2-centimeter by 10.4-centimeter by 1.8-meter posts made from 

 less expensive grades of lumber, set 60 centimeters deep, spaced 3 meters 

 apart, with diagonal 2.5- by 15-centimeter braces at 9- to 12-meter inter- 

 vals and on ends (Fig. 8). The fence wires are stapled to the posts. 

 Where sand is exceptionally soft, it may be necessary to set posts deeper 

 than 60 centimeters which usually increases the difficulty. Galvanized 

 pipe has been used as posts and removed after the fence fills. 



Slat fence is usually installed with the bottom at ground level. 

 The effective height can be increased by raising the fence 30 centi- 

 meters above the ground but the fence will not fill as early and will 

 be more susceptible to storm damage. The use of the 1.8-meter fence is 

 usually impractical due to the effort required to set posts deep enough 

 to support it. 



The slat fence is fairly easy to install. A six-man crew, with 

 materials available at the site and using a mechanical post-hole digger, 

 can install 12.2 meters of fence per man hour. The present cost (1978) 

 of the standard 1.2-meter slat fence, in quantity, is about $1.25 to 

 $1.50 per meter. 



(2) Fabric Fence . A number of fabrics made of weather-resistant 

 synthetics have been used to construct sand fences in recent years (Fig. 9) 



16 



