Research at a 1979 crude oil spill from a ruptured pipeline has exposed and helped to overcome many challenges facing an effective, cost-efficient cleanup of crude oil, U.S. Geological Survey (USGS) scientists have found. The environmental release of crude oil occurred near Bemidji, Minnesota.
Although natural microbial activity has been degrading the plume of oil contaminants dissolved in groundwater, the crude oil trapped in the aquifer has provided a continuous source of dissolved hydrocarbon contamination to the groundwater contaminant plume.
In 1998, persisting contamination prompted the pipeline company to install a dual-pump recovery system targeted at removing crude oil in the subsurface that was floating on and above the water table. Wells extending to 3 meters below the water table were installed and pumped to create a cone of depression on the water table that would collect and enable withdrawal of residual crude oil. Crude oil was removed from each well using a pneumatic skimmer pump. The scientists had the opportunity to evaluate the performance of the remediation. They estimated that the remediation, which extended from 1999 to 2003, resulted in removal of about 115,000 liters of crude oil, 36 to 41 percent of the volume of oil (280,000 to 316,000 liters) estimated to be present in 1998.
Crude-oil recovery system implemented at the Bemidji, Minnesota, research site, 1999 to 2003. The crude-oil in the unsaturated zone above the water table contained a mixture of crude oil, air, and water in the sediment pore spaces (Delin and Herkelrath, 2014).
Remediation of crude oil from the aquifer is difficult, owing to sorption and entrapment of the oil in the pore spaces within sediments. Consequently, the oil-phase recovery was limited and considerable volumes of mobile and entrapped oil remain in the subsurface despite the remediation effort. The scientists also documented that management of wastes associated with the dual-pump recovery system is linked to expansion of the anoxic (oxygen deprived) zone of groundwater upgradient and beneath the existing contaminant plume.
The simple, cost-efficient monitoring methods used in this study, which included measuring oil thicknesses in wells and dissolved oxygen concentrations in groundwater, provided an inexpensive approach to evaluating the efficacy of the remediation.
In 2003, it was estimated that the United States has more than 240,000 kilometers (km) of oil pipeline. In 2011, the total amount of oil released annually was estimated at about 111,000 liters per 1,600 km of pipeline. Developing effective approaches for managing and remediating crude oil spills remains an essential precaution. This USGS Toxic Substances Hydrology Program research site is the only study site in the world tracking the long-term effects of a crude oil spill from a ruptured pipeline. Research at the site increases scientific understanding of the controls on the timeframe for the remediation and natural attenuation of petroleum hydrocarbons in the subsurface.
This research was supported by the USGS Toxic Substances Hydrology Program and the Hydrologic Research and Development Program.
Reference
Delin, G.N., and Herkelrath, W.N., 2014, Effects of dual-pump crude oil recovery system, Bemidji, Minnesota, USA: Ground Water Monitoring and Remediation, v. 34, no. 1, p. 57-67, doi:10.1111/gwmr.12040.
Related science listed below.
Cyclical Mobilization and Attenuation of Naturally Occurring Arsenic in an Underground Petroleum Plume
Understanding Pathways of Unconventional Oil and Gas Produced Water Spills in the Environment
U.S. Geological Survey Identifies Crude-Oil Metabolites in Subsurface Plumes
Remote Sensing Provides a National View of Cyanobacteria Blooms
Ethanol-Containing Fuel Spills Enhanced Natural Trace Element Release from Sediments in an Experimental Setting
Natural Breakdown of Petroleum Results in Arsenic Mobilization in Groundwater
- Overview
Research at a 1979 crude oil spill from a ruptured pipeline has exposed and helped to overcome many challenges facing an effective, cost-efficient cleanup of crude oil, U.S. Geological Survey (USGS) scientists have found. The environmental release of crude oil occurred near Bemidji, Minnesota.
Sources/Usage: Public Domain.USGS scientists collecting water-qualty samples from observation wells above a subsurface groundwater contamination plume. Photo credit: Jared Trost, USGS. Although natural microbial activity has been degrading the plume of oil contaminants dissolved in groundwater, the crude oil trapped in the aquifer has provided a continuous source of dissolved hydrocarbon contamination to the groundwater contaminant plume.
In 1998, persisting contamination prompted the pipeline company to install a dual-pump recovery system targeted at removing crude oil in the subsurface that was floating on and above the water table. Wells extending to 3 meters below the water table were installed and pumped to create a cone of depression on the water table that would collect and enable withdrawal of residual crude oil. Crude oil was removed from each well using a pneumatic skimmer pump. The scientists had the opportunity to evaluate the performance of the remediation. They estimated that the remediation, which extended from 1999 to 2003, resulted in removal of about 115,000 liters of crude oil, 36 to 41 percent of the volume of oil (280,000 to 316,000 liters) estimated to be present in 1998.
