1

United States

Environmental Protection

Agency

Economic Analysis of the

Implementation of Permeable

Reactive Barriers for

Remediation of Contaminated

Ground Water
EPA/600/R-02/034

June 2002

Economic Analysis of the

Implementation of Permeable Reactive

Barriers for Remediation of Contaminated

Ground Water

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
ii

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 environmental 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, understand 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 technological 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 environment; 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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Abstract

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. Subcategories 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 per the quantity of water that 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 for the Pump-and-Treat Sites....................................................................... 15

6.1 P&T at the 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 1st 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
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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 for the PRB Sites ..................................................................................... 15

9. PRB Information Relevant to Maintenance Costs ....................................................... 16

10. P&T Information for the 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
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SI Conversion Factors

English (US) Metric (SI)

Multiply Units by Factor to get Units

Area: 1 ft2 0.0929 m2

1 in2 6.452 cm2

Flow rate: 1 gal/min 6.31 x 10-5 m3/s

1 gal/min 0.0631 L/s

1 MGD 43.81 L/s

Length: 1 ft 0.3048 m

1 in 2.54 cm

Mass: 1 lb 453.59 g

1 lb 0.45359 kg

Volume: 1 ft3 28.316 L

1 ft3 0.028317 m3

1 gal 3.785 L

1 gal 0.003785 m3

Temperature: oF - 32 0.55556 oC

Concentration: 1 gr/ft3 2.2884 g/m3

1 gr/gal 0.0171 g/L

1 lb/ft3 16.03 g/L

Pressure: 1 lb/in2 0.07031 kg/cm2

1 lb/in2 6894.8 Newton/m2

Heating value: Btu/lb 2326 Joules/kg

Btu/scf 37260 Joules/scm
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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 contaminated 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). Rather than 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 contaminant(s) 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 CrO4

2-), 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 (O’ Hannesin, 1998) or proposed (U.S. DOD, 1999; Gavaskar et al., 2000) for the site. The

intent of this document is to further document PRB costs and assess 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 for a 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 Report

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 for the unit comparisons. Additionally, there are

other intangible benefits to using PRB technology that do not often show up in cost comparisons.

3. PRB Sites Evaluated

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 Fe0

), 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 -> C2

H2 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 (CrO4

2- or HCrO4-

) to Cr(III) and immobilizing it in the subsurface (Powell
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Table 1. Basic PRB Site Information

Site PRB Type

Reactive

Material

Mass,

Tons

Treated

Contaminants

PRB

Scale

On-Site

P&T?

Research

Site?

USCG Support Center Trench Fe(0) 450 TCE; Cr(VI) Full-scale Estimated Yes

Intersil Site F&G Fe(0) 220

TCE; c-1,2-DCE; VC;

Freon 113 Full-scale Yes No

Watervliet Arsenal Trench Fe(0) 166

PCE; TCE; cDCE;

tDCE; VC Pilot-scale Estimated No

Moffett Federal Airfield F&G Fe(0) 75 TCE; 1,2-DCE; PCE Pilot-scale 0 Yes

Somersworth Landfill SF

Site Trench Fe(0) 3552

PCE; TCE; cDCE;

VC Full-scale Estimated No

Dover AFB, DE F&G Fe(0) 59 PCE; TCE; DCE Pilot-scale 0 Yes

Kansas City Plant, MO Trench Fe(0) 650 TCE; 1,2-DCE; VC Full-scale Yes No

Aircraft Maintenance, OR F&G Fe(0) 324 PCE, TCE Full-scale No No

Caldwell Trucking, NJ

Hydr.

Frac./Perm.

Infill Fe(0) 250 TCE Full-scale ND No

Former Manufacturing,

Fairfield, NJ Trench Fe(0) 720 1,1,1-TCA; PCE; TCE Full-scale Estimated No

Industrial Site, Coffeyville,

KS F&G Fe(0) 70 TCE; 1,1,1-TCA Full-scale ND No

Industrial Site, NY Trench Fe(0) 742 TCE; cDCE; VC Full-scale Estimated No

Industrial Site, SC Trench Fe(0) 400 TCE; cDCE; VC Full-scale ND No

Nickel Rim, Ontario Trench

Organic

Matter 425 Ni; Fe; SO4 Full-scale No No

Cape Canaveral, FL Trench Fe(0) 205 TCE; DCE; VC Pilot-scale ND Yes

MMR CS-10 Plume, MA

Hydr.

Frac./Perm.

Infill Fe(0) 49 PCE; TCE Pilot-scale ND No

Pease AFB, NH Trench Fe(0) 360

TCE; cis-1,2-DCE;

VC Full-scale ND No

Vancouver, Canada Trench

Organic

Matter 0 Cu, Zn, Cd, Ni Pilot-scale ND No

Warren AFB Spill Site 7,

WY Trench Fe(0) 1750 TCE, DCE, VC Full-scale ND No

London, Ontario Trench

Oxygen

furnace slag 400 Phosphate Full-scale ND No

Moffett, Full-Scale Est. F&G Fe(0) 2518 TCE; 1,2-DCE; PCE Full-scale Estimated No

Dover, AFB Full-Scale

Est. F&G Fe(0) 108 PCE; TCE; DCE Full-scale Estimated 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 pilotscale 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 and 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 and print information sources

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. Telephone contacts

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. Emailed forms

Detailed information acquisition forms were emailed to all site contacts. These were provided for their use in responding

to our queries 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. Vendor visits

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 patentholders and licensers of the PRB technology as it applies to ZVI 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. Information quality

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
5

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. Information storage and organization

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 Excel® and 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. Cost parameter breakdown

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, ETI, 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 Data for the Permeable Reactive Barrier Sites

5.1. Stated versus calculated costs for the PRB sites

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 for the stated costs for the remaining sites, when available, are also referenced in Table 2.

In addition to stated costs, a “Calculated Approximate 1st 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
6

Table 2. PRB Stated Costs and Sources

Site Stated Cost Source Stated PRB Cost

USCG Support Center RTDF $               500,000

Intersil Site RTDF $            1,000,000

Watervliet Arsenal RTDF $               387,000

Moffett Federal Airfield RTDF $               540,000

Somersworth Landfill SF Site O'Hannesin, 1998 $            2,100,000

Dover AFB, DE RTDF $               800,000

Kansas City Plant, MO RTDF $            1,500,000

Aircraft Maintenance, OR RTDF $               600,000

Caldwell Trucking, NJ RTDF $            1,120,000

Former Manufacturing, Fairfield, NJ RTDF $               875,000

Industrial Site, Coffeyville, KS RTDF $               400,000

Industrial Site, NY RTDF $               797,000

Industrial Site, SC RTDF $               400,000

Nickel Rim, Ontario RTDF $                 30,000

Cape Canaveral, FL RTDF $               809,000

MMR CS-10 Plume, MA RTDF $               160,000

Pease AFB, NH Gavaskar et al., 2000 $               300,000

Vancouver, Canada Personal Comm. $                 25,000

Warren AFB Spill Site 7, WY Heneman et al., 2000 $            2,350,000

London, Ontario NA $                         -

Moffett, Full-Scale Est. U.S. DOD, 1999 $            4,910,942

Dover, AFB Full-Scale Est. Gavaskar et al., 2000 $               947,000

It should be noted that values for many of these cost categories were not available for several of the sites, therefore the

1st 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.

