protect previously undistrubed habitats from construction and development 

 activities. Corridors should be planned to avoid vital areas such as 

 fish spawning areas and wildlife breeding and nesting areas. Sensitive 

 habitats such as dunes, wetlands and others should be avoided. 



A rough estimate of the width of land disturbed by pipelines laid 

 through wetlands or on land would be 50 to 60 feet. On dry land, a swatch 

 of perhaps 50 feet would need to be maintained free of trees and large 

 shrubs to permit maintenance vehicle access and surveillance for leakage 

 [107]. 



4.11.3 Design 



The design of transmission lines does not hold a high potential for 

 reducing environmental disturbances. Nevertheless, a few design features 

 are worthy of mention. 



Transmission line corridors should be designed to accommodate an 

 additional load to limit further construction in previously undisturbed 

 areas and to avoid bisecting fish and wildlife habitats. Oil and gas 

 pipelines should use the largest diameter pipe that is economically 

 feasible to allow future oil and gas flows to be added without new 

 construction. 



Joints in sewer lines should be tight and should be monitored 

 frequently. Couplings that will reduce groundwater infiltration and 

 sewage escapement should be chosen. 



In unpopulated areas, power and telephone lines should be left above 

 ground to allow quick repairs and to avoid trenching. Pipelines and water 

 and sewer lines should have periodic pressure monitoring stations to 

 facilitate location and repair of troubles. 



The pipeline should nave leak or blowout preventives to shut off 

 sections of the pipeline with pressure drops in the line. They should 

 avoid seismic areas. When evaluating impact, it must be realized that 

 cross country motor vehicles, bicycles, horseback riding, and other types 

 of human disturbance may occur along corridors, particularly near urban 

 areas. 



4.11.4 Construction 



There are four general methods used in laying onshore pipelines. The 

 first of these is the dry land method. With this method a right-of-way is 

 clea'red of all vegetation, a ditch is dug, and the pipe is welded, lowered 

 into the ditch and buried in place. Trenching involves from one to several 

 pieces of heavy equipment, some of it very specialized. One type designed 

 for the sole purpose of digging trenches consists of a large wheel with 



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