Groundwater Remedies
Selected at Superf und Sites
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Solid Waste EPA-542-R-01 -022
and Emergency Response January 2002
(5102G) www.epa.gov/TIO
clu-in.org/groundwater
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Contents o
rt
Section Page
Acronyms iii
Notice .. iv o
Introduction.. ...1
Acknowledgment v
Executive Summary vi
Overview 1 o>
Remedy Selection Background 1
Remedies Addressed in This Report 1
CD
Sources of Information for This Report... ... 2
c-h
to
Definitions of Specific Treatment Technologies 2 c
Section 1: Overview of Remedy Decisions 4
Croundwater Treatment and MIMA RODS Signed by Year 4
Croundwater Remedy Selection at Sites on the NPL 5
Croundwater P&T Remedy Optimization 7
Section 2: Common Croundwater Remedies 8
Croundwater Treatment RODS 8
Croundwater P&T Remedy Selection 9
Selection of MIMA 9
Selection of in Situ Treatment 11
Section 3: in Situ Croundwater Treatment Technologies 13
Most Common Technologies for In Situ Croundwater Treatment 14
Contaminants Addressed 15
ROD Seduence 15
Future Data Needs 16
Section 4: References and Data Sources 17
APPENDICES
A Croundwater Remedies Selected in Records of Decision at Sites on
the National Priorities List
B identification of Remedy and Record of Decision Types for
Superfund Remedial Actions
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TABLES
co
Table 1 Types of Remedies 1
Table 2 Types of croundwater Remedies 2
Q.
Table 3 Years in operation for 67 Superfund Remedial Action P&T Systems.... 7
Table 4 FRTR case Studies for croundwater P&T, in Situ Treatment,
and MIMA.. ..13
0)
Tables Superfund Remedial Actions: in Situ Croundwater Treatment
c8 Technologies at 81 Sites Selecting These Technologies
(FY1982-FY1999).. ..14
FIGURES
_
Figure 1 RODS Selecting croundwater and Source Control Remedies
(FY 1982 - FY 1999) 4
Figure 2 Remedy Types Selected at Sites on the National Priorities List
o (FY 1982 - FY 1999) 5
Figure 3 Sites with P&T, in Situ Treatment, or MIMA selected as Part of a
Croundwater Remedy (FY 1982 - FY 1999) 6
Figure 4 RODS Selecting MiMA-only and RODS Selecting croundwater
Treatment (FY 1982 - FY 1999) 8
Figure 5 Selection of P&T for Superfund Remedial Actions
(FY 1986 - FY 1999) 9
Figure 6 Selection of MIMA for Superfund Remedial Actions
(FY 1986 - FY 1999) 10
Figure 7 Trend in the Selection of MIMA for Superfund Remedial Actions
(FY 1986 - FY 1999) 10
Figure 8 Selection of in Situ Croundwater Treatment for Superfund
Remedial Actions (FY 1986 - FY 1999) 11
Figure 9 Trend in the Selection of in Situ Croundwater Treatment for
Superfund Remedial Actions (FY 1986 - FY 1999) 12
Figure 10 Superfund Remedial Actions: Cumulative Trends for in Situ
Croundwater Treatment Technologies (FY 1982 - FY 1999) 14
Figure 11 Contaminants Treated by in Situ Croundwater Treatment
Technologies for Superfund Remedial Actions (FY 1982 - FY 1999) 15
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Acronyms I
ASR
BTEX
CERCLIS 3
CLU-IN
EPA
ESD
FRTR
MNA
NA/NFA
NAPL
NPL
Annual Status Report
Benzene, toluene, ethylbenzene,
and xylene
Comprehensive Environmental
Response, Compensation, and
Liability Information System
EPAs hazardous waste CLeanUp
INformation system
U.S. Environmental Protection
Agency
Explanation of significant
differences
Federal Remediation Technologies
Roundtable
Fiscal year
Monitored natural attenuation
No action/no further action
Nonaqueous phase liquid
National Priorities List
OERR
OSC
OSWER
OU
P&T
PAH
pdf
PRB
ROD
RPM
RSE
SVE
svoc
TIO
VEB
VOC
Office of Emergency and
Remedial Response
On-scene coordinator
Office of Solid Waste and
Emergency Response
Operable unit
Pump and treat
Polycyclic aromatic hydrocarbon
Portable document format
Permeable reactive barrier
Record of Decision
Remedial Project Manager
Remedial System Evaluation
Soil vapor extraction
Semivolatile organic compound
Technology Innovation Office
Vertical engineered barrier
Volatile organic compound
I
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Notice
This document was prepared by the U.S.
Environmental Protection Agency's Technology
Innovation Office under EPA Contract Number
68-W-99-020. Mention of trade names or
commercial products does not constitute
endorsement or recommendation for use.
For more information about this project, please
contact:
U.S. Environmental Protection Agency
Technology Innovation Office
1200 Pennsylvania Avenue, N.W.
MS5102G
Washington, DC 20460
Telephone: (703) 603-9910
http ://clu-in. org/groundwater
or
www.epa.gov/TIO
A portable document format (pdf) version of
Groundwater Remedies Selected at Superfund Sites
is available for viewing or downloading from the
Hazardous Waste Cleanup Information (CLU-IN)
web site at http://clu-in.org/groundwater. A printed
copy can also be ordered directly from CLU-IN.
If you do not have access to the Internet, a printed
version of this document can be obtained from:
National Service Center for Environmental
Publications
U.S. Environmental Protection Agency
P.O. Box 42419
Cincinnati, OH 45242-2419
Telephone: (513) 489-8190 or (800) 490-9198
Fax: (513)489-8695
When ordering, refer to document number EPA-
542-R-01-022.
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Acknowledgment
This document was prepared for EPA's Technology
Innovation Office under Contract Number 68-W-
99-020. Special acknowledgment is given to the
federal and state staff and other remediation
professionals for individual sites, who provided the
detailed information presented in this document.
Their cooperation and willingness to share their
expertise on treatment technologies encourages the
application of those technologies at other sites.
Q,
IQ
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X
Executive Summary
Over a 17-year period from 1982 through 1999
(years discussed in this report are fiscal years [FY]),
more than 2,200 Records of Decision (RODs)
have been signed for 1,451 Superfund sites,
including 989 RODs addressing the remediation
of contaminated groundwater at 787 Superfund
sites. Groundwater remediation continues to be a
priority for the U.S. Environmental Protection
Agency (EPA), and remedies that have been
specified in RODs for groundwater remediation
include treatment (including groundwater pump
and treat [P&T] and in situ treatment) and
monitored natural attenuation (MNA).
The Technology Innovation Office of the EPAs
Office of Solid Waste and Emergency Response
(OSWER) prepared this report to document the
selection of groundwater treatment and MNA
remedies at Superfund remedial action sites. The
report presents data on groundwater treatment and
MNA remedy decisions and analyzes trends in these
decisions over time.
The focus of this report is on groundwater
treatment and MNA remedies that result in a
reduction of contaminant concentrations or
mobility. Groundwater containment and
groundwater-other remedies are not addressed in
this report.
The findings of this report on the selection of
groundwater treatment and MNA remedies are:
Major Findings:
' The selection of P&T as a groundwater remedy
has steadily decreased since 1986.
The selection of in situ treatment and MNA
as groundwater remedies has increased since
1986, with the exception of 1999, when
selection of MNA remedies decreased
significantly.
Remedy Types:
Between 1982 and 1999, at least one
groundwater remedy was selected at more than
half (54%) of Superfund sites.
P&T is the most frequently selected remedy
at groundwater remedy sites, followed by
MNA and in situ treatment.
Remedy Selection Trends:
The percentage of groundwater remedy RODs
that selected only P&T has decreased from
92% in 1986 to 30% in 1999.
