National Petroleum Reserve in Alaska: Legacy Wells Summary Report
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2018-05-03
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Meares, Terra. Master of Environmental Assessment.
National Petroleum Reserve in Alaska: Legacy Wells Summary Report.
Between 1944 and 1982, the United States Navy (Navy) and the United States Geological Survey (USGS) drilled a total of 136 on-shore core and test wells within what is referred to today as the National Petroleum Reserve in Alaska (NPR-A), an area set aside for oil and gas exploration shortly after World War I. The 136 wells vary in site features and complexity, depending upon when the well was drilled, and can include cellars, drilling pads, and reserve pits. Upon completion of these programs, materials and debris indicative of past activities were left behind, along with scars in the delicate tundra. The NPR-A is an area consisting of nearly 23 million acres of Alaska’s wilderness, a crucial habitat for caribou, polar bears, grizzly bears, and many species of raptors and other waterfowl that rely on the lands for summer migration and nesting. Additionally, local native communities rely heavily on subsistence hunting, fishing and whaling throughout the NPR-A. Each of the 136 wells, now termed legacy wells, require a thorough risk characterization due to their potential for adverse effects to human and environmental health from past oil drilling and exploration activity.
The focus of this report includes adding more precise well coordinates, defining well site boundaries, thoroughly evaluating analytical data and historical records, as well as reviewing updated site inspections and remediation efforts. This report will supply the information necessary to produce a strategic plan, obtain funds and, potentially technical assistance, in the ongoing cleanup of these wells. An overall environmental risk assessment was conducted that considered the collected data from each site. There were two main environmental risk assessments performed: surface risks and subsurface risks. Conditions that resulted in a high surface risk included known contaminants above Method Two Arctic Zone state cleanup levels, the potential threat from accelerated coastal erosion, significant solid waste present affecting visual resources or public safety, and/or the potential to affect air or water quality due to the discharge of hydrocarbons under pressure. A well or core test was assigned a high subsurface risk if there was evidence of leaking hydrocarbons, and/or if the well or core test penetrated oil or gas stratigraphy.
Of the 136 wells 81 require no additional action, 18 wells are in use by the USGS for temperature monitoring, and 3 wells are being monitored by the BLM. The remaining 34 wells currently require attention in the form of surface remediation and/or plugging of the well. Some sites exhibited extensive surface debris, were threatened from coastal erosion (with potential of releasing contaminants into the surrounding environment), or had remains of an extensive underground refrigerant system of pipes (containing unknown amounts of diesel fuel).
There is still not enough substantial information available on potential contaminants related to previous drilling operations and actions at the majority of the legacy wells in order to produce a comprehensive assessment, however this summary report has identified a clear data gap. Future opportunities include producing site maps of known surface debris, burial sites, and locations of past and/or present spills, as well as breach locations from the reserve pits. Sampling plans can then be produced and executed for each of the well sites exhibiting a low surface risk or greater. The results can then be added to this current summary report in order to both reassess the site risks, update the status of the sites, and to continue the overall efforts in managing the legacy wells.
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National Petroleum Reserve Alaska; legacy wells; risk assessment; drilling; plugging and abandonment; Bureau of Land Management
