Exposure Racks 



All of the test specimens were mounted on racks as shown in Figure 

 2. Each of the panels was held in place by four molded, grooved, poly- 

 ethylene insulators and were separated from each other by 1 inch. The 

 center dividers and end plates were titanium alloy 75-A. The tie rods 

 through the insulators were nickel-copper alloy 400 fastened with nuts 

 and washers of the same composition. Poly (vinyl chloride) (PVC) washers 

 were used between the metal washers and the end plates. The rope speci- 

 mens were wrapped around the racks in such a way that the center sections 

 of the ropes would be embedded in the mud and the eye-splices would be 

 held out of the mud at the tops of the titanium racks. Four such racks 

 were prepared in replicate. 



Anaerobic Test Site 



The Port Hueneme harbor anaerobic test site was selected during the 

 preliminary stages of this investigation. The harbor bottom was known 

 to be stagnant at the site which was near the mouth of a small drainage 

 ditch and underneath the ship-berthing area. Debris from the drainage 

 ditch and wastes from the ships contributed to the development of an 

 anaerobic harbor bottom. 



Stringent regulations on the discharge of wastes from shore and 

 from ships have resulted in a decrease in the quantities of organic 

 matter in the Port Hueneme harbor. In consequence, the test site was 

 not quite as anaerobic as had been expected. Grab samples of mud from 

 the test site area still had the odor of hydrogen sulfide, but the water 

 a short distance from the bottom contained sufficient oxygen to support 

 a scant growth of fouling and burrowing organisms (Figures 3 and 4) . 



Ocean or harbor bottoms in anaerobic areas are typically covered by 

 thick layers of soft mud. It was anticipated that when the sample racks 

 were lowered, they would sink into the mud layer, but they did not 

 because this mud layer was not as thick as expected. As a result, 

 divers had to shovel harbor bottom sediments and partially cover the 

 specimen racks with the sand, gravel, and other bottom sediments at the 

 site. By the end of the 2-1/2-year exposure period, most of the cover 

 had apparently been removed from the specimen racks, because they were 

 covered by a scant growth of fouling organisms. The fouling organisms 

 were not of the mud-burrowing type; they would ordinarily have been 

 unable to reach the sample rack had it been completely buried in the 

 bottom sediments. 



