100 



DF RO DF RO 



NB WP 



Figure 13. Mean annual wood-loss caused by marine woodborers from 1983-1985 in Douglas Fir and Red Oak 

 timbers in the vicinity of the Millstone Nuclear Power Station. Estimates are based on the weight of five, 

 one inch sections from each timber. 



Radiographic estimates were used to describe wood-loss from chemically treated timbers. These data 

 indicated that wood-loss was greatly reduced in treated woods relative to untreated types (Fig. 14). Only 

 the cut surfaces of these timbers, which exposed areas with no chemical treatment, were su.sceptible to 

 recruitment of woodborers. However, shipworms were able to penetrate some areas of CCA treated wood 

 after they had settled and metamorphosed in untreated grains exposed by the cut surfaces. 



Data concerning wood-loss from timbers exposed for more than one year indicated that wood-loss 

 can more than double during the second year of exposure (Table 9). Generally, Douglas Fir timbers were 

 totally degraded by woodborers after two years, while three years were required for Red Oak timbers to 

 reach 70% wood-loss. At EF, wood-loss of untreated timbers was considerably greater, and neither 



34 



