Site shutdown and restoration. 



Activity sequence 



on 



Completion of exploratory drilling, removal of production facilities, 

 backfilling of pipeline ditches, and spill cleanup usually signal initi 

 ation of the shutdown and restoration phase. Permanent structures, 

 equipment, concrete foundations, pipes, surface flowlines and supply 

 lines, well casings, drilling mud, and other artifacts of oil producti. 

 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 for petroleum companies to fill access canals. The canals 

 are used for a long period of time, as long as the wells are productive 

 or as long as the field is active. During this period, the canal banks 

 erode and spoil piles compact and subside. Thus there is not enough fill 

 material from the old excavation to refill the canal. In most instances 

 fill material would have to be barged to the site, which is often eco- 

 nomically unfeasible. Therefore many canals are simply abandoned, though 

 in areas where significant canal water movement posed problems, canal 

 plugs have sometimes been constructed. 



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, heavy construction machinery, barges, and/or marsh 

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

 and site preparation. 



2. Primary ecological alterations 



2.1 Temporary loss of producer biomass along flowlines, vegetated levees, 

 and pad sites 



2.2 Loss. of consumer biomass in access canals and pipeline canals due to 

 refilling procedures 



2.3 Increase in producer biomass on formerly barren sites due to revege- 

 tation 



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