SEPA
United States
Environmental Protection
Agency
Office of Superfund Remediation and Technology Innovation
EPA 542-F-19-003	October 2019 Update
Climate Resilience Technical Fact Sheet:
Contaminated Sediment Sites
In June 2014, the U.S. Environmental Protection Agency (EPA) released the U.S. Environmental Protection Agency Climate Change
Adaptation Plan.1 The plan examines how EPA programs may be vulnerable to a changing climate and how the Agency can
accordingly adapt in order to continue meeting its mission of protecting human health and the environment. Under the Superfund
Program, existing processes for planning and implementing site remedies provide a robust structure that allows consideration of
climate change effects. Examination of the associated implications on site remedies is most effective through use of a place-based
strategy due to wide variations in the hydrogeologic characteristics of sites, the nature of remediation systems operating at
contaminated sites, and local or regional climate and weather regimes. Measures to increase resilience to a changing climate may be
integrated throughout the Superfund process, including feasibility studies, remedy designs and remedy performance reviews.
As one in a series, this fact sheet addresses
the climate resilience of Superfund remedies
at sites with contaminated sediment. It is
intended to serve as a site-specific planning
tool by (1) describing an approach to
assessing potential vulnerability of a
sediment remedy, (2) providing examples of
measures that may increase resilience of a
sediment remedy, and (3) outlining steps to
assure adaptive capacity of a sediment
remedy as climate conditions continue to
change. Concepts described in this tool may
also apply to site cleanups conducted under
other regulatory programs or through
voluntary efforts.
Cleanup at many sites involves remediating contaminated aquatic
sediment - the clay, silt, sand and organic matter at the bottom of or
along the banks of rivers, lakes, estuaries, harbors or other surface water
bodies. Common sediment remediation technologies are dredging or
excavation with off-site treatment or disposal, capping to isolate
contaminated sediment, and application of amendments that bind or
destroy the contaminants.2 Excavation is similar to dredging but includes
partial dewatering of the sediment. Dewatering is accomplished by
diverting water from the targeted area of a water body or constructing a
coffer dam around the area, thereby allowing use of conventional
construction equipment to remove the contaminated sediment.
In situ capping involves placing clean material on top of contaminated
material remaining in place on a water body floor or at adjacent areas,
which are often situated within the site's floodplains. In some cases, it includes a habitat layer designed to mimic the
native sediment and promote recovery of benthic communities. In a reactive cap, the isolation layer includes an
amendment such as an organoclay or activated carbon mat that binds or sequesters contaminants exiting the
sediment pore water and thereby prevents contaminant release to surface water. Other in situ remedies involve
monitored natural recovery (MNR) or enhanced MNR (EMNR). MNR relies on the site's naturally occurring physical,
chemical and biological processes to contain, destroy or otherwise reduce bioavailability or toxicity of contaminants
in sediment. EMNR involves placing a thin layer of clean sediment or additives above contaminated sediment to
accelerate contaminant transformation to less toxic or bioavailable compounds.
Climate resilience planning for a sediment remedy generally involves:
(1)	Assessing vulnerability of the remedy's elements and site's
infrastructure.
(2)	Evaluating measures potentially increasing the remedy's resilience to a
changing climate.
(3)	Assuring the remedy's capacity to adapt to a changing climate, which
helps the remedy continue to be protective of human health and the environment (Figure 1).
Resilience: A capability to anticipate,
prepare for, respond to, and recover from
significant multi-hazard threats with
minimum damage to social well-being, the
economy, and the environment.3
Assess System
Vulnerability
Exposure
Sensitivity
Evaluate Measures to
Increase Resilience
Identification
Prioritization
Assure Adaptive
Capacity
Implementation
Of Measures
Periodic
Reassessment
Figure 1. Climate Change Adaptation Management

