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Contaminant Issues - Oil Field Waste Pits

The Problem - Solutions - Links - Return to Oil Field Waste Pits

Solutions

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

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.

photo of a bird carcass in a flag-covered pit


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.

effective nets    

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


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. 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.
poor netting

Poorly installed and maintained netting at this commercial oil field produced water disposal facility in Wyoming allows entry by migratory birds and other wildlife. To insure effectiveness, netting should exclude wildlife from ground as well as aerial entry.
ineffective netting

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

rabbit net

 

Mesh size is critical to prevent the entry of songbirds and small mammals. The large mesh shown in this photo will allow entry by songbirds and small mammals into the production skim pot.

mesh size

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)

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