EPA-542-F-15-010
April 2015
United States
Environmental Protection
Agency
orum issue roper
Ground Water Technical Considerations
during the Five-Year Review Process
Table of Contents
1. INTRODUCTION 1
2. FYR TECHNICAL REVIEW TEAM 2
3. TECHNICAL CONSIDERATIONS
DURING THE SCOPING MEETING 2
4. VALIDATION OF THE
HYDROGEOLOGIC CSM 2
5. GROUNDWATER DOCUMENT REVIEW 3
6. GROUNDWATER DATA REVIEW 4
7. GROUNDWATER CONSIDERATIONS
FOR THE SITE INSPECTION 4
8. GROUNDWATER TECHNICAL
ASSESSMENT 5
9. GROUNDWATER REMEDY
PERFORMANCE 6
11. CONCLUSIONS 7
10. EXAMPLE GROUNDWATER ISSUES
AND RECOMMENDATIONS 7
12. CITED REFERENCES 7
13. ACKNOWLEDGMENTS 9
14. NOTICE AND DISCLAIMER 10
15. TABLES 11
Table 1. Common Technical Questions
at Groundwater Sites 11
Table 2. Remedial Performance
Technical Elements to Evaluate 14
16. FIGURES
21
Figure 1. Hydrogeologic CSM Example
Block Diagram 21
Figure 2. Hydrogeologic CSM Example
Cross Section 22
Figure 3. Groundwater/Surface Water
CSM Example 23
17. KEY TECHNICAL RESOURCES FOR
FYRS AT GROUNDWATER SITES 24
1. INTRODUCTION
This issue paper has been developed to highlight technical consid-
erations as well as technical resources available to Remedial Project
Managers (RPMs) in conducting Five-Year Reviews (FYRs) at
CERCLA1 sites with contaminated groundwater. While it has been
developed with the needs of the U.S. Environmental Protection
Agency's (EPA) RPMs in mind, it may also be helpful to other
federal and state agencies that have the lead for conducting FYRs
and may assist EPA staff in reviewing those FYRs. In addition,
Table 1 provides FYR teams with examples of technical consider-
ations that can be used as a resource for practicing hydrogeologists
when reviewing groundwater remedy implementation.
Groundwater is the pathway of concern at many sites, either as a
potential water supply source or as the medium for transporting
contaminants that then discharge to sediments, surface water, or
air. Many of the more challenging CERCLA remedies involve the
management of contaminated groundwater, whether the remedial
action objectives (RAOs) include restoration or containment. Almost
90 percent of National Priorities List sites with remedy decisions have
a remedy that addresses contaminated groundwater (EPA? 2014).
This issue paper is not guidance. Instead, it outlines technical
considerations and resources within EPA regions and states
to help RPMs consider groundwater concerns in more detail
throughout the FYR process. The issue paper also highlights the
importance of involving a hydrogeologist2 early and consistently
throughout the FYR process for groundwater sites. It identifies
technical information that may benefit from review by and input
from hydrogeologists. It also suggests opportunities for identifying
groundwater remedy issues and developing recommendations to
address them. Finally, it provides a list of references and technical
resources for RPMs and technical staff.
1 Comprehensive Environmental Response, Compensation, and Liability Act,
also referred to as "Superfund"
2 A hydrogeologist as referred to in this report can be either a hydrologist,
environmental scientist, geologist or earth scientist/engineer that is trained
to understand the physical and chemical aspects of the groundwater remedy
(e.g., the conceptual site model (CSM), groundwater extraction and injection
system integrity, and long-term monitoring program)
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2. FYR TECHNICAL REVIEW TEAM
Conducting FYRs at complex sites may benefit from
EPA establishing a multi-disciplinary technical review
team (EPA, 2001). The members of the technical review
team provide technical expertise and assistance to RPMs.
Many groundwater site conditions are so complex and
unique that the GWF recommends that the technical
review team include a hydrogeologist. If EPA does not
have this expertise available in their regional office, it is
recommended that the RPM explore opportunities to
leverage other EPA and state technical resources. These
resources may include experts in other EPA regions,
EPA Technical Support Centers (e.g., the Groundwa-
ter Technical Support Center) and EPA Headquarters
support (e.g., Environmental Response Team and the
Technology Assessment Branch). In addition, some
states and other federal agencies (e.g., the U.S. Geologi-
cal Survey and the U.S. Army Corps of Engineers) have
technical experts available to provide valuable input.
At sites where EPA is the lead agency for the FYR,
the technical review team may be involved throughout
the FYR process. If EPA is not the lead agency, the
team's involvement in a FYR may be limited to review-
ing relevant site documents and a final or draft final
document developed by the lead agency. The remainder
of this document is written assuming the participation
of a hydrogeologist on the technical review team.
3. TECHNICAL CONSIDERATIONS DURING THE
SCOPING MEETING
For FYRs where EPA is the lead agency, a scoping
meeting with the technical review team is generally
conducted early in the FYR process. Below are some
recommendations of groundwater topics to be consid-
ered and discussed during this meeting:
Ensure the team understands the decision document
requirements (e.g., groundwater RAOs and associated
cleanup levels), expected timeframe(s) to achieve RAOs,
source control activities and RAOs, and the remedial
actions selected.
Identify available information related to current ground-
water conditions and remedy progress (e.g., sampling
data, updated conceptual site model (CSM), and ground-
water remedy completion strategy3).
Determine if existing groundwater data are sufficient to
conduct a meaningful analysis of remedy performance.
If not, identify additional monitoring data needed.
Identify the groundwater concerns expected to take
the most time to resolve (e.g., Is the plume behaving as
expected? Are there possible new exposure routes?).
Properly schedule the collection and analysis of any new
data needed for the FYR (e.g., installation of additional
wells and related sampling and analysis) to ensure proper
consideration in the review cycle.
Ensure that the team is aware of the anticipated time-
frame for the FYR process, particularly document review
periods.
At sites where EPA is not the lead, it is recommended
that the RPM consult with the technical review team
to ensure all applicable reports can be reviewed a few
months before the draft FYR report is due. This process
is already established in some EPA regions and has been
very effective for all parties involved.
4. VALIDATION OF THE HYDROGEOLOGIC CSM
Validation of the CSM by the technical review team is
a critical part of the technical evaluation of ground-
water remedies. The CSM requires revision with the
expansion of site knowledge and serves as a primary
project planning and management tool (EPA? 2011 a).
New site data and scientific insights into how contami-
nants migrate in groundwater ensure that the CSM will
always be a work in progress.
At sites with contaminated groundwater, the CSM
generally includes two major components: 1) the
pathway-receptor network diagram, which is mainly
used by risk assessors and concentrates on whether
receptors exist and whether pathways are complete;
and 2) the hydrogeologic CSM, which focuses on the
occurrence, fate and specific migration pathways of
contaminants in all site media, and aims to include all
the factors that control contaminant distribution and
3 For more information on groundwater remedy completion
strategies, refer to http://epa.gov/superfund/health/conmedia/
gwdocs/pdfs/EPA Groundwater Remedy Completion.pdf
2 Ground Water Forum Issue Paper
3 Water Technical Considerations during the Five-Year Review Process
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remedy effectiveness. The GWF recommends that both
CSM components be reviewed during the FYR process.
A hydrogeologic CSM provides a framework for evaluat-
ing the groundwater data and information. In some
instances, the technical review team may identify early
in the FYR process (e.g., during the scoping meeting)
that the site does not yet have a hydrogeologic CSM. In
such cases, it is suggested that the hydrogeologist work
with the RPM using available data to develop a prelim-
inary hydrogeologic CSM. As discussed in the previous
section, the hydrogeologist may also identify issues with
the completeness of an existing CSM. In this case, the
hydrogeologist may recommend the CSM be updated
with the collection and evaluation of additional data.
More information about the hydrogeologic CSM is
found in the highlight box.
The Hydrogeologic Conceptual Site Model: What is it and why is it important?
The hydrogeologic CSM focuses on the occurrence, fate and migration pathways of contaminants in all site
media. It is meant to include all the factors that control contaminant distribution and remedy effectiveness. The
hydrogeologic CSM should be described well enough to enable the technical review team to evaluate whether
the data collected to date, and other new information, are consistent with the contaminant behavior predicted
by the existing CSM. If not, elements of the CSM may need updating to reflect any new information. Typically,
figures are necessary to ensure that the team can visualize and understand the hydrogeologic CSM (See example
CSM figures at the end of this document.). Cross sections, particularly multiple or intersecting cross sections,
can be useful for visualizing complex sites in three dimensions. Understanding of complex contaminant sources,
in particular, can be improved through use of more sophisticated visualization tools (e.g., three-dimensional
geostatistical models), which can provide a variety of visual outputs that show source strength and distribution.
With adequate data, visualization tools also can be used to estimate contaminant mass. In addition to facilitating
the current review, an updated or newly developed CSM will benefit future remedy assessments.
