v>EPA
United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102G)
EPA 542-R-99-006
September 1999
clu-in.org
Groundwater Cleanup:
Overview of Operating
Experience at 28 Sites
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EPA 542-R-99-006
September 1999
Groundwater Cleanup:
Overview of Operating Experience
at 28 Sites
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Technology Innovation Office
Washington, DC 20460
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
NOTICE
This document was prepared for the U.S. Environmental Protection Agency (EPA) Technology Innovation Office
(TIO) by Tetra Tech EM Inc. under EPA Contract Number 68-W-99-003. Mention of trade names or commercial
products does not constitute endorsement or recommendation for use. For more information about this project,
please contact: Linda Fiedler, U.S. Environmental Protection Agency, Technology Innovation Office,
401 M Street, S.W. (MC 5102G), Washington, D.C., 20460; telephone: (703) 603-7194; e-mail:
fiedler.linda@epa.gov.
This document may be obtained from EPA's web site at . A limited number of hard
copies of this document are available free of charge by mail from EPA's National Service Center for Environmental
Publications (NSCEP), at or at the following address (please allow four to six weeks for
delivery):
U.S. EPA/National Service Center for Environmental Publications
P.O. Box 42419
Cincinnati, OH 45242
Telephone: (513) 489-8190 or (800) 490-9198
Facsimile: (513) 489-8695
ACKNOWLEDGMENTS
Special acknowledgment is given to the remedial project managers, potentially responsible parties, and vendors involved
at the case study sites for their thoughtful suggestions and support in preparing the individual case studies and in
contributing to this report.
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
EXECUTIVE SUMMARY
This study examined operating experiences at 28 sites across the United States at which
completed or ongoing groundwater cleanup programs are in place. Although not a representative
sample, the sites present a range of the types of cleanups typically performed at sites with
contaminated groundwater. At 21 of the sites, pump-and-treat (P&T) systems were used alone as
the remediation technology; at two of the sites, permeable reactive barriers (PRBs), an in situ
technology, were used alone as the remediation technology. In addition, in situ technologies
were used in conjunction with P&T at five sites, including one site with P&T that was replaced
with a PRB. Individual reports have previously been published for each of the 28 sites by the
Federal Remediation Technology Roundtable and are available at .
Of the 28 case study sites, 24 are Superfund remedial actions, one is a Superfund removal action,
one is a state cleanup, and two are Resource Conservation and Recovery Act (RCRA) corrective
actions. Chlorinated solvents are the type of contaminant most frequently present, found at 21 of
the 28 sites. The sites are located throughout the U.S. and include a range of site types and
hydrogeological conditions. For example, nonaqueous phase liquids (NAPL) were observed or
suspected to be present at 18 of the 28 sites, and hydraulic conductivity varied among the sites by
more than six orders of magnitude.
This report summarizes information about the groundwater remediation systems at the 28 sites,
including: design, operation, and performance of the systems; capital, operating, and unit costs
of the systems; and factors that potentially affect the cost and performance of the systems. Data
from the case studies are compared and contrasted to assist those involved in evaluating and
selecting remedies for groundwater contamination at hazardous waste sites.
Data on performance through late 1997/early 1998 compiled for the report show that total
contaminant removal at the case study sites ranged from seven pounds to more than 510,000
pounds with a median contaminant mass removal of 2,000 pounds. The average annual volume
of groundwater treated ranged from 1.7 million to 550 million gallons (at P&T sites).
Although remediation has been completed at only two of the 28 sites, at the 26 sites with ongoing
remediation, progress has been made toward achieving cleanup goals, including: reducing the
size of a contaminated plume; reducing or eliminating a hot spot within a plume; reducing the
concentrations of contaminants within a plume; removing contaminant mass from a plume; and
achieving containment of a plume.
Capital and operating and maintenance (O&M) costs at the case study sites through late
1997/early 1998 also were compiled for this report. Although P&T and PRB systems may be
designed to accomplish similar remedial goals, the spatial area of groundwater they treat is
generally different; therefore, their costs are presented separately in this report. For the 26 P&T
systems, the approximate median capital cost was $1.9 million and the median average annual
operating cost was $190,000; with median unit costs of $96 of capital cost per average 1,000
gallons of groundwater treated per year and $18 of average annual operating cost per average
1,000 gallons of groundwater treated per year. For the three PRB systems, the approximate
median capital cost was $500,000 and the median average annual operating cost was $85,000;
with median unit costs of $520 of capital cost per average 1,000 gallons of groundwater treated
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
per year and $84 of average annual operating cost per average 1,000 gallons of groundwater
treated per year.
Since the sites summarized in this report were not selected as a representative sample of all
groundwater cleanup sites, the medians, averages, and ranges calculated in this report should not
be used to draw generalizations about cost and performance at other groundwater cleanup sites.
Results of analyses of the case studies showed that the factors affecting cost and performance and
the extent of the effect of those factors varied from site to site. However, based on the
information provided for the 28 case study sites and general observations of groundwater cleanup
as a whole, the following factors have a significant effect on the cost and performance of
groundwater remediation systems.
• Source control factors - Method, timing, and success of source controls to
mitigate contact of NAPLs or other contaminant sources, such as highly
contaminated soil, with groundwater
• Hydrogeologic factors - Aquifer properties that define contaminant transport and
groundwater extraction system design needs, including hydraulic connection of
aquifers that allows for multi-aquifer contamination, aquifer flow parameters,
influences from adjacent surface water bodies on the aquifer system, and
influences of adjacent groundwater production wells on the aquifer system
• Contaminant property factors - Contaminant properties that define the relative
ease that contaminants may be removed from the aquifer, the steps that are
required to treat the extracted groundwater, and the complexity of the contaminant
mixture
• Extent of contamination factors - The magnitude of the contaminated
groundwater plume, including the plume area and depth and the concentrations of
contaminants within the plume
• Remedial goal factors - Regulatory factors that affect the design of a remedial
system and/or the duration that it must be operated, including defining aquifer
restoration or treatment system performance goals and specific system design
requirements, such as disallowing reinjection of treated groundwater or specifying
the treatment technology to be used
• System design and operation factors - The adequacy of a system design to
remediate the site, system downtime, system optimization efforts, the amount and
type of monitoring performed, and the use of in situ technology to replace or
supplement a P&T system
Specific examples of how each of these factors affected the cost and performance of the
groundwater remediation systems at the case study sites are cited within this report.
IV
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
TABLE OF CONTENTS
Section Page
EXECUTIVE SUMMARY iii
LIST OF EXHIBITS vi
ACRONYMS AND ABBREVIATIONS vii
1.0 INTRODUCTION 1-1
2.0 OVERVIEW OF 28 CASE STUDY SITES 2-1
3.0 DESIGN AND OPERATION OF REMEDIAL SYSTEMS
AT 28 CASE STUDY SITES 3-1
3.1 Technology Descriptions 3-1
3.2 Remedial System Designs 3-3
3.3 System Operation 3-6
3.4 System Optimization and Modifications 3-8
4.0 PERFORMANCE OF REMEDIAL SYSTEMS AT 28 CASE STUDY SITES 4-1
4.1 Remedial Goals 4-1
4.2 Progress Toward Goals 4-6
5.0 COST OF REMEDIAL SYSTEMS AT 28 CASE STUDY SITES 5-1
6.0 FACTORS THAT AFFECTED COST AND PERFORMANCE OF REMEDIAL
SYSTEMS AT 28 CASE STUDY SITES 6-1
7.0 REFERENCES 7-1
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
LIST OF EXHIBITS
Exhibit Title
2-1 Summary of 28 Case Study Sites
2-2 Remediation Systems - Years of Operation
2-3 Site Types and Locations
2-4 Categories of Contaminants Treated at 28 Sites
2-5 Specific Contaminants Treated at 28 Sites
2-6 Initial Volume of Contaminated Groundwater Plumes at 24 Sites
2-7 Presence of NAPLs at 28 Sites
2-8 Pertinent Hydrogeological Data at 28 Sites
3-1 Summary of Technologies Used at 28 Sites
3-2 Remedial Technologies Used at 28 Sites
3-3 Pump-and-Treat System Designs at 26 Sites
3-4 Designs of In Situ Treatment Systems at Seven Sites
3-5 Operation of Remedial Systems at 28 Sites
3-6 Types of Optimization and Modification Efforts at 28 Sites
3-7 System Optimization and Modification Efforts Conducted at 28 Sites
4-1 Summary of System Performance for 28 Sites
4-2 Unit Contaminant Mass Removed at 26 Sites
4-3 Summary of Average Contaminant Concentration Reduction at 17 Sites
4-4 System Performance Summary
5-1 Summary of Cost Data for 28 Sites
5-2 Summary of Remedial Cost and Unit Cost Data for 28 Sites
5-3 Average Operating Cost Per Year at 28 Sites
5-4 Capital Cost Per 1,000 Gallons of Groundwater Treated Per Year
5-5 Average Annual Operating Cost Per 1,000 Gallons of Groundwater
Treated Per Year
6-1 Factors Affecting Cost and Performance of Groundwater Remediation
Systems
VI
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
ACRONYMS AND ABBREVIATIONS
AS Air sparging
ACL Alternate concentration limit
BTEX Benzene, toluene, ethylbenzene, and xylene
DCE Dichloroethene
DNAPL Dense nonaqueous phase liquid
DoD U.S. Department of Defense
DOE U.S. Department of Energy
EPA U.S. Environmental Protection Agency
ISB In situ bioremediation
LNAPL Light nonaqueous phase liquid
MCL Maximum contaminant level
NAPL Nonaqueous phase liquid
NPV Net present value
OSWER Office of Solid Waste and Emergency Response
P&T Pump and treat
PAH Polycyclic aromatic hydrocarbon
PCB Polychlorinated biphenyl
POTW Publicly-owned treatment works
PRB Permeable reactive barrier
RCRA Resource Conservation and Recovery Act
ROD Record of Decision
SVOC Semivolatile organic compound
TCE Trichloroethene
TIO Technology Innovation Office
USCG United States Coast Guard
VCB Vertical containment barrier
VOC Volatile organic compound
VII
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
VIM
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
1.0 INTRODUCTION
Groundwater contamination is present at the majority of Superfund and Resource Conservation
and Recovery Act (RCRA) corrective action sites. Groundwater remediation technologies
currently in use to clean up these sites include pump-and-treat (P&T) systems, and in situ
technologies such as bioremediation, permeable reactive barriers, and air sparging. As part of an
effort by the Federal Remediation Technologies Roundtable,1 the U.S. Environmental Protection
Agency (EPA) has prepared 28 case studies of ongoing and completed groundwater remediation
projects. The Roundtable has published these case studies, along with 112 other case studies
about a wide range of technologies, which are available through the Internet at
, or in hard copy through the EPA National Service Center for
Environmental Publications (NSCEP). Case studies are about 10-20 pages in length and contain
information about site background, extent of contamination, technology design and operation,
performance, cost, observations and lessons learned, and points of contact for further
information.
The objective of this report is to provide a summary of information about the 28 groundwater
remediation case studies, including comparing results among sites, to further assist those
involved in evaluating and selecting remedies for groundwater contamination at hazardous waste
sites. The case studies present a range of the type of cleanups typically performed at
groundwater-contaminated sites, and include 21 sites with P&T systems alone, four sites with
P&T systems supplemented with in situ technologies, one site with P&T that was replaced by an
in situ technology, and two systems with only in situ technologies. The majority of the case
studies are ongoing projects, with remediation completed at two of the sites.
The report presents an overview of each of the case study sites (Section 2); describes the design
and operation of the remediation systems, including efforts to optimize the systems (Section 3);
summarizes the performance of each of the systems at the sites, including final results for
completed remediations and progress towards goals for ongoing projects (Section 4); examines
the costs for these systems, including capital, operating, and unit costs (Section 5); and examines
the factors that potentially affect the cost or performance of the remediation systems (Section 6).
References used to prepare this report are listed in Section 7 and are cited in parentheses.
As described in Section 2 of this report, the case study sites were selected in part on the basis of
availability of information. Therefore, it is important to note that the case studies are not
intended to be a representative sample of groundwater remediation projects; rather, they present a
range of the types of systems that are being used at Superfund and RCRA corrective action sites.
Further, this report is not intended to revise or update EPA policy or guidance on how to clean up
sites with contaminated groundwater.
1 The Federal Remediation Technologies Roundtable consists of senior executives from eight agencies
with an interest in site remediation, including the U.S. Army, the U.S. Navy, the U.S. Air Force, the U.S.
Department of Energy (DOE), and EPA. The Roundtable, which was created to build a more collaborative
atmosphere among federal agencies involved in the remediation of hazardous waste sites, has on ongoing effort to
improve the type and availability of cost and performance information for site remediation technologies. This
information is being provided to assist those involved in evaluating and selecting remedies for hazardous waste
cleanups.
1-1
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
1-2
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
2.0 OVERVIEW OF 28 CASE STUDY SITES
The 28 groundwater case study sites
included in this report were selected
from a list of candidate sites that was
developed using information from
previous work by EPA and
recommendations by EPA regional staff.
The following criteria were used in
selecting the specific sites:
>• Sites are located throughout the U.S.
and include a range of site types and
hydrogeological conditions
*• At some sites, groundwater
remediation has been ongoing since
the late 1980s
*• Chlorinated solvents are the most
common contaminant
• Sites at which groundwater cleanup systems had been operated for a relatively
long period of time
• Sites for which aquifer cleanup goals (not only containment goals) had been
established
• Sites for which sufficient cost and performance data were available
Exhibit 2-1 summarizes general information about each of the 28 sites, such as duration and
status of remediation, categories of contaminants targeted for treatment, type of cleanup, project
lead, and highlights of the project. Of the 28 sites, 24 are Superfund remedial actions, one is a
Superfund removal action, one is a state cleanup, and two are Resource Conservation and
Recovery Act (RCRA) corrective actions. Of the 25 Superfund sites, four are EPA led, one is
U.S. Navy led, 11 are potentially responsible party (PRP) led, and nine are state led. The sites
have been grouped by the type of contamination that was targeted for cleanup at each (volatile
organic compounds [VOC], VOCs combined with other contaminants, or metals).
Exhibit 2-2 presents the years of operation at each site. Groundwater remediation at most of the
case study sites is ongoing, with systems operating over periods ranging from two years (USCG
Center andMqffetf) to 11 years (DesMoines and Former Intersil). Cleanup has been completed
at two of the sites (Firestone and Gold Coast) and the remediation systems at three other sites
(French Ltd., Sol Lynn, and Sylvester/Gilson Road) have been shut down for various reasons,
although the cleanups at these sites are not considered complete. At one site (Western
Processing), the goal has been changed from restoration to containment. Nine of the 28 systems
have been operating since the late 1980s. For sites at which systems are ongoing, the information
presented in the report is current as of late 1997 or early 1998.
Exhibit 2-3 shows the type of site and the relative location of each site.
2-1
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 2-1: Summary of 28 Case Study Sites
Site Name, Location,
CERCLIS ID no.
