v>EPA
United States	Office of Superfund Remediation and Technology Innovation
Environmental Protection
Agency	EPA 542-F-19-005	October 2019 Update
Climate Resilience Technical Fact Sheet:
Groundwater Remediation Systems
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
involving groundwater remediation systems.
It is intended to serve as a site-specific
planning tool by (1) describing an approach
to assessing potential vulnerability of a
groundwater system, (2) providing examples
of measures that may increase resilience of a
groundwater system, and (3) outlining steps
to assure adaptive capacity of a groundwater
system 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.
Groundwater remediation systems are common elements of
contaminated site cleanup projects and may function ex situ or in situ. Ex
situ processes often involve extracting contaminated groundwater from
an aquifer and transferring it to an aboveground system where the water
is treated; this approach is commonly known as "pump and treat" (P&T).
The groundwater may be extracted though a single well or a network of
wells equipped with pumps and interconnecting pipes. Treatment of the
extracted groundwater commonly involves removing contaminants by
way of activated carbon sorption, air stripping, filtration, ion exchange or
metals precipitation.
In contrast, in situ processes
often involve injecting
reagents into the subsurface
through one or more wells to promote desired biological or chemical
reactions in contaminated groundwater. Another common process
involves constructing one or more engineered subsurface cells that are
made of reactive materials and strategically positioned to intercept and treat a plume of contaminated groundwater.
Other in situ processes include air sparging, in-well air stripping and phytoremediation.
More than 80 percent of the Superfund site
remedies selected since 1982 address
contaminated groundwater. As of 2014,
about 50% of the groundwater remedies
involved in situ treatment.2
Climate resilience planning for a groundwater treatment system and
associated hydraulic controls generally involves:
(1)	Assessing vulnerability of the system's elements and associated site
infrastructure.
(2)	Evaluating measures potentially increasing the system's resilience to
a changing climate.
(3)	Assuring the system's capacity to adapt to a changing climate, which helps the cleanup 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
^Prlorltlzatlor^

Assure Adaptive
Capacity
ClmplementationN
Of Measures/
Periodic
Reassessment
Figure 1. Climate Change Adaptation Management

-------
Assessment of Groundwater Remediation System Vulnerability
Assessing a groundwater treatment system's vulnerability to the effects of
climate change involves:
•	Determining the system's exposure to climate or weather hazards.
•	Determining the system'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. Examples of potential hazards for a
groundwater remediation system include altered directions of groundwater
changes in the seasonal highs or lows of a water table.
The hazards may arise abruptly due to extreme weather events, which are
expected to occur at increasing intensities, durations and frequencies as
long-term climate conditions continue to change. Depending on a site's
location and attributes, hazards associated with an extreme weather event
may generate different outcomes and degrees of severity. For example, a
given amount of coastal precipitation could result in tidal floodwater that
infiltrates an existing stormwater management system at some sites,
inundates ground surfaces at other sites or overcomes storm defenses at
yet other sites.
Vulnerability assessment may consider factors that potentially exacerbate
the system's exposure and sensitivity, such as a long operating period.
Many groundwater treatment systems are designed to operate for 30 years or longer. Another future vulnerability
might concern the regional water infrastructure and water availability. For example, effluent from a P&T system may
need to be used as onsite or offsite non-potable water instead of discharged to surface water if sustained reductions
in regional precipitation are predicted. Other potential hazards may concern anthropogenic stressors, such as onsite
or nearby construction of structures with impervious surfaces that hinder natural infiltration of precipitation and
generate stormwater runoff.5 In addition to posing greater stormwater management challenges at a site, such runoff
adds a burden on a local publicly owed treatment works (POTW) that may already receive effluent from a P&T
system.
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. Geological Survey (USGS) resources such as the Groundwater Watch database.
•	National Oceanic and Atmospheric Administration (NOAA) information in the National Integrated Drought
Information System portal, including downloadable LIDAR data.
•	U.S. Army Corps of Engineers methods such as the Climate Hydrology Assessment Tool.
Information also may be available from state agencies, regional or local sources such as watershed and forestry
management authorities, non-profit groups and academia.
A climate change sensitivity assessment for a planned or operating groundwater remediation system evaluates the
likelihood for the climate change hazards of concern to reduce the system's effectiveness. Potential direct effects of
the hazards associated with an extreme weather event include power interruption, physical damage, water damage
and reduced accessibility. Potential indirect effects include petroleum oil or chemical spills, accidental fire, explosions
and ecosystem damage. System failures due to exposure to one or more hazards could result in:
•	Inadequate capture of targeted groundwater due to unexpected alteration of groundwater flow or aquifer
storage capacity, which may prompt a need to update the project's operating conceptual site model.
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
', higher influx of surface water and
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.
2