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Assessment of Sediment Remedy Vulnerability
Assessing a sediment remedy's vulnerability to the effects of climate
change involves:
•	Determining the remedy's exposure to climate or weather
hazards.
•	Determining the remedy's sensitivity to the hazards.
A climate change exposure assessment identifies particular hazards
of concern and characterizes exposure to those hazards in light of
various climate and weather scenarios. The hazards may arise
abruptly due to extreme weather events, such as:
•	Scour of a sediment cap or underlying sediment due to
increased surface water flow velocity or turbulence caused by an
intense storm.
•	Influx of urban or agricultural stormwater runoff into the
sediment containment or treatment zone due to prolonged or
intense rainfall or rapid snowmelt.
•	Entrance of additional waste or debris from upland or upstream sources due to flooding, intense wind or
landslide.
•	Increased water turbidity in a treatment zone due to high wind in shallow water or arrival of increased discharge
to the watershed.
•	Misinterpretation of sediment sampling conducted via passive
devices, which might be affected by short-term events such as
storms.5
Other climate-related hazards may arise gradually, such as:
•	Desiccation of an unsubmerged sediment cap due to sustained drought conditions.
•	Exposure of a riverine cap due to sustained decreases in channel flow.
•	Scour of a sediment cap due to sustained freeze conditions.
•	Increased interaction with groundwater due to more frequent heavy rainfalls generating more discharge.
•	A sustained change in the freshwater-saltwater boundary at a coastal site due to a rising sea level.
The hazards also may concern potential resuspension and transport of contaminated sediments during construction
of a remedy or its long-term operation. In near-shore lake and marine settings, sediment transport may be
particularly affected by wave energy flux, tidal energy flux, wind forced currents, and subsurface currents as well as
the topography of a water body floor.2 Other hazards may concern onsite or offsite anthropogenic stressors, such as
land development that removes vegetated windbreaks and other natural protective barriers or causes infill
subsidence in low-lying areas. Unchecked stormwater runoff in highly developed areas has the potential to increase
pollutant loads as well as enable sediment recontamination at a site. Evaluation of stormwater runoff volumes and
pollutant loadings in developed areas need to consider a wide range of rain conditions rather than only large storms.7
Dynamic information about climate and weather variabilities and trends across the United States is available from
several federal agencies to help screen potential hazards in a given spatial area and identify those of concern. Web-
based platforms and tools include:
•	U.S. Army Corps of Engineers (USACE) methods such as the Climate Hydrology Assessment Tool.
•	U.S. Geological Survey (USGS) resources such as StreamStats.
•	National Oceanic and Atmospheric Administration (NOAA) resources such as Digital Coast, Sea Level Trends and
Sea, Lake and Overland Surges from Hurricanes (SLOSH).
Information also may be available from state agencies, regional or local sources such as watershed and forestry
management authorities, non-profit groups and academia.
Vulnerability: The degree to which a system is
susceptible to, or unable to cope with, adverse
effects of climate change, including climate
variability and extremes. Vulnerability is a function
of the character, magnitude, and rate of climate
variation to which a system is exposed; its
sensitivity; and its adaptive capacity.3
Changing climate conditions include sustained
changes in average temperatures, increased heavy
precipitation events, increased coastal flooding,
increased intensity of storm surge, sea level rise
and increased wildfire severity.4 A vulnerability
assessment helps project decision makers:
•	Understand which conditions may change at a
site.
•	Understand how altered conditions may affect
the site remedy.
About one-half of recently selected sediment
remedies involve treatment via physical separation
processes. Of these, dewatering accounts for
about one-half and oil/water separation and
mechanical sorting account for the remainder.6
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A climate change sensitivity assessment for a sediment remedy evaluates the likelihood for the climate change