Table 3 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, 1st 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).

For three 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. PRB site characterization costs

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. PRB design costs

Five categories of PRB design costs were sought for this study. These were:

1. Tests, data, and statistical analysis costs

2. Modeling costs
7

Table 3. Calculated PRB Costs Relative to Stated PRB Costs

Site

Stated PRB

Cost

Calculated

Approximate

1st Yr. Cost

Stated Cost

Minus 1st

Yr. Cost

Calculated

Construction

Cost

Stated Cost

Minus

Construction

USCG Support Center 500,000 $         $        1,070,000 $       (570,000) $           500,000 $0

Intersil Site 1,000,000 $       $        1,005,000 $          (5,000) $           656,000 $344,000

Watervliet Arsenal 387,000 $         $           387,000 $                  - $           274,000 $113,000

Moffett Federal Airfield 540,000 $         $           742,375 $       (202,375) $           377,375 $162,625

Somersworth Landfill SF Site 2,100,000 $       $        2,515,000 $       (415,000) $         2,100,000 $0

Dover AFB, DE 800,000 $         $           739,000 $         61,000 $           358,000 $442,000

Kansas City Plant, MO 1,500,000 $       $        1,490,000 $         10,000 $         1,240,000 $260,000

Aircraft Maintenance, OR 600,000 $         $        1,135,000 $       (535,000) $           700,000 ($100,000)

Caldwell Trucking, NJ 1,120,000 $       $                        - $                      - -

Former Manufacturing, Fairfield, NJ 875,000 $         $           900,000 $        (25,000) $           725,000 $150,000

Industrial Site, Coffeyville, KS 400,000 $         $           400,000 $                  - $           400,000 $0

Industrial Site, NY 797,000 $         $        1,000,000 $       (203,000) $         1,000,000 ($203,000)

Industrial Site, SC 400,000 $         $           400,000 $                  - $           356,000 $44,000

Nickel Rim, Ontario 30,000 $           $           120,000 $        (90,000) $             35,000 ($5,000)

Cape Canaveral, FL 809,000 $         $           760,150 $         48,850 $           729,250 $79,750

MMR CS-10 Plume, MA 160,000 $         $                        - $                      - -

Pease AFB, NH 300,000 $         $        1,250,000 $       (950,000) $           550,000 ($250,000)

Vancouver, Canada 25,000 $           $                        - $                      - -

Warren AFB Spill Site 7, WY 2,350,000 $       $        2,350,000 $                  - $         2,350,000 $0

London, Ontario - $                    $               29,700 $             26,700 -

Moffett, Full-Scale Est. 4,910,942 $       $        4,983,220 $        (72,278) $         4,618,122 $292,820

Dover, AFB Full-Scale Est. 947,000 $         $        1,095,000 $       (148,000) $           582,000 $365,000

Figure 1. Bar plot of Stated Cost, Calculated Approximate 1st Year Cost, and Calculated Construction Cost for the

PRB sites.

$0 $1,000,000 $2,000,000 $3,000,000 $4,000,000 $5,000,000

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.

Sites

Cost

Stated PRB Cost

Calculated Approximate 1st Yr. Cost

Calculated Construction Cost
8

Site Tests/Stats Modeling

Alternatives

Comparison

Plans/

Drawings Other

Design

Total

USCG Support Center 25,000 $          $     10,000 $                      - $       35,000 $       75,000 $     145,000

Intersil Site - $                   $              - $                      - $     100,000 $     154,000 $     254,000

Watervliet Arsenal - $                   $              - $                      - $                - $     113,000 $     113,000

Moffett Federal Airfield 75,000 $          $              - $                      - $                - $     100,000 $     175,000

Somersworth Landfill SF Site 100,000 $        $     40,000 $           100,000 $     100,000 $                - $     340,000

Dover AFB, DE 100,000 $        $              - $                      - $                - $     100,000 $     200,000

Kansas City Plant, MO - $                   $              - $                      - $                - $     100,000 $     100,000

Aircraft Maintenance, OR - $                   $     15,000 $             10,000 $                - $       10,000 $       35,000

Caldwell Trucking, NJ - $                   $              - $                      - $                - $                - $                -

Former Manufacturing, Fairfield, NJ - $                   $              - $                      - $                - $     150,000 $     150,000

Industrial Site, Coffeyville, KS - $                   $              - $                      - $                - $                - $                -

Industrial Site, NY - $                   $              - $                      - $                - $                - $                -

Industrial Site, SC - $                   $              - $                      - $                - $       44,000 $       44,000

Nickel Rim, Ontario 30,000 $          $              - $                      - $                - $                - $       30,000

Cape Canaveral, FL 30,900 $          $              - $                      - $                - $                - $       30,900

MMR CS-10 Plume, MA - $                   $              - $                      - $                - $                - $                -

Pease AFB, NH - $                   $              - $                      - $                - $     200,000 $     200,000

Vancouver, Canada - $                   $              - $                      - $                - $                - $                -

Warren AFB Spill Site 7, WY - $                   $              - $                      - $                - $                - $                -

London, Ontario - $                   $              - $                      - $                - $                - $                -

Moffett, Full-Scale Est. 75,000 $          $              - $                      - $     100,000 $                - $     175,000

Dover, AFB Full-Scale Est. 50,000 $          $              - $                      - $                - $     100,000 $     150,000

Table 4. Design Cost Breakdown 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

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.”
9

Figure 2. PRB design cost breakdown for USCG Support Center, North Carolina.

Figure 3. PRB design cost breakdown for Somersworth Landfill, New Hampshire.

