84 



over and above the comparatively small increased cost necessary to secure it. Infor- 

 mative effort addressed to those responsible for the financial control of projects is 

 often highly profitable in respect to the impro^•ement of construction results. 



For the reasons cited above, substructure design must be such that it can be 

 executed under average practical conditions by the a\ailable quality of workmanship 

 and it must be simplified as far as possible. E\'en so, e\ery effort will be necessary to 

 secure the most careful workmanship, and constant attention as well as intelligent and 

 conscientious inspection will be required. 



Repair 



Reference has already been made to the fact that the life of piling can often be 

 prolonged many years by properh' repairing it from time to time. Several methods of 

 accomplishing this have been de\eloped to serve various conditions. In creosoted 

 piling, holes made by dogs, pike poles, etc., or any others of small size and regular form 

 should be plugged with creosoted plugs. Larger holes or those of irregular shape, such 

 as those in creosoted piling attacked b>' borers, ha\e been repaired bj- filling with 

 cement mortar when above low tide level or by covering the holes with layers of 

 saturated felt and sheet copper securely nailed. Yellow metal used instead of the latter 

 has been found to corrode too rapidly. When copper is used it must be thick enough 

 to allow for some surface corrosion. 



The Southern Pacific Company has successfully repaired creosoted piling by the 

 latter method, using two la\ers of saturated felt and a sheet of copper, the work being 

 done both between tides and below water, as follows : 



A supply of repair patches in the various sizes which have been found most com- 

 monly required is prepared in advance. The layers of felt and the sheet of copper are 

 stuck together with hot asphalt so that the patch can be handled as one piece, and the 

 perimeter is punched for nail holes. The pile is cleaned of barnacles and other forms of 

 sea life, and the holes to be repaired are located and measured for patches. The proper 

 sized patches are then selected and immediately applied. In this way the work is ac- 

 complished expeditiously and efficiently. Repaired piles ha\e in several instances been 

 remo\ed and the repair work done below water has been found to have been perfectly 

 carried out. 



Concrete spalling or cracking above low water can be repaired by pointing or by 

 using gunite. (See further p. 129.) If deterioration of a substructure member is 

 general a concrete shell may be cast around it. 



Removal of Breeding Grounds — Harbor Sanitation 



A borer infestation is maintained solely through the presence of exposed unpro- 

 tected wood. One pile may harbor 150,000 teredos, each capable of producing 2,000,000 

 larvae to attack other piles. The Bay is so thoroughh- seeded up that e\-ery floating 

 fragment of wood is likely to be infested to its capacity. Yet it is not uncommon for 

 structures attacked In- borers to be abandoned and left standing until they collapse, 

 large masses of the structure and clusters of piling floating awa>'. This is not only a 

 menace to navigation but pro\ides the means of spreading the infestation. Such 

 material establishes a menace equal to fire hazard. It is to the interest of every owner 

 of a marine structure to eliminate such wood as far as possible, and if property owners 

 a^•oid taking proper action themseKes, laws should and eventually will be created to 

 enforce it which may result in greater expense and restriction than if the matter had 

 been handled \'oluntarily. 



The use of unprotected timber piling should be avoided in waters which are 