hazards of concern to reduce the remedy's effectiveness. Potential direct effects of hazards associated with an
extreme weather event include power interruption, physical damage, water damage and reduced accessibility. The
indirect effects include hazardous incidents such as a chemical spill or explosion as well as altered site conditions such
as denuded vegetation.
Repeated exposure to extreme weather events or gradual changes in the site's climate regime may affect the remedy
or site in additional ways. For example, sites subject to sustained sea level rise may experience slumping of banks,
increased sediment deposition in floodplains and littoral zones, and greater saltwater intrusion. Over time, a site may
experience other related changes such as a modification in its allowable use or an alteration of its ecosystem services.
Depending on the site and the implemented remedial technology, overall failures of the remedy components may
result in:
•	Recontamination of sediment due to escape of capped
material
•	Contamination of surface water due to incomplete binding or
sequestering of contaminants within a reactive cap's isolation
layer.
•	Migration of contaminants from sediment to groundwater via sediment pore water.
•	Transport of resuspended/contaminated sediment to downstream or inland areas that were previously
uncontaminated.
•	Contamination of upland sediment or soil due to escape of excavated sediment from holding areas or engineered
treatment cells.
•	Delayed recovery of benthic communities.
•	Loss of wetland or riparian vegetation used for treatment or local buffering.
•	Incomplete or excess dredging of sediment.
•	Unexpected and additional costs for repairing or amending
sediment caps, performing additional dredging or
excavation/dewatering, or upgrading onsite infrastructure
elements such as transportation corridors or equipment
storage areas.
Of the remedies selected for sediment sites in
fiscal years 2012 through 2014, about 44 percent
address polycyclic aromatic hydrocarbons, 44
percent address polychlorinated biphenyls, and
more than 75 percent address metals.6
Dredging or excavation of sediment is involved at
more than 80% of the large sediment sites known
as "Tier 1" sites, where remedial actions are
addressing more than 10,000 cubic yards or five
acres of contaminated sediment.6
A temporary armored cap was installed at the San Jacinto Waste Pits
National Priorities List (NPL) site outside Houston, Texas, in 2011 to
cover waste containing dioxins and furans. This coastal site near
Galveston Bay receives an average of 54 inches of rain annually and is
vulnerable to tides, winds, waves and currents resulting from extreme
weather conditions such as strong storms, flooding, tornadoes and
hurricanes. About 50 percent of the cap is submerged in the San
Jacinto River.
in 2017, the site experienced 500-year flood conditions due to
Hurricane Harvey. Post-hurricane assessment indicated damage to
submerged as well as above-water portions of the cap, including its
geotextile layer and rock armor. About 1,000 tons of rock was placed in
36 damaged areas to temporarily armor the cap.
The remedy selected later in 2017 involves removal and offsite disposal
of material in the existing waste impoundments and MNR in an area
with low levels of contamination. Selection of the remedy considered
Galveston Bay's predicted 2.1 feet rise in sea level by 2100 as well as
USAGE hydrodynamic models of the site during past storm and
hurricane conditions. Modeling of remedial alternatives involving
waste caps projected significant erosion of cap armor under combined
hurricane and flood conditions.
Repair of the Sari Jacinto Waste Pits cap armor following
Hurricane Harvey.
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Vulnerable points of a sediment remedy due to extreme weather events may concern the remedy's submerged
components, its upland components, or site infrastructure critical to the remedy's construction, monitoring and
operation (Table 1). For example, reduced access to a site due to flooding of access roads could delay critical post-
storm inspection of a sediment cap.
Table 1. Considerations for Sensitivity Assessment of a Sediment Remedy
Potential Vulnerabilities Due to Extreme Weather
Examples of Remedy Components
Physical
Damage
Water
Damage
Power
Interruption
Reduced
Access
Submerged
Components
Geotextile layer(s) and armor of an in situ cap
~


