vvEPA
United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPA/540/R-98/501
September 1998
www.epa.gov/ORD/SITE
EnviroMetal Technologies,
Inc., Metal-Enhanced
Dechlorination of Volatile
Organic Compounds
Using an In-Situ Reactive
Iron Wall
Innovative Technology
Evaluation Report
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
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EPA/540/R-98/501
September 1998
EnviroMetal Technologies, Inc.
Metal-Enhanced Dechlorination of
Volatile Organic Compounds
Using an In-Situ Reactive Iron Wall
Innovative Technology Evaluation Report
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
Printed on Recycled Paper
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Notice
The information in this document has been funded by the U. S. Environmental Protection Agency (EPA) under Contract No. 68-
C5-0037 to Tetra Tech EM Inc. (formerly PRC Environmental Management, Inc.). It has been subjected to the Agency's peer
and administrative reviews and has been approved for publication as an EPA document. Mention of trade names or commercial
products does not constitute an endorsement or recommendation for use.
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Foreword
The U. S. Environmental Protection Agency (EPA) 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 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 is the Agency's center for investigation of technological and manage-
ment approaches for reducing risks from threats to human health and the environment. The focus of the Laboratory's research
program is on methods for the prevention and control of pollution to air, land, water and subsurface resources; protection of
water quality in public water systems; remediation of contaminated sites and groundwater; and prevention and control of
indoor air pollution. The goal of this research effort is to catalyze development and implementation of innovative, cost-
effective environmental technologies; develop scientific and engineering information needed by EPA to support regulatory and
policy decisions; and provide technical support and information transfer to ensure effective implementation of environmental
regulations and strategies.
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.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
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Abstract
EnviroMetal Technologies, Inc. (EH), of Guelph, Ontario, Canada has commercialized a metal-enhanced dechlorination
technology that the University of Waterloo, Canada developed to treat aqueous media contaminated with chlorinated volatile
organic compounds (VOCs). The technology employs an electrochemical process that involves the oxidation of a reactive,
granular iron medium to induce reductive dechlorination of chlorinated VOCs.
The Supcrfund Innovative Technology Evaluation (SITE) Program evaluated an in-situ application of the technology during a
6-month demonstration at a confidential site in central New York in 1995. For the demonstration of the in-situ system, the
technology was constructed as a subsurface, reactive iron wall that fully penetrated a shallow sand and gravel aquifer. The top
of the wall was above the highest average seasonal groundwater level, about 3 feet below grade, and was covered with a layer
of native topsoil. The wall extended downward from (he top of the saturated zone and was situated on top of an underlying,
confining clay layer. The reactive iron wall, referred to as the "gate," was oriented perpendicular to the groundwater flow
direction and was flanked by impermeable sheet piling wings which also fully penetrated the aquifer. The sheet piling formed
a "funnel," creating a hydraulic barrier that diverted groundwater flow from a 24-foot-wide upgradient area through the gate,
and prevented untreated groundwater from flowing around the gate and mixing with treated groundwater on the downgradient
side.
During the demonstration, SITE Program personnel collected independent data to evaluate the technology's performance with
respect to primary and secondary objectives. Groundwater samples were collected at locations on the upgradient (influent)
and downgradient (effluent) sides of the iron, and also from locations within the iron. The groundwater samples were analyzed
for VOCs to evaluate the technology's ability to reduce chlorinated VOC concentrations to applicable regulatory levels. The
efficiency with which the system removed certain chlorinated VOCs was evaluated. Other data were collected to provide
information about the dechlorination process, as well as costs and operating and maintenance requirements for the system.
The results of the sample analyses indicated that the technology significantly reduced the concentrations of chlorinated VOCs
in groundwater passing through the gate. These chlorinated VOCs included trichloroethene (TCE), cis-l,2-dichloroethene
(cDCE), and vinyl chloride (VC). All average critical parameter effluent concentrations, and 86 out of 90 individual critical
parameter measurements, achieved the applicable U.S. Environmental Protection Agency (EPA) maximum contaminant levels
or New York State Department of Environmental Conservation target standards. Removal efficiencies for TCE, cDCE, and
VC were consistently greater than 90 percent. The results indicated no decrease in removal efficiency or other significant
changes in system performance over the 6-month demonstration period.
EPA SITE Program personnel prepared this Innovative Technology Evaluation Report (ITER) to present the results of the
SITE Program demonstration. The ITER evaluates the ability of the in-situ application of the metal-enhanced dechlorination
technology to treat chlorinated VOCs in contaminated groundwater based on the demonstration results. Specifically, this
report discusses performance and economic data collected by SITE Program personnel, and also presents case studies and
additional information about the technology provided by ETI.
