flooded. Riprap protection for the dike is to be provided and the basin 

 equipped with wellpoints or deep wells to dewater the sandy soil in the 

 area. 



After the first six units are cast to a minimum height of about 50 

 feet, the basin is flooded at a controlled rate and enough of the dike 

 removed to provide an opening wide enough for each unit to be floated 

 out one at a time. The dike is then rebuilt, the basin dewatered and 

 the next cycle of six units constructed. Since concrete placing is 

 expected to be easiest at this location, as much casting as possible is 

 planned under the restriction imposed by available channel depths, to the 

 outfitting pier. 



Because of the large concrete volumes and the need for a continuous 

 supply (about 1,600 cubic yards per day at both the precasting site and 

 outfitting site), a separate concrete plant was planned for each site 

 with distribution by trucks and buckets, perhaps requiring multiple 

 shifts. 



Since adequate water depths occur some distance from shore at the 

 outfitting pier site, and probably in an area without much natural pro- 

 tection, an access trestle, 2,000 feet long and 30 feet wide for two-lane 

 access with a 600- by 40-foot working area at the offshore end is planned. 

 The cost of this facility has been written off against the project, but 

 circumstances may suggest a permanent structure for recreation or other 

 use. 



Because of the size of the units (215 by 246 feet) , the material 

 handling reach requires equipping each unit with a tower crane during 

 construction. 



Since the boxes are designed with an neaily uniform cross section, 

 slip forms appear to provide the quickest and most economical method of 

 construction. Generally, units under construction will not float level, 

 and surveying control will require special procedures. Such procedures 

 have been implemented on similar work. 



A template rig may be used to serve as a temporary working platform 

 for positioning and alining the first unit at the final site. Once the 

 first unit is set, screeding equipment erected and construction started, 

 the extra platform is no longer needed. 



As estimated, positioning the first unit will take longer than subse- 

 quent units. The precise location is not critical but alinement must be 

 close to final design alinement so that the planned protection is obtained. 

 The first unit serves as a point of reference when in place so that 

 following units can be positioned more easily and rapidly. 



Although the materials within the boxes seem secondary, the quantities 

 are large enough to justify consideration. The boxes would be sunk with 



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