-------
•	Insufficient treatment of extracted groundwater due to compromises such as pressure loss or pump seizure.
•	Undesired biological or chemical reactions due to increased interaction of groundwater and surface water, which
could involve saltwater intrusion or pollutant-laden runoff.
•	Suspended operation of an active treatment system over a long period.
•	Unexpected and additional project costs for repairing or replacing the remediation system or site infrastructure
components such as power lines, maintenance corridors and buildings.
Vulnerable points of a groundwater remediation system due to extreme weather events may physically exist below,
at or above surface grades or involve the site's general operations and infrastructure (Table 1). For example, reduced
access to a site due to road flooding could disrupt critical activities such as periodic injection of reactive reagents into
the subsurface, delivery of fuels and other supplies and scheduled sampling of groundwater.
Table 1. Considerations for Sensitivity Assessment of a Groundwater Remediation System
Potential Vulnerabilities Due to Extreme Weather
Examples of System Components
Power
Interruption
Physical
Damage
Water
Damage
Reduced
Access
Groundwater
Extraction or
Containment
System
Wells

~

~
Extraction or aeration pumps
~
~
~
~
Vertical barriers

~

~
Pipe systems

~
~
~
Monitoring equipment
~
~
~
~
Aboveground
Components
of the
Treatment
System
Electrical controls
~
~
~
~
Transfer pumps
~
~
~

Pipe systems

~


Equipment powered by electricity, natural gas or
diesel, such as heaters, air blowers or generators
~
~
~

Flow-through treatment units such as carbon
vessels, clarifiers, and tray strippers
~
~
~

Chemical storage containers

~
~
~
Treatment residuals disposal system

~
~
~
Treated water discharge system
~
~
~

Site
Operations
and
Infrastructure
Buildings, sheds or housing
~
~
~
~
Electricity and natural gas lines
~
~
~
~
Liquid fuel storage and transfer
~
~
~
~
Water supplies
~
~
~
~
Exposed machinery and vehicles

~
~
~
Surface water drainage systems

~
~
~
Techniques for assessing potential vulnerability of a groundwater remediation system may include:
•	Collecting qualitative information such as photographs of system 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 summary site-specific maps, tables 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, and subsequently investigating the options and
prioritizing, planning and taking specific actions to increase resilience.
Examples of relevant tools and other
resources are described online at
Superfund Climate Resilience:
Vulnerability Assessment.
3

-------
• 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.
As an illustration, Figure 2 highlights results of a preliminary vulnerability evaluation for a groundwater remediation
system currently deployed at a Superfund site. The illustration identifies potential disruptions to the system 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 large Superfund site located on the outskirts of a metropolitan area along the Atlantic
coast, within a 1-meter sea level rise zone. Contaminants remain from the site's past use for light manufacturing and processing
of liquid industrial wastes received from other manufacturing and chemical firms. Remedial components include a subsurface
containment wall (containing soil/bentonite slurry to a depth of 10 feet), a sheet-pile retaining wall along an onsite creek, and a
groundwater P&T system with offsite discharge. The P&T system is situated in a downgradient portion of a 500-year floodplain
surrounding a 100-year floodplain where remediation equipment, material storage sheds and drums, and power lines exist.
Public information sources indicate that potential hazards for this scenario include flooding, high wind, storm surge and sea level
rise. 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
Power
Interruption
Physical
Damage
Water
Damage
nign-rnorrey
Vulnerabilities
Groundwater
Extraction or
Containment
System
Wells

o

O

Extraction pumps
•
•
•
•
Build well-head housing
Vertical barriers

o

o

Monitoring
equipment
•
•
•
•
Add a remote access system
Aboveground
Components
of the
Treatment
System
Electrical controls
•
•
•
•
Elevate above worst-case flooding
Transfer pumps
€
o
€


Pipe system

€



Electric equipment
•
O
•

Install a photovoltaic energy
system for backup power
Natural gas-driven
equipment
C
O
€


Flow-through units
€
O
€


Chemical storage
containers

•
C
•
Relocate to higher ground
Use tie down systems
Residuals disposal
system

o
€
€

Treated water
discharge system
C
o
€


Site
Operations
and
Infrastructure
Buildings, sheds, or
housing
•
•
•
O
Install hurricane straps
Electricity lines
•
c
•
•
Bury lines below ground surface
Liquid fuel storage
and transfer
C
c
•
•
Fortify concrete pads
Install anchor systems
Water supplies
€
€

•

Surface water
drainage systems

•
C
c
Construct vegetated swales
® high priority ® medium priority 0 low priority
Figure 2. Illustrative Superfund Site Scenario: Vulnerability Evaluation Results and Prioritized Adaptation Measures
4