Scientific understanding of how sources persist and contaminants migrate has advanced greatly since the
Superfund program began. Therefore, the GWF recommends considering new science when reviewing or
updating the CSM. Site assumptions made years ago may have been based on more limited information or
concepts that are more fully or differently understood today. For example, although dense non-aqueous phase
liquids (DNAPLs) were recognized as subsurface contaminant sources early in the Superfund program, our
understanding of DNAPL sources and the resulting plume architecture has evolved and is still developing
today. Our current understanding of contaminant behavior has resulted in significant changes in strategies
for characterizing source and plume extent, estimating cleanup timeframes for remedial actions, and assessing
whether the remedy is adequate to meet RAOs or whether the RAOs are technically practicable. Understand-
ing of the local hydrogeology also may change over time. For example, an aquitard that was thought to be
regionally thick and continuous may subsequently be found to be discontinuous or thin in places, calling into
question previous assumptions about the potential for contaminant transport to deeper aquifers.
For more information, consult, 'Environmental Cleanup Best Management Practices: Effective Use of the Project Life
Cycle Conceptual Site Model (EPA. 2011 a).
5. GROUNDWATER DOCUMENT REVIEW
The GWF recommends that the technical review team
review site documents that support the groundwater
technical evaluation. It may be helpful to provide these
documents electronically in a central location (e.g.,
Micros oft OneDrive) for the technical review team
to review.
The following documents may assist the technical review
team in the FYR process. More detail is provided for
information of particular interest to the hydrogeologist
team member.
1. Remedial investigation and feasibility study (RI/FS)
reports that describe the CSM (including site hydroge-
ology and the nature and extent of contamination) and
evaluate the selected remedial alternative.
Ground Water Technical Considerations during the Five-Year Review Process
Ground Water Forum Issue Paper 3
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2. Baseline human health (and ecological, if appropriate)
risk assessments conducted as part of the RI/FS.
3. Decision documents, including all the figures and tables,
which are not always available in the online versions,
especially older records of decision (RODs). The ROD
generally establishes RAOs and selects remedial actions
that either contain sources or portions of plumes,
reduce concentrations, restore contaminated ground-
water, prevent exposure, or require improvements to
drinking water. It is important for the technical review
team to understand the groundwater restoration and
associated cleanup timeframe, and containment remedy
elements in the ROD.
4. Remedial design and remedial action (RD/RA) work
plan, including the monitoring strategy and design
(i.e., the operations and maintenance (O&M) plan or
compliance monitoring plan).
5. Remedial design investigation reports.
6. Any document that presents an updated CSM.
7. Any document that presents a performance evaluation
of a remedy component (e.g., pump and treat capture
zone analysis or groundwater modeling report).
8. All previous FYRs for the site.
9. Current monitoring plans (including standard operat-
ing procedures), quality assurance project plan, or
other documents that set forth the required locations,
methodologies, and frequency of sampling for all media
being remediated.
10. Historical site data including water-quality and water-
level data along with well construction information,
ideally compiled in an electronic format (spreadsheet
or database) that can be manipulated; a complete set
of well logs; any changes that have occurred to the
monitoring well network since the previous FYR
(e.g., new, modified or decommissioned wells); and
O&M reports, which may be separate from the annual
monitoring reports.
6. GROUNDWATER DATA REVIEW
The hydrogeologist reviews contaminant concentra-
tion data to identify trends, anomalies and data gaps. A
major element of the technical review at contaminated
groundwater sites is the comparison of contaminant
concentrations in each well to: 1) the plume behavior
anticipated based on the hydrogeologic CSM; and 2)
remedy expectations established in the site decision
documents. This comparison typically includes perform-
ing or reviewing statistical trend analyses of data
for individual wells and evaluation of overall plume
behavior, either through plume map comparisons over
time or through statistical analyses that describe changes
in plume characteristics over time (e.g., MAROS package
analyses4). In particular, the team needs to confirm that
the plume is not expanding or behaving in an unantici-
pated way, and that timely progress is being made toward
meeting RAOs and associated cleanup levels.
Ideally, the data should be made available to the technical
review team to review in enough time for this evalua-
tion. The hydrogeologist needs time to evaluate the
validity of the groundwater monitoring data and the
associated trends (including the appropriateness of
the statistical approach) in the monitoring reports. If
monitoring reports do not include a robust data analysis,
the hydrogeologist may need time to develop statistical
trends to include in the FYR report.
7. GROUNDWATER CONSIDERATIONS FOR THE
SITE INSPECTION
The GWF recommends that members of the technical
review team visit the site to evaluate current conditions,
including those related to the groundwater remedy.
The inspection allows the team to identify changes in
site conditions (e.g., new construction and exposure
pathways), confirm reported site conditions, and
evaluate the condition of existing remediation facilities
and monitoring networks. If any team member cannot
accompany the RPM on the site inspection or visit the
site separately, the RPM may consider documenting
these site conditions photographically.
If the RPM uses a site inspection checklist, the GWF
recommends that the hydrogeologist review the checklist
to ensure it includes an adequate evaluation of the
condition and functionality of the groundwater remedi-
ation facilities and monitoring networks.
Examples of issues related to groundwater remedies
that may be encountered during the FYR site inspec-
tion include excessive vegetation that blocks access to
4 MAROS 3.0 is available at: http://old.gsi-net.com/en/softwafe/
free-software /maros-30. html
4 Ground Water Forum Issue Paper
3 Water Technical Considerations during the Five-Year Review Process
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monitoring wells and the loss of monitoring wells as a
result of site redevelopment or maintenance.
In addition, if previous evaluation of analytical data
identified possible problems with sampling procedures
or data quality, the GWF recommends, if possible, that
the hydrogeologist and RPM schedule the site visit to
coincide with a sampling event.
8. GROUNDWATER TECHNICAL ASSESSMENT
Beyond the document review, data review, and site
inspection, the technical review team may assist the RPM
in answering the three technical assessment questions in
the 2001 Comprehensive Five-Year Review Guidance:
Question A Is the remedy functioning as intended by
the decision documents?
Question B Are the exposure assumptions, toxicity
data, cleanup levels, and RAOs used at the time of the
remedy selection still valid?
Question C Has any other information come to light
that could call into question the protectiveness of the
remedy?
This GWF issue paper outlines recommended concepts,
particularly those related to groundwater, that may be
evaluated by the hydrogeologist to assist the RPM in
developing answers to these questions. It also identifies
possible issues that may arise for groundwater remedies,
and provides some examples of recommendations that
may be considered.
/. CSM validation: Site characterization efforts conducted
to date should generally be reflected in the current CSM.
In some cases, data may be insufficient to develop or
maintain a robust hydrogeologic CSM. If the hydro-
geologist cannot validate the CSM, this may lead to
questions regarding the performance of the remedy. If
time allows, it may be appropriate to conduct additional
sampling activities to support the FYR process. If not,
it may be appropriate to identify the data needs and
recommend additional sampling activities.
2. Long-term monitoringprogram and groundwater remedy comple-
tion strategy: The hydrogeologist evaluates the data to
ensure that the current long-term monitoring program
effectively characterizes the plume and allows the
evaluation of progress toward RAOs and associated
cleanup levels. This evaluation includes a review of
monitoring well placement and construction, as well
as the quality of data obtained from monitoring wells,
to ensure that both hydrogeologic and water quality
data are representative and reliable. Because sampling
protocols and equipment have improved over time, as
has our understanding of what a given groundwater
sample represents, it is suggested that sampling proto-
cols be reviewed to confirm that they are sufficient
for obtaining representative samples. Data evaluation
may also include a review of the site-specific ground-
water remedy completion strategy documentation
to ensure that monitoring data are being evaluated
against appropriate performance metrics and remedy
evaluation decisions. Following review of the monitor-
ing plan, the hydrogeologist may suggest including a
recommendation to conduct spatial and/or temporal
long-term monitoring optimization (LTMO) to verify
and continually improve the effectiveness and efficiency
of groundwater remedies. For example, evaluation
of the frequency and spatial density of sampling can
help determine if monitoring can be scaled back.
Conversely, analysis of the monitoring program may
identify apparent monitoring gaps and indicate the
need for a geospatial analysis of the monitoring well
network. Some LTMO software packages include
geospatial analysis modules for this purpose (EPA,
2005): however, such analyses do not take groundwater
gradients into account and generally cannot identify
when plumes are unbounded unless contaminant trends
are increasing in a network boundary well. Based on a
review of the groundwater remedy completion strategy
documentation, the hydrogeologist may also suggest
including a recommendation to either modify the
strategy components (i.e., performance metrics and/or
remedy evaluations). In the event that the groundwater
remedy completion strategy is not clearly documented,
the hydrogeologist may also suggest including a recom-
mendation to develop a more robust groundwater
remedy completion strategy document.
3. Monitoring well integrity. The hydrogeologist evaluates well
conditions to determine if redevelopment or replace-
ment of any monitoring wells is necessary. Over time,
degradation of a monitoring well's performance can
occur through sedimentation, corrosion, or biofouling.
The GWF recommends that a desktop review of the
sampling records be conducted to identify possible
degradation of well integrity. Sampling field notes may
Ground Water Technical Considerations during the Five-Year Review Process
Ground Water Forum Issue Paper 5
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reveal red flags such as changes in measured well depth,
changes in drawdown behavior during well purging,
or changes in indicator parameters such as turbidity.