The percentage of groundwater remedy RODs
selecting only MNA has increased from 8%
in 1986 to 23% in 1999. In 1998, the
percentage of MNA-only RODs peaked at
44% but declined to 23% in 1999.
The percentage of groundwater remedy RODs
selecting in situ treatment increased sharply
from 1995 (9%) through 1999 (35%). This
rapid growth followed a slow climb from 1986
(0%) to 199 5 (9%).
in Situ Treatment Technologies:
' The in situ groundwater treatment technologies
most commonly used for Superfund remedial
actions are air sparging and bioremediation.
The in situ groundwater treatment technology
used most frequently to treat volatile organic
compounds is air sparging, while semi-volatile
organic compounds are most frequently
treated using bioremediation.
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Overview
introduction
This report presents the results of analyses of:
the types of ground-water remedies selected at
Superfund sites,
the trends in the selection of groundwater
remedies,
the technologies used to perform in situ
treatment of groundwater, and
the contaminants treated using in situ
groundwater treatment technologies.
This report focuses on groundwater treatment or
MNA remedies selected in 989 RODs or ROD
amendments through 1999. Groundwater
treatment and MNA remedies reduce contaminant
concentrations or decrease their mobility.
However, MNA does not generally satisfy the
CERCLA preference for treatment because it is
not an engineered technology (Ref. 12, page 17).
Detailed information about the technologies used
to perform in situ groundwater treatment is
presented for 95 treatment projects at 81 sites.
Remedy Selection Background
RODs for Superfund remedial actions may
address sources of contamination, such as soil,
sludge, sediments, and solid-matrix wastes. Such
"source control" RODs select "source control
remedies." RODs also may address groundwater.
RODs for Superfund remedial actions that
address groundwater are "groundwater" RODs.
Appendix B to this document is a detailed
description of the methodology used to identify
ROD types, including detailed definitions of
TABLE 1. TYPES OF REMEDIES
Source Control Remedy
Addresses a contaminant source, such as
soil, sludge, sediment, or solid waste.
Can include source treatment, containment,
or other source remedies such as access
restrictions and population relocation.
Groundwater Remedy (See Table 2 for more
detail on groundwater remedies)
Remediation of a contaminated aquifer
Can include pump and treat, in situ treatment,
monitored natural attenuation, containment
using vertical engineered barriers, or
groundwater-other remedies such as
providing an alternate drinking water supply.
"source control," "groundwater," and other
remedy types. Table 1 presents a brief overview
of these remedy types.
Throughout this report, the term "groundwater
remedies" refers to P&T, in situ treatment, and
MNA, and does not include groundwater
containment and groundwater-other remedies,
unless specified. Table 2 provides brief descriptions
of groundwater remedies, including groundwater
containment and groundwater-other remedies.
Remedies Addressed in This Report
EPAs Technology Innovation Office (TIO) has
historically provided information about innovative
and conventional remedies at Superfund sites in
the report Treatment Technologies for Site Cleanup:
Annual Status Report (Tenth Edition) (ASR). The
ASR is available on line at http://clu-in.org/asr.
Currently in its tenth edition, the ASR has focused
primarily on source control treatment and in situ
groundwater treatment, and has not addressed
groundwater P&T or MNA remedies.
TIO continues to advocate more effective, less
costly approaches (i.e., "smarter solutions") to
cleaning up hazardous waste sites. This report
provides information about the use of groundwater
treatment and MNA remedies at Superfund sites
to site managers, technology service providers, and
other stakeholders to assist them in identifying sites
where particular groundwater remedies have been
selected. In addition, EPA can also use the
information in this report to track groundwater
remedy selections and assist site managers in their
quest to optimize past or future remedies with new
information and knowledge acquired from
analyzing all remedies in the program.
Groundwater containment and groundwater-
other remedies are not addressed in this report.
Groundwater containment remedies, such as
vertical engineered barriers, are not a focus of this
report because these remedies have been discussed
in detail in the ASR. Groundwater-other remedies
(see Table 2, page 2), such as well-drilling
prohibitions and alternate drinking water supplies,
are not a focus of this report because these
remedies, while being protective, typically do not
directly result in a reduction in contaminant
concentrations or a decrease in contaminant
mobility. In addition, the information needed to
identify groundwater-other remedies is not
currently available. Appendix B contains a
complete list of remedies that are considered
groundwater-other.
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A portable document format (pelf) version of this
report is available for viewing or downloading from
the Hazardous Waste Cleanup Information (CLU-
IN) web site at http://clu-in.org/groundwater. To
facilitate access to more detailed information about
the remedies selected at specific sites and in specific
RODs, the online pdf version of this report also
contains links to downloadable spreadsheets
containing supporting data for figures presented in
this report.
TABLE 2. TYPES OF CROUNDWATER REMEDIES
Pump and Treat (P&T)
Extraction of groundwater from an aquifer
and treatment above ground.
Extraction usually is done by pumping
groundwaterfrom awell ortrench. Avariety
of technologies maybe used in performing
treatment.
In Situ Treatment
Treatment of groundwater in place without
extracting it from an aquifer.
Specific treatment technologies used for
in situ groundwater treatment that are
discussed in this report are:
- Air sparging
- Bioremediation
- Chemical treatment
- Dual-phase extraction
- In-well air stripping
- Permeable reactive barriers
- Phytoremediation
Monitored Natural Attenuation (MNA)
The reliance on natural attenuation
processes (within the context of a carefully
controlled and monitored approach to site
cleanup) to achieve site-specific remediation
objectives within a reasonable time frame.
Natural attenuation processes include a
variety of physical, chemical, and
biological processes.
Groundwater Containment
Containment of groundwater through the
use of a vertical, engineered, subsurface,
impermeable barrier.
Groundwater containment may be
performed using a variety of barrier materials
and barrier construction techniques.
Groundwater-Other
Groundwater remedies that do not fall into
the categories of groundwater P&T, in situ
treatment, MNA, or containment remedies.
Can include a variety of remedies, such as
water use restrictions and alternate water
supply.
Sources of information for This Report
For this report, information about remedy selections
was gathered from the 2,292 RODs and ROD
amendments for Superfund sites that were signed
from 1982 through 1999, of which 989 selected
groundwater treatment or MNA remedies.
Information about specific technologies used for and
contaminants treated by in situ groundwater treatment
remedies initially was compiled from RODs, ROD
amendments and those Explanations of Significant
Differences (ESDs) included in the Comprehensive
Environmental Response, Compensation, and Liability
Information System (CERCLIS 3), EPAs Superfund
tracking system. Data on project status in the
CERCLIS 3 provided more detailed information about
the specific portion of the remedy involving in situ
groundwater treatment technologies. EPA then verified
and updated the information on in situ technologies
through interviews with remedial project managers
(RPMs), On-Scene Coordinators (OSCs), and other
contacts for each site. Therefore, information in this
report may differ from information in the CERCLIS
3 database. Such differences occur when changes are
made in the remedy during the design phase of the
project. The changes may not require official
documentation (that is, a ROD amendment or ESD),
and hence, would not be recorded in CERCLIS 3 but
would be obtained from interviews.
Definitions of Specific Treatment
Technologies
This document reports on the selection of groundwater
remedies and the use of specific in situ groundwater
treatment technologies. This introduction provides
brief definitions of seven types of in situ groundwater
treatment technologies, as they are discussed in this
document. The groundwater treatment technology
definitions are based on the introduction to the ASR.
The ASR can be viewed at http://clu-in.org/cisr.
Sketches are provided for some of the technologies.
in Situ Groundwater Treatment
Technologies
AIRSPARGING involves the injection of air or oxygen
through a contaminated aquifer. Injected air traverses
horizontally and vertically in channels through the soil,
creating an underground stripper that removes volatile
and semivolatile organic contaminants by volatilization.
