40 



is a highly specialized product, and like all such products, its adapta- 

 tion to a special purpose involves greater care in protecting it against 

 other conditions. But the very greatly increased resistance ayninxt 

 marine borers given to wooden piling by good creosote treatment is cer- 

 tainly worth the price which must be paid for it in protecting it from 

 mechanical damage. 



It seems justified again to emphasize the statement of last year 

 that a great need of the San Francisco Bay region is a creosoting plant 

 in this vicinity. A part of the remarkable record shown by the Long 

 Wharf piling was unquestionably due to the fact that it was possible 

 to creosote it in the Company's own plant close to the point where the 

 piling was to be installed, thus minimizing handling damage- The 

 rafting, storage and repeated handling, almost universally accompanied 

 by dogging, which is incident to obtaining piling at a distance, makes 

 damage from such sources almost impossible to prevent; and this is 

 the position occupied by all users of creosoted piling in the Bay region, 

 except the Southern Pacific Company, to whom the Long Wharf be- 

 longed. It is not surprising, therefore, that the Harbor Commission 

 found 80 per cent of all damages occasioned by dogging. 



In the case of creosoted piling, as in that of other forms of piling, 

 the Committee feels that the volume of service records so far accu- 

 mulated does not represent a sufficient proportion of the whole body of 

 structures in this territory to warrant the stating of an average life. 

 A conclusion respecting the range of life which may reasonably be ex- 

 pected from creosoted Douglas fir piling in this region under c.rifttiuf/ 

 conditions may,, however, be legitimately drawn, and will be found in 

 the summary at the end of this section of the report, for this as for 

 other types of piling. 



Reinforced Concrete Cylinders 



The information contained in the 1921 report regarding this type 

 of construction has been amplified by a detailed record of repairs to 

 existing structures on the San Francisco Waterfront (Plate 7, Fig. 2). 

 The defects noted appear to be the result of insufficient and improper 

 tamping and of negligence in cleaning construction joints where con- 

 creting was discontinued (Plate 8, Fig. 1). In both cases the negli- 

 gence was aggravated by the use of excessively wet consistencies of con- 

 crete which have been conclusively proven to produce inferior con- 

 crete, and which, although once considered good practice, are no longer 

 permitted in the best modern practice. Owing to the massiveness of 

 the columns, no defects have developed to date which materially af- 

 fect the structural stability of the piers. Defective construction joints 

 have been repaired by pointing and grouting, and inferior concrete 

 by encasing the cylinder in a shell of dense concrete. The cylinders 

 of the U. S. Army Transport Docks at Fort Mason and of Piers 30-32 