During the site inspection, the technical review team
visually inspects all wells for any damage, inside and
outside. If damage is found that affects performance
of the well, or could cause the well itself to become a
potential contaminant migration pathway, the hydroge-
ologist may recommend the well be repaired, replaced
or decommissioned. For example, a well left uncapped
can be vulnerable to surface contamination or vandal-
ism. If exterior damage that may alter wellhead eleva-
tions is found, the hydrogeologist may identify this as
an issue and provide a recommendation to resurvey any
affected wells to ensure that groundwater flow gradients
are not mis characterized.
4. Groundwater extractioni'injection/ re-infiltration system integrity.
The GWF recommends that the technical review team
assess the integrity of any site pumping wells, re-injec-
tion wells, or re-infiltration galleries. The hydrogeologist
identifies any issues with the system's performance and
recommends corrective activities (e.g., redevelopment
or replacement). Likewise, if some portion of the
system is not functioning optimally, the hydrogeologist
evaluates the effects on the overall system to ensure that
any pump and treat remedy is operating effectively. If
the hydrogeologist determines that the system is not
functioning optimally or if plume capture could be
compromised, the hydrogeologist may identify a data
need and recommend a formal capture zone analysis
(EPA. 2008a).
5. Assessment of new information: As part of the FYR process,
the technical review team reviews site documentation,
current site conditions, and contaminant-specific
information to check for changes regarding exposure
assumptions, contaminant toxicity, cleanup levels, new
contaminants, and standards. While a risk assessor will
typically provide guidance on changes in toxicity and
cleanup levels, a hydrogeologist may provide input on
changes in exposure assumptions or new contami-
nants identified in groundwater sampling activities. In
addition, there may be new information that changes
our understanding of site hydrogeology or new site
features that might affect groundwater flow or exposure
to site contaminants. These features could include new
ponds, new public supply or other large capacity pumping
wells, or newly paved or unpaved surfaces. Hydrogeologic
impacts of these features might include changes in water
recharge rates, groundwater flow directions or velocity,
groundwater contaminant vapor migration into ambient
or indoor air (EPA, 2012a). or groundwater discharge to
surface water. Changes in land use may also indicate the
potential for new exposure pathways. If new information
suggests a change to assumptions made at the time of
remedy selection, this may be identified as an issue.
6. Institutional controls: The adequacy of and compliance
with implemented institutional controls (ICs) limiting
groundwater use for the site are generally evaluated
during the FYR process. The GWF reccommends
that the technical review team identify and evaluate
any changes in land use that may create the potential
for exposure to groundwater. Changes may include
the installation of new wells or new construction over
shallow plumes. In addition, if a review of monitor-
ing data indicates that a plume is expanding, the team
may recommend that the existing groundwater ICs be
modified and operational updates be implemented to
address plume expansion.
Table 1 provides this list of topics and related questions
that hydrogeologists commonly evaluate at groundwater
sites.
9. GROUNDWATER REMEDY PERFORMANCE
The FYR evaluates remedy performance to determine
if the remedy is functioning as intended. The FYR also
presents a good opportunity to evaluate the ground-
water remedy components to ensure they function well
together and are effective and cost efficient. In addition,
the FYR provides an opportunity to review existing data,
performance metrics and remedy evaluation decisions
to evaluate whether the estimated remedial timeframe is
achievable with the implemented remedy (EPA? 2012b).
If the technical review team identifies issues with system
performance, it may recommend characterization activi-
ties such as determining plume stability, containment or
plume hydraulic capture. In some cases, an evaluation
of remedy performance may result in recommendations
to consider a remedy change. For example, the hydroge-
ologist may recommend evaluating a transition to more
passive treatment technologies (e.g., monitored natural
attenuation) as part of the groundwater treatment
train. Conversely, poor remedy performance may be
6 Ground Water Forum Issue Paper
3 Water Technical Considerations during the Five-Year Review Process
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attributed to remaining groundwater contaminant
sources that require additional characterization. Based
on the remedy-specific characteristics, the technical
review team may suggest that the RPM either consider
enhancements to the existing remedy (e.g., more aggressive
source treatment or in situ plume treatments) or recommend
evaluating an alternative remedial strategy (e.g., a technical
impracticability or "TI" waiver (EPA. 1993)5). Table 2 lists
some specific issues to consider for common remedial
technologies for contaminant sources and associated
groundwater plumes.
10. EXAMPLE GROUNDWATER ISSUES AND
RECOMMENDATIONS
As discussed in the previous sections, when groundwater
issues are identified throughout the FYR process, the
technical review team works with the RPM to document
these issues and develop clear and concise recommen-
dations to address them.
Some common groundwater remedy issues that may be
identified include, but are not limited to the following:
Underestimated source mass, both in the saturated and
the unsaturated zones.
Underestimated source extent, including unidentified
source areas.
Inadequately characterized groundwater plumes in
three dimensions, including insufficient information
to identify and monitor the most contaminated plume
intervals or to recognize the potential for migration of
contaminants through presumed aquitards.
Inadequately documented or unclear groundwater rem-
edy completion strategy.
Inadequate understanding of the effect of matrix storage
on remedial time frames due to back diffusion.
Inadequate understanding of connections with other
exposure media, including surface water, sediment, and
soil vapor (and potentially complete exposure pathways
associated with vapor intrusion).
5 Both EPA (EPA. 20lib) and the National Research Council
(NRC. 2012) have recommended processes for evaluating
alternative strategies in the event that a groundwater remedy is
not progressing as anticipated and is unlikely to meet remedial
goals.
Contaminants not previously identified as a concern.
For example 1,4-dioxane may not have been previously
identified as a contaminant of concern at the ROD stage
because the detection limit may have changed.
In general, recommendations are developed to address
the issues raised in the review. These recommendations
will be specific to site conditions and reflect specific
activities necessary to effectively address the issue.
11. CONCLUSIONS
Groundwater sites and remedies have specific technical
issues and complexities that are better understood by
hydrogeologists and other groundwater experts. EPA,
other federal agencies, and states have a significant
amount of technical expertise available to assist the
RPM in conducting FYRs that include groundwater
components. Leveraging these resources, as part of
the FYR technical review team, will assist the RPM in
reviewing complex groundwater site conditions and
remedies. When a technical review team is developed
to review groundwater elements of a remedy, the GWF
recommends that they are involved early in the FYR process
to ensure they have adequate time and resources necessary
to conduct data review, document review, and participate
in the site inspection. This time frame will depend on the
complexity of the site and remedies implemented. Profes-
sional judgment is required to properly schedule a FYR.
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EPA, 2004b. What Is Remediation Process Optimisation and
How Can It Help Me Identify Opportunities for Enhanced and
More Efficient Site Remediation? Sponsored by: Interstate
Technology and Regulatory Council. September.
Archived presentation available at: http://www.clu-in.
org/conf/itrc/rpo 092804/
EPA, 2005. Roadmap to Eong-TermMonitoring Optimisation.
(EPA 542-R-05-003). May. Available at: http://www.epa.
gov/tio/download/char/542-r-05-003.pdf
EPA, 2007a. Monitored Natural Attenuation oj
Contaminants in Ground Water, Volume 1: Technical Basis
for Assessment (EPA 600-R-07-139). October. Available
at: http://nepis.epa.gov/Adobe/PDF/60000N4K.pdf
EPA, 2007b. Monitored Natural Attenuation of Inorganic
Contaminants in Ground Water, Volume 2: Assessment for
Non-Radionuclides, Including Arsenic, Cadmium, Chromium,
Copper, Eead, Nickel, Nitrate, Perchlorate, and Selenium (EPA
600-R-07-140). October. Available at: http://nepis.epa.
gov/Adobe/PDF/60000N76.pdf
EPA, 2007c. Optimisation Strategies for Eong-Term Ground
Water Remedies (with Particular Emphasis on Pump and Treat
Systems). (EPA 542-R-07-007). May. Available at: http://
www.cluin.org/download/remed/hyopt/542r07007.pdf
EPA, 2008a. A Systematic Approach for Evaluation of Capture
Zones at Pump and Treat Systems (EPA/600/R-08/003).
January. Available at: http://cfpub.epa.gov/si/si_public_
record_report.cfm?dirEntryId= 187788
EPA, 2008b. Interim Record of Decision, Moses Eake Wellfield
Superfund Site, Moses Eake, Washington. September. Page
14. Available at: http://www.epa.gov/regionlO/pdf/
sites/moses_lake_wellfield/mlwc_interim_ROD.pdf
EPA, 2009a. GroundWaterlssue: Assessment andDelineation
of DNAPE Source Zones at Hazardous Waste Sites. (600-R-
09-119). September. Available at: http://www.epa.gov/
ada/pubs/issue.html
EPA, 2009b. Third Five-Year Review Report for Commence-
ment Bay Nearshore/Tideflats Superfund Site. Tacoma,
Washington. December. Available at: http: / /www.epa.gov/
regionlO/pdf/sites/cb-nt/cbnt_3rd_5yr_122309.pdf
Ground Water Forum Issue Paper
rf Water Technical Considerations during the Five-Year Review Process
-------
EPA, 201 la. 'Environmental Cleanup 'Rest Management
Practices: Effective Use of the Project Life Cycle Conceptual Site
Model. (EPA 542-F-l 1-011). July. Available at: http://
epa.gov/tio/download/remed/csm-life-cycle-fact-
sheet-final.pdf
EPA, 20 lib. Groundwater Road Map: Recommended Process
for Restoring Contaminated Groundwater at Superfund Sites.
