2.5 Introduction of toxic materials into the site's water and soil 

 systems 



2.6 Displacement of sensitive wildlife species from adjacent areas 

 due to treatment processes and constant human activity 



2.7 Alteration of water flows in localized areas 

 Attribute alterations 



Conversion of a well to production status creates few additional 

 site alterations. In the case of a leveed pad, all activities occur 

 near the wellhead and central pad area. Operation consists 

 primarily of periodic maintenance and inspection visits. Equipment 

 repair may occasionally require limited activity on the pad. Out- 

 lying portions of the pad revegetate following reduced activity 

 levels. If drilling was conducted from a special barge, the capped 

 wellhead is enclosed by a small elevated platform and the barge is 

 subsequently removed. Construction of the platform and barge 

 removal cause localized increases in suspended sediments. The 

 effects, however, are \/ery temporary and restricted in scope. 

 Consequently, further considerations will not address the very 

 small-scale alterations generated at the existing wellhead location, 

 but will concentrate primarily on the ecological alterations 

 uniquely associated with the construction and operation of a central 

 treatment complex in unmodified marsh. 



Attribute alterations are similar in scope but smaller in scale than 

 for well site preparation. Site preparation for the treatment com- 

 plex removes all biotic components within the construction 

 boundaries through dredging, spoiling, digging, filling, and pile- 

 driving activities. A direct loss of approximately 0.4 ha (1 acre) 

 of sustaining habitat results for primary and secondary consumers. 

 Food and cover losses are particularly significant for small 

 mammals, local insect populations, and some aquatic invertebrates as 

 proportionally larger portions of their resource base are removed 

 or altered. The carrying capacity of the marsh for supporting 

 secondary consumers such as the predatory mammals and birds, water- 

 fowl, alligator, and estuarine fish is certainly reduced by such 

 habitat alterations. The significance of such an isolated loss at 

 the. ecosystem level of consideration is unknown, however. 



Reworking the marsh substrate to build ring levees and spoil pads, 

 as well as placing pilings and other support structures, causes 

 increased levels of suspended sediments, dissolved nutrients, water 

 turbidity, and biological oxygen demand at the construction site. 

 Subsequent weathering and erosion of barren spoil deposits and 

 routine maintenance traffic through the access canals sustain these 



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