VOCs CONTAMINATION
City Industries SF Site, FL
(City Industries)
CERCLIS #FLD055945653
Des Moines TCE SF Site, IA
(Des Moines)
CERCLIS #IAD98060687933
Former Firestone Facility SF
Site, CA
(Firestone)
CERCLIS #CAD990793887
Former Intersil Inc., CA
(Intersil)
French, Ltd. SF Site, TX
(French, Ltd.)
CERCLIS #TXD980514814
Gold Coast SF Site, FL
(Gold Coast)
CERCLIS #FLD071 307680
JMT Facility RCRA Site (formerly
Black & Decker), NY
(JMT)
Duration/Years
of System
Operation1
4.0
10.5
7.0
10.5
4.0
3.5
10.0
Remediation
Status
Ongoing
Ongoing
Complete
Ongoing
Monitored
Natural
Attenuation
Complete
Ongoing
Contaminant
Categories Targeted
for Treatment
VOCs
VOCs
VOCs
VOCs
VOCs
VOCs
VOCs
Type of
Cleanup2
SF Remedial
SF Remedial
SF Remedial
State Cleanup
SF Remedial
SF Remedial
RCRACA
Lead(s)
PRP
PRP
PRP
PRP
PRP
EPA
Owner/Operator
Site Highlight(s)
Simple hydrogeology with relatively high
hydraulic conductivity; pumping optimization
modeling used
Approximately 5 billion gallons treated to
date to contain and remediate contaminated
groundwater; dense nonaqueous phase liquid
(DNAPL) suspected
Groundwater cleanup completed in seven
years
Used P&T for eight years; replaced that
technology with permeable reactive barrier to
minimize cost of treatment while increasing
effectiveness of treatment, and to return site to
leasable or sellable conditions
Regulatory requirements set as demonstrating,
through modeling, that cleanup goals would
be met at site boundary via monitored natural
attenuation 10 years after P&T is completed
Air sparging used to remediate recalcitrant
area of contamination at the end of the
cleanup, optimization modeling used
Included use of an artificially produced
fracture zone in the bedrock
Notes:
1 Years of system operation as of end of June 1998
2 SF indicates Superfund site; RCRA CA indicates RCRA corrective action site
2-2
Table Continued.
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 2-1: Summary of 28 Case Study Sites
Site Name, Location,
CERCLIS ID no.
Keefe Environmental Services SF
Site, NH (Keefe)
CERCLIS #NHD092059112
Moffett Federal Airfield SF Site,
CA (Moffett)
Mystery Bridge at Highway 20 SF
Site, WY (Mystery Bridge)
CERCLIS #WYD98 1546005
Old Mill SF Site, OH
(Old Mill)
CERCLIS #OHD9805 10200
SCRDI Dixiana SF Site, SC
(SCRDI Dixiana)
CERCLIS #SCD98071 1394
Site A (Confidential SF Site), NY
(Site A)
CERCLIS #Confidential
Sol Lynn/Industrial Transformers
SF Site, TX (Sol Lynn)
CERCLIS #1X0980973327
Solid State Circuits SF Site, MO
(Solid State)
CERCLIS #MOD9808854111
U.S. Aviex SF Site, MI
(U.S. Aviex)
CERCLIS #MID980794556
Duration/Years
of System
Operation1
5.5
2.0
4.5
9.0
6.0
3.0
3.0
5.4
5.0
Remediation
Status
Ongoing
Pilot Scale
Ongoing
Ongoing
Ongoing
Ongoing
Ongoing
Shut Down
Pending
Study
Ongoing
Ongoing
Contaminant
Categories Targeted
for Treatment
VOCs
VOCs
VOCs
VOCs
VOCs
VOCs
VOCs
VOCs
VOCs
Type of
Cleanup2
SF Remedial
SF Remedial
SF Remedial
SF Remedial
SF Remedial
SF Remedial
SF Remedial
SF Remedial
SF Remedial
Lead(s)
State
U.S. Navy
EPA
EPA
EPA '92-'94
PRP '95-present
State
State
State
EPA '93-'96
State '96-
present
Site Highlight(s)
Major modifications to system design based
on optimization study
Permeable reactive barrier successful in
reducing trichloroethene (TCE)
concentrations; increased monitoring required
for technology certification and validation
Monitored natural attenuation used for
remedy of the off-site portion of the plume
System of trenches used to extract shallow
groundwater
Complex hydrogeology; major modifications
made in system by PRP
Remedial system included use of P&T
supplemented with air sparging and in situ
bioremediation
Multiaquifer contamination (three aquifers);
additional contamination identified after
remediation began
Complex hydrogeology (leaky artesian system
in a Karst formation)
Performance modeling used for system
optimization
Notes:
1 Years of system operation as of end of June 1998
2 SF indicates Superfund site; RCRA CA indicates RCRA corrective action site
2-3
Table Continued.
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 2-1: Summary of 28 Case Study Sites
Site Name, Location,
CERCLIS ID no.
Duration/Years
of System
Operation1
Remediation
Status
Contaminant
Categories Targeted
for Treatment
Type of
Cleanup2
Lead(s)
Site Highlight(s)
VOCs COMBINED WITH OTHER CONTAMINANTS
Baird and McGuire SF Site, MA
(Baird and McGuire)
CERCLIS #MADOO 104 1987
King of Prussia Technical
Corporation SF Site, NJ
(King of Prussia)
CERCLIS #NJD980505341
LaSalle Electrical SF Site, IL
(LaSalle)
CERCLIS #SCD980711394
Libby Groundwater SF Site, MT
(Libby)
CERCLIS #MTD980502736
Mid-South Wood Products SF
Site, AR (MSWP)
CERCLIS #ARD092916188
Solvent Recovery Services of New
England, Inc. SF Site, CT
(Solvent Recovery Service)
CERCLIS #CTD009717604
Sylvester/Gilson Road SF Site, NH
(Sylvester/Gilson Road)
CERCLIS #NHD099363541
5.5
3.5
5.5
7.0
9.0
3.0
9.5
Ongoing
Ongoing
Ongoing
Ongoing
Ongoing
Ongoing
Shut Down
Pending
Explanation
of Significant
Difference
(ESD)
VOCs, semivolatile
organic compounds
(SVOCs), pesticides,
metals
VOCs, metals
VOCs,
polychlorinated
biphenyls (PCBs)
VOCs, SVOCs
VOCs, SVOCs
VOCs, metals
VOCs, pesticides,
metals
SF Remedial
SF Remedial
SF Remedial
SF Remedial
SF Remedial
Removal
SF Remedial
EPA
PRP
State
PRP
PRP
PRP
State
Complex mixture of contaminants requiring
extensive treatment train
Complex mixture of contaminants requiring
extensive treatment train
Relatively low groundwater flow; DNAPLs
present
Light nonaqueous phase liquids (LNAPLs)
and DNAPLs perpetuate elevated levels of
contaminants in groundwater
System optimization performed after eight
years of operation; contamination reduced to
one localized area of concern
Complex mixture of contaminants having
various properties led to extensive treatment
train; DNAPLs present
Modifications of the system were costly;
system shut down since 1996, pending an
ESD to raise the alternate concentration limit
(ACL) for 1,1-dichloroethane to greater than
method detection limit
Notes:
1 Years of system operation as of end of June 1998
2 SF indicates Superfund site; RCRA CA indicates RCRA corrective action site
2-4
Table Continued.
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 2-1: Summary of 28 Case Study Sites
Site Name, Location,
CERCLIS ID no.
USCG Support Center, NC
(USCG Center)
Western Processing SF Site, WA
(Western Processing)
CERCLIS #WAD009487514
Duration/Years
of System
Operation1
2.0
10.0
Remediation
Status
Ongoing
Ongoing
Contaminant
Categories Targeted
for Treatment
VOCs, metals
VOCs, metals
Type of
Cleanup2
RCRACA
SF Remedial
Lead(s)
Owner/Operator
PRP
Site ffighlight(s)
Use of PRB to treat groundwater
contaminated with TCE and hexavalent
chromium; extensive sampling conducted to
evaluate
Goals for off-site plume met; on-site system
modified to provide containment of on-site
contamination rather than site restoration;
NAPL observed and suspected in various
areas of the site
METALS CONTAMINATION
Odessa Chromium I SF Site, TX
(Odessa I)
CERCLIS #1X0980867279
Odessa Chromium IIS SF Site, TX
(Odessa IIS)
CERCLIS #1X0980697114
United Chrome SF Site, OR
(United Chrome)
CERCLIS #ORD009043001
4.5
4.5
10.0
Ongoing
Ongoing
Ongoing
metals
metals
metals
SF Remedial
SF Remedial
SF Remedial
State
State
PRP
Low groundwater production; electrochemical
treatment for chromium required by Record of
Decision (ROD)
Relatively low groundwater production;
multiaquifer contamination; electrochemical
treatment for chromium required by ROD
Contaminant concentrations reduced to the
point at which extracted groundwater can be
discharged to the publicly-owned treatment
works (POTW) without on-site treatment;
major modifications made in extraction
system
Notes:
1 Years of system operation as of end of June 1998
2 SF indicates Superfund site; RCRA CA indicates RCRA corrective action site
2-5
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 2-2: Remediation Systems - Years of Operation
Site Name, Location
Former Firestone Facilty SF Site, CA
Sylvester/Gibon Road SF Site, NH
Former Intersil Inc., CA
Des Moines ICE SF Site, IA
JMT Facility RCRA Site (formerly Black & Decker), NY
United Chrome SF Site, OR
Western Processing SF Site, WA
Old Mill SF Site, OH
Mid-South Wood Products SF Site, AR
Gold Coast SF Site, FL
Libby Groundwater SF Site, MT
French, Ltd. SF Site, TX
LaSalte Electrical SFSite, IL
Sold State Circuits SF Site, MO
Baird and McGuire SFSite, MA
Keefe Environmental Services SF Site, NH
U.S.Aviex SFSite, Ml
Sol Lynn/Industrial Transformers SF Site, TX
Odessa Chromium 1 SF Site, TX
Mystery Bridge at Highway 20 SF Site, WY
City Industries SF Site, FL
King of Prussia Technical Corporation SF Site, NJ
1986
Solvent Recovery Services of New England, Inc. SF Site, CT
Site A (Confidential) SF Site, NY
Moffett Federal Airfield SF Site, CA
USCG Support Center, NC
1987 I 1988
1989
1990
1991
1992
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10.5
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5.5
5.5
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Notes:
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Indicates ongoing cleanups.
Groundwater cleanup is complete.
Sylvester/Gilson Road system was shut down pending an Explanation of Significant Difference.
French Limited cleanup continues by natural attenuation since 12/95. Cleanup is not complete.
Sol Lynn system was shut down for maintenance and upgrade in 10/96. Cleanup is not complete.
2-6
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 2-3: Site Types and Locations
Western Processing SF Site
(waste processing) , -,,
Kent,WA [ ft
Libby Groundwater SF Site
lumber mil/wood preserving)
,MT
Moffett Federal
Airfield SF Site
(service and support
for Navy aircraft)
Mountain View, CA
Former Firestone
Facility SF Site
(manufacturing)
Sainas, CA
Old Mil SF Site
(illegal waste disposal)
Rock Creek, OH
JMT Facilty RCRA Site (formerly
Black & Decker)
(appiance manufacturing)
Brockport, NY
Mystery Bridge at Highway 20 SF
Site
(oil & gas production equipment)
EvansviHe, WY
U.S.AviexSFSite
(automotive fluids
manufacturing)
Miles, Ml
Des Moines TCE SF Site
(metal wheel and brake
manufacturing)
Des Moines, IA
A 1
LaSalje Electrical SF Site
(electrical equipment
manufacturing)
LaSalle.lL
Solid State Circuits SF Site
(circuit board manufacturing)
Republic, MO
Former Intersil Inc.,
(semiconductor manufacturing)
Sunnyvale, CA
A
SCRDI Dixiana SF Site
(waste storage)
Cayce, SC
Sol Lynn/Industrial
Transformers SF Site
(scrap metal and transformer
reclamation)
French, Ltd. SF Site
(industrial waste disposal)
Crosby, TX
Sylvester/Gilson Road SF Site
(ilegal waste disposal)
Nashua, NH i
Keefe Environmental
Services SF Site
(spent solvent
reclamation)
Epping, NH
Baird and McGuire SF Site
(chemical mixing
and batching)
Holbrook, MA
Solvent Recovery Services of
New England, Inc. SF Site
(solvents recovery)
Southington, CT
Site A (Confidential) SF Site
(petroleum bulking, chemical
mixing)
Long Island, NY
King of Prussia Technical
Corporation SF Site
(waste disposal and recycling)
Winslow, NJ
USCG Support Center
(electroplating operations)
Elizabeth City, NC
Odessa Chromium I SF Site
(chrome plating)
Odessa, TX
Odessa Chromium IIS SF Site
(chrome plating)
Odessa, TX
City Industries SF Site
(hazardous waste disposal)
Orlando, FL
.Gold Coast SF Site
(spent oil and solvent reclamation)
Miami, FL
2-7
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 2-4 summarizes the types of contaminants treated at the 28 sites. The contaminants fall
into the following categories. Multiple contaminant category groups have been targeted for
treatment at some sites.
• Volatile organic compounds (VOCs)
* Chlorinated VOCs
*• Benzene, toluene, ethylbenzene, and xylene (BTEX)
»> Other VOCs
• Semivolatile organic compounds (SVOCs)
>• Pesticides
*• Polycyclic aromatic hydrocarbons (PAHs)
>• Polychlorinated biphenyls (PCBs)
Other SVOCs
• Metals
Chlorinated VOCs were the type of contaminant most frequently present, found at 21 of the 28
sites.
Exhibit 2-5 summarizes information about the specific contaminants addressed at the sites. Only
contaminants that were treated at more than one site are included in this exhibit. Six of the 10
most common contaminants treated were chlorinated VOCs, with trichloroethene (TCE), treated
at 18 sites, the most common. Benzene was the most commonly treated nonchlorinated VOC (at
five sites). Chromium was the most common metal, treated at seven of the sites.
Exhibit 2-6 shows the volume of the contaminated groundwater plume at each site. For most of
the sites, the extent of contamination was quantified by the volume of contaminated groundwater.
Plume volume presented for these sites generally represents one pore volume of the contaminated
plume prior to commencing groundwater cleanup activities at the site. The volume was
calculated by the site contractors or during the preparation of the cost and performance reports by
combining isoconcentration data for groundwater contaminants with reported or typical
hydrogeological data. The volume of contaminated groundwater at the sites ranged from 930,000
gallons (Intersil) to 5.6 billion gallons (Moffetf). The average volume of the contaminated plume
was 440 million gallons, and the median volume was 29 million gallons.