Crude-oil recovery system implemented at the Bemidji, Minnesota, research site, 1999 to 2003. The crude-oil in the unsaturated zone above the water table contained a mixture of crude oil, air, and water in the sediment pore spaces (Delin and Herkelrath, 2014).
Sources/Usage: Public Domain.Crude-oil recovery system implemented at the Bemidji, Minnesota, research site, 1999 to 2003. The crude-oil in the unsaturated zone above the water table contained a mixture of crude oil, air, and water in the sediment pore spaces. Remediation of crude oil from the aquifer is difficult, owing to sorption and entrapment of the oil in the pore spaces within sediments. Consequently, the oil-phase recovery was limited and considerable volumes of mobile and entrapped oil remain in the subsurface despite the remediation effort. The scientists also documented that management of wastes associated with the dual-pump recovery system is linked to expansion of the anoxic (oxygen deprived) zone of groundwater upgradient and beneath the existing contaminant plume.
The simple, cost-efficient monitoring methods used in this study, which included measuring oil thicknesses in wells and dissolved oxygen concentrations in groundwater, provided an inexpensive approach to evaluating the efficacy of the remediation.
In 2003, it was estimated that the United States has more than 240,000 kilometers (km) of oil pipeline. In 2011, the total amount of oil released annually was estimated at about 111,000 liters per 1,600 km of pipeline. Developing effective approaches for managing and remediating crude oil spills remains an essential precaution. This USGS Toxic Substances Hydrology Program research site is the only study site in the world tracking the long-term effects of a crude oil spill from a ruptured pipeline. Research at the site increases scientific understanding of the controls on the timeframe for the remediation and natural attenuation of petroleum hydrocarbons in the subsurface.
This research was supported by the USGS Toxic Substances Hydrology Program and the Hydrologic Research and Development Program.
Reference
Delin, G.N., and Herkelrath, W.N., 2014, Effects of dual-pump crude oil recovery system, Bemidji, Minnesota, USA: Ground Water Monitoring and Remediation, v. 34, no. 1, p. 57-67, doi:10.1111/gwmr.12040.
- Science
Related science listed below.
Cyclical Mobilization and Attenuation of Naturally Occurring Arsenic in an Underground Petroleum Plume
Scientists found that naturally occurring arsenic in aquifer sediments was mobilized into groundwater and attenuated through reattachment to sediments within an underground petroleum plume. Understanding these patterns identifies anthropogenic factors that affect arsenic presence and magnitude in groundwater.Understanding Pathways of Unconventional Oil and Gas Produced Water Spills in the Environment
A new study measures the transport of chemicals associated with unconventional oil and gas (UOG) produced waters downstream from a pipeline leak in North Dakota. This work is part of a long-term study designed to understand chemical persistence in sediments and water and how those factors might be related to contaminant exposures and associated with adverse health effects, if any, on organisms.U.S. Geological Survey Identifies Crude-Oil Metabolites in Subsurface Plumes
U.S. Geological Survey (USGS) scientists studying two subsurface crude-oil spill sites in Minnesota measured concentrations of oil breakdown products (metabolites) at greater concentrations than parent compound concentrations.Remote Sensing Provides a National View of Cyanobacteria Blooms
Four Federal agencies, including the U.S. Geological Survey (USGS), are collaborating to transform satellite data into information managers can use to protect ecological and human health from freshwater contaminated by harmful algal blooms.Ethanol-Containing Fuel Spills Enhanced Natural Trace Element Release from Sediments in an Experimental Setting
Experimental field research simulating hydrocarbon spills by researchers from the U.S. Geological Survey (USGS), Virginia Tech, and the University of St. Thomas showed that mixed ethanol and petroleum-based fuels increased the rate by which arsenic and other natural trace elements are released from aquifer sediments to groundwater when compared to petroleum-based fuels alone.Natural Breakdown of Petroleum Results in Arsenic Mobilization in Groundwater
Changes in geochemistry from the natural breakdown of petroleum hydrocarbons in groundwater promote mobilization of naturally occurring arsenic from aquifer sediments into groundwater. This geochemical change can result in potentially significant and overlooked arsenic groundwater contamination. Arsenic is a toxin and carcinogen linked to numerous forms of skin, bladder, and lung cancer. Of...