USCG Support Center

17%

7%

0%

24%

52%

Tests/Stats

Modeling

Alternatives Comparison

Plans/ Drawings

Other

Design Total = $145,000

Somersworth Landfill SF Site

30%

12%

29%

29%

Tests/Stats

Modeling

Alternatives Comparison

Plans/ Drawings

Design Total = $340,000
10

Table 5. Construction Cost Breakdown for the PRB Sites

Site

Reactive 

Media Funnels Gates Trench Mobilization

Equipm

ent

Health & 

Safety

Installation 

& Labor

Materials 

Disposal Other

Construction 

Total

USCG Support Center $ 200,000 $ - $ - $ 150,000 $ - $ - $ - $ - $ 150,000 $ - $ 500,000 

Intersil Site $ 170,000 $ 178,000 $ 100,000 $ - $ - $ - $ - $ 75,000 $ 50,000 $ 65,000 $ 638,000 

Watervliet Arsenal $ 87,360 $ - $ - $ - $ - $ - $ - $ - $ - $ 169,640 $ 257,000 Moffett Federal Airfield $ 39,375 $ 60,000 $ 100,000 $ - $ - $ - $ - $ - $ - $ 133,000 $ 332,375 

Somersworth Landfill SF Site $ 1,200,000 $ - $ - $ 750,000 $ 150,000 $ - $ - $ - $ - $ - $ 2,100,000 Dover AFB, DE $ 47,000 $ 51,000 $ 133,000 $ - $ 38,000 $ - $ - $ - $ 10,000 $ 17,000 $ 296,000 

Kansas City Plant, MO $ - $ - $ - $ - $ - $ - $ - $ - $ 220,000 $ 980,000 $ 1,200,000 

Aircraft Maintenance, OR $ - $ - $ - $ - $ - $ - $ - $ 650,000 $ - $ 50,000 $ 700,000 

Caldwell Trucking, NJ $ - $ - $ - $ - $ - $ - $ - $ - $ - $ - $ - 

Former Manufacturing, Fairfield, NJ $ 359,000 $ - $ - $ - $ - $ - $ - $ - $ - $ 366,000 $ 725,000 

Industrial Site, Coffeyville, KS $ 50,000 $ - $ - $ - $ - $ - $ - $ - $ - $ 350,000 $ 400,000 Industrial Site, NY $ 358,000 $ - $ - $ - $ - $ - $ - $ - $ - $ 642,000 $ 1,000,000 

Industrial Site, SC $ 133,000 $ - $ - $ - $ - $ - $ - $ - $ - $ 223,000 $ 356,000 Nickel Rim, Ontario $ 15,000 $ - $ - $ - $ - $ - $ - $ 15,000 $ - $ 5,000 $ 35,000 Cape Canaveral, FL $ - $ - $ - $ - $ 115,000 $ - $ - $ 614,250 $ - $ - $ 729,250 

MMR CS-10 Plume, MA $ - $ - $ - $ - $ - $ - $ - $ - $ - $ - $ - 

Pease AFB, NH $ - $ - $ - $ - $ - $ - $ - $ - $ - $ 500,000 $ 500,000 

Vancouver, Canada $ - $ - $ - $ - $ - $ - $ - $ - $ - $ - $ - Warren AFB Spill Site 7, WY $ 600,000 $ - $ - $ - $ - $ - $ - $ 1,400,000 $ - $ 200,000 $ 2,200,000 London, Ontario $ 8,000 $ - $ - $ 6,700 $ 4,000 $ - $ - $ 5,000 $ - $ - $ 23,700 

Moffett, Full-Scale Est. $ 881,300 $ 1,156,164 $ 966,610 $ 557,812 $ 39,693 $ - $ 271,047 $ - $ 404,359 $ 295,137 $ 4,572,122 Dover, AFB Full-Scale Est. $ 48,000 $ 102,000 $ 266,000 $ - $ 60,000 $ - $ - $ - $ - $ 44,000 $ 520,000 
11

5.5. Major cost/capital cost 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. Operation and maintenance at the PRB sites

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.
12

Site

Site

Characterization   Design   Construction   Total

USCG Support Center 150,000 $                   $     145,000 $            500,000 $        795,000

Intersil Site - $                             $     254,000 $            638,000 $        892,000

Watervliet Arsenal - $                             $     113,000 $            257,000 $        370,000

Moffett Federal Airfield 100,000 $                   $     175,000 $            332,375 $        607,375

Somersworth Landfill SF Site - $                             $     340,000 $         2,100,000 $     2,440,000

Dover AFB, DE 165,000 $                   $     200,000 $            296,000 $        661,000

Kansas City Plant, MO 150,000 $                   $     100,000 $         1,200,000 $     1,450,000

Aircraft Maintenance, OR 350,000 $                   $       35,000 $            700,000 $     1,085,000

Caldwell Trucking, NJ - $                             $                - $                      - $                   -

Former Manufacturing, Fairfield, NJ - $                             $     150,000 $            725,000 $        875,000

Industrial Site, Coffeyville, KS - $                             $                - $            400,000 $        400,000

Industrial Site, NY - $                             $                - $         1,000,000 $     1,000,000

Industrial Site, SC - $                             $       44,000 $            356,000 $        400,000

Nickel Rim, Ontario 25,000 $                    $       30,000 $             35,000 $          90,000

Cape Canaveral, FL - $                             $       30,900 $            729,250 $        760,150

MMR CS-10 Plume, MA - $                             $                - $                      - $                   -

Pease AFB, NH 400,000 $                   $     200,000 $            500,000 $     1,100,000

Vancouver, Canada - $                             $                - $                      - $                   -

Warren AFB Spill Site 7, WY - $                             $                - $         2,200,000 $     2,200,000

London, Ontario - $                             $                - $             23,700 $          23,700

Moffett, Full-Scale Est. 117,820 $                   $     175,000 $         4,572,122 $     4,864,942

Dover, AFB Full-Scale Est. 215,000 $                   $     150,000 $            520,000 $        885,000

Figure 4. Major cost components for the PRB sites.

Table 6. Major Cost Components for the PRB Sites

$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 SF Site

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.

Sites

Cost

Site Characterization

Design

Construction
13

Site   Design Construction

PRB

License

Initial

Reporting

Capital Cost

Total

USCG Support Center 145,000 $      $         500,000 $                - $     190,000 $        835,000

Intersil Site 254,000 $      $         638,000 $                - $                - $        892,000

Watervliet Arsenal 113,000 $      $         257,000 $       17,000 $                - $        387,000

Moffett Federal Airfield 175,000 $      $         332,375 $                - $                - $        507,375

Somersworth Landfill SF Site 340,000 $      $      2,100,000 $                - $       75,000 $     2,515,000

Dover AFB, DE 200,000 $      $         296,000 $                - $                - $        496,000

Kansas City Plant, MO 100,000 $      $      1,200,000 $                - $                - $     1,300,000

Aircraft Maintenance, OR 35,000 $        $         700,000 $                - $                - $        735,000

Caldwell Trucking, NJ - $                 $                    - $                - $                - $                   -

Former Manufacturing, Fairfield, NJ 150,000 $      $         725,000 $                - $                - $        875,000

Industrial Site, Coffeyville, KS - $                 $         400,000 $                - $                - $        400,000

Industrial Site, NY - $                 $      1,000,000 $                - $                - $     1,000,000

Industrial Site, SC 44,000 $        $         356,000 $                - $                - $        400,000

Nickel Rim, Ontario 30,000 $        $           35,000 $                - $                - $          65,000

Cape Canaveral, FL 30,900 $        $         729,250 $                - $                - $        760,150

MMR CS-10 Plume, MA - $                 $                    - $                - $                - $                   -

Pease AFB, NH 200,000 $      $         500,000 $       50,000 $                - $        750,000

Vancouver, Canada - $                 $                    - $                - $                - $                   -

Warren AFB Spill Site 7, WY - $                 $      2,200,000 $     150,000 $                - $     2,350,000

London, Ontario - $                 $           23,700 $         3,000 $                - $          26,700

Moffett, Full-Scale Est. 175,000 $      $      4,572,122 $                - $                - $     4,747,122

Dover, AFB Full-Scale Est. 150,000 $      $         520,000 $                - $                - $        670,000

Figure 5. Capital costs of the PRB sites.

