Figure 5.3 illustrates the approximate relationship between the 
cost per mile of the dike and dike height (Ralph M. Parsons Co., 1969). 
These costs include the polder and all necessary items, such as drainage 
channels and sealer. Assuming a 40-foot high dike, the approximate 
cost would be $7% million per mile of dike; the cost for each size of 
platform, based on the assumption the polder has water on three sides, 
is given in Table 5.1. Since a 40-foot high dike is somewhat higher 
than most platforms need to have adequate draft clearance, the totals 
in Table 5.1 can be considered to be on the safe side. 
Table 5.1. Estimated Costs of Polder Dike 
Platform Assumed Polder Cost of Polder Dike 
Size (ft) Size (ft) (40-f£t dike) 
300 x 300 400 x 500 $1,840,000 
400 x 1200 500 x 1400 3,400,000 
1000 x 4000 1200 x 4400 9,600,000 
As is true of all large construction projects, the costs of moving and 
placing large amounts of material to construct a polder can vary 
between wide extremes because of differences in location. Thus, any 
cost estimates for the dike and polder arrangement must be viewed as 
indicators of orders of magnitudes rather than actual values. 
Drydock. As noted in Part 2 of the report, drydocks have been 
used successfully as construction sites for floating concrete vessels. 
While feasible for this type of construction, it is doubtful that a 
full-scale platform could be built in an existing drydock because of 
limitations on width. There are very few drydocks big enough to build 
a 300-foot by 300-foot structure. According to Kohler (1970), the 
largest shipbuilding dock in the world is over a third of a mile long 
and 100 yards wide. Located in Belfast, this dock is capable of accom- 
modating ships of up to one million tons dead weight. As a practical 
alternative to using such a large dock or something similar, it seems 
best to design the modules to be more ship-like in plan -- perhaps 100 
feet by 300 feet or even 100 feet by 1,000. 
There are some noteworthy advantages resulting from fabricating 
modules in a drydock. Foremost is the ready-made work site near the 
water's edge. Also, there is ready access to the large capacity cranes 
which are standard equipment at any shipyard; but, since it is routine 
to establish complete concrete-mixing plants, including heavy-lift 
cranes, in virtually any location, it would seem best to consider the 
availability of heavy construction equipment of secondary importance. 