2-8
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 2-4: Categories of Contaminants Treated at 28 Sites
Chlorinated VOCs
BTEX
Other VOCs
Pesticides
PAHs
PCBs
Other SVOCs
Metals
10 15 20
Number of Case Study Sites
25
Exhibit 2-5: Specific Contaminants Treated at 28 Sites
20
18 -
8! 16-
(0 t/> H A
Q 0) 14 ~
Silil
4 -
2 -
18"
15
9 9
7 7
2-9
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 2-6: Initial Volume of Contaminated Groundwater Plumes at 24 Sites1
*
*
1*
•
o*6
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D
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 2-7 summarizes information on the observed and suspected presence of nonaqueous
phase liquid (NAPL) at the sites either as light nonaqueous phase liquid (LNAPL), which
generally floats on the water table, or dense nonaqueous phase liquid (DNAPL), which typically
sinks through permeable media (including saturated materials) to an impermeable barrier. Of the
28 sites: NAPLs were observed or suspected to be present at 18; DNAPL only was observed or
suspected at 12 sites; LNAPL only was observed or suspected at three sites; and both DNAPL
and LNAPL was observed or suspected at three sites. As described in Estimating Potential for
Occurrence of DNAPL at Superfund Sites [6], NAPL can be "suspected" at a site if its
components are present in groundwater at greater than one percent of either their pure-phase
solubility or effective solubility. For the case study sites, NAPL was considered "suspected" if at
lease one component was present at greater than one percent of its pure-phase solubility.
Exhibit 2-7: Presence of NAPLs at 28 Sites
Site Name and Location
Baird and McGuire, MA
City Industries, FL
Des Moines, IA
Firestone, CA
French, Ltd., TX
Gold Coast, FL
Intersil, CA
JMT,NY
Keefe, NH
King of Prussia, NJ
LaSalle, IL
Libby, MT
Moffett, CA
MSWP, AR
Mystery Bridge, WY
Odessa I, TX
Odessa IIS, TX
Old Mill, OH
SCRDI Dixiana, SC
Site A, NY
Sol Lynn, TX
Solid State, MO
Solvent Recovery Service, CT
Sylvester/Gilson Road, NH
U.S. Aviex,MI
United Chrome, OR
USCG Center, NC
Western Processing, WA
Number ot Sites
NAPL Observed or Suspected
DNAPL
Observed
•
•
•
•
•
•
•
7
Suspected1
•
•
•
•
•
•
•
•
8
LNAPL
Observed
•
•
•
•
•
•
6
Suspected1
0
Note:
Suspected NAPL was identified in the case study reports when contaminants were present at more
than one percent of their either their pure-phase solubility or effective solubility.
2-11
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 2-8 presents information about the hydrogeologic conditions at the 28 sites. The average
hydraulic conductivity of the contaminated water-bearing layer(s) at the sites varied by more than
six orders of magnitude (0.023 feet per day (ft/day) to 1,200 ft/day). At more than half of the
sites, contamination was present in multiple water-bearing layers or aquifers. Seven of the sites
exhibited vertical groundwater flow between aquifers, 13 sites were influenced by adjacent
bodies of surface water, and eight sites were influenced by the presence of production wells (for
example, municipal). Reported depths to the top of contaminated aquifers ranged from zero (at
ground surface) to 45 ft below ground surface (bgs). Additional detail on the hydrogeologic
conditions, such as aquifer type, lithology, and degree of heterogeneity at the sites can be found
in the case studies.
Exhibit 2-8: Pertinent Hydrogeological Data at 28 Sites
Site Name and Location
Baird and McGuire, MA
City Industries, FL
Des Moines, IA
Firestone, CA
French, Ltd., TX
Gold Coast, FL
Intersil, CA
JMT,NY
Keefe, NH
King Of Prussia, NJ
LaSalle, IL
Libby, MT
Moffett, CA
MSWP, AR
Mystery Bridge, WY
Odessa I, TX
Odessa IIS, TX
Old Mill, OH
SCRDI Dixiana, SC
Site A, NY
Sol Lynn, TX
Solid State, MO
Solvent Recovery
Service, CT
Sylvester/Gilson Road, NH
U.S. Aviex, MI
United Chrome, OR
USCG Center, NC
Western Processing, WA
Hydraulic
Conductivity
Range (ft/day)
3-45
6.39
535
100-1200
0.28-2.8
40
370
0.65-0.93
42.5
Variable
0.22
100-1000
0.3-400
Variable
340
1.6-5.1
1.6-5.1
0.22-1.25
10
53.5
0.14-25.5
0.023-1.62
0.023-300
30-50
9.1-45.4
0.5-60
11.3-25.5
1-100
Multiple
Aquifer
Contamination
Y
Y
N
Y
Y
Y
N
Y
N
N
N
Y
Y
Y
N
Y
Y
N
Y
N
Y
Y
Y
Y
N
Y
N
Y
Vertical
GW
Flow
N
N
N
N
N
N
Y
N
N
N
Y
N
Y
N
N
N
N
N
N
Y
N
Y
N
Y
N
Y
N
N
Surface
Water
Influence
Y
N
Y
N
Y
Y
N
N
N
Y
N
Y
N
N
N
N
N
Y
N
Y
N
Y
Y
Y
N
N
Y
Y
Production
Wells in
Area
N
N
Y
Y
N
Y
N
N
N
N
N
Y
N
N
N
Y
Y
N
N
N
N
Y
N
N
Y
N
N
N
Depth to
Contaminated
Aquifer (ft bgs)
10-15
NR
10-25
NR
10-12
5.0
NR
10.0
NR
15.0
3-5
10-20
5.0
NR
14-42
30-45
30-45
5.0
14.0
15-18
20-25
NR
NR
NR
20.0
0-10
6.0
5-10
Notes:
GW = Groundwater
NR = Not recorded in case studies
2-12
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
3.0 DESIGN AND OPERATION OF REMEDIAL SYSTEMS AT 28 CASE
STUDY SITES
Most of the sites used P&T alone;
five of the sites used P&T in
combination with in situ technologies
Eighteen of the P&T systems at the
sites used air stripping as
aboveground treatment; carbon
adsorption, metal removal, and
biological treatment also were used to
a lesser extent
The volume of groundwater treated
per year of operation at the P&T sites
ranged from 1.7 million to 554
million gallons
Optimization and modification efforts
have been made to some extent at all
of the sites
The design of the groundwater remediation
systems at the 28 sites include: pump-and-treat
(P&T) systems used alone as the remediation
technology at 21 sites; in situ technologies
(permeable reactive barriers [PRB] in these
cases) used alone as the remediation technology
at two sites, and in situ technologies, such as in
situ bioremediation, air sparging, or PRBs, used
in conjunction with or to replace P&T systems at
five sites. Source controls were identified at 23
of the sites. Vertical containment barriers (VCB)
were used at five of the sites to provide hydraulic
control of contaminant plumes.
The technologies used at the 28 case study sites
are described briefly below, followed by a
detailed summary of the remedial system designs implemented at the case study sites.
3.1 Technology Descriptions
Pump-and-Treat
P&T involves extracting contaminated groundwater through recovery wells or trenches and
treating the extracted groundwater by ex situ (aboveground) processes, such as air stripping,
carbon adsorption, biological reactors, or chemical precipitation. Variables in the design of a
typical P&T system include:
• The number and production rate of groundwater extraction points (determined by
such factors as the extent of contamination and the productivity of the
contaminated aquifer)
• The ex situ treatment processes employed (determined by such factors as system
throughput and the contaminants that require remediation)
• The discharge location for treatment plant effluent (determined by such factors as
location of the site and regulatory requirements)
Additional information about the fundamentals of P&T technology can be found in Design
Guidelines for Conventional Pump-and-Treat Systems [1].
3-1
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Air Sparging
Air sparging (AS) involves injecting a gas (usually air or oxygen) under pressure into the
saturated zone to volatilize contaminants in groundwater. Volatilized vapors migrate into the
vadose zone where they are extracted by vacuum, generally by a soil vapor extraction system.
AS also is used to supplement P&T systems. For example, AS may be added to remediate
specific portions of a contaminated plume that are not treated effectively by P&T alone or to
accelerate cleanups. For the purpose of this report, the use of air to promote biodegradation
(sometimes referred to as "biosparging") in saturated and unsaturated soils by increasing
subsurface concentrations of oxygen is referred to as in situ bioremediation.
Permeable Reactive Barriers
A PRB, or treatment wall, consists of an in-ground trench that is backfilled with a reactive
medium. The selection of the reactive medium is based on the targeted contaminants and the
hydrogeologic setting of the site. Zero-valent iron is the most common medium used in PRBs to
date. Examples of other reactive media include, microorganisms, zeolite, activated carbon, peat,
phosphate, bentonite, limestone, and amorphous ferric oxide. The treatment processes that occur
within the tremch are degradation, sorption, or precipitation of the contaminant. PRB systems
may be configured as "funnel and gate" designs; in such configurations groundwater flow is
routed by two or more impermeable walls through a permeable reactive zone.
PRBs may or may not be similar to P&T systems in both purpose and function. Like a P&T
system, PRBs may be used to treat contaminated groundwater at the boundary of a site, or to
restore the groundwater throughout a site. However, the volume of groundwater treated by a
PRB at a site is typically much lower than it would be for a P&T system at the same site because
PRBs treat only the groundwater that passes through the barrier, while P&T systems actively
extract groundwater from an aquifer, usually at multiple locations throughout the plume.
In Situ Bioremediation
In situ bioremediation (ISB) involves microbial degradation of organic constituents through
aerobic or anaerobic processes. In situ bioremediation includes processes by which nutrients
(such as nitrogen and phosphorus), electron donors (such as methane for aerobic processes or
methanol for anaerobic processes), or electron acceptors (such as oxygen for aerobic processes or
ferric iron for anaerobic processes) are added to the groundwater to enhance the natural
biodegradation processes. The addition of oxygen by biosparging is an example of such a
process.
Source Controls
Source controls include such activities as excavation of soil at hot spots, in situ treatment of soil
(for example, by soil vapor extraction), and installation of VCBs for control of NAPLs. Source
controls are implemented to remove source materials or to isolate them from contact with
groundwater.
3-2
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Vertical Containment Barriers for Hydraulic Control
VCBs, such as slurry or sheet pile walls, also are used to hinder the migration of contaminated
groundwater. VCBs are used in conjunction with groundwater extraction wells in an effort to
gain hydraulic control over a contaminated groundwater plume.
3.2 Remedial System Designs
Exhibit 3-1 lists the remedial technologies used at the 28 subject sites. At most of the sites (26 of
28), P&T systems were used for groundwater remediation. At five of the P&T sites, in situ
technologies were incorporated into the P&T approach. AS was incorporated at two sites, ISB at
three sites, and PRBs at one site. At two sites, PRBs were used alone as the remedial technology.
Source controls were used at most (24) of the sites, and VCBs were used for hydraulic control
five sites.
Exhibit 3-1: Summary of Technologies Used at 28 Sites
Technology
Total P&T Technologies
Total In Situ Technologies
P&T Only
P&T with In Situ Technology or Technologies
Air Sparging
In Situ Bioremediation
Air Sparging and In Situ Bioremediation
Permeable Reactive Barriers (replaced P&T)
In Situ Technology Only
Air Sparging
In Situ Bioremediation
Permeable Reactive Barriers
Vertical Containment Barriers for Hydraulic Control
Source Controls
Number of
Sites
26
7
21
5
1
2
1
1
2
0
0
2
5
24
Exhibit 3-2 identifies the specific remedial technology or technologies used at each of the sites.
Extracted groundwater at the sites was treated using treatment systems varying from an
individual ex situ technology to a complex series of different technologies. The ex situ treatment
technologies included:
Air stripping
Carbon adsorption
Filtration
Electrochemical removal of
metals
Oil/water separation
Chemical or ultraviolet
oxidation
Biological degradation
Neutralization
Equalization
3-3
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Vapor-phase treatment of off-gases from the ex situ technologies was employed at eight of the
sites. At those sites, vapor-phase incineration, carbon adsorption, filtration, or thermal oxidation
were used either individually or in series.
Exhibit 3-2: Remedial Technologies Used at 28 Sites
Site Name and
Location
Baird and McGuire,
MA
City Industries, FL
Des Moines, IA
Firestone, CA
French, Ltd., TX
Gold Coast, FL
Intersil, CA
JMT,NY
Keefe, NH
King of Prussia, NJ
LaSalle, IL
Libby, MT
Moffett, CA
MSWP, AR
Mystery Bridge, WY
Odessa I, TX
Odessa IIS, TX
Old Mill, OH
SCRDI Dixiana, SC
Site A, NY
Sol Lynn, TX
Solid State, MO
Solvent Recovery
Service, CT
Sylvester/Gilson Road,
NH
U.S. Aviex,MI
United Chrome, OR
USCG Center, NC
Western Processing,
WA
Total Sites
Remediation Technology
P&T (with ex situ treatment)
VI
•
•
•
•
4
i/i
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
18
§
•
•
•
•
•
•
•
•
•
•
10
[METAL
•
•
•
•
•
•
•
•
•
•
•
11
Q
«
•
•
•
3
Other
Filtration
Equalization
Filtration
Neutralization;
addition of nutrients
and oxygen
Equalization;
clarification; filtration
Filtration
Filtration
Filtration
Settling; filtration;
addition of nutrients;
pH adjustment of
effluent
pH adjustment
Oxidation; filtration;
pH adjustment
Oxidation; filtration
VI
•<
•
•
2
CO
CO
HH
•
•
•
3
CO
£
•
•
•
3
M
g
•
•
•
•
•
5
Notes:
OWS = Oil/water separation AS
STRIP = Air stripping ISB
GAC = Granular activated carbon adsorption PRB =
METAL = Physical or chemical removal of metal VCB =
BIO = Biological treatment NA
Source Control(s)
Implemented
Concurrent excavation
Prior excavation
Prior excavation
Prior excavation
Prior in situ
bioremediation of soil and
sludges
NA
Prior excavation
Prior excavation
Prior excavation
Prior soil washing
Prior excavation
Prior excavation
NA
Prior excavation
Prior excavation/S VE
NA
Prior excavation
Prior excavation
Prior excavation
Prior excavation
Prior excavation
Prior excavation
Prior excavation
Prior and concurrent
capping/slurry wall/
excavation/S VE
NA
Prior excavation
Prior excavation
NA
Air sparging
In Situ bioremediation
Permeable reactive barrier
Vertical containment barrier
Not Available
3-4
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 3-3 identifies the extraction system design for each of the P&T sites. Groundwater
extraction designs at the 26 P&T sites varied in magnitude from one production well (JMT) to
several wells combined with trenches (MSWP and Old Mill) and to 210 vacuum wellpoints
(Western Processing). Pumping rates for the P&T systems ranged from 3 gallons per minute
(OldMill) to more than 1,000 gallons per minute (DesMoines).
