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www.epa.gov/research
science   in   ACTION
INNOVATIVE RESEARCH  FOR A SUSTAINABLE FUTURE
     Innovative Capping Technology to Prevent the Migration of Toxic
     Chemicals from Contaminated Sediments
     Research Value:

     Contaminated sediments is a
     problem in many U.S. waterways.
     Nearly 40% of the rivers and
     streams in the U.S. are too
     polluted for fishing and
     swimming.  Contaminants in
     sediments involve both
     microorganisms and toxic
     chemicals. Many widespread
     persistent toxic chemicals are
     present in sediments, including
     polychlorinated biphenyls
     (PCBs), poly cyclic aromatic
     hydrocarbons (PAHs), and heavy
     metals. These chemicals can be
     released into the water above, and
     can bioaccumulate in the food
     web to levels in fish that pose a
     risk to the wildlife and humans
     that eat them. Fish advisories,
     warnings not to eat fish caught in
     our lakes and streams, have
     become increasingly common.

     Capping is a common strategy
     for decreasing the risk associated
     with contaminated sediments in
     lakes and streams. Historically,
     caps have been designed to
     physically isolate contaminated
     sediments and prevent the
     transport of contaminants from
     sediments into the water above
     them, to aquatic organisms, and to
     wildlife and humans, with sand
     caps being common. Questions
     remain concerning the
     effectiveness of traditional sand
     capping.  These questions include
     the vertical transport of
            contaminants through the sand
            cap to the overlying surface water.
            New innovative capping
            materials have been developed
            that may address some of the
            questions with traditional sand
            caps. One of these new
                            ®
            materials, Aquablok  is a clay-
            based polymer composite,
            designed to swell and form a
            continuous and highly
            impermeable barrier. Other
            technologies involve the use of
            "active" material such as
            activated carbon or organoclays
            to retard or sequester the
            contaminants as they migrate
            vertically through the cap.
              Applying capping materials with a
                    clamshell bucket
            Research Details:

            EPA land risk management
            researchers are leading efforts to
            determine if these innovations can
            fulfill their promise to better
            protect human and wildlife health.
Goals in evaluating these
innovative capping materials
include:

• Evaluate how the performance
  of each capping technology is
  affected by gas generation
  below the cap.
• Develop improved methods for
  collecting and measuring
  sediment gas generation.
• Evaluate the degree to which
  aquatic organisms affect cap
  performance.
• Investigate  how the presence of
  a cap affects the number and
  diversity of organisms in a
  contaminated area.
• Evaluate the physical stability
  of each type of cap, and the
  fate and transport of
  contaminants overtime.


Joint Research with Academia:
Anacostia River Capping Study
A field study at the Anacostia
River in Washington, B.C. was
conducted with EPA's  Southwest
Hazardous Substance Research
Center to evaluate the
                       (S)
performance  of an AquaBlok
cap compared to a sand cap and
unaltered sediment. The study
included an evaluation of the
physical stability of the cap, the
effect of the cap  on the
groundwater and sediment
interface, the impacts of the  cap
on aquatic organisms, and the
impact of these organisms on
cap performance. Results of the
study are available in the report,
           U.S. Environmental Protection Agency
           Office of Research and Development (ORD), National Risk Management Research Laboratory (NRMRL)
           Land Remediation and Pollution Control Division (LRPCD)

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Demonstration of the AquaBlok
Sediment Capping Technology.
   Studying sediment properties


Joint Research with EPA
Region and State: Chattanooga
Creek Cap Monitoring Study
EPA land risk management
researchers are working with
EPA Region IV and with the
Department of Environmental
Conservation in Tennessee to
monitor an installed AquaBlok
cap in a section of Chattanooga
Creek that has  seen decades of
industrial pollution from coal tar
and creosote.

Joint Research with EPA's
GLNPO and ACOE: Sorbent
Column Studies
EPA is working in cooperation
with the Great  Lakes National
Program  Office (GLNPO) and
the U.S. Army Corps of
Engineers (ACOE) to evaluate
various sorbents for possible use
on contaminated sites in the
Great Lakes area.  The ultimate
goal of this research is to refine
the design process for more
effective caps.

Joint Research with
Department of Defense (DOD):
Cap Evaluation Studies
EPA is working in integrated
collaborative efforts with the
U.S. DOD (which has programs
for environmental research and
environmental security), the
ACOE, and EPA's Regional
Offices to improve cap designs
and their cost effectiveness.
In other DOD-related efforts,
EPA has evaluated an innovative
bauxite cap for containing
mercury contaminated sediments,
and is currently evaluating the
impact of propeller wash on the
stability of sediment caps.
       Placing a reactive cap


Outcomes and Impacts:
Innovative capping technology
research is helping to provide
more options to reduce the risk to
humans and benthic organisms
from contaminated sediments.
This research is providing new
information and tools that are
being used by EPA's  Office of
Superfund Remediation and
Technology Innovation and
EPA's  regional staff to select the
most environmentally and cost
effective remediation techniques
at contaminated sediment sites.

Future research on capping and
other sediment remediation
projects will examine
incorporation of tools such as
Life Cycle Assessment (LCA)
into efforts for sustainable
sediment management.
                                                                        LAND RESEARCH PROGRAM
                                                                        WEB SITE: www.epa.qov/nrmrl/lrpcd
CONTACTS

Dennis Timberlake, Technical
Inquiries. 513-569-7547, EPA/
ORD/ LRPCD/SSMB
timberlake.dennis(@,epa.gov.

EdBarth, Technical Inquiries.
513-569-7669, EPA/ORD/
LRPCD/SSMB barth.ed(@,epa.gov

Roger Yeardley, Communications.
513-569-7548. EPA/ ORD/ LRPCD
veardlev.roger(@,epa.gov
REFERENCES

Evaluation of Sediment Agitation and
Mixing into the Surrounding Water
Column from Capping Activities at the
Wyckoff/Eagle Harbor Superfund Site,
EPA/540/R-05/013, July 2006.
http://www.epa. gov/ORD/NRMRL/pubs
/540r05013/540r05013.pdf

Demonstration of the AquaBlok
Sediment Capping Technology
(Innovative Technology Evaluation
Report) EPA/540/R-07/008, Sept. 2007.
http://www.epa. gov/ORD/NRMRL/pubs
/540r07008/540R07008.pdf
                                  National Risk Management Research Laboratory
                                  Land Remediation and Pollution Control Division
                                                   EPA/600/F-11/009
                                                      June 2011
                                                                                     www.epa.gov/nrmrl

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