&EPA
United States
Environmental Protection
Agency
Economic Analysis of the
Implementation of Permeable
Reactive Barriers for
Remediation of Contaminated
Ground Water
Water Table
GW Flow
Permeable Reactive Barrier
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EPA/600/R-02/034
June 2002
of the
of
for of
by
Robert M. Powell and Patricia D. Powell
Powell & Associates Science Services
Las Vegas, Nevada 89123
Robert W. Puls
Subsurface Protection and Remediation Division
National Risk Management Research Laboratory
Ada, Oklahoma 74820
Prepared under subcontract to Dynamac Corporation
EPA Contract No, 68-C-99-256
Project Officer
David S. Burden
Subsurface Protection and Remediation Division
National Risk Management Research Laboratory
Ada, Oklahoma 74820
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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Notice
The U.S. Environmental Protection Agency through its Office of Research and
Development funded and managed the research described here under EPA
Contract No. 68-C-99-256 to Dynamac Corporation, Rockville, Maryland. It has
been subjected to the Agency's peer and administrative review, and it has been
approved for publication as an EPA document. Mention of trade names or
commercial products does not constitute endorsement or recommendation for use.
All research projects making conclusions or recommendations based on environ-
mental data and funded by the U.S. Environmental Protection Agency are required
to participate in the Agency Quality Assurance Program. This project did not
involve the collection or use of environmental data and, as such, did not require a
Quality Assurance Plan.
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Foreword
The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation's land, air, and water
resources. Under a mandate of national environmental laws, the Agency strives to formulate and implement actions
leading to a compatible balance between human activities and the ability of natural systems to support and nurture
life. To meet this mandate, EPA's research program is providing data and technical support for solving environmental
problems today and building a science knowledge base necessary to manage our ecological resources wisely, under-
stand how pollutants affect our health, and prevent or reduce environmental risks in the future.
The National Risk Management Research Laboratory (NRMRL) is the Agency's center for investigation of technologi-
cal and management approaches for preventing and reducing risks from pollution that threatens human health and
the environment. The focus of the Laboratory's research program is on methods and their cost-effectiveness for
prevention and control of pollution to air, land, water, and subsurface resources; protection of water quality in public
water systems; remediation of contaminated sites, sediments and ground water; prevention and control of indoor air
pollution; and restoration of ecosystems. NRMRL collaborates with both public and private sector partners to foster
technologies that reduce the cost of compliance and to anticipate emerging problems. NRMRL's research provides
solutions to environmental problems by: developing and promoting technologies that protect and improve the environ-
ment; advancing scientific and engineering information to support regulatory and policy decisions; and providing the
technical support and information transfer to ensure implementation of environmental regulations and strategies at
the national, state, and community levels.
Permeable reactive barriers are no longer perceived as a new or unproven in situ technology for ground-water
remediation. They are now recognized as a standard remedial option for site owners and remedial project managers
to consider when trying to decide which remedial technology is best suited for effective cleanup at hazardous waste
sites. This document provides information about the costs of applying this technology and should be useful in arriving
at these difficult decisions. The report summarizes cost data from 22 sites across the United States where permeable
reactive barriers have either been installed or were to be installed. While it is difficult to assemble comprehensive cost
data on new and developing technologies, every effort was made to obtain the most complete data set possible. The
information presented should be helpful in guiding technology selection at hazardous waste sites where ground water
has been seriously impacted.
This publication has been produced as part of the Laboratory's strategic long-term research plan. It is published and
made available by EPA's Office of Research and Development to assist the user community and to link researchers
with their clients.
Stephen G. Schmelling, Acting Director
Subsurface Protection and Remediation Division
National Risk Management Research Laboratory
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This report presents an analysis of the cost of using permeable reactive barriers to
remediate contaminated ground water. When possible, these costs are compared
with the cost of pump-and-treat technology for similar situations. Permeable
reactive barriers are no longer perceived as an innovative remediation technology
but are rapidly maturing and may be considered as a standard remediation
technology, similar to pump-and-treat.
PRB cost information was obtained from a variety of sources, including reports,
surveys, and interviews. Costs were broken out into four general categories: site
characterization, design, construction, and operation and maintenance. Subcat-
egories within these four further detailed the costs.
A novel approach to comparing treatment costs for PRBs is proposed and used. It
relies on describing costs perthe quantity of waterthat actually needs to be treated
rather than the typical P&T approach of dollars per gallon that enter the treatment
system whether contaminated or not.
Cost comparisons indicate that, depending upon the situation, implementing a PRB
can either be more or less expensive than a P&T in terms of capital expenditures,
but that routine operation and maintenance costs favor the PRBs. However, a
major unknown with regard to implementing PRBs is the potential need for
replacement or rejuvenation of the reactive media.
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Contents
Foreword iii
Abstract iv
Figures vi
Tables vii
SI Conversion Factors viii
1. Introduction 1
2. Purpose of the Report 2
3. PRB Sites Evaluated 2
4, Information Acquisition and Methodology 4
4.1 Online and print information sources 4
4.2 Telephone contacts 4
4.3 Emailed forms 4
4.4 Vendor visits 4
4.5 Information quality 4
4.6 Information storage and organization 5
4.7 Cost parameter breakdown 5
5. Economic Data for the Permeable Reactive Barrier Sites 5
5.1 Stated versus calculated costs for the PRB sites 5
5.2 PRB site characterization costs 6
5.3 PRB design costs 6
5.4 PRB construction costs 8
5.5 Major cost/capital cost component summaries 11
5.6 Operation and maintenance at the PRB sites 11
6. Economic Data forthe Pump-and-Treat Sites 15
6.1 P&Tatthe PRB sites 15
6.2 P&T at other sites 15
7. Cost Comparison of PRB versus P&T Technologies 19
7.1 Rationale and approach 19
7.2 PRB cost per 1000 gallons of treated water 19
7.3 P&T costs per 1000 gallons of treated water 23
7.4 Comparison of P&T and PRB unit costs at the PRB sites 23
8. Summary and Conclusions 25
References and Resources 26
Appendix A 27
Appendix B 29
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Figures
1. Bar plot of Stated Cost, Calculated Approximate 1 * Year Cost, and
Calculated Construction Cost for the PRB sites 7
2. PRB design cost breakdown for USCG Support Center, North Carolina 9
3. PRB design cost breakdown for Somersworth Landfill, New Hampshire 9
4. Major cost components for the PRB sites 12
5. Capital costs of the PRB sites 13
6, PRB construction costs versus P&T construction costs at the PRB sites 18
7. PRB O&M costs versus P&T O&M costs at the PRB sites 18
VI
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Tables
1, Basic PRB Site Information 3
2. PRB Stated Costs and Sources 6
3. Calculated PRB Costs Relative to Stated PRB Costs 7
4. Design Cost Breakdown for the PRB Sites 8
5. Construction Cost Breakdown for the PRB Sites 10
6. Major Cost Components for the PRB Sites 12
7. PRB Site Capital Cost Summary 13
8. O&M Costs forthe PRB Sites 15
9. PRB Information Relevant to Maintenance Costs 16
10. P&T Information forthe PRB Sites 17
11. Comparison of P&T Costs Versus PRB Costs 17
12. Ground-water Flow and Volume Data Relevant to a Unit Cost Evaluation 20
13. Present Value Calculation for Annual PRB Site O&M Costs,
Including 30-year Total as Present Value 21
14. Various Costs per 1000 Gallons of PRB-treated Water, Using O&M PV
Calculations and Factor 1 Estimated Annual Flow Through PRBs for a
30-year Period (Including Fe Maintenance Costs for Sites with Estimates) 22
15. Costs per 1000 Gallons Treated by PRB During a Single or Average Year,
Including Data from U.S. EPA, 1999 23
16. Evaluation of Reported O&M Unit Costs for Four Sites by
Modifying the Unit Basis 24
17. Evaluation of Reported P&T Versus PRB Unit Costs at the Intersil Site by
Modifying the Unit Basis 24
18. Comparison of Costs per 1000 Gallons of Treated Ground Water for
Construction and O&M Costs Using PRB and P&T Technologies at the
PRB Sites in this Study 24
VI i
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SI
Multiply
Area:
Flow rate:
Length:
Mass:
Volume:
Temperature:
Concentration:
Pressure:
Heating value:
English (US)
Units by
1 ft2
1 in2
1 gal/min
1 gal/min
1 MGD
1 ft
1 in
1 Ib
1 Ib
1 ft3
1 ft3
1gal
1 gal
°F-32
1 gr/ft3
1 gr/gal
1 !b/ft3
1 Ib/in2
1 Ib/in2
Btu/lb
Btu/scf
Factor
0.0929
6.452
6.31 x10-5
0.0631
43.81
0.3048
2.54
453.59
0.45359
28.316
0.028317
3.785
0.003785
0.55556
2.2884
0.0171
16.03
0.07031
6894.8
2326
37260
Metric (SI)
to get Units
m2
cm2
m3/s
Us
Us
m
cm
g
kg
L
m3
L
m3
°C
g/m3
9/L
g/L
kg/cm2
Newton/m2
Joules/kg
Joules/scm
Viil
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IX
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1. Introduction
During the past decade there have been numerous investigations into innovative remedial technologies that could
supplement or, preferably, entirely replace standard pump-and-treat (P&T) technologies for the treatment of contami-
nated ground water. These technologies have consisted of in situ treatments that can either transform the contaminants
into innocuous breakdown products or detoxify and immobilize them in the subsurface, hence minimizing or eliminating
their biospheric impacts,
Among the most promising of these innovative technologies are permeable reactive barriers (PRBs). Ratherthan serving
to constrain plume migration, PRBs are designed as conduits for the contaminated ground-water flow. As contaminated
water passes through the reactive zone of the PRB, the contaminants are either immobilized or chemically transformed
to a more desirable (e.g., less toxic, more readily biodegradable, etc.) state. Therefore, a PRB is a barrier to
contaminants, but not to ground-water flow. A permeable reactive subsurface barrier has been defined as:
"...an emplacement of reactive materials in the subsurface designed to intercept a contaminant plume,
provide a flow path through the reactive media, and transform the contaminants) into environmentally
acceptable forms to attain remediation concentration goals downgradient of the barrier." (Powell et al.,
1998)
During the past ten years, PRB technologies have been investigated at all scales, from batch and column studies to full
field-scale implementations, and tested for efficacy with a variety of contaminants. They have proven highly effective and
seen extensive implementation for the dechlorination of chlorinated hydrocarbons and the reductive precipitation of
chromate (Cr6* as CrO42~), in particular.
To date, more than 40 PRBs have been installed in the field to restore ground-water quality. Because of this a track
record for these systems is beginning to be established; therefore, it is now time to move PRB systems from the
"innovative" technology list into the toolbox of standard technologies that are routinely considered for remediation. With
this move comes the need to develop effective means of measuring cost versus performance of these systems relative
to the other standard technologies, such as P&T.
Some cost analyses of individual PRB systems have been done and in some cases compared to either P&T systems
already in operation at the site (O1 Hannesin, 1998) or proposed (U.S. DOD, 1999; Gavaskaretal., 2000) for the site. The
intent of this document is to further document PRB costs and cost-effectiveness versus standard P&T
technologies. Twenty separate PRB sites were used for the study, along with estimates for full-scale implementations at
two pilot sites. The sites vary significantly in many respects, making a direct comparison between them for total cost
potentially misleading. In addition to site-specific differences, such as hydrology and geology, some PRBs are pilot-scale
studies, some are full-scale remediations, and some of each of these two types have been used for PRB research
purposes. Costs have been broken down into as much level of detail as is available. This was done in an attempt to better
understand what sorts of factors and considerations lead to an increase or a decrease in the overall costs relative to the
same component at other sites. This breakdown also helps in the comparison of the PRB implementations at these sites
to actual or potential P&T systems located within the same contaminated milieu. Assumptions for these analyses
included ongoing remediation fora period of 30 years (for both the PRB and the P&T remediations), with replacement of
the reactive media within the PRBs at ten-year intervals (based on reactive inorganic ground-water constituents).
Potential alternatives to replacement are discussed later in this document.
The cost detail for the PRBs was broken down into four general categories: (1) site characterization, (2) design,
(3) construction, and (4) operation and maintenance. A fifth cost category would be needed when PRBs are used to
remediate radionuclides; i.e., the disposal of spent reactive materials. This is not a focus of this document. Within each
of these general categories, cost was broken down into as much detail as was available from the published information
and the contacts for the sites. However, for several of the sites the information was either not available or not
forthcoming. In some instances, concern was expressed that the information was confidential and the client would not
want it to be released. In others, it seems that the information was simply never considered at a finer level of detail than
these four broad categories. Some site contacts did not respond to our information requests. In these circumstances
other sources were sought, and occasionally located. Nevertheless, less detailed information is available for some of the
sites than is desirable from the standpoint of a comprehensive cost analysis.