-------
Evaluation of Potential Climate Resilience Measures
Results of a vulnerability evaluation may be used to develop a strategy for increasing a groundwater remediation
system'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 the given system.
Identification of potential resilience measures involves screening of steps Effective mitigation of climate change
that may be taken to physically secure the system, provide additional	implications for a groundwater
barriers to protect the system, safeguard access to the system or alert	remediation system involves a site-specific
project personnel of system compromises (Table 2). Some of the measures analytical approach rather than a broad
may address more than one climate or weather scenario. For example,	prescriptive plan,
integrating electronic devices that provide remote access to a groundwater
P&T system enables offsite workers to adjust or temporarily shut down operations during intense rainfall, high winds
or a sudden wildfire.
Some measures also may be scaled up to increase the resilience of co-located remediation systems, such as a nearby
soil vapor extraction operating in conjunction with a P&T system. Others may provide a degree of desired
redundancy. For example, enclosure of electronic cables within raceway fire barriers could provide electronic
equipment with additional heat- and fire-resistance in the event that an encroaching wildfire jumps an onsite
building's fire buffer.
For a new remediation system, selecting optimal measures during the design phase may maximize the system's
resilience to climate change implications throughout the project life and help avoid costly retrofits. Designs for a
groundwater remediation system could include specifications to meet particular vulnerabilities. For example, the
design could involve a deep well dewatering system to intermittently lower
the groundwater table within an extraction zone and reduce upwelling; a Descriptions of engineered structures
secondary containment system to capture hazardous liquids escaping from commonly used in climate resilience
flood-damaged treatment units; or structural reinforcement to protect
buildings from high winds. Optimal design models use the latest climate	Superfund Climate Resilience.
Resilience Measures.
predictions and a range of potential weather scenarios, in addition to
historic climate and weather data.
The process of identifying and prioritizing potential measures for a groundwater remediation system may consider:
Size and age of the system components and auxiliary equipment.
Complexity and anticipated duration of the groundwater remediation system.
Local or regional groundwater and surface water regimes and management plans.
Status of infrastructure components such as roads, power and water supplies.
Existing and critical means of access.
Relevant aspects of future land use or development.
Anticipated effectiveness and longevity of the potential resilience measures.
Capital cost and operations and maintenance (O&M) cost of the measures as well as costs associated with
potential system repair or replacement due to climate-related damage in the future.
Prioritization of resilience measures also may necessitate professional judgements regarding other aspects such as:
•	Critical versus non- or marginally-critical equipment, activities or infrastructure.
•	Minimum performance thresholds for system or site operations.
•	Levels of tolerance for operational disruptions.
5

-------
Table 2. Examples of Climate Resilience Measures
Climate Change
Effects
Groundwater
Extraction and
Control
System
Potential Climate Resilience Measures for System Components
Dewatering well system
Installing additional boreholes at critical locations and depths to maintain target
groundwater levels in the extraction/containment zone and reduce groundwater
upwelling without compromising the remediation system
Remote access
Integrating electronic devices that enable workers to remotely suspend pumping during
extreme weather events, periods of impeded access or unexpected hydrologic conditions
Well-head housing
Building insulated cover systems made of high density polyethylene or concrete for
control devices and sensitive equipment situated aboveground for long periods
Alarm networks
Integrating a series of sensors linked to electronic control devices that trigger shutdown
of the system, or linked to audible/visual alarms that alert workers of the need to
manually shut do wn the system, when specified operating or ambient parameters are
exceeded
Building envelope upgrades
Replacing highly flammable materials with (or adding) fire- and mold/mildew-resistant
insulating materials in a building, shed or housing envelope
Concrete pad fortification
Repairing concrete cracks, replacing pads of insufficient size or with insufficient
anchorage, or integrating retaining walls along the pad perimeter
Fire barriers
Creating buffer areas (land free of dried vegetation and other flammable materials)
around the treatment system and installing manufactured systems (such as radiant
energy shields and raceway fire barriers) around heat-sensitive components
Aboveground
Components
of the
Treatment
System
Flood controls
Building one or more structures to retain or divert floodwater, such as vegetated berms,
drainage swales, levees, dams or retention ponds	
Hazard alerts
Using electronic systems that actively inform subscribers of extreme weather events or
provide updated Internet postings on local/regional weather and related conditions
Hurricane straps
Integrating or adding heavy metal brackets that reinforce physical connection between
the roof and walls of a building, shed or housing unit	
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	
Relocation
Moving the system or its critical 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	
Tie down systems
Installing permanent mounts that allow rapid deployment of a cable system extending
from the top of a unit to ground surface	
Treatment water reuse
Reclaiming treated groundwater for the purpose of recharging the aquifer or meeting
onsite water needs such as irrigation, heating or cooling, wetlands replenishment or
wildlife/habitat support	
6

