A Citizen’s Guide to Soil Vapor 

Extraction and Air Sparging

What Are Soil Vapor Extraction And 

Air Sparging?

Both soil vapor extraction, or “SVE,” and air sparging 

extract (remove) contaminant vapors from below 

ground for treatment above ground. Vapors are the 

gases that form when chemicals evaporate. SVE 

extracts vapors from the soil above the water table by 

applying a vacuum to pull the vapors out. Air sparging, 

on the other hand, pumps air underground to help 

extract vapors from groundwater and wet soil found 

beneath the water table. The addition of air makes the 

chemicals evaporate faster, which makes them easier 

to extract with another technology, such as SVE. 

Both methods are used for chemicals that evaporate 

easily─like those found in solvents and gasoline. These 

chemicals are known as “volatile organic compounds,” 

or “VOCs.” 

How Do They Work?

Extraction:

SVE involves drilling one or more extraction wells into 

the contaminated soil to a depth above the water table, 

which must be deeper than 3 feet below the ground 

surface. Attached to the wells is equipment (such as 

a blower or vacuum pump) that creates a vacuum. 

The vacuum pulls air and vapors through the soil 

and up the well to the ground surface for treatment. 

Sometimes the ground must be paved or covered with 

a tarp to make sure that the vacuum does not pull air 

from above into the system. Pulling in clean air would 

reduce the efficiency of the cleanup. The cover also 

prevents any vapors from escaping from the ground to 

the air above.

Air sparging involves drilling one or more injection 

wells into the groundwater-soaked soil below the 

water table. An air compressor at the surface pumps 

air underground through the wells. As air bubbles 

through the groundwater, it carries contaminant vapors 

upward into the soil above the water table. The mixture 

of air and vapors is then pulled out of the ground for 

treatment using SVE.

Treatment:

Extracted air and contaminant vapors, sometimes 

referred to as “off-gases,” are treated to remove any 

harmful levels of contaminants. The off-gases are first 

piped from the extraction wells to an air-water separator 

to remove moisture, which interferes with treatment. 

The vapors are then separated from the air, usually by 

pumping them through containers of activated carbon. 

The chemicals are captured by the carbon while clean 

air exits to the atmosphere. (See A Citizen’s Guide to 

Activated Carbon Treatment [EPA 542-12-001.]). 

Filter materials other than activated carbon may be 

used. In a process called “biofiltration,” tiny microbes 

(bacteria) are added to break down the vapors into 

gases, such as carbon dioxide and water vapor.

Another option is to destroy vapors by heating them to 

high temperatures. 

How Long Will They Take?

Cleaning up a site using SVE or air sparging may take 

several years. The actual cleanup time depends on 

several factors. For example, cleanup may take longer 

where:

• Contaminant concentrations are high.

• The contaminated area is large or deep.

• The soil is dense or moist, which slows the 

movement of vapors.

Illustration of a combined air sparging and SVE system. These factors vary from site to site.
United States Office of Solid Waste and EPA 542-F-12-018

Environmental Protection Emergency Response September 2012

Agency (5102G) www.epa.gov/superfund/sites

www.cluin.org

Example

Both SVE and air sparging are 

being used to clean up several 

acres of contaminated soil and 

groundwater at the Vienna PCE 

Superfund site in West Virginia. 

Two dry cleaning facilities 

contaminated the area with PCE 

(also known as perchloroethene 

or “perc”), a solvent used to clean 

clothing, forcing the shutdown of 

the town’s drinking water wells.

In 2005, construction of the 

cleanup systems was completed 

and included 74 air sparging 

wells, 34 extraction wells, 

and four treatment buildings. 

The off-gases are piped to an 

air-water separator, followed by 

containers of activated carbon 

for treatment. By 2010, 1,618 

pounds of PCE had been 

removed and PCE concentrations had decreased by as much 

as 99% in some wells. EPA will 

continue to operate the systems 

and monitor PCE levels until 

cleanup objectives have been 

reached throughout the site. 

For More Information

For more information about 

this and other technologies in 

the Citizen’s Guide Series, 

visit:

www.cluin.org/remediation

www.cluin.org/products/

citguide

www.cluin.org/sve 

www.cluin.org/airsparging

NOTE: This fact sheet is intended solely as general information to the public. It is not intended, nor can it be relied upon, to create any 

rights enforceable by any party in litigation with the United States, or to endorse the use of products or services provided by specific 

vendors. The Agency also reserves the right to change this fact sheet at any time without public notice.

Are SVE And Air Sparging Safe?

When properly designed and operated, SVE and air sparging pose little 

risk to site workers or the community. Treatment of the vapors involves no 

harmful chemicals that must be transported to the site. Chemical vapors 

are contained from extraction to treatment so they cannot be accidentally 

inhaled by anyone nearby. Only clean air that meets air quality standards 

is released. The air released to the atmosphere following treatment 

may be sampled to make sure all harmful vapors have been removed 

or destroyed. 

How Might It Affect Me?

Area neighborhoods may experience some increased truck traffic as the 

equipment for SVE or air sparging is delivered and later removed. Installation 

of the systems involves the use of drilling rigs and sometimes other heavy 

machinery to install wells, blowers, and treatment equipment. Sheds or 

larger buildings may be built to house the treatment systems, keeping any 

noise to a minimum. Workers will visit these systems regularly to ensure they 

are working.

Why Use Soil Vapor Extraction And Air Sparging?

SVE and air sparging are efficient ways to remove VOCs above and below the 

water table. Both methods can help clean up contamination under buildings, 

and cause little disruption to nearby activities when in full operation. SVE and 

air sparging are often used together. SVE and air sparging are being used 

or have been selected for use at approximately 285 and 80 Superfund sites, 

respectively. 

Above-ground treatment system includes two tanks of 

activated carbon.

Pipes transport vapors from the 

underground SVE extraction well 

to treatment.