Comparisons to (P&T) systems that were either implemented at or considered for these PRB sites are presented. Some
P&T data from other reports are also used as comparators to the PRB costs. The PRB and P&T unit values (e.g., dollars
per 1000 gallons treated) are developed and compared in a way that seems more appropriate for the PRB technology
than has been done in earlier reports.
In brief, it was found that the PRB implementations were sometimes more and sometimes less expensive to construct
than P&T systems. When periodic reactive media maintenance costs were excluded, the PRB systems were found
considerably cheaper to maintain for the same level of effectiveness or better. However, the lack of information, in
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particular on the longevity of reactive media in PRB systems, along with no proven maintenance methods other than
replacement, cause PRB cost estimates to be potentially highly inaccurate.
2. Purpose of the
Long considered the standard for ground-water remediation, P&T technologies have come under increasing scrutiny
during the past decade. Although still useful under appropriate circumstances, e.g., effecting some cleanup or
containment of contaminant hot-spots, such as free product, the limitations of pumping and treating ground water often
render it an imperfect technology for addressing contaminant plumes. These limitations have been addressed elsewhere
in general (Keely, 1989; NRC, 1994) and in the context of the usefulness of PRBs specifically (Powell and Powell, 1998).
However, there is a wealth of information available, including cost and design data, for P&T systems and it is both logical
and inevitable that they are considered as possible remedial actions for sites with contaminated ground water.
However, due to a heightened awareness of P&T technology limitations, it became increasingly important to evaluate
methods that were not subject to, or rendered ineffective by, these same factors. Slightly over a decade ago, researchers
at the University of Waterloo (Gillham, 1995) developed a technology that overcame many of the P&T limitations; i.e.,
using permeable barriers of reactive media in the subsurface to intercept contaminant plumes. During the ensuing
decade, PRB technology has been thoroughly investigated both in laboratory and field settings and is being successfully
used at many contaminated sites. Initially, many believed that PRB technology would be much cheaper than P&T both
in capital costs and annual operation and maintenance (O&M) costs. As the number of installations has grown, it has
become increasingly apparent that the capital costs of PRB installation are very dependent upon site characteristics and
plume dimensions. This is in addition to an added level of site characterization that is usually needed to ascertain proper
placement and design of the PRB. In several instances, it has been found that capital costs of PRB installation exceed
actual capital costs, or estimates, for P&T systems.
Nonetheless, even with higher capital costs, PRBs have been assumed to have much lower O&M costs than P&T
systems. Recently, however, the lower O&M costs have also been questioned. One report from U.S. EPA compared
ground-water cleanup costs at 28 sites, including three sites with PRB installations (U.S. EPA, 1999a). This report seems
to indicate that both the PRB capital costs and O&M costs, expressed as unit costs, are actually in the middle to high end
of the cost range relative to P&T systems. Such reports have caused concerns about whether the cost savings of PRB
systems are as important as once believed (RTDF, 2000). This is particularly so now that the potential need for periodic
reactive media replenishment or replacement has become known.
This report has been developed to further document PRB costs and attempt to determine the factors that have caused
PRB O&M costs to equal or exceed those of P&T systems as they are being reported, even when media maintenance
is not being considered in those reports. It was found that both the capital and O&M costs of PRB systems vary widely,
due to differences in site characteristics. However, it appears that reported unfavorable O&M comparisons (exclusive of
media maintenance) with P&T are largely due to the methods being used forthe unit comparisons. Additionally, there are
other intangible benefits to using PRB technology that do not often show up in cost comparisons.
3.
Table 1 provides some basic information about the PRB sites that were the subjects of this study. It provides the type of
PRB, in a general sense, whether the installation was a continuous trench, a funnel-and-gate system (F&G), or installed
using hydraulic fracturing of bedrock. However, it should be noted that there are numerous methods for creating a
continuous trench. These include the use of continuous trenching machines; the use of mandrels that are filled with
reactive media, driven into the subsurface (where one drive overlaps the previous to maintain continuity) then removed;
the installation of sheet pilings on either side of a zone to be trenched and filled; the use of guar gum gels to support open
trenches; and many others. Additionally, the choice of impermeable materials to use for the funnel sections of F&G
installations, as well as the means of installing the gates, can also vary widely. Information about such procedures at
these sites is generally available elsewhere (http://www.rtdf.org/: U.S. EPA, 1999b) and these techniques are not the
focus of this report. It is important to realize, however, that costs can be significantly affected by the PRB installation
procedures chosen.
Table 1 also provides information about the reactive media installed at these sites, the tonnage that was used and the
contaminants being treated. Zero-valence state iron, i.e., iron metal (ZVI, Fe(0), or Fe°), is the most commonly used
reactive media to date in PRB installations and is incorporated into 19 of the 20 sites included in this report. Zero-valent
iron has been shown to be extremely effective for degrading chlorinated hydrocarbons, causing the PCE -> TCE -> DCE
-> VC -> C2H2 reductive dechlorination series of reactions to occur rapidly in response to electrons provided by the iron.
The mechanisms and intermediate transitional species of these reactions, as well as the fact that they do not generally
occur with 100% stepwise dechlorination, are still being studied and are beyond the scope of this document, but have
been discussed in other publications (Powell et al., 1998; Roberts et al., 1996). ZVI is also extremely effective for
reductively precipitating Cr(VI) as chromate (CrO42- or HCrO4~) to Cr(lll) and immobilizing it in the subsurface (Powell
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Table 1. Basic PRB Site Information
Site
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF
Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing,
Fairfield, NJ
Industrial Site, Coffeyville,
KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7,
WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale
Est.
PRB Type
Trench
F&G
Trench
F&G
Trench
F&G
Trench
F&G
Hydr.
Frac./Perm.
Infill
Trench
F&G
Trench
Trench
Trench
Trench
Hydr.
Frac./Perm.
Infill
Trench
Trench
Trench
Trench
F&G
F&G
Reactive
Material
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Organic
Matter
Fe(0)
Fe(0)
Fe(0)
Organic
Matter
Fe(0)
Oxygen
furnace slag
Fe(0)
Fe(0)
Mass,
Tons
450
220
166
75
3552
59
650
324
250
720
70
742
400
425
205
49
360
0
1750
400
2518
108
Treated
Contaminants
TCE; Cr(VI)
TCE; c-1,2-DCE; VC;
Freon 1 1 3
PCE; TCE; cDCE;
tDCE; VC
TCE; 1,2-DCE; PCE
PCE; TCE; cDCE;
VC
PCE; TCE; DCE
TCE; 1,2-DCE; VC
PCE, TCE
TCE
1,1,1-TCA; PCE; TCE
TCE; 1,1,1-TCA
TCE; cDCE; VC
TCE; cDCE; VC
Ni; Fe; SO4
TCE; DCE; VC
PCE; TCE
TCE; cis-1,2-DCE;
VC
Cu, Zn, Cd, Ni
TCE, DCE, VC
Phosphate
TCE; 1,2-DCE; PCE
PCE; TCE; DCE
PRB
Scale
Full-scale
Full-scale
Pilot-scale
Pilot-scale
Full-scale
Pilot-scale
Full-scale
Full-scale
Full-scale
Full-scale
Full-scale
Full-scale
Full-scale
Full-scale
Pilot-scale
Pilot-scale
Full-scale
Pilot-scale
Full-scale
Full-scale
Full-scale
Full-scale
On -Site
P&T?
Estimated
Yes
Estimated
0
Estimated
0
Yes
No
ND
Estimated
ND
Estimated
ND
No
ND
ND
ND
ND
ND
ND
Estimated
Estimated
Research
Site?
Yes
No
No
Yes
No
Yes
No
No
No
No
No
No
No
No
Yes
No
No
No
No
No
No
No
et al., 1995; Blowes et al., 1997). It should be realized that many of the sites reporting the use of ZVI have mixed it with
pea gravel or sand to maintain high hydraulic conductivity in the PRB and to accommodate construction methods. Others
have included pyrite or other materials to effect some sort of chemical modification prior to or during the reactions with
the ZVI. Information about these modifications is also generally available elsewhere. Of the 20 PRB sites, three of them
are exclusively treating metals and/or inorganic compounds, and they are using organic matter (to remediate Ni, Fe,
sulfate) or oxygen furnace slag (to remediate phosphate).
A factor influencing the apparent costs of a site Is whether or not a full-scale or a pilot-scale PRB technology is
implemented. Fourteen of the sites included in this study are operating full-scale PRB implementations. Six are pilot-
scale systems that are, or have been, operated, and two are estimates of full-scale systems based on the results of the
pilot-scale PRBs at the sites. It was decided to include the two full-scale estimates in this analysis because they have
been very thoroughly planned and analyzed for cost, apparently better than many of the operating systems. They are
also based on the results of pilot tests at the same site that give the estimates an added degree of credibility. Another
factor that could influence the costs is whether or not the PRB was used merely as a remedial technology or whether
active PRB research was conducted at the site. Most of the sites have had some additional effort made towards
understanding the usefulness and effectiveness of the PRB installations, beyond that usually done for a toolbox remedial
technology. Four of the sites are clearly identified as research sites. At these locations activities far beyond the scope of
a traditional remedial application were carried out in order to better understand PRB technology.
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4. Information Acquisition Methodology
Information was gleaned from several sources in the process of compiling information for this report. These sources
included the Internet, published reports, contacts for the specific sites, and a visit to PRB technology license vendors
such as the University of Waterloo and EnviroMetal Technologies, Inc., in Waterloo, Ontario, Canada.
4.1. Online print information
A large amount of information about PRB technology in general, as well as site-specific applications of the technology,
is now available on the Internet. These sources include those established by federal and state government, specifically
for providing information on remediation techniques, as well as other private and corporate sites. Among the better
resources are:
The Groundwater Remediation Technologies Analysis Center (http://www.gwrtac.org/)
The Remediation Technologies Development Forum (http://www.rtdf.org/)
The Hazardous Waste Clean-up Information Web Site (http://www.clu-in.org/)
The Federal Remediation Technologies Roundtable (http://www.frtr.gov/)
Internet data were also searched and mined using Sherlock® technology (Apple Computer, Inc.) to locate less obvious
sources of information. Much of the detailed PRB and site information available on the Internet is available in Portable
Document Format® (PDF, Adobe, Inc.) and many documents of this sort were downloaded and searched for site
information with a particular focus on cost.
Numerous books and reports about PRB systems have been published by EPA, DOE, DOD and other governmental
bodies as well as private entities during the past several years. Many of these were also obtained and searched for
materials and information relevant to the content of this report.
4.2.
The RTDF website provides PRB site summaries that briefly describe the implementation and cost of PRB installations.
These summaries typically include contact information for the sites. Contacts were attempted for all of the sites included
in this report via either telephone or email, usually both, or by visitation. Unfortunately, several of the contacts did not
respond to our inquiries, limiting information about their sites to what has been published. Those who did respond
generally provided valuable information that was unattainable via other methods.
4.3.
Detailed information acquisition forms were emailed to all site contacts. These were provided for their use in responding
to ourqueries about their PRB sites. The level of detail requested in these forms was very high and it was not anticipated
that a single site contact would have answers for all the questions that were asked. These forms were accompanied by
an explanation of the purpose of the questionnaire and the importance of the contact's information for accomplishing the
goals of this report. The contacts were also informed of our awareness that they would probably not be able to answer
all of the questions. An example of this form is found in Appendix A of this report. Although several contacts returned the
form, few of them filled it out at even the most basic level of costs (e.g., subtotals for site characterization, design,
construction, operation and maintenance). Several provided only the cost of the reactive media along with a total cost or
total construction cost. However, a few of the contacts fully completed the forms. We are grateful for the efforts of all
those who responded, especially those who attempted to fully complete the forms.
4.4.
In order to acquire more information about the PRB systems and their costs, visits were made to the University of
Waterloo and EnviroMetal Technologies, Inc. (ETI), both in Waterloo, Ontario, Canada. These entities are the patent-
holders and licensers of the PRB technology as it applies to ZVl for remediation of organic compounds and certain PRB
technologies for inorganic contaminants, such as trace metals. A great deal of site-specific information was obtained
during these visits as well as leads on additional PRB manuscripts and contacts.
4.5.
During the investigation of PRB information for this report it was often found to be very difficult to categorize cost data in
a consistent manner across sites, based upon the information obtained. Different sites often had very different
approaches to organizing their cost information and occasionally seemed to have very little information at all that could
be made public. In addition to such difficulties, we found numerous inconsistencies between reported costs and
characteristics for the same site and typographical errors in the tables and text of some documents. We have attempted
to confirm the correct values for such inconsistencies but, in a document of this kind, it is impossible to verify that all the
values used in the tables and analyses are 100% accurate. To compensate for variability in cost category reporting we
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have attempted, whenever possible, to divert site costs into categories that seemed appropriate for a comparison of this
type. We strongly urge site managers to develop standardized cost reporting techniques that allow better, more readily
comparable and accessible cost information, perhaps following the guidelines that have been recently recommended by
the Federal Remediation Technologies Roundtable (FRTR - U.S. EPA, 1998).
4.6.
