Some differences were due to technological developments. Whereas most 

 marshland pipelines were formerly laid by the flotation method, the development 

 of equipment and techniques led to use of the "push" method in all but the 

 softest marsh sediments. Development of high-capacity pumps allowed pipelines 

 to be "jetted" into soft sediments that formerly were excavated by dredge. 



The methods observed presented a range of techniques indicative of the 

 variety of industry practices. Access to sites included land roadways, marine 

 (dredged) sites, and a combination whereby vehicles were moved by barge to road- 

 ways built on marshes. One refuge offered a pipeline corridor leading across 

 the land, with all pipelines within a lateral distance of a few hundred meters. 

 Several types of pipeline-laying methods were used, including flotation, pushing, 

 jetting, and the typical upland pipeline "spread." Marsh buggies on refuges 

 in Texas tended to have large rubber tires; in Louisiana, nearly all marsh bug- 

 gies were tracked vehicles. 



Muds and drilling fluids were confined, sometimes in steel containers, 

 barges, or earthen levees. Drillsites themselves consisted of shell pads, 

 leveed marsh-floor locations, older elevated marsh locations, and marine loca- 

 tions. Waterflow and water circulation structures varied: small and large 

 culverts, low wooden bridges, or no structures at all were at different sites. 

 Various restorative measures ranged from none at all to complete restoration 

 of natural contours and vegetation. 



Numerous other practices were present in different forms, even within a 

 single refuge. These included: canal orientation; herbicide use; revegetation 

 techniques; orientation of overland access routes; use of former sites; methods 

 of laying pipeline across canals; sedimentation control levees; bulkheading 

 types; placement of tank batteries; seismic survey methods; dredge types; spoil 

 placement; camouflage; site placement criteria; slant drilling; and secondary 

 retaining levees. 



Miscellaneous Differences 



The refuges differed with respect to size, age, and extent of oil and gas 

 activities. There was also variety in the accessibility of sites, records, 

 and personal experience of the refuge managers with oil and gas activities on 

 a particular refuge. 



REFUGES SELECTED FOR STUDY 



Based on the selection criteria discussed above, six wildlife refuges were 

 chosen for intensive study. They were: 



1. Aransas National Wildlife Refuge - Lying near the center of the Texas 



Coastal Bend, and encompassing 22,300 ha in parts of Aransas, Refugio, and 



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