The injected air helps to flush the contaminants into
the unsaturated zone. Soil vapor extraction (SVE)
usually is implemented in conjunction with air sparging
to remove the generated vapor-phase contamination
from the vadose zone. Oxygen present in the air
added to the contaminated groundwater and vadose-
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Model of an Air Sparging System
Model of a Permeable Reactive Barrier
Vapor Extraction Well
tl
zone soils also can enhance biodegradation of
contaminants below and above the water table.
With IN SITU GROUNDWATER
BIOREMEDIATION, substrates, nutrients, nonnative
bacteria, or an oxygen source (for aerobic processes),
are pumped into an aquifer through wells to enhance
biodegradation of contaminants in groundwater.
Specific types of in situ groundwater bioremediation
include biosparging and bioventing.
DUAL-PHASE EXTRACTION, also known as multi-
phase extraction, uses a vacuum system to remove
various combinations of contaminated groundwater,
immiscible contaminants, and vapors from the vadose
and saturated zone. The system lowers the water table
around the well, exposing more of the vadose zone.
Contaminants in the newly exposed vadose zone are
then accessible to vapor extraction. The extracted
vapors or liquid-phase organics and groundwater are
collected, separated, and treated above ground.
CHEMICAL TREATMENT, also known as chemical
reduction/oxidation, typically involves reduction/
oxidation (redox) reactions that chemically convert
hazardous contaminants to nonhazardous or less toxic
compounds that are more stable, less mobile, or inert.
Redox reactions involve the transfer of electrons from
one compound to another. Specifically, one reactant
is oxidized (loses electrons) and one is reduced (gains
electrons). Cyanide oxidation and dechlorination are
examples of chemical treatment.
For IN-WELL AIR STRIPPING, air is injected
into a double screened well, lifting the water in the
well and forcing it out the upper screen, which causes
additional water to be drawn into the lower screen.
Volatile organic compounds (VOCs) in the
contaminated groundwater are transferred from the
dissolved phase to the vapor phase in air bubbles,
which rise to the water surface, as vapors are drawn
off and treated. The treated groundwater is forced
into the unsaturated zone.
PERMEABLE REACTIVE BARRIERS (PRBs), also
known as passive treatment walls, are installed across
the flow path of a contaminated groundwater plume,
Direction of
Groundwater Flow
nfining Layer mssses'^' V . .-'
uitarcfi
allowing the passage of water, while treating the
contaminants with zero-valent iron, chelators, sorbents,
or microbes. The contaminants are either degraded
or retained in a concentrated form by the barrier
material, which may require periodic replacement.
PHYTOREMEDIATION is a process that uses plants
to remove, transfer, stabilize, or destroy contaminants
in soil, sediment, and groundwater. The mechanisms
of phytoremediation include enhanced biodegradation
in the rhizosphere (soil or groundwater immediately
surrounding plant roots), phytoextraction (also known
as phytoaccumulation, the uptake of contaminants by
plant roots and the translocation and accumulation of
contaminants into the shoots and leaves of plants),
phytodegradation (metabolism of contaminants within
plant tissues), and phytostabilization (production of
chemical compounds by plants to immobilize
contaminants at the interface of roots and soil).
Phytoremediation applies to all biological, chemical,
and physical processes that are influenced by plants
(including the rhizosphere) and that aid in the cleanup
of contaminated substances. Plants can be used in
site remediation, both through the mineralization of
toxic organic compounds and through the accumulation
and concentration of heavy metals and other inorganic
compounds into aboveground shoots.
Phytoremediation may be applied in situ or ex situ,
to soils, sludges, sediments, other solids, or
groundwater.
Model of Phytoremediation
Photosynthesis-^T-^ xylem
hloem
Photosynthesis + 02
Transpiration
Respiration
Root respiration/^
CO + H202
Mineralization
Uptake (and
contaminant
removal)
Transpiration
Organic 1 ~~s.
chemicals Uptake j
CxHy0z 02+exduates
e.g., CH3C OOH
radation
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Groundwater containment and groundwater-other
remedies were not considered for Figure 1 (page 4)
because they are not the focus of this report and the
data needed to identify groundwater-other remedies
were not available. In addition, RODs selecting only
NA/NFA remedies are not included in Figure 1 (page
4). RODs identified as having only source control
remedies may in fact have groundwater containment
or groundwater-other components to their remedies.
For example, a site selecting solidification/stabilization
for a source control remedy and an alternate water
supply for a groundwater remedy is classified as only
having a source control remedy because the
groundwater remedy is groundwater-other, which is
not discussed in detail in this report.
RODs may have selected only groundwater remedies
when the only media requiring a remedy at a site was
groundwater or the remediation of contaminant
sources was addressed in a separate ROD. RODs
selecting both source and groundwater remedies did
not necessarily address related source and groundwater
media (i.e., remediation of both contaminated
groundwater and sources contributing to that
groundwater contamination). For example, at the
Fort Ord site in Marina, California (CERCLIS ID
number CA7210020676) a ROD signed in 1997
selected excavation and on-site disposal of soil and
debris from several areas of the site (a source control
remedy) and treatment of groundwater contamination
in a separate area of the site (a groundwater treatment
remedy). In this case, a single ROD selected separate
source control and groundwater remedies for portions
of the site that were not directly related.
Ground water Remedy Selection at Sites
on the A/PL
As shown in Figure 2, over half of all NPL sites
(787 of 1,451) selected some type of groundwater
remedy, including groundwater treatment (P&T or
in situ treatment), MNA, containment, or
groundwater-other remedies. Sites for which only a
source control remedy was selected comprise 22%
No ROD Issued Through FY
1999 (236)
17%
Figure 2. Remedy Types Selected at Sites on the
National Priorities List (FY 1982 - FY 1999)
Total Number of Sites = 1,451
Sites With Groundwater Remedies = 787 (54%)
MNAฐ (92)
6%
P&T and In Situ Treatment of
Groundwater (62)
4%
Groundwater-Other Remedy
Only b (33)
2%
In SituTreatment of
Groundwater8 (19)
1%
No Action or No Further
Action (102)
7%
Source Control (326)
22%
roundwater Containment1 (5)
P&Tf (576)
41%
Sources: 1,2,3,4,5,6,8. Data sources are listed in the References and Data Sources Section on p. 17.
PejrT= Pump and treat
MNA = Monitored natural attenuation
a. Includes sites where a source control remedy was selected but no groundwater PeJrT, in situ treatment, MNA, or
containment remedy was selected. Insufficient data were available to identify sites selecting both source control and
groundwater-other remedies; therefore, some of the 326 source control sites may also have groundwater-other remedies.
b. Includes only sites where groundwater-other remedies were the only remedies selected for the site.
c. Does not include sites selecting both MNA andP&Tor in situ treatment ofgroundwater.
d. Does not include sites selectingPeJrT, in situ treatment of groundwater, or MNA.
e. Does not include sites selecting both P&Tand in situ groundwater treatment.
f. Includes both PeJrT alone andP&T with any other remedy (except in situ groundwater treatment).
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en
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P&T systems alone were selected for 521 sites,
MNA alone for 92 sites, and in situ groundwater
treatment alone for 16 sites.
When two types of groundwater remedies were
used at the same site, a P&T system was used
most frequently with MNA (55 sites). Next in
frequency of use was a P&T system with in situ
treatment (48 sites). For 14 of the 749 sites, three
types of groundwater remedies were used at the
same site. At the majority of sites where a
groundwater remedy was selected, some form of
treatment was included. P&T or in situ treatment
was included in the selected remedy at 88% (657)
of the sites, while sites selecting only MNA
comprised only 12% of sites.
