Drill Cuttings - Waste

Waste

Burial Pits and Land Farming

Burial is the placement of waste in man-made or natural excavations, such as pits or landfills. Burial is the most common onshore disposal technique used for disposing of drilling wastes (mud and cuttings). Generally, the solids are buried in the same pit (the reserve pit) used for collection and temporary storage of the waste mud and cuttings after the liquid is allowed to evaporate. Pit burial is a low-cost, low-tech method that does not require wastes to be transported away from the well site, and, therefore, is very attractive to many operators.

Burial may be the most misunderstood or misapplied disposal technique. Simply pushing the walls of the reserve pit over the drilled cuttings is generally not acceptable. The depth or placement of the burial cell is important. A moisture content limit should be established on the buried cuttings, and the chemical composition should be determined. Onsite pit burial may not be a good choice for wastes that contain high concentrations of oil, salt, biologically available metals, industrial chemicals, and other materials with harmful components that could migrate from the pit and contaminate usable water resources.

In some oil field areas, large landfills are operated to dispose of oil field wastes from multiple wells. Burial usually results in anaerobic conditions, which limits any further degradation when compared with wastes that are land-farmed or land-spread, where aerobic conditions predominate.

The objective of applying drilling wastes to the land is to allow the soil's naturally occurring microbial population to metabolize, transform, and assimilate waste constituents in place. Land application is a form of bioremediation, and is important enough to be described in its own fact sheet; other forms of bioremediation are described in a separate fact sheet.

Several terms are used to describe this waste management approach, which can be considered both treatment and disposal. In general, land farming refers to the repeated application of wastes to the soil surface, whereas land spreading and land treatment are often used interchangeably to describe the one-time application of wastes to the soil surface. Some practitioners do not follow the same terminology convention, and may interchange all three terms. Readers should focus on the technologies rather than on the specific names given to each process.

Optimal land application techniques balance the additions of waste against a soil's capacity to assimilate the waste constituents without destroying soil integrity, creating subsurface soil contamination problems, or causing other adverse environmental impacts.

Drill Cuttings can contain N.O.R.M. (Naturally Occurring Radioactive Material). The levels of radiation that are emitted by these cuttings can be high enough to trigger the radiation detectors at the landfill.