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Contaminant Issues - Oil Field Waste Pits

 

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Minimizing Risk to Migratory Birds in Oil and Gas Facilities

This 10:00 presentation is for oil and gas facility managers and staff to advise ways to reduce migratory bird and other wildlife mortality through best management practices.

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Oil and gas exploration and production is an important industry in the Region 6 states of Colorado, Kansas, Montana, Nebraska, North Dakota,Wyoming, and Utah. In many oil fields, water occurs in the oil reservoir and is extracted along with the petroleum particularly in older wells. Water or steam is also used in some wells to enhance the extraction of oil. During production, the process of separating oil and produced water using heat treaters is often ineffective. The produced water is either discharged into surface waters, injected underground, or transported to a commercial oil field waste disposal facility. Commercial oil field waste disposal facilities also pose significant risks to wildlife.


Commercial oil field waste disposal facilities »

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  • Commercial oil field. Credit: USFWS.

    Commercial oil field. Credit: USFWS.

  • Vacuum truck disposing water into COWDF. Credit: USFWS.

    Vacuum truck disposing water into COWDF. Credit: USFWS.

  • Oil and water separation occur in the main evaporation pond. Credit: USFWS.

    Oil and water separation occur in the main evaporation pond. Credit: USFWS.

  • Oil-covered bird. Credit: USFWS.

    Oil-covered bird. Credit: USFWS.

  • Grebe carcasses in a COFWDF evaporation pond. Credit: USFWS.

    Grebe carcasses in a COFWDF evaporation pond. Credit: USFWS.

  • Presence of visible sheens on the surface of evaporation ponds. Credit: USFWS.

    Presence of visible sheens on the surface of evaporation ponds. Credit: USFWS.

  • Surface contaminants. Credit: USFWS.

    Surface contaminants. Credit: USFWS.

Commercial and centralized oil field wastewater disposal facilities (COWDFs), like oil field waste pits, pose a significant risk to migratory birds and other wildlife because they use large evaporation ponds (either passive or with aeration) to dispose of and treat oil and gas exploration and production wastes. Commercial oilfield wastewater disposal facilities are operated for profit and receive wastewater from one or more oil and gas operators. A centralized oilfield wastewater disposal facilities is owned and operated by the same oil and gas company that operates the wells generating the wastewater disposed of into the facility. COWDFs that dispose of wastewater through deep well injection generally do not pose a risk to wildlife.

There are 72 COWDFs in Region 6 (30 in Colorado, 16 in Utah and 26 in Wyoming )(#'s as of October 2011). COWDFs are hazardous to wildlife as they accumulate significant quantities of oil on the surface of very large pits or evaporation ponds without effective wildlife exclusionary devices. Generally, COWDFs are operated in the following manner. Wastewater is initially disposed of into a receiving pit and the greatest amount of oil tends to float to the surface in that pit. Water from receiving pits is often sent to another pit or series of pits for evaporation or other management.

The following management practices make COWDFs a risk to the environment and migratory birds:

  • no site security such as fencing and locking gates to prevent unauthorized entry and the unauthorized disposal of wastes at the facility other than oil field produced water
  • accumulation of oil on the evaporation ponds
  • oil and water separation occur in the main evaporation pond
  • skim ponds or open topped separation tanks are not equipped to prevent entry by birds and other wildlife
  • presence of visible sheens on thesurface of evaporation ponds
  • concentrations of salts in the evaporation ponds may eventually cause hypersaline conditions which could pose a risk to migratory birds and cause mortality
  • surfactants or other chemicals present in the wastewater can cause birds to become waterlogged and cause mortality

Mirgatory bird mortality has been documents in oil field wastewater disposal facilities due to the presence of oil, paraffin, and sheens in the evaporation ponds. The presence of visible sheens on wastewater ponds are just as deadly to birds that come in 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.. Any oil or sheens remaining in the ponds in between the removal actions has the potential of coating birds or other wildlife coming into contact with it. Mortality or morbidity may result depending on the amount of oil coating the animal, the species, prior condition of the animal, the amound of stress incurred by the animal after oiling, and weather conditions.