Table 7. PRB Site Capital Cost Summary

$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 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

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.

Sites

Capital Cost
14

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 fullscale. 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 upgradient face, 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). For a 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 four 4ft-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.

1

 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.
15

Site

Annual PRB

O&M

PRB Stated

Fe

Maintenance

ETI Original

Fe

Maintenance

Calc.

ETI Jetting Fe

Maintenance

Calc.

ETI Auger

Agitation Fe

Maintenance

Calc.

ETI Ultrasound

or Pressure Fe

Maintenance

Calc.

USCG Support Center 85,000 $             $                     - $             60,000 $            32,832 $               36,480 $                63,840

Intersil Site 95,000 $             $           232,000 $             34,000 $              4,536 $                 5,040 $                 8,820

Watervliet Arsenal - $                      $                     - $             26,208 $            25,200 $               28,000 $                49,000

Moffett Federal Airfield 90,000 $             $                     - $              7,875 $              2,250 $                 2,500 $                 4,375

Somersworth Landfill SF

Site - $                      $                     - $           360,000 $          288,000 $             320,000 $              560,000

Dover AFB, DE - $                      $                     - $              9,400 $              2,808 $                 3,120 $                 5,460

Kansas City Plant, MO - $                      $                     - $                     - $            35,100 $               39,000 $                68,250

Aircraft Maintenance,

OR 50,000 $             $                     - $                     - $            26,100 $               29,000 $                50,750

Caldwell Trucking, NJ - $                      $                     - $                     - $            81,000 $               90,000 $              157,500

Former Manufacturing,

Fairfield, NJ 25,000 $             $                     - $           107,700 $            28,575 $               31,750 $                55,563

Industrial Site,

Coffeyville, KS - $                      $                     - $                     - $              1,980 $                 2,200 $                 3,850

Industrial Site, NY - $                      $                     - $                     - $            59,940 $               66,600 $              116,550

Industrial Site, SC - $                      $                     - $                     - $            84,825 $               94,250 $              164,938

Nickel Rim, Ontario 30,000 $             $                     - $              4,500 $              6,300 $                 7,000 $                12,250

Cape Canaveral, FL - $                      $                     - $                     - $            56,700 $               63,000 $              110,250

MMR CS-10 Plume, MA - $                      $                     - $                     - $            43,200 $               48,000 $                84,000

Pease AFB, NH 35,000 $             $                     - $                     - $            44,550 $               49,500 $                86,625

Vancouver, Canada - $                      $                     - $                     - $              5,643 $                 6,270 $                10,973

Warren AFB Spill Site 7,

WY - $                      $                     - $                     - $            76,680 $               85,200 $              149,100

London, Ontario 3,000 $               $                     - $              2,400 $                     - $                        - $                        -

Moffett, Full-Scale Est. 72,278 $             $           267,538 $           176,260 $            63,180 $               70,200 $              122,850

Dover, AFB Full-Scale

Est. 148,000 $           $           421,000 $              9,600 $              5,616 $                 6,240 $                10,920

Table 8. O&M Costs for the PRB Sites

6. Economic Data for the Pump-and-Treat Sites

6.1. P&T at the PRB sites

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 case 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 other sites

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.
16

Table 9. PRB Information Relevant to Maintenance Costs

Site

Reactive

Material

Mass,

Tons PRB Type

Reactive

Media Cost

Total

PRB

Length,

ft

Ave.

PRB

Depth,

ft

Total

PRB

Surface

Area,

ft^2

Total

Reactive

Media

Length,

ft

Ave.

Reactive

Media

Depth, ft

Reactive

Media

Face

Surface

Area,

ft^2

Ratio,

Media

SA to

PRB SA

USCG Support

Center Fe(0) 450 Trench $   200,000.00 152 24 3648 152 24 3648 1.000

Intersil Site Fe(0) 220 F&G $   170,000.00 40 20 800 36 14 504 0.630

Watervliet Arsenal Fe(0) 165.5 Trench $     87,360.00 190 10 1900 280 10 2800 1.474

Moffett Federal

Airfield Fe(0) 75 F&G $     39,375.00 50 25 1250 10 25 250 0.200

Somersworth

Landfill SF Site Fe(0) 3552 Trench $ 1,200,000.00 800 40 32000 800 40 32000 1.000

Dover AFB, DE Fe(0) 59 F&G $     47,000.00 68 39 2652 8 39 312 0.118

Kansas City Plant,

MO Fe(0) 650 Trench $                -    130 30 3900 130 30 3900 1.000

Aircraft

Maintenance, OR Fe(0) 324 F&G $                -    650 29 18850 100 29 2900 0.154

Caldwell Trucking,

NJ Fe(0) 250

Hydr.

Frac./Per

m. Infill

$                -    180 50 9000 180 50 9000 1.000

Former

Manufacturing,

Fairfield, NJ

Fe(0) 720 Trench $   359,000.00 127 25 3175 127 25 3175 1.000

Industrial Site,

Coffeyville, KS Fe(0) 70 F&G $     50,000.00 1020 30 30600 20 11 220 0.007

Industrial Site, NY Fe(0) 742 Trench $   358,000.00 370 18 6660 370 18 6660 1.000

Industrial Site, SC Fe(0) 400 Trench $   133,000.00 325 29 9425 325 29 9425 1.000

Nickel Rim,

Ontario

Organic

Matter 425 Trench $     15,000.00 50 14 700 50 14 700 1.000

Cape Canaveral,

FL Fe(0) 205 Trench $                -    100 45 4500 140 45 6300 1.400

MMR CS-10

Plume, MA Fe(0) 49

Hydr.