IV
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Contents
List of Figures vm
List of Tables x
Acronyms, Abbreviations, and Symbols . xi
Conversion Factors xiv
Acknowledgments xv
Executive Summary 1
1 Introduction 6
1.1 Description of the SITE Program and Reports 6
1.1.1 Purpose, History, and Goals of the SITE Program 6
1.1.2 Documentation of SITE Demonstration Results 7
1.2 Background of the Metal-Enhanced Dechlorination Technology in the SITE Program 8
1.3 Technology Description 8
1.3.1 Process Chemistry 8
1.3.2 General Application and Design of Metal-Enhanced Process Systems 9
1.3.3 Advantages and Innovative Features of the Metal-Enhanced Dechloronation Process.. 10
1.4 Applicable Wastes ; 10
1.5 Overview of In-Situ, Metal-Enhanced Dechlorination Technology SITE Demonstration 12
1.5.1 Site Background r - 12
1.5.2 Technology Design 12
1.5.3 Technology and Monitoring System Construction 12
1.5.4 Treatment System Operation 16
1.5.5 SITE Demonstration Objectives 16
1.5.6 Demonstration Procedures 17
1.6 Postdemonstration Activities 18
1.7 Key Contacts 18
2 Technology Effectiveness Analysis 20
2.1 SITE Demonstration Results 20
2.1.1 Objective P-l: Compliance with Applicable Effluent Target Levels 23
2.1.2 Objective P-2: Critical Parameter Removal Efficiency 23
2.1.3 Objective S-l: Critical Parameter Concentrations as a Function of
Sampling Location (Distance) 25
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Contents (continued)
2.1.4 Objective S-2: Noncritical VOCs, Metals, and Other Inorganic Parameters 29
2.1.5 Objective S-3: Eh, DO, pH, Specific Conductivity, and Temperature 36
2.1.6 Objective S-4: Biological Microorganism Growth 40
2.1.7 Objective S-5: Operating and Design Parameters 40
2.2 Additional Performance Data 43
2.2.1 BordenSite 46
2.2.2 California Semiconductor Facility 46
2.2.3 Belfast, Northern Ireland Facility 46
3 Technology Applications Analysis 47
3.1 Factors Affecting Performance 47
3.1.1 Feed Waste Characteristics 47
3.1.2 Hydrogeologic Characteristics 48
3.1.3 Operating Parameters 49
3.1.4 Maintenance Requirements 50
3.2 Site Characterstics and Support Requkements 51
3.2.1 Site Access, Area, and Preparation Requirements 51
3.2.2 Climate Requirements 51
3.2.3 Utility and Supply Requirements 52
3.2.4 Required Support Systems 52
3.2.5 Personnel Requirements 52
3.3 Material Handling Requirements 52
3.4 Technology Limitations 53
3.5 Potential Regulatory Requirements 54
3.5.1 Comprehensive Environmental Response, Compensation, and Liability Act 54
3.5.2 Resource Conservation and Recovery Act 56
3.5.3 Clean Water Act 57
3.5.4 Safe Drinking Water Act 57
3.5.5 Clean Air Act 57
3.5.6 Mixed Waste Regulations 58
3.5.7 Occupational Safety and Health Administration 58
3.6 State and Community Acceptance 58
4 Economic Analysis 59
4.1 Factors Affecting Costs 62
4.2 Assumptions Used in Performing the Economic Analysis 62
4.3 Cost Categories 64
4.3.1 Site Preparation Costs 64
vi
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Contents (continued)
4.3.2 Permitting and Regulatory Costs 66
4.3.3 Mobilization and Startup Costs 66
4.3.4 Capital Equipment Costs 66
4.3.5 Labor Costs 67
4.3.6 Supply Costs 67
Utility Costs 67
Effluent Treatment and Disposal Costs 68
4.3.9 Residual Waste Shipping and Handling Costs
4.3.10 Analyutical Services Costs
4.3.11 Equipment Maintenance Costs
4.3.12 Site Demobilization Costs
4.3.7
4.3.8
68
68
68
69
4.4 Economic Analysis Summary 69
5 Technology Status and Implementation 7^
6 References 7"
Appendix
A Vendor's Claims for the Technology
B Case Studies