(OSWER 9283.1-34). July. Available at: http://www.
epa.gov/superfund/health/conmedia/gwdocs/pdfs/
gwroadmapfinal.pdf
EPA, 201 Ic. An Approach to Evaluating the Progress of
Natural Attenuation in Groundwater. (EPA 600/R-l 1/204).
December. Available at: http://nepis.epa.gov/Adobe/
PDF/PlOODPOE.pdf
EPA, 2012a. Assessing Protectiveness at Sites for Vapor
Intrusion: Supplement to the "Comprehensive Five-Year Review
Guidance." (OSWER Directive 9200.2-84). November.
Available at: http://www.epa.gov/superfund/cleanup/
pos tcon structi on/pdfs/VI_F YR_Gui dance-Fi-
nal-ll-14-12.pdf
EPA, 2012b. National Strategy to Expand Superfund Optimi-
^ation Practices from Site Assessment to Site Completion.
(OSWER Directive 9200.3-75). September. Available
at: http://www.epa.gov/oerrpage/superfund/cleanup/
postconstruction/2012strategy.pdf
EPA, 2012c. A Citizen's Guide to Soil Vapor Extraction
and Air Sparging. (EPA 5542-F-12-018). September.
Available at: http://www.clu-in.org/download/citi2ens/
citsve.pdf
EPA, 2012d. A Citizen's Guide to Bioremediation. (EPA
542-F-12-003). September. Available at: http://www.
clu-in.org/download/citizens/bioremediation.pdf
EPA, 2012e. A Citizen's Guide to Capping. (EPA 542-F-12-
004). September. Available at: http://www.clu-in.org/
download /citizens /a_citJ2ens_guide_to_capping.pdf
EPA, 2012E A Citizen's Guide to Permeable Reactive 'Barriers.
(EPA 542-F-12-015). September. Available at: http://
www.clu-in.org/download /Citizens /a_citizens_guide_
to_permeable_reactive_barriers.pdf
EPA, 2014. Groundwater Remedy Completion Strategy
(OSWER Directive 9200.2-144). May. Available at:
http://www.epa.gov/superfund/health/conmedia/gwdocs/
pdfs/EPA_Groun dwater_Remedy_Completion.pdf
ESTCP (Environmental Security Testing and Certifica-
tion Program), 2007. Frequently Asked Questions Regarding
Management of Chlorinated Solvents in Soils and Groundwater.
July. Available at: http://serdp-estcp.org/content/
download/5045/72039/file/ER-0530-FAQ.pdf
FRTR (Federal Remediation Technologies Roundta-
ble), 2002. Evaluation of Permeable Reactive Carrier Perfor-
mance. Available at: http://www.clu-in.org/download/
rtdf72-prbperformance_web.pdf
ITRC (Interstate Technology & Regulatory Council), 2004.
Remediation Process Optimisation: Identifying Opportunities for
Enhanced and More Efficient Site Remediation. RPO-1. ITRC,
Washington, DC September. Available at: http://www.
itrcweb.org/Guidance/GetDocumentPdocumentID=78
NRC (National Research Council), 20\2. Alternatives for
Managing the Nation's Complex Contaminated Groundwater
Sites. National Academies Press. Available at: http://
www.nap.edu/catalog.php?record_id= 14668
13. ACKNOWLEDGMENTS
A document of this scope involved significant participa-
tion from a number of people, such that any omission
in these acknowledgments is purely unintentional. The
Ground Water Forum thanks all of the participants
involved in the development of this document. We
acknowledge the active participation and valuable input
from our workgroup co-leads, Marcia Knadle of EPA
(Region 10, retired) and Kay Wischkaemper (Region 4,
retired), and workgroup members Jean Choi (Region 1),
Mike Scorca and Kevin Willis (Region 2), Vince Malott
(Region 6), Lisa Gotto and Dan Nicoski (Region 7),
Rene Fuentes and Jonathan Williams (Region 10), Mike
Bailey (U.S. Army Corps of Engineers), and Barb Vetort
(Michigan Department of Environmental Quality).
Other contributors and reviewers included Matt Charsky
(retired), Anne Dailey, Linda Fiedler, Kate Garufi, Ed
Gilbert, Tracy Hopkins, Mike Hurd (retired), and Steve
Ridenour (EPA Office of Superfund Remediation and
Technology Innovation).
Ground Water Technical Considerations during the Five-Year Review Process
Ground Water Forum Issue Paper 9
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14. NOTICE AND DISCLAIMER
The Ground Water Forum, a component of the U.S.
EPA Superfund Technical Support Project, has authored
this issue paper. Information and opinions contained
in this document were developed by the Ground Water
Forum, are technical in nature, and represent profes-
sional opinions of the participants. This information
has not received formal EPA peer review and does not
necessarily reflect the views of EPA or other participat-
ing organizations, and no official endorsement should be
inferred. The information is not intended, nor can it be
relied upon, to create any rights enforceable by any party
in litigation with the United States or any other party.
Use or mention of trade names does not constitute an
endorsement or recommendation for use.
A PDF version of Ground Water Forum Issue Paper:
Groundwater Technical Considerations during the Five-Year
Review Process is available to view or download at http://
www.epa.gov/superfund and http://www.cluin.org.
10 Ground Water Forum Issue Paper
3 Water Technical Considerations during the Five-Year Review Process
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15. TABLES
Table 1. Common Technical Questions at Groundwater Sites
Review Needs
Questions
GSM validation
Review documentation of the site
geological and hydrological charac-
terization. This includes the RI/
FS reports, along with any supple-
mental information that was used
to develop the findings presented in
the ROD and any characterization
performed during RD/RA.
Considering the current state of the practice, have
the site characterization efforts conducted to date
been sufficient?
Is the CSM adequate and up to date?
Has the three-dimensional nature and extent of
contamination been fully delineated?
Has the potential for dense non-aqueous phase liquid
(DNAPL) source been adequately considered, includ-
ing the potential for DNAPL movement through
aquitards (Bradbury, et al. 2006)?
Might other contaminants be present that were
unknown then or are of greater concern today?
Were contaminant migration pathways to sediment
and surface water fully characterized?
Has the potential for vapor intrusion been evaluated?
Long-term monitor-
ing program
(adequacy of
monitoring well
network and data
quality and quantity)
Review the adequacy of the
monitoring well network, including
construction details of the existing
monitoring wells to develop a
technical evaluation of the monitor-
ing well design and construction.
This may require review of well
logs.
Review the sampling and analysis
plan, including standard operat-
ing procedures, and the quality
assurance project plan (QAPP). This
review may involve both a hydroge-
ologist and a quality assurance
expert. Field oversight of a sampling
event may be advisable.
Have the wells been properly placed, both horizontally
and vertically, to define the plume(s), to characterize
concentrations throughout the aquifer thickness and
to track the rate and extent of plume migration?
Are the screen intervals and lengths appropriate?
Are additional wells needed in response to changes
in plume configuration?
If there is a pump-and-treat remedy, are wells appro-
priately located to provide information for a capture
zone analysis?
Are monitoring wells accessible to EPA and its
contractors yet protected from likely avenues of
accidental damage or vandalism? (Wells with flush
mount completions are particularly vulnerable to
burial under gravel or pavement.)
Are appropriate chemical constituents being analyzed
at appropriate quantitation limits, including parent/
daughter (biodegradation) products, indicators of
change in geochemical conditions, as well as the site's
chemicals of concern?
If new chemicals of potential concern have been
identified, have they been included in the analytical
program?
Are sampling protocols appropriate and up to date?
Are monitoring wells being sampled at an appropri-
ate frequency to establish and maintain statistically
robust contaminant trends at appropriate locations
(e.g., source wells, plume centerline wells, boundary
wells, and sentinel wells)?
Ground Water Technical Considerations during the Five-Year Review Process
Ground Water Forum Issue Paper 11
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Table 1. Common Technical Questions at Groundwater Sites (continued)
Topic
Monitoring well
integrity
Review Needs
Assess the integrity of the site
monitoring wells. Parts of this
evaluation should be performed
in the office by reviewing the
sampling records to determine if
well integrity has been degrading,
and conditions should be confirmed
during the field visit.
Assess the integrity of any site
pumping wells, re-injection wells, or
re-infiltration galleries.
Questions
Are the monitoring wells functioning as designed and
constructed?
Is there a plan for periodic assessment and mainte-
nance?
Is total depth measured periodically to check for
sedimentation when water levels are measured?
Are there damaged, out-of-date, or poorly constructed
wells (e.g., those with inappropriately long screens)
that should be properly decommissioned?
Groundwater
extraction and
injection system
Are all the wells functioning? If not, what are the
ramifications for overall plume capture?
Is biofouling or premature pump failure an issue?
Are water levels unexpectedly low in pumping wells
or high in re-injection wells?
Are groundwater levels around infiltration galleries
consistent with historical operating conditions?
Revised and new
information
Check for changed or new informa-
tion regarding remedy assumptions.
Check whether site conditions have
changed in any way that could alter
groundwater flow conditions.
