compacted nonporous soils, lack of vegetative cover, and increased pad 

 slopes and elevation, increases the transport of sediments and nutrients 

 into adjacent systems. 



Sediment and nutrient transport into adjacent wetlands or streams, how- 

 ever, may be of greater concern, as sediment introduction may cause 

 significant system changes. Analysis, therefore, requires treatment 

 through the appropriate aquatic ecosystem. Other soil structure aspects 

 include soil moisture and soil moisture and soil aeration linkages to the 

 flora; groundwater recharge, percolation, infiltration, and waterholding 

 capacity linkages to the hydrosphere; and evaporation pathways to the 

 atmosphere. Even though these aspects are seriously altered on the site 

 (usually reduced), they are not considered for further analysis because 

 either: (1) biotic effects are not relevant, since plant and animal 

 recovery is precluded by operational activities, or (2) the comparative 

 effects from a single small site on the ecosystem's hydrologic or atmos- 

 pheric regimes are minor. 



Small-scale releases of toxic substances inevitably occur at the complex 

 in spite of the preventive and maintenance procedures instituted. Eco- 

 logical alterations associated with larger spills and cleanup are treated 

 as a separate section of this discussion. Specific data documenting the 

 ecological effects of toxic chemical discharge into levee systems has not 

 been readily attainable in the scientific literature. However, soil 

 salinity, which restricts or prohibits vegetative growth, can be 

 increased by seepage of oil field brine. Ecological alterations as a 

 result of normal operational procedures are ^^ery restricted in area! 

 extent due to the low-volume discharge and limited lateral mobility of 

 substances through soil strata. Local biotic effects are a function of 

 the substance's toxicity, quantity released, mobility through the food 

 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 are treated 

 in a separate section of this discussion. The recuperative abilities of 

 the soil's micro-and macrobiota, as well as more complex flora, from 

 petrochemical discharges are not well understood. 



Disturbances associated with drilling and operational activities, vehi- 

 cular traffic, human presence, and noise initially cause short-term 

 wildlife displacement which may become long-term displacement. Nearby 

 nesting, foraging, and escape cover are degraded by the proximity of 

 continuous human activity and operational procedures. Sensitive wildlife 

 species avoid otherwise favorable habitats because of human intrusion 

 into formerly undisturbed environments; notable examples are the red wolf, 

 bald eagle, and whooping crane. The magnitude of such displacement is 

 difficult to assess, but it is still recognized as an important considera- 

 tion which extends project impacts beyond the boundaries of the immediate 

 site. 



310 



