fender piles and wales at the top of wood groins. These are frequently 

 located at or below the water level. The planks of Wakefield piling used as 

 a groin and wood cribbing below water are other examples. 



When timber and lumber are used above the water but near enough to be 

 frequently wetted by splash and spray they would be in the spray or splash 

 zone. Pier decks and wood fittings such as handrails are frequently in this 

 use zone. Timber bulkheads and cribbing above water are also frequently in 

 the splash zone. 



Where wood is used away from the immediate contact with saltwater or 

 its splash and spray, two different treatments are called for. They are 

 pressure treatments that have different retention requirements depending on 

 whether the wood is placed in contact with the soil or above the soil in 

 air. Retention requirements for these uses are shown on Table 33. 



Examples of wood in contact with soil would be bulkheads and retaining 

 walls using Wakefield piles or horizontal planking supported by vertical 

 piles. Sometimes boardwalks are incorporated into a bulkhead structure and 

 these frequently are in firm contact with the soil. Sand fences and cribs 

 placed above the tide line are usually in direct contact with the soil. 



Wood in air is probably best visualized in causeway decking (far enough 

 removed from the water to be free of the direct influence of splash and 

 mist) buildings, towers, navigation aids and other such structures built on 

 piles or concrete foundations. Whatever the foundation, wood in air must be 

 clear of the ground by at least 200 millimeters (8 inches) and well venti- 

 lated. In the southern United States or in especially warm and moist 

 climates, additional clearance should be considered (ASCE, 1975). 



(2) Preservative Retention Standards . The adequacy of preservative 

 treatment may be determined by the quantity of preservative retention or by 

 its penetration into the wood. 



(a) Retention By Assay . The quantity of preservative required 

 for adequate protection is given by the American Wood Preservers Association 

 (AWPA) in pounds per cubic foot (pcf) . The retained quantity is measured 

 by assaying the contents of core samples. 



Timber and lumber used in submerged locations should be pressure treated 

 using the full cell process to achieve retention equal to or greater than 

 the amounts shown in Table 33. In those parts of the world where teredo and 

 pholad attack is expected and where Lirrmoria tr-ipunotata attack is not 

 prevalent, creosote or creosote-coal tar treatment will provide adequate 

 protection. Where L. tripunatata attack is expected, and where either 

 teredo or pholad attack is expected, the dual treatment with creosote or 

 creosote-coal tar and either CCA or ACA preservatives to the retentions 

 shown on Table 34 will give the best protection known (AWPA C3) . 



Timber and lumber in the splash zone can be protected by using either of 

 the oil base preservatives, creosote or creosote-coal tar or one of the 

 waterborne preservatives CCA or ACA to the retentions shown on Table 33. 

 The creosote or creosote-coal tar preservatives are. usually preferred 

 because the waterborne preservatives are subject to leaching. 



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