Oily sludges remaining at the bottom of the impoundments as well as oil in the bank soil can seep onto the pond surface, especially during the summer when warm temperatures can mobilize the oil. Additionally, rainfall events or snowmelt will wash oil from the banks back into the pond. The chronic oiling can only be prevented by cleaning the banks, removing the oil-soaked soils and the bottom sludge.

High concentrations of salts can also pose a risk to migratory birds.  Birds entering ponds with hypersaline water can ingest the brine and die from sodium toxicity.  Salt toxicosis has been reported in ponds with sodium concentrations over 17,000 milligrams per liter (parts per million) (Windingstad, R.M. et al. 1987.  Salt toxicosis in waterfowl in North Dakota. Jour. Wildlife Diseases 23(3):443-446).  Ingestion of water containing high sodium levels can also pose chronic effects to aquatic birds, especially if a source of freshwater is not available nearby.  Aquatic birds ingesting hypersaline water can be more susceptible to avian botulism ( Cooch, F. G. 1964.  A preliminary study of the survival value of a functional salt gland in prairie Anatidae.  Auk 81:380-393).  During cooler temperatures, sodium in the hypersaline water can crystallize on the feathers of birds landing in these waterbodies.  The sodium crystals destroy the feathers' thermoregulatory and buoyancy functions causing the bird to die of hypothermia or drowning.  Sodium intoxication can cause neurological impairment resulting in the bird's inability to hold its head upright (Meteyer CU, Dubielzig RR, Dein FJ, Baeten LA, Moore MK, Jehl JR Jr and K Wesenberg. 1997. Sodium toxicity and pathology associated with exposure of waterfowl to hypersaline playa lakes of southeast New Mexico. J. Vet. Diagn. Invest. 9: 269-280).  The bird's head will droop into the water and cause it to drown.

If the evaporation pond is receiving produced water from oil or natural gas wells, oil and gas production chemicals, such as corrosion inhibitors and surfactants, could be present in the produced water and could pose a risk to migratory birds.  When a bird comes into contact with water containing surfactants, the surfactant will reduce the surface tension of the water; thus, allowing water to penetrate through the feathers and onto the skin.  This compromises the insulative properties of the feathers and subjects the bird to hypothermia (Stephenson, R. 1997. Effects of oil and other surface-active organic pollutants on aquatic birds.  Environmental Conservation 24(2):121-129).  The loss of water repellency by the feathers due to reductions in surface tension will cause the bird to become water logged and the loss of buoyancy will cause the bird to drown.

For more information, contact Pedro ‘Pete’ Ramirez, Jr. (Pedro_Ramirez@fws.gov)


Production skim pits »

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  • Earthen pit. Credit: USFWS.

    Earthen pit. Credit: USFWS.

  • Visible sheens on the production skim pit fluids. Credit: USFWS.

    Visible sheens on the production skim pit fluids. Credit: USFWS.

  • Oil in the berms of production skim pits can seep onto the pond surface. Credit: USFWS.

    Oil in the berms of production skim pits can seep onto the pond surface. Credit: USFWS.

Earthen pits are used to further separate oil from produced water using gravity-separation.  Oil or visible sheens on the surface of pit fluids pose a risk to migratory birds and other wildlife.  Birds, including hawks, owls, and songbirds, are attracted to oilfield production skim pits by mistaking them for natural bodies of water.  Oil pits also can attract bats, insects, small mammals, and big game.  Songbirds and mammals may approach oil-covered pits and ponds to drink, and can fall into the pits, or they can become entrapped if the banks of the pits are oiled. Insects entrapped in the oil can also attract songbirds, bats, and small mammals.  Hawks and owls in turn become victims when they are attracted by struggling birds or small mammals.  Service personnel have found waterfowl, songbirds, bats, pronghorn, and deer in oil pits and tanks.   The sticky nature of oil entraps birds in the pits and they die from exposure and exhaustion.  Birds that do manage to escape can die from starvation or the toxic effects of oil ingested during preening.  Birds ingesting sublethal doses of oil can experience impaired reproduction.

Visible sheens on the production skim pit fluids are just as deadly to birds.  It is critical to avoid the presence of any visible sheens on the surface of evaporation ponds, particularly during the breeding season as female aquatic birds returning to their nests with oil on their feathers can inadvertently apply the oil to the eggs.  Microliter amounts of oil applied externally to eggs are extremely toxic to bird embryos.   