Exhibit 3-3: Pump-and-Treat System Designs at 26 Sites
Site Name, Location
Baird and McGuire, MA
City Industries, FL
Des Moines, IA
Firestone, CA
French, Ltd., TX
Gold Coast, FL
Intersil, CA
JMT, NY
Keefe, NH
King of Prussia, NJ
LaSalle, IL
Libby, MT
MSWP, AR
Mystery Bridge, WY
Odessa I, TX
Odessa IIS, TX
Old Mill, OH
SCRDI Dixiana, SC
Site A, NY
Sol Lynn, TX
Solid State, MO
Solvent Recovery Service,
CT
Sylvester/Gilson Road, NH
U.S. Aviex,MI
United Chrome, OR
Western Processing, WA
Minimum
Maximum
Average
Median
Number of Wells
Extract
6
13
7
25
109
5
3
1
5
11
0
5
15
3
6
10
3
15
5
12
7
12
14
5
30
210
0
210
21
7
Inject
0
0
0
0
59
3
0
0
0
0
0
11
0
0
6
9
0
0
0
14
0
0
0
0
0
0
0
59
4
0
Number of
Trenches
Extract
0
0
0
0
0
0
0
0
1
0
3
0
8
0
0
0
5
1
0
0
0
0
0
0
0
0
0
8
0.7
0
Inject
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
0
7
0
0
1
0
7
0.4
0
Pumping
Rate
Average
gpm
60
105
1041
484
189
44
8
11.2
23.4
200
17
6.6
24
103
60
58.5
3.1
40
18
8
34
20
265
220
242
230
3.1
1041
140
51
Number Of
Wells/ Trenches
(by Location)
On-site
6
13
7
15
NR
5
4
1
1
4
3
5
10
3
NR
NR
NR
8
5
NR
4
6
14
1
NR
210
1
210
16
5
Off-
site
0
0
0
10
NR
0
0
0
5
7
0
0
5
0
NR
NR
NR
12
0
NR
3
6
0
4
NR
3
0
12
3
0
Treated
Groundwater
Discharge
E
,1
<2.E
•
•
•
•
NR
•
•
•
•
•
•
•
•
•
Surface
Water
•
•
NR
•
•
•
•
•
•
•
•
•
2
•
NR
•
•
Notes:
NR = Not reported
3-5
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 3-3 shows that treated groundwater was reinjected into the aquifer (11 sites), discharged
to an adjacent surface water by a permitted outfall (10 sites), discharged to a publicly owned
treatment works (POTW) (2 sites), or discharged using a combination of these methods (2 sites).
Exhibit 3-4 describes the remedial systems at the seven case study sites where in situ
technologies were used.
Exhibit 3-4: Designs of In Situ Treatment Systems at Seven Sites
Site Name
and
Location
French,
Ltd., TX
Gold Coast,
FL
Intersil, CA
Libby, MT
Moffett,
CA
Site A, NY
USCG
Center, NC
In Situ
Technology(ies)
Used
ISB
AS
PRB
ISB
PRB
AS and ISB
PRB
Design of In Situ Treatment System
P&T system augmented with ISB. ISB system consisted of the reinjection of treated
groundwater into the contaminated aquifer. The treated groundwater was oxygenated
and amended with nitrogen and phosphorus before reinjection.
AS used only at end of cleanup to mitigate a small area of localized contamination.
Original design was a P&T system, which was turned off in 1995 after PRB was
installed. PRB system consisted of two parallel slurry walls 300 and 235 feet long and
1 3 feet deep used to funnel groundwater through a 40-foot- wide, 4-foot-thick permeable
wall of granular iron.
P&T system complemented with ISB. ISB system consisted of the reinjection of treated
groundwater into the contaminated aquifer. Treated groundwater was aerated and
amended with nitrogen and phosphorus in the treatment plant after removal of NAPL
and before it flowed through a series of fixed-film bioreactors.
PRB consisted of an impermeable "funnel" composed of two 20-foot-long sheet pile
walls. Reactive zone consisted of 6-foot- thick, 10-foot- wide, and 18-foot-high
(beginning 5 feet bgs) zone of granular iron. The reactive zone was located between two
zones of pea gravel, each two feet thick.
P&T system in conjunction with AS and ISB. AS system consisted of air injection
through 44 sparging wells at points approximately 10 feet below the water table, with
vapor collection through 20 soil vapor extraction wells (16 vertical and 4 horizontal).
ISB system consisted of the reinjection of treated groundwater into the contaminated
aquifer. The treated groundwater was amended with nitrogen and phosphorus before it
was discharged to the reinjection trench.
PRB consisted of a 2-foot-thick and 1 52-foot-long zone of approximately 450 tons of
granular zero-valent iron keyed into an underlying low conductivity layer at
approximately 22 feet bgs.
3.3 System Operation
Exhibit 3-5 presents data available on the operation of the remedial systems, including the
volume of groundwater treated and the percent of time the systems were operational. The
volume of groundwater treated per year of operation for the P&T systems ranged from 1.7
million gallons (OldMill) to 554 million gallons (DesMoines). Estimated throughput per year
for the PRB sites ranged from 200,000 gallons (Moffett) to 2.6 million gallons (USCG Center).
3-6
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 3-5: Operation of Remedial Systems at 28 Sites
Site Name and Location
Baird and McGuire, MA
City Industries, FL
Des Moines, IA
Firestone, CA
French, Ltd., TX
Gold Coast, FL
Intersil (P&T), CA3
Intersil (PRB), CA23
JMT,NY
Keefe, NH
King of Prussia, NJ
LaSalle, IL
Libby, MT
Moffett (PRB), CA2
MSWP, AR
Mystery Bridge, WY
Odessa I, TX
Odessa IIS, TX
Old Mill, OH
SCRDI Dixiana, SC
Site A, NY
Sol Lynn, TX
Solid State, MO
Solvent Recovery Service, CT
Sylvester/Gilson Road, NH
U.S. Aviex, MI
United Chrome, OR
USCG Center (PRB), NC2
Western Processing, WA
Minimum
Maximum
Average
Median
Volume of GW Extracted
(million gallons)1
Total
80
151.7
4900
1800
306
80
36
2
50.1
46
151.5
23
15.1
0.284
100.6
192.8
125
121
13
20.6
8.4
13
257
32.5
1200
329
62
2.6
974
0.284
4900
382.5
80
Per Year
21
50
554
266
76
22
5.0
1.1
5.2
11
57
5.2
2.9
0.2
12
54
30
30
1.7
4.5
6.7
4.3
62
11
126
96
7.2
2.6
119
0.2
554
57
12
Percent of Time
Operational (%)
93
90
95
97
90
95
98
100
90
97
76
75
89
100
NR
100
95
95
99
89
75
69
95
100
88
95
99
100
97
69
100
92
95
Notes:
1 At most of the sites, groundwater cleanups are in progress; therefore the values shown represent a portion
of the total volume treated. Data presented here generally are cumulative as of late 1997 or early 1998.
2 The volume of groundwater for PRB sites is equal to the volume of groundwater treated through the wall
at the site.
3 At the Intersil site, groundwater cleanup began with a P&T system; later a PRB was used. The two
phases were treated above as separate sites.
NR = Not reported
3-7
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
The percent of time that the remedial systems were operational at the sites ranged from 69 to 100
percent. Downtime reportedly was required for routine maintenance (such as changing carbon,
cleaning air stripper media, and backwashing filters) and issues specific to particular sites, including:
• Iron corrosion and clogging of extraction wells (Baird andMcGuire, Des Moines, Odessa I,
Odessa IIS, Mystery Bridge, and Solvent Recovery Services)
• Freezing or fouling of air stripper media (Solid State and City Industries)
• System modifications (Keefe, Solid State, Site A, MSWP, and Sylvester/Gilson Road)
• Equipment failures (Libby, French, Ltd., and King of Prussia)
• Brownouts (Keefe)
3.4 System Optimization and Modifications
Optimization and modification efforts that have been undertaken at the case study sites include
remedy refinement, pre-design modeling and testing, and system modifications. Exhibit 3-6
summarizes the types of optimization and modification efforts reported for the case study sites;
these are generally classified as pre-design and post-design efforts. Pre-design efforts at the case
study sites typically consisted of interim designs or systems (used at 13 sites) and groundwater
modeling (used at 11 sites). Post-design efforts consisted of optimization modeling (used at 13
sites), modifications of the groundwater extraction systems (used at twenty of the sites), and
modifications to the groundwater treatment systems (used at 15 sites). Exhibit 3-7 lists the
specific efforts made at each of the 28 sites.
At the time the case study reports were prepared, some of the sites at which remediation was
ongoing had identified plans for future system modifications. The following examples illustrate
these types of plans:
• At U.S. Aviex, further site characterization is needed and the remediation system may
require expansion.
• At City Industries, concentrations of contaminants in extracted groundwater may be low
enough to allow discharge directly to the POTW without prior treatment.
• At Sol Lynn, the system was shut down when extraction well pipes leaked and fouled, and
the extraction system had lost containment. Currently, the site is being reevaluated to
identify alternative remedial plans to address the issues with the extraction system.
3-8
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 3-6: Types of Optimization and Modification Efforts at 28 Sites1
Pre-Design
Interim Design or
System
• Pilot-scale system
• Demonstration
system
• Staged approach to
construction
• Treatability testing
• Interim system to
contain plume while
full system is
designed
Pre- or Post-Design
Groundwater/
Optimization Modeling
' MODFLOW
' MT3D
• Quickflow
• Randomwalk
• Biotrans
• (for most sites, the type
of modeling was not
specified)
Post-Design
Optimization/Modifications of Extraction System
Modifications | Purpose/ Objective
• Add extraction points • Increase extraction rate/
contain plume
• Abandon extraction points • Respond to reduction in
extent of contamination
• Resize extraction pumps • Increase efficiency of
system
• Adjust pumping rates • Increase efficiency of
system
• Change type of pump • Reduce shearing or
aeration of extracted
groundwater
• Modify extraction system • Increase efficiency of
design system or respond to
changes in remedial goals
• Use alternate remediation • Allow use of more cost-
method effective method (for
example, AS or natural
attenuation)
• Implement or expand • Respond to new source or
source controls increase efficiency in
treating existing source
areas
• Reduce performance • Reduce O&M costs
monitoring
Optimization/Modifications of Treatment System
Modifications | Purpose/ Objective
• Increase or reduce • Make capacity of treatment
equipment capacity plant match that of
extraction system
• Add chemical • Halt fouling of equipment;
enhancements to system enhance removal of
solids; enhance
biodegradation of
contaminants
•
• Add or replace with in situ • Increase performance or
technologies cost-effectiveness of the
system
• Upgrade process • Increase performance or
equipment cost-effectiveness of the
system
• Add process units to • Address unexpected
treatment train contaminants or increase
performance or efficiency
of system
• Automate treatment • Allow remote monitoring;
system operation reduce O&M cost
• Discontinue treatment • When discharge of
untreated water is
permitted
• Reduce compliance • Reduce O&M costs
monitoring
Notes:
1 Because the focus of the case studies was not on optimization, the types of optimization efforts listed in this table are not necessarily a comprehensive list of optimization efforts performed at all of
the case study sites.
3-9
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 3-7: System Optimization and Modification Efforts Conducted at 28 Sites1
Site Name
Baird and McGuire
SF Site
City Industries SF
Site
Des Moines TCE
SF Site
Former Firestone
Facility SF Site
Former Intersil, Inc.
Site
Pre-Design
Interim
Design
None identified
None identified
None identified
None identified
One extraction
well w/air
stripper to start
Groundwater
Modeling
System
Yes; provided
no details
None identified
Two-
dimensional
MODFLOW
Yes; provided
no details
Yes; provided
no details
Post-Design
Optimization
Modeling
Yes; provided
no details
Examined
varying
pumping rates
None identified
Yes; provided
no details
Yes; provided
no details
Modifications to Extraction System
Modification
Resized extraction
pumps
Increased pumping
from leading edge of
plume and decreased
pumping from
upgradient wells
None identified
Installed 10 additional
wells off-site/ adjusted
pumping rates/
increased overall
pumping rate for a 2
week period
None identified
Reason
Increase pumping rate to
meet design criteria
Maximize pumping
zones of influence
Not applicable
Prevent migration of
contaminated plume into
intermediate zones
Not applicable
Modifications to Treatment System
Modification
Enlarged sludge
thickener/replaced
bioreactor with air
stripper
None identified
AS media changed
from spherical to
chandelier type/
anti-corrosion and
biofouling agents
added to AS
None identified
P&T system
upgraded/switched
from P&T to PRB
in 1995
Reason
Enable treatment plant
unable to meet design
flowrate/maintain biomass
at design flowrates and
contaminant concentrations
Not applicable
Address iron corrosion and
biofouling of AS media
Not applicable
Reduce treatment costs and
allow for transfer of the
property
Table Continued...
Notes:
1 Because the focus of the case studies was not on optimization, the optimization efforts listed in this table are not necessarily a comprehensive list of optimization efforts performed at the case study
sites.
3-10
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 3-7: System Optimization and Modification Efforts Conducted at 28 Sites1
Site Name
French, Ltd. SF Site
Gold Coast SF Site
JMT Facility RCRA
Site (formerly Black
& Decker)
Keefe
Environmental
Services SF Site
King of Prussia
Technical
Corporation SF Site
LaSalle Electrical
SF Site
Pre-Design
Interim
Design
Staged
approach
None identified
Pilot test
None identified
None identified
None identified
Groundwater
Modeling
System
None identified
None identified
None identified
Yes; provided
no details
MODFLOW
andMTSD
None identified
Post-Design
Optimization
Modeling
MODFLOW
and Biotrans
None identified
None identified
Yes; provided
no details
Ongoing, using
MODFLOW
andMTSD
None identified
Modifications to Extraction System
Modification
None identified
Enlarged two
extraction wells/shut
down system for four
months/conducted air
sparging in "source"
areas/added peroxide
to wells for a period,
with no effect
Conducted full-scale
rehabilitation of
extraction well/
installed an electrical
and piping box at
extraction well
Constructed two
replacement extraction
wells
None identified
None - original design
considered adequate
Reason
Not applicable
Increase extraction rate/
increase amount of TCE
and PCE desorbing from
soil
Unclog well/minimize
time to perform routine
maintenance checks on
system
Optimize system after
reevaluation because
cleanup goals were not
being met
Not applicable
Not applicable
Modifications to Treatment System
Modification
Added second
sheet-pile wall
around DNAPL/
shut system down
in 12/95
None identified
Constructed
enclosure around
the treatment
system
None identified
None identified
None - original
design considered
adequate
Reason
Address DNAPL detected/
continue remediation of the
site via natural attenuation,
as specified in the site ROD
Not applicable
Consolidate system
operation in one building
Not applicable
Not applicable
Not applicable
Table Continued...
Notes:
1 Because the focus of the case studies was not on optimization, the optimization efforts listed in this table are not necessarily a comprehensive list of optimization efforts performed at the case study
sites.
3-11
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 3-7: System Optimization and Modification Efforts Conducted at 28 Sites1
Site Name
Libby Groundwater
SF Site
Mid-South Wood
Products SF Site
Moffett Federal
Airfield
Mystery Bridge at
Highway 20 SF
Site, Dow/DSI
Facility
Odessa Chromium I
SF Site
Odessa Chromium
IIS SF Site
Old Mill SF Site
Pre-Design
Interim
Design
Pilot test and
demonstration
for in situ
bioremediation
1 985-89 french
drains
Currently in
pilot-test stage
None identified
30-day pilot
study
30-day pilot
study
None identified
Groundwater
Modeling
System
None identified
None identified
None identified
Quickflow
Randomwalk
and Geoflow
Randomwalk
and Geoflow
None identified
Post-Design
Optimization
Modeling
None identified
None identified
None identified
None identified
Yes; provided
no details
Yes; provided
no details
None identified
Modifications to Extraction System
Modification
Tested and converted
to lower-shear pumps/
four extraction wells
abandoned, and one
new well constructed
Removed five
extraction wells/
continuously adjusted
pumping schedule of
extraction wells
None identified
None identified
Added three injection
wells/converted two
monitoring wells to
recovery wells
Added two injection
wells/installed
recovery well
Added three collection
trenches
Reason
Increase effectiveness of
OWS/address decrease in
areal extent of
contamination
No contaminants
detected in the five wells/
schedule adjusted
according to
concentration results
Not applicable
Not applicable
Achieve higher injection
rate/attempt to fully
capture plume
Achieve higher injection
rate/expedite cleaning of
source area
Address new areas of
contamination
discovered
Modifications to Treatment System
Modification
Peroxide system
for aeration of ISB
source water
replaced with
bubbleless system
Added carbon
treatment system
for one year
None identified
None identified
Added chamber to
reaction tank/
added backwash
unit for filter
Added chamber to
reaction tank/
added a backwash
unit
Replaced two
carbon canisters
with one
Reason
Minimize treatment costs
Allow for use of treated
groundwater in production
facility
Not applicable
Not applicable
Precipitate iron before
stripping and filtering
Precipitate iron before
stripping and filtering
Eliminate over design
Table Continued...