Have there been changes in contaminant toxicity,
cleanup levels, or groundwater standards?
Are there newly identified contaminants of potential
concern at the site?
Has enough analytical information been collected to
evaluate these questions?
Is there new information to indicate that RAOs may
not be achievable with the current remedy?
Are there new scientific insights that call a critical
element of the CSM into question?
At or near the site, are there new features (ponds,
public supply wells, newly paved or unpaved surfaces,
etc.) which may have affected groundwater recharge
or discharge or otherwise altered the subsurface
hydrogeology (e.g., groundwater flow directions or
velocity)?
Have there been land use changes that may lead to
exposures in a new population?
Institutional controls
(ICs)
Review the adequacy of and compli-
ance with implemented groundwater
ICs for the site.
Has land use or zoning changed?
Have any new water wells been installed in or near
the plume area?
Has there been new construction above shallow
plumes of volatile organic compounds (VOCs)?
Have such changes compromised the effectiveness
of groundwater remedies and/or presented new
exposures (e.g., vapor intrusion) that did not exist at
the time of remedy selection?
12 Ground Water Forum Issue Paper
3 Water Technical Considerations during the Five-Year Review Process
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Table 1. Common Technical Questions at Groundwater Sites (continued)
Topic
Environmental
indicators
Review Needs
Check to ensure consistency with
current understanding of site
conditions, including exposure
scenarios as confirmed during the
field visit.
Questions
Are the indicators for "human exposure under
control" and "migration of contaminated ground-
water under control" still valid?
Remedy optimization
Evaluate whether contaminant
concentration data may indicate a
need for remediation system evalua-
tion (EPA, 2000) or LTMO (EPA.
2005).
Is the groundwater remedy effective (and cost effec-
tive)
For a pump-and-treat remedy, has a capture zone
analysis been conducted recently?
Do the data suggest that there may be a contaminant
source that has not been controlled?
If contaminant levels have "tailed" and the plume is
stable, could monitored natural attenuation (MNA)
play a larger role in the groundwater remedy?
What are the life-cycle energy costs?
Could sampling frequencies be reduced without a
significant loss in ability to track contaminant trends?
Are there any redundant monitoring wells?
Ground Water Technical Considerations during the Five-Year Review Process
Ground Water Forum Issue Paper 13
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Table 2. Remedial Performance Technical Elements to Evaluate
Groundwater Remediation Common Groundwater Elements t
Description/Objectives c"~l1 "-*~
Internet Resources
Extraction Systems
Remove contaminated fluids, treat, and discharge (soil gas or water) to contain contamination and/or to restore
groundwater to beneficial use.
Groundwater Pump and
Treat fP&Tl
Actively extract contaminated
groundwater and treat
Have extraction systems captured the
entire plume length, width and depth (or
the entire target zone if the goal is partial
capture)?
Has the source area been remediated or
controlled successfully?
Did the site have light or dense non-aque-
ous phase liquids (LNAPL or DNAPL)
besides the dissolved plume, and were
these remediated?
Is the system meant to deal with a
dissolved plume or also with a NAPL
source?
Is any reintroduced treated water having
the anticipated effect on site hydraulics or
on the plume?
Does the treatment system remove all
the contaminants in the groundwater,
including newly identified contaminants
of concern?
A Systematic Approach for Evaluation of
Capture Zones at Pump and Treat Systems.
(EPA. 2008a).
Soil Vapor Extraction (SVE)
Actively remove contam-
inated soil vapor and
discharge, or treat and
discharge.
Was the SVE checked for meeting goals
of remedial action objectives after it was
shut down?
Has there been a rebound of ground-wa-
ter concentrations since the SVE was
turned off?
SVE only addresses unsaturated zone
(vadose) contamination. If implemented
to protect groundwater, might additional
sources exist in the saturated zone (below
the water table)?
Soil Vapor Extraction focus area:
http://www.clu-in.org/techfocus/
default.focus/sec/Soil Vapor
Extraction /cat /Overview/
In-Situ Treatment
Contaminants are actively or passively degraded or immobilized in the aquifer.
Air Sparging
Introduce air to vadose zone
and groundwater to enhance
removal from soils and
groundwater. Coupled with
soil vapor extraction.
Same as for SVE
A Citizen's Guide to Soil Vapor Extraction and
Air Sparging. (EPA. 2012c).
14 Ground Water Forum Issue Paper
3 Water Technical Considerations during the Five-Year Review Process
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Table 2. Remedial Performance Technical Elements to Evaluate (continued)
Groundwater Remediation Common Groundwater Elements t
Description/Objectives Evaluate
Bioremediation
Chemicals of concern are
remediated by bacteria. The
environment for increased
biologic activity can be
enhanced by injecting carbon
sources (oils, sugars) and/or
bacteria.
Is contaminant breakdown complete or
stuck at toxic intermediate forms?
Is breakdown fast enough?
Can injected amendments reach the entire
contaminated target zone?
Can necessary conditions be maintained
naturally?
Internet Resources
A Citizen s Guide to Bioremediation. (EPA.
2012d).
Phvtoremediation
Chemicals of concern are
taken up by the root zones of
plants (e.g., poplars and hyper-ac-
cumulating ferns) and destroyed
through metabolization.
Are the plants healthy?
Do the roots extend deep enough to
intercept a significant portion of the
plume mass?
Phytotechnologies focus area: http:
www.clu-in.org/techfocus /defaull
focus/sec/Phytotechnologies/cat/
Overview/
Monitored Natural Attenua-
tion
Monitor and confirm that
natural processes are remedi-
ating plumes in an acceptable
timeframe that would be
comparable to active remedi-
ation.
Evaluate whether natural attenuation is
progressing as expected, if not annually,
at least for each FYR. Use concentra-
tion trend analyses and possibly plume
moment analysis. If progress is inade-
quate, a more active remedy may be
required to meet cleanup objectives.
May also need to evaluate whether
additional untreated or uncontained
sources exist.
In some cases MNA cannot be sustained
over time; in others, site conditions may
not have been as favorable as was believed
when MNA was chosen.
There may be breakdown products which
are as much of a problem as the original
contaminant.
Geochemical conditions may vary season-
ally in shallow aquifers; The recommen-
dation is that monitoring plans account
for this temporal effect on contaminant
solubility's and associated transport.
Technical Protocol for Evaluating Natural
Attenuation of Chlorinated Solvents in
Ground Water. (EPA. 1998a).
Monitored Natural Attenuation of Inorganic
Contaminants in Ground Water, Volume
1: Technical Basis for Assessment. (EPA.
2Q07a).
Monitored Natural Attenuation of Inorganic
Contaminants in Ground Water, Volume
2: Assessment for Non-Radionuclides
Including Arsenic, Cadmium, Chromium,
Copper,Lead, Nickel, Nitrate, Perchlorate,
and Selenium. (EPA. 2007b).
An Approach for Evaluating the Progress
of Natural Attenuation in Groundwater.
(EPA. 2011c).
Ground Water Technical Considerations during the Five-Year Review Process
Ground Water Forum Issue Paper 15
-------
Table 2. Remedial Performance Technical Elements to Evaluate (continued)
Groundwater Remediation Common Groundwater Elements t
Description/Objectives c.,~i..~*~
Source Zone Remediation
Sources are identified, delineated, and removed or destroyed. "How clean is clean?" is a major question. RAOs
may be based on percentage of source mass destroyed or removed, but that is very difficult to determine.
Reductions in remaining groundwater concentrations, and/or reductions in mass flux to the groundwater plume
may be easier objectives to demonstrate. A treatment train approach may be most effective.
LNAPL Sources
NAPL sources are only
slightly soluble in water and
are persistent sources to
groundwater contamination
that are difficult to remove.
LNAPLs are easier to find
because they float on the
water table.
Were LNAPLs found or suspected at site?
Were LNAPLs removed or just contained
at site?
Have concentrations rebounded at site
due to LNAPLs?
Do multiple LNAPLs have different
solubilities and thus different transport
potentials?
Ground Water Issue: Light Non-Aqueous
Phase Uquids. fEPA. 1995V
DNAPL Sources
DNAPLs are difficult to
locate because they are
heavier than water and sink
through aquifers, potentially
until they reach a much less
permeable layer. In addition,
they may flow in relatively
narrow flowpaths, which are
easily missed, rather than
create a broader pool. They
may also pool or flow down
dip slope regardless of the
groundwater flow direction.
Were DNAPLs found or suspected at
site (groundwater concentrations > 1%
to 10% of DNAPL solubility)?
Were DNAPLs monitored at the site?
Were wells correctly screened to detect
DNAPLs?
Were DNAPLs removed or just contained
at site?
Have concentrations rebounded at site
due to DNAPLs?
DNAPL Focus Area: wwwcluin.org/
dnapl
Ground Water Issue: Assessment and
Delineation of DNAPL Source Zones at
Hazardous Waste Sites. (EPA. 2009aY
Frequently Asked Questions Regarding
Management of Chlorinated Solvents in Soils
Groundwater (ESTCP. 2007V
Excavation
Sources are dug up and
treated ex situ or disposed
elsewhere.
Could the entire source be excavated i.e.,
Was there contamination deeper than
excavation could reach, or was horizontal
excavation constrained by infrastructure?