Frac./Per

m. Infill

$                -    48 100 4800 48 100 4800 1.000

Pease AFB, NH Fe(0) 360 Trench $                -    150 33 4950 150 33 4950 1.000

Vancouver, Canada Organic

Matter 0 Trench $                -    33 19 627 33 19 627 1.000

Warren AFB Spill

Site 7, WY Fe(0) 1750 Trench $   600,000.00 568 15 8520 568 15 8520 1.000

London, Ontario

Oxygen

furnace

slag

400 Trench $       8,000.00 0 0 0 0 0 0 NA

Moffett, Full-Scale

Est. Fe(0) 2518 F&G $   881,300.00 1100 45 49500 135 52 7020 0.142

Dover, AFB FullScale Est. Fe(0) 108 F&G $     48,000.00 136 39 5304 16 39 624 0.118
17

Site On-Site P&T

P&T

Construction

Cost

Annual P&T

O&M

USCG Support Center Estimated 500,000 $               $           200,000

Intersil Site Yes 325,000 $               $           142,158

Watervliet Arsenal Estimated 834,000 $               $                     -

Moffett Federal Airfield 0 - $                         $                     -

Somersworth Landfill SF Site Estimated 26,000,000 $          $        3,400,000

Dover AFB, DE 0 - $                         $                     -

Kansas City Plant, MO Yes - $                         $           200,000

Aircraft Maintenance, OR No - $                         $                     -

Caldwell Trucking, NJ ND - $                         $                     -

Former Manufacturing,

Fairfield, NJ Estimated 350,000 $               $             98,000

Industrial Site, Coffeyville, KS ND - $                         $                     -

Industrial Site, NY Estimated - $                         $           300,000

Industrial Site, SC ND - $                         $                     -

Nickel Rim, Ontario No - $                         $                     -

Cape Canaveral, FL ND - $                         $                     -

MMR CS-10 Plume, MA ND - $                         $                     -

Pease AFB, NH ND - $                         $                     -

Vancouver, Canada ND - $                         $                     -

Warren AFB Spill Site 7, WY ND - $                         $                     -

London, Ontario ND - $                         $                     -

Moffett, Full-Scale Est. Estimated 1,400,000 $            $           695,000

Dover, AFB Full-Scale Est. Estimated 502,000 $               $           219,833

Site

P&T

Construction

Cost

Calc. PRB

Construction

Cost

P&T

Construction

Minus PRB

Construction

Annual P&T

O&M

Annual PRB

O&M

Annual P&T

Minus PRB

O&M

USCG Support Center 500,000 $             $            500,000 $                     - $          200,000 $            85,000 $         115,000

Intersil Site 325,000 $             $            656,000 $          (331,000) $          142,158 $            95,000 $           47,158

Watervliet Arsenal 834,000 $             $            274,000 $           560,000 $                     - $                    - $                    -

Moffett Federal Airfield - $                        $            377,375 $                     - $                     - $            90,000 $                    -

Somersworth Landfill SF Site 26,000,000 $         $         2,100,000 $      23,900,000 $       3,400,000 $                    - $                    -

Dover AFB, DE - $                        $            358,000 $                     - $                     - $                    - $                    -

Kansas City Plant, MO - $                        $         1,240,000 $                     - $          200,000 $                    - $                    -

Aircraft Maintenance, OR - $                        $            700,000 $                     - $                     - $            50,000 $                    -

Caldwell Trucking, NJ - $                        $                      - $                     - $                     - $                    - $                    -

Former Manufacturing,

Fairfield, NJ 350,000 $             $            725,000 $          (375,000) $            98,000 $            25,000 $           73,000

Industrial Site, Coffeyville, KS - $                        $            400,000 $                     - $                     - $                    - $                    -

Industrial Site, NY - $                        $         1,000,000 $                     - $          300,000 $                    - $                    -

Industrial Site, SC - $                        $            356,000 $                     - $                     - $                    - $                    -

Nickel Rim, Ontario - $                        $              35,000 $                     - $                     - $            30,000 $                    -

Cape Canaveral, FL - $                        $            729,250 $                     - $                     - $                    - $                    -

MMR CS-10 Plume, MA - $                        $                      - $                     - $                     - $                    - $                    -

Pease AFB, NH - $                        $            550,000 $                     - $                     - $            35,000 $                    -

Vancouver, Canada - $                        $                      - $                     - $                     - $                    - $                    -

Warren AFB Spill Site 7, WY - $                        $         2,350,000 $                     - $                     - $                    - $                    -

London, Ontario - $                        $              26,700 $                     - $                     - $             3,000 $                    -

Moffett, Full-Scale Est. 1,400,000 $          $         4,618,122 $       (3,218,122) $          695,000 $            72,278 $         622,722

Dover, AFB Full-Scale Est. 502,000 $             $            582,000 $            (80,000) $          219,833 $          148,000 $           71,833

Table 10. P&T Information for the PRB Sites

Table 11. Comparison of P&T Costs Versus PRB Costs
18

$3,400,000

$0 $250,000 $500,000 $750,000 $1,000,000

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

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.

Sites

Cost

Annual P&T O&M

Annual PRB O&M

$26,000,000.00

$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 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

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.

Sites

Construction Cost

Calc. PRB Construction Cost

P&T Construction Cost

Somersworth P&T cost includes large-scale impermeable cap

Figure 6. PRB construction costs versus P&T construction costs at the PRB sites.

Figure 7. PRB O&M costs versus P&T O&M costs at the PRB sites.
19

7. Cost Comparison of PRB versus P&T Technologies

7.1. Rationale and approach

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 ($/1000 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. PRB cost per 1000 gallons of treated water

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 uncontaminated water is being drawn into the system and being treated as though contaminated (which it has become during the mixing).
20

