28 



effluent from a gas plant at the foot of Market St., Oakland, was being 

 discharged into the Estuary and the useless by-products from the man- 

 ufacture of illuminating gas were deposited by tidal currents as a sur- 

 face coating on the untreated piles of the Howard wharves which are 

 adjacent. This practice was ordered stopped by the Fish & Game 

 Commission, together with the Oakland Port Authorities. The life of 

 these untreated repair piles, thereafter, was limited to what might 

 have been expected in waters where Limnoria are active. The Howard 

 Company are now using only creosoted piles under their wharf struc- 

 tures. In the fender systems untreated piles are still being used. 



The findings of this Committee during the last year, pertaining to 

 bark as a protection to untreated piles do not materially alter the con- 

 clusions appearing in the last report (Plate 1, Fig. 1). 



We now have service records for Eucalyptus piles that are worthy 

 of study. From the report of the Board of State Harbor Commissioners 

 which has been given, it will be noted that the large number of Euca- 

 lyptus globulus piles driven in 1909 failed, partly by breakage and part- 

 iy from Xylotrya attack, within four years. In Pier 38 four of these 

 piles (mooring and fender) are still in place, although gone at mud line 

 from Xylotrya action. The San Francisco-Oakland Terminal Railways 

 used a large number of Eucalyptus piles in their original trestle. In 

 the stub of original trestle fctill remaining in place there are standing 

 some few, number indeterminate, whose life has approximated ten 

 years. Conditions at the S. F.-O. T. Ry. pier are much less favorable 

 to Teredo and Xylotrya than on the San Francisco side, but Limnoria 

 is apparently much less affected. 



Eucalyptus globulus piles seem from the present evidence to re- 

 sist the attack of Limnoria to a greater extent than does Douglas fir, 

 but of Teredo and Xylotrya little if any better. Any advantage which 

 this species might have in respect to borer resistance is in most cases, 

 however, negatived by mechanical failure, due to its excessive tendency 

 to split and check either in driving, or under the effects of weathering 

 or the impact of boats in subsequent service. 



Untreated piles, unprotected, still have their use in temporary 

 marine structures, but extreme care must be used in investigating 

 local conditions. The principal things to note are: (1) exposure 

 to attack (see tables of salinity for locality; note proximity of infested 

 structures) ; (2) possibility of protection by local contamination which 

 may in some cases prove an unfavorable environment for pests. No 

 sufficient knowledge is yet available as to the nature of such con- 

 taminations. The purpose for which a structure is to be used will 

 determine whether it will have outlived its usefulness prior to the 

 time of anticipated collapse. 



Untreated piles in uncontaminated salt water, known to be in- 

 fested, will withstand the attacks of Limnoria without losing their 