~
Activated carbon in the insulation layer of a
reactive cap
~



Clean sediment layer overlaying contaminated
sediment for EMNR
~



Upland
Components
Dikes enclosing an engineered unit that stores
dredged or excavated material
~


~
Bank or slope stabilization structures such as
riprap revetment, steel nets or terrace stoplogs
~
~

~
Subsurface barriers made of cement slurry or
sheet piles
~
~

~
Site
Operations
and
Infrastructure
Temporary piers or water containment booms
~



Barges and tugs used to dredge contaminated
sediment
~
~

~
Exposed construction machinery and vehicles
~
~

~
Monitoring equipment
~
~
~
~
Sediment dewatering and treatment facilities
~
~
~
~
Fencing and signs for controlling access or use
~



Access roads
~


~
Buildings, sheds or housing
~
~
~
~
Liquid fuel storage units
~
~

~
Water supplies
~
~
~
~
Techniques for assessing potential vulnerability of a sediment remedy may include:
•	Collecting qualitative information such as photographs of submerged or upland components and current field
conditions.
•	Extrapolating quantitative data documented in resources such as NOAA or USGS mapping systems.
•	Modeling that uses predictive weather and climate data, through use of conventional software or commercially
available risk assessment software for engineered systems.
•	Developing site-specific maps and matrices that can aid decision-making.
Detailed information about climate-related vulnerability assessment and access to associated tools is provided in
resources such as the:
•	U.S. Climate Resilience Toolkit for exploring hazards and
assessing vulnerability and risks.
•	Climate Change 2014: Impacts, Adaptation and Vulnerability
report from the Intergovernmental Panel on Climate Change,
which includes a chapter (19) on assessing emergent risks and
key vulnerabilities.
More examples of relevant tools and other
resources are described online at Superfund
Climate Resilience: Vulnerability Assessment.
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As an illustration, Figure 2 highlights results of a preliminary vulnerability assessment for a sediment remedy currently
in place at a Superfund site. The illustration identifies potential disruptions to the remedy components due to
extreme weather events and provides a sample structure for documenting high-priority resilience measures that
could be implemented in the near term. Planning tools such as this also may be used to build additional adaptive
capacity over time.
This sample cleanup scenario involves a 50-acre Superfund site in an industrial area situated on a Mid-Atlantic shoreline.
Contaminants remain from past onsite disposal of industrial waste, including contaminated sludge that was disposed of in an
estuarine wetland. The soil, sediment and groundwater contaminants include metals, polynuclear aromatic hydrocarbons,
dioxins and pentachlorophenol and associated dense non-aqueous phase liquid (DNAPL).
The remedy involves MNR in a portion of the wetland, sludge removal from other parts of the wetland via dredging, a gravel
cover for contaminated soil in the former disposal area, in situ solidification/stabilization of DNAPL-contaminated soil, and a
groundwater collection system with supporting storm sewer upgrades. Following onshore solidification via cement mixing, a
portion of the dredged sediment will be used to cover a highly contaminated area of the river.
The majority of the site is within a 100-year floodplain and its elevation currently ranges from sea level to 9.5 feet above mean
sea level. Public information sources indicate that potential hazards for this scenario include flooding due to storm surge and
high tides, partial inundation due to sea level rise, and high winds associated with hurricanes. For example, predictions of sea
level rise in the area estimate a rise of 3.9 to 8.9 feet by the year 2100. In combination with site-specific data existing in
materials such as site investigation reports and the Superfund record of decision, professional judgment is used to identify and
prioritize resilience measures for this remedy.
Potential Points of
Potential System Disruption Due to
Extreme Weather
Resilience Measures for
System Vulnerability
Physical
Damage
Water
Damage
Power
Interruption
Reduced
Access
High-Priority
Vulnerabilities
Submerged or
Solidified sediment layer
of cap placed within the
river
•



Use predictive storm surge data
to model potential wave- and
tide-related scour
Subsurface
Components
Wells for groundwater
collection or monitoring
0


0


Sheet-pile vertical barrier
for groundwater control
0





Layer of gravel covering
contaminated soil
•



Maximize thickness of the
gravel layerto prevent water-
related erosion
Aboveground
Components
Leachate collection system
for soil cover
•



Size the leachate evaporation
pond to hold increasing
generation of leachate
Containment area storing
dredged sediment
•



Enclose the area with an
earthen berm to protect it from
stormwater runoff

In situ soil/cement mixing
area
•



Construct a bulkhead to protect
the area from storm surge

Water containment booms
€


0


Barge used for sediment
dredging
C


c

Site
Operations
and
Infrastructure
Sediment dewatering
equipment
•


c
Construct wind- and water-
resistant housing for the
equipment
Machinery and trucks used
to transfer material offsite
0