If the water table varies seasonally, was
excavation performed when the water
table was low?
Were excavations backfilled with hydro-
geologically comparable soil to minimize
changes in site hydrology?
Was monitoring sufficient to evaluate
short-term and long-term effects on
downgradient groundwater?
DNAPL Focus Area: Source Area
Excavation: http: //www:clu-in.org/
contaminantfocus/default.focus/sec/
Dense Nonaqueous Phase Liquids
(DNAPLs)/cat/Treatment Technolo-
gies/p/10
16 Ground Water Forum Issue Paper
3 Water Technical Considerations during the Five-Year Review Process
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Table 2. Remedial Performance Technical Elements to Evaluate (continued)
Groundwater Remediation Common Groundwater Elements to
Description/Objectives Evaluate
Thermal Remediation
Internet Resources
Thermal energy (via steam or
electricity) is applied to soil
to remove and/or destroy
contaminants, either in situ or
ex situ (applied to excavated
material at the surface).
Contaminants are recovered
from the vapor phase (or
vapor and liquid phases,
in the case of steam) and
treated.
Is groundwater flow adequately controlled
to maintain target temperatures through-
out the treatment area?
Can the system be modified to increase
removal efficiency?
If the energy is injected via steam, did the
energy reach the entire source volume?
After shutdown, have concentrations
rebounded?
Ground Water Issue: How Heat Can
Enhance In-situ Soil and Aquifer ^medi-
ation: Important Chemical Properties and
Guidance on Choosing the Appropriate
Technique. fEPA. 1997V
Ground Water Issue: Steam Injection for Soil
and Aquifer Remediation. (EPA. 1998b).
In Situ Thermal Treatment focus
area: http://www.clu-in.org/techfo-
cus/default, focus/sec/Thermal
Treatment%3A In Situ/cat/
Overview/
In Situ Chemical Treatment
Chemicals are injected
into a contaminated area
to remove or destroy the
environment-contaminat-
ing chemicals of concern,
usually by manipulating redox
conditions.
Can the chemical conditions required to
treat source materials be maintained long
enough for complete treatment?
Did injected food or bacteria reach the
entire source volume?
Has the chemical treatment been success-
ful? Has the contamination rebound-
ed (come back after being reduced/
removed)?
In Situ Chemical Reduction focus area:
http://www.clu-in.org/techfocus/
default.focus/sec/In Situ Chemical
Reduction/cat/Qverview/
Bioremediation
Chemicals of concern are
remediated by bacteria. This
process can be enhanced by
enhancing the environment
for increased biologic activity.
Has the bioreaction produced other
contaminants of concern? Is the remedial
system continuing to operate efficiently?
Did injected food or bacteria reach the
entire source volume?
Bioremediation focus area:
http://www.clu-in.org/techfocus/
default.focus/sec/Bioremediation/cat/
Overview/
Containment Barriers
Containment barriers isolate contaminant sources with engineered structures. The source mass remains in place
and the integrity of the remedy is limited by the life of the engineered structure. The potential for leakage in both
horizontal and vertical directions should be considered. Long-term monitoring to detect releases through contain-
ment failure must continue for as long as the source exists, even after the plume outside the containment unit is
cleaned up.
Surface Engineered Barriers
Surface engineered barriers
(caps) reduce infiltration and
limit direct exposure.
Are "chemicals of concern" for a site
being observed in downgradient monitor-
ing wells at stable or increasing concen-
trations?
Is the cap continuing to allow runoff, or
has differential settlement caused ponding
on the surface?
Has large vegetation become established?
Are animals compromising the cap by
digging or burrowing?
A Citizen s Guide to Capping (EPA.
2012e).
Ground Water Technical Considerations during the Five-Year Review Process
Ground Water Forum Issue Paper 17
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Table 2. Remedial Performance Technical Elements to Evaluate (continued)
Groundwater Remediation Common Groundwater Elements to
Description/Objectives Evaluate
Subsurface Engineered Barriers
Internet Resources
Subsurface engineered
barriers (impermeable walls)
isolate hazardous wastes from
adjacent groundwater and
surface water.
If the containment surrounds a source
area, are water levels within the contain-
ment area unaffected by external water
level changes?
Are "contaminants of concern" for a
site being observed in downgradient
monitoring wells at stable or increasing
concentrations?
Can contamination flow around or under
the barrier?
Evaluation of Subsurface Engineered
Carriers at Waste Sites (EPA. 1998c).
Permeable Reactive Barriers
Reactive barriers are designed
to treat the entire plume as it
flows through, so understand-
ing and managing groundwa-
ter flow is critical. Reaction
products may gradually
reduce the permeability of
the barrier and cause the
reactants to become depleted
or unavailable.
Performance monitoring is critically
important for PRBs. Are downgradient
water concentrations as clean as expected?
If not, the wall may not be thick enough
to completely treat the plume, especially
if the plume is more stratified and has a
higher range of concentrations than was
anticipated at design.
Can it be demonstrated from sampling
and water level data that contamination
is not flowing around or beneath the
barrier? Is the wall still permeable? If
not, groundwater may be diverted around
or under the wall, especially if it was not
properly oriented relative to (i.e., at right
angles to) the local groundwater flow
direction. PRB cementation or bio fouling
can occur surprisingly quickly.
^4 Citizen s Guide to Permeabk Reactive
Carriers (EPA. 2012f).
Evaluation of Permeable Reactive Barrier
Performance. (FRTR 2002V
18 Ground Water Forum Issue Paper
3 Water Technical Considerations during the Five-Year Review Process
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Table 2. Remedial Performance Technical Elements to Evaluate (continued)
Groundwater Remediation Common Groundwater Elements t
Description/Objectives c"~l1 "-*~
Internet Resources
Monitoring
Monitoring is an integral element of all groundwater remedies, whether to evaluate the effects of a particular
remedial action on nearby groundwater or to evaluate the response of site-wide groundwater plumes. It is also
integral to the management of groundwater institutional controls.
Long-Term Monitoring
The long-term monitoring
plan must provide adequate
information to demonstrate
effectiveness.
In general, are wells properly sampled
using an acceptable sampling procedure?
Are the QAPP and work plan up to date?
Are plumes bounded on all sides by
monitoring wells? If the plume may be
advancing, are there enough sentinel
wells to evaluate plume migration in a
timely fashion, including vertically if
appropriate?
Do sampling and water level measurement
frequency account for seasonal effects, if
present?
Are there enough wells within the plume
to evaluate progress toward RAOs? (e.g.,
If reduction in plume mass is an objective,
are there enough centerline wells to track
changes in contaminant mass or plume
moments statistically?)
Have there been changes in groundwater
levels or gradients? Increasing ground-
water levels can increase groundwater
contamination when contaminants that
had been in the vadose zone are now
below the water table. Also, different
types of strata, such as gravelly layers, may
become saturated and allow contaminant
plumes to migrate much more quickly.
Ground-Water Sampling Guidelines for
Superfund and RCRA Project Managers.
rEPA. 2002V
Final RCRA Comprehensive Ground-Water
Monitoring Evaluation (CME) Guidance
Document. (EPA. 1986V
Ground Water Sampling for Metals
Analysis. (EPA. 1989V
RCRA Ground Water Monitoring. Draft
Technical Guidance. (EPA. 1992V
Cleanups at Federal Facilities (EPA
webpage with several good links):
http://www.epa.gov/fedfac/
documents/qualityassurance.htm#ufp-
qapp
Performance Monitoring
The monitoring program
at a site must be appropri-
ately designed to assure that
a specific remedial action
functions as designed. Once a
remedial action is determined
to be functional, the
long-term monitoring system
replaces it.
Are the wells in the network sufficient
and properly placed, both to ensure that
groundwater flow is as expected (water
level measurements) and to ensure that
remedial actions were effective (contam-
inant reductions where desired) and that
they didn't spread contamination (no
unanticipated plume spread)?
Were the wells sampled frequently enough
to identify changes attributable to the
remedial action?
Performance Monitoring of MNA Remedies
for VQCs in Ground Water. (EPA.
2Q04a).
Methods for Monitoring P&T Performance
Parts 1 and 2. (EPA. 1994V
Ground Water Technical Considerations during the Five-Year Review Process
Ground Water Forum Issue Paper 19
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Table 2. Remedial Performance Technical Elements to Evaluate (continued)
Groundwater Remediation Common Groundwater Elements to
Description/Objectives " '
Internet Resources
Optimization
Remedy optimizations can yield significant operational cost savings and improve remedy effectiveness, either by
increasing mass removal rates (thus reducing the length active remediation is required) or by ensuring that the
right amount of sampling data is collected.
Remedial Systems Evaluation /
Remedial Process Optimization
A remediation system may
need to be evaluated for
cost-efficiency and integrity
after it operates for a while.
Have concentration trends stopped
declining, or have they rebounded?
Is the groundwater capture zone well
understood?
Is biofoulingin pumping wells impacting
extraction rates?
Optimisation Strategies for Long-Term
Ground Water Remedies. (EPA. 2007c).
Remediation Process Optimisation: Identi-
fying Opportunities for Enhanced and More
Efficient Site Remediation. RPO-1. (TTRC.