-------

Climate Change
Effects


Temperature
Precipitation
Wind
Sea Level Rise
Wildfires
Potential Climate Resilience Measures for System Components


~
~
~

Constructed wetlands
Creation of 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 a buffer from wind or wave action and storm surge


~



Pervious pavement
Replacing impervious pavement that impedes stormwater management with permeable
pavement in forms such as rubberized asphalt and brick pavers
Site
Operations
and
~
~
~
~
~
Plantings
Installing drought-resistant grasses, shrubs, trees and other deep-rooted plants to provide
shading, prevent erosion, provide wind breaks and reduce fire risk
Infrastructure

~



Riverbank armor
Stabilizing banks of onsite segments of a river (or susceptible stream) through installation
of "soft" armor (such as synthetic fabrics and/or deep-rooted vegetation) or "hard" armor
(such as riprap, gabions and segmental retaining walls)


~



Slope fortification
Anchoring a slope through placement of concrete or rock elements against a slope and
installing anchors and cables to secure the elements, or containing a slope through
placement of netting to hold back rock and debris
Assurance of Adaptive Capacity
Assuring the adaptive capacity of a groundwater remediation system
involves:
•	Implementing new or modified measures to increase resilience of
the system or site operations and infrastructure, as needed.
•	Establishing plans for periodically reassessing system and site
vulnerabilities, to determine if additional capacity is needed as
groundwater cleanup progresses and climate conditions change.
Climate resilience measures selected for implementation may be integrated into primary or secondary
documentation supporting existing groundwater remediation systems. Key documentation includes monitoring plans,
optimization evaluations, five-year reviews and close-out planning materials. For new projects, the measures also
may be integrated into the site's feasibility study and remedy design process. Remedy 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 selected measures to benefit the site's anticipated reuse. For example, armoring of an onsite
riverbank could shield a groundwater treatment plant from flooding hazards throughout its operating period while
beginning to stabilize the site for future industrial use.
Assurance of sufficient 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, ongoing updates to Federal Emergency
Management Agency (FEMA) floodplain maps may prompt implementation of flood-related measures that were
previously considered unnecessary. Established plans for the timing of vulnerability reassessment may use triggers
such as an extreme weather event or involve a predetermined schedule.
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
7

-------
Resources to help understand climate resilience planning and implementation are available through online
compendiums such as:
m 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 provide climate and weather data and
periodically updated maps on economic impacts of weather
disasters.
~	EPA's Addressing Climate Change in the Water Sector website,
which provides information pertaining to climate change
impacts on water cycles, demands, supplies and quality.
The concepts, tools and examples in such resources may be used to tailor climate resilience planning for a specific
groundwater remediation system. Such resources also may serve as a guide in assuring that the measures align with
climate adaptation actions taken by relevant federal, state, regional or local agencies, such as EPA's water reuse
action plan to ensure water availability and mitigate risks posed by droughts.6
Cleanup at the 1,400-acre Summitville Mine National Priorities List site in
Colorado has involved constructing a water treatment plant, a dam
impoundment storing mine-influenced water prior to its treatment,
groundwater interceptor trenches and a sludge disposal repository. Past
mining operations at this remote high-altitude site led to large-scale erosion
and metals mobilization that contaminate the Alamosa River.
The climate hazards include rapid snowmelts each spring and early summer,
intense rainfall events, cold temperatures and landslides. Resilience
measures have involved:
•	Constructing the water treatment plant at a position outside the 500-
year floodplain.
•	Elevating the spillway channel of the dam impoundment by three feet to
increase the dam's storage capacity by 16 percent.
•	Upgrading surface water culverts and conveyances to withstand a 100-
year snowmelt or 500-year, 24-hour rainfall event.
•	Removing standing dead wood to create a defensible fire space.
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; Superfund Remedy Report; Fifteenth Edition; EPA 542 R-17 01; July 2017; https://www.epa.gov/remedytech/superfund--remedy--report
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; EPA430-R-16-004; https://www.epa.gov/climate-indicators
5	U.S. EPA; Green Infrastructure; https://www.epa.gov/green-infrastructure/green-infrastructure-climate-resiliency
6	U.S. EPA; Water Reuse Action Plan; https://www.epa.gov/waterreuse/water-reuse-action-plan
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 requirements 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.
More examples of tools to help assure adaptive
capacity of a site remedy are described online at
Superfund Climate Resilience: Adaptive Capacity.
Dam impoundment and upgradient water treatment
plant at the Summitville Mine site in the San Juan
Mountains of Colorado.
8

-------