Site

Total PRB

Surface

Area, ft^2

GW Flow

Velocity,

ft/d

PRB

Capture

Factor 1

Factor 1

GW Volume,

gal/yr

PRB

Capture

Factor 2

Factor 2

GW Volume,

gal/yr

USCG Support Center 3648 0.4 6.67E-01 2.66E+06 1 3.98E+06

Intersil Site 800 0.8 6.67E-01 1.16E+06 1 1.75E+06

Watervliet Arsenal 1900 0.15 6.67E-01 5.19E+05 1 7.78E+05

Moffett Federal Airfield 1250 0.35 6.67E-01 7.96E+05 1 1.19E+06

Somersworth Landfill SF Site 32000 1.25 6.67E-01 7.28E+07 1 1.09E+08

Dover AFB, DE 2652 0.18 6.67E-01 8.69E+05 1 1.30E+06

Kansas City Plant, MO 3900 0.59 6.67E-01 4.19E+06 1 6.28E+06

Aircraft Maintenance, OR 18850 0.3 6.67E-01 1.03E+07 1 1.54E+07

Caldwell Trucking, NJ 9000 1.1 6.67E-01 1.80E+07 1 2.70E+07

Former Manufacturing, Fairfield, NJ 3175 0.6 6.67E-01 3.47E+06 1 5.20E+06

Industrial Site, Coffeyville, KS 30600 0.6 6.67E-01 3.34E+07 1 5.01E+07

Industrial Site, NY 6660 0.6 6.67E-01 7.27E+06 1 1.09E+07

Industrial Site, SC 9425 0.14 6.67E-01 2.40E+06 1 3.60E+06

Nickel Rim, Ontario 700 0.13 6.67E-01 1.66E+05 1 2.48E+05

Cape Canaveral, FL 4500 0.05 6.67E-01 4.10E+05 1 6.14E+05

MMR CS-10 Plume, MA 4800 1 6.67E-01 8.74E+06 1 1.31E+07

Pease AFB, NH 4950 0 6.67E-01 0.00E+00 1 0.00E+00

Vancouver, Canada 627 0 6.67E-01 0.00E+00 1 0.00E+00

Warren AFB Spill Site 7, WY 8520 0.9 6.67E-01 1.40E+07 1 2.09E+07

London, Ontario 0 0 6.67E-01 0.00E+00 1 0.00E+00

Moffett, Full-Scale Est. 49500 0.35 6.67E-01 3.15E+07 1 4.73E+07

Dover, AFB Full-Scale Est. 5304 0.18 6.67E-01 1.74E+06 1 2.61E+06

Table 12. Ground-water Flow and Volume Data Relevant to a Unit Cost Evaluation

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.
21

Table 13. Present Value Calculation for Annual PRB Site O&M Costs, Including 30-year Total as Present Value

Year

USCG Support

Center Intersil Site

Moffett

Federal

Airfield

Aircraft

Maintenance,

OR

Former

Manufacturing,

Fairfield, NJ

Nickel Rim,

Ontario

Pease AFB,

NH

London,

Ontario

Moffett, FullScale Est.Dover, AFB FullScale Est.

0 85,000.00 $       $       95,000.00 $      90,000.00 $    50,000.00 $       25,000.00 $   30,000.00 $   35,000.00 $    3,000.00 $       72,278.00 $      148,000.00

1 81,730.77 $       $       91,346.15 $      86,538.46 $    48,076.92 $       24,038.46 $   28,846.15 $   33,653.85 $    2,884.62 $       69,498.08 $      142,307.69

2 78,587.28 $       $       87,832.84 $      83,210.06 $    46,227.81 $       23,113.91 $   27,736.69 $   32,359.47 $    2,773.67 $       66,825.07 $      136,834.32

3 75,564.69 $       $       84,454.65 $      80,009.67 $    44,449.82 $       22,224.91 $   26,669.89 $   31,114.87 $    2,666.99 $       64,254.88 $      131,571.46

4 72,658.36 $       $       81,206.40 $      76,932.38 $    42,740.21 $       21,370.10 $   25,644.13 $   29,918.15 $    2,564.41 $       61,783.54 $      126,511.02

5 69,863.80 $       $       78,083.08 $      73,973.44 $    41,096.36 $       20,548.18 $   24,657.81 $   28,767.45 $    2,465.78 $       59,407.25 $      121,645.21

6 67,176.73 $       $       75,079.88 $      71,128.31 $    39,515.73 $       19,757.86 $   23,709.44 $   27,661.01 $    2,370.94 $       57,122.35 $      116,966.55

7 64,593.01 $       $       72,192.19 $      68,392.60 $    37,995.89 $       18,997.95 $   22,797.53 $   26,597.12 $    2,279.75 $       54,925.34 $      112,467.84

8 62,108.67 $       $       69,415.57 $      65,762.12 $    36,534.51 $       18,267.26 $   21,920.71 $   25,574.16 $    2,192.07 $       52,812.83 $      108,142.15

9 59,719.87 $       $       66,745.74 $      63,232.81 $    35,129.34 $       17,564.67 $   21,077.60 $   24,590.54 $    2,107.76 $       50,781.56 $      103,982.84

10 57,422.95 $       $       64,178.60 $      60,800.78 $    33,778.21 $       16,889.10 $   20,266.93 $   23,644.75 $    2,026.69 $       48,828.43 $        99,983.50

11 55,214.38 $       $       61,710.19 $      58,462.28 $    32,479.05 $       16,239.52 $   19,487.43 $   22,735.33 $    1,948.74 $       46,950.41 $        96,137.98

12 53,090.75 $       $       59,336.72 $      56,213.73 $    31,229.85 $       15,614.93 $   18,737.91 $   21,860.90 $    1,873.79 $       45,144.63 $        92,440.36

13 51,048.80 $       $       57,054.54 $      54,051.67 $    30,028.70 $       15,014.35 $   18,017.22 $   21,020.09 $    1,801.72 $       43,408.29 $        88,884.96

14 49,085.38 $       $       54,860.13 $      51,972.76 $    28,873.75 $       14,436.88 $   17,324.25 $   20,211.63 $    1,732.43 $       41,738.74 $        85,466.31

15 47,197.48 $       $       52,750.13 $      49,973.81 $    27,763.23 $       13,881.61 $   16,657.94 $   19,434.26 $    1,665.79 $       40,133.41 $        82,179.15

16 45,382.19 $       $       50,721.28 $      48,051.74 $    26,695.41 $       13,347.70 $   16,017.25 $   18,686.79 $    1,601.72 $       38,589.82 $        79,018.41

17 43,636.73 $       $       48,770.46 $      46,203.59 $    25,668.66 $       12,834.33 $   15,401.20 $   17,968.06 $    1,540.12 $       37,105.59 $        75,979.24

18 41,958.39 $       $       46,894.67 $      44,426.53 $    24,681.41 $       12,340.70 $   14,808.84 $   17,276.98 $    1,480.88 $       35,678.45 $        73,056.96

19 40,344.61 $       $       45,091.03 $      42,717.82 $    23,732.12 $       11,866.06 $   14,239.27 $   16,612.48 $    1,423.93 $       34,306.21 $        70,247.08

20 38,792.89 $       $       43,356.76 $      41,074.83 $    22,819.35 $       11,409.67 $   13,691.61 $   15,973.54 $    1,369.16 $       32,986.74 $        67,545.27

21 37,300.86 $       $       41,689.19 $      39,495.02 $    21,941.68 $       10,970.84 $   13,165.01 $   15,359.18 $    1,316.50 $       31,718.02 $        64,947.37

22 35,866.21 $       $       40,085.76 $      37,975.98 $    21,097.77 $       10,548.88 $   12,658.66 $   14,768.44 $    1,265.87 $       30,498.09 $        62,449.40

23 34,486.74 $       $       38,544.00 $      36,515.37 $    20,286.32 $       10,143.16 $   12,171.79 $   14,200.42 $    1,217.18 $       29,325.09 $        60,047.50

24 33,160.33 $       $       37,061.54 $      35,110.93 $    19,506.07 $         9,753.04 $   11,703.64 $   13,654.25 $    1,170.36 $       28,197.20 $        57,737.98