Oil in the berms of production skim pits can seep onto the pond surface, especially during the summer when warm temperatures can mobilize the oil. Oily bottom sludges and oil-soaked soils along the banks of the ponds contribute sheens and oil onto the pit fluids, especially during hot summer days. Rainfall events or snowmelt will wash oil from the banks back into the pit.


Reserve pits »

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  • Reserve pit. Credit: USFWS.

    Reserve pit. Credit: USFWS.

  • Reserve pit. Credit: USFWS.

    Reserve pit. Credit: USFWS.

  • The presence of visible sheens on reserve pit. Credit: USFWS.

    The presence of visible sheens on reserve pit. Credit: USFWS.

  • The presence of visible sheens on reserve pit. Credit: USFWS.

    The presence of visible sheens on reserve pit. Credit: USFWS.

  • Earthen pit. Credit: USFWS.

    Earthen pit. Credit: USFWS.

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.

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.

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. 

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.

 


Flare pits »

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  • Flare stack. Credit: USFWS.

    Flare stack. Credit: USFWS.

  • Flare stack. Credit: USFWS.. Credit: USFWS.

    Flare pit. Credit: USFWS.. Credit: USFWS.

  • Flare stack. Credit: USFWS. Credit: USFWS.

    Flare stack. Credit: USFWS. Credit: USFWS.

Flare stacks are used at some oil production sites to vent and burn hydrogen sulfide gas produced from the wells.  Earthen pits are constructed below the flare stacks to contain any fluids present in the gas stream.  Typically, flare stacks collect precipitation which mixes with residual oils and other liquids and create small ponds which pose a hazard to migratory birds and other wildlife.

Exposed fluids in flare pits pose a hazard to migratory birds and other wildlife.  Effective exclusionary devices should be installed on flare pits to prevent wildlife entry.

Anti-perching devices should be installed on flare stacks to prevent raptors and other birds from using them as perch sites. Mortality of birds perching on flare stacks results from direct incineration or by inhalation of the toxic hydrogen sulfide gas if the flare igniter fails to work properly.  


Load line containers, drip buckets, dehydration tanks/tubs »

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  • Covered load line container. Credit: USFWS.

    Covered load line container. Credit: USFWS.

  • Uncovered load line container. Credit: USFWS.

    Uncovered load line container. Credit: USFWS.

  • Properly screened natural gas dehy tub. Credit: USFWS.

    Properly screened natural gas dehy tub. Credit: USFWS.

  • Improperly screened natural gas dehy tub. Credit: USFWS.

    Improperly screened natural gas dehy tub. Credit: USFWS.

  • Large mesh size allows entry by birds. Credit: USFWS.

    Large mesh size allows entry by birds. Credit: USFWS.

  • Birds and insects trapped in dehy tub. Credit: USFWS.

    Birds and insects trapped in dehy tub. Credit: USFWS.

Uncovered load line containers and drip buckets can entrap and kill birds. Load line containers should be covered to prevent entry by birds. 
Drip buckets should be covered with netting or wire mesh to prevent bird entry.

Natural gas dehydration unit tanks and “tubs” (dehy tubs) should be properly screened to exclude entry by birds. 


The problem »

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  • Production skim pit. Credit: USFWS.

    Production skim pit. Credit: USFWS.

  • Commercial or Centralized Oil Field Wastewater Disposal Facilities. Credit: USFWS.

    Commercial or Centralized Oil Field Wastewater Disposal Facilities. Credit: USFWS.

  • Reserve Pits. Credit: USFWS.

    Reserve Pit. Credit: USFWS.

  • Flare pit. Credit: USFWS.

    Flare pit. Credit: USFWS.

  • Oil covered bird. Credit: USFWS.

    Oil covered bird. Credit: USFWS.

  • Sheen on water surface and various wildlife fatalities from oil contamination. Credit: USFWS.

    Sheen on water surface and various wildlife fatalities from oil contamination. Credit: USFWS.

