35 



studies, but will prove a valuable safeguard against drawing erroneous 

 conclusions in respect to the life of any class of piling. 



Service records are entered this year for 30 installations not en- 

 tered in last year's report, involving over 23,000 piles in 27 installations, 

 with 3 installations for which it has not yet been possible to obtain 

 the exact data on number of piles installed- This data, however, is 

 in most cases promised and will be obtained, it is hoped, in the far- 

 ther progress of the work. There are also certain unavoidable dis- 

 crepancies between this report and last year's in the number of piles 

 entered for some of the structures covered by both reports. This 

 year, also, the policy has been adopted of using only the service record 

 of bearing piles, since fender piles, of which many were entered in 

 the record of last year, are subject to such special hazards as seldom 

 or never to show a life which is representative of the service rendered 

 by the same class of pile in bearing service. 



Perhaps the most important result of the increased volume of ser- 

 vice records presented this year is that the average life of creosoted 

 piling indicated by them is lower than that recorded last year. This 

 does not, in the view of the Committee, indicate that creosote treatment 

 is less valuable than was stated in last year's report, although the 

 statement of the Committee last year has been misinterpreted in some 

 quarters as promising for creosoted Douglas fir piling, as now used, or 

 for structures as a whole, the extreme life shown by the best examples 

 taken from the Oakland Long Wharf. Creosoted piling as now com- 

 monly found in marine structures is far from being piling "properly 

 handled in rafting, and not mistreated in the erection of the substruc- 

 ture" which was predicated in the la^t year's statement of the Commit- 

 tee. 



Rather, in view of the very striking evidence given by the Harbor 

 Commission report, that of all the damage to piling noted and repaired 

 in this year's complete inspection 80 per cent was definitely caused 

 by dog holes (Plate 4, Fig. 2) through which the borers plainly gained 

 their entrance, do the service records now presented strengthen the 

 emphasis laid last year upon the critical necessity of care, both in the 

 handling of creosoted piling from the treating plant to the structure 

 and in driving it and building the superstructure upon it. Unquestion- 

 ably the use of poor oil or improper methods of treatment may also 

 shorten the life of creosoted piling and should be guarded against by 

 proper specifications. Thin treatment on one side of the pile (Plates 

 5 and 6) sometimes result when the piles are rafted before being treat- 

 ed, if the moisture is not properly removed in the treating process. 

 The evidence is also thoroughly established that knots frequently afford 

 points of entrance for borers (Plate 7, Fig. 1). The evidence of such 

 examples as the Oakland Long Wharf as to the life which a proper 

 creosote treatment, properly safeguarded in subsequent handling and 

 construction, may give to wooden piling still stands. Creosoted piling 



