Oilfield Remediation Options
Spill Investigation Program
A variety of remediation tactics are available for use depending the contaminant of concern.
Below is a list of tactics that have been used previously in North Dakota. This list is not
comprehensive, and other methods may be available.
The full technical requirements for each method are in the
Guidelines for the Assessment and Remediation of Oilfield Releases
.
Excavation
A common remediation tactic is to remove all impacted vegetation and soils.
Excavation can be used with most spilled materials.
Excavation — Steps and Requirements
When choosing excavation of a spill as the remediation tactic:
- Contact North Dakota One Call at 811.
- Fence around excavations for safety.
- Manage water in excavation.
- If an excavation is near a road, contact the officials responsible for the road safety.
- Dispose of contaminated materials at a permitted special waste landfill.
In most cases, excavation is required to continue until all remaining soils on site
are within NDDEQ action levels. However, if the excavation has reached a depth where
it is impractical to keep digging, the use of a capillary break or impermeable barrier
may be allowed with prior NDDEQ approval.
Read Section 4: Excavation in the guidelines
Water Removal
For spills impacting water, contaminated water removal is a quick response action
to reduce contamination and prevent it from spreading.
Water Removal — Methods and Disposal
When choosing water removal as a remediation tactic:
- Ensure any water removal equipment has been adequately cleaned.
- If water is intended to be used for flushing, ensure that the water is coming
from a dedicated freshwater tank.
- Carefully inspect any tanks or tubing for leaks.
- Dispose of removed water at a permitted disposal well.
Read Section 5: Water Removal in the guidelines
Soil Flushing and Amendments
Soil flushing uses water to flush contaminants from the site, typically using a drain
tile and sump system to collect water and contaminants for disposal.
Soil Flushing — Process and Requirements
Soil flushing:
- Requires significant amounts of water, often more than naturally occurring
precipitation.
- Requires varying amounts of time depending on the site soil properties.
- Often uses calcium amendments to help mobilize salt contaminants.
- Requires a detailed work plan be submitted to the NDDEQ in advance.
All amendments must be approved by the Division of Water Quality before use.
Read Section 7: Saltwater Remediation Techniques in the guidelines
Electrokinetics
Electrokinetics is a remediation method that uses direct current electrical fields
between two electrodes to separate contaminants from soil and groundwater.
Electrokinetics — Considerations and Requirements
Electrokinetics:
- Is typically used for saltwater contamination.
- Must first be assessed for feasibility.
- May remove beneficial salts from the soil.
- May have special water disposal requirements.
- Requires a detailed work plan be submitted to the NDDEQ in advance.
- Generates a waste stream of water that can carry a very high pH.
Read Section 7: Saltwater Remediation Techniques in the guidelines
Phytoremediation
Phytoremediation uses the planting, harvesting, and disposal of specific plant species
with the ability to uptake salts or other chemicals into their plant matter.
Phytoremediation — Process and Requirements
In situ bioremediation uses microorganisms to break down hydrocarbon contaminants
in soil or water.
Bioremediation — Considerations and Requirements
Burning
Burning is an option for some surface soil and water hydrocarbon impacts.
Burning — Permits and Requirements
Landfarming
Ex situ landfarming is a waste treatment process that uses microbes to degrade
hydrocarbon contaminants in soil.
Landfarming — Permit and Process
Natural Attenuation
Natural attenuation is the process of allowing the environment to break down
contamination without additional remediation action.
Natural Attenuation — Conditions and Requirements
Limited Action Option
In some circumstances, full remediation may not be possible in areas that are not
safely accessible or when remediation work would disrupt critical habitat, sensitive
vegetation, or cultural resources.
Limited Action Option — Conditions and Requirements
This method requires:
- A full horizontal and vertical delineation of the spill.
- A full site assessment and monitoring plan.
- Prior NDDEQ approval.
- A minimum of 3 years of monitoring or until the NDDEQ determines monitoring
is no longer needed.
Read Section 9: Limited Action Option in the guidelines
Experimental and Other Remediation Techniques
This is not a comprehensive list of available remediation tactics. The NDDEQ is always
interested in new and improved methods for spill remediation. Other remediation methods
may be allowed but may require a written work plan and prior NDDEQ approval.
Remediation Confirmation Sampling
For any remediation method chosen, the site must be confirmation sampled to prove
successful remediation. Additional details on sampling requirements can be found on the
Sampling Requirements & Action Levels page.