Notes:
1 Because the focus of the case studies was not on optimization, the optimization efforts listed in this table are not necessarily a comprehensive list of optimization efforts performed at the case study
sites.
3-12
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 3-7: System Optimization and Modification Efforts Conducted at 28 Sites1
Site Name
SCRDI Dixiana SF
Site
Site A (Confidential
SF Site)
Sol Lynn/Industrial
Transformers SF
Site
Solid State Circuits
SF Site
Solvent Recovery
Services of New
England, Inc. SF
Site
Sylvester/Gilson
Road SF Site
Pre-Design
Interim
Design
1992-4 EPA
system/20
wells at 4 gpm
Bioremediation
study
None identified
None identified
None identified
4-well GW
circulation
Groundwater
Modeling
System
None identified
None identified
MODFLOW
None identified
None identified
None identified
Post-Design
Optimization
Modeling
Quickflow
None identified
MODFLOW
None identified
None identified
MODFLOW
Modifications to Extraction System
Modification
Added collection
trench/ reduced
extraction wells by
five (15 remain in
operation)
Expanded system by
adding more sparging
wells
Adjusted pumping
strategy because of
additional
contamination in the
silty aquifer identified
Added three wells off
site
None identified
Added six extraction
wells
Reason
Collect contaminated
groundwater from
shallow zone/achieve
more efficient hydraulic
control
Address additional
contamination
discovered during
demolition activities
Prevent cross-
contamination of zones
and prevent further
migration of
contaminants
Contain plume
Not applicable
Address hot spots
Modifications to Treatment System
Modification
Replaced tower air
stripper with
shallow-tray
stripper
None identified
None identified
Electronically
linked air stripper
blower to transfer
pumps so blower
would shut off
when not pumping
None identified
None identified
Reason
Tower air stripper was
struck by lightning
Not applicable
Not applicable
Prevent freezing problems
with blowers
Not applicable
Not applicable
Table Continued...
Notes:
1 Because the focus of the case studies was not on optimization, the optimization efforts listed in this table are not necessarily a comprehensive list of optimization efforts performed at the case study
sites.
3-13
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 3-7: System Optimization and Modification Efforts Conducted at 28 Sites1
Site Name
U.S. Aviex SF Site
U.S. Coast Guard
Support Center
United Chrome SF
Site
Western Processing
SF Site
Pre-Design
Interim
Design
1983-93
interim
remedial
measure
1994 pilot
study
None identified
None identified
Groundwater
Modeling
System
MODFLOW
and
Randomwalk
None identified
None identified
None identified
Post-Design
Optimization
Modeling
MODFLOW
and
Randomwalk
None identified
None identified
None identified
Modifications to Extraction System
Modification
Adjusted pumping
rates for each well
continuously
None identified
Turned off some
extraction wells/
flushed some areas
Discontinued
operation of 210
shallow well
points/installed deep
wells
Reason
Optimize system on the
basis of concentration
data for each well
Not applicable
Stop treatment in areas
with contaminant
concentrations below
cleanup levels/solubilize
contaminants in areas of
higher contamination
flushed
Address change in
remedial goal from
remediation to
containment
Modifications to Treatment System
Modification
Added pH
adjustment
None identified
Switched to
sending untreated
water to POTW/
injected deep
aquifer water into
upper aquifer
Added metals
precipitation to
treatment system/
replaced carbon
type
Reason
Reduce scaling of
equipment and discharge
piping
Not applicable
Minimize treatment costs/
discontinue rapid
dewatering of upper aquifer
Address severe fouling of
air stripping media/
minimize frequency of
carbon changouts required
Notes:
1 Because the focus of the case studies was not on optimization, the optimization efforts listed in this table are not necessarily a comprehensive list of optimization efforts performed at the case study
sites.
3-14
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
4.0 PERFORMANCE OF REMEDIAL SYSTEMS
AT 28 CASE STUDY SITES
Two of 28 sites have met all aquifer
restoration goals
Most sites have made progress
toward meeting remedial goals,
including reducing or eliminating a
hot spot within a plume, reducing the
mass of contaminants within a plume,
and reducing concentrations of
contaminants within a plume
This section discusses the performance of the
remedial systems used at the 28 sites in terms of
the remedial goals set for the sites and progress
made toward achieving those goals.
4.1 Remedial Goals
Remedial goals for the containment and
mitigation of contamination have been
established at all the case study sites. The
remedial goals for the sites included the restoration of all groundwater beneath the site and any
off-site groundwater that may have been affected by the site, as well as the containment of on-site
contamination, allowing off-site contamination to attenuate naturally. It should be noted that all
of the sites selected for case studies were chosen because they had established aquifer cleanup
goals and not just containment only goals, although goals at one site (Western Processing) have
been changed to containment only since the case studies were prepared. In addition, performance
goals for the treatment systems, such as requirements related to water discharge of water and air
emissions, were established for a number of the sites. Exhibit 4-1 identifies the goals established
for each site and whether the goals have been achieved.
Cleanup goals for the sites were established based on one or more of the following factors:
• Maximum contaminant levels (MCL)
• Primary drinking water standards
• Risk-based cleanup levels
• Approved alternative concentration limits (ACL)
• Optional cleanup levels for a non-time-constrained removal action
• Concentrations of contaminants in adjacent surface waters
For two-thirds of the sites, the aquifer goals established were based on MCLs.
Goals for the containment of contaminated groundwater were established for 25 of the 28 sites.
The manner of containment required at each site varied but typically consisted of containment of
the contaminated groundwater on-site or halting of the continued migration of an existing off-site
plume.
Limits on air emissions were identified for three of the sites (JMT, LaSalle, andLibby). During
preparation of the case study reports, EPA did not focus on whether air emission limits were
established; therefore, it is possible that the reports did not identify limits at some of the other
sites.
4-1
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 4-1: Summary of System Performance for 28 Sites
Site Name and Location
Baird and McGuire, MA
City Industries, FL
Des Moines, IA
Firestone, CA2
French, Ltd., TX
Gold Coast, FL2
Intersil, CA
JMT,NY
Keefe, NH
King of Prussia, NJ
LaSalle, IL
Libby, MT
Moffett, CA
MSWP, AR
Mystery Bridge, WY
Odessa I, TX
Odessa II, TX
Old Mill, OH
SCRDI Dixiana, SC
Site A, NY
Sol Lynn, TX
Solid State, MO
Solvent Recovery
Service, CT
Sylvester/Gilson Road,
NH
U.S. Aviex,MI
United Chrome, OR
USCG Center, NC
Western Processina. WA
Notes:
o
Q
NR
NE
Remedial
Technology
P&T
P&T
P&T
P&T
P&T, ISB
P&T, AS
P&T, AS,
PRB
P&T
P&T
P&T
P&T
P&T, ISB
PRB
P&T
P&T
P&T
P&T
P&T
P&T
P&T, AS, ISB
P&T
P&T
P&T
P&T
P&T
P&T
PRB
P&T
Remedial Goals
Restore
Aouifer
o
o
o
Q
o
Q
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
Contain
Plume
o
Q
Q
Q
Q
Q
Q
Q
Q
Q
NE
NE
Q
Q
NE
Q
Q
Q
Q
Q
o
Q
Q
Q
o
Q
o
Q
CleanuD Level Basis
MCLs, surface water
MCLs
MCLs
MCLs, drinking water
criteria, risk-based
risk-based
MCLs, drinking water
MCLs
MCLs
ACLs
MCLs
drinking water
MCLs, risk-based
drinking water
MCLs, risk-based
MCLs
MCLs
MCLs
risk-based
MCLs
MCLs
MCLs
MCLs
To be set
ACLs
MCLs
MCLs, risk-based
drinking water
MCLs
Goal established but not met
Goal established and met
Goal established, but performance not reported
Goal not established
Performance Goals
Air
Emission
NR
NR
NR
NR
NR
NR
NR
Q
NR
NR
Q
Q
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
NR
Water
Discharee
NR
Q
NR
Q
NR
Q
Q
Q
Q
Q
NR
NR
NE
o
Q
Q
Q
Q
Q
NR
Q
NR
Q
Q
Q
Q
NE
Q
Minimum
Maximum
Average
Median
Contaminant
Mass
Removed1
Total Pounds
2,100
2,700
30,000
500
510,000
2,000
120 (P&T);
15 (PRB)
840
68
5,400
130
37,000
NR
800
21
1,100
130
120
7
5,300
5,000
2,700
4,300
430,000
660
31,000
NR
100.000
7
510,000
43,000
2.000
For sites at which groundwater cleanups are ongoing, the total mass of contaminant removed represents the performance
reported as of late 1997 or early 1998. Contaminant mass removals were calculated based on various types of mass balances
around the site treatment system, not based on groundwater monitoring data. Insufficient data were available to calculate a
removal of contaminant mass by in situ bioremediation; for those sites at which used in situ bioremediation was used, the
contaminant mass removed may be greater than shown here.
Firestone and Gold Coast - remediation has been completed at these two sites.
4-2
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Contaminant Mass Removed
Exhibit 4-1 presents the contaminant mass removed for the case study sites. For 26 of the sites,
the mass of contaminant removed by the remediation systems was reported or could be calculated
from reported data. When concentration and throughput data for the treatment system were
available, these data were used to calculate the mass of the contaminant removed. Contaminant
mass removals calculated based on groundwater monitoring results were not available. Total
mass of contaminant removed ranged from seven pounds (SCRDI Dixiand) to 510,000 pounds
(French, Ltd.}, with an average of approximately 43,000 pounds and a median of approximately
2,000 pounds. For almost one-third of the sites, contaminant mass removed ranged from 1,000
to 10,000 pounds per site.
Because mass removal rates are dependent on many factors, including the extent and
concentration of the contamination, contaminant properties, and the volume of groundwater
treated, they generally are not used to evaluate the achievement of remedial goals. The
variability is demonstrated in Exhibit 4-2 which shows the average mass of contaminant removed
per year and per 1,000 gallons of water treated at each site. Contaminant mass removed per year
for the 26 sites varies from approximately two pounds to more than 100,000 pounds, and from
approximately 0.0001 pounds per 1,000 gallons treated to three pounds per 1,000 gallons treated.
Sites with relatively higher mass removal rates per year do not consistently show relatively
higher mass removal rates per 1,000 gallons treated. This may be due in part to differences in the
concentration of contamination in the extracted groundwater. In addition, while not completed
for this report (due to a lack of available data), a comparison of mass removal rates at a site over
time can generally be useful in evaluating changes in system performance, for example, in
identifying when removal rates are approaching asymptotic values (see the case studies for
Western Processing and Firestone}.
Reduction in Concentrations of Contaminants
Exhibit 4-3 presents the average reductions in concentrations of contaminants at the case study
sites, sorted by the number of years which the remediation system was in operation (for this
report, the number of years of performance data available). Average concentrations of
contaminants could be calculated on the basis of available data for 17 of the 28 case study sites.
For several of the sites, average concentrations of contaminations were reported only for a group
of contaminants, and several others reported average concentrations of contaminants by
individual contaminant. In addition, three of the sites (United Chrome, Odessa II, and French
Ltd.) reported individual average concentrations of contaminants for more than one aquifer.
4-3
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 4-2: Unit Contaminant Mass Removed at 26 Sites
1
SCRDI Dixicna
Mystery Bridge
Intersil
Qd Mill
Keefe
GddCecst
LcSdle
Cdsssall
Des Manes
JMT
MSWP
U.S.Aviex
Cdessal
French, Ltd.
SdidStde
BdrdcndMcGuire
S dvent Reccvery S ervice
Sd Lynn
Kingcf Prussia
Qly Indus fries
United Chrcme
SiteA
Libby
Wes tern P races s i ng
Sylvester/SilscnRocd
Firestcne
0.0001
10
100
pounds per year
1,000
10,000
100,000
1,000,000
0.001
0.01 0.1
pounds per 1,000 gallons
DMass Removed per 1,000 Gallons Treated
I Mass Removed per Year
4-4
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 4-3: Summary of Average Contaminant Concentration Reduction
at 17 Sites
Site Name and Location
Intersil, CA
Des Moines, IA
JMT,NY
United Chrome, OR
MSWP, AR4
Odessa I, TX
Gold Coast, FL
Odessa II, TX4
LaSalle, IL4
French, Ltd., TX
U.S. Aviex, MI
Keefe, NH
LaSalle, IL
City Industries, FL
King of Prussia, NJ
Baird and McGuire, MA
Site A, NY
Contaminant(s)
Basis1
Zone1
VOCs (4 contaminants)
VOCs (3 contaminants)
TCE
VOCs (4 contaminants)
TCE
Chromium
Chromium
Shallow Aquifer
Deep Aquifer
Metals/VOCs (4 contaminants)
As
PCP
Cr
Total PAHs
Chromium
PCE
TCE
Chromium
Chromium
PCBs/ VOCs
1,2-DCA
Vinyl chloride
Benzene
1,1,1-TCA
Perched Aquifer
Trinity Aquifer
Shallow Aquifer
SI Aquifer/TNT Aquifer
SI Aquifer/TNT Aquifer
SI Aquifer/TNT Aquifer
VOCs (10 contaminants)
VOCs (5 contaminants)
PCBs/ VOCs
Deep Aquifer
VOCs and SVOCs (16 contaminants)
Metals (6 contaminants)
VOCs (9 contaminants)
VOCs (specific contaminants not identified)
SVOCs (specific contaminants not identified)
BTEX
Average Contaminant
Concentration (|Jg/L)2
Start
1,609
87
45
950
450
1,923,000
1,400
140
3
22
30
35
980
176
88
180
400
400
256/917
129/420
516/640
107
158
80
100
3,121
3,500
4,500
500
1,000
160
End
31
10
3
30
7
18,000
110
90
4
11
5
23
540
1
1
190
50
570
0.8/1
1.2/1
0.6/2
40
67
18
6
444
1,500
4,000
420
520
26
Years
of
Data
11.1
9
9
8.6
8.6
8.6
8.6
7.1
7.1
7.1
7.1
7.1
5
4.9
4.9
4.8
4.8
4.2
3.9
3.9
3.9
3.6
3.6
3.5
3.2
3
2.6
2.6
1
1
1
Percent
Reduction3
98
89
93
97
98
99
92
36
-33
50
83
34
45
99
99
-6
88
-43
>99
>99
>99
63
58
78
94
86
57
11
16
48
84
Notes:
Data on average concentrations were reported for 17 of the 28 case study sites; for those sites, data are shown here by contaminant(s) and
zone; zones are noted only for those sites at which concentrations of contaminants were reported for more than one aquifer.
