percent of the yard area is used for welding large tubular steel jackets; 

 fabrication work areas are adjacent to bulkheaded shorelines, except 

 where a large dry dock (graving dock) is installed for final assembly of 

 the largest self-floating jackets. The remaining 40 percent of the yard 

 area is used for: storage of steel plate and structural sections which 

 are cut, rolled, bent, and welded into prefabricated partial units; 

 parking lots and administrative buildings; the welding and machine 

 shops; and the large hangar- type deck-fabrication buildings. Figure 34 

 shows the site plan for the proposed platform-fabrication yard at Cape 

 Charles in Northampton County, Virginia. 



Site Requirements 



The site requirements for a fabrication yard include the availability 

 of a skilled labor pool, access to established transportation networks, 

 access to high voltage power, a large flat site with adjacent deepwater 

 channels, and a sheltered harbor. 



The required length of the wharf depends on the number and size of 

 the platforms (steel) being constructed at any one time. Since the 

 jacket is constructed perpendicular to the wharf, the length of the 

 wharf is determined by the bass height of the platform and the number of 

 platforms lined up at the waterfront [26]. 



The required water depth at dockside and in the channel varies with 

 the type of platform being constructed. For fixed-pile platforms, a 

 depth from 15 to 30 feet is normally required. For gravity platforms, 

 particularly cement gravity platforms, much deeper water is required. 

 Once the concrete base is completed in dry dock, the base is floated and 

 moved away from dockside to depths of from 240 to 300 feet. This deepwater 

 site must be sheltered and within a few hundred yards of the fabrication 

 yard. 



The smallest facility producing platforms is 50 acres, but larger 

 yards require between 200 to 1,000 acres, with 300 acres the average. 

 Some yards are considerably larger. Brown and Root's proposed Virginia 

 site is 980 acres, of their total land holding in the area of 2,000 

 acres. The availability of the land can have important effects on the 

 size of the yard, initially as well as later on when expansion is con- 

 sidered. If the land at the chosen site is abundant and inexpensive, 

 the sponsor will likely option or purchase a larger parcel than if the 

 availability or price was restrictive [26]. 



For steel platforms the channel width should be up to five times 

 the beam of the largest barge to be towed from the fabrication yard. 

 The average beam of such barges is 60 feet; therefore, the channel width 

 is usually 300 feet. Because of the difficulties involved in towing 

 gravity platforms (such as clearance requirements, weight and height). 



152 



