30 



Avon 



Associated Oil Co. 



Bay Point 



Pacific Coast Shipbuilding Co. 

 Coos Bay Lumber Co. 



MALL;\RD 



San Francisco-Sacramento Railroad ferry. 



Chipps 



San Francisco-Sacramento Railroad ferry. 



DUTTON 



San F"rancisco-Sacramento Railroad trestle and drawbridge. 



Pittsburg 



Small docks. 



Antioch 



Muncipal dock. 



A. T. &S. F. R. R. dock. 



Returning to construction progress in the Bay region, in 1919 a change in the 

 Government pierhead line at Oakland caused the removal of the Long Wharf exten- 

 sion, originally built in the years 1869 to 1871 and rebuilt in the years 1890 to 1900 

 with creosoted piling. Most of this piling, totalling a large amount, as has already 

 been stated, was found in excellent condition at the date of its removal. 



In 1921 an extensive program of piling inspection by diver, and of repair work, 

 was completed on the San Francisco wharves of the Board of State Harbor Com- 

 missioners. This investigation disclosed the remarkable fact that eighty per cent of 

 the pile flaws attacked by Limnoria had been caused by the careless driving of pile 

 dogs or pike poles in sections falling below the water level, the holes not having been 

 plugged after the dogs were pulled; about fifteen per cent were in checks developed 

 during or after driving, and the balance were from miscellaneous defects. 



The year 1922 saw the completion of the seawall around the southern portion of 

 the San Francisco front from Market Street to China Basin, enclosing the area where 

 wharA'es had existed since the early 50's. The old Mission Street wharf No. 1 had, 

 with reconstruction and relocation, been in service from 1853 to 1909, or fifty -six 

 years; Howard Street wharf No. 1, built in 1865, was removed in 1914 after forty- 

 nine years of service; the Pacific Mail wharf, built in 1866, was removed in 1907 after 

 forty-one years of service. During the period from 1904 to 1922 in which the south 

 section of the wall was built, there had also been constructed seventeen new piers 

 projecting from the new wall, replacing practically an equal number of old wharves, 

 such as the three mentioned above, which had been built to conform to the old water- 

 front plan. 



In 1922 work was started on o e of the largest of San Francisco harbor projects, 

 the China Basin Terminal. The substructure on the water side consists of a series of 

 rectangular concrete piers 7.5 feet thick, 20 feet wide and from 54 to 57 feet deep. 

 They are connected at the top by pre-cast, curved, reinforced concrete arch slabs to 

 form the wharf floor support, and on the inshore side by similar slabs to form a re- 

 taining wall for holding back the foundation fill. The piers were constructed on shore 

 as reinforced concrete caissons, after which the ends were sealed and the caissons 

 floated to the site. They were then sunk into position bearing on hardpan and fifteen 



