The study basically confirmed the original design. When increasing the wave height to 

 34 feet rather than the original design wave of 27 feet, the section showed no tendency to 

 catastrophic failure due to a single wave, consistent with the basic design objective. 



(c) Instrumentation. There is no instrumentation set up to record physical 

 conditions at the site. 



Various instrumentation installations in the area have been unsuitable for studying 

 Rincon due to distance and type of data recorded. 



A group of level check points has been developed on the island from which to run a 

 releveling program periodically and to tie in with bench marks on shore maintained by the 

 Earth Science Laboratories of the National Oceanic and Atmospheric Administration 

 (NOAA). 



(7) Structural Performance. 



(a) Performance. Structure performing satisfactorily. Lack of recorded data 

 leaves uncertainty as to maximum condition experienced. Eyewitness evidence indicates 

 20 feet may have been the highest wave experienced. As designed, the armor would have 

 proved unstable for waves over 27 feet and overtopping would have occurred with 34-foot 

 waves. Neither of these conditions has occurred. 



Settlement during the construction period was approximately the expected 6 inches. 

 Since then there has been no change in the island elevation relative to the onshore bench 

 marks. 



A crack has developed recently in the end wall of a concrete block building on the filled 

 area at the east end of the island (causes undetermined to date). 



(b) Maintenance. Regularly scheduled inspections are made of the condition of 

 the armor both on the surface and underwater; levels are run at regular intervals, checking 

 elevations at selected points against onshore bench marks. Good results have been obtained. 



Maintenance requirements for the structure have been nominal. 



(8) Effect of Structure on Environment. 



(a) Physical. Because of considerable littoral transport along the mairdand 

 coastline in the area, it was expected that the island's size and location would keep 

 interference with littoral transport to a minimum. Aerial photos show no noticeable changes 

 in the adjacent shorelines. 



A sUght variation in bottom contours has developed, partly due to construction 

 operations, and partly to the island's interference with the natural easterly channel flow. 



(b) Biota. Assistance (in the form of physical facilities and complete 

 cooperation) has been provided by the owner to Moorpark College, Moorpark, California for 

 a study of marine life in the area. 



A recent study (Keith and Skjei, 1974) was undertaken to determine the changes 

 brought on by the island construction in the environment for the marine biota in the area. 

 The results indicate "the development of a mature and balanced reef out of an area which 



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