2004^
Superfund Reform Strategy Pump and Treat
Optimisation: Questions and Answers.
http: //www.clu-in.org/download/
remed/hyopt/questionanswer2.pdf
What Is Remediation Process Optimisation
and How Can It Help Me Identify Opportu-
nities for Enhanced and More Efficient Site
Remediation? (EPA. 2004b)
Long-Term Monitoring
Optimization
Long-term monitoring can
periodically be optimized
both temporally to reduce the
frequency of sampling and
spatially to ensure that the
spacing of wells is sufficient
to meet monitoring objectives
while eliminating any
redundant wells.
Is groundwater sampling still being
conducted at the same frequency (quarter-
ly or semiannually) in all wells?
Are there seasonal variations in contam-
inant concentrations or in water levels?
Wells which are no longer needed for
sampling may still be useful for water level
measurements.
Roadmap to Long-Term Monitoring Optimi-
sation. rEPA. 2005V
MAROS Overview: http://www.frtr.
gov/decisionsupport/DST Tools/
maros.htm (MAROS 2.2)
MAROS 3.0: http://old.gsi-net.com/en/
software/free-software/maros-30.html
20 Ground Water Forum Issue Paper
3 Water Technical Considerations during the Five-Year Review Process
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16. FIGURES
Figure 1: Hydrogeologic CSM Example Block Diagram
A
0.
Area of Former Solvent Tank
and Ongoing Source Controls
Target Monitoring Zones
1. Source area L _l
2. Contaminated zones of highest
concentrations and mobility
3. Plume fringes exhibiting low
contaminant concentrations
4. Plume boundaries
5. Recalcitrant zone determined
from historical trends
6. Upgradient locations
Legend
Gravel,gravel-sand mixtures
Medium to coarse-grained sand
Fine-grained silty sand
Bedrock
Dissolved Plume
Source: Performance Monitoring of MNA Remedies for VOCs in Ground Water (EPA. 2004a)
Ground Water Technical Considerations during the Five-Year Review Process
Ground Water Forum Issue Paper 21
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Figure 2: Hydrogeologic CSM Example Cross Section
NNE
ssw
Legend
Roza 3
Conceptual diagram - not to scale
Potential High
Concentration Source
(DNAPL residual or
sorbed/diffused TCE mass)
TCE in water or soil gas
10-100 ppb
Observed
Potential/
Inferred
1-10 ppb
Observed
CpGp Potential/
o ° Inferred
Source: EPA. 2008b. Interim Record of Decision, Moses Lake Wellfield Superfund Site, Moses Lake, Washington
22 Ground Water Forum Issue Paper
Water Technical Considerations during the Five-Year Review Process
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Figure 3: Groundwater/Surface Water CSM Example
Conceptual Site Model
\(MlUS|)herie
Deposition
Rh'erbank
Imhistiiiil Erosion
I ^urreu
I
tlvtt'liun lliro
C
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17. KEY TECHNICAL RESOURCES FOR FYRS AT
GROUNDWATER SITES
Because web links tend to change over time, an attempt
has been made to include enough information about
each document to facilitate web searches.
17.1 General Groundwater References
EPA, 1990. Handbook: Ground Water - Volume 1: Ground
Water and Contamination. (EPA 625690016a). Available
at: http://www.epa.gov/ncepihom/
U.S. Geological Survey, 1998. Basic Ground-Water'Hydrology.
(Water Supply Paper 2220). Available at: http://pubs.
er.usgs.gov/usgspubs/wsp/wsp2220
17.2 EPA Five-Year Review Guidance
EPA, 2001. Comprehensive Five-Year Rem'ew Guidance. (EPA
540-R-01-007, OSWERNo. 9355.7-03B-P). Available at:
http://www.epa.gov/superfund/accomp/5year/index.htm
EPA, 2011. Recommended Evaluation of Institutional
Controls: Supplement to the "Comprehensive Five-Year Review
Guidance." (OSWER Directive 9355.7-18, September).
Available at: http://www.epa.gov/superfund/cleanup/
postconstruction/641333.pdf
EPA, 2012. AssessingProtectiveness at Sites for Vaporlntrusion,
Supplement to the "Comprehensive Five-Year Review Guidance."
(OSWER Directive 9200.2-84, November). Available
at: http://www.epa.gov/superfund/cleanup/postcon-
struction/pdfs/VI FYR Guidance-Fmal-ll-14-12.pdf
17.3 Site Management Policy
EPA, 2008. Superfund Environmental Indicators Guidance:
Human Exposure Revisions. (OSRTI). March. Available
at: http://www.epa.gov/superfund/accomp/ei/pdfs/
final_ei_guidance_march_2008.pdf
EPA, 2009. Summary of Key Existing EPA CERCEA
Policies for Groundwater Restoration. (OWSER Directive
9283.1-33). June 2009. Available at: http://www.
epa.gov/superfund/health/conmedia/gwdocs/
pdfs/9283 l-33.pdf
EPA, 2011. Environmental Cleanup 'Rest Management Practices:
Effective Use of the Project Eife Cycle Conceptual Site Model.
(EPA 542-F-l 1-011) July 2011. Available at: http://epa.
gov/tio/download/remed/csm-life-cycle-fact-sheet-
final.pdf
EPA, 2011. Groundwater Road Map: Recommended Process
for Restoring Contaminated Groundwater at Superfund Sites.
(OSWER 9283.1-34). July 2011. Available at: http://
www.epa.gov/superfund/health/conmedia/gwdocs/
pdfs/gwroadmapfinal.pdf
NRG (National Research Council), 2012. Alternatives-for
Managing the Nation's Complex Contaminated Groundwater
Sites. National Academies Press. Available at: http://www.
nap.edu/catalog.php?record_id= 14668
17.4 Remedy Optimization
EPA, 2002. Pilot Project to Optimise Superfund-financedPump
and Treat Systems: Summary Report and Lessons Learned.
(EPA 542-R-02-008a-u). November 2002. Available
at: http://www.clu-in.org/download/remed/rse/
phase_ii_report.pdf
EPA, 2004. Action Plan for Ground Water Remedy Optimisa-
tion. (OSWER 9283.1-25). August. Available at: http://
www.epa.gov/superfund/cleanup/postconstruction/
action_plan.pdf
EPA, 2004. ITRC (Interstate Technology & Regulatory
Council), 2004. Remediation Process Optimisation: Identifying
Opportunities for Enhanced and More Efficient Site Remediation.
RPO-1. Washington, DC September. Available at: http://
www.itrcweb.org/GuidanceDocuments/RPO-l.pdf
EPA, 2004. What Is Remediation Process Optimisation and
How Can It Help Me Identify Opportunities for Enhanced
and More Efficient Site Remediation? Webinar sponsored
by: Interstate Technology and Regulatory Council.
September. Archived presentation available at: http://
www.clu-in.org/conf/itrc/rpo_092804/
EPA, 2007. A Cost Comparison Framework for Use in
Optimising Ground Water Pump and Treat Systems. (EPA
542-R-07-005). Available at: http://www.cluin.org/
download/remed/hyopt/542r07005.pdf
EPA, 2007. Optimisation Strategies for Eong-Term Ground
Water Remedies (with Particular Emphasis on Pump and Treat
Systems). (EPA 542-R-07-007). Available at: http://www.
cluin.org/download/remed/hyopt/542r07007.pdf
EPA, 2012. National Strategy to Expand Superfund Optimi-
sation Practices from Site Assessment to Site Completion.
(OSWER Directive 9200.3-75, September). Available
at: http://www.epa.gov/oerrpage/superfund/cleanup/
postconstruction/2012strategy.pdf
24 Ground Water Forum Issue Paper
3 Water Technical Considerations during the Five-Year Review Process
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17.5 Groundwater Monitoring and Monitoring
Optimization
AFCEE, 2006. Monitoring and Remediation Optimisation
System (MAROS) User's Guide. March 2006 (in revision).
User's guide and software Version 2.2 available at:
http: //www. frtr.gov /decisionsupport/DST_Tools/
maros.htm
Version 3.0 available at: http://old.gsi-net.com/en/
software/free-software/maros-30.html
EPA, 1991. Handbook of Suggested Practices for the
Design and Installation of Ground-Water Monitoring Wells.
(EPA/600/4-89/034). Available at: http://www.epa.
gov/oust/cat Avwelldct.pdf
EPA, 1996. Low-Flow (Minimal Drawdown) Ground-Water
Sampling Procedures. (EPA/540/S-95/504). April 1996.
Available at: http://www.epa.gov/superfund/remedy-
tech/tsp/download/Iwflw2a.pdf
EPA, 2002. Ground-Water Sampling Guidelines for Superfund
andRCRA Project Managers. (EPA 542-S-02-001). May
2002. Available at: http://www.epa.gov/superfund/
remedytech/tsp/download/gw_sampling_guide.pdf
EPA, 2004. Guidance for Monitoring at Hazardous Waste
Sites: Framework for Monitoring Plan Development and
Implementation. (OSWER Directive No. 9355.4-28).
Available at: http://www.epa.gov/superfund/policy/
pdfs7dir9355.pdf
EPA, 2005. Roadmap to Long-Term Monitoring Optimisation.
