chain, persistence, and presence of biota on the site; processing 

 and pumping activities preclude the presence of plants and animals 

 on the site. The effects of chemical residuals on site restoration 

 is treated in a separate section of this discussion. The recupera- 

 tive abilities of the soil's micro- and macrobiota, as well as more 

 complex flora, from petrochemical discharges are not well understood. 

 Pumping stations and processing complexes are more or less permanent 

 facilities which effectively remove portions of the community from 

 long-term production. 



4. Key attribute alteration 



The key attribute alterations involve primary and secondary effects. 

 The primary effect is the direct long-term removal of plant assem- 

 blages and directly dependent consumer groups within the production 

 site. The secondary effect is the associated long-term gradual 

 changes in nearby biota that result from subtle, microenvironmental 

 alterations of soil structure, surface water hydrology, soil toxicity, 

 partial vegetation removal, and disturbance factors. Community 

 response to such secondary alterations is expressed by the different 

 plant assemblages which develop through competition under new abi- 

 otic conditions. The species compositions and population levels of 

 the consumer groups may or may not respond to secondary habitat 

 alterations. Response is a function of the areal extent of the 

 change, the size of the consumer's resource base, and the sensitiv- 

 ity of the consumer to altered habitat conditions. Sensitive wild- 

 life species may abandon otherwise favorable habitats because of 

 operational and vehicle-associated disturbances. 



Spills and cleanup. 

 1. Activity sequence 



Accidental discharge of oil, gas, field brine or other substance 

 occurs as a result of equipment failure, improper equipment opera- 

 tion, or human error. Built-in safety mechanisms, if present, are 

 activated automatically to limit the quantity of discharge. Field 

 personnel, once aware of the spill or leak, immediately initiate 

 procedures to confine discharges to the smallest possible area. 

 Containment berms or levees are erected to prevent further liquid 

 spre-ading, or shallow ditches are excavated to intercept, channel, 

 and concentrate the effluent into collection sites. Dozers, 

 graders, and backhoes are used for such earthwork. Straw or hay is 

 used to adsorb smaller, less accessible quantities that vacuum 

 trucks cannot remove. Vegetation coated with oil or its derivates 

 is either cut or burned. If burning is planned, the contaminated 

 area is enclosed by fire lanes. Contaminated soils may be excavated, 

 removed, and replaced with other fill materials. Soil replacement 

 signals completion of the cleanup phase and the beginning of site 

 restoration. 



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