0


Liquid fuel storage units
•


c
Relocate and anchor the units
on higher ground

Connection to municipal
sewage system
c


0

^ high priority

medium priority

0 low priority
Figure 2. Illustrative Superfund Site Scenario: Vulnerability Assessment Results and Prioritized Adaptation Measures
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Evaluation of Potential Climate Resilience Measures
Results of a vulnerability assessment may be used to develop a
strategy for increasing a contaminated sediment remedy's resilience
to a changing climate and extreme weather events. Development of
the strategy entails:
•	Identifying resilience measures potentially applying to the
hazards of concern under various climate and weather scenarios.
•	Prioritizing resilience measures for specific components of the rem
Identification of potential resilience measures involves screening of ste
remediation components, provide additional barriers to protect the coi
components or alert project personnel of remedy compromises (Table
Some of the measures may address more than one climate or
weather scenario. For example, installing tie-down systems for
metal sheds that house remediation equipment would reduce
likelihood for the structures to be turned over or carried away by
moving floodwater or intense wind. Other measures could address
multiple components of a remedy. Constructing vegetated berms
outside the perimeter of a sediment cap, for example, could
protect the cap from stormwater crossing the site while protecting an adjoining wetland from airborne debris carried
by intense wind. Yet other measures could be scaled up to address multiple hazards. One example is the rock layer
typically used to armor a sediment cap from adjacent surface water; extending the armor length to the cap's full
perimeter would protect the cap from upland stormwater runoff as well as storm surge.
Measures to prevent erosion on the banks of surface water bodies
due to intense rainfall, rapid snowmelt, or intense wind may involve
installing "hard" armor such as stone riprap, "soft" armor such as
plants, or a combination of hard and soft armor.8 The U.S. Federal
Emergency Management Agency (FEMA) Engineering with Nature:
Alternative Techniques to Riprap Bank Stabilization describes a range
of alternatives to riprap, such as constructing engineered logjams, structural earth walls and brush mattresses.9
Construction or expansion of an onsite wetland is another important option. In addition to minimizing erosion along
shores or banks, wetlands can buffer the impacts of extreme wind, serve as floodwater storage areas, and filter
nonpoint source pollutants and sediment from stormwater runoff.10
For a newly identified remedy, selecting optimal measures during the design phase may maximize the remedy's
resilience to climate change hazards throughout the project life and help avoid costly retrofits. For example, designs
for an aquatic sediment cap may need to consider greater seasonal variation or sustained changes in conditions of the
given environment, such as water temperatures, depths or salinity. Environmental conditions such as these directly
affect the specific zone of bioturbation where significant physical mixing of sediment takes place; this biologically
active layer of surface sediment often drives the level of exposure to contaminants. Other design considerations
include assessing aquatic sediment movement due to future changes in tides, flooding, ice-related scour, oscillation of
lake elevation caused by sustained winds, storm-generated waves and currents, seismic-generated waves, and
earthquakes and associated landslides.
EPA's Contaminated Sediment Remediation Guidance for Hazardous Waste Sites recommends that contaminated
sediment site evaluations include assessing the potential impacts on sediment and contaminant movement caused by
a 100-year flood and other events or forces with a similar probability of occurrence (0.01 chance of occurring in a
year). It is important to consider whether the future 100-year flood is expected to differ from the historical 100-year
flood. Updated floodplain maps are available online from FEMA.11
6
Effective mitigation of climate change hazards for
a sediment remedy involves a site-specific
analytical approach rather than a broad
prescriptive plan.
edy.
ps that may be taken to physically secure
mponents, safeguard access to the
2).
In most cases, sediment dredging or excavation
have a relatively short duration. Scheduling of
these activities during times that are least likely to
experience extreme weather events may
significantly reduce a sediment remedy's
exposure.
Descriptions of engineered structures commonly
used in climate resilience measures are available
online at Superfund Climate Resilience: Resilience
Measures.

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Table 2. Examples of Climate Resilience Measures
Climate Change
Effects

Precipitation
Wind
Sea Level Rise
¦H Potential Climate Resilience Measures for a Contaminated Sediment Remedy
Submerged or
Subsurface
Components
~
~
~
~

Armor enhancement for in situ cap
Emplacing additional stone and gravel above a sand base layer to withstand scouring
forces of more intense waves and currents or more frequent development of ice jams
~
~
~


Amendment scheduling optimization
Applying materials intended for long-term contaminant binding or destruction far in
advance of (or after) seasons that typically bring low temperatures, high winds or high
precipitation, to maximize the time available for amendment-sediment mixing without
interference from conditions such as more intense tidal action or ice scour

~

~

Deposition controls
Building engineered structures such as dams to control the flow of flood-related deposition
in settings where increased underwater deposition enhances remedy performance
~
~
~
~

Modeling expansion for MNRand EMNR
Incorporating additional subsurface parameters and sampling devices in monitoring plans
to gauge the potential for resuspension of contaminated sediment under more extreme
weather and changing climate scenarios
Upland
Components