The nature of this project required the acquisition and storage of large quantities of information that had to be updated as
better or more complete information was obtained. To manage this information, six custom databases were developed
using FileMaker Pro® (FileMaker, Inc.). These six included databases for (1) site information, (2) site contacts,
(3) captured information references, (4) site characterization, (5) design/construction/licensing, and (6) monitoring/O&M.
These databases were relational, with the relationships linked via the PRB site name. Many of the calculations were done
within the databases, allowing automatic updating whenever new values were entered into the databases. Scripts were
then written in FileMaker® to automatically export chosen sets of database records to Edition files. Microsoft Excel®
(Microsoft, Inc.) was then "subscribed" to these Editions, and was automatically updated whenever new data were
entered into the databases and the exporting scripts run. Tables and graphs were generated within ExcePand imported
into Microsoft Word® as linked objects for the final output. This approach speeded data throughput and should have
minimized typographical errors since data were entered, almost exclusively, into FileMaker Pro® and carried all the way
through to the final tables and charts as described.
4.7.
Although an attempt was made to determine PRB costs to a greater level of detail, practical considerations required that,
in general, costs be subtotaled into four major cost categories whenever possible. These categories are site
characterization, design, construction, and O&M (to include monitoring costs). In addition to these categories, the tables
in this report include stated costs and the approximate cost to establish the PRB and operate it during its first year. An
attempt was made to acquire PRB licensing costs but these were confidential or unobtainable for most of the sites. The
rule-of-thumb for the licensing cost is 15% of the cost of reactive media and construction for the University of Waterloo
technologies (John Vogan, ETl, personal communication). This can vary due to several factors, including PRB size.
Costs for P&T systems were not broken down into categories beyond total cost and annual O&M cost. This information
is available elsewhere and a reiteration was neither desired nor necessary for purposes of this document. An attempt
was made, however, to ascertain which of the PRB sites (a) had P&T systems installed either previously or concurrently
or (b) had estimated P&T costs as part of the remedial feasibility studies. Of the 22 sites included in this report, two have
had onsite P&T systems and seven have had P&T estimates made at the sites.
5. Economic for the
5.1, for
Stated costs for 21 of the 22 PRB sites discussed in this document are provided in Table 2. The "Stated Costs" are the
costs that have been typically reported to the public via web sites, reports, presentations and manuscripts. Stated costs
for 15 of the sites are from the publication "Field Applications of In Situ Remediation Technologies: Permeable Reactive
Barriers" (U.S. EPA, 1999b) and the corresponding RTDF web site (http://www.rtdf.org). These are referred to in Table 2,
simply as RTDF. The sources forthe stated costs forthe remaining sites, when available, are also referenced in Table 2.
In addition to stated costs, a "Calculated Approximate 1 * Year Cost" was developed for this report. This cost includes, to
our ability to determine and/or obtain them, the costs of all PRB-related activities required to get the system into the
ground and operate it for its first year. To obtain the approximate 1st year cost the following cost categories were
summed:
1. Site characterization costs
2. Design costs
3. Construction costs
4. Initial license and report fees
5. Monitoring equipment costs
6. Annual monitoring costs
7. Annual reporting costs
8. Costs of monitoring wells added for the PRB
9. Other initial monitoring/sampling costs
10. Other annual O&M costs
-------
2.
PRB Stated Costs and Sources
Site
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing, Fairfield, NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
Stated Cost Source
RTDF
RTDF
RTDF
RTDF
O'Hannesin, 1998
RTDF
RTDF
RTDF
RTDF
RTDF
RTDF
RTDF
RTDF
RTDF
RTDF
RTDF
Gavaskar et al., 2000
Personal Comm.
Heneman et al., 2000
NA
U.S. DOD, 1999
Gavaskar et al., 2000
Stated
PRB Cost
$ 500,000
$ 1,000,000
$ 387,000
$ 540,000
$ 2,100,000
$ 800,000
$ 1,500,000
$ 600,000
$ 1,120,000
$
$
$
$
875,000
400,000
797,000
400,000
$ 30,000
$
$
$
$
$
809,000
160,000
300,000
25,000
2,350,000
$
$
$
4,910,942
947,000
It should be noted that values for many of these cost categories were not available for several of the sites, therefore the
1 * year value Is the sum of fewer of these categories. In many cases, the overall cost is still the same or very close,
because the sites simply did not break down costs into subcategories. For example, some sites included characterization
in the design costs or the design costs in the construction category.
Tables provides the stated cost, the calculated approximate 1st year cost, the difference between the two, the calculated
construction cost (calculated from data obtained) and the difference between the stated cost and the construction cost.
The data for stated cost, 1 =* year cost and construction cost, are graphically depicted in Figure 1. For some sites, 1st year
cost amounted to a significantly higher dollar amount than the stated cost for the PRB site. In a few of these instances,
these stated costs were closer to the values for "Calculated Construction Cost" (discussed in a later section of this report)
which would exclude many of the other PRB costs. This illustrates that caution is warranted when stated costs are
accepted unequivocally without regard to what is included in these costs. This further supports the need for standardized
cost reporting techniques (FRTR - U.S. EPA, 1998).
Forthree of the sites we were simply unable to obtain any cost breakdown data and have only the stated costs available.
These sites were:
1. Caldwell Trucking, New Jersey
2. Massachusetts Military Reservation, CS-10 Plume, Massachusetts
3. Vancouver, Canada
5.2.
The site characterization database and the information request form contained entries for ten categories of site
characterization costs. However, site characterization costs seemed to be the most poorly tracked cost information
across the studied sites. Of the 11 sites for which a total site characterization cost was obtained, only three reported any
breakdown and these reported only one site characterization category besides "other." Therefore, no table of site
characterization breakdowns is included in this report.
5.3.
Five categories of PRB design costs were sought for this study. These were:
1. Tests, data, and statistical analysis costs
2. Modeling costs
-------
Table 3. Calculated PRB Costs Relative to Stated PRB Costs
Site
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing, Fairtleld, NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
Stated PRB
Cost
$ 500,000
$ 1,000,000
$ 387,000
$ 540,000
$ 2,100,000
$ 800,000
$ 1,500,000
$ 600,000
$ 1,120,000
$ 875,000
$ 400,000
$ 797,000
$ 400,000
$ 30,000
$ 809,000
$ 160,000
$ 300,000
$ 25,000
$ 2,350,000
$
$ 4,910,942
$ 947,000
Calculated
Approximate
1stYr. Cost
$ 1,070,000
$ 1,005,000
$ 387,000
$ 742,375
$ 2,515,000
$ 739,000
$ 1 ,490,000
$ 1,135,000
$
$ 900,000
$ 400,000
$ 1 ,000,000
$ 400,000
$ 120,000
$ 760,150
$
$ 1 ,250,000
$
$ 2,350,000
$ 29,700
$ 4,983,220
$ 1 ,095,000
Stated Cost
Minus 1st
Yr. Cost
$ (570,000)
$ (5,000)
$
$ (202,375)
$ (415,000)
$ 61,000
$ 10,000
$ (535,000)
$ (25,000)
$
$ (203,000)
$
$ (90,000)
$ 48,850
$ (950,000)
$
$ (72,278)
$ (148,000)
Calculated
Construction
Cost
$ 500,000
$ 656,000
$ 274,000
$ 377,375
$ 2,100,000
$ 358,000
$ 1,240,000
$ 700,000
$
$ 725,000
$ 400,000
$ 1,000,000
$ 356,000
$ 35,000
$ 729,250
$
$ 550,000
$
$ 2,350,000
$ 26,700
$ 4,618,122
$ 582,000
Stated Cost
Minus
Construction
$0
$344,000
$113,000
$162,625
$0
$442,000
$260,000
($100,000)
-
$150,000
$0
($203,000)
$44,000
($5,000)
$79,750
-
($250,000)
-
$0
-
$292,820
$365,000
$0
USCG Support Center
Watervliet Arsenal
Somersworth Landfill SF Site
Kansas City Plant, MO
Caldwell Trucking, NJ
Industrial Site, Coffeyville, KS
Industrial Site, SC
Cape Canaveral, FL
Pease AFB, NH
Warren AFB Spill Site 7, WY
Moffett, Full-Scale Est.
Cost
$1,000,000 $2,000,000 $3,000,000 $4,000,000 $5,000,000
• Stated PRB Cost
D Calculated Approximate 1stYr. Cost
D Calculated Construction Cost
Figure 1.
Bar plot of Stated Cost, Calculated Approximate 1st Year Cost, and Calculated Construction Cost for the
PRB sites.
-------
3. Alternatives comparison costs
4. Design plans/architectural drawing costs
5. Other design costs
In the design section of the database, the "other" field was used to contain data listed by the sites as "other design costs"
as well as for containerizing the "total design cost" when that was all that was reported. The "Design Total" field provided
the summation of all the other categories including "other." This approach was also used in the other sections of the
databases. Design costs were obtained, or calculated, for 14 of the 22 sites in this study, although only eight of them had
information broken down into one or more specific categories besides "other." Table 4 provides information on the design
cost breakdown for the PRB sites. Figures 2 and 3 show the percentage breakdown for design costs from the two sites
having data in multiple categories, USCG Support Center, North Carolina, and Somersworth Landfill, New Hampshire,
respectively.
5.4. PRB
Construction costs were sought for the sites in ten categories. These were:
1. Reactive media costs
2. Funnel costs
3. Gate costs
4. Trenching costs
5. Mobilization costs
6. Equipment costs
7. Health and safety costs
8. Installation/labor costs
9. Materials disposal costs
10. Other construction costs
Some level of construction cost breakdown was obtained for 13 of the 22 sites. Table 5 provides this information. Eleven
of the sites have data in two or more construction categories beyond "other."
Table 4. Design Cost Breakdown for the PRB Sites
Site
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing, Fairfield, NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
Tests/Stats
$ 25,000
$
$
$ 75,000
$ 100,000
$ 100,000
$
$
$
$
$
$
-
$ 30,000
$ 30,900
$
$
$
$
$
$ 75,000
$ 50,000
Modeling
$ 10,000
$
$
$
$ 40,000
$
-
$ 15,000
$
$
$
$
$
$
$
$
$
$
$
$
$
$
Alternatives
Comparison
$
$
$
$
$ 100,000
$
-
$ 10,000
$
$
$
$
$
$
$
$
$
$
$
$
$
$
Plans/
Drawings
$ 35,000
$ 100,000
$
$
$ 100,000
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$ 100,000
$
Other
$ 75,000
$ 154,000
$ 113,000
$ 100,000
-
$ 100,000
$ 100,000
$ 10,000
-
$ 150,000
$
$
$ 44,000
$
$
$
$ 200,000
$
$
$
-
$ 100,000
Design
Total
$ 145,000
$ 254,000
$ 113,000
$ 175,000
$ 340,000
$ 200,000
$ 100,000
$ 35,000
-
$ 150,000
$
$
$ 44,000
$ 30,000
$ 30,900
$
$ 200,000
$
$
$
$ 175,000
$ 150,000
-------
USCG Support Center
Design Total = $145,000
HI Tests/Stats
D Modeling
D Alternatives Comparison
D Plans/ Drawings
m Other
17%
52%
24%
Figure 2. PRB design cost breakdown for USCG Support Center, North Carolina.
Somersworth Landfill SF Site
Design Total = $340,000
29%
II Tests/Stats
D Modeling
D Alternatives Comparison
D Plans/ Drawings
30%
12%
29%
Figure 3. PRB design cost breakdown for Somersworth Landfill, New Hampshire.
-------
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-------
5.5, component summaries
Table 6 summarizes and totals the cost categories of site characterization, design, and construction for the PRB sites.
Figure 4 illustrates these major cost components for sites with data in more than one category. In terms of true "capital
costs," per our understanding of Federal Remediation Technologies Guidelines (FRTR - U.S. EPA, 1998), the capital
cost would exclude site characterization but would include licensing fees for the technology and reports to, and
interactions with, regulatory agencies. Table 7 includes these costs, for the few sites where the data could be obtained,
along with the design, construction, and total capital cost summation. It should be noted that the capital costs in Table 7,
and displayed graphically in Figure 5, are calculated from the design and construction costs which are themselves
calculated from cost subcategories detailed in Tables 4 (design) and 5 (construction). Because of this there are no capital
cost entries for the three sites for which cost breakdowns could not be obtained. It is possible that the "Stated Costs" for
these sites are equivalent to the capital costs but, in the absence of additional information, these were not included in the
table.
