18 



Still another type of concrete protected pile developed in 1908 is 

 the "Black Patent" type in which concrete is placed in sectional forms 

 above the water level which are lowered on the pile as the filling of the 

 form proceeds. Two small contracts for this protection were let in 

 1908-9; the remaining piles of which have been inspected and recorded 

 in the tabulated service records. In general these piles appear to be 

 sound to the mud line and those which have failed have been eaten off 

 at the mud line because the protection was not carried below that 

 point. 



During the period from 1900 to 1910 while experimenting with the 

 various concrete supports outlined above, the Board also continued to 

 utilize considerable quantities of green piles, coated piles and creo- 

 soted piles. In 1908, 1200 eucalyptus piles, all of which were Euca- 

 lyptus globulus according to the report of the engineer, were purchased 

 and driven largely in the Ferry Slips. These- piles were a disappoint- 

 ment for this purpose, failing partly by breakage and partly by the 

 attacks of Xylotrya. They were all replaced by 19-12. Four of these 

 piles, however, installed as mooring and fender piles in Pier 38 have 

 been in place to date. These piles have been cut off by Xylotrya, at 

 the mud line, but show very little of the characteristic limnoria attack 

 at low water line. 



All of the coated piles driven during this period have been replaced 

 or removed, a typical example being Pier 9. This pier originally of 

 green piles was rebuilt with coated piles in 1903. The coated piles 

 were replaced with creosoted piles in the period from 1911 to 1915. 



Most of the creosoted pile construction of this period (1900-1910) 

 has likewise been removed or replaced. This construction included the 

 timber bulkhead wharves along the seawall which have been recently 

 reconstructed as concrete bulkhead wharves. Replacement was neces- 

 sitated both by deterioration of the creosoted piles and the decay of 

 the timber decks. There are a number of creosoted piles installed 

 during this period now in use in the ferry slips but they are so inter- 

 mixed with newer construction that a survey and report is unreliable. 

 The earliest creosoted pile structure which has been maintained intact 

 is the freight slip extension to Pier 36 constructed in 1909. These 

 piles are in fairly good condition as noted in the* appended tabulation. 

 Next in length of service are the creosoted piles used in repiling of 

 piers 7 and 9 and in the track extensions of piers 20 and 21 installed 

 about 1912. 



During the years 1914-16 a very extensive creosoted pile program 

 was carried out by the Board. This program included the repiling of 

 Piers 11, 19, 21, 23, 25 and 27 and -the construction of Piers 14, 15, 16, 

 18, 20, 22, 37, 41 and 46. During the past year most of this construc- 

 tion has been carefully inspected and considerable repairing has been 

 carried out in the way of plugging the holes between tides, which 