Average concentrations of contaminants are based on a reported geometric mean of all data, as presented in the case study reports; for sites
with ongoing cleanups, average concentrations of contaminants shown at "end" time represent the concentrations reported as of the date
that data were available, typically late 1997 or early 1998.
Percent reduction was calculated as the difference between average concentrations of contaminants at start and end points, divided by the
average concentration at the start.
Negative percent contaminant reductions were measured at three sites. These anomalies are discussed in the case studies for the sites.
4-5
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
4.2 Progress Toward Goals
Exhibit 4-4 lists the number of sites that have met specific remedial and system performance
goals.
Exhibit 4-4: System Performance Summary
Goal
Number of Sites with
Soeeified Goals *
Number of Sites Meeting
Snecified Goals
Remedial Goals
Aquifer Restoration
Containment
28
25
2
22
System Performance Goals
Air emissions 2
Discharge of water
3
19
3
18
Notes:
1 Goals for each site are specified in the case study reports.
2 Air emission goals were specifically identified for only three of the case study sites.
Gold Coast and Firestone are the two case study sites for which all remedial goals have been
met, as described briefly below.
• Gold Coast was a spent oil and solvent recovery facility that operated from 1970
to 1982. In the 1980s, groundwater was determined to be contaminated with
chlorinated and nonchlorinated VOCs at levels as high as 100 milligrams per liter.
A P&T system consisting of five extraction wells (pumping at a total of
approximately 100 gpm) and two air stripping towers was put on line in 1990. By
the end of 1994, concentrations of groundwater contaminants were reduced to
levels lower than cleanup standards, with the exception of one source area. A
limited air sparging effort was able to reduce the contaminant levels in that area to
levels lower than cleanup standards by 1995. The site is located over a porous
limestone aquifer, which facilitated groundwater pumping, and the use of source
controls and in situ technology were identified as key factors in the success of the
cleanup.
• The Firestone facility operated as a tire manufacturing plant from 1963 until
1980. In 1984, a 2.5-mile-long contaminated groundwater plume that contained
chlorinated solvents was identified. The primary target contaminant in the plume
was 1,1-DCE. A P&T system consisting of 35 extraction wells and ex situ air
stripping and carbon adsorption was put on line in 1986. By 1987, the
contaminated plume was contained and by 1992 the concentrations of 1,1-DCE in
the plume had been reduced to levels lower than the cleanup goals and the system
was shut down. During the operation of the groundwater extraction system, the
site operators frequently adjusted it to maintain maximum concentration of
contaminant at the treatment plant influent. That factor was identified as a key
one in the success of the cleanup.
4-6
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
In addition to the two sites listed above at which the specified aquifer cleanup goals have been
met, progress has been made toward meeting the specified remedial goals for most of the sites.
Example successes include:
• Meeting aquifer cleanup goals in one or more zones at the site
AtDesMoines, the cleanup goals for the off-site plume were achieved within two
years of startup of the remediation system. P&T continues to maintain an inward
hydraulic gradient and to remediate on-site groundwater. The aquifer at the site
is a relatively homogeneous formation of sand and gravel that has a relatively
high conductivity.
• Reducing the size of a contaminated plume
At Odessa I, the total plume area was reduced approximately 44 percent in two
years (from 1994 to 1996). On several occasions, the groundwater extraction
system was modified to improve efficiency.
• Reducing the concentrations of contaminants within a plume
At United Chrome, average concentrations of chromium were reduced in the
upper aquifer from more than 1,900 to 18 mg/L over nine years, and in the deep
aquifer from 1.4 to 0.11 mg/L over six years. On several occasions, the
groundwater extraction system was modified to target the more highly
contaminated areas of the plume.
• Removing contaminant mass from a plume
At French, Ltd., the P&T system removed approximately 517,000 pounds of
contaminant (measured as total organic carbon) from January 1992 through
December 1995. The mass was removed through aggressive pumping of
groundwater that contained relatively high concentrations of contaminants
(hundreds of mg/L) from more than 100 recovery wells.
• Achieving containment of a plume
At City Industries, the contaminated groundwater plume has been contained
hydraulically since the P&T system was put on line in 1994.
It is important to note that groundwater cleanup is ongoing at most of the case study sites;
therefore, the system performance presented in this report does not represent the final
performance to be achieved in remediating each of the sites. As discussed earlier, the data
presented in the case studies are generally available through late 1997 or early 1998.
4-7
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
4-8
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
5.0 COST OF REMEDIAL SYSTEMS AT 28 CASE STUDY SITES
This section discusses the costs of the remedial
systems at the 28 case study sites and unit costs
for the groundwater cleanups at these sites.
The costs for the sites typically were reported as
capital costs, operation and maintenance
(operating) costs, remedial design costs, and
other costs. For the purpose of this report,
calculated unit costs are provided as average
annual operating cost, capital cost per 1,000
gallons treated per year, and average annual
operating cost per 1,000 gallons treated per year.
Average annual operating cost as a percentage of
capital cost is also presented. Assumptions used
in reporting cost data are summarized below.
Capital and operating costs were
highly variable from site to site with
key cost drivers, including variable
monitoring requirements, significant
system modifications needed, and
size and complexity of the remedial
systems
The following three types of unit
costs were calculated for each site:
• Average operating cost per year of
operation
• Capital cost per 1,000 gallons
treated per year
• Average annual operating cost per
1,000 gallons treated per year
Cost data presented in the case study reports were based on data provided by EPA
remedial project managers, site owners, or vendors. The costs presented in this
report are based on the cost data in these case study reports. In addition, updated
cost data received in May 1999 for several of the sites (BctirdcmdMcGuire,
Libby, French Ltd., United Chrome, Sylvester/Gilson Road, Western Processing)
was included in this report. When actual cost data were not available, site
contacts provided estimates based on the best data available at the time.
Groundwater cleanup is ongoing at most of the sites; therefore, the operating costs
(and in some cases the capital costs) do not represent the total to be spent to
remediate a site. The data presented here generally are current as of late 1997 or
early 1998, with 1999 data available for the sites identified above.
Because groundwater cleanup is ongoing at most of the sites and the total time
necessary to complete cleanup of a site was not known, a net present value (NPV)
of the remedial costs for the sites was not calculated for this report. The systems
in the 28 case studies had been operating for as few as 2 years and as long as 11
years. While many feasibility studies conducted under Superfund assume a 30-
year duration to estimate the cost of a P&T remedy, the use of this timeframe was
not considered to be applicable for this report because the two completed projects
were completed in 3.5 and 7 years.
5-1
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Capital and operating costs were extracted from cost data provided in the case
studies based on the Recommended Cost Format in Guide to Documenting and
Managing Cost and Performance Information for Remediation Projects [4].
Capital costs included: technology mobilization, setup, and demobilization;
planning and preparation; site work; equipment and appurtenances; startup and
testing; and other technology capital costs. Operating costs included: labor;
materials; utilities and fuel; equipment ownership, rental, or lease; performance
testing and analysis (although compliance testing was often not separated out);
and other technology operating costs. Source controls, RI/FS, and system design
costs were not included as capital or operating costs. However, VCBs used for
hydraulic control were included as capital costs.
As previously discussed in Section 3.1, PRBs may differ in form and purpose
from P&T and PRB systems, and unit costs for sites at which PRBs were used are
shown separately from costs for sites at which P&T was used. PRBs treat only the
groundwater that passes through the barrier, while P&T actively extracts
groundwater from an aquifer. Therefore, the volume of groundwater treated by a
PRB will be relatively less than by a P&T system for the same size plume.
Cost Data
Exhibit 5-1 presents the cost data for cleanup of contaminated groundwater at each of the case
study sites. The table also identifies the major factors that influenced costs at each of the sites.
Exhibit 5-2 summarizes overall remedial costs and unit costs for P&T and PRB sites,
respectively, including minimum, maximum, average, and median costs for each of the two
groups individually and combined.
Capital costs per P&T site ranged from approximately $250,000 (Gold Coast) to $15 million
(Western Processing and French, Ltd.), and average annual operating costs ranged from
approximately $90,000 (MSWP) to $4.4 million (Western Processing). Average annual operating
costs ranged from 2.9 to 56 percent of the capital costs. The median capital cost was $1.9
million and the median average annual operating cost was $190,000; with median unit costs of
$96 of capital cost per average 1,000 gallons of groundwater treated per year and $ 18 of average
annual operating cost per average 1,000 gallons of groundwater treated per year.
Based on three sites, capital costs per PRB site ranged from approximately $370,000 (Mqffett) to
$600,000 (Intersil [PRB]), and average annual operating costs per PRB site ranged from
approximately $26,000 (Mojfeti) to $95,000 (Intersil [PRB]). Average annual operating costs
ranged from 6.9 to 17 percent of the capital costs. For the PRB systems, the approximate median
capital cost was $500,000 and the median average annual operating cost was $85,000; with
median unit costs of $520 of capital cost per average 1,000 gallons of groundwater treated per
year and $84 of average annual operating cost per average 1,000 gallons of groundwater treated
per year.
The total remedial cost for each site was not projected, since the number of years in which each
system has been operating and the progress of each system toward meeting remedial restoration
goals vary from system to system.
5-2
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 5-1: Summary of Cost Data for 28 Sites
1,2,3
Site Name and
Location
Years of
Operation
(with data
available)
Average
1,000
Gallons
Treated per
Year
Capital
Cost (S)
Average
Operating
Cost ($)
Per Year
P&T SITES
Baird and
McGuire, MA
City Industries,
FL
Des Moines, IA
Firestone, CA
French, Ltd. ,TX
Gold Coast, FL
Intersil (P&T),
CA
JMT,NY
3.8
3.0
8.8
6.8
4.0
3.7
7.3
9.6
21,000
50,000
554,000
266,000
76,000
22,000
5,000
5,200
11,000,000
1,200,000
1,600,000
4,100,000
15,000,000
250,000
330,000
880,000
2,000,000
170,000
110,000
1,300,000
3,400,000
120,000
140,000
150,000
Average
Operating Cost
as Fraction of
Capital Cost
0.18
0.14
0.07
0.31
0.21
0.49
0.43
0.17
Capital Cost Per
Volume of
Groundwater
Treated Per Year
(S/1,000 Gallons)
530
23
2.9
15
200
11
65
170
Average Annual
Operating Cost Per
Volume of
Groundwater
Treated Per Year
(S/1,000 Gallons)
97
3.3
0.21
4.9
43
5.6
28
29
Key Cost Drivers
Operating costs increased due to
the need to monitoring for a
wide range of contaminants and
for several full-time operators to
be onsite
Optimized pump rates;
bio fouling of air stripper
increased system downtime
Unit costs reflect economies of
scale
Frequent modifications to
system were required; cost of
analysis and data management
were high
Large system incorporating P&T
and ISB; oversight costs were
high
Optimized extraction wells; P&T
system required less than four
years to clean up site
Groundwater extraction system
was expanded after three years
of operation, likely increasing
operating costs
Modifications of treatment
system increased capital costs 35
percent; system consisted of one
extraction well
5-3
Table Continued...
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 5-1: Summary of Cost Data for 28 Sites
1,2,3
Site Name and
Location
Keefe, NH
King of Prussia,
NJ
LaSalle, IL
Libby, MT
MSWP, AR
Mystery Bridge,
WY
Odessa I ,TX
Odessa II, TX
Years of
Operation
(with data
available)
4.1
2.7
4.4
5.3
8.3
3.6
4.2
4.1
Average
1,000
Gallons
Treated per
Year
11,000
57,000
5,200
2,900
12,000
54,000
30,000
30,000
Capital
Cost (S)
1,600,000
2,000,000
5,300,000
3,000,000
470,000
310,000
2,000,000
2,000,000
Average
Operating
Cost ($)
Per Year
240,000
390,000
190,000
500,000
91,000
170,000
190,000
140,000
Average
Operating Cost
as Fraction of
Capital Cost
0.15
0.19
0.03
0.17
0.19
0.56
0.10
0.07
Capital Cost Per
Volume of
Groundwater
Treated Per Year
(S/1,000 Gallons)
140
36
1,000
1,000
38
5.7
65
65
Average Annual
Operating Cost Per
Volume of
Groundwater
Treated Per Year
(S/1,000 Gallons)
21
6.8
36
170
7.4
3.2
6.3
4.6
Key Cost Drivers
Optimization of the system
pumping rates increased mass
removal efficiency
Electrochemical treatment
increased costs
Complex mixture of
contaminants and DNAPL
contributed to elevated capital
costs
Chemical costs (e.g., hydrogen
peroxide) were high for in situ
bioremediation; monitoring,
sampling, and analysis costs
were high at the beginning of the
project
Use of fabric filters increased
operating life of GAC units
Low concentrations in
groundwater
ROD required that ferrous iron
be produced onsite
electrochemically, limiting
number of appropriate vendors
and increasing capital costs
ROD required that ferrous iron
be produced onsite
electrochemically, limiting
number of appropriate vendors
and increasing capital costs
5-4
Table Continued...
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 5-1: Summary of Cost Data for 28 Sites
1,2,3
Site Name and
Location
Old Mill, OH
SCRDI Dixiana,
SC
Site A, NY
Sol Lynn, TX
Solid State, MO
Solvent
Recovery
Service, CT
Sylvester/Gilson
Road, NH
U.S. Aviex, MI
Years of
Operation
(with data
available)
7.8
4.6
1.3
3.0
4.2
2.9
9.5
3.4
Average
1,000
Gallons
Treated per
Year
1,700
4,500
6,700
4,300
62,000
11,000
126,000
96,000
Capital
Cost (S)
1,600,000
1,800,000
1,400,000
2,100,000
930,000
4,400,000
7,200,000
1,400,000
Average
Operating
Cost ($)
Per Year
210,000
94,000
290,000
150,000
370,000
400,000
1,900,000
180,000
Average
Operating Cost
as Fraction of
Capital Cost
0.13
0.05
0.20
0.07
0.40
0.09
0.27
0.13
Capital Cost Per
Volume of
Groundwater
Treated Per Year
(S/1,000 Gallons)
960
410
210
490
15
390
57
15
Average Annual
Operating Cost Per
Volume of
Groundwater
Treated Per Year
(S/1,000 Gallons)
130
21
43
34
6
36
15
1.9
Key Cost Drivers
Modifications to the system
increased capital costs 22
percent
PRP made major modifications
to the remedial system; relatively
low contaminant concentration
Use of skid-mounted modular
equipment reduced capital costs;
treatment system included air
sparging and in situ
bioremediation
Complex hydrogeology
increased capital costs
Capital costs do not include
costs for installation of four deep
extraction wells installed as part
ofRI/FS
Presence of DNAPL contributed
to elevated capital and operating
costs
Several full-time operators were
on site 24 hours per day, high
costs for fuel oil to operate the
vapor incinerator used for air
emission control
Optimization of interim P&T
system before final remedy
reduced costs
5-5
Table Continued...