5.6. at the
Annual operation and maintenance (O&M) costs were calculated or obtained from 10 of the 22 sites. O&M cost
categories included:
1. Annual monitoring costs
2. Annual reporting costs
3. Other annual O&M costs
In addition to these annual costs, it is anticipated that the reactive media may require periodic replenishment or
replacement in these PRB systems. Recent speculation has suggested periods of five to 10 years for the replenishment/
replacement cycle during a 30-year lifetime. When the reactive media is iron metal, this cycle may be at about 10-year
intervals, although this could vary based upon ground-water chemistry and other site factors. The interval for replacing
organic matter-based PRBs may be shorter, based upon recent results from the Nickel Rim site in Ontario (D. Blowes,
personal communication). Because of reactive media maintenance or replacement, the annual O&M cost for PRBs might
have a periodic jump relative to the routine annual O&M costs. This cost should be figured into the O&M future cost
scenario when comparing PRBs to other technologies, such as P&T. Typically, PRBs will have relatively low annual
O&M, including only monitoring and reporting costs, relative to more active remediation technologies. This is due to the
passive nature of most PRB installations that rely on the natural hydraulic gradient of the ground water to move the
contaminants through the reaction zone. P&T systems, on the other hand, are comprised of a number of actively working
components, including pumps, valves, treatment trains, etc., that require ongoing maintenance, parts replacement, etc.
Because most PRB sites have been in the ground for less than five years, media maintenance costs remain a matter of
great speculation. Research is ongoing to determine means of replenishing the media in situ, rather than fully replacing
the media. Column and field investigations on iron-media PRBs have shown that the upgradient surface of the reactive
zone is the most likely region for failure to occur, a direct result of the ongoing remedial reactions. If failure occurs it will
probably be due to the formation of precipitates on the iron surfaces and in the voids between the iron granules. These
precipitates can both lower the reactivity of the iron and reduce ground-water flow through the PRB. Since these
depleted/altered/precipitated regions seem to extend for only a few centimeters into the PRB, at sites currently studied,
the most likely mode for failure is flow blockage. This could cause diversion of contaminated waters over, under and
around the PRB, reducing its remedial effect. These effects have been graphically illustrated and described (Powell et al.,
1998). However, recent geochemical modeling studies, using site ground-water characteristics, have indicated only
about 15% porosity reduction over a lifetime of 20 years (J. Vogan, personal communication; RTDF PRB Workshop).
Should this prove accurate then, theoretically, iron maintenance might not be necessary over a 30 year PRB lifetime for
some systems.
Various techniques are being proposed for replenishing and/or disrupting precipitate-cemented PRB surfaces in situ (M.
Duchene, ETI, personal communication). Among these are:
1. Jetting the upgradient face of the PRB with water under high pressure;
2. Using solid-stem augers to agitate the upgradient face of the PRB;
3. Using ultrasound to break-up the precipitate on the upgradient face; and
4. Using a pressure wave hydraulic pulse method to break-up the precipitate.
These methods hope to avoid the actual replacement of the media that, in most cases, would be much more expensive.
With the exception of ultrasound, field trials of these possible rejuvenation methods have not been completed and it can
only be stated that these methods may prove to be successful.
11
-------
Table 6. Major Cost Components for the PRB Sites
Site
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing, Fairfield, NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
Site
Characterization
$ 150,000
$
$
$ 100,000
$
$ 165,000
$ 150,000
$ 350,000
$
$
$
$
$
$ 25,000
$
-
$ 400,000
$
$
-
$ 117,820
$ 215,000
Design
$ 145,000
$ 254,000
$ 113,000
$ 175,000
$ 340,000
$ 200,000
$ 100,000
$ 35,000
$
$ 150,000
$
$
$ 44,000
$ 30,000
$ 30,900
-
$ 200,000
$
$
-
$ 175,000
$ 150,000
Construction
$ 500,000
$ 638,000
$ 257,000
$ 332,375
$ 2,100,000
$ 296,000
$ 1,200,000
$ 700,000
$
$ 725,000
$ 400,000
$ 1,000,000
$ 356,000
$ 35,000
$ 729,250
-
$ 500,000
-
$ 2,200,000
$ 23,700
$ 4,572,122
$ 520,000
Total
$ 795,000
$ 892,000
$ 370,000
$ 607,375
$ 2,440,000
$ 661 ,000
$ 1,450,000
$ 1,085,000
$
$ 875,000
$ 400,000
$ 1,000,000
$ 400,000
$ 90,000
$ 760,150
-
$ 1,100,000
-
$ 2,200,000
$ 23,700
$ 4,864,942
$ 885,000
Cost
$0
$1,000,000
$2,000,000
$3,000,000
$4,000,000
$5,000,000
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SFSite
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Former Manufacturing, Fairfield, NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
Pease AFB, NH
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
=
• Site Characterization
n Design
D Construction
Figure 4. Major cost components for the PRB sites.
12
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Table 7. PRB Site Capita! Cost Summary
Site
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing, Fairfield, NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
Design
$ 145,000
$ 254,000
$ 113,000
$ 175,000
$ 340,000
$ 200,000
$ 100,000
$ 35,000
$
$ 150,000
$
$
$ 44,000
$ 30,000
$ 30,900
$
$ 200,000
$
$
$
$ 175,000
$ 150,000
Construction
$ 500,000
$ 638,000
$ 257,000
$ 332,375
$ 2,100,000
$ 296,000
$ 1,200,000
$ 700,000
$
$ 725,000
$ 400,000
$ 1,000,000
$ 356,000
$ 35,000
$ 729,250
$
$ 500,000
$
$ 2,200,000
$ 23,700
$ 4,572,122
$ 520,000
PRB
License
$
$
$ 17,000
$
$
$
$
$
$
$
$
$
$
$
$
$
$ 50,000
$
$ 150,000
$ 3,000
$
$
Initial
Reporting
$ 190,000
$
$
$
$ 75,000
$
-
$
$
-
$
$
$
$
$
$
$
$
$
-
$
$
Capital Cost
Total
$ 835,000
$ 892,000
$ 387,000
$ 507,375
$ 2,515,000
$ 496,000
$ 1,300,000
$ 735,000
$
$ 875,000
$ 400,000
$ 1,000,000
$ 400,000
$ 65,000
$ 760,150
$
$ 750,000
$
$ 2,350,000
$ 26,700
$ 4,747,122
$ 670,000
Capital Cost
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing, Fairfield, NJ
Industrial Site, Coffeyville, KS
Sites
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMR CS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
Figure 5. Capital costs of the PRB sites.
0 $1,000,000 $2,000,000 $3,000,000 $4,000,000 $5,00(
I
|
^=1
|
I
I
I
D
i
i
1
i
|
1
1
13
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We were able to obtain stated media maintenance estimates for only three of the 22 sites in this study. One of these is
a functioning PRB site (Intersil) while the other two are estimates for the proposed full-scale implementations at Dover
AFB and Moffett Federal Airfield, However, until recently, EnviroMetal Technologies had proposed that, in general,
rejuvenation techniques can be evaluated based on a percentage of the original cost of iron metal media (U.S. EPA,
1998). These percentages are 30% for the continuous trench configuration and 20% for the funnel and gate (lower due
to its relatively shorter total length; i.e., less face surface area exposure). These O&M and replace/replenish costs are
provided in Table 8. It is noted that, of the three sites with estimated replenishment/replacement costs, all are significantly
higher than the ETI calculation estimates. However, it is uncertain to us how these estimates have been calculated. It is
also noteworthy that the maintenance estimates for the three sites vary widely with respect to their percentage of the
original construction costs. These percentages are 35% for Intersil, 5% for Moffett full-scale, and 72% for Dover full-
scale. More recently, ETI has estimated O&M using unit costs that are dependent on which of the four rejuvenation
techniques is being considered (John Vogan, Mike Duchene, personal communication). In terms of dollars per square
foot, these are $3-$15 for jetting, $5-$15 using agitation with solid-stem augers, and $15-$20 for either ultrasound or
pressure pulse technology. The ranges in cost tend to depend upon the target depth, auger diameter, etc. These
estimates are also included in Table 8, using the cost midpoint for each technique (i.e., $9, $10, and $17.50 per square
foot, respectively). Mobilization costs must also be considered and are not included in these cost estimates. ETI notes
that both the ultrasound and the pressure pulse technologies offer certain advantages that might offset their higher costs
relative to jetting and mechanical agitation. These are:
1. Both use tools that can be placed in conventional two to four inch diameter wells.
2. Both avoid significant spoils generation during use.
3. Both technologies may be used proactively as a form of routine O&M to minimize issues of hydraulic
blockage and loss of reactivity before these problems become significant.
It is likely that the actual costs for media maintenance activities will remain largely unknown until some fraction of the
PRB sites have begun to fail and undergone a rejuvenation process. It seems reasonable to assume that the longer and
deeper the reactive media zones (i.e., higher in media upgradientface, or frontal boundary surface area) the more it will
cost to treat/replace the reactive media. Extremely large-scale continuous trench PRBs will probably not fare well in the
context of per maintenance cost with F&G configurations. This is because the reactive media itself comprises the entire
frontal surface area of the continuous PRB. This will require one of the five replenishment techniques (above) to be
carried out along the entire length of the PRB. In the F&G system, only the gate surface areas are exposed, with the
gates compensating for the extra needed reactivity by having thicker reaction zones. This results in a much lower length
of treatment at the frontal boundary. However, frequency of needed maintenance may be increased with the F&G
systems. Whereas continuous trench systems have ground-water flow through them at approximately the natural flow
conditions of the aquifer, the F&G systems have greatly increased the flux through the gates by capturing additional
water with the funnel sections. Therefore, F&G systems are treating more water per unit time than the continuous
trenches, possibly also increasing the rate of precipitate buildup on the frontal boundary of the media. This could lead to
an increase in the necessary frequency of maintenance.
Table 9 provides information for the 22 PRB sites in this study with regard to factors that could impact the cost of
maintenance. The total lengths, approximate average depths, and calculated cross-sectional surface areas of the
systems are provided, as are the same values for the reactive media zones. In the case of continuous trench PRBs these
values are, of course, equal. Table 9 also has a column displaying the ratio of the reactive media cross-sectional surface
area (Media SA)1 to that of the entire PRB system (PRB SA). Fora standard continuous trench, the ratio is one, whereas
the values range from 0.007 to 0.6 for the F&G systems2. Although other factors would also affect maintenance costs, it
seems reasonable that, for a continuous trench system of the same size as a F&G system, this ratio might be somewhat
useful in estimating periodic media maintenance costs. For example, one could compare the Dover full-scale estimate for
a F&G system to a hypothetical continuous trench having exactly the same dimensions. These would be 136ft long by
39ft deep, resulting in a frontal surface area of 5304ft2 for the continuous trench. However, the four4ft-wide gates, also
constructed to a depth of 39ft, have a surface area of only 624ft2. The ratio between these two values is 0.118, as shown
in Table 9. Assuming the cost of surface jetting (for example) the gates is equivalent to 1, the cost of jetting a continuous
trench PRB of the same dimensions could be 1/0.118 or 8.5 times the cost, although the trench should need to be
serviced proportionally less frequently.
' Note: This refers to the geometric surface area of the system, i.e., the total facial area of the media and does not include any
calculation of the actual surface area of the media granules. That is, the Media SA includes both the frontal surface area occupied
by the media granules as well as that of the void spaces between them.
2 Values in Table 9 higher than 1 are for continuous trench PRB systems that have "polishing" PRB trenches downgradient from the
initial PRB. These following trenches were not included in the total PRB capture length because their length was encompassed by
the length of the upgradient primary PRB.
14
-------
Tables. O&M Costs for the PRB Sites
Site
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF
Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance,
OR
Caldwell Trucking, NJ
Former Manufacturing,
Fairfield, NJ
Industrial Site,
Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7,
WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale
Est.
Annual PRB
O&M
$ 85,000
$ 95,000
$
$ 90,000
$
$
$
$ 50,000
$
$ 25,000
$
$
$
$ 30,000
$
$
$ 35,000
$
$
$ 3,000
$ 72,278
$ 148,000
PRB Stated
Fe
Maintenance
$
$ 232,000
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$
$ 267,538
$ 421,000
ETI Original
Fe
Maintenance
Calc.
$ 60,000
$ 34,000
$ 26,208
$ 7,875
$ 360,000
$ 9,400
$
$
$
$ 107,700
$
$
$
$ 4,500
$
$
$
$
$
$ 2,400
$ 176,260
$ 9,600
ETI Jetting Fe
Maintenance
Calc.
$ 32,832
$ 4,536
$ 25,200
$ 2,250
$ 288,000
$ 2,808
$ 35,100
$ 26,100
$ 81,000
$ 28,575
$ 1,980
$ 59,940
$ 84,825
$ 6,300
$ 56,700
$ 43,200
$ 44,550
$ 5,643
$ 76,680
$
$ 63,180
$ 5,616
ETI Auger
Agitation Fe
Maintenance
Calc.
$ 36,480
$ 5,040
$ 28,000
$ 2,500
$ 320,000
$ 3,120
$ 39,000
$ 29,000
$ 90,000
$ 31 ,750
$ 2,200
$ 66,600
$ 94,250
$ 7,000
$ 63,000
$ 48,000
$ 49,500
$ 6,270
$ 85,200
$
$ 70,200
$ 6,240
ETI Ultrasound
or Pressure Fe
Maintenance
Calc.
$ 63,840
$ 8,820
$ 49,000
$ 4,375
$ 560,000
$ 5,460
$ 68,250
$ 50,750
$ 157,500
$ 55,563
$ 3,850
$ 116,550
$ 164,938
$ 12,250
$ 110,250
$ 84,000
$ 86,625
$ 10,973
$ 149,100
$
$ 122,850
$ 10,920
6. Economic for the Pump-and-Treat
6.1.
