During an engineering survey the detailed bottom profile, sub- 

 bottom stratigraphy, currents, and soils, along with items of special 

 concern such as faults, reefs, rock outcrops, and sand waves are investi- 

 gated. All of these parameters must be known to properly design the 

 pipeline so that installation will go smoothly and the pipeline will 

 operate safely and successfully throughout its intended lifetime. 



Proceeding directly to an engineering survey of the chosen corridor 

 essentially removes the possibility of reducing the macro-level environ- 

 mental impacts of a pipeline, because they can only be eliminated 

 through siting the pipeline in an environmentally acceptable corridor. 



Landfall to Destination : An oil pipeline does not require a wide 

 corridor of land once it comes ashore (nationwide, however, pipelines 

 may be the most land-consuming petroleum activity). The oil pipeline 

 will require a minimum right-of-way between 50 to 100 feet, some of 

 which may be purchased "in fee"; use of other rights-of-way may be 

 obtained by the pipeline company. Gas pipelines require a similar 

 right-of-way. The shore destination— a partial treatment facility or 

 gas processing plant--would be located inland from the landfall site. 



Pumping stations are usually required near the landfall site for 

 pipelines transporting oil any appreciable distance. The station could 

 require 40 acres of land and could consist of an office, storage surge 

 tanks, and a pump station. An onshore transfer terminal (for barge 

 transshipment) would require a waterfront location of about 60 acres, 

 with a minimum 35 foot water depth by the frontage land. Another 

 alternative would be to have the oil repiped offshore to a marine terminal 

 where it would be transshipped by tankers [26]. 



Construction/Installation 



Three methods are used for laying offshore pipelines: 



1. The method used for most pipelines and for all large diameter 

 pipelines is to weld together 40-foot pipe 



sections on board a lay barge and continuously lower them 

 over the stern of the barge via a "stringer" to the 

 ocean bottom. As new pipe sections are added, the barge 

 winches itself forward using a sophisticated multi- 

 anchor system. 



2. A second method, the reel method, is used for laying 

 small diameter pipelines; traditionally 12 inches or 

 less, but now up to 24 inches. The pipe is welded together 

 onshore, wound onto a large spool, and then later unwound 

 for laying of the pipe. This method is often used for 

 flow lines between platforms. 



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