~
~
~

Armor on banks and floodplains
Installing fixed structures on or along the shoreline of flowing inland water or ocean water
to mitigate effects of erosion and protect site infrastructure; soft armor may comprise
synthetic fabrics and deep-rooted vegetation, while hard armor may consist of riprap,
gabions and segmental retaining walls

~
~
~

Coastal hardening
Installing structures to stabilize a shoreline and shield it from erosion through soft
techniques such as replenishing sand and vegetation or hard techniques such as building a
seawall or installing riprap

~
~
~

Constructed wetlands
Creating swamps, marshes, bogs or other areas vegetated with plants that are adapted
for life in saturated soils and therefore capable of reducing the height and speed of
floodwaters and providing buffer from wind or wave action and storm surge

~
~


Containment fortification
Placing riprap adjacent to a subsurface containment barrier located along moving surface
water, to minimize bank scouring that could negatively affect barrier integrity; for a
sediment cap vulnerable to storm surge, installing a protective vertical wall or armored
base to absorb energy of surges and prevent cap erosion or destruction

~



Ground anchorage
Installing one or more steel bars in cement-grouted boreholes (and in some cases
accompanied by cables) to secure an apparatus on a ground surface or to reinforce a
retaining wall against an earthen slope

~
~
~

Relocation
Moving selected system components to positions more distant or protected from potential
hazards; for flooding threats, this may involve elevations higher than specified in the
community's flood insurance study

~


~
Retaining wall
Constructing a structure (commonly of concrete, steel sheet piles or timber) that can
support earth masses having a vertical or near-vertical slope and consequently hold back
loose soil, rocks or debris

~
~


Tie down systems
Installing permanent mounts that allow rapid deployment of a cable system extending
from the top of a unit to ground surface
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Climate Change
Effects

Precipitation
Wind
Sea Level Rise
¦H Potential Climate Resilience Measures for a Contaminated Sediment Remedy
Remedy
Construction,
Operation and
Maintenance

~

~

Flood controls
Building one or more earthen structures (such as vegetated berms, vegetated swales,
stormwater ponds, levees or dams) or installing fabricated drainage structures (such as
culverts or French drains) to retain or divert floodwater spreading from adjacent surface
water or land surface depressions

~
~
~

Hurricane straps
Integrating heavy metal brackets that reinforce physical connection between the roof and
walls of a building, shed or housing unit
~
~
~
~
~
Plantings
Selecting native grasses, shrubs or trees that are tolerant of future weather and climate
scenarios where vegetation is needed for groundcover, shading, erosion control or wind
breaks
~
~
~
~
~
Power from off-grid sources
Constructing a permanent system or using portable equipment that provides power
generated from onsite renewable resources, as a primary or redundant po wer supply that
can operate independent of the utility grid when needed
~
~
~
~

Renewable energy system safeguards
Extended concrete footing for ground-mounted photovoltaic (PV) systems, additional
bracing for roof-top PV or solar thermal systems, and additional masts for small wind
turbines or windmills
~
~
~