Nine of these 22 PRB sites have either had active P&T systems at the site or some aspect of P&T cost estimates made
for the site. This information, as well as available construction and O&M cost information, is provided in Table 10. A "0"
in the "On-Site P&T" column indicates that the information was not relevant to the pilot-scale because a full-scale
estimate was made for both types of systems (Moffett Federal Airfield and Dover AFB). ND in this field means that no
data were available. It should be noted that the Somersworth P&T system estimate is extremely high in cost. This cost
is from the record of decision (ROD) for the site and due in large part to the planned construction of a slurry wall and an
impermeable cap over the site. The ROD amendment now calls for a PRB and a permeable cap, at a total cost of
approximately $7,000,000. Due to this, a comparison of Somersworth PRB versus P&T costs is not valid because we
have been unable to locate cost data for the P&T excluding the cap.
Table 11 provides a side-by-side comparison of P&T versus PRB construction and O&M costs, including differences in
the values (P&T minus PRB). Figure 6 depicts the comparison of the construction costs and Figure 7 the O&M costs. In
four of the five valid comparisons (excluding Somersworth Landfill) the PRB system is more expensive to construct than
the P&T system and the reverse is true for the remaining site (Watervliet). Whether or not P&T construction will be more
or less expensive than a PRB system will be highly site specific. In the of annual O&M, however, the P&T systems
are significantly more expensive than the PRB systems in all five of the valid comparisons.
6.2. P&T at
Although not addressed in detail in this report, P&T data from other sites can illustrate the importance of using
comparable unit cost values when evaluating the potential cost-effectiveness of PRB versus P&T installations. This is
addressed in Section 7.1 and illustrated in Section 7.3.
15
-------
Table 9.
PRB Information Relevant to Maintenance Costs
Site
USCG Support
Center
Intersil Site
Watervliet Arsenal
Moffett Federal
Airfield
Somersworth
Landfill SF Site
Dover AFB, DE
Kansas City Plant,
MO
Aircraft
Maintenance, OR
Caldwell Trucking,
NJ
Former
Manufacturing,
Fairfield, NJ
Industrial Site,
Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim,
Ontario
Cape Canaveral,
FL
MMRCS-10
Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill
Site 7, WY
London, Ontario
Moffett, Full-Scale
Est.
Dover, AFB Full-
Scale Est.
Reactive
Material
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Fe(0)
Organic
Matter
Fe(0)
Fe(0)
Fe(0)
Organic
Matter
Fe(0)
Oxygen
furnace
slag
Fe(0)
Fe(0)
Mass,
Tons
450
220
165.5
75
3552
59
650
324
250
720
70
742
400
425
205
49
360
0
1750
400
2518
108
PRB Type
Trench
F&G
Trench
F&G
Trench
F&G
Trench
F&G
Hydr.
Frac./Per
m. Infill
Trench
F&G
Trench
Trench
Trench
Trench
Hydr.
Frac./Per
m. Infill
Trench
Trench
Trench
Trench
F&G
F&G
Reactive
Media Cost
$ 200,000.00
$ 170,000.00
$ 87,360.00
$ 39,375.00
$ 1,200,000.00
$ 47,000.00
$
$
$
$ 359,000.00
$ 50,000.00
$ 358,000.00
$ 133,000.00
$ 15,000.00
$
$
-
$
$ 600,000.00
$ 8,000.00
$ 881,300.00
$ 48,000.00
Total
PRB
Length,
ft
152
40
190
50
800
68
130
650
180
127
1020
370
325
50
100
48
150
33
568
0
1100
136
Ave.
PRB
Depth,
ft
24
20
10
25
40
39
30
29
50
25
30
18
29
14
45
100
33
19
15
0
45
39
Total
PRB
Surface
Area,
ftA2
3648
800
1900
1250
32000
2652
3900
18850
9000
3175
30600
6660
9425
700
4500
4800
4950
627
8520
0
49500
5304
Total
Reactive
Media
Length,
ft
152
36
280
10
800
8
130
100
180
127
20
370
325
50
140
48
150
33
568
0
135
16
Ave.
Reactive
Media
Depth, ft
24
14
10
25
40
39
30
29
50
25
11
18
29
14
45
100
33
19
15
0
52
39
Reactive
Media
Face
Surface
Area,
ftA2
3648
504
2800
250
32000
312
3900
2900
9000
3175
220
6660
9425
700
6300
4800
4950
627
8520
0
7020
624
Ratio,
Media
SA to
PRBSA
1.000
0.630
1.474
0.200
1.000
0.118
1.000
0.154
1.000
1.000
0.007
1.000
1.000
1.000
1.400
1.000
1.000
1.000
1.000
NA
0.142
0.118
16
-------
Table 10. P&T Information for the PRB Sites
Site
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing,
Fairfield, NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
On-Site P&T
Estimated
Yes
Estimated
0
Estimated
0
Yes
No
ND
Estimated
ND
Estimated
ND
No
ND
ND
ND
ND
ND
ND
Estimated
Estimated
P&T
Construction
Cost
$ 500,000
$ 325,000
$ 834,000
$
$ 26,000,000
$
$
$
$
$ 350,000
$
$
$
$
$
$
$
-
$
$
$ 1,400,000
$ 502,000
Annual P&T
O&M
$ 200,000
$ 142,158
$
$
$ 3,400,000
$
$ 200,000
$
$
$ 98,000
$
$ 300,000
$
$
$
$
$
-
$
$
$ 695,000
$ 219,833
Table 11. Comparison of P&T Costs Versus PRB Costs
Site
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing,
Fairfield, NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
P&T
Construction
Cost
$ 500,000
$ 325,000
$ 834,000
$
$ 26,000,000
-
$
$
$
$ 350,000
$
$
$
$
$
$
$
$
$
$
$ 1,400,000
$ 502,000
Calc. PRB
Construction
Cost
$ 500,000
$ 656,000
$ 274,000
$ 377,375
$ 2,100,000
$ 358,000
$ 1,240,000
$ 700,000
$
$ 725,000
$ 400,000
$ 1,000,000
$ 356,000
$ 35,000
$ 729,250
$
$ 550,000
$
$ 2,350,000
$ 26,700
$ 4,618,122
$ 582,000
P&T
Construction
Minus PRB
Construction
$
$ (331 ,000)
$ 560,000
$
$ 23,900,000
$
$
$
$
$ (375,000)
$
$
$
$
$
$
$
$
$
$
$ (3,218,122)
$ (80,000)
Annual P&T
O&M
$ 200,000
$ 142,158
$
$
$ 3,400,000
$
$ 200,000
$
$
$ 98,000
$
$ 300,000
$
$
$
$
$
$
$
$
$ 695,000
$ 219,833
Annual PRB
O&M
$ 85,000
$ 95,000
$
$ 90,000
$
$
$
$ 50,000
$
$ 25,000
$
$
$
$ 30,000
$
$
$ 35,000
$
$
$ 3,000
$ 72,278
$ 148,000
Annual P&T
Minus PRB
O&M
$ 115,000
$ 47,158
$
$
$
$
$
$
$
$ 73,000
$
$
$
$
$
$
$
$
$
$
$ 622,722
$ 71,833
17
-------
$0
$1,000,000
Construction Cost
$2,000,000 $3,000,000 $4,000,000 $5,000,000
tfi
(
USCG Support Center
Intersil Site
Watervllet Arsenal
Moffett Federal Airfield
Somersworth Landfill SFSite
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing, Fairfield, NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
I
^r"
— i
$26,000,000.0
1 Somersworth P&T cost includes large-scale impermeable cap
^^^^^^j
^=*
!
I
*
aCalc. PRB Construction Cost
D P&T Construction Cost
Figure 6. PRB construction costs versus P&T construction costs at the PRB sites.
$o
$250,000
Cost
$500,000
$750,000
$1,000,000
tfi
(
USCG Support Center
Intersil Site
Watervl let Arsenal
Moffett Federal Airfield
Somersworth Landfill SFSite
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing, Fairfield, NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
$3,400,000
BAnnual P&TO&M
rjAnnual PRB O&M
Figure 7. PRB O&M costs versus P&T O&M costs at the PRB sites.
18
-------
7. Cost Comparison of PRB versus P&T Technologies
7. f.
As mentioned in Section 2, reports have been published that seem to indicate that PRB systems are no more effective
for reducing operation and maintenance costs, on a per unit of treatment basis, than P&T systems. These reports are
comparing the technologies based on volume of water treated per unit time. We have examined these reports and data
and determined that the method of comparison is causing the discrepancy between low anticipated PRB unit costs and
those being reported. The same reports which show a very high O&M unit cost for PRB systems also show extremely low
average annual O&M costs for the PRB sites when not expressed as unit costs. Unit costs in these reports were
expressed in dollars per 1000 gallons of treated water. This was without regard to whether all the water passing through
the P&T systems even needed to be treated. In fact, one of the known problems with P&T systems is that they extract
large quantities of ground water for treatment whether it is contaminated or not, often mixing the two as the water is
withdrawn from the aquifer. The ratio of contaminated to uncontaminated water entering the P&T system depends on
several factors, including the location of the pumping well(s), the rate of pumping, and the time frame during which the
system has been operational3.
Using a unit cost of "dollars per 1000 gallons treated per year" will always skew in favor of the treatment that processes
the most water. If a P&T system costs exactly the same as a PRB system (both capital and O&M costs), it will always
yield a lower unit cost ($71000 gal) if its pumping rate exceeds the natural flux rate of water through the PRB. The PRB
system, of course, typically depends upon the natural gradient for its contaminated water input. In this report, it is our
contention that the excess water treated by a P&T should not be considered when comparing the costs of P&T relative
to a PRB. A more logical comparison would be to assume that the PRB system is properly designed and capturing the
entire contaminant plume, thus protecting downgradient receptors. One can then use only the annual number of gallons
passing through the PRB as the number of gallons that should be treated by either the PRB or the P&T systems. Any
additional water treated by the P&T system is superfluous and should not be factored into the calculations. As an
illustration:
Assume a P&T system costs $500,000 in O&M per year. Compare it to a PRB that costs $100,000 in
O&M per year. The P&T system treats 1 million gallons per year (gpy), whereas the PRB passes and
treats only 100,000 gpy, or 1/10 the volume. Based on the way these figures are currently being
calculated in other reports, the P&T would cost only $500/1000 gallons whereas the PRB comes in at
$1000/1000 gallons, or twice the cost. However, the PRB is capturing all the water that needs to be
treated and the excess water treated by the P&T is simply wasted effort. Therefore, the P&T value
should be calculated using the same volume of water that is treated by the PRB; i.e., 100,000 gallons
per year. This results in the P&T having an O&M cost of $5000/1000 gallons of actual contaminated
water, a factor of five more expensive than the PRB.
Comparing unit costs of PRB versus P&T systems by using the annual volume passing through the PRB at a given site
is the approach that has been used in this document.
7.2. per of
In order to compare PRB cost with P&T cost we have estimated flow through the PRB systems using data obtained from
publications and contacts. To accomplish this we have made a few assumptions regarding the PRB systems:
1. A continuous trench captures water at the natural ground-water velocity over its entire saturated (i.e., below
the water table) cross-sectional surface area.
2. An F&G system also captures and passes all the water impinging its entire submerged surface area,
including both funnels and gates, passing it through the gates.
3. The PRB systems are properly designed and constructed, hence capturing the entire cross-sectional area of
the plume as it migrates.
4. The total volume of water that needs to be treated per unit time is the amount that passes through the PRB
per unit time.
5. Radionuclides are not being treated.
3 During the lifetime of a P&T system, contaminants are usually readily removed at high concentrations during the early period of
operation. As time passes, the concentrations of the removed contaminants decline, their ultimate removal being limited by slow
desorption and dissolution phenomena. This means that while some contamination is still being removed, much more uncontami-
nated water is being drawn into the system and being treated as though contaminated (which it has become during the mixing).
19
-------
Assumption 1 is reasonable, although the barrier permeability may vary from the aquifer and certain construction
procedures might impact the aquifer/PRB interface somewhat (e.g., compaction or clay smearing). Assumption 2 is not
exactly accurate since flow modeling and field studies show that water capture is incomplete near the distal ends of the
funnel sections. For an F&G system a certain amount of over-engineering is needed to ascertain that the entire plume
cross-sectional area is captured and cannot pass over (water mounding) or under the system or around its ends.
Because of these concerns, most PRBs installed during the past two years or so have been continuous systems rather
than F&G. For purposes of comparison to P&T systems, the differences in our captured volume estimates versus actual
capture are probably not very significant, especially for the large F&G systems. Assumption 3 should be valid provided
proper site characterization has been accomplished. Implicit in Assumption 4 is that the P&T systems are generally
extracting more ground water than is necessary, or even desirable, for treatment of the contaminants. Assumption 5
results because it is likely that PRBs for radioactive contaminants will have to be excavated and the materials disposed.