The online version of this report includes a
downloadable spreadsheet to help site managers,
the regulated community, and remediation
professionals identify sites at which a particular
remedy type has been selected. The spreadsheet
contains information for each NPL site where a
ROD has been issued, including the site name,
location, and site type. The electronic version of
this report is available on EPAs CLU-IN web site
at http://clu-in.org/groundwater.
Ground water P&T Remedy Optimization
Once remediation systems have been functioning
for a period of time, opportunities may exist to
optimize the system, particularly if they are long-
term remedies. The purpose of optimization is
to identify potential changes that will improve the
effectiveness of a system and reduce operating
costs without compromising the protectiveness
of the remedy or achievement of other response
objectives.
EPA recognizes that long-term remedial approaches
should not remain static, that conditions change
over time, and that better technologies, tools, and
strategies evolve, which allow for continuous
improvement of remedy performance. In OSWER
Directive No. 9200.0-33, Tmnsmittal of Final FYOO
- FY01 Superfund Reforms Strategy, dated July 7,
2000, EPA outlined a commitment to optimize
Fund-lead P&T systems at Superfund sites.
To fulfill this commitment, EPA is gathering
information on Fund-lead P&T systems and selecting
sites for a Remediation System Evaluation (RSE).
Fund-lead P&T systems include systems that are
either EPA-lead or State-lead that are funded from
the Superfund Program. EPA performed an RSE
on up to 20 Fund-lead groundwater P&T systems
during 2001.
The results of this initiative are documented in
the report Groundwater Pump-and-Treat Systems:
Summary of Selected Cost and Performance
Information at Superfund-Financed Sites (Ref. 10,
page 17), which is available on line at http://clu-
in.org. This report was used to analyze the status
and age of P&T systems. Additional information
on RSE and optimization of remedies is available
at http://www.frtr.gov/optimization. This site
includes information on optimization tools and
techniques, including checklists that can be used
to identify optimization opportunities for specific
groundwater treatment technologies.
Table 3 shows the number of years the Fund-lead
P&T systems have been in operation. The average
age of the systems was approximately 5 years.
Opportunities for optimization have been found
in three areas of P&T systems: long-term
monitoring of their performance, well placement
and pumping rates, and the effluent stream
treatment technology. P&T systems, while
performing as designed and being protective, may
not always be operating in the most cost effective
manner. The longer a remedy has been operating,
the richer the performance data set available with
which to seek optimization opportunities in any
of the areas described in this section.
Table 3. Years in Operation
for 67 Superfund Remedial Action
P&T Systems
Years in Operation
0-5
Number of Systems
(Percent of Systems)
35 (52%)
5-10
28 (42%)
10- 15
4 (6%)
Total
Sources: 10. Data sources are listed in the References and
Data Sources Section on p. 17.
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Figure 5. Selection of P&T for
Superfund Remedial Actions (FY1986 - FY 1999)
100%
90%
80%
70%
60%
Percentage of
Groundwater 50%
RODsa
40%
30%
20%
10%
88% 90% 90%
88%
78%
73%
67%
70%
59%
P&T Only
P&T and Another Groundwater Remedy
(MNA or In Situ Treatment)
. In Situ Treatment or MNA, but Not P&T
16%
18%
17% 18%
8% 9%
13% ^
ซ. *
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999
Fiscal Year
Sources: 3, 4, 5, 6, 8. Data sources are listed in the References and Data Sources Section on p. 17.
P&T= Pump and treat
MNA = Monitored natural attenuation
a. Includes groundwater P&T, in situ treatment, and MNA remedies.
Groundwater containment andgroundwater-other remedies are not included.
ป
Q.
Groundwater P&T Remedy Selection
As a percentage of RODs selecting groundwater
remedies, RODs selecting P&T alone have been
decreasing. The percentage of groundwater RODs
selecting P&T in combination with another
groundwater remedy, and the percentage of
groundwater RODs not selecting P&T (i.e., those
selecting in situ treatment or MNA) has been
increasing. Figure 5 shows trends in the selection
of P&T remedies, both alone and in combination
with groundwater in situ treatment and MNA
remedies. In addition, this figure shows the trend
in the selection of groundwater remedies that do
not include P&T (i.e., the remedies that include in
situ groundwater treatment or MNA without P&T).
In 1986, RODS selecting only groundwater P&T
represented 92% of all groundwater RODs. This
percentage decreased to 30% in 1999. From
1986 to 1999, the selection of groundwater
remedies without P&T has increased. In 1986,
groundwater treatment and MNA remedies that
did not include P&T were selected in only 8% of
RODs. By 1999, that fraction increased to 53%.
The percentage of groundwater RODs that did
not select P&T exceeded the percentage of RODs
selecting P&T-only for the first time in 1998 and
again in 1999. Groundwater RODs selecting
P&T in combination with either in situ
groundwater treatment or MNA also increased
from 0% in 1986 to 18% in 1999.
Selection of MNA
Groundwater MNA is the reliance on natural
attenuation processes (within the context of a
carefully controlled and monitored approach to site
cleanup) to achieve site-specific remediation
objectives within a time frame that is reasonable,
compared with that offered by other, more active
methods. The "natural attenuation processes"
include a variety of physical, chemical, or biological
processes that, under favorable conditions, act
without human intervention to reduce the mass,
toxicity, mobility, volume, or concentration of
contaminants in soil or groundwater. These in
situ processes include biodegradation; dispersion;
dilution; sorption; volatilization; radioactive decay;
and chemical or biological stabilization,
transformation, or destruction of contaminants
(Ref. 12, page 17).
Since 1986, the fraction of groundwater RODs
selecting MNA, both alone and in combination with
P&T and in situ treatment, has increased. Figure
6 (page 10) compares the trends in the percentage
of groundwater RODs selecting only MNA to MNA
-------
-------
However, in 1999 this percentage decreased to
45%. This decrease coincides with the
publication of EPA guidance on the use of MNA
during 1999 (Ref. 12, page 17). This directive
was issued to clarify EPA's policy regarding the
use of MNA for the remediation of
contaminated soil and groundwater at sites
administered by EPA's OSWER, and contained
guidance for the implementation of MNA,
including guidance for:
the role of MNA in OSWER remediation
programs
demonstrating the efficacy of MNA through
site characterization
sites where MNA may be appropriate
reasonable time frames for achieving cleanup
goals using MNA
remediation of sources using MNA
performance monitoring and evaluation
using MNA
including contingency remedies as part of an
MNA remedy
Although no data that directly link the directive to
the decrease in selection of MNA were available,
the guidance may have influenced remedy
identification and selection. For example, the
directive provided a more specific definition of
MNA than was available in the past. Prior to
publication of the directive, some remedies
identified as MNA may not have met the definition
provided in the directive. Authors of 1999 RODs
may have identified remedies that they would have
previously identified as MNA as another remedy,
such as monitoring only or NA/NFA.
Selection of in Situ Treatment
In situ groundwater treatment is usually selected
in combination with P&T or MNA. Figure 8
compares the trends in the percentage of
groundwater RODs selecting only in situ treatment
with in situ treatment in combination with P&T
or MNA. The percentages in Figure 8 add up to
less than 100% for each year because groundwater
RODs not selecting in situ treatment are not
included in this figure. Figure 8 shows that the
percentage of groundwater RODs selecting in situ
Q.
Figure 8. Selection of in Situ Croundwater Treatment
for Superfund Remedial Actions (FY1986 - FY1999)
30%
20%
Percentage of
Grundwater
RODs9
10%
0%
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999
Fiscal Year
Sources: 3, 4, 5, 6, 8. Data sources are listed in the References and Data Sources Section on p. 17.