In many oil and natural gas fields, water occurs in the oil or gas reservoir and is extracted along with the petroleum particularly in older wells. Water or steam is also used in some wells to enhance the extraction of oil. During production, the process of separating oil and produced water using heat treaters is often ineffective. Production skim pits or open-topped tanks are used to further separate oil from produced water. The produced water is either discharged into surface waters, injected underground, or transported to a commercial oil field waste disposal facility. Commercial oil field waste disposal facilities also pose significant risks to wildlife. Reserve pits used during drilling operations to store drilling fluids can also cause bird and wildlife mortality if they contain visible sheens or oil on the surface. Flare pits, earthen pits constructed below flare stacks used to vent hydrogen sulfide gas from production wells can also cause bird and wildlife mortality if they contain visible sheens or oil on the surface. Exposed oil in load line containers, drip buckets, dehydration tanks or tubs, and well chemical spill containment devices at oil and gas production facilities can also attract and entrap migratory birds. Some oil operators still continue to use colored flagging at oil skim pits and reserve pits to deter birds. Flagging is not effective at preventing wildlife mortality in oil pits.

  • Skim ponds are a fatal attraction to migratory birds Birds, bats, and other wildlife mistake these oily pits for wetlands
  • Birds landing on waste pits can get covered with oil
  • Oil can weigh birds down and cause them to drown
  • Many bird deaths go undetected because the carcasses sink to the bottom of the pits
  • Oil destroys the feathers' ability to insulate the birds resulting in death from heat or cold stress
  • Even a light sheen on the water surface can be deadly. Oil on the feathers of female bird can be transferred to their eggs back at the nest, killing the embryo.
  • Small amounts of oil applied externally to the egg shells are extremely toxic to embryos
  • Some birds become victims of pits when they feed on insects trapped in oil covering the surface of the water.
  • Waterfowl are not the only victims. Songbirds are attracted to pits by insects entrapped in the oil. Hawks and owls in turn become victims when they are attracted by struggling birds or small mammals.
  • Exposed oil waste pits, hazardous materials spills, and oil spills can result in migratory bird mortalities.
  • The Migratory Bird Treaty Act (16 USC 703-711) prohibits the "taking" of migratory birds
  • Eagle mortalities cause by oil pits is a violation of the Bald Eagle Protection Act
  • Mortality of threatened and endangered birds or other wildlife in oil pits is a violation of the Endangered Species Act
  • It doesn't take much oil to entrap songbirds such as this horned lark. Cleanup of all spilled oil is essential to prevent wildlife mortality.

It doesn't take much oil to entrap songbirds such as this horned lark. Cleanup of all spilled oil is essential to prevent wildlife mortality.

 


Solutions »

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  • Closed containment system. Credit: USFWS.

    Closed containment system. Credit: USFWS.

  • Oil spil clean up. Credit: USFWS.

    Oil spil clean up. Credit: USFWS.

  • Netting covering waste pit. Credit: USFWS.

    Netting covering waste pit. Credit: USFWS.

  • Flagging over waste pit is an ineffective deterrent. Credit: USFWS.

    Flagging over waste pit is an ineffective deterrent. Credit: USFWS.

Solutions to preventing wildlife mortality in oil field waste pits are fairly simple and straight forward and are being implementing by many oil operators. The U.S. Fish and Wildlife Service suggests the following measures.

Use Closed Containment Systems

Closed containment systems require little or no maintenance and the system can be moved to a new site when the well is shut in. Closed containment systems eliminate soil contamination and remediation expense. Closed containment systems used to collect oil field produced water do not attract wildlife and isolate oil from the environment.

Eliminate Pits or Keep Oil Off Open Pits or Ponds

A fail-safe solution is to remove the pits or keep oil from entering the pits. Immediate clean up of oil spills into open pits is critical to prevent wildlife mortalities.

Use Effective and Proven Wildlife Deterrents or Exclusionary Devices

Netting appears to be the most effective method of keeping birds from entering waste pits.


Deterrents That DO NOT Work at Oil Pits

Flagging is ineffective at deterring migratory birds and other wildlife from oil field waste pits.

  • Reflectors
  • Strobe Lights
  • Zon Guns

Published scientific studies as well as field inspections by U.S. Fish and Wildlife Service personnel have documented bird mortalities at oil pits with flagging, reflectors, and strobe lights. Although Zon guns or propane cannons have been used in other applications to deter birds, their use in oil pits have been ineffective.