The cost of reactive media removal and disposal while radioactive are not assessed in this document.
Assumption 2 also results in a consideration of how much of the PRB is below the water table, plus the knowledge that
not all water impacting the funnel sections of an F&G system is moving through the gate(s). Although water level and
capture data were not available for most of the sites, in general, the ratio of capturing to non-capturing surface area
seemed to fall in the range of about 2/3. This seemed reasonable so we have assumed a "capture ratio" of 0.666 to
evaluate water volume per unit time for these comparisons.
Table 12 provides data relevant to this cost comparison exercise, including the PRB surface areas, ground-water
velocities, and annual ground-water volumes passing through the PRBs at two different capture factors. Factor 1 is the
0.666 factor mentioned above and Factor 2 is simply 1, where water capture is equivalent to the amount intercepted by
the entire surface area of the PRB. Data for 19 of the 22 sites are presented in this table. A zero value is given for the
three sites for which data were not available. Table 13 further sets up this comparison, providing the results of present
value (PV) calculations on the annual O&M costs for 10 of the 22 PRB sites at an annual inflation (discount) rate of 4%.
These values represent the cost, in terms of dollar values at the time O&M costs were stated (generally 1995 to 2000),
over a subsequent 30-year period, including a summary total.
Table 12. Ground-water Flow and Volume Data Relevant to a Unit Cost Evaluation
Site
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing, Fairfield, NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
Total PRB
Surface
Area, ftA2
3648
800
1900
1250
32000
2652
3900
18850
9000
3175
30600
6660
9425
700
4500
4800
4950
627
8520
0
49500
5304
GWFlow
Velocity,
ft/d
0.4
0.8
0.15
0.35
1.25
0.18
0.59
0.3
1.1
0.6
0.6
0.6
0.14
0.13
0.05
1
0
0
0.9
0
0.35
0.18
PRB
Capture
Factor 1
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
6.67E-01
Factor 1
GWVolume,
gal/yr
2.66E+06
1.16E+06
5.19E+05
7.96E+05
7.28E+07
8.69E+05
4.19E+06
1.03E+07
1.80E+07
3.47E+06
3.34E+07
7.27E+06
2.40E+06
1.66E+05
4.10E+05
8.74E+06
O.OOE+00
O.OOE+00
1.40E+07
O.OOE+00
3.15E+07
1.74E+06
PRB
Capture
Factor 2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Factor 2
GWVolume,
gal/yr
3.98E+06
1.75E+06
7.78E+05
1.19E+06
1.09E+08
1.30E+06
6.28E+06
1.54E+07
2.70E+07
5.20E+06
5.01E+07
1.09E+07
3.60E+06
2.48E+05
6.14E+05
1.31E+07
O.OOE+00
O.OOE+00
2.09E+07
O.OOE+00
4.73E+07
2.61 E+06
20
-------
Table 13. Present Value Calculation for Annual PRB Site O&M Costs, Including 30-year Total as Present Value
Year
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
Total 30
Yr
Annual
O&MPV
USCG Support
Center
$ 85,000.00
$ 81,730.77
$ 78,587.28
$ 75,564.69
$ 72,658.36
$ 69,863.80
$ 67,176.73
$ 64,593.01
$ 62,108.67
$ 59,719.87
$ 57,422.95
$ 55,214.38
$ 53,090.75
$ 51,048.80
$ 49,085.38
$ 47,197.48
$ 45,382.19
$ 43,636.73
$ 41,958.39
$ 40,344.61
$ 38,792.89
$ 37,300.86
$ 35,866.21
$ 34,486.74
$ 33,160.33
$ 31,884.93
$ 30,658.58
$ 29,479.41
$ 28,345.59
$ 27,255.37
$ 26,207.09
$1,554,822.83
Intersil Site
$ 95,000.00
$ 91,346.15
$ 87,832.84
$ 84,454.65
$ 81,206.40
$ 78,083.08
$ 75,079.88
$ 72,192.19
$ 69,415.57
$ 66,745.74
$ 64,178.60
$ 61,710.19
$ 59,336.72
$ 57,054.54
$ 54,860.13
$ 52,750.13
$ 50,721.28
$ 48,770.46
$ 46,894.67
$ 45,091.03
$ 43,356.76
$ 41,689.19
$ 40,085.76
$ 38,544.00
$ 37,061.54
$ 35,636.10
$ 34,265.48
$ 32,947.57
$ 31,680.36
$ 30,461.88
$ 29,290.27
$ 1,737,743.16
Moffett
Federal
Airfield
$ 90,000.00
$ 86,538.45
$ 83,210.06
$ 80,009.67
$ 76,932.38
$ 73,973.44
$ 71,128.31
$ 68,392.60
$ 65,762.12
$ 63,232.81
$ 60,800.78
$ 58,462.28
$ 56,213.73
$ 54,051.67
$ 51,972.76
$ 49,973.81
$ 48,051.74
$ 46,203.59
$ 44,426.53
$ 42,717.82
$ 41,074.83
$ 39,495.02
$ 37,975.98
$ 36,515.37
$ 35,110.93
$ 33,760.51
$ 32,462.03
$ 31,213.49
$ 30,012.97
$ 28,858.63
$ 27,748.68
$1,646,283.00
Aircraft
Maintenance,
OR
$ 50,000.00
$ 48,076.92
$ 46,227.81
$ 44,449.82
$ 42,740.21
$ 41,096.36
$ 39,515.73
$ 37,995.89
$ 36,534.51
$ 35,129.34
$ 33,778.21
$ 32,479.05
$ 31,229.85
$ 30,028.70
$ 28,873.75
$ 27,763.23
$ 26,695.41
$ 25,668.66
$ 24,681.41
$ 23,732.12
$ 22,819.35
$ 21,941.68
$ 21,097.77
$ 20,286.32
$ 19,506.07
$ 18,755.84
$ 18,034.46
$ 17,340.83
$ 16,673.87
$ 16,032.57
$ 15,415.93
$ 914,601.67
Former
Manufacturing,
Falrfleld, NJ
$ 25,000.00
$ 24,038.46
$ 23,113.91
$ 22,224.91
$ 21,370.10
$ 20,548.18
$ 19,757.86
$ 18,997.95
$ 18,267.26
$ 17,564.67
$ 16,889.10
$ 16,239.52
$ 15,614.93
$ 15,014.35
$ 14,436.88
$ 13,881.61
$ 13,347.70
$ 12,834.33
$ 12,340.70
$ 11,866.06
$ 11,409.67
$ 10,970.84
$ 10,548.88
$ 10,143.16
$ 9,753.04
$ 9,377.92
$ 9,017.23
$ 8,670.41
$ 8,336.94
$ 8,016.29
$ 7,707.97
$ 457,300.83
Nickel Rim,
Ontario
$ 30,000.00
$ 28,846.15
$ 27,736.69
$ 26,669.89
$ 25,644.13
$ 24,657.81
$ 23,709.44
$ 22,797.53
$ 21,920.71
$ 21,077.60
$ 20,266.93
$ 19,487.43
$ 18,737.91
$ 18,017.22
$ 17,324.25
$ 16,657.94
$ 16,017.25
$ 15,401.20
$ 14,808.84
$ 14,239.27
$ 13,691.61
$ 13,165.01
$ 12,658.66
$ 12,171.79
$ 11,703.64
$ 11,253.50
$ 10,820.68
$ 10,404.50
$ 10,004.32
$ 9,619.54
$ 9,249.56
$548,761.00
Pease AFB,
NH
$ 35,000.00
$ 33,653.85
$ 32,359.47
$ 31,114.87
$ 29,918.15
$ 28,767.45
$ 27,661.01
$ 26,597.12
$ 25,574.16
$ 24,590.54
$ 23,644.75
$ 22,735.33
$ 21,860.90
$ 21,020.09
$ 20,211.63
$ 19,434.26
$ 18,686.79
$ 17,968.06
$ 17,276.98
$ 16,612.48
$ 15,973.54
$ 15,359.18
$ 14,768.44
$ 14,200.42
$ 13,654.25
$ 13,129.09
$ 12,624.12
$ 12,138.58
$ 11,671.71
$ 11,222.80
$ 10,791.15
$640,221.17
London,
Ontario
$ 3,000.00
$ 2,884.62
$ 2,773.67
$ 2,666.99
$ 2,564.41
$ 2,465.78
$ 2,370.94
$ 2,279.75
$ 2,192.07
$ 2,107.76
$ 2,026.69
$ 1,948.74
$ 1,873.79
$ 1,801.72
$ 1,732.43
$ 1,665.79
$ 1,601.72
$ 1,540.12
$ 1,480.88
$ 1,423.93
$ 1,369.16
$ 1,316.50
$ 1,265.87
$ 1,217.18
$ 1,170.36
$ 1,125.35
$ 1,082.07
$ 1,040.45
$ 1,000.43
$ 961.95
$ 924.96
$ 54,876.10
Moffett, Full-
Scale Est.
$ 72,278.00
$ 69,498.08
$ 66,825.07
$ 64,254.88
$ 61,783.54
$ 59,407.25
$ 57,122.35
$ 54,925.34
$ 52,812.83
$ 50,781.56
$ 48,828.43
$ 46,950.41
$ 45,144.63
$ 43,408.29
$ 41,738.74
$ 40,133.41
$ 38,589.82
$ 37,105.59
$ 35,678.45
$ 34,306.21
$ 32,986.74
$ 31,718.02
$ 30,498.09
$ 29,325.09
$ 28,197.20
$ 27,112.69
$ 26,069.90
$ 25,067.21
$ 24,103.08
$ 23,176.04
$ 22,284.66
$1,322,111.58
Dover, AFB Full-
Scale Est.
$ 148,000.00
$ 142,307.69
$ 136,834.32
$ 131,571.46
$ 126,511.02
$ 121,645.21
$ 116,966.55
$ 112,467.84
$ 108,142.15
$ 103,982.84
$ 99,983.50
$ 96,137.98
$ 92,440.36
$ 88,884.96
$ 85,466.31
$ 82,179.15
$ 79,018.41
$ 75,979.24
$ 73,056.96
$ 70,247.08
$ 67,545.27
$ 64,947.37
$ 62,449.40
$ 60,047.50
$ 57,737.98
$ 55,517.29
$ 53,382.01
$ 51,328.85
$ 49,354.67
$ 47,456.41
$ 45,631.16
$ 2,707,220.93
PV costs indicate the amount of money that would have to be set aside today to fully cover the costs of a technology in
the present and the future (Gavaskar et al., 2000). The equation used is:
PV = Capital Investment + PV
" annu;
(1)
The capital cost is incurred in the present, whereas the PV.
PVannual costs 'SCalCUlatedaS
annual costs
occurs both in the present and in the future. The
PV
annual costs '
Y
(2)
where: i is the year
Y is the year i cost
year i = 0 is the construction/startup year (capital investment year)
years i = 1 through n are the operation and maintenance years
n = total years of operation
r = discount rate
Table 13 carries out the year by year calculation of Equation 2 for the O&M costs of the PRB sites assuming an annual
inflation rate of 4% included as the discount rate, r.
21
-------
The total O&M PV costs are carried into Table 14forthe eight PRB sites where we have sufficient data to calculate costs
per 1000 gallons of treated water. The upper part of Table 14 provides costs per 1000 gallons of treated ground water in
terms of 30-year total O&M cost, construction, and the combined construction plus 30-year O&M, The lower part of the
table includes PV for Fe maintenance for the three sites (all used Fe as the reactive media) where estimates were
provided. The starting values in the iron maintenance PV calculations were those presented in Table 8 as "Stated Fe
Maintenance." It is assumed that iron maintenance occurs twice, at years 10 and 20, during the 30-year life of the PRB.
We have not questioned or made assumptions regarding the iron maintenance cost estimates for the sites. The columns
in the lower section of Table 14 provide data on (a) the PVcost of iron maintenance for two cycles, (b) iron maintenance
PV with O&M PV, (c) both of the previous plus construction costs, and (d) the total PV cost per 1000 gallons for the 30-
year period. It is evident that iron maintenance can substantially increase the treatment cost; therefore, it is important that
both maintenance techniques and iron longevity receive further study and analysis.
A recent EPA report (U.S. EPA, 1999a) evaluated 28 sites, including cost. Of these 28 sites, three were PRB sites that
have also been evaluated in this report. However, their unit costs in that report were not calculated using PV, but
presented simply 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." Table 15 presents our data for the sites from Table 14 in that context.
It includes the values presented in the recent report for the three PRB sites evaluated in the other EPA report: the USCG
Support Center, Intersil, and Moffett Federal Airfield sites.
