components. Gas and oil transportation pipelines, on the other 

 hand, modify important ecosystem attributes. Key alterations 

 involve: (1) the immediate large-scale removal of existing plant 

 assemblages and habitat components necessary to local consumer 

 groups; (2) the long-term substitution of new plant cover types and 

 community structure within, and sometimes adjacent to, the pipeline 

 corridor (with resulting community conditions that may differ from 

 initial conditions, leading to subsequent changes in consumer 

 species composition and population levels); (3) alterations of the 

 existing surface-water hydrology; and (4) short-term displacement of 

 sensitive wildlife during construction and operation phases. 



Placement and operation of production facilities. 

 1. Activity sequence 



Production occurs both at the wellsite and at a central treatment 

 complex. Normally at a wellsite only slight structural modifica- 

 tions of the existing pad are necessary to convert the well to 

 production status. Placement of gathering flowlines from the well 

 to the treatment facility requires activities as described for the 

 installation and maintenance of lines; these include line survey, 

 limited vegetation clearing, line installation and burial, and 

 necessary site restoration. Construction of a processing complex 

 and pipeline pumping stations follow the same basic activity sequence 

 as that described for wellsite preparation, except that the placement 

 of treatment, pumping, and storage facilities follows pad 

 completion. Within the pad, foundations are dug and concrete is 

 poured to anchor or support structures and equipment. Brine-disposal 

 lines to the disposal well are installed although brine-storage pits 

 occasionally may be dug, if necessary. Routine operation, mainte- 

 nance, and repair of treatment, pumping, and storage equipment are 

 conducted within the confines of the pad site. Processing wastes 

 are stored within the complex area, disposed of via flowlines, or 

 transported off site immediately. Typical areal extent of a produc- 

 tion facility is approximately 0.4 ha (1 acre). 



2. Primary ecological alterations 



2.1 Creation of an unvegetated production or pumping station site 

 typically 0.4 ha (1 acre) or less in area 



2.2 Displacement of consumer groups within the facility site 



2.3 Loss of soil structure due to movement of heavy machinery and 

 construction activities 



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