POLES AND PILING 321 



Much of our piling is only temporary in its requirements, such, for 

 example, as for temporary trestle and bridge construction, false work, 

 etc. For such purposes almost any species may be used. For wharf, 

 dock, trestle or other construction in the warmer salt waters (south of 

 Delaware Bay on the Atlantic Coast and the entire Pacific Coast up to 

 British Columbia) the danger from marine borers is so great that un- 

 treated or unprotected piling may be riddled and rendered useless in 

 from one to four years. 



White oak, Douglas fir and longleaf pine are the principal timbers 

 used for piling purposes where great strength and durability are required. 

 When exposed, untreated, to the usual conditions of decay, such, for 

 example as wharf or dock piling, trestlework, etc., but without the pres- 

 ence of marine borers, these woods should remain in service for from 

 seven to eleven years. Other less durable species must be replaced in 

 from four to seven years depending, of course, upon the local conditions 

 of decay, abrasion, etc. 



THE PRESERVATIVE TREATMENT OF POLES AND PILING 



Consumers of poles and piles are actively taking up the work of pre- 

 servative treatment to prolong their life in service. It has not only been 

 demonstrated that the increased cost due to treatment is more than 

 justified in the longer service rendered, but when the cost of taking out 

 old poles, replacing them with renewals together with the cost of restring- 

 ing the wires are taken into consideration, there is a great annual saving. 

 Even the most durable poles are now being treated before placement. 

 Within the past decade the amount of poles and piling that has been 

 subjected to preservative treatment has more than doubled. 



Inasmuch as poles deteriorate from decay most rapidly at the ground 

 line it is only necessary to treat that portion of the pole which extends 

 from the butt up to a point about 6 in. above the surface of the ground. 

 Many methods of artificially treating the pole or providing for its setting 

 in the ground have been experimented with. Among these are: (a) 

 charring by means of painting with crude oil and setting fire to it; (b) 

 brush treatment or coating with creosote or other toxic preservative; 

 (c) setting in a collar of concrete or crushed stones. The first two 

 (a) and (b) will probably prolong the life of a pole from two to six years 

 but the last named (c) does not justify the additional expense incurred. 



In all cases, poles should be thoroughly air seasoned before being 

 subjected to any form of artificial preservative treatment. 



