Oilfield pits are ground excavations (earthen storage) designed for storing liquids and sludges utilized in or produced during oil and gas exploration and production operations. The first oilfield pit in Louisiana was excavated in the first oilfield in Louisiana in conjunction with the first oil well in the Evangeline Field in the early 1900’s. The Evangeline Field was plagued by pollution due to discharge of oilfield produced saltwater. A harbinger of things to come for Louisiana.
Why Were Oilfield Pits Used?
Due to a lack of transportation and storage options (trucking, pipelines, shipping, and rail) in the early oilfields, oil companies would dig a pit surrounded by an earthen berm to store drilling mud for drilling the well. These companies would then use that pit or dig another pit to store the produced oil until it could be brought to market. These companies would also have a pit to store and dispose of produced salt water if that waste was not discharged into a nearby surface water body.
Despite the rapid industrialization of the oilfield and development of pipelines, trucking systems, and the expansion of rail transport early on, oil companies continued utilizing unlined earthen pits in their Louisiana operations until the mid to late 1980’s.
Types of Oilfield Pits
Oil companies in Louisiana utilized earthen storage pits for a variety of purposes over time. Due to the nature of the operations, some of these pits are much more likely to retain contamination.
- Drilling Pit – pit used to store drilling mud which is needed to lubricate the drilling bit and clean out the wellbore while drilling a well.
- Production Pit – a pit used to store oil produced from a reservoir while waiting to transport to market
- Disposal Pit – a pit used to dispose of oilfield wastes, including produced waters during exploration and production operations. Historically, oil companies falsely claimed that these wastes would evaporate.
- Burn Pit – a pit used to burn wastes from exploration and production operations including waste oil and solid wastes such as contaminated road boards and chemical packaging,
- Flare Pit –a pit containing flaring equipment where liquid hydrocarbons are sent which are not burned in the primary flare due to equipment malfunction. Flare pits are also used for diversion and flaring of gas from over-pressured reservoirs during drilling.
- Retention Pond – a pit used to store water for fire prevention and control purposes. Retention ponds also collect rainwater to keep other pits from overflowing.
- Frac Pit – Reserve pit used during hydraulic fracturing operations. These pits are used to hold flow back and produced water during drilling, treating water and sludge after drilling, or holding fresh water for mixing with fracking sands.
Groundwater & Soil Contamination from Unlined Pits
Notwithstanding their continued use through the 1980’s, the oil industry has collectively known since the 1930’s that the disposal of oilfield wastes in unlined earthen pits would inevitably result in seepage of the waste contents contaminating both surface and subsurface soils and water. Pit contents often include technologically enhanced naturally occurring radioactive material (TENORM), produced waters, drilling fluids, chlorides, hydrocarbons and heavy metals.
NORM or TENORM contains Radium226 and Radium228, which are known human carcinogens. These very hazardous and toxic substances are only “naturally occurring” at the depths from which oil and gas are produced and thus their presence on the surface can cause serious health problems.
Produced water is a mixture of water with various hydrocarbon components, metals, salts, and radioactive substances. Produced water is brought to the surface from the reservoir when oil is produced. In a similar vein, drilling fluids contain metals such as chromium, barium and arsenic, as well as hydrocarbon fractions. Drilling fluids also contain toxic additives such as bactericides, slimicides, and acids.
In addition to seepage, pits also cause contamination of soils and groundwater through overflow due to heavy rains or inadequate sizing. Another avenue for migration of contamination from oilfield pits is intentional and accidental discharge. It is astounding how frequently oilfield workers intentionally drain a pit onto a landowner’s property for maintenance, to reduce pit levels, and other reasons. Finally, leaks, spills, and other discharges when moving liquids and sludges to and from pits during drilling and production operations is source of property contamination.
Other Risks to Human Health and the Environment
The primary concern of contaminated oilfield pits is migration of that contamination from the pit to the groundwater and particularly drinking water aquifers. However, un-remediated or improperly closed pits can cause significant damage to nearby vegetation as well as kill wildlife that are attracted to pits as a source of water. Contaminated pits also cause significant risk for agricultural operations including unsafe crops and cattle deaths.
Regulation – Emergency Rule (29-b)
Notwithstanding the fact that the oil industry was aware of the significant pollution risks associated with unlined earthen pits since at least the 1930’s, oil companies continued to use unlined pits through the 1980’s because they were not banned by regulation or legislation.
Despite the fact that much of the wastes produced during oil and gas exploration and production are toxic, most are not subject to federal hazardous waste law – the Resource Conservation and Recovery Act (RCRA). This is because the oil industry lobbied Congress for an exemption that was granted despite the fact that toxic substances are contained in the wastes.
In 1986, in the absence of comprehensive federal oilfield regulation, the Louisiana Department of Natural Resources (Office of Conservation) amended Statewide Order 29-B, L.A.C. 43:XIX.101, et seq. in order to require the registration and closure of existing unlined oilfield pits. In expectation of the promulgation of pit, many oil companies rushed to fill or abandon their pits before the regulations took place.
These improperly closed and un-remediated pits are legacy of Louisiana’s oil industry. Unbeknownst to landowners, numerous properties throughout Louisiana are contaminated by pits leftover from pre-1986 oil and gas operations. These pits frequently inundated and often mistaken for ponds. In a wetland setting, improperly closed pits can also lead to significant erosion.
If you are the owner of property on which oil and gas operations were conducted and are concerned about improperly closed pits, please call Stag Liuzza, LLC at 504-593-9600 for a free consultation.
 These regulations cover pollution control, waste storage, and pit closure requirements amongst other things.