25 



TYPE Pre-cast Concrete pile construction: 



Date Number of 

 structure Constructed Supports Condition 1921 



Pier 17 1911 135 41 Piles show rusting cracks 



Bulkhead over the steel above the high 



Wharf water line. Otherwise, in first 



class condition. 



Section 11-A 1912 141 36 Piles show rusting cracks 



Seawall above high water. Otherwise, 



all piles in good condition. 



Pier 35 1915 2492 56 Piles badly cracked above 



high water. 215 Piles slightly 

 cracked above high water. Other- 

 wise, piles in good condition. 



Untreated Wooden Piles 



Definite service records have this year been tabulated for a large 

 number of untreated wooden pile structures not listed last year. The 

 striking fact brought out is that every pile reported last year has 

 been torn out or replaced, and that practically all those now listed 

 have been likewise disposed of, except those, as in some cases, which 

 were revamped by the concrete jacket method. 



That the results to be obtained with untreated piles are directJv 

 governed by their exposure has been very forcefully demonstrated in 

 the experience of the San Francisco-Oakland Terminal Railways. Their 

 original trestle was constructed in 1902 on untreated piles and for a 

 period of five years was equal to all demands. From this time forward 

 the severity of attack was increasingly pronounced. In the year 1913 

 some 30 untreated anchor piles were destroyed in a single season. 

 This would seem to indicate that an untreated pile structure in a lo- 

 cation isolated from structures known to be harboring marine pests can 

 be expected to last considearbly longer than an untreated pile struc- 

 ture in close proximity to structures known to be infested: This is 

 true in spite of the fact that the marine pests are present at all times. 

 Untreated piles are also more severely attacked at the outer end of 

 piers, or in deep water, than they are inshore or in shallower water. 



This condition is very often altered by unusual local influences. 

 The experience of the Howard Company of Oakland illustrates the 

 point. Their original pier was built upon untreated piles in 1900 and 

 required little or no attention for about 8 years. They were so pleased 

 with the results obtained with this type of cheap construction that re- 

 placements were made with untreated piles. During these years the 



