Community Guide to |j|p
In Situ Carbon Amendments
for Groundwater







What Are In Situ Carbon
Amendments?

In situ carbon amendments are materials that are
placed underground to remove contamination from
groundwater. The amendments are made up of small
particles of coal, wood, nutshells or other carbon-rich
materials that have been heated to increase the
surface area of the particles. Reactive materials such
as iron particles or peroxide may be added to help
destroy some types of contaminants. Microbes (very
small organisms naturally found in the environment)
may also be added to promote destruction. (See
Community Guide to Bioremediation.) The technology
is "in situ" because cleanup is conducted in place,
without having to pump out groundwater for treatment
above ground. In situ carbon amendments most often
are used to treat groundwater contaminated with
petroleum products and solvents.

How Do They Work?

The amendments treat contaminants through two
processes: adsorption and degradation. Adsorption
takes place when contaminants stick to the carbon
particles. (See Community Guide to Granular
Activated Carbon Treatment.) Degradation occurs
when reactive materials or naturally-occurring
microbes cause chemical and biological reactions

that change the contaminants to less harmful
substances. The specific reactive materials selected
depend on conditions at the site.

The mixture of amendments is placed underground
to directly contact contaminated soil and
groundwater. Most often, amendments are injected
through vertical pipes or pipes that are angled to
reach contamination beneath objects on the ground
surface. Trenches also can be dug and filled with the
amendments, or earthmoving equipment can mix
them into the soil. The amendments usually form a
reactive zone across the flow of the contaminated
groundwater so that the water flows through it.
High-pressure injection, or fracturing, can help
place amendments in dense clay or silty soil. (See
Community Guide to Fracturing for Site Cieanu, .)

How Long Will It Take?

It may take several months to a few years to complete
a cleanup using in situ carbon amendments. The
cleanup time will depend on several factors that vary
from site to site. For example, cleanup with in situ
carbon amendments will take longer where:

•	Concentrations of contaminants are high.

•	The contamination source has not been completely
removed.

Carbon
Amendments

Carbon amendments can be injected underground to treat fuel from leaking tanks.

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Example

Water supply wells near
the East 67th Street Ground
Water Plume Superfund site
In Texas were contaminated
by a release in the 1980s
of chemicals, including
solvents, from a former
chemical facility. New water
supply wells were installed in
clean areas, and soil vapor
extraction and bioremediation
were used to treat shallow
source area contamination.

In 2017, carbon amendment
was injected in the ground
beneath the street to
treat groundwater and to
prevent the further spread
of contaminants. The
reactive zone formed by the
amendment is 300 feet long
and extends 85 to 100 feet
below the ground surface.
Contaminated groundwater is
treated as it flows through the
zone, which is expected to be
effective for about 15 years.
After that, additional injections
may be needed. Groundwater
is sampled before and after
flowing through the reactive
zone to monitor performance.
Within the first three
years, data showed that
contaminant concentrations
met treatment goals.

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For More Information

•	About this and other
technologies in the
Community Guide Series,
visit: https://clu-in.org/cguides
or https://clu-in.org/
remediation/

•	About use of cleanup
technologies at a Superfund
site in your community,
contact the site's community
involvement coordinator or
remedial project manager.
Select the site name from
the list or map at http://
www.epa.gov/superfund/sites
to view their contact
information.

L.	A

Injecting amendments at angle underground.

•	The contaminated area is large or hard to reach.

•	The soil requires fracturing.

Are In Situ Carbon Amendments Safe?

In situ carbon amendments do not pose a threat to site workers or to
your community when properly handled. Because contaminated soil and
groundwater are cleaned up underground, workers are not exposed to
contamination. Treated water is analyzed regularly to ensure that the carbon
amendments continue to work properly.

How Might They Affect Me?

You may notice increased truck traffic as the equipment and materials are
delivered to the site. You might also hear construction noise as amendments
are injected or mixed, or as trenches are dug. Dust from site activities is
controlled by spraying water and covering stockpiled soil and materials.

Why Use In Situ Carbon Amendments?

In situ carbon amendments can treat a wide variety of contaminants
and usually work very quickly. Injecting amendments can help reach
groundwater contamination at facilities where buildings, paving and other
structures block large treatment equipment. Once amendments are in
place, treatment occurs without disrupting activities on the property, and
requires little energy or maintenance. In situ carbon amendments have
been selected for use at several Superfund sites and other cleanup sites
across the country.

NOTE: This fact sheet is intended solely as general information to the public. It is not intended, norcanitbe
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.

Office of Land and Emergency Management (5203P) | EPA-542-F-21-012 | 2021 | www.clu~in.org

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