City of Poplar Well Threat Plume Capture and Remediation Team
U.S. Geological Survey, Fort Peck Indian Reservation, Montana
Project Point of Contact
Joanna Thamke, USGS
The City of Poplar—headquarters for the Assiniboine and Sioux tribes of the Fort Peck Indian Reservation—provides water to nearly 3,000 residents most of whom are tribal members. The only source of potable ground water for these residents is a shallow sand and gravel aquifer. As early as the 1970's, billions of barrels of brine began infiltrating the aquifer, privately owned wells, and the nearby Poplar River. The brine is produced as a by-product of the nearby by oil fields in operation since 1952 and is seven times saltier than ocean water. In one area, a lens of crude oil was also encroaching on the aquifer.
After a series of U.S. Geological Survey studies from 1980s – 2000, and short term solutions mandated by EPA, the project took an innovative leap forward in 2003 when a team of scientists from the U.S. Geological Survey, Fort Peck Tribes Office of Environmental Protection, Pioneer Natural Resources USA, Inc. (the potentially responsible party), U.S. Bureau of Land Management, U.S. Environmental Protection Agency, and U.S. Bureau of Reclamation worked together on an expanded remediation study. They successfully combined geophysical, hydrological, and geological methods to create a "snapshot" of the plume configuration prior to remediation. Subsequent geophysical data "snapshots" along with water chemistry data from monitoring wells during brine remediation document the remediation's progress. The unique combination of methods and collaboration used to document remediation progress is unprecedented, and these techniques will likely supplement future industry standards for monitoring remediation.
Open communication and data sharing are the hallmarks of this team project. Numerous meetings with scientific agencies, regulatory agencies, and the oil company conducted in a spirit of cooperation enabled all to meet the common goal of capturing and remediating the imminent threat to the City of Poplar. Strong support from the team of scientists resulted in project funding of more than $1.5 million since 2003 to delineate the brine contamination. In addition to the EPA-ordered work, the potentially responsible party has proactively and voluntarily committed more than $6 million during the past 6 years to design and build a plume capture and remediation system. The remediation system and a project to plug a contamination source has and will continue to improve water quality in the aquifer. This project improves a valuable natural and cultural resource in relation to the traditional ways of the Assiniboine and Sioux Tribes' way of life and the City of Poplar's water supply.
- U.S. Geological Survey (USGS)
- Fort Peck Tribes Office of Environmental Protection (FPOEP)
- Pioneer Natural Resources USA, Inc. (PNR)
- U.S. Bureau of Land Management (BLM)
- U.S. Environmental Protection Agency (EPA)
- U.S. Bureau of Reclamation (BOR)
Need and Implementation:
The City of Poplar—headquarters for the Assiniboine and Sioux tribes of the Fort Peck Indian Reservation—provides water to nearly 3,000 residents most of whom are tribal members. The only source of potable ground water for these residents is in a shallow sand and gravel aquifer. Beneath the sand and gravel unit, rock units are dry or contain water that is too salty for household use. The community can not afford the expensive infrastructure and treatment facilities required to use surface water from the nearby Missouri River. Therefore, the water in the shallow sand and gravel is invaluable.
The shallow sand and gravel has become contaminated with brine that is produced with oil in the nearby East Poplar oil field (see Attachment 1. Overview of East Poplar oil field). Billions of barrels of brine, which can be 7 times saltier than ocean water, have been produced from this field since 1952. Disposal and handling methods of the brine have resulted in contamination of more than 12 square miles of shallow ground water as well as the nearby Poplar River (Thamke and Craigg, 1997 and pg 7 of Attachment 1). These impacted lands are managed by the Fort Peck Tribes and Bureau of Indian Affairs. Privately-owned wells have become contaminated. Affected residents have resorted to hauling water from town, purchasing bottled water with limited incomes, moving, and/or tolerating the declining quality of their water. The city wells are less than 2 miles downgradient of brine-contaminated domestic wells.
In 1999, 2001, and 2004, EPA issued Emergency Orders to a consortium of oil companies to address the ground-water contamination. In response, the companies supplied bottled water to about 20 residents with contaminated water wells, built a water pipeline from the City of Poplar to these 20 residents, and provided hydrologic and oil-activity data pertinent to their facilities.
A regional investigation by the USGS identified several areas of subsurface brine contamination in the East Poplar oil field (Thamke and Craigg, 1997). The nearest source of brine contamination to the City of Poplar is an abandoned oil well that is estimated to have been leaking for nearly 20 years. Water in this plume is hot (202 oF) with extremely high chloride concentrations (44,700 mg/L). Prior to contamination, ground water at this site was cool (45 oF) and had low chloride concentrations (less than 100 mg/L). After PNR acquired ownership of this leaking well during a merger with another company in 1997, the well was successfully plugged.