Calculating costs in the manner of Table 15, rather than using lifetime values, biases the costs to extremely high initial
values, especially for the construction costs per 1000 gallons. This is because only 1/30th of the total volume of waterthat
is expected to pass through the PRB during its 30-year lifetime is being used as the divisor for the total construction
costs. In addition, in terms of setting aside today's money (PV), the O&M costs are also reduced in the 30-year scenario
relative to the current, a recent, or average year. In Table 15, capital costs per 1000 gallons for the USCG Support Center
and the Intersil site are very close between this document and the U.S. EPA (1999a) report, as are the O&M costs per
1000 gallons for all three sites. This is true even though we used a different approach for the ground-water flow
calculations in this report. However, the capital costs per 1000 gallons are significantly different for the Moffett Federal
Airfield site. This results from estimation differences for the ground-water volume through the PRB system at Moffett.
Ground-water velocity estimates in the A1 surficial sediment unit at Moffett (the zone containing the PRB) range from
0.005 to 2 feet per day (U.S. EPA, 1998b), leaving a large margin for error in calculations4. The similarity in Moffett O&M
costs per 1000 gallons between the reports was simply fortuitous. The higher O&M cost of this report ($90,000/yr versus
$26,000/yrforU.S. EPA, 1999a) was offset by the differences in estimates of annual ground-water volume (796,000 gal-
lons per year versus 200,000 gallons/yr for U.S. EPA, 1999a). The annual volume estimates between the reports were
much closer for the other two sites, hence the cost estimates were very comparable.
Table 14. Various Costs per 1000 Gallons of PRB-treated Water, Using O&M PV Calculations and Factor 1 Esti-
mated Annual Flow Through PRBs for a 30-year Period (Including Fe Maintenance Costs for Sites with
Estimates)
Site
USCG Support Center
Intersil Site
Moffett Federal Airfield
Aircraft Maintenance, OR
Former Manufacturing,
Fairfield, NJ
Nickel Rim, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
Sites with Fe
Maintenance Estimates
Intersil Site + Fe Maint.
Moffett, Full-Scale Est. + Fe
Maint.
Dover, AFB Full-Scale Est.
+ Fe Maint.
Total 30 Yr
Annual
O&M PV
S1.55E+06
S1.74E+06
S1.65E+06
S9.15E+05
S4.57E+05
S5.49E+05
S1.32E+06
S2.71E+06
(A)Fe
Maint. 30 Yr
PV(10yr
cycle)
S4.95E+05
S5.70E+05
S8.98E+05
Calc. PRB
Construction
Cost
S5.00E+05
S6.56E+05
S3.77E+05
S7.00E+05
S7.25E+05
S3.50E+04
S4.62E+06
S5.82E+05
(B) Fe Maint.
30 Yr PV + 30
Yr O&M PV
S2.23E+06
S1.89E+06
S3.60E+06
30 Yr Total
O&M +
Construction
S2.05E+06
S2.39E+06
S2.02E+06
S1.61E+06
S1.18E+06
S5.84E+05
S5.94E+06
S3.29E+06
(A) + (B) +
Calc. PRB
Construction
Cost
$3.38E+06
$7.08E+06
$5.08E+06
Factor 1 (0.67),
GW 1000 Gal
per 30 Yrs
7.97E+04
3.49E+04
2.39E+04
3.09E+05
1.04E+05
4.97E+03
9.46E+05
5.21 E+04
Total PV Cost
per 1000 Gal
over 30 Years
$ 96.80
$ 7.48
$ 97.52
30 Yr O&M
Cost per
1000 Gal
$ 19.51
$ 49.72
$ 68.91
$ 2.96
$ 4.40
$ 110.43
$ 1.40
$ 51.93
30 Yr
Construction
Cost per 1000
Gal
$ 6.27
$ 18.77
$ 15.80
$ 2.27
$ 6.97
$ 7.04
$ 4.88
$ 11.16
30 Yr O&M +
Construction
Cost per 1000
Gal
$ 25.79
$ 68.49
$ 84.71
$ 5.23
$ 1 1 .37
$ 117.47
$ 6.28
$ 63.09
22
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Table 15. Costs per 1000 Gallons Treated by PRB During a Single or Average Year, Including Data from U.S. EPA,
1999a
Site
USCG Support Center
Intersil Site
Moffett Federal Airfield
Aircraft Maintenance, OR
Former Manufacturing, Fairfield, NJ
Nickel Rim, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
Factor 1
(0.67), GW
1000 Gal
per Yr
2.66E+03
1.16E+03
7.96E+02
1.03E+04
3.47E+03
1.66E+02
3.15E+04
1.74E+03
Construction
Cost per 1000
Gal
$ 188
$ 563
$ 474
$ 68
$ 209
$ 211
$ 146
$ 335
Current Year
O&M Cost
per 1000 Gal
$ 32
$ 82
$ 113
$ 5
$ 7
$ 181
$ 2
$ 85
Capital Cost per
1000 Gal GW
Treated Per Year
(U.S. EPA, 1999a)
$ 190
$ 520
$ 1,600
Avg. Annual O&M
Cost per 1000 Gal
GW Treated per
Year (U.S. EPA,
1999a)
$ 33
$ 83
$ 110
7.3, P&T 1000 gallons of
As per Section 7.1, P&T unit costs (i.e., cost per 1000 gallons) should be based on the volumes treated by the PRBs at
the sites, rather than the quantity that could be pumped by the P&T systems. This, as previously stated, assumes that the
PRBs are properly constructed and capturing all the contaminated ground water. This is very important, if one is using
dollars per 1000 gallons as your unit cost, to avoid automatic bias in favor of higher volume P&T systems. For example,
the previously mentioned report (U.S. EPA, 1999a) determines O&M costs per 1000 gallons for both P&T and PRB sites
without making this distinction. This results in a chart where the Moffett PRB is the third most expensive among the 28
sites in terms of average annual O&M costs per 1000 gallons and the Intersil PRB site is fifth. Table 16 shows these costs
and annual ground-water volume, perthe report, for the four most expensive sites. It also recalculates the P&T unit costs
based on the annual flow (from the same report) through the PRB at the Moffett site. When this is done, the P&T unit
costs are much higher than the PRB unit cost. This recalculation is not meant to be accurate. The Moffett data is for a
pilot-scale PRB that was never intended to capture the entire contaminant plume and the recalculated P&T systems are
not located at the Moffett site. The calculation is merely demonstrative of the need to carefully choose the means of unit
comparisons.
However a data comparison between the P&T system, previously operational at the Intersil site, and the current PRB
installation is both demonstrative and indicative of more realistic unit costs. This is shown in Table 17, which again relies
on data from the aforementioned report, that also recalculates the Intersil P&T unit cost based on the PRB annual flow
at the Intersil site. This is reasonable since it is known that the currently installed PRB is accomplishing the remediation
and the P&T system was no longer needed, and was discontinued. Approaching the unit costs in this manner results in
the O&M for the P&T system being nearly 50% more expensive than O&M costs for the PRB, $127 versus $86 per 1000
gallons of treated ground water.
7.4. of P& T unit at the PRB
As mentioned in Section 6.1 and displayed in Tables 10 and 11, nine of the 22 PRB sites evaluated in this report have
either had, or considered, P&T installations. Table 18 displays these data, for both the PRB installations and the P&T in
terms of unit costs as cost per 1000 gallons of treated water. This table confirms that construction costs can go in either
direction, from PRB being far less expensive to far more expensive than a P&T installation. It also establishes, forthe five
cases where data are available, that O&M costs for the PRB systems are likely to be much lower than for P&T systems,
at least when periodic media maintenance costs are not included. Due to a paucity of data, it is difficult to ascertain
whether this O&M cost advantage of PRB systems will persist when periodic media maintenance costs are included.
4 Uncertainty in the ground-water velocity at Moffett could also significantly impact the costs presented in Table 14. A higher velocity
lowers the unit costs; a lower velocity increases them.
23
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Table 16. Evaluation of Reported O&M Unit Costs for Four Sites by Modifying the Unit Basis
Site
Libby
Old Mill
Moffett
City Industries
Type
P&T
P&T
PRB
P&T
Avg. Annual
O&M Cost
(U.S. EPA,
1999a)
$ 500,000
$ 210,000
$ 26,000
$ 170,000
1000 Gallons of
GW Treated perYr
(U.S. EPA, 1999a)
2900
1700
200
50000
Annual O&M per
1000 Gal (U.S.
EPA, 1999a)
$ 170
$ 130
$ 110
$ 97
Annual O&M per
1000 Gal at Moffett
PRB GW Volume
$ 2,500
$ 1,050
$ 130
$ 850
Table 17. Evaluation of Reported P&T Versus PRB Unit Costs at the Intersil Site by Modifying the Unit Basis
Site
Intersil
Intersil
Type
P&T
PRB
Avg. Annual
O&M Cost
(U.S. EPA,
1999a)
$ 140,000
$ 95,000
1000 Gallons of
GWTreated perYr
(U.S. EPA, 1999a)
5000
1100
Annual O&M per
1000 Gal (U.S.
EPA, 1999a)
$ 28
$ 83
Annual O&M per
1000 Gal at Intersil
PRB GWVolume
$ 127
$ 86
Table 18. Comparison of Costs per 1000 Gallons of Treated Ground Water for Construction and O&M Costs Using
PRB and P&T Technologies at the PRB Sites in this Study
Site
USCG Support Center
Intersil Site
Watervliet Arsenal
Moffett Federal Airfield
Somersworth Landfill SF Site
Dover AFB, DE
Kansas City Plant, MO
Aircraft Maintenance, OR
Caldwell Trucking, NJ
Former Manufacturing, Fairfield,
NJ
Industrial Site, Coffeyville, KS
Industrial Site, NY
Industrial Site, SC
Nickel Rim, Ontario
Cape Canaveral, FL
MMRCS-10 Plume, MA
Pease AFB, NH
Vancouver, Canada
Warren AFB Spill Site 7, WY
London, Ontario
Moffett, Full-Scale Est.
Dover, AFB Full-Scale Est.
Factor 1
GW
Volume,
1000 Gal/Yr
2.66E+03
1.16E+03
5.19E+02
7.96E+02
7.28E+04
8.69E+02
4.19E+03
1 .03E+04
1 .80E+04
3.47E+03
3.34E+04
7.27E+03
2.40E+03
1 .66E+02
4.10E+02
8.74E+03
O.OOE+00
O.OOE+00
1.40E+04
O.OOE+00
3.15E+04
1 .74E+03
A PRB
Construction
Cost per
1000 Gal
$ 188
$ 563
$ 528
$ 474
$ 29
$ 412
$ 296
$ 68
$
$ 209
$ 12
$ 137
$ 148
$ 211
$ 1,781
-
NA
NA
$ 168
NA
$ 146
$ 335
B. P&T
Construction
Cost per
1000 Gal
$ 188
$ 279
$ 1 ,608
-
$ 357
$
$
$
$
$ 101
$
$
$
$
$
-
NA
NA
$
NA
$ 44
$ 289
A-B
Construction
Costs per
1000 Gal
$
$ 284
$ (1 ,079)
NA
$ (328)
NA
NA
NA
NA
$ 108
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
$ 102
$ 46
C. Current
Year
(Annual)
PRB O&M
Cost per
1000 Gal
$ 32
$ 82
$
$ 113
$
$
$
$ 5
$
$ 7
$
$
$
$ 181
$
-
NA
NA
$
NA
$ 2
$ 85
D. Current
Year
(Annual)
P&T O&M
Cost per
1000 Gal
$ 75
$ 122
$
$
$ 47
-
$ 48
$
$
$ 28
$
$ 41
$
$
$
-
NA
NA
$
NA
$ 22
$ 126
C-D Current
Year
(Annual)
O&M Costs
per 1000 Gal
$ (43)
$ (40)
NA
NA
NA
NA
NA
NA
NA
$ (21)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
$ (20)
$ (41)
24
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8. Summary Conclusions
Permeable reactive barrier technologies have been incorporated at a large number of sites during the past decade and
particularly during the past five years. A record of accomplishment for these PRB sites has begun to develop. In most
cases, these systems have been very effective at achieving the site remediation goals. It is now incumbent upon the
remediation community to better understand the cost-effectiveness of these systems, as PRB technology is added to the
list of standard approaches that can be considered during a remediation feasibility study.
The analyses done for this report indicate several items of major importance that must be addressed before the cost-
effectiveness of PRB systems can be fully assessed, some of which are also applicable to other technology
assessments:
1. It is critical that all costs be fully tracked and documented during the planning, installation and operation of
PRB systems. This should be done for all remedial options and systems, not just PRBs. Guidelines, such as
those from the FRTR, have been developed and should be used. Lack of such detailed information weakens
comparative analyses and makes them less meaningful.
2. The longevity of the PRB systems and the need, frequency, and extent of media maintenance are critical
factors for confirming the initial perception of cost-effectiveness that has accompanied these systems.
Additional studies are needed to determine when media maintenance will be necessary and to determine the
best and most economical methods for maintenance should it be required.
3. Using traditional unit costs (costs per 1000 gallons) can be misleading when applied to comparing PRB and
P&T system cost-effectiveness. This is because PRB systems are fundamentally different in their approach
to contaminant remediation from P&T systems and almost never process as much water during a year. It is
important to find a relevant basis of unit comparison and both explain and support it when contrasting the
feasibility of these two approaches.