P&T= Pump and treat
MNA = Monitored natural attenuation
a. Includes groundwater P&T, in situ treatment, and MNA remedies.
Groundwater containment and groundwater-other remedies are not included.
--In
-In
Rf
6%
Situ Treatment Only
Situ Treatment and Another Groundwater
jmedy (P&T or MNA)
23%,
.'Co'V^vV ' 1370
/ lfc/0 f*'^S ss '
~...--''''e%
-------
treatment in combination with another
groundwater remedy has increased from 0% in
1986 to 13% in 1999. Prior to 1993, no
groundwater RODs selected in situ treatment as
the sole groundwater remedy. Since then, the
percentage of groundwater RODs selecting in situ
treatment alone has generally increased. Although
the percentage has varied significantly from year
to year, the overall trend has been an increase from
1% in 1993 to 23% in 1999. As the trend line in
Figure 9 indicates, the percentage of groundwater
RODs selecting in situ treatment of groundwater
increased from 1986 through 1999. Figure 9
counts all RODs that selected in situ groundwater
treatment regardless of the other remedies selected
in the ROD.
Figure 9. Trend in the Selection of in Situ Croundwater Treatment for
Superfund Remedial Actions (FY1986 - FY 1999)
-------
Section 3: in Situ
Groundwater Treatment
Technologies
In situ technologies for ground-water treatment are
those applications in which the contaminated
groundwater is treated or the contaminant is removed
from the groundwater without extracting, pumping,
or otherwise removing the groundwater from the
aquifer. Implementation of P&T remedies requires
extraction of groundwater from an aquifer, usually
through pumping, and treatment above ground. This
section provides additional information about the
technologies used for in situ groundwater treatment
because they are considered innovative technologies.
Established treatment technologies are those for
which information about cost and performance is
readily available. P&T groundwater remedies are
considered established technologies. Although some
groundwater P&T technologies are innovative or
apply established technologies in an innovative
manner, treatment of groundwater after it has been
pumped to the surface usually involves traditional
water treatment, such as activated carbon adsorption
of organics or precipitation of metals.
Innovative technologies are treatment technologies
whose limited number of applications result in a
lack of data on cost and performance. Innovative
technologies are used for a variety of reasons and
have the potential to provide more cost-effective
and reliable alternatives for remediation.
In some cases, it may be difficult to treat a particular
waste or medium using an established technology.
For example, soil containing a high percentage of
large particle sizes, such as cobbles, boulders, and
large debris, may be difficult to treat using ex situ
thermal desorption because many thermal
desorption units have limitations on the size of
materials that can pass through them. However, in
situ bioremediation may effectively treat the soil
regardless of its particle size distribution. In other
cases, an innovative technology may be less expensive
than an established technology. It may be expensive
to treat soils deep below the ground surface by
incineration because of the amount of excavation
required to reach the soil. However, a thermally
enhanced recovery process may work effectively at
that depth, at a lower cost. Reasons for selecting
innovative technologies can include reduction in the
exposure of workers to contaminated media;
reduction in costs for excavation and materials
handling (in situ technologies); and community
concern about off-site releases of contaminants,
noise, or odor.
The Innovative Remediation Technologies: Field Scale
Demonstration Projects in North America, Second
Edition website contains a report and a searchable
database with information about demonstrations of
innovative remediation treatment technologies in
North America. This website can be accessed at
http://clu-in.org/products/nairt.
As of May 2001, the Federal Remediation
Technologies Roundtable (FRTR) has published 270
case studies that cover a wide range of treatment
technologies that are available for viewing on line
or for downloading from the FRTR website at http:/
lwww.frtr.gov/cost. Of those case studies, some of
which are at Superfund sites, 43 address
groundwater P&T systems, 66 address in situ
groundwater treatment, and 6 address MNA. Table
4 lists the number of FRTR case studies for these
remedy types. The case studies were developed by
EPA, Department of Defense, and Department of
Energy for Superfund and non-Superfund sites.
The case studies present available cost and
performance information for full-scale remediation
efforts and several large-scale demonstration
projects. They provide information about site
background and setting, contaminants and media
Table 4. FRTR Case Studies
for Croundwater P&T,
in Situ Treatment, and MNA
Remedy Type
or Technology
P&T
Number of FRTR
Case Studies
In Situ Groundwater Treatment (total) 66
Bioremediation
Air Sparging
Chemical Treatment
Permeable Reactive Barrier
Dual Phase Extraction
Thermally Enhanced Recovery8
In Situ Flushing8
Phytoremediation
MNA
Total
115
Sources: 11. Data sources are listed in the References and
Data Sources Section on p. 17.
FRTR = Federal Remediation Technologies Roundtable
MNA = Monitored natural attenuation
P&T= Pump and treat
"' No applications of these technologies to groundwater
have been conducted at Superfund sites.
zr
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-------
-------
Figure 11. Contaminants Treated by
in Situ Croundwater Treatment Technologies
for Superfund Remedial Actions (FY1982 - FY1999)
QC -
(0
ง30
12C
5
Si -\*
m 15
3 m
Z
36
20
1
8
5
33 3T
liiJ
1 1
=1, , B.
n
8
Tl
E^.3 2 J
iThJ 1 1 i
, = thS.H 1
1 Air Sparging
CD Bioremediation
Dual-Phase Extraction
Permeable Reactive Barrier
E3 Phytoremediation
IQ] Chemical Treatment
B In-Well Air Stripping
6
1 1 Jb, 1 fl 1
=1, , l,=i,, ..M.r?], , ,l,rn,
Benzene, Other Halogenated Halogenated Polycycjic Other Non- Organic Metals and
Toluene, Nonhalogenated VOCs SVOCs (b) Aromatic Halogenated Pesticides and Metalloids
Ethylbenzene, VOCs (a) Hydrocarbons SVOCs (c) Herbicides
and Xylenes (PAHs)
(BTEX)
Sources3, 4,5, 6. Data sources are listed in the References and Data Sources Section on p. 17.
SVOCs = Semivolatile organic compounds
VOCs = Volatile organic compounds
a. Does not include benzene, toluene, ethylbenzene, andxylene.
b. Does not include halogenated semivolatile pesticides and herbicides.
c. Does not include poly cyclic aromatic hydrocarbons.
Contaminants Addressed
The data collected for this report form the basis
for an analysis of the classes of contaminants treated
by each in situ ground-water treatment technology
type applied at remedial action sites. Figure 11
shows that information, by technology, for 8 major
groups of contaminants.
For this report, compounds are categorized as
VOCs, SVOCs, or PAHs according to the lists
provided in EPA's SW-846 test methods 8010,
8270, and 8310, with the exceptions listed in
the figure notes. Overall, VOCs, including both
BTEX and halogenated VOCs, are the
contaminants most commonly treated in
groundwater using in situ technologies.
Halogenated SVOCs (excluding halogenated
semivolatile pesticides and herbicides) and
metals and metalloids in groundwater are
treated least frequently in situ. The number of
projects in Figure 11 exceeds the total number
of projects in Table 5 (page 14) because some
projects involve more than one type of
contaminant. Such projects, therefore, are
repeated in Figure 11 under each contaminant
type treated by the remedy.
The selection of a treatment technology for a
site often depends on the physical and chemical
properties of contaminants at the site. For
example, VOCs are amenable to treatment by
certain technologies, such as air sparging,
because of their volatility. Metals, which are
not volatile and do not degrade, are not amenable
to these technologies.
The selection of treatment technologies may also
depend on site-specific factors, such as
hydrogeology. For example, air sparging may be
an effective treatment for VOCs at a site with
sandy soil but may not be effective at a site with
tightly-packed clay soil.