C Summary of Analytical Data from the Demonstration of the In-Situ Metal-Enhanced Dechlorination
Process: June 1995-December 1995
vii
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Figures
1-1 Site Demonstration Area Layout 14
1-2 Plan and Profile Views of Funnel and Gate 15
2-1 Critical VOC Removal Efficiency Over Time 25
2-2 Critical VOCs vs. Distance-June 26
2-3 Critical VOCs vs. Distance-July 26
2-4 Critical VOCs vs. Distance-August 27
2-5 Critical VOCs vs. Distance-October 27
2-6 Critical VOCs vs. Distance-November 28
2-7 Critical VOCs vs. Distance-December 28
2-8 Summary of Calcium Data Over Time 31
2-9 Summary of Magnesium Data Over Time 31
2-10 Average Calcium and Magnesium Values vs. Distance 31
2-11 Summary of Iron Data Over Time 32
2-12 Summary of Manganese Data Over Time 32
2-13 Average Iron and Manganese Values vs. Distance 32
2-14 Summary of Barium Data Over Time 34
2-15 Summary of Bicarbonate Alkalinity Data Over Time 34
2-16 Average Bicarbonate Alkalinity and pH vs. Distance 34
2-17 Summary of Sulfate Data Over Time 35
2-18 Summary of Total Nitrate/Nitrite Data Over Time 35
2-19 Average Sulfate and Total Nitrate/Nitrite Values vs. Distance 35
2-20 Summary of pH Data Over Time 37
2-21 Average pH Values vs. Distance 37
2-22 Summary of SpecificConductivity Data Over Time 38
2-23 Average Specific Conductivity Values vs. Distance 38
2-24 Average Groundwater Temperature in Iron Wells vs. Time 39
2-25 Summary of Eh Data Over Time 39
2-26 Average Eh Values vs. Distance 39
VIII
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Figures (continued)
2-27 Total Phospholipid Fatty Acids vs. Distance 41
2-28 Piezometric Elevations-December 1995 45
4-1 Distribution of Fixed Costs for Continuous Wall 71
4-2 Distribution of Annual Variable Costs for Continuous Wall 71
4-3 Distribution of Fixed Costs for Funnel and Gate System 72
4-4 Distribution of Annual Variable Costs for Funnel and Gate System 72
IX
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Tables
ES-l Superfund Feasibility Study Evaluation Criteria for the
Metal-Enhanced Dechloronation Technology 4
1-1 Correlation Between Superfund Feasibility Evaluation Criteria and ITER Sections 7
1-2 Comparison of Technologies for Treating Chlorinated VOCs in Water 11
1-3 System Design Criteria and Applicable Effluent Standards 13
2-1 Demonstration Results with Respect to Objectives 21
2-2 Summary of Critical VOC Concentrations at Effluent Sampling Locations 22
2-3 Summary of Critical Parameter Removal Efficiency: July-December 1995 24
2-4 Summary of Operating and Design Parameters 42
2-5 Piezometric Data 44
3-1 Summary of Environmental Regulations 55
4-1 Estimated Costs Associated with the Metal-Enhanced Dechloronation Technology:
Continuous Wall System 60
4-2 Estimated Costs Associated with the Metal-Enhanced Dechloronation Technology:
Funnel and Gate System 61
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Acronyms, Abbreviations, and Symbols
AEA
ARAR
BGS
CAA
CaC03
CERCLA
CFR
Cl
CO32
DCA
cDCE
CWA
1,2-DCE
DO
DOE
Eh
EPA
ETI
Fe
Fe(OH)2
Fe(OH)3
FeC03
ft
H+
H2(g)
HC0-
in
ITER
Atomic Energy Act
Applicable or Relevant and Appropriate Requirement
Below ground surface
Clean Air Act
Calcium carbonate
Comprehensive Environmental Response, Compensation, and Liability Act
Code of Federal Regulations
Chloride ion
Carbonate ion
1,1-Dichloroethane
cis-1,2-Dichloroethene
Clean Water Act
1,2-Dichloroethene (general; undifferentiated for cis- and trans- isomers)
Dissolved oxygen
Department of Energy
Oxidation-reduction potential
U.S. Environmental Protection Agency
EnviroMetal Technology, Inc.