In addition to the EPA-ordered work, PNR has proactively and voluntarily committed more than $6 million during the past 6 years to design and build a plume capture and remediation system. Open and constructive discussions between scientists from USGS, FPOEP, PNR, EPA, and BLM have guided capture and remediation plans for the plume. Scientists on this team have been recognized with the 2007 and 2008 Research Awards by the American Association of Petroleum Geologists Division of Environmental Geosciences. Strong support from USGS, FPOEP, BLM, EPA, and BOR has resulted in project funding of more than $1.5 million since 2003 to delineate the brine contamination. A cooperative team spirit has expedited the completion of this system to remove an imminent threat to the City of Poplar's public-water supply.
Brine-contamination problems are not uncommon in aging oil fields throughout the United States. Contamination was first noted in the East Poplar oil field in the late 1970's, nearly thirty years after the start of the oil field. The USGS identified a small area of contamination near the Poplar River (Levings, 1984). In the late 1980's other well owners reported increased salinity of their well water. In the 1990s, the USGS used an innovative combination of hydrology, geology, and geophysics to delineate as much as 12 mi2 of contamination in the shallow sands and gravels (Thamke and Craigg, 1997). However, the contaminated area was larger than the area studied in the 1990's, and an expanded study that used an innovative combination of airborne geophysics with hydrology and geology was started in 2003 (Smith and others, 2006 and pgs 12-14 of Attachment 1).
The successful implementation of the combining geophysical, hydrological, and geological methods will be used to monitor the efficiency of the brine remediation system. Geophysical data collected in May 2008 has been compared to ground-water chemistry and the airborne geophysical maps to create a "snapshot" of the plume configuration prior to remediation (pg. 21 of Attachment 1). Subsequent geophysical data "snapshots" along with water chemistry data from monitoring wells during brine remediation will be useful to document the progress of the remediation. Use of these methods to document remediation progress is unprecedented, and these techniques will likely be used to supplement future industry standards for monitoring remediation.
Partnering and Cooperative Conservation:
Open communication and data sharing are the hallmarks of this team project. Numerous meetings with scientific agencies, regulatory agencies, and the oil company were conducted in a spirit of cooperation with the common goal to capture and remediate the imminent threat to the City of Poplar. Data and interpretations gathered by the various entities have been shared and discussed to ensure an accurate and thorough understanding of the brine contamination in the area. A technical advisory team of USGS and FPOEP scientists reviewed a detailed ground-water model of the remediation system to ensure best placement of pumping and monitoring wells (DBS&A, 2007).
In addition to data and information sharing, expensive geophysical equipment owned by the USGS has been made available for FPOEP and PNR to collect critical geophysical data. These data show a "snapshot" of the brine plume prior to remediation and will continue to be collected to document the remediation.
Scope of Project Impact:
Scientists from the team identified that a major on-going leaking source of brine contamination was an abandoned oil well. Shortly after the well was successfully plugged, chloride concentrations and temperature in water from nearby monitoring wells began to improve. As fresh water recharges the aquifer in this area, the chemistry of the aquifer continues to improve (see pg 17 of Attachment 1).
In addition to the brine impacted ground water, a lens of crude oil has contaminated an estimated 7 acres in the immediate vicinity of the plugged oil well. It is estimated that there is approximately 3,350 bbls of crude oil in this lens. In June 2007, a remediation system designed to remove the crude oil lens was implemented. The remediation system has removed approximately 85 bbls of crude oil to date and is capable of removing 2.5 bbls of crude oil per day. Additional remediation is underway to enhance the recovery of the crude oil with the use of a dual-pump configuration in which a water pump will be placed at the base of the well and pumped to lower the water/oil interface across the product (crude oil) recovery pumps above. This should greatly enhance the recovery rates.
The brine remediation system will be fully operational in August 2008. The designed system will remove the most contaminated portion of the plume that covers 426 acres to significantly reduce the threat to the City of Poplar. This project has and will continue to improve a valuable natural and cultural resource in relation to the traditional ways of the Assiniboine and Sioux Tribes' way of life.
- Daniel B. Stephens and Associates, Inc., 2007, Groundwater monitoring for Biere well brine plume remediation system design: prepared for Pioneer Natural Resources, Inc. USA, 17 p.
- Levings, G.W., 1984, Reconnaissance evaluation of contamination in the alluvial aquifer in the East Poplar oil field, Roosevelt County, Montana: U.S. Geological Survey Water-Resources Investigations Report 84-4174, 29 p.
- Smith, B.D., Thamke, J.N., Cain, M.J., Tyrrell, C., and Hill, P.L., 2006, Helicopter electromagnetic and magnetic survey maps and data, East Poplar Oil Field Area, Fort Peck Indian Reservation, Northeastern Montana, August 2004: U.S. Geological Survey Open-File Report, 2006-1216, 18 p.
- Thamke, J.N., and Craigg, S.D., 1997, Saline-water contamination in Quaternary deposits and the Poplar River, East Poplar oil field, northeastern Montana: U.S. Geological Survey Water-Resources Investigations Report 97-4000, 37 p.DBS&A, 2007