<>EPA
www.epa.gov/ord/lrp
science in ACTION
BUILDING A SCIENTIFIC FOUNDATION FOR SOUND ENVIRONMENTAL DECISIONS
LAND RESEARCH
PROGRAM
Research Guides Remediation of Contaminated Sediments
Impacted by Groundwater Discharge
Issue
The discharge of groundwater
into surface water may influence
the concentrations and
availability of contaminants in
sediments. There are three
predominant pathways by which
groundwater may affect the
characteristics of contaminated
sediments:
• Direct contribution of
contaminants from the
discharge of contaminated
groundwater
• Indirect influence on existing
contaminants due to geologic
and chemical processes that
change the properties of
sediments and contaminants
• Indirect influence on existing
contaminants due to the
influence of groundwater
discharge on biological (e.g.,
microbial) processes that
transform or degrade
contaminants
Ground water can act as a conduit
for dissolved pollutants and
sediment constituents. With an
enhanced understanding of
groundwater discharge to surface
water systems, scientists can
improve estimates of long-term
contaminant loads in sediments
and develop better management
practices to control human and
ecosystem exposure to
contaminated sediments.
Science Objective
The Land Research Program in
EPA's Office of Research and
Development is conducting field-
based research to:
• Develop methods to best
characterize hydrologic and
chemical processes at the
groundwater / surface water
(GW/SW) interface
• Understand the role of
groundwater flux on sediment
processes governing
contaminant speciation and
mass
This research entails
characterization of water and
solids within the GW/SW
transition zone to explain
processes that occur during
physical contact between
groundwater and sediments.
These measurements are
conducted to capture the spatial
and temporal variability that is
commonly encountered in these
natural systems.
The overarching research goal is
to develop a framework for risk
characterization at contaminated
sites, which will assist risk
managers in selecting remediation
strategies to best manage human
and ecosystem exposure to
contaminated sediments impacted
by groundwater discharge.
Application / Impact
The outcome of this research
provides EPA with practical
knowledge to guide site
characterization and remediation
at sites where groundwater
discharge exerts short- and long-
continued on back
U.S. Environmental Protection Agency
Office of Research and Development
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&EPA
www.epa.gov/ord/lrp
science in ACTION
BUILDING A SCIENTIFIC FOUNDATION FOR SOUND ENVIRONMENTAL DECISIONS
LAND RESEARCH PROGRAM
con l i n u eil from fro n I
term influence on sediment
contamination.
Field and laboratory studies
conducted by the Land Research
Program have enabled EPA to
better predict the mobility,
bioavailability, and fate of
contaminants in sediments, and to
develop effective remediation
strategies.
Research accomplishments
include:
• Identification of links
between groundwater
discharge and sediment
contamination with emphasis
on arsenic, lead and zinc
• Development of new
approaches to identify spatial
variability of groundwater
discharge into surface-water
systems using direct
measurements and cost-
effective surrogate measures
• Use of research findings by
EPA Region 1 to identify the
impact of groundwater
discharge on metal
contamination in sediments,
and to select cost-effective
remedies to manage
contaminant inputs at two
Superfund sites.
Groundwater discharge may serve
as a long-term source of
contaminants to sediments within
a watershed and/or may govern
processes controlling the
properties of existing
contaminants. Design of
appropriate remedies that account
for the influences of groundwater
provides the basis for more
effective remedies to manage
risks to human and ecosystem
health.
REFERENCES
Lien, B. K. 2006. Development and
Demonstration of a Bidirectional Advective Flux
Meter for Sediment-Water Interface. EPA Report,
U.S. Environmental Protection Agency,
Cincinnati, OH, EPA/600/R-06/122.
http ://www.epa. gov/nrmrl/pubs/600r06122/600r06
122.pdf
Ford, R. G., Wilkin, R. T., Hernandez, G. 2006.
Arsenic cycling within the water column of a small
lake receiving contaminated ground-water
discharge. Chemical Geology, 228(1-3): 137-155.
Wilkin, R. T., Ford, R. G. 2006. Arsenic solid-
phase partitioning in reducing sediments of a
contaminated wetland. Chemical Geology,
228(1-3): 156-174.
Ford, R. G., Wilkin, R. T., Scheckel, K. G., Paul,
C. J., Beck, F., Clark, P., Lee, T. 2005. Field Study
of the Fate of Arsenic, Lead, and Zinc at the
Ground-Water/Surface-Water Interface, EPA
Report, U.S. Environmental Protection Agency,
Cincinnati, OH, EPA/600/R-05/161.
http://www.epa.gov/ORD/NRMRL/pubs/600R051
61/600R05161.pdf
Ford, R. G. 2005. The Impact of Ground Water-
Surface Water Interactions on Contaminant
Transport with Application to an Arsenic
Contaminated Site, EPA Environmental Research
Brief, U.S. Environmental Protection Agency,
Cincinnati, OH, EPA/600/S-05/002.
http://www.epa.gov/ORD/NRMRL/pubs/600s0500
2/epa_600_s05_002.pdf
CONTACTS
Robert Ford, EPA's National Risk Management
Research Laboratory, 513-569-7501,
ford.robert(g),epa.gov
Bob Lien, EPA's National Risk Management
Research Laboratory, 513-569-7443,
lien.bob(g!epa. gov
Steven Acree, EPA's National Risk Management
Research Laboratory, 580-436-8609,
acree.steven(g!epa.gov
OCTOBER 2008
U.S. Environmental Protection Agency
Office of Research and Development
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