Zero-valent iron
Ferrous iron
Ferric iron
Ferrous hydroxide
Ferric hydroxide
Ferrous carbonate or siderite
Feet
Gallons per day
Hydrogen ion
Hydrogen gas
Bicarbonate ion
Inch
Innovative Technology Evaluation Report
XI
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Acronyms, Abbreviations, and Symbols (continued)
LCL
LDR
m
MCL
MDL
mg/L
Mn02(s)
msl
NAPL
NESHAP
NOEL
NPDES
NRG
NRMRL
NSPS
NYSDEC
O&M
OH-
ORD
OSHA
OSWER
PCB
PCE
pcf
PLFA
POTW
ppbv
ppe
QAPP
QA/QC
RCRA
RE
SARA
SDWA
S&W
SITE
TCA
TCE
TCL
Lower confidence limit
Land disposal restrictions
Meter
Maximum contaminant level
Method detection limit
milligram per liter
Manganese dioxide (solid)
mean sea level
Nonaqueous-phase liquid
National Emission Standards for Hazardous Air Pollutants
Nonobservable Effect Level
National Pollutant Discharge Elimination System
Nuclear Regulatory Commission
National Risk Management Research Laboratory
New Source Performance Standard
New York State Department of Environmental Conservation
Operating and maintenance
Hydroxyl ion
U.S. EPA Office of Research and Development
Occupational Safety and Health Act
Office of Solid Waste and Emergency Response
Polychlorinated biphenyl
Tetrachloroethene
Pounds per cubic foot
Phospholipid fatty acid
Publicly Owned Treatment Works
Parts per billion by volume
Personnel protective equipment
Quality assurance project plan
Quality assurance/quality control
Resource Conservation and Recovery Act
Removal efficiency
Superfund Amendments and Reauthorization Act
Safe Drinking Water Act
Stearns & Wheler, L.L.C.
Superfund Innovative Technology Evaluation
1,1,1 -Trichloroethane
Trichloroethene
Target compound list
xii
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Acronyms, Abbreviations, and Symbols (continued)
TCLP
tDCE
TER
TIC
TSCA
vc
voc
WQS
Toxicity characteristic leaching procedure
Trans-1,2-Dichloroethene
Technology evaluation report
Tentatively identified compound
Toxic Substances Control Act
Micrograms per liter
Vinyl chloride
Volatile organic compound
Water quality standards
XIII
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Conversion Factors
To Convert From
To
Multiply By
Length
Area:
Volume:
inch
foot
mile
square foot
acre
gallon
cubic foot
centimeter
meter
kilometer
square meter
square meter
liter
cubic meter
2.54
0.305
1.61
0.0929
4,047
3.78
0.0283
Mass:
pound
kilogram
0.454
Energy:
kilowatt-hour
megajoule
3.60
Power:
kilowatt
horsepower
1.34
Temperature: ("Fahrenheit - 32) "Celsius
0.556
XIV
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Acknowledgments
This report was prepared for EPA's SITE Program by PRC Environmental Management, Inc. (PRC), a wholly owned
subsidiary of Terra Tech, Inc., under the direction and coordination of Dr. Chien T. Chen, U.S. Environmental Protection
Agency (EPA) Superfund Innovative Technology Evaluation (SITE) Program project manager in the National Risk Manage-
ment Research Laboratory (NRMRL), Edison, New Jersey. Contributors and reviewers for this report included Ms. Ann Kern,
Mr. Vince Gallardo and Mr. Thomas Holdsworth of EPA NRMRL, Cincinnati, Ohio.
Special acknowledgment is given to Mr. Robert Focht and Mr. John L. Vogan of EnviroMetal Technologies, Inc., Guelph,
Ontario, Canada; Ms. Diane Clark of Stearns & Wheler, L.L.C.; the site owners; and the New York Department of
Environmental Conservation for their cooperation and support during the SITE Program demonstration and during the
development of this report.
xv
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Executive Summary
EnviroMetal Technologies, Inc. (ETI), has commercialized
a metal-enhanced dechlorination technology originally
developed by the University of Waterloo, Canada to
dechlorinate chlorinated volatile organic compounds
(VOCs) such as chlorinated methanes, ethanes, and
ethenes in aqueous media. An in-situ application of the
technology was demonstrated under the U.S. Environmental
Protection Agency's (EPA) Superfund Innovative
Technology Evaluation (SITE) Program at a confidential
site in central New York state from June through
December 1995.
The purpose of this Innovative Technology Evaluation
Report is to present information that will assist Superfund
decision-makers in evaluating this technology's suitability
for remediating a particular hazardous waste site. The
report provides an introduction to the SITE Program and
the metal-enhanced dechlorination process and discusses
the demonstration objectives and activities (Section 1);
evaluates the technology's effectiveness (Section 2);
analyzes key factors pertaining to application of this
technology (Section 3); analyzes the costs of using the
technology to treat groundwater contaminated with
chlorinated VOCs (Section 4); summarizes the
technology's current status (Section 5); and presents a list
of references (Section 6). Vendor's claims and additional
performance data for the technology, and case studies of
other applications of the metal-enhanced dechlorination
technology are included in Appendices A and B,
respectively.