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 5-1: Summary of Cost Data for 28 Sites
1,2,3
Site Name and
Location
United Chrome,
OR
Western
Processing, WA
Years of
Operation
(with data
available)
8.6
8.2
Average
1,000
Gallons
Treated per
Year
7,200
119,000
Capital
Cost (S)
3,300,000
15,000,000
Average
Operating
Cost ($)
Per Year
96,000
4,400,00$
Average
Operating Cost
as Fraction of
Capital Cost
0.03
0.30
Capital Cost Per
Volume of
Groundwater
Treated Per Year
(S/1,000 Gallons)
460
13?4)
Average Annual
Operating Cost Per
Volume of
Groundwater
Treated Per Year
(S/1,000 Gallons)
13
3l
Key Cost Drivers
Modular treatment system used
initially, reducing costs
Initially used large complex
system with over 200 vacuum
well points, 24-hour oversight
required; frequent maintenance
to control iron precipitate
buildup
PRB SITES
Intersil (PRB),
CA
Moffett, CA
USCG Center,
NC
1.8
1.2
1.0
1,100
200
2,600
600,000
370,000
500,000
95,000
26,000
85,000
0.16
0.07
0.17
520
1,600
190
83
110
33
P&T was replaced by PRB,
reducing operating cost (see
above)
Demonstration-scale project;
increased performance
monitoring was required for
technology validation
Use of PRB was estimated to
save $4 million over a typical
P&T system
Note:
Groundwater cleanups are ongoing almost sites; data presented here generally are current of late 1997 or early 1998.
Capital and operating costs were extracted from costs provided in the case studies based on the Recommended Cost Format in Guide to
Documenting and Managing Cost and Performance Information for Remediation Projects [4]. Source controls, RI/FS, and system design costs
were not included as capital or operating costs.
Cost data shown in the case study reports were based on data provided by EPA remedial project managers, site owners, or vendors. The costs
presented in this report are based on the total costs available at the time the case study report for the site was prepared and updated cost data
received in May 1999 for several of the sites (Baird andMcGuire, Libby, French Ltd., United Chrome, Sylvester/Gilson Road, Western
Processing). When actual cost data were not available, site contacts provided estimates based on the best data available at the time.
The P&T system at Western processing was changed in response to a change in the remedial goals at the site from aquifer cleanup to
containment. The modified system pumped less than half of the water pumped by the original system. However, for this report, data were not
available to determine the cost implications of the system modification.
Table Continued.
5-6
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 5-2: Summary of Remedial Cost and Unit Cost Data for 28 Sites
1,2,3
Cost Category
Years of System Operation (with
data available)
Average Volume of Groundwater
Treated Per Year (1,000 Gallons)
Total Capital Cost ($)
Average Operating Cost Per
Year ($)
Average Operating Cost Fraction
of Capital Cost
Capital Cost Per Volume of
Groundwater Treated Per Year
($71,000 Gallons)
Average Annual Operating Cost
Volume of Groundwater Treated
Per Year ($71,000 Gallons)
P&T Sites (26 sites)
Range
1.3 - 9.6
1,700 - 550,000
250,000 - 15,000,000
91,000 - 4,400,000
0.03 - 0.56
2.9 - 1,000
0.21 - 170
Median
Average
4.2
5.3
21,000
63,000
1,900,000
3,500,000
190,000
670,000
0.17
0.20
96
250
18
31
PRB Sites (3 sites)
Range
1.0 - 1.8
230 - 2,600
370,000 - 600,000
26,000 - 95,000
0.07 - 0.17
192 - 1,600
33 - 110
Median
Average
1.2
1.3
1,100
1,300
500,00
490,000
85,000
69,000
0.16
0.13
520
780
84
76
All Sites (28 sites)
Range
1.0 - 9.6
230 - 550,000
250,000 - 15,000,000
26,000 - 4,400,000
0.03 - 0.56
2.9 - 1,600
0.21 - 170
Median
Average
4.1
4.9
12,000
57,000
1,600,000
3,200,000
180,000
610,000
0.17
0.19
140
310
21
36
Notes:
i
Groundwater cleanups are ongoing at most sites; data presented here generally are cumulative as of late 1997 or early 1998.
Capital and operating costs were extracted from costs provided in the case studies based on the Recommended Cost Format in Guide to Documenting and
Managing Cost and Performance Information for Remediation Projects [4]. Source controls, RI/FS, and system design costs were not included as capital
or operating costs.
Cost data shown in the case study reports were based on data provided by EPA remedial project managers, site owners, or vendors. The costs presented
in this report are based on the total costs available at the time the case study report for the site was prepared and updated cost data received in May 1999
for several of the sites (Baird andMcGuire, Libby, French Ltd., United Chrome, Sylvester/Gilson Road, Western Processing). When actual cost data were
not available, site contacts provided estimates based on the best data available at the time.
5-7
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Calculated Unit Costs
Calculated unit costs are used to compare and contrast remediation technologies. Although the
basis and methodology for calculation of unit costs for site cleanups are still a matter of some
debate, some unit costs can be used to compare costs and performance at ongoing and completed
cleanup efforts and in identifying cost-efficient remedial strategies for future cleanups. For this
report, the following three types of unit costs were calculated for each site:
• Average operating cost per year of operation
• Capital cost per 1,000 gallons of groundwater treated per year
• Average annual operating cost per 1,000 gallons of groundwater treated per year
Those unit costs, along with their ranges, averages, and medians are summarized in Exhibits 5-1
and 5-2 and depicted in Exhibits 5-3, 5-4, and 5-5, respectively. The three unit costs summarized
for the case study sites are described briefly below.
Average Operating Cost per Year of Operation
The average operating cost per year is determined by the throughput of the system and the
treatment processes required to treat the extracted groundwater, as well as the operating
efficiency of the system. Since a breakdown of annual operating costs by year was not available
for most of the sites, the change in operating costs over the life of a site's remediation system
could not be evaluated for the purposes of this report. The average annual operating costs were
calculated by dividing the total operating cost to date by the number of years represented by that
cost.
At SCRDI Dixicma, where approximately 40 gpm were pumped from 15 wells through a
relatively simple system and discharged to a POTW, the average annual operating cost
was $94,000 over 4.5 years. At French, Ltd., where approximately 190 gpm were
pumped from more than 100 wells through a more complex treatment system before being
reinjected into the aquifer, the average annual operating cost was more than $3.4 million
per year over 4 years.
Capital Cost per 1,000 Gallons of Groundwater Treated Per Year
The capital cost per 1,000 gallons treated per year represents the relative costs of installing
remedial systems of varying capacity. This unit cost is influenced by factors such as the aquifer
complexity (which influences the size and complexity of the system needed to extract the
contaminated groundwater), the types of contaminants targeted for treatment at the site (which
influences the treatment plant components needed to remove the contaminants), the water and air
discharge limits for the particular site (which is also factor into the treatment plant components
needed), and restoration goals (which reflects the difference between sites where a large volume
of groundwater is treated over a relatively short time frame to clean up an aquifer versus
pumping at a lesser rate to prevent a contaminated plume from migrating from the site).
5-8
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 5-3: Average Operating Cost Per Year at 28 Sites
Western Processing
French, Ltd.
Baird and McGuire
Sylvester/Gilson Road
Firestone
Libby
Solvent Recovery Service
King of Prussia
Solid State
Site A
Keefe
Old Mill
Odessa 1
LaSalle
U.S. Aviex
Mystery Bridge
City Industries
JMT
Sol Lynn
Intersil
Odessa II
Gold Coast
Des Moines
United Chrome
Intersil (PRB)
SCRDI Dixiana
MSWP
USCG Center (PRB)
Moffett (PRB)
^^^^^^^^^^^^^
I
^^^^^^^^^^^^^1
^^^^^^=^^^^^^=! ,
=======198 000
:::::::::::::::::::::::::^^ A 400 Of
====:=^ ====:=^ 3400000
====:=^ :::::::::::::::::::::::::::::l 9 000 000
EEEEEEEEEEEEEEEEEEEEESI 5 0 0 . 0 0
EEEEEEEEEEEEEEEEESil 390 000
EEEEEEEEEEEEEEEEEEI370 000
========1990 000
=====1940 000
=====1910 000
=1190,000
::::::::::::::::::::::::::|19n,000
==l 1RO 000
=1170 000
:::::::::::::::::::::| 17 0,000
=11 fin nnn
==1150 000
::::::=l 1 40 000
::::::=l 14 0,000
=3120 000
3110,000
96,000
95,000
94,000
31 ,000
5,000
::::::::::::::::::::::::::l 1,900, 000
:::::::::l 1 , 300 , 00 0
3
0
10,000 100,000 1,000,000 10,000,000
Average Operating Cost ($) Per Year
The following example illustrates the effect of the aquifer complexity and treatment plant
requirements on the capital cost per 1,000 gallons of groundwater treated annually.
At the Gold Coast site, groundwater in a relatively shallow and homogeneous aquifer
contaminated with TCE was extracted and treated by an air stripper alone before it was
discharged to surface water. The capital cost was $11 per 1,000 gallons of water
treated. This compares with a cost of$l, 020 per 1,000 gallons of water treated at the
LaSalle Site, where groundwater was extracted via a horizontal pumping regime and was
treated for a complex range of contaminants by a much more complex system. The
system consisted of two air strippers, both vapor and liquid-phase GAC, oil/water
separation, andpH adjustment.
5-9
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 5-4: Capital Cost Per 1,000 Gallons of Groundwater Treated
Per Year
Moffett (PRB)
Libby
LaSalle
Old Mill
Baird and McGuire
Intersil (PRB)
Sol Lynn
United Chrome
SCRDI Dixiana
Solvent Recovery Services
Site A
French, Ltd.
USCG Center
JMT
Keefe
Western Processing
Intersil (P&T)
Odessa I
Odessa IIS
Sylvester/Gilson Road
MSWP
King of Prussia
City Industries
Firestone
Solid State
U.S. Aviex
Gold Coast
Mystery Bridge
Des Moines
::::::::::::::::::::::::::::::::::=^^
^^^^^^^^^=^^^^^^^^^^^^^^^^^ SJU
:::::::::::::::::::::::::::::::::::=^^ 490
^^^^^^^^^=^^^^^^^^^^^^^^^^=, 4bu
^^^^^^^^^^^^^^^^^^^^^^^^^^^^=1 410
^^^^^^^^^=^^^^^^^^^^^^=1 -ZTU
1 ZUU
^^^^^^^^^^^^^^^^^^^^^^^^^ 190
^^^^^^^^^=^^^^^^^^^^^=1 T/u
^^^^^^^^^^^^^^^^^^^^^^^^ 140
:::::::::::::::::::::::::::::::::::=^^ D
::::::::::::::::::::::::::::::::::| 3
::::::::::::::::::::::::::::=^^ 65
^^^^=^^^^^( 65
^^^=^^^=1 3 1
::::::::::::::::::::::::::::::::::::=| 36
I::::::::::::::::::::::::, ^j
__| .^
:::::::::::| 15
3 11
1,000
1,000
960
1 10 100 1,000 10,000
Capital Cost Per Volume of Groundwater Treated Per Year ($/1,000 Gallons)
5-10
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Exhibit 5-5: Average Annual Operating Cost per 1,000 Gallons of
Groundwater Treated Per Year
Libby
Old Mill
Moffett (PRB)
City Industries
Intersil (PRB)
French, Ltd.
Site A
Western Processing
LaSalle
Solvent Recovery Services
Sol Lynn
USCG Center
JMT
Intersil (P&T)
Keefe
SCRDI Dixiana
Sylvester/Gilson Road
United Chrome
MSWP
King of Prussia
Odessa 1
Solid State
Gold Coast
Firestone
Odessa IIS
Des Moines
Mystery Bridge
U.S. Aviex
Baird and McGuire
::::::::::::::::::::::::::::=^^ 1 30
:::::::::::::::::::::::::::::::::^^ I lu
:::::::::::::::::::::=^
::::::::::::::::::::::=^^ 43
^^^^^^^^^=^^^^^^ 43
::::::::::::::::::::::::::::=^^ 3,
:::::::::::::::::::::::::::::::::^^ 3o
i±±±^±l 36
•• 0.2
^^^^^^^^=^^^^=1 34
:::::::::::::::::::::::::::::::::::=^^ 33
:::::::::::::::::::::=^ 2»
::::::::::::::::::::::=^^ 28
^^^^^^^^^^=1 21
:::::::::::::::::::::::::=^ 21
^^^^^=^^^^^ ::::::=1 | 5
^^^^=^^^^= =1 1 3
[[[| /
::::::::::::::::::::::=^^ /
1 D
I[[[ | 6
====:=^ 0
i 5
=========} 3
::::::::::::::::::::::::::::::::::| 3
::::::::::::::::::::::::::::::::::l 3
::::::::::::::::::::, 2
97
83
0.1 1.0 10.0 100.0 1,000.0
-------
Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Average Annual Operating Cost Per 1,000 Gallons of Groundwater Treated
Per Year
The average annual operating cost per 1,000 gallons of groundwater treated per year represents
the relative costs to operate systems of various capacities and complexities. Similar to the capital
cost per 1,000 gallons of groundwater treated per year, this unit cost is highly dependent on site-
specific factors such as the aquifer complexity, the types of contaminants targeted for treatment,
the water and air discharge limits, and the restoration goals.
The following example illustrates the effect of the complexity of a site treatment system on
average annual operating cost per 1,000 gallons of groundwater treated per year.
At Des Moines over 500 million gallons of groundwater were treated per year using a
relatively simple system consisting of an air stripper for an average annual operating
cost of $0.21 per 1,000 gallons of groundwater treated annually. Conversely, at Libby,
2.9 million gallons of groundwater were treated per year using a complex remediation
system consisting of oil/water separation, nutrient addition, and bioreactors for an
average annual operating cost of$l 73 per 1,000 gallons of groundwater treated
annually.
In general, systems that treat a relatively large volume of groundwater per year will cost less in
both capital and annual operating costs per 1,000 gallons of groundwater treated than a similar
system that treats a smaller volume of groundwater per year. While no specific correlation could
be derived based on the available information, the following example shows this trend.
The treatment systems at Des Moines, City Industries, and Mystery Bridge consisted of
P&T using air stripping as aboveground treatment. Des Moines treated a relatively
larger volume of groundwater annually. The following table summarizes some of the
data for these sites.
Site Name
Des Moines, IA
City Industries, FL
Mystery Bridge, WY
Average Volume of
Groundwater
Treated Annually
(1,000 Gallons)
554,000
50,000
54,000
Average Annual
Operating Cost Per
Volume of
Groundwater
Treated Per Year
(S/1,000 Gallons)
0.21
3.3
3.2
The average annual operating cost per volume of groundwater treated annually
exemplifies the above trend.
5-12
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
6.0 FACTORS THAT AFFECTED COST AND PERFORMANCE OF
REMEDIAL SYSTEMS AT 28 CASE STUDY SITES
The factors that affected cost and performance at
the 28 case study sites vary and are specific to
each site. This section discusses the key factors
that affected cost and performance of the
groundwater cleanup at the case study sites
identified from the case studies and industry
knowledge about groundwater remediation. The
factors have been grouped into the categories
summarized in Exhibit 6-1.
