brush, cane, bamboo, and reeds have all been used to make devices to control 

 water currents, stabilize bottom sediments or to control dry sand buildup. 

 Where these wood forms are indigenous to the area or readily available they 

 can be valuable materials. 



b. Offshore Structures. 



(1) Breakwaters and Caissons . Wood is seldom used in offshore 

 structures of this type but dimension lumber and wet use plywood may be used 

 for navigation aids or other incidental small structures that may be mounted 

 on offshore breakwaters and caissons. 



(2) Pile Dolphins. Wood is frequently used offshore for pile 

 dolphins and other mooring or anchorage devices such as guide piles for 

 floats or piles for channel markers. Pile dolphins are clusters of wood 

 piles tied together as in Figure 71. 



(3) Floats. Wood is used extensively in the construction of 

 floating structures. Although the tendency is toward synthetic materials 

 for small flotation devices, wood remains the most used material for framing 

 flotation units and providing a platform for access and mooring fastenings. 

 Wood flotation units such as logs could be used to form floats or booms for 

 the containment of surface debris. 



c. Shore-Connected Structures . 



(1) Breakwaters and Jetties. Wood uses in shore-connected break- 

 waters and jetties would be the same as described for offshore structures. 



(2) Groins . Wood is frequently used in the construction of groins. 

 Wakefield sheet piles are commonly seen used as shown in Figure 61. The 

 sheet piles are secured with timber wales at the top. Wood planks spanning 

 between wood piles create another type of groin structure as seen in Figure 

 76. 



(3) Bulkheads . Wood bulkheads are usually one of two kinds. 

 Wakefield sheet piles are driven along the bulkhead line and tied back to 

 the embankment by timber wales and tie rods to imbedded anchors (deadmen) . 

 Otherwise, vertical piles acting as soldier beams are driven at regular 

 intervals along the bulkhead line and wood planks are placed to span hori- 

 zontally between them. Piles can be tied back to deadmen. 



(4) Revetments . 



(a) Pile Revetment . Slopes can be stabilized using parallel 

 piles laid along the slope as shown in Figure 77. Piles used this way 

 must be securely tied to headers or staked down. 



(b) Fascine Mattresses . The word "fascine" comes from the Latin 

 "fascina" meaning a bundle of sticks. Fascine mattresses are used as 

 submerged scour aprons and as filter blankets along revetments. There are 

 many ways to construct the blankets but they basically all consist of 

 sticks tied together in bundles and arranged in mattresses about 20 meters 

 (62 feet) wide and up to 200 meters (620 feet) long. The mattresses are 



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