 


  • Properly installed net. Credit: USFWS.

    Properly installed net. Credit: USFWS.

  • This net was installed less than 5 feet above the fluid surface. A heavy snow-load caused the net to sag into the oil-covered pond. The exposed oil entrapped migratory birds. Credit: USFWS.

    This net was installed less than 5 feet above the fluid surface. A heavy snow-load caused the net to sag into the oil-covered pond. The exposed oil entrapped migratory birds. Credit: USFWS.

  • Poorly installed and maintained netting at this commercial oil field produced water disposal facility in Wyoming allows entry by migratory birds and other wildlife. Credit: USFWS.

    Poorly installed and maintained netting at this commercial oil field produced water disposal facility in Wyoming allows entry by migratory birds and other wildlife. Credit: USFWS.

  • The large mesh shown in this photo will allow entry by songbirds and small mammals into the production skim pot. Credit: USFWS.

    The large mesh shown in this photo will allow entry by songbirds and small mammals into the production skim pot. Credit: USFWS.

  • Cottontail rabbits are shown in the photo both outside and insidethe netted pit area. The cottontail in the upper center of the photo has entered through this small opening on the side of the net. Credit: USFWS.

    Cottontail rabbits are shown in the photo both outside and insidethe netted pit area. The cottontail in the upper center of the photo has entered through this small opening on the side of the net. Credit: USFWS.

Effective Net Installation

The effectiveness of netting oil pits to exclude birds and other wildlife depends on its installation. Effective installation requires a design allowing for snow-loading and one that also prevents ground entry by small mammals and birds. According to a professional net installation contractor, a maximum mesh size of 1 1/2 inches will allow for snow-loading and will exclude most birds. Netting should be suspended a minimum of 4 to 5 feet from the surface of the pond to prevent the net from sagging into the oil-covered pond during heavy snow-loads. Three-inch steel tubing can be used for support posts and are set a maximum of 7 feet apart. These are buried a minimum of 7 feet in depth and set in concrete. Three-inch steel tubing is also used as a top rail to connect the posts. Cable is strung across this frame at 7-foot intervals along the y-axis and the x-axis to form a grid of 7-foot squares by the cable. The netting is draped over this cable grid. Netting should be wide enough to drape down the sides of the frame to prevent ground entry by wildlife. A bottom perimeter cable strung along the bottom of the posts at ground level is used to attach the bottom of the net. Cables are strung over the net at 7-foot intervals to prevent the wind from whipping the net back and forth. Proper maintenance should be performed to repair holes in the netting and to re-stretch sagging nets after heavy snow-loads.

Properly installed net at commercial oil field produced water disposal facility in Wyoming. Net is supported by steel frame and high-tensile strength cable to prevent sagging. Sides are also netted to prevent ground entry by birds and other wildlife. Netting to exclude migratory birds should also extend down the sides of the supporting frame to prevent ground entry by birds and other wildlife.

Netting should be suspended a minimum of 4 to 5 feet from the surface of the pond to prevent the net from sagging into the oil-covered pond during heavy snow-loads.

To insure effectiveness, netting should exclude wildlife from ground as well as aerial entry.

Proper maintenance is necessary to prevent wildlife and migratory birds from entering oil-covered pits.

Mesh size is critical to prevent the entry of songbirds and small mammals.

In Summary . . .

  • Netting has been found effective at deterring birds from oil pits.
  • HDPE balls have been used as bird deterrents in waste pits.
  • Use enclosed tanks to separate the oil from the produced water prior to discharge into the environment.
  • Industry compliance with existing state and federal regulations prohibiting the accumulation of oil in separator pits.
  • Report migratory bird deaths in oil pits to the nearest U.S. Fish & Wildlife Service office.

For more information, contact Pedro ‘Pete’ Ramirez, Jr. (Pedro_Ramirez@fws.gov)


Links to more information »

The mission of the U.S. Fish and Wildlife Service is working with Others to conserve, protect, and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American People.
Last modified: February 09, 2018
All Images Credit to and Courtesy of the U.S. Fish and Wildlife Service Unless Specified Otherwise.
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