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Region 6 Environmental Contaminants

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Contaminant Issues - Oil Field Waste Pits
  
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Reserve Pits

Oil present in reserve pit fluids can entrap and kill migratory birds and other wildlife. Fluids containing oil or oil-based products should be removed as soon as possible from the reserve pits after well completion to prevent migratory bird mortality or the reserve pit should be properly closed.  Bird and other wildlife mortality in reserve pits has been documented by the Service.

remove fluid

Drilling fluids containing oil or oil-based products should be removed as soon as possible from reserve pits after well completion to prevent migratory bird mortality or the reserve pit should be closed as soon as possible.  If fluids containing oil or sheens cannot be removed from the reserve pit, then the pit should be covered with netting to prevent bird and other wildlife access. 

Flagging is ineffective at deterring birds from reserve pits. 

flagging

The presence of visible sheens on reserve pits are just as deadly to birds that come into contact with them. A light sheen will coat the bird’s feathers with a thin film of oil. Although a sheen of oil on the bird may not immediately immobilize the bird, it will compromise the feathers’ ability to insulate the bird. Furthermore, the affected bird will ingest the oil when it preens its feathers and suffer chronic effects. The bird could suffer mortality depending on the severity of the chronic effects and the amount of oil ingested. 

sheen

Typical reserve pit closure involves leaving the pit in place after well completion to allow the fluids to dry. If the reserve pit contains oil or oil-based products (i.e. oil-based drilling fluids), the pit can entrap and kill migratory birds and other wildlife. Pitless (closed-loop) drilling has been found to reduce the amount of drilling waste, recycles drilling fluids, and reduces drilling costs. Pitless drilling can also reduce the volume of waste by 60 to 70 percent, conserves water and prevents soil contamination.

The use of earthen pits to contain drilling muds and fluids can contaminate soil, groundwater, and surface water with metals and hydrocarbons if not managed and closed properly. The complete elimination of earthen pits for drilling waste disposal is the key to the effectiveness of pitless drilling. Earthen pits used for disposal of drill cuttings will collect rainwater and or snowmelt and thus pose a risk to migratory birds and other wildlife as do conventional reserve pits.



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