(EPA 542-R-05-003, May 2005). Available at: http://
www.epa.gov/tio/download/char/542-r-05-003.pdf
17.6 Pump and Treat
EPA, 1994. Methods for Monitoring Pump-and-Treat Perfor-
mance. (EPA/600/R-94/123). Available at: http://www.
epa.gov/rlOearth/offices/oea/gwf/issue20.pdf
EPA, 2002. Elements for Effective Management of Operat-
ing Pump and Treat Systems. (OSWER 9355.4-27FS-A).
Available at: http://www.cluin.org/download/remed/
rse/factsheet.pdf
EPA, 2005. Cost-Effective Design of Pump andTreatSystems.
(OSWER 9283.1-20FS, EPA 542-R-05-008). Available
at: http://www.cluin.org/download/remed/hyopt/
factsheets/cost-effective_design.pdf
EPA, 2005. Effective Contracting Approaches for Operating
Pump and Treat Systems. (OSWER 9283.1-21FS, EPA
542-R-05-009). Available at: http://www.clum.org/
download/remed/hyopt/factsheets/contracting.pdf
EPA, 2005. O&M Report Template for Ground Water
Remedies (With Emphasis on Pump and Treat Systems).
(OSWER 9283.1-22FS, EPA 542-R-05-010). Available
at: http://www.epa.gov/superfund/action/postcon-
struction/omtemplate.pdf
EPA, 2008. A Systematic ApproachforEvaluation of Capture
Zones at Pump and Treat Systems. (EPA/600/R-08/003).
Available at: http://cfpub.epa.gov/si/si_public_
record Report.cfm?dirEntryId = 1 87788&C-
FID = 185702309&CFTOKEN=43140093&)session-
id=86304823e89c24cfd2d26467575723747969
17.7 Monitored Natural Attenuation
EPA, 1998. Technical Protocol for Evaluating Natural
Attenuation of Chlorinated Solvents in Ground Water.
(EPA/600/R-98/128). Available at: http://www.epa.
gov/tio/download/remed/pro tocol.pdf
EPA, 1999. Use of Monitored Natural Attenuation at
Superfund, RCRA Corrective Action, and Underground Storage
Tank Sites. (EPA/540/R-99/009, OSWER 9200.4-17P).
Available at: http: / /www.epa.gov/OUST/directiv /
d9200417.htm
EPA, 2004. Performance Monitoring of MNA Remedies for
VOCsm GroundWater. (EPA/600/R-04/027). Available
at: http://nepis.epa.gov/Adobe/PDF/10004FKY.pdf
EPA, 2011. An Approach to Evaluating the Progress of
Natural Attenuation in Groundwater. (EPA 600/R-11/204).
December 2011. Available at: http://nepis.epa.gov/
Adobe/PDF/PlOODPOE.pdf
17.8 Vapor Intrustion
EPA, 2002. OSWER Draft Guidance for Evaluating the
Vapor Intrusion to Indoor Air Pathway from Groundwater
and Soils (Subsurface Vapor Intrusion Guidance). (EPA
530-D-02-004). Available at: http://epa.gov/osw/
hazard/correctiveaction/eis/vapor.htm
Ground Water Technical Considerations during the Five-Year Review Process
Ground Water Forum Issue Paper 25
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EPA, 2012. A Citizen's Guide to Soil Vapor Extraction
and Air Sparging. (OSWER 542-F-12-018). Available at:
http://www.clu-in.org/download/citizens/a_citizens_
guide_to_soil_vapor_extraction_and_air_sparging.pdf
17.9 Groundwater/Surface Water Interactions
EPA, 2000. Proceedings of the Ground-Water/Surface-Wa-
ter Interactions Workshop. (EPA/524/R-00/007). July.
Available at: http://www.epa.gov/superfund/remedy-
tech /tsp /download /gwsw 7gwsw_partl.pdf
http://www.epa.gov/superfund/remedytech/tsp/
download/gwsw/ gwsw_part2.pdf (Poster Session
Abstracts)
http://www.epa.gov/superfund/remedytech/tsp/
download7gwsw7gwsw_part3.pdf (Appendices)
EPA, 2008. ECO Update/Ground WaterForum Issue Paper:
Evaluating Ground-Water/ Surf ace-Water Transition Zones
in Ecological Risk Assessments. (EPA 540-R-06-42). July.
Available at: http://www.epa.gov/oswer/riskassess-
ment/ecoup/pdf 7eco_update_08.pdf
U.S. Geological Survey, 1998. Ground Water and Surface
Water; a Single Resource. Circular 1139. Washington:
Government Printing Office. 1998. Available at: http://
pubs.usgs.gov/circ/circll39/
17.10 Alternate Concentration Limits
EPA, 2005. Alternate Concentration Eimits (ACE's) in
Superfund Cleanups. (OSWER Directive 9200.4-39).
Available at: http://www.epa.gov/superfund/health/
conmedia/gwdocs/acls.htm
17.11 Contaminated Sediment
EPA, 2005. Contaminated SedimentRemediation Guidance for
Hazardous Waste Site. (EPA-540-R-05-012). December.
Available at: http://www.epa.gov/superfund/health/
conmedia/sediment /guidance, htm
17.12 Closeout of Groundwater Cleanups
EPA, 1992. Methods for Evaluating the Attainment of Cleanup
Standards, Vol. 2: Ground Water. (EPA/230-R-92-014).
Available at: http://www.epa.gov/superfund/resources/
remedy /pdf/230r-92014-s.pdf
EPA, 2013. Guidance for Evaluating Completion of Ground-
water Restoration Remedial Actions. (OSWER 9355.0-
129). November. Available at: http://www.epa.gov/
superfund/health/conmedia/gwdocs/pdfs/Groundwa-
terAttainmentPolicy-finalsigned-ll%2025%202013.pdf
EPA, 2014. Groundwater Remedy Completion Strategy.
(OSWER Directive 9200.2-144). May. Available at:
http://www.epa.gov/superfund/health/conmedia/gwdocs/
pdfs/EPA_Groundwa ter_Remedy_Completion.pdf
EPA, 2014. Groundwater Statistics Tool (OSTRTI).
August. Available at: http://www.epa.gov/superfund/
health/conmedia/gwdocs/download/GW_Stats_
Tool 08112014.final.xlsm
EPA, 2014. Recommended ApproachforEvaluating Completion
of Groundwater Restoration Remedial Actions at a Monitoring
Well. (OSWER 9283.1-44). August. Available at: http://
www.epa.gov/superfund/health/conmedia/gwdocs/
pdfs /GWcompletion-recommendedapproach-fi-
nal-8.4.2014.pdf
17.13 RCRA Groundwater Guidance
EPA, 1986. Final RCRA Comprehensive Ground-Wa-
ter Monitoring Evaluation (CME) Guidance Document.
December. Available at: http://www2.epa.gov/sites/
production /files /2013-10 /documents /frcracmed-
oc-rpt.pdf
EPA, 1988. Operation and Maintenance Inspection Guide
(RCRA Ground-Water Monitoring Systems), Final. March.
Available at: http://www2.epa.gov/sites/production/
files/documents/rcrainspecguid-rpt.pdf
EPA, 1992. RCRA Ground-WaterMonitoring.FJraftTechni-
cal Guidance. November. Available at: http://www.epa.
gov/region09/qa/pdfs/rcra_gwm92.pdf
EPA, 2004. Handbook of Groundwater Protection
and Cleanup Policies for RCRA Corrective Action.
(EPA530-R-04-030). Available at: http://www.epa.gov/
osw/hazard/correctiveaction/resources/guidance/
pdfs/gwhb041404.pdf
26 Ground Water Forum Issue Paper
3 Water Technical Considerations during the Five-Year Review Process
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17.14 Useful Websites
EPA's Five-Year Reviews web page (links to guidance,
supplements, fact sheets, reports to Congress, etc.)
http://www.epa.gov/superfund/fiveyearreview/
EPA's Technical Support Project Ground Water Forum
http://www.epa.gov/superfund/remedytech/tsp/issue.
htm#GWF
Topics Include:
Groundwater Sample Preservation and In Situ Chemical
Oxidation Sites
Evaluating Ground-Water/Surface-Water Transition
Zones in Ecological Risk Assessments
Fingerprint Analysis of Contaminant Data
Phytoremediation of Contaminated Soil and Ground
Water at Hazardous Waste Sites
Steam Injection for Soil And Aquifer Remediation
How Heat Can Enhance In-Situ Soil and Aquifer Re-
mediation
Natural Attenuation of Hexavalent Chromium in
Groundwater and Soils
Suggested Operating Procedures for Aquifer Pumping
Tests
Chemical Enhancements to Pump-and-Treat Remedi-
ation
In-Situ Bioremediation of Contaminated Ground Water
Groundwater Sampling Guidelines
CLU-IN: EPA's Hazardous Waste Cleanup Information
http: / /www.clu-in.org/. The DNAPL Contaminant
Focus Area on CLU-IN has over a thousand references:
http://www.clu-in.org/dnapl
FRTR: Federal Remediation Technologies Roundtable
http: / /www. frtr.gov/
ITRC: Interstate Technology and Regulatory Council
http://www.itrc.web.org
Ground Water Technical Considerations during the Five-Year Review Process
Ground Water Forum Issue Paper 27
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