This report draws no absolute conclusions regarding the cost-effectiveness of PRB systems relative to P&T systems.
This is in large part due to the paucity of available information on installed sites and the lack of knowledge of system
longevity that currently exists (numbers 1 and 2, above). The results seem to indicate that PRB systems will generally be
cheaper and less troublesome to operate and maintain, especially if periodic reactive media maintenance is not needed.
It is likely that cost-effectiveness will depend extensively on the nature of the site and the contaminants. It is also
important to consider the less obvious benefits of PRB technologies, relative to P&T, which do not appear in typical cost-
comparison exercises. Among these benefits are:
1. In situ technique
a. minimizes exposure of individuals at the surface to the contaminants
b. minimizes exposure of individuals at the surface to chemicals used in the P&T treatment trains
c. minimizes cross-media transfer of the contaminants (e.g., water to atmosphere)
d. allows the land surface to continue to be used for other purposes (e.g., can be re-paved following PRB
installation)
e. eliminates (in most cases) the need for additional onsite treatment or transport and disposal of
contaminated media typically generated by P&T systems; e.g., regeneration of activated carbon and ion
exchange resins, disposal of sludge
2. Passive technology
a. eliminates the need for utility hook-ups, and energy usage following construction
b. doesn't pull uncontaminated water to mix with the contaminated plume as P&T systems can
c. remediation effectiveness not limited by slow contaminant desorption/dissolution processes since the
PRB lies in the path of the resultant plume
d. eliminates the need for full or part-time on-site personnel to maintain the system
Although the costs of PRB systems are not yet absolutely established, it is important to continue installing, documenting,
and investigating these systems where appropriate. They remain a powerful addition to a remedial toolkit that has too few
effective options for dealing with subsurface contamination.
25
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Blowes, D. W., Ptacek, C. J. and J. L. Jambor(1997). "In-Situ remediation of chromate contaminated groundwater using
permeable reactive walls: Laboratory studies." Environ. Sci. &Technol. 31: 3348-3357.
FRTR-U.S. EPA (1998). "Guide to Documenting and Managing Cost and Performance Information for Remediation
Projects." Prepared by Member Agencies of the Federal Remediation Technologies Roundtable (FRTR) [www.frtr.gov].
EPA 542-B-98-007.
Gavaskar, A., Gupta, N., Sass, B., Janosy, R. and J. Hicks (2000). "Design Guidance for Application of Permeable
Reactive Barriers for Groundwater Remediation." Prepared by Battelle, Columbus, Ohio, March 31, 2000 for the
Air Force Research Laboratory, Tyndall Air Force Base, Florida, Sponsored by SERDP. RN: A012.
Gillham, R. W. (1995). "Resurgence in research concerning organic transformations enhanced by zero-valent metals
and potential application in remediation of contaminated groundwater." 209th ACS National Meeting. April 2-7.
American Chemical Society, Division of Environmental Chemistry, Anaheim, California, pp. 691-694.
Heneman, F. C., May, M. R., Walsh, R. C., Perez, E. J., and G. B. Enloe. 2000. "Building a Better Iron Wall: The Largest
Iron-Filings Permeable Reactive Barrier Built for the Department of Defense, F. E. Warren AFB, Wyoming." URS.
Denver, Colorado.
Keely, J. F. (1989). "Performance evaluations of pump-and-treat remediations." U.S. Environmental Protection Agency,
Superfund Ground Water Issue. Robert S. Kerr Environmental Research Laboratory. EPA/540/4-89/005.
NRC (1994). Alternatives for Ground Water Cleanup. National Academy Press, Washington, D.C.
O' Hannesin, S. (1998). "Groundwater Remediation Using In-Situ Treatment Walls." Presented at the GWRTAC/EPA
TIO 2nd Advances in Innovative Ground-Water Remediation Technologies Conference in San Francisco, California,
May 6.
Powell, R. M., Puls, R. W., Hightower, S. K. and D. A. Sabatini (1995). "Coupled iron corrosion and chromate reduction:
Mechanisms for subsurface remediation." Environ. Sci. &Technol. 29: 1913-1922.
Powell, R. M., Puls, R. W., Blowes, D., Vogan, J., Gillham, R. W., Powell, P. D., Schultz, D., Landis, R., and T. Sivavec.
(1998). "Permeable Reactive Barrier Technologies for Contaminant Remediation." U.S. Environmental Protection
Agency, Office of Research and Development. EPA/600/R-98/125.
Powell, R. M. and P. D. Powell (1998). "Iron Metal for Subsurface Remediation." in The Encyclopedia of Environmental
Analysis and Remediation. Robert A. Myers, ed. John Wiley & Sons, Inc., New York. 8:4729-4761.
Roberts, A. L., Totten, L. A., Arnold, W. A., Burris, D. R., and T. J. Campbell (1996). "Reductive Elimination of Chlorinated
Ethylenes by Zero-valent Metals." Environ. Sci. &Technol. 30(8): 2654-2659.
RTDF (2000). "Summary of the Remediation Technologies Development Forum." Permeable Reactive Barriers Action
Team Meeting. Hilton Melbourne Airport, Melbourne, Florida, February 16-17.
U.S. DOD (1999). "ESTCP Cost and Performance Report: Permeable Reactive Wall Remediation of Chlorinated
Hydrocarbons in Groundwater." U.S. Department of Defense, Environmental Security Technology Certification
Program (ESTCP).
U.S. EPA (1998a). "EnviroMetal Technologies, Inc.: Metal-Enhanced Dechlorination of Volatile Organic Compounds
Using an In-Situ Reactive Iron Wall." Innovative Technology Evaluation Report. U.S. Environmental Protection
Agency, Office of Research and Development, National Risk Management Research Laboratory. EPA/540/R-98/501.
U.S. EPA (1998b). "Remediation Case Studies: Innovative Groundwater Treatment Technologies, Volume 11."
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, Technology Innovation
Office. EPA 542-R-98-015.
U.S. EPA (1999a). "Groundwater Cleanup: Overview of Operating Experience at 28 Sites." U.S. Environmental
Protection Agency, Office of Solid Waste and Emergency Response. EPA 542-R-99-006.
U.S. EPA (1999b). "Field Applications of In Situ Remediation Technologies: Permeable Reactive Barriers."
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response. EPA 542-R-99-002.
U.S. EPA (2001). "Cost Analyses for Selected Groundwater Cleanup Projects: Pump and Treat Systems and Permeable
Reactive Barriers." U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response.
EPA542-R-00-013.
26
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A
Site Name:
Contact:
and
Reactive Barrier Information:
Barrier Type (Circle or Select)
| Funnel & Gate \ Trench \ Container \ Other
Reactive Material (e.g., Fe°)
Reactive Material Mass, Tons
Treated Contaminants (TCE, etc.)
Scale (Full or Pilot)
Contain Cone Maxima in jjg/L
Est Total Plume Volume, L
Est. Plume Contain. Mass, Kg
Separate Source Treatment? \ Yes \ No \
TOTAL PRB Cost> $
PRB Treatment Unit Cost
(e.g., $/lb TCE treated; $1000/lb TCE)
Characterization
Exploration Well Installation Costs
Exp Well Sampling Costs
Exp Well Analytical Costs
Push Tool Exploration Costs
Coring Costs
Core Test Costs
Geologic/Stratigraphic Costs
Hydrologic Test Costs
Site Characteriz. Equipment Costs
Other Characterization Costs
Description of Other Char Costs:
TOTAL Site Char Costs>
Site Characterization Notes:
P&T Information:
Onsite P&T System or Cost Estimate? (Circle or Select)
| Yes | No | Estimate \
P&T Total Startup Cost or Estimate $
P&T Unit Cost (e.g., $/lb TCE) $
Annual P&T O&M Cost
Site Info Notes:
Design
Lab Tests/Data/Statistical Analysis Costs
Modeling Costs $
Alternatives Comparison Costs $
Design Plans/Arch. Drawing Costs $
Other Design Costs $
Description of Other Design Costs:
TOTAL Design Cost> $
Design Notes:
27
-------
Construction
Reactive Media Costs
Funnel Costs
Gate Costs
Trench Costs
Mobilization Costs
Equipment Costs
Health/Safety Costs
Installation/Labor Costs
Materials Disposal Costs
Other Construction Costs
Describe Other Construction Costs:
TOTAL Construction >
Construction Notes:
Monitoring / O&M
# of Compliance MWs (CMW)
Avg. Cost of CMW
# of Performance MWs (PMW)
Avg. Cost of PMW
Sampling Events / Year
Cost / Sampling Event
Analytical Cost / Event
Monitoring Equipment Cost
Annual Monitoring Cost
Annual Reporting Cost
Cost of MWs added just for PRB
Other Initial Monit./Sampling Costs
Describe Other Monit./Sampl. Costs:
Monitoring Notes:
Licensing and Reports
PRB License Fee
Funnel/Gate License Fee
Other License Cost
Design/Construction Report Costs
Annual License Renewal
TOTAL Initial Lie. & Report Costs >
Licenses & Reports Notes:
Other
Other Annual O&M Costs $
Describe Other O&M Costs:
Post Installation (PI) PRB Modifications?
| Yes | A/o |
PI PRB Cost $
Why Were Pi PRB Mods Made?
Additional Plume Treatments Required?
| Yes | A/o |
Additional Treatment Cost/Year $
Why Were Additional Treatments Needed
TOTAL Annual O&M Costs> $
O&M Notes:
28
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B
Acknowledgments
The U.S. Environmental Protection Agency, Dynamac Corporation and Powell & Associates Science Services wish to
thank all who participated in providing valuable information regarding PRB costs at the various sites for this report. Their
efforts make this document a useful tool for improving decisions regarding implementation of permeable reactive barriers
as an alternative to pump-and-treat. Below is a list of those who contributed information to the development of this report.
Facility, OR
David Weymann, P.E., PSS
The IT Group
15055 SWSequoia Parkway, Suite 1400
Portland, OR 97224
Tel: (503) 624-7200 ext 543
Fax: (503) 624-7200
dweymann@theitgroup.com
Jerry Hansen
US Air Force Center For Environmental Excellence
3207 North Road
Brooks AFB, TX 78235-5363
Tel: (210)536-4353
Fax: (210)536-4330
jerry.hansen@hqafcee.brooks.af.mil
Stephen Tapped
TRC VECTRE Corporation
333 Route 46 West
Suite 202
Mountain Lakes, NJ 07046
Tel: (973) 402-9900
Fax: (973) 402-4656
STappert@trcsolutions.com
SC
Steven Schroeder
RMT, Inc.
100VerdaeBlvd.,
PO Box 16778
Greensville, SC 29606-6778
Tel: (864)281-0030
Fax: (864) 287-0288
steve.schroeder@rmtinc.com
Intersil
Dominique Sorel
Project Hydrogeologist
Geomatrix Consultants
2101 Webster St, 12th floor
Oakland, CA 94612
Tel: (510)663-4161
Fax: (510)663-4141
dsorel@geomatrix.com
City
Paul Dieckmann
Allied Signal PM&T
2000 East 95th Street
PO Box 419159
Kansas City, MO 64141-6159
Tel: (816)997-2335
Fax: (816)997-7361
pdieckmann@KCP.com
29
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Arun Gavaskar
Battelle Memorial Institute
505 King Avenue
Columbus, OH 43201
Tel: (614)424-3403
Fax: (614)424-3667
gavaskar@battelle.org
Rim,
David Blowes
Waterloo Centre For Groundwater Research
University Of Waterloo
Waterloo, ONTARIO
Tel: (519) 888-4878
Fax:(519)746-5644
blowes@sciborg.uwaterloo.ca
Jeffrey Cange
Bechtel Environmental
151 Layfayette Drive
P.O. BoxSSOO
Oak Ridge, TN 37831-0350
Tel: (423)
Fax: (423)220-2108
jbcange@bechtel.com
Roger Diiwart
U.S. EPA Region 1
1 Congress Street, Suite 1100 (HBO)
Boston, MA 02114-2023
Tel: (617) 918-1259
Fax: (617)918-1291
duwart.roger@epa.gov
USCG Center, City, NC
Robert Puls
U.S. Environmental Protection Agency
R. S. Kerr Environmental Research Center
PO Box 1198
Ada, OK 74821-1198
Tel: 580-436-8543
Fax: 580-436-8703
puls.robert@epamail.epa.gov
Vancouver,
Eric Pringle
Hemmera Envirochem Inc.
Suite 350, 1190 Hornby Street
Vancouver, British Columbia V6Z2K5, Canada
Tel: (604) 669-0424
Fax: (604) 669-0430
eric.pringle@conorpacific.com
/IFJ3
Michael May
URS Greiner
4582 South Ulster Street
Denver, CO 80237-2637
Tel: (303) 740-3863
michaeLmay@urscorp.com
Russell Marsh
US Army Corps Of Engineers
P.O. Box1715
Baltimore, MD21203
Tel: (410)962-2227
Fax: (410)962-2318
russell.e.marsh@usace.army.mil
30
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31
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Research Laboratory
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