~
Utility line burial
Relocating electricity and communication lines from overhead to underground positions,
to prevent power outages during and often after extreme weather events
~
~
~
~
~
Weather alerts
Using electronic systems that actively inform subscribers of extreme weather events or
provide updated Internet postings on local/regional weather and related conditions
The process of identifying and prioritizing potential measures for a sediment remedy at any phase of its
implementation may consider:
•	Unique topography of the site.
•	Age of any remedy components already in place.
•	Climate adaptation plans of local or regional agencies.
•	Existing infrastructure components such as navigation
channels, access roads, and power and water supplies.
•	Current and future use or development of the site as well as
adjacent properties.
•	Anticipated longevity of the potential measures.
•	Capital cost and operations and maintenance cost, as well as costs associated with potential repair or
replacement of remedy components due to weather- or climate-related damage in the future.
Prioritization of resilience measures may necessitate professional judgements regarding other aspects such as:
•	Critical versus non- or marginally-critical equipment, activities or infrastructure.
•	Minimum performance thresholds for remedial or site operations.
•	Levels of tolerance for operational disruptions.
Consideration of the materials deposited in
floodplains, whether called sediment or soil, is
critical to reducing risk in aquatic environments.
Effective control of the upland sediment/soil and
other upland source materials is also critical.
Accordingly, many measures to increase resilience
of an aquatic sediment remediation system
concern the adjoining upland environment.
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The Atlantic Wood Industries Superfund Site of Portsmouth, Virginia,
is located in and along the Southern Branch of the Elizabeth River tidal
estuary. Onsite contamination resulted from past use of the site for
commercial wood-treating and U.S. Navy waste disposal. Remediation
of the contaminated sediment involves dredging and excavation, with
onsite capping of dredged material that is consolidated behind two
offshore pile walls.
Measures to reduce the remedy's vulnerability to sea level rise and
storm surge-related flooding include:
•	Increasing design height of the offshore pile wall to 12.5 feet above
mean sea level, rather than the 10- to 12-foot height traditionally
used in the area.
•	Constructing grassed swales on upland sides of the offshore pile
walls to collect and convey stormwater runoff.
•	Designing the sediment cap to withstand continuing sea level rise;
NOAA-funded modeling conducted for the City of Portsmouth in
2013 predicts a rise of 1.0-1.7 feet by 2050 and 2.5-6.3 feet by 2100.
Adaptive Capacity: The ability of a system to
adjust to climate change (including climate
variability and extremes), to moderate potential
damages, to take advantage of opportunities, or to
cope with the consequences.3
One of two berms confining dredged sediment at the Atlantic
Wood Industries Superfund Site in Portsmouth, Virginia.
Assurance of Adaptive Capacity
Assuring the adaptive capacity of a contaminated sediment remedy
involves:
•	Implementing new or modified measures to increase climate resilience of the system or site operations and
infrastructure, as needed.
•	Establishing plans for periodically reassessing the system and site vulnerabilities, to determine if additional
capacity is needed as cleanup progresses and climate conditions change.
Sediment and surface water systems are dynamic. As a result, development of a robust conceptual site model (CSM)
during remedial investigation and frequent CSM updating thereafter
are critical in assuring a remedy's adaptive capacity. At most
Superfund sites involving contaminated sediment, completing a
sediment erodibility and deposition assessment (SEDA) is an
important part of developing or refining the CSM; the USAGE offers
detailed technical guidelines for conducting a SEDA.12
Information to help develop and maintain a robust
CSM is available in Environmental Cleanup Best
Management Practices: Effective Use of the
Project Life Cycle Conceptual Site Model.13
Climate resilience measures that are selected for implementation may be integrated into primary or secondary
documentation supporting existing containment systems. Key documentation includes monitoring plans, optimization
evaluations, five-year reviews and close-out planning materials. Resilience planning also may involve incorporating
specific requirements to be met in cleanup service contracts. In general, implementation of climate resilience
measures during early, rather than late, stages of the cleanup process might expand the universe of feasible options,
maximize integrity of certain measures and reduce implementation costs. Upfront planning also could enable the
measures to benefit the site's anticipated reuse. For example, climate-resistant plantings at an urban riverfront
property undergoing cleanup may be integrated into master plans for future redevelopment of the site for retail or
residential use.
Assurance of sufficient adaptive capacity is an iterative and flexible
process. It involves periodically reassessing the system's
vulnerability, monitoring the measures already taken and
incorporating newly identified options or information. Periodic
reassessments typically include verifying key data. For example,
predictions of colder winter temperatures and associated ice jams in channels connected to the Great Lakes could