The factors that affected cost and
performance at the 28 case study sites
vary and are specific to each site
No single factor was found to be the
most important factor in determining
cost and performance of groundwater
cleanup projects
Exhibit 6-1: Factors Affecting Cost and Performance
of Groundwater Remediation Systems
Category
Source control factors
Hydrogeologic factors
Contaminant property factors
Extent of contamination factors
Remedial goal factors
System design and operation
factors
Factors
Presence of NAPL; application and timing of source controls
Properties of the aquifer; contamination of more than one aquifer;
influence of surface water on aquifer; influence of adjacent groundwater
production wells on aquifer
Treatability of the contaminant; fate and transport properties of the
contaminant
Area and depth of contaminated plume; concentrations of contaminant
within the plume
Restoration of the aquifer rather than plume; MCL rather than less-
stringent cleanup levels; cleanup of the entire aquifer rather than partial
cleanup; time allowed for cleanup
System downtime; system optimization; amount and type of monitoring
performed; use of in situ technology
Each of the categories is discussed below; specific examples of how each factor affected cost or
performance of the groundwater cleanup systems at the case study sites are also presented.
Source Control Factors
Sources of groundwater contamination vary from surface discharges to buried wastes. When
source material comes in contact with groundwater, contaminants begin to dissolve and move
into the groundwater by advection and dispersion mechanisms. In addition, contaminant sources
in the vadose zone may act as continuing sources of groundwater contamination via leaching of
contaminants onto storm water recharge that passes through the contaminated zone.
Biodegradation and volatilization also may contribute to the destruction or dispersion of
contaminants. However, in many cases, the mechanisms may have a negligible impact.
6-1
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
The solubilities of many common contaminants (such as chlorinated solvents) are relatively low,
and sources of those contaminants may remain in the subsurface for extended periods of time.
EPA has concluded that one of the most effective means of remediating a site at which
contaminated groundwater is present is to remove, or at least isolate, the source material from the
groundwater. The source controls implemented at the case study sites (see Exhibit 3-2) include
such methods as removal of hot spots (soil), soil vapor extraction, capping, and installation of
VCBs.
NAPL has been observed or suspected to be a source of groundwater contamination at a majority
of the case study sites (see Exhibit 2-7). Of the 28 sites, NAPLs were observed or suspected to
be present at 18. At twelve of the sites, only DNAPL was present; at three, only LNAPL was
present; and at another three both DNAPL and LNAPL were present.
At several sites (such as French Ltd., SRS, and Western Processing), efforts were made to
remove or isolate the NAPL from contact with the groundwater. Such efforts often involved
significant capital expenditures.
At Western Processing, both DNAPL and LNAPL were observed in the groundwater. A
slurry wall was constructed around the site to contain the plume and help achieve the
cleanup goals within a limited amount of time. The slurry wall required capital
expenditures of approximately $1.4 million.
If NAPL was not removed or isolated, the groundwater remediation efforts often were hindered.
At Solvent Recovery Service, DNAPL is present in both the overburden and the bedrock
aquifers, and is a source from which a dissolved plume continually forms. Despite three
years of P&T operation, the complex hydrogeology and DNAPL present at this site have
resulted in fluctuating concentrations of total VOCs in the groundwater. Site
representatives indicated that they plan to apply for a technical impracticability (TI)
waiver because of the presence of the persistent source of DNAPL.
Hydrogeologic Factors
Hydrogeologic factors that influence the cost and performance of groundwater remediation
systems include the composition and hydraulic conductivity of a water-bearing layer; the depth to
groundwater; contamination of more than one aquifer; vertical groundwater flow; the influence
of surface water; and the influence of nearby groundwater production wells. These factors can
affect the complexity of the groundwater remediation system as well as the ability of the system
to meet the remedial goals at a site.
This report presents information about the hydrogeologic conditions at the 28 subject sites (see
Exhibit 2-8). The hydraulic conductivity of the contaminated water-bearing layer(s) at the sites
ranged from 0.023 ft/day to 1,200 ft/day, a range of more than six orders of magnitude. The
hydraulic conductivity also often varied within an individual site, such as United Chrome, where
the hydraulic conductivity in the upper aquifer was two orders of magnitude less than in the
lower aquifer. At more than one-half of the sites, contamination was present in more than one
water-bearing layer or aquifer. Seven of the sites exhibited vertical groundwater flow, 13 were
influenced by adjacent bodies of surface water, and production wells (municipal or otherwise)
6-2
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
were located in the vicinity of each of eight of the sites. Reported depths of the water table
ranged from zero (at ground surface) to 45 feet below ground surface.
The following examples illustrate specific cases hydrogeological factors affected the cost or
performance of the groundwater remediation technology implemented at a site.
Hydraulic Conductivity
AtJMT, the hydraulic conductivity in the contaminated bedrock aquifer was relatively
low (0.65 ft/day). To increase hydraulic conductivity, controlled blasting was carried out
to create an artificial fracture zone, which served as an interceptor drain in the bedrock
around the extraction well. While that approach increased the capital cost of the system
(by an undetermined amount), it allowed effective extraction groundwater from the unit
by one well screened in the new fracture zone.
Contamination of More Than One Aquifer
At SCRDI Dixiana, eight distinct soil layers have been identified within the upper 100
feet of soils, including five water-bearing units. Early site characterization work at the
site misidentified the thicknesses and degrees of contamination of several of those units.
Groundwater extraction wells were installed based on the results of that early work. The
wells were screened across two units, thereby presenting a pathway for contaminants to
migrate into a previously uncontaminated aquifer. In addition, the contaminated shallow
sand aquifer at the site was not identified until after the system had been installed,
resulting in the need to modify the remedial system to address multiple contaminated
aquifers.
Vertical Groundwater Flow
At Solid State, the groundwater system is a leaky artesian system in karst formations,
with shallow and deep bedrock zones separated by a semi-confining shale layer.
Groundwater flow at the site is vertical as well as lateral, a condition that has resulted in
contamination of multiple aquifers and the need to extract groundwater at several depths.
Influence of Bodies of Surface Water
At Site A, the groundwater flow is subject to tidal influence in the upper few feet of the
upper-most aquifer. Water levels at the site sometimes have risen, and SVE wells at the
site have been flooded.
Influence of Groundwater Production Wells
AtDesMoines, groundwater flow is to the southeast; however, earlier high-volume
pumping from city wells may have affected the flow direction, facilitating the migration of
the contaminant plume.
6-3
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Contaminant Property Factors
The types and properties of the contaminants being treated at a site, such as whether the
contaminant has a tendency to be removed with extracted groundwater or to stay adsorbed to
subsurface soils, can affect the cost or performance of a remediation system. In addition, the
properties of the contaminants determine what treatment technologies are appropriate and the
complexity of the system required to treat contaminated groundwater ex situ or in situ. Examples
of sites where the contaminants (see Exhibits 2-4 and 2-5) and the contaminant properties
affected the cost or performance of the groundwater remediation are presented below.
Complex Mixture of Contaminants
At Sylvester/Gilson Road, contaminants included chlorinated solvents, such as methylene
chloride; nonchlorinated organics, such as toluene and phenols; and the metal selenium.
The mix of contaminants was treated above ground by a long series of operations,
includingpH adjustment, settling, neutralization, filtration, air stripping with vapor
incineration, and biological treatment.
Single Contaminant That was Relatively Easy to Treat
AtJMT, groundwater was contaminated with chlorinated solvents. The groundwater
treatment system consisted of only an air stripper, which was capable of reducing
contaminant concentrations to a level where the treated groundwater could be
discharged to an adjacent surface water body.
Extent of Contamination Factors
Groundwater contamination concentrated in an isolated areal and vertical extent typically is
easier and cheaper to remediate than the same mass of contaminant when it extends deeper and
spreads out over a larger area. This factor affects the size of the extraction and treatment system
and the system complexity in terms of the quantity of groundwater to be extracted from the
aquifer and treated ex situ. The volumes of contaminant plumes at each of the sites are presented
in Exhibit 2-6. The following examples show the effects of a relatively small and relatively large
extent of contamination at which groundwater remediation has been completed.
At Gold Coast, the initial areal extent of the contaminant plume was estimated to be 0.87
acres, and the initial volume of the plume was estimated to be less than 3 million gallons.
The site was remediated at a cost of less than $700,000.
At the Former Firestone facility, the initial areal extent of plume was estimated to be 100
acres (1,300 feet wide and 3,400 feet long), with an initial volume of as much as 2.9
billion gallons. The cost to remediate this site was nearly $13,000,000.
6-4
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Remedial Goal Factors
Remedial goal factors that may affect the cost and performance of a site cleanup include the
stringency of the cleanup levels, the types of remedial goals, the types of performance
requirements that have been established for the remediation as well as the system complexity
required to meet these goals. The following remedial goal factors can influence the volume or
areal extent of groundwater that must be treated, the type of treatment train that may be used, or
the length of time that a system has to be operated.
• Stringency of the cleanup levels
> maximum contaminant levels
*• approved alternate concentration limits
>• risk factors
*• other criteria
• Types of remedial goals
>• aquifer restoration
*• aquifer restoration and containment
>• other restoration goals
• Types of performance requirements
*• treated wastewater discharge limits
> air emission limits
More stringent cleanup levels can require more complex systems, longer periods of operation,
and larger volumes of groundwater to be treated. The type or stringency of the performance
goals (treatment of extracted groundwater and/or air emissions) affect the manner and the extent
to which extracted groundwater or off-gas from the remediation system must be treated before
discharge. The following examples show the effects of various remedial goals on the cost and
performance of site cleanup.
Types of Remedial Goals
At Western Processing, an aggressive P&T system, consisting of more than 200
groundwater extraction points pumping approximately 265 gpm, was installed to pursue
aquifer restorations goals. After approximately seven years of operation, an ESD was
issued to change the focus of remediation from restoration to containment. As a result of
this change, the system was modified to a system pumping approximately 80 gpm. This
modification significantly reduced the operating cost for the system.
Performance Goals Established
At Solid State, the site engineer identified institutional constraints that restricted the
operator's ability to reinject treated groundwater. Reinjection of groundwater may have
been a more cost efficient method for the disposal of treated groundwater, and could
have increased groundwater flow through the contaminated zone. This restriction is
believed to have increased the time required for site remediation more than any other
single factor.
6-5
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
In addition, as shown at the French, Ltd. site, different remedies specified in a site ROD can
impact cost and performance.
Under the ROD for French Ltd., modeling was used as a basis to select natural
attenuation as a component of the site remedy. Modeling showed that concentrations at
the boundaries of the site would be acceptable after 10 years of natural attenuation, and
that P&T, which was costing more than $3 million annually, could be terminated.
System Design and Operation Factors
In addition to site characteristics and remedial goals, system design and operation can affect cost
and performance during remediation. System operation factors include the amount of time the
system is operational and the adequacy of the system design to handle the nature and extent of
the contaminants. For example, the long percentages of downtime for a system (see Exhibit 3-5)
or problems with system design can increase the cost of a site cleanup. Conversely, various
efforts in system optimization at a site (as detailed in Exhibit 3-7) can reduce the cost of a site
cleanup and/or improve the performance of a system. Described below are examples in which
system operation factors affected the cost or performance at case study sites.
System Downtime
At King of Prussia, the treatment system has been operational approximately 7 6 per cent
of the time. Downtime has been caused by several factors, including the need to shut the
system down for two months to repair a crack in a filter, and has increased operating
costs.
System Optimization and Modification
After two years of operation, site engineers at Keefe performed an optimization study. As
a result, two new wells were installed at locations that would increase groundwater
extraction rates. Also, two existing wells were taken offline. Both extraction rates and
contaminant mass flux to the treatment system increased as a result of the modifications,
leading to more efficient capture of the plume.
When periodic groundwater monitoring results atMSWP indicated that aquifer cleanup
goals were met in five extraction wells, pumping from these wells was stopped and the
pumping rates from the other wells was adjusted to optimize system performance.
6-6
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
Additionally, the use of in situ technologies such as air sparging, ISB, and PRBs (see Exhibits
3-2 and 3-4) can lower the cost and improve performance of a remedial system. Because only
seven of the case study sites used in situ technologies, and similar technologies were used at very
few of these sites, it is not possible to draw significant conclusions about the effect of using in
situ technologies on the cost and performance of groundwater cleanups. However, two specific
examples of the effects of using in situ technologies are described below.
A t Intersil, the site owner replaced a P& T system that had been operating for eight years
with a PRB system. The PRB system continued to remove contaminant mass and reduce
concentrations of the contaminant in the aquifer, while minimizing the cost of treatment
and returning the site to sellable or leasable condition.
At Gold Coast, air sparging was used to mitigate elevated contaminant concentrations
around one well that was in a suspected source area. Once the contaminant levels in this
well were reduced, aquifer cleanup goals were able to be met, and the groundwater
remediation system at the site was able to be shut down.
6-7
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
6-8
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
7.0 REFERENCES
1. Cohen, R.M., J.W. Mercer, and R.M. Greenwald. 1998. EPA Ground Water Issue,
Design Guidelines for Conventional Pump-and-Treat Systems. EPA 540/S-97/504.
. September.
2. Federal Remediation Technologies Roundtable. 1998. Remediation Cost and
Performance Case Studies (28 total), . September.
3. Groundwater Remediation Technologies Analysis Center (GWRTAC). 1998.
Remediation Technologies, . July.
4. EPA. 1998. Guide to Documenting and Managing Cost and Performance Information
for Remediation Projects, Revised Version. EPA 542-B-98-007.
October.
5. EPA, Office of Emergency and Remedial Response (OERR). 1997. Cleaning Up the
Nation's Waste Sites: Markets and Technology Trends. EPA 542-R-96-005.
. April.*
6. U.S. Environmental Protection Agency (EPA), Office of Solid Waste and Emergency
Response (OS WER). 1997. Rules of Thumb for Superfund Remedy Selection. OSWER
Directive 9355.0-69, OSWER 9355.0-69, PB97-963301. EPA 540-R-97-013.
. August.*
7. EPA, OERR. 1996. GroundWater Cleanup at Superfund Sites. Directive 9283.1-11.
EPA 540-K-96/008. .
December.*
8. EPA, OERR. 1996. Presumptive Response Strategy and Ex Situ Treatment Technologies
for Contaminated Ground Water at CERCLA Sites: Final Guidance. Directive 9283.1-12.
EPA 540/R-96/023. .
October.
9. EPA, OERR. 1993. Guidance for Evaluating the Technical Impracticability of
Groundwater Restoration. Directive 9234.2-25.
. September.
10. EPA, R.S. Kerr Environmental Research Laboratory and OSWER. 1992. Estimating
Potential for Occurrence ofDNAPL at Superfund Sites. PB 92-963 338. Publication
9355.4-07FS. .
January. *
Available from the U.S. Department of Commerce National Technical Information
Service, 5285 Port Royal Road, Springfield, Virginia 22151; 1(800)553-6847
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Groundwater Cleanup: Overview of Operating Experience at 28 Sites
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