As Figure 11 shows, BTEX and halogenated
VOCs are treated most frequently using air
sparging. PAHs and other non-halogenated
SVOCs, which are not as volatile as BTEX and
halogenated VOCs, but can be destroyed through
microbial processes, are treated most frequently
by bioremediation. In some cases, halogenated
VOCs, metals, and metalloids may be difficult to
treat using air sparging, bioremediation, or dual-
phase extraction. However, these contaminants
may undergo chemical reactions with certain
zr
(Q
-------
-------
Section 4: References
and Data Sources
List of Superfund National Priorities List
(NPL) Sites, www.epa.gov/superfund/sites/
query/queryhtmlnplfma.txt September, 2000.
List of NPL Sites That Have Been Deleted.
www.epa.gov/superfund/sites/query/queryhtm/
npldela. txt September, 2000.
Compilation of Record of Decision (ROD)
abstracts, site summaries, and fact sheets for
fiscal years (FY) 1982 through 1997.
www.epa.go v/s up e rfu n d/s i teslq ueryl
advquery.htm January, 2000.
RODs, ROD Amendments, Explanations of
Significant Differences, and ROD abstracts
from FY 1982 through FY 1999.
Contacts With Remedial Project Managers,
FY 1992 through FY 2000.
ROD Annual Reports. EPA Office of
Emergency and Remedial Response (OERR),
1998 through 1992.
Innovative Treatment Technologies: Annual
Status Report (ASR) Tenth Edition (EPA-542-
R-01-004). EPA. Office of Solid Waste and
Emergency Response, clu-in.org/asr February
2001.
8. Personal Communication from Ken Lovelace,
OERR, to Tom Sinski of Tetra Tech EM Inc.,
April, 1998.
9. Contacts with EPA Superfund Removal Branch
Chiefs and On-Scene Coordinators.
10. Groundwater Pump-and-Treat Systems:
Summary of Selected Cost and Performance
Information at Superfund-Financed Sites.
(EPA-542-R-01-0219). EPA. Office of Solid
Waste and Emergency Response, clu-in.org
December 2001.
11. The Federal Remediation Technologies
Roundtable Web Site, www.frtr.gov July, 2001.
12. Use of Monitored Natural Attenuation at
Superfund, RCRA Corrective Action, and
Underground Storage Tank Sites, OSWER
Directive Number 9200.4-17P, U.S. EPA,
April 21, 1999.
13. Innovative Remediation Technologies: Field
Scale Demonstration Projects in North
America, Second Edition, clu-in.org/products/
nairt October, 2001.
14. Federal Remediation Technologies Roundtable
(FRTR). www.frtr.gov/cost May, 2001.
15. Comprehensive Environmental Response,
Compensation, and Liability Information
System (CERCLIS 3).
8
en
-------
APPENDIX A
GROUNDWATER REMEDIES SELECTED IN RECORDS OF
DECISION AT SITES ON THE NATIONAL PRIORITIES LIST
This appendix does not appear in the printed version of Groundwater Remedies
Selected at Superfund Sites. It is available in the online version of this report at
http://clu-in.org/groundwater.
58^
-------
APPENDIX B
IDENTIFICATION OF REMEDY AND RECORD OF DECISION TYPES
FOR SUPERFUND REMEDIAL ACTIONS
-------
B.1 BACKGROUND
This appendix describes the approach used to identify
remedy and ROD types used in the document
Treatment and Monitored Natural Attenuation
Remedies at Superfund Sites. Please note that this
methodology is identical to the one presented in
Appendix F of Treatment Technologies for Site
Cleanup: Annual Status Report (Tenth Edition) (ASR),
with the exception that the hierarchy used to
determine ROD and Site types has been modified to
reflect the focus of this report on groundwater. In
the ASR, source control remedies appeared first in
the hierarchy. In this report, groundwater remedies
appear first in the hierarchy. The methodology
presented here is intended to provide a consistent
and comprehensive approach to identifying remedy
types, and, based on those remedy types, identifying
ROD types. This approach can assist in the transfer
of experience and technology among Superfund sites
by helping remedial project managers (RPMs), On-
Scene Coordinators (OSCs), and other regulatory and
remediation professionals identify sites implementing
similar remedies. Remedy and ROD types are
determined by reviewing the remedies selected in
RODs. Although RODs are written using an overall
format that is consistent, RODs are prepared by
individual RPMs and other staff of the 10 EPA regions.
In addition, the management practices and
techniques used to remediate sites have evolved over
time and continue to evolve. Therefore, the words,
phrases, and descriptions applied to the same or
similar remedies may differ from ROD to ROD. To
facilitate the identification of remedy types, this
appendix includes both descriptive definitions of
remedy types and lists of key words and phrases that
may be used to refer to each remedy type.
The definitions of remedy types provided in this
appendix were based on a review of definitions
and lists of media, remedies, and technologies
provided in the following resources:
The CERCLA Information System
(CERCLIS 3) database
ROD Annual Reports for fiscal years (FY) 1989
through 199 5
The Federal Remediation Technologies
Roundtable (FRTR) Technology Screening Matrix
The ASR remedy type definitions were reviewed
and augmented by a working group of personnel
of the U.S. Environmental Protection Agency
(EPA) Technology Innovation Office (TIO) and
Office of Emergency and Remedial Response
(OERR) who are experienced in site
remediation and ROD preparation and review.
This appendix includes remedy types and
technologies that are not discussed in the ASR.
The ASR focuses on source control treatments and
in situ groundwater treatments. Additional remedy
and technology types are described in this appendix
so that it may be used for purposes beyond the
limited scope of the ASR.
B.2 IDENTIFICATION OF REMEDY AND
ROD TYPES
This appendix describes the methodology used
to classify remedies selected at Superfund
remedial action sites into specific types. Remedy
types were identified by first dividing remedies
into three categories (source control,
groundwater, and no action) based on the media
treated and the type of action. Within each of
these categories, the remedies were then further
divided into the following 12 specific remedy
types, which are also listed in Table B.I with
additional detail:
Grounclwater Remedies:
1. Groundwater pump and treat
2. Groundwater in situ treatment
3. Groundwater containment
4. Groundwater other
5. Groundwater monitored natural attenuation
6. Groundwater extraction
7. Groundwater discharge
Source Control Remedies:
8. Source control treatment
9. Source control containment
10. Source control other
11. Source control monitored natural attenuation
A/o Action Remedies:
12. No action or no further action (NA/NFA)
Each ROD may select multiple remedy types.
When multiple remedy types are selected in a single
ROD, the overall ROD type is the one that appears
first in the list above.
The definitions used to identify each remedy type
are provided in the "Definitions" section below.
When definitions include specific technologies and
those technologies commonly are referred to by
more than one word or phrase, the most commonly
used word or phrase is listed first, followed by
synonyms in parentheses.
Bj)
-------
B. 3 DEFINITIONS USED TO IDENTIFY
REMEDY TYPES
Definitions used to identify remedy types are
presented below. The definitions of treatment
technology and the different types of treatment
technologies (physical, chemical, thermal, and
bioremediation treatment) apply to both source
control and groundwater remedies. Because these
definitions apply to both source control and
groundwater remedies, they are presented once here
rather than being duplicated everywhere they apply.
Treatment Technology - Any unit operation or series
Ok/ /
of unit operations that alters the composition of a
hazardous substance or pollutant or contaminant
through chemical, biological, or physical means so
as to reduce toxicity, mobility, or volume of the
contaminated materials being treated. Treatment
technologies are an alternative to land disposal of
hazardous wastes without treatment. (Federal
Register, volume 55, page 8819, 40 CFR 300.5:
Definitions). Treatment technologies are grouped
into five categories. The definitions for four of the
categories (physical treatment, chemical treatment,
thermal treatment, and biological treatment) are based
on definitions provided in the FRTR Technology
Screening Matrix. The fifth category, other or
unspecified treatment, includes those technologies
that do not fit into the first four categories. The five
treatment technology categories are:
Physical Treatment - Uses the physical properties
of the contaminants or the contaminated medium
to separate or contain the contamination.