prompt upgrades to the armor of an existing subaqueous cap. Established plans for the timing of vulnerability
reassessment may involve a predetermined schedule or use triggers such as an extreme weather event.
For systems already operating, increases in erosion
may signal the need to closely examine
components of the sediment remedy and
reevaluate vulnerabilities.
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Resources to help understand climate resilience planning and implementation are available through online
compendiums such as:
~	ARC-X (EPA's Climate Change Adaptation Resource Center), which provides online access to tools that help
communities anticipate, plan for and adapt to the changing climate.
~	The NOAA National Centers for Environmental Information, which provides multiple climate and weather datasets
and monthly summaries of U.S. temperatures and precipitation.
~	EPA's Addressing Climate Change in the Water Sector website, which provides information pertaining to climate
change impacts on water cycles and access to the State Water Agency Practices for Climate Adaptation Database.
The concepts, tools and examples provided in such compendiums may be used to tailor climate resilience planning for
a specific waste containment remediation system. Resources such as these also may serve as a guide in assuring that
the measures align with climate adaptation actions taken by relevant state, regional or local agencies. The Port
Authority of New York and New Jersey, for example, established a methodology for factoring projected future sea
level rise into its project design criteria.14 Over recent years, coastal
communities also have collaborated in using the Sea Level Affecting
Marshes Model (SLAMM) to develop specific plans for responding to
the issue of sea level rise.15
More examples of tools to help assure adaptive
capacity of a site remedy are described online at
Superfund Climate Resilience: Adaptive Capacity.
References
[Web access date: October 2019]
1	U.S. EPA; Climate Change Adaptation Plan; June 2014; https://www.epa.gov/greeningepa/climate-change-adaptation-plans
2	U.S. EPA; Contaminated Sediment Remediation Guidance for Hazardous Waste Sites; EPA-540-R-05-012; OSWER 9355.0-85; December 2005;
https://www.epa.gov/superfund/superfund-contaminated-sediments-guidance-and-technical-support
3	U.S. EPA; Vocabulary Catalog; Topics: Climate Change Terms;
https://ofmpub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do
4	U.S. EPA; Climate Change Indicators in the United States 2016; Fourth Edition; EPA 430-R-16-004; https://www.epa.gov/climate-indicators
5	U.S. EPA; Guidelines for Using Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites; https://clu-
in.org/download/contaminantfocus/sediments/Sediments-Passive-Sampler-SAMS_3.pdf
6	U.S. EPA; Superfund Remedy Report; Fifteenth Edition; EPA 542-R-17-001; July 2017; http://www.clu-in.org/asr/
7	Department of Defense Strategic Environmental Research and Development Program; Final Report: Assessment and Management of Stormwater
Impacts on Sediment Recontamination; SERDP Project ER-2428; April 2018; https://www.serdp-estcp.org/Program-Areas/Environmental-
Restoration/Conta mi nated-Sedi ments/Stormwater/ER-2428/ER-2428
8	U.S. EPA; Climate Ready Estuaries; Synthesis of Adaptation Options for Coastal Areas; EPA 430-F-08-024; January 2009;
https://www.epa.gov/cre/synthesis-adaptation-options-coastal-areas
9	FEMA; Engineering with Nature: Alternative Techniques to Riprap Bank Stabilization;
https://www.fema.gov/pdf/about/regions/regionx/Engineering_With_Nature_Web.pdf
10	Association of State Wetland Managers; Wetlands and Climate Change: Considerations for Wetland Program Managers; July 2015;
https://www.aswm.org/pdf_lib/wetlands_and_climate_change_consideratons_for_wetland_program_managers_0715.pdf
11	FEMA; Food Map Service Center; https://msc.fema.gov/portal/home
12	U.S. Army Corps of Engineers; Technical Guidelines on Performing a Sediment Erosion and Deposition Assessment (SEDA) at Superfund Sites; ERDC TR-
14-9; September 2014; https://semspub.epa.gov/work/HQ/174625.pdf
13	U.S. EPA; Environmental Cleanup Best Management Practices: Effective Use of the Project Life Cycle Conceptual Site Model; EPA 542-F-11-011; July
2011; http://www.clu-in.org/download/remed/csm-life-cycle-fact-sheet-final.pdf
14	The Port Authority of New York and New Jersey; Climate Resilience Design Guidelines. June 2018. https://www.panynj.gov/business-
opportunities/pdf/discipline-guidelines/climate-resilience.pdf
15	NOAA Digital Coast; Sea Level Affecting Marshes Model; https://coast.noaa.gov/digitalcoast/tools/slamm.html
To learn more about climate resilience at Superfund sites and access new information
and decision-making tools as they become available, visit:
www.epa.gov/superfund/superfund-climate-resilience
Contacts
Questions about climate resilience in EPA's Superfund Program may be forwarded to:
Carlos Pachon (pachon.carlos@epa.gov) or Hilary Thornton (thornton.hilary@epa.gov)
EPA is publishing this document as a means of disseminating useful information regarding approaches for assuring climate resilience. This document does not impose legally
binding reguirements on EPA, states, tribes or the regulated community and does not alter or supersede existing policy or guidance for contaminated site cleanup. EPA, federal,
state, tribal and local decision-makers retain discretion to implement approaches on a case-by-case basis.
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