Spills and cleanup . 



1. Activity sequence 



Accidental discharge of crude oil, gas field brine, or other substances 

 occurs as a result of equipment failure, improper equipment operation, or 

 human error. Build-in safety mechanisms, if present, are activated auto- 

 matically to limit the quantity of discharge. Field personnel, once aware 

 of the spill or leak, immediately initiate procedures to confine dis- 

 charges to the smallest possible area. If the discharged materials enter 

 open-water bodies or intramarsh channels, then floating oil booms or sur- 

 face dams are used to contain the spill. Marsh buggies, air boats, and 

 motor boats may be employed for deployment trips and personnel transport. 

 Skimmer or vacuum units mounted on trucks or barges may be used to collect 

 floating oil and other buoyant petrochemicals. Straw or hay is scattered 

 to adsorb smaller, less accessible quantities that vacuum trucks cannot 

 remove. Specially manufactured absorbant sheets may be dispersed and then 

 later collected by hand. Standing vegetation coated with oil may be 

 flushed with water pumped through high-pressure hoses and hand cut and 

 removed from the site or burned in place to remove contaminants. Oil- 

 contaminated muds may be excavated with hand shovels or heavy machinery 

 depending upon site characteristics and spill size. Special dispersion 

 techniques may be necessary to discourage use of contaminated areas by 

 wildlife, primarily waterfowl and wading birds. Removal of contaminants 

 signals completion of the cleanup phase and the beginning of site resto- 

 ration procedures. 



2. Primary ecological alterations 



Alterations will vary according to the spill size, toxicity of the 

 chemical substances released, and cleanup methodology utilized. 



2.1 Introduction of toxic materials into water and soil system 



2.2 Complete above-ground removal of vegetation in spill zone 



2.3 Partial vegetation removal in adjacent areas during access and 

 cleanup phases 



2.4 Complete removal of selected consumer species in spill area 



2.5 Increased concentration of suspended sediments and dissolved nutri- 

 ents 



288 