25 31,884.93 $       $       35,636.10 $      33,760.51 $    18,755.84 $         9,377.92 $   11,253.50 $   13,129.09 $    1,125.35 $       27,112.69 $        55,517.29

26 30,658.58 $       $       34,265.48 $      32,462.03 $    18,034.46 $         9,017.23 $   10,820.68 $   12,624.12 $    1,082.07 $       26,069.90 $        53,382.01

27 29,479.41 $       $       32,947.57 $      31,213.49 $    17,340.83 $         8,670.41 $   10,404.50 $   12,138.58 $    1,040.45 $       25,067.21 $        51,328.85

28 28,345.59 $       $       31,680.36 $      30,012.97 $    16,673.87 $         8,336.94 $   10,004.32 $   11,671.71 $    1,000.43 $       24,103.08 $        49,354.67

29 27,255.37 $       $       30,461.88 $      28,858.63 $    16,032.57 $         8,016.29 $     9,619.54 $   11,222.80 $       961.95 $       23,176.04 $        47,456.41

30 26,207.09 $       $       29,290.27 $      27,748.68 $    15,415.93 $         7,707.97 $     9,249.56 $   10,791.15 $       924.96 $       22,284.66 $        45,631.16

Total 30

Yr

Annual

O&M PV

$1,554,822.83 $  1,737,743.16 $ 1,646,283.00 $  914,601.67 $     457,300.83 $ 548,761.00 $ 640,221.17 $  54,876.10 $  1,322,111.58 $   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 + PVannual costs (1)

The capital cost is incurred in the present, whereas the PVannual costs occurs both in the present and in the future. The

PVannual costs is calculated as

= ( ) = +

∑

n

i

annual cos ts i

i 0

Y PV

1 r (2)

where: i is the year

Yi 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.
22

Site

Total 30 Yr

Annual

O&M PV

Calc. PRB

Construction

Cost

30 Yr Total

O&M +

Construction

Factor 1 (0.67),

GW 1000 Gal

per 30 Yrs

30 Yr O&M

Cost per

1000 Gal

30 Yr

Construction

Cost per 1000

Gal

30 Yr O&M +

Construction

Cost per 1000

Gal

USCG Support Center $1.55E+06 $5.00E+05 $2.05E+06 7.97E+04 $           19.51   $                6.27   $              25.79

Intersil Site $1.74E+06 $6.56E+05 $2.39E+06 3.49E+04 $           49.72   $              18.77   $              68.49

Moffett Federal Airfield $1.65E+06 $3.77E+05 $2.02E+06 2.39E+04 $           68.91   $              15.80   $              84.71

Aircraft Maintenance, OR $9.15E+05 $7.00E+05 $1.61E+06 3.09E+05 $             2.96   $                2.27   $                5.23

Former Manufacturing,

Fairfield, NJ $4.57E+05 $7.25E+05 $1.18E+06 1.04E+05 $             4.40   $                6.97   $              11.37

Nickel Rim, Ontario $5.49E+05 $3.50E+04 $5.84E+05 4.97E+03 $         110.43   $                7.04   $            117.47

Moffett, Full-Scale Est. $1.32E+06 $4.62E+06 $5.94E+06 9.46E+05 $             1.40   $                4.88   $                6.28

Dover, AFB Full-Scale Est. $2.71E+06 $5.82E+05 $3.29E+06 5.21E+04 $           51.93   $              11.16   $              63.09

Sites with Fe

Maintenance Estimates

(A) Fe

Maint. 30 Yr

PV (10 yr

cycle)

(B) Fe Maint.

30 Yr PV + 30

Yr O&M PV

(A) + (B) +

Calc. PRB

Construction

Cost

Total PV Cost

per 1000 Gal

over 30 Years

Intersil Site + Fe Maint. $4.95E+05 $2.23E+06 $3.38E+06 $                96.80

Moffett, Full-Scale Est. + Fe

Maint. $5.70E+05 $1.89E+06 $7.08E+06 $                  7.48

Dover, AFB Full-Scale Est.

+ Fe Maint. $8.98E+05 $3.60E+06 $5.08E+06 $                97.52

Table 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)

The total O&M PV costs are carried into Table 14 for the 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 PV cost 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 water that

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/yr for U.S. EPA, 1999a) was offset by the differences in estimates of annual ground-water volume (796,000 gallons 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.
23

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.

Site

Factor 1

(0.67), GW

1000 Gal

per Yr

Construction

Cost per 1000

Gal

Current Year

O&M Cost

per 1000 Gal

Capital Cost per

1000 Gal GW

Treated Per Year

(U.S. EPA, 1999a)

Avg. Annual O&M  

Cost per 1000 Gal

GW Treated per

Year (U.S. EPA,

1999a)

USCG Support Center 2.66E+03 188 $                    $                  32 $                       190 $                         33

Intersil Site 1.16E+03 563 $                    $                  82 $                       520 $                         83

Moffett Federal Airfield 7.96E+02 474 $                    $                113 $                    1,600 $                       110

Aircraft Maintenance, OR 1.03E+04 68 $                      $                   5

Former Manufacturing, Fairfield, NJ 3.47E+03 209 $                    $                   7

Nickel Rim, Ontario 1.66E+02 211 $                    $                181

Moffett, Full-Scale Est. 3.15E+04 146 $                    $                   2

Dover, AFB Full-Scale Est. 1.74E+03 335 $                    $                  85

Table 15. Costs per 1000 Gallons Treated by PRB During a Single or Average Year, Including Data from U.S. EPA,

1999a

7.3. P&T costs per 1000 gallons of treated water

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, per the 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. Comparison of P&T and PRB unit costs at the PRB sites

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, for the 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.
24

Site Type

Avg. Annual

O&M Cost

(U.S. EPA,

1999a)

1000 Gallons of

GW Treated per Yr

(U.S. EPA, 1999a)

Annual O&M per

1000  Gal (U.S.

EPA, 1999a)

Annual O&M per

1000 Gal at Moffett

PRB GW Volume

Libby P&T 500,000 $            2900 170 $                        $                           2,500

Old Mill P&T 210,000 $            1700 130 $                        $                           1,050

Moffett PRB 26,000 $             200 110 $                        $                             130

City Industries P&T 170,000 $            50000 97 $                         $                             850

Site Type

Avg. Annual

O&M Cost

(U.S. EPA,

1999a)

1000 Gallons of

GW Treated per Yr

(U.S. EPA, 1999a)

Annual O&M per

1000  Gal (U.S.

EPA, 1999a)

Annual O&M per

1000 Gal at Intersil

PRB GW Volume

Intersil P&T 140,000 $            5000 28 $                         $                             127

Intersil PRB 95,000 $             1100 83 $                         $                               86

