thousands of waterfowl; contaminate shellfish; kill fish, crab, and 

 bivalve larvae; foul bottom sediments; and kill emergent grasses. 

 Cleanup methodologies determine site alterations that occur and 

 whether subsequent biotic changes are temporary or long term. For 

 example, spills and cleanup procedures restricted to aquatic areas 

 would have only minimal effects on higher vegetated marsh sites. 

 Karsh buggies and other surface vehicles would not be required; 

 cleanup processes could be accomplished by outboard and/or airboats. 



Potential alterations of importance to the ecosystem pertain to 

 changes in land elevations as a result of emergency earthworks or 

 the vehicular traffic required to contain or divert an extensive 

 spill. Subsequent alterations in water circulation patterns can 

 result. 



Site shutdown and restoration. 



1. Activity sequence 



Completion of exploratory drilling, removal of production facili- 

 ties, backfilling of pipeline ditches, and spill cleanup usually 

 signal initiation of the shutdown and restoration phase. Permanent 

 structures, euqipment, concrete foundations, pipes, surface flowlines 

 and supply lines, well casings, drilling mud, and other artifacts of 

 oil production are removed if they possess salvage or reuse value. 

 Otherwise, only as much attention is paid to restoration procedures 

 as is required by Federal and state regulations, lease stipulations, 

 and general company policy. Typically, restoration includes removal 

 and/or burial of toxic substances, refilling of all pits, knocking 

 down or breaking earthen levees, leveling the site, and plugging or 

 filling ditches. It is unusual to fill access canals. They are 

 used as long as the wells are productive or the field is active, 

 which may last several decades. During this period, the canal banks 

 erode and widen, and spoil piles compact and subside. There is not 

 enough fill material from the old excavation and maintenance spoil 

 to refill the canal. In most instances, fill material would have to 

 be barged to the site; this is often economically unfeasible. Many 

 canals are simply abandoned. However, in areas where significant 

 canal water movement has posed problems, canal plugs or wiers have 

 been constructed to control water movement. Natural processes are 

 typically relied upon to reestablish vegetative ground cover. Even 

 though boards may be removed from well pads and leveed roads, the 

 road/pad foundation is usually left intact. If major earthwork is 

 required, then heavy construction machinery, barges, and/or marsh 

 buggies are employed in a manner similar to that described for site 

 access and wellsite preparation. 



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