101 



feet and they were C()\ereil for an average distance of M feet, l)eing the distance from 

 a point abo\e high water hne to 10 feet below the mud hne when dri\en. The bark was 

 first remo\ecl from the portion of the pile to be covered, then a coat of P. & B. pile 

 paint was applied. Oxer this, P. iS: B. pile covering was placed and o\er the pile coxer- 

 ing a hot coat of "Floatine" (an asphalt base paint), then V2 in. x 2 in. redwood bat- 

 tens and finally another hot coat of "Floatine." The protection was aj^plied by the 

 Northwestern Pacific Company at a cost of 62 cents per lineal foot of pile covered. 

 There was an additional cost of vS5.9,S per pile for taking the piles out of the water for 

 treatment and rolling them back afterwards. 



This method of protection was adopted for this structure lor the lollowing reasons: 

 The estimated cost per pile was materially less than the estimated cost of creosoted 

 piles; the old trestle of untreated piles had been in place at this jioiiit for ,^3 years and 

 so far as ascertainable the marine borers had not molested it prior to the last two 

 years, and it was believed that with the return of a normal winter rainfall, the salinity 

 of the water in the stream would be sufficiently reduced to exterminate borers. It 

 was belie\ed that it was reasonable to assume that conditions existing for 31 years 

 would be restored before the temporary protection afforded by this method of treat- 

 ment had deteriorated to such an extent as to permit damage by the liorers. I'roni 

 experience with piles protected in the same manner and dii\en under whar\es at 

 Tiburon by the same company about twelve years before, it was belie\ed that this 

 treatment could l;e counted upon to protect the piles for from fi\e to eight years. 

 There is but little driftwood or wa\'e action in the stream to cause abrasion. Moreover, 

 because of the difficulty of satisfactorily bracing a timber trestle on account of the 

 depth of water and the increasing wheel loads, it was presumed that this structure 

 would be rebuilt with concrete and steel within a period lor which the method of 

 treatment adopted might reasonably be expected to furnish protection against the 

 marine borers in the e\'ent the>- should remain in this stream permanenth'. 



In 1921 the Southern Pacific Compan\- dro\e 107 piles protected by this process 

 in the Georgia Street wharf at Vallejo, for experimental purposes. These piles were 

 all in actual service under ideal conditions for their use. In about 3 years the battens 

 began swelling away from the pile and borer attack started. The piles are still in 

 service (1925), the borer action being retarded by the surface protection, but it does 

 not appear likely that a life exceeding about 5 years will be secured. 



Fig. 38. Bulging battens on piling protected by Moran and Paraffine processes at Georgia St. 

 wharf, Vallejo, after three years' service. [S. P. Co. Photo.) 