Site

Factor 1

GW

Volume,

1000 Gal/Yr

A. PRB

Construction

Cost per

1000 Gal

B. P&T

Construction

Cost per

1000 Gal

A - B

Construction

Costs per

1000 Gal

C. Current

Year

(Annual)

PRB O&M

Cost per

1000 Gal

D. Current

Year

(Annual)  

P&T O&M

Cost per

1000 Gal

C-D Current

Year

(Annual)

O&M Costs

per 1000 Gal

USCG Support Center 2.66E+03 188 $                $               188 $                    - $                 32 $              75 $                (43)

Intersil Site 1.16E+03 563 $                $               279 $               284 $                 82 $            122 $                (40)

Watervliet Arsenal 5.19E+02 528 $                $            1,608 $            (1,079) $                   - $                - NA

Moffett Federal Airfield 7.96E+02 474 $                $                   - NA 113 $                $                - NA

Somersworth Landfill SF Site 7.28E+04 29 $                  $               357 $              (328) $                   - $              47 NA

Dover AFB, DE 8.69E+02 412 $                $                   - NA - $                    $                - NA

Kansas City Plant, MO 4.19E+03 296 $                $                   - NA - $                    $              48 NA

Aircraft Maintenance, OR 1.03E+04 68 $                  $                   - NA 5 $                   $                - NA

Caldwell Trucking, NJ 1.80E+04 - $                    $                   - NA - $                    $                - NA

Former Manufacturing, Fairfield,

NJ 3.47E+03 209 $                $               101 $               108 $                  7 $              28 $                (21)

Industrial Site, Coffeyville, KS 3.34E+04 12 $                  $                   - NA - $                    $                - NA

Industrial Site, NY 7.27E+03 137 $                $                   - NA - $                    $              41 NA

Industrial Site, SC 2.40E+03 148 $                $                   - NA - $                    $                - NA

Nickel Rim, Ontario 1.66E+02 211 $                $                   - NA 181 $                $                - NA

Cape Canaveral, FL 4.10E+02 1,781 $             $                   - NA - $                    $                - NA

MMR CS-10 Plume, MA 8.74E+03 - $                    $                   - NA - $                    $                - NA

Pease AFB, NH 0.00E+00 NA NA NA NA NA NA

Vancouver, Canada 0.00E+00 NA NA NA NA NA NA

Warren AFB Spill Site 7, WY 1.40E+04 168 $                $                   - NA - $                    $                - NA

London, Ontario 0.00E+00 NA NA NA NA NA NA

Moffett, Full-Scale Est. 3.15E+04 146 $                $                44 $               102 $                  2 $              22 $                (20)

Dover, AFB Full-Scale Est. 1.74E+03 335 $                $               289 $                 46 $                 85 $            126 $                (41)

Table 16. Evaluation of Reported O&M Unit Costs for Four Sites by Modifying the Unit Basis

Table 17. Evaluation of Reported P&T Versus PRB Unit Costs at the Intersil Site by Modifying the Unit Basis

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
25

8. Summary and 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 costeffectiveness 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 costcomparison 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.
26

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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.

EPA 542-R-00-013.
27

Appendix A

Example Contact Questionnaire

Site Name:

Contact:

General Cost and

Site Information

Reactive Barrier Information:

Barrier Type (Circle or Select)

| Funnel & Gate | Trench | Container | Other |

Reactive Material (e.g., Fe0

)

Reactive Material Mass, Tons

Treated Contaminants (TCE, etc.)

Scale (Full or Pilot)

Contam Conc Maxima in μg/L

Est Total Plume Volume, L

Est. Plume Contam. Mass, Kg

Separate Source Treatment? | Yes | No |

TOTAL PRB Cost> $

PRB Treatment Unit Cost

(e.g., $/lb TCE treated; $1000/lb TCE)

$

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:

 Specific PRB Cost and

Site Information

Site 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:

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:
28

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:

Other O&M Costs

Other Annual O&M Costs $

Describe Other O&M Costs:

Post Installation (PI) PRB Modifications?

| Yes | No |

PI PRB Cost $

Why Were PI PRB Mods Made?

Additional Plume Treatments Required?

| Yes | No |

Additional Treatment Cost/Year $

Why Were Additional Treatments Needed

TOTAL Annual O&M Costs> $

O&M Notes:

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:

Licensing and Reports

PRB License Fee $

Funnel/Gate License Fee $

Other License Cost $

Design/Construction Report Costs $

Annual License Renewal $

TOTAL Initial Lic. & Report Costs > $

Licenses & Reports Notes:
29

Appendix 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.

Aircraft Maintenance Facility, OR

David Weymann, P.E., PSS

The IT Group

15055 SW Sequoia Parkway, Suite 1400

Portland, OR 97224

Tel: (503) 624-7200 ext 543

Fax: (503) 624-7200

dweymann@theitgroup.com

Cape Canaveral

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

Fairfield

Stephen Tappert

TRC VECTRE Corporation

333 Route 46 West

Suite 202

Mountain Lakes, NJ 07046

Tel: (973) 402-9900

Fax: (973) 402-4656

STappert@trcsolutions.com

Industrial Site, SC

Steven Schroeder

RMT, Inc.

100 Verdae Blvd.,

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

Kansas 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
30

Moffett AFB

Arun Gavaskar

Battelle Memorial Institute

505 King Avenue

Columbus, OH 43201

Tel: (614) 424-3403

Fax: (614) 424-3667

gavaskar@battelle.org

Nickel Rim, Ontario

David Blowes

Waterloo Centre For Groundwater Research

University Of Waterloo

Waterloo, ONTARIO

Tel: (519) 888-4878

Fax: (519) 746-5644

blowes@sciborg.uwaterloo.ca

Pease AFB

Jeffrey Cange

Bechtel Environmental

151 Layfayette Drive

P.O. Box 3500

Oak Ridge, TN 37831-0350

Tel: (423) 220-2255

Fax: (423) 220-2108

jbcange@bechtel.com

Somersworth Landfill

Roger Duwart

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 Support Center, Elizabeth 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, Canada

Eric Pringle

Hemmera Envirochem Inc.

Suite 350, 1190 Hornby Street

Vancouver, British Columbia V6Z 2K5, Canada

Tel: (604) 669-0424

Fax: (604) 669-0430

eric.pringle@conorpacific.com

Warren AFB

Michael May

URS Greiner

4582 South Ulster Street

Denver, CO 80237-2637

Tel: (303) 740-3863

michael_may@urscorp.com

Watervliet Arsenal

Russell Marsh

US Army Corps Of Engineers

P.O. Box 1715

Baltimore, MD 21203

Tel: (410) 962-2227

Fax: (410) 962-2318

russell.e.marsh@usace.army.mil
31
2

United States

Environmental Protection

Agency

EPA/600/R-02/034

June 2002

National Risk Management

 Research Laboratory

Cincinnati, OH 45268

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