Chemical Treatment- Chemically converts hazardous
contaminants to non-hazardous or less toxic
compounds or compounds that are more stable,
less mobile, and/or inert.
Thermal Treatment - Uses heat to: separate
contaminants from contaminated media by
increasing their volatility; destroy contaminants or
contaminated media by burning, decomposing, or
detonating the contaminants or the contaminated
media; or immobilize contaminants by melting the
contaminated media.
Bioremediation Treatment - Stimulates the growth
of microorganisms which metabolize contaminants
or create conditions under which contaminants will
chemically convert to non-hazardous or less toxic
compounds or compounds that are more stable,
less mobile, and/or inert.
Other or Unspecified Treatment - Treatment that
cannot be classified as physical treatment, chemical
treatment, thermal treatment, or bioremediation
treatment.
B.3.1 Grounclwater Remedies
Groundwater Remedy - Management of
groundwater. Groundwater remedies can include
in situ treatment, pump and treat, containment
using vertical engineered barriers, MNA, and other
measures to address groundwater.
Groundwater Media - One or more aquifers
beneath or proximal to a source of contamination
contaminated by migration of a contaminant, such
as leachate, or by other sources.
TABLE B.1
REMEDY TYPES FOR SUPERFUND REMEDIAL ACTION SITES
1. Groundwater Pump and Treat
Extraction of groundwater from an aquifer followed by treatment above ground. Key words used in
RODs to identify groundwater pump and treat remedies are listed below:
Physical Treatment
Aeration (air stripping)
Carbon adsorption
Clarification (sedimentation)
Coagulation
Component separation
Equalization
Evaporation
Filtration
Flocculation
Ion exchange
Oil/water separation
continued on next page
(e-2
-------
1. Groundwater Pump and Treat (continued)
Metals precipitation
Reverse osmosis (microfiltration and ultrafiltration)
Vapor extraction
Chemical Treatment
Chemical reduction
Chemical oxidation (oxidation, cyanide oxidation, and peroxidation)
Neutralization
Ultraviolet (UV) oxidation
Biological Treatment
Biological treatment
Bioreactors
Fixed film
Oxygen enhancement with H2O2
Other or Unspecified Treatment
Pump and treat
Physical/chemical treatment
2. Groundwater In Situ Treatment
Treatment of groundwater without extracting it from the ground. Key words used in RODs to
identify groundwater in situ treatment remedies are listed below:
Physical Treatment
Air sparging
Dual-phase extraction
Free product recovery
in-well air stripping (well aeration and air stripping)
Vapor extraction
Chemical Treatment
Chemical oxidation (oxidation and peroxidation)
Chemical reduction
Chemical treatment
Dechlorination
Permeable reactive barrier (chemical reactive barrier, chemical reactive wall, and passive treatment wall)
Thermal Treatment
Thermally enhanced recovery (conductive heating, CROWฎ, dynamic underground stripping, electrical
resistance heating, hot air injection, hot water or steam flushing and stripping, in-situ thermal
desorption, microwave heating, radio frequency heating, and steam injection)
Bioremediation
Aeration
Biological treatment
Bioremediation
Biosparging
continued on next page
-------
2. Groundwater In Situ Treatment (continued)
Bioslurping
Bioventing
Co-metabolic treatment
Oxygen enhancement with air sparging
Oxygen enhancement with H2O2
Nitrate enhancement
Nutrient injection
Other or Unspecified Treatment
Physical/chemical treatment
Phytoremediation
3. Groundwater Containment
Containment of groundwater, typically through the use of vertical engineered barriers. Key words
used in RODs to identify groundwater containment remedies are listed below:
Vertical Engineered Barrier
Deep soil mixing
Geosynthetic wall
Grout (grout curtain)
High-density polyethylene (HDPE) wall
Impermeable barrier
Sheet pile
Slurry wall
Subsurface vertical engineered barrier (subsurface barrier and subsurface vertical barrier)
Other or Unspecified Containment
Plume containment
4. Groundwater Other
Groundwater remedies that do not fall into the categories Groundwater In Situ Treatment,
Groundwater Pump and Treat, Groundwater Containment, or Groundwater Monitored Natural
Attenuation, including:
institutional Control
Deed restriction
Drilling restriction
Institutional control
Water supply use restriction
Engineering Control
Extended piping
Engineering control
Groundwater Monitoring
Monitoring
Sampling
continued on next page
B-4
-------
4. Groundwater Other (continued)
water Supply Remedies
Alternate water supply (alternate drinking water and bottled water)
Carbon at tap
Seal well (close well)
Treat at use location
Well-head treatment
5. Groundwater MNA
The reliance on natural attenuation processes (within the context of a carefully controlled and monitored
approach to site cleanup) to achieve site-specific remediation objectives within a time frame that is
reasonable, compared with that offered by other, more active methods. The "natural attenuation
processes" that are at work in such a remediation approach include a variety of physical, chemical,
or biological processes that, under favorable conditions, act without human intervention to reduce
the mass, toxicity, mobility, volume, or concentration of contaminants in soil or groundwater. These
in situ processes include biodegradation; dispersion; dilution; sorption; volatilization; radioactive
decay; and chemical or biological stabilization, transformation, or destruction of contaminants (Use
of Monitored Natural Attenuation at Superfund, RCRA Corrective Action, and Underground Storage
Tank Sites, USEPA, Office of Solid Waste and Emergency Response, Directive Number 9200.4-
17P, 1999).
A remedy is considered groundwater MNA if it includes "natural attenuation" or "monitored natural
attenuation" of groundwater.
6. Groundwater Extraction
The process of removing groundwater from beneath the ground surface, including the following
methods of groundwater extraction:
Directional well (horizontal well)
Pumping (vertical well)
Recovery trench (horizontal drain)
7. Groundwater Discharge and Management
A method of discharging or otherwise managing extracted groundwater, including the following
discharge methods and receptors:
Centralized waste treatment facility
Deep well injection
Publicly owned treatment works (POTW)
Recycling
Reuse as drinking water
Reuse as irrigation water
Reuse as process water
Surface drain reinjection
Surface water discharge [National Pollutant Discharge Elimination System (NPDES) discharge]
Vertical well reinjection
B.3.2 Source Control
Source control remedy - any removal, treatment,
containment, or management of any contaminant
source or contaminated medium other than
groundwater.
Source Media - "Source material is defined as
material that includes or contains hazardous
substances, pollutants, or contaminants that act as a
reservoir [either stationary or mobile] for migration
of contamination to the groundwater, to surface water,
-------
to air, [or to other environmental media] or act as a
source for direct exposure. Contaminated
groundwater generally is not considered to be a source
material although non-aqueous phase liquids (NAPLS
[occurring either as residual- or free-phase]) may be
viewed as source materials." (A Guide to Principal
Threat and Low Level Threat Wastes, Superfund
publication 9355.3-02FS, USEPA OEPvR 1991).
Source media include soil, sediment, sludge, debris,
solid-matrix wastes, surface water, non-aqueous phase
liquids (NAPLS), equipment, drums, storage tanks,
leachate, landfill gas, and any other contaminated
media other than groundwater that can act as a
potential source of contamination.
TABLE B.1 (CONTINUED)
8. Source Control Treatment
Any process meant to separate, destroy, or bind contaminants in a source medium. Key words used
in RODs to identify these processes are listed below. More detailed descriptions of most of the
technologies can be found in the ASR or at http://www.frtr.gov.