This executive summary briefly summarizes the
information discussed in the ITER and evaluates the
technology with respect to the nine criteria used in
Superfund feasibility studies.
Technology Description
ETI claims that the technology can treat chlorinated
methanes, ethanes, and ethenes over a wide range of
concentrations. The metal-enhanced dechlorination
technology involves oxidation of iron and reductive
dechlorination of chlorinated VOCs in aqueous media. A
reactive, zero-valent, granular iron medium oxidizes and
thereby induces dechlorination of chlorinated VOCs,
yielding simple hydrocarbons and inorganic chlorides as
by-products. The technology can be installed in-situ as a
permeable treatment wall, or can be applied aboveground
in a reactor. For in-situ applications, a reactive iron wall is
constructed by excavating a trench and backfilling it with
the reactive iron medium. The wall is oriented
perpendicular to the flow path of groundwater
contaminated with chlorinated VOCs. For some
applications, a "funnel and gate" configuration may be
used. The "funnel" consists of a scalable joint sheet pile or
slurry wall that directs water to the iron wall, or "gate,"
and also prevents untreated groundwater from flowing
around the gate. The impermeable funnels allow
containment and treatment of a contaminant plume
without constructing an iron wall across the plume's entire
width.
Overview of the Metal-Enhanced Dechlorination
Technology SITE Demonstration
The SITE demonstration of the in-situ, metal-enhanced
dechlorination process occurred between June and
December 1995. An in-situ funnel and gate system was
used to treat groundwater in a shallow, unconsolidated,
sand and gravel aquifer. The demonstration site was a
field adjacent to an inactive manufacturing facility in
central New York. Groundwater in the shallow aquifer
generally flows westward from the manufacturing facility
and across the demonstration site. Former manufacturing
operations at the facility included metal plating and
finishing. Chemicals used in the metal finishing
operations apparently resulted in groundwater
contamination; past groundwater samples collected at the
facility and at the demonstration site indicated the
presence of chlorinated VOCs in the aquifer. Chlorinated
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groundwater include trichloroethene (TCE), cis-1,2-
dichloroethene (cDCE), and vinyl chloride (VC).
For the SITE Program demonstration, a pilot-scale metal-
enhanced dechlorination system was constructed in the
field bordering the downgradient side of the facility to treat
groundwater as it moved off site. The system consisted of
a 12-foot-widc in-situ reactive iron wall (the gate) oriented
perpendicular to the groundwater flow direction. The iron
wall was about 3-feet thick, and fully penetrated the sand
and gravel aquifer. The top of the wall was above the
average seasonal high groundwater level, about 3 feet
below ground surface, and was covered with a layer of
native topsoil. The wall extended down into an underlying,
confining clay layer. The wall was flanked by 15-foot-
long sections of impermeable sheet piling. These flanking
sections created the funnel that directed flow toward the
gate and prevented untreated groundwater from bypassing
the reactive iron wall and mixing with treated water in the
demonstration study area. According to ETI, the system
captured about a 24-foot-wide portion of the contaminant
plume.
The primary objectives of the SITE demonstration were as
follows:
Determine whether treated groundwater from the
in-situ, permeable treatment wall meets NYSDEC
groundwater standards and federal MCL effluent
standards for the critical contaminants:
tetrachloroethene (PCE), TCE, 1,1,1-
trichloroethane (TCA), cDCE, trans-1,2-
dichloroethene (tDCE), and VC
Determine the removal efficiency (RE) of critical
contaminants from groundwater
The secondary objectives of the demonstration were:
Determine concentration gradients of critical con-
taminants as groundwater passes through the in-
situ treatment wall
Examine total metals, chloride, sulfate, nitrate,
bicarbonate, and non-critical VOC concentrations
in groundwater as it passes through the treatment
wall
Document geochemical conditions (specific con-
ductance, oxidation/reduction potential (Eh), pH,
dissolved oxygen, (DO), and temperature) in
groundwater passing through the treatment wall
Examine biological microorganism growth in the
reactive iron medium and in upgradient and
downgradient groundwater
Document operating and design parameters (ini-
tial weight, volume, and density of the reactive
iron medium, groundwater flow velocity) of the
in-situ