Subproject: Groundwater Supply (SP-9) 



Disturbing Activity: Groundwater withdrawal 



Total water usage depends largely on the production rate of a yard 

 and whether the yard incorporates steel processing into its operations. 

 At a production rate of two to four platforms a year, a yard could require 

 1,250,000 gallons of water per day if a steel processing or pipe rolling 

 mill were in operation [7]. The Brown and Root plant proposed for Cape 

 Charles, Virginia, which does not incorporate a mill, would use 100,000 

 gallons of water a day at a production rate of nine platforms per year [14], 



Subproject: Stormwater Systems (SP-12) 



Disturbing Activity: Stormwater conveyance 



Little of a platform fabrication yard is paved; therefore, a 

 large facility would have several hundred acres of bare dirt or 

 gravel surface. For an assumed annual precipitation between 40 

 and 60 inches, 200 acres might produce 40 to 65 million gallons of 

 runoff per year to be collected and treated by the stormwater runoff 

 system. Runoff turbidity may be reduced through the use of retention 

 basins or settling ponds. The presence of antifouling compounds and 

 other toxic contaminants in the yard may require extensive recondi- 

 tioning of stormwater before release to coastal waters. 



3.6 PIPE-COATING YARDS 



3.6.1 Profile 



Unless an oil or gas field is far offshore or the yields is low, a 

 pipeline system is usually preferred over tanker transport for economic 

 reasons and because the spill potential is lower. Where pipe is being 

 laid from an offshore field to landfall, a pipe-coating yard will be 

 located at a nearby onshore site. A pipe-coating yard prepares standard 

 40-foot sections of pipe, usually between 14 and 44 inches in diameter, 

 for installation on the sea floor at depths up to 600 feet or more. 



Offshore pipe sections require two outer coatings: one to protect the 

 steel pipe from the corrosive effects of seawater, and another to add suf- 

 ficient weight to overcome the tendency of the pipeline to float when 

 filled with buoyant oil and gas. After coating, a 40-foot section of the 

 largest-diameter pipe may weight up to 40 tons [7]. Coating on the inside 

 surface of the pipe, which is needed when the oil or gas has a high sulfur 

 content, will normally be applied at the pipe mill and not at the pipe- 

 coating yard. Differing diameter pipe can normally be handled at a 

 single yard without delay. 



Normally, pipe sections are sent by rail or ship from a steel mill 

 to the pipe-coating yard where they are coated. The prepared sections are 



44 



