EPA Soil Flush

EPA Soil Flush - United States Environmental Protection...

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- 1 - United States Solid Waste and EPA 542-F-96-006 Environmental Protection Emergency Response April 1996 Agency (5102G) A Citizen’s Guide to In Situ Soil Flushing A Quick Look at In Situ Soil Flushing • Injects a washing solution into unexcavated soils to flush out contaminants. • Is most effective on soils with low silt or clay content. • Requires the drilling of injection and extraction wells on-site. • Is a transportable technology that can be brought to the site. • Requires greater understanding of the site’s geology than some other technologies. Printed on Recycled Paper Technology Innovation Office Technology Fact Sheet What is in situ soil flushing? In situ soil flushing is an innovative treatment tech- nology that floods contaminated soils with a solu- tion that moves the contaminants to an area where they are removed. “In situ”—meaning “in place”— refers to treating the contaminated soil without dig- ging up or removing it. The specific contaminants in the soil at any particu- lar site determine the type of flushing solution need- ed in the treatment process. The flushing solution is typically one of two types of fluids: 1) water only ; or 2) water plus additives such as acids (low pH), bases (high pH) or surfactants (like detergents). Water is used to treat contaminants that dissolve easily in water. An acidic solution is a mixture of water and an acid, such as nitric acid or hydrochloric acid. Acidic solutions are used to remove metals and organic contaminants, such as those typically found in battery recycling or industrial chrome plat- ing processes. For example, zinc contamination— which can result from plating operations—would be treated with an acidic solution. A basic solution is a mixture of water and a base, such as sodium hydroxide. (Ammonia is an example of a base com- monly used in households.) Basic solutions are used to treat phenols and some metals. A surfactant can be a detergent or emulsifier. Emulsifiers help mix substances that normally do not mix such as oil and water. For this reason, surfactant solutions are effec- tive at removing oily contaminants. Researchers also are investigating the use of water plus organic solvents as a flushing solution. Organic solvents such as ethanol are used to dissolve certain contaminants that water alone cannot dissolve. How does it work? Figure 1 on page 2 provides an illustration of one type of in situ soil flushing process. The process be- gins with the drilling of injection wells and extrac- tion wells into the ground where the contamination has been found. The number, location, and depth of the injection and extraction wells depend on many geological factors and engineering considerations.
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EPA Soil Flush - United States Environmental Protection...

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