imdoubtedly a strong factor in the contractor's decision to use a floating 

 plant. If the causeway had been included in the original bid package the 

 work trestle approach would have been a more attractive alternate. Such 

 a method greatly reduces both investment and operating costs of the required 

 construction plant, and greatly reduces rehandling of materials. Such 

 savings, of course, are balanced to some degree by the expense of building 

 the required temporary trestles. 



The construction methods used for the island would in general be 

 equally appropriate today, with the minor exception of survey control 

 methods. Laser beams for position lines and an electronic positioning 

 system for spot location would probably be used in place of the wood dol- 

 phins and survey tower. 



As mentioned in the discussion of seismic considerations, compaction 

 of the submerged core fill would probably be an additional contract 

 requirement. Submerged vibratory equipment of some type would be the most 

 economical method of fulfilling such a requirement. 



13. Island and Causeway Maintenance 



Maintenance requirements for the basic island structure have been 

 nominal to date. Assuming that the wave predictions were accurate and the 

 revetment design exact, some wave damage to the west face armor rock should 

 have occurred. However, the lack of damage to the west face armor to date 

 is insufficient proof that the wave predictions or design are overly 

 conservative. 



The east wings were not designed to be stable against waves much 

 higher than 12 feet. No direct measurement of the degree of wave attenua- 

 tion was made, but design assumptions based on qualitative data from the 

 model studies indicated damage could be expected from westerly waves about 

 20 feet high, which would be somewhat attenuated before they reached the 

 east wings. Again, the lack of wave damage to armor rock on the easterly 

 wings is not an adequate criterion for establishing maximum wave heights 

 at the island to date, since the individual weights of armor rock actually 

 placed were considerably higher than the specified minimum weights used for 

 the design. 



Based on discussions with operating personnel, it is believed that 

 maximum wave heights to date are about 20 feet. Topsoil in some of the 

 concrete planter boxes on to^ of the east wing has been lost, and one of 

 these boxes has a 0.5-inch crack, indicating some minor shifting of cap 

 rock on the southeast wing. 



Causeway maintenance has been slight. The most troublesome item has 

 been painting of the steel on the abutment span. The causeway profile was 

 designed to keep the deck structure clear of wave crests, but keeping the 

 shore end high enough to also avoid most of the spray from the abutment 

 fill would have been desirable. 



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