Technology Provides for Quick, Easy Clean-up of Gasoline Leaks
In recent months the cleaner-burning, pollution-fighting gasoline additive Methyl Tertiary-Butyl Ether (MTBE) has come under scrutiny as a result of gasoline leaking from underground gasoline containment systems. Because it is more water soluble, MTBE generally can be transported faster and farther in soil and water than other gasoline components. In general, higher concentrations and longer subsurface plumes can be observed more often with MTBE than are seen with other gasoline compounds.
Some claim that MTBE can not be cleaned-up utilizing the approaches used to clean-up typical gasoline spills and leaks today. This is untrue. MTBE in groundwater can be quickly, cost-effectively and efficiently remediated using the same technologies that are currently used to clean-up any gasoline leak or spill. In addition, because of its higher volatility, MTBE tends to evaporate more quickly from soil and surface waters. Today, there are many clean-up technologies available to remove gasoline components, such as MTBE from soil and groundwater, including:
- Soil Vapor Extraction. This technology pulls air through the soil to extract contaminants. MTBE is not easily adsorbed in soil and will vaporize readily, thus it can be readily removed.
- Air Sparging. This technique pumps air through the groundwater to stimulate biodegradation and strip contaminants from the groundwater into the air stream.
- In-situ Oxidation. MTBE can be removed from water sources by relying on the capacity of certain chemicals (e.g. hydrogen peroxide combined with iron) to rapidly oxidize organic molecules in water.
- Bioremediation. Under natural conditions, MTBE biodegrades more slowly than other gasoline constituents; however, recent studies show that under enhanced conditions (e.g., addition of oxygen, microbes, and/or nutrients to the soil/groundwater), MTBE will biodegrade much more rapidly.
- Flushing (Pump and Treat). This technology pumps groundwater to the surface and treats it using air stripping, activated carbon, or advanced oxidation. Its high solubility and low soil adsorbency enable MTBE to be readily flushed from the groundwater.
The cost of treating drinking water containing MTBE varies depending on the flow rate of the system, the influent concentration of MTBE in the water, and the level to which MTBE must be treated in the delivered water. In general, the cost to remediate gasoline with MTBE is comparable to the cost of treating conventional gasoline without MTBE, particularly for equivalent plume sizes. Moreover, the costs for applying these technologies are generally well below alternative water supply and/or replacement costs.
If gasoline components, such as MTBE, enter water supplies, there are several accepted drinking water treatment technologies available to cost effectively remove them from water. They include:
- Air Stripping. In an air stripper, contaminated water flows down a column filled with packing material while upward-flowing air strips the contaminant from the water.
- Activated Carbon. This widely used technology removes multiple organic compounds including MTBE by pumping water through a bed of activated carbon onto which contaminants adsorb. Many homeowners use small carbon canisters to remove a variety of contaminants from private wells.
- Advanced Oxidation. This technology is based on oxidation of contaminants using appropriate combinations of ultraviolet light, chemical oxidants, and catalysts.
Releases of gasoline into the environment can adversely impact drinking water resources, and require rapid response. The presence of MTBE in gasoline increases the need for adequate leak prevention and prompt clean-up of gasoline spills. However, commercially available remediation efforts, such as air stripping, advanced oxidation and granulated activated carbon processes, can be effectively used with strategies and treatment technologies to quickly and cost-effectively remove gasoline with or without MTBE from impacted water resources.