Physical Treatment
Acid extraction
Air sparging
Air stripping
Carbon adsorption (liquid-phase carbon adsorption)
Clarification
Decontamination
Dewatering
Dual-phase extraction
Electrical separation (electrokinetic separation)
Evaporation
Filtration
Flocculation
Flushing (soil flushing and surfactant flushing)
Ion exchange
Magnetic separation
Oil-water separation
Physical separation (component separation and materials handling)
Reverse osmosis (membrane separation)
Soil flushing (in situ flushing and surfactant flushing)
Soil vapor extraction (vacuum extraction and vapor extraction)
Soil washing
Solidification/stabilization (asphalt batching, immobilization, and microencapsulation)
Solid-phase extraction
Solvent extraction (chemical stripping)
Super-critical fluid extraction
Volatilization (aeration, mechanical soil aeration, and tilling)
Chemical Treatment
Chemical treatment
Chemical oxidation (cyanide oxidation, oxidation, and peroxidation)
Chemical reduction (reduction)
Dehalogenation (dechlorination)
Neutralization
continued on next page
(B-6
-------
8. Source Control Treatment (continued)
Metals precipitation
Ultraviolet (UV) oxidation
Thermal Treatment
Flaring
Gas flaring
High energy corona
Open burning
Open detonation
Plasma high-temperature recovery (fuming gasification and high-temperature metals recovery)
Thermal desorption
Thermal destruction (incineration and pyrolysis)
Thermally enhanced recovery (conductive heating, Contained Recovery of Oily Wastes [CROWฎ],
dynamic underground stripping, electrical resistance heating, hot air injection, in situ thermal
desorption, microwave heating, radio frequency heating, and steam injection)
Thermal treatment
Vitrification (slagging)
Bioremediation
Aeration
Bioremediation
Biological treatment
Bioreactor
Bioventing
Biopile
Composting
Controlled solid phase
Fixed film
Landfarming
Nitrate enhancement
Nutrient injection
Oxidation enhancement with air sparging
Oxidation enhancement with hydrogen peroxide (H2O2)
Slurry-phase bioremediation (bioslurry and activated sludge)
White rot fungus
Other or Unspecified Treatment
Air emission treatment
Gas collection and treatment (off-gas treatment)
Hot gas decontamination
Leachate treatment
Physical-chemical treatment
Phytoremediation
Recycling
Surface water treatment Continued On next page
B-7
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TABLE B.1 (CONTINUED)
9. Source Control Containment
Any process or structure designed to prevent contaminants from migrating from a source media into
groundwater, to surface water, to air, (or to other environmental media) or acting as a source for
direct exposure.
Key words used in RODs to identify source control containment remedies are listed below:
Capping and Cover
Cap
Cover material
Evapotranspiration cover
Revegetation
Bottom Liner
Liner
Clay
Geosynthetic material
Drainage and Erosion Control
Engineering control
Hydraulic control
Impermeable barrier
Subsurface drain
Surface water control (dike, berm, drainage controls, drainage ditch, erosion control, flood
protection, and levee)
Water table adjustment
On-Site Landf illing
On-site consolidation
On-site landfilling
On-site disposal
Off-Site Landfilling
Off-site consolidation
Off-site landfilling
Off-site disposal
Vertical Engineered Barrier
(Must apply to source medium. A vertical subsurface engineered barrier used to control or contain
groundwater is not source control containment.)
Grout (grout curtain)
Impermeable barrier
Sheet piling
Slurry wall
Subsurface barrier
Vertical barrier
Other or Unspecified Containment
Containment (consolidation, disposal, landfilling, and removal)
Encapsulation continued on next page
B-8
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9. Source Control Containment (continued)
Leachate control (leachate collection)
Overpacking
Permanent storage
Repair (pipe repair, sewer repair, and tank repair)
10. Source Control Other
Source control other than treatment or containment.
institutional Control
Access restriction
Deed restriction
Drilling restriction
Fishing restriction
Guard (security)
Institutional control
Land use restriction
Recreational restriction
Swimming restriction
Engineering Control
Engineering control
Fencing
Wetland replacement
Source Monitoring
Monitoring
Sampling
Population Relocation
Population relocation
11. Source Control Monitored Natural Attenuation (MNA)
The reliance on natural attenuation processes (within the context of a carefully controlled and
monitored approach to site cleanup) to achieve site-specific remediation objectives within a time
frame that is reasonable, compared with that offered by other, more active methods. The "natural
attenuation processes" that are at work in such a remediation approach include a variety of
physical, chemical, or biological processes that, under favorable conditions, act without human
intervention to reduce the mass, toxicity, mobility, volume, or concentration of contaminants in
soil or groundwater. These in situ processes include biodegradation; dispersion; dilution; sorption;
volatilization; radioactive decay; and chemical or biological stabilization, transformation, or
destruction of contaminants (Use of Monitored Natural Attenuation at Superfund, RCRA Corrective
Action, and Underground Storage Tank Sites, USEPA, Office of Solid Waste and Emergency
Response, Directive Number 9200.4-17P, 1999).
A remedy is considered source control MNA if it includes "natural attenuation" or "monitored
natural attenuation" for a source (e.g., contaminated soil)
continued on next page
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B.3.3 A/o Action Remedies
TABLE B.1 (CONTINUED)
The designation used for remedies that indicate no action or no further action will be taken. When
determining overall ROD type, the designation is used only for RODs under which NA/NFA is the
only remedy selected. If a ROD selects NA/NFA for only part of a site and another remedy for
another part of a site, the ROD is given the classification corresponding to that selected remedy and
is not given an NA/NFA designation.
BA SPECIAL CASES
This subsection provides a list of some special cases
and descriptions of how remedy and ROD types
should be assigned in those cases:
Decontamination:
' Decontamination of buildings, equipment,
tanks, debris, boulders, rocks, or other objects
is considered source control treatment. For
example, abrasive blasting or scarifying a
concrete pad to remove the contaminated
surface layer of the pad would be considered
source control treatment.
Decontamination of equipment used to clean
up a Superfund site is a normal activity that
occurs at many Superfund sites and is not
considered a remedy. For example, high-
pressure water washing of a front end loader
used to excavate contaminated soil would not
be considered a remedy and would not be
given a remedy type.
Phytoremediation:
Phytoremediation involves the use of
macroscopic plants to destroy, remove,
immobilize, or otherwise treat contaminants.
The process does not use microorganisms.
Processes that use microorganisms are
bioremediation.
The use of plants to control water drainage at
a site is not phytoremediation, but is an
engineering control (source control other or
groundwater other).
Conditional Remedies - If a ROD indicates that a
certain remedy will be implemented under specific
conditions, the ROD is considered to have selected
the conditional remedy. For example, a ROD may
specify that, if soils exceed a certain levels of
contamination, they will be incinerated, but, if they
do not exceed that level, no further action will be
taken. In such a case, the ROD is considered to
have selected incineration and therefore would be
considered a source control treatment ROD.
Vertical Engineered Barriers - Some of the
technologies used for vertical engineered barriers
are also used to control surface water and surface
drainage (for example, slurry walls and sheet piles).
The selected remedy should be analyzed carefully
to determine whether the containment is source
control or groundwater containment.
Solidification/Stabilization - Some of the technologies
used for solidification/stabilization are used for
containment, as well. For example, encapsulation
could mean placing a waste in plastic drums, an
approach that would be classified as source control
containment. Encapsulation of a waste by mixing
it with a monomer and then causing the mixture to
polymerize, resulting in microencapsulation, would
be classified as source control treatment
(solidification/stabilization). In general,
containment involves isolating bulk wastes, while
solidification/stabilization involves incorporating the
waste into a medium so that the leachability of the
contaminants is reduced. The selected remedy
should be analyzed carefully to determine whether
it is a containment or a treatment process.
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