Overview:
When hazardous liquids are released from pipelines or other containment structures into surrounding soils, pipeline operators must take actions to limit impacts and perform cleanup, in accordance with requirements of the Environmental Protection Agency as well as local jurisdictional agencies.
People who respond to spills of hazardous liquids undergo scenario training that equips them to employ various methods of containment and removal, depending on existing environmental conditions, as well as the severity and type of spill encountered.
Applicable Regulations
The following regulations and laws apply to spill response.
- 40 CFR Part 300, National Oil and Hazardous Substances Pollution Contingency Plan . The purpose of the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) is to provide organizational structure and procedures for preparing for and responding to discharges of oil, and releases of hazardous substances, pollutants, and contaminants.
- 40 CFR Part 302, Designation, Reportable Quantities, and Notification . This regulation designates, under section 102(a) of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (‘‘the Act’’) those substances in the statutes referred to in section 101(14) of the Act, identifies reportable quantities for these substances, and sets forth the notification requirements for releases of these substances. This regulation also sets forth reportable quantities for hazardous substances designated under section 311(b)(2)(A) of the Clean Water Act.
Methods of Remediation
The following approaches are used to remediate hazardous liquid spills into surrounding soils:
- Low-Temperature Thermal Desorption (LTTD) – also known as low-temperature thermal volatilization, thermal stripping, and soil roasting –is an ex-situ remedial technology that uses heat to physically separate petroleum hydrocarbons from excavated soils.
- Vacuum trucks may be employed to vacuum concentrated oils from pools or puddles.
- Absorbing sponges or dry chemicals may be used to soak up excess oil.
- Bioremediation --The use of biological agents, such as bacteria or plants, to remove or neutralize contaminants – can help clean ground water contaminated with gasoline, solvents, and other contaminants. Often, the bacteria active in bioremediation are already present in the soil or aquifer, and the process takes place naturally. In some cases, however, the rate of bioremediation is too slow to effectively clean up a plume of contaminated water before it gets to a spring, well, lake, or stream. In those cases, the rate of bioremediation can sometimes be enhanced by adding a substance that acts like a fertilizer to make the bacteria grow and feed more rapidly.
- Gas – usually air or oxygen – may be pressurized and injected into wells installed within the saturated zone, to volatilize contaminants dissolved in groundwater, present as non-aqueous phase liquid, or sorbed to the soil matrix. Volatilized contaminants migrate upward and are removed, typically through soil vapor extraction. This method is most applicable for volatile organic contaminants in relatively moderate to high-permeability geologic materials.
- In situ flushing, also known as injection/recirculation or in situ soil washing, is the general injection or infiltration of a solution into a zone of contaminated soil/groundwater, followed by down-gradient extraction of groundwater and contaminants. This is followed by above-ground treatment and/or re-injection. Solutions may consist of surfactants, co-solvents, acids, bases, solvents, or plain water. Excellent understanding of the hydrogeologic regime is essential in employing this method, and this it is best applied to moderate to high-permeability soils. This process may be used for a variety of organic contaminants, including non-aqueous phase liquid, as well as some inorganic contaminants.
- In situ stabilization/solidification, also known as in situ fixation, or immobilization, is a process of alteration of organic or inorganic contaminants to an innocuous and/or immobile state, by injection of stabilizing agents into a zone of contaminated soil/groundwater. Contaminants are physically bound or enclosed within a stabilized mass (solidification), or their mobility is reduced through chemical reaction (stabilization). Excellent understanding of the hydrogeologic regime is essential in this process as well. This process is best applied to moderate to high-permeability soils and may be used for a variety of organic and inorganic contaminants.