Dredged well site operation . 



1. Activity sequence 



Drilling and auxiliary equipment and supplies are transported and stored 

 on barges. A specialized barge is employed for drilling. Its ballast 

 tanks are flooded, the barge settles to the bottom, and piles are driven 

 to anchor it firmly in place. Drilling activities require one to three 

 months. Test results indicate whether the well should be put into pro- 

 duction or capped and shut down. Impacts are primarily due to noise and 

 activity associated with traffic and drilling, and leaks or spills of 

 chemicals, mud, or petroleum materials. 



2. Primary ecological alterations 



2.1 Introduction of toxic materials to water and soil systems 



2.2 Extended displacement of wildlife from entire area adjacent to canal 

 and well site 



Attribute alterations 



During this phase of operations (one to three months), the water and soil 

 systems are exposed to a wide variety of pollutants from drilling mud, 

 sump discharge, and vehicle and equipment waste (exhausts, oil, grease, 

 gasoline). The kinds and amounts of these materials, and hence their 

 effects, are site specific. In general, these materials are restricted 

 to the dredged wellsite and canal and only in unusual circumstances, such 

 as storms or blowouts, are they transmitted to surrounding unmodified 

 marsh. In the latter case, however, they may occur in concentrations 

 that are lethal to aquatic vertebrates and invertebrates, or they are 

 irritating to nearly all consumers. This may result in displacement of 

 consumers for periods of weeks to years, depending on cleanup efforts, 

 natural degradation of materials, and vegetation alteration. 



Wellsite operation involves continuous, noisy, and long-term disruption 

 of sensitive wildlife species. This factor should be considered during 

 this phase of oil and gas operations since it extends the effects of the 

 project beyond the boundaries of the immediate site. If the well is pro- 

 ductive, noise and human presence may be daily occurences at the site, 

 though levels of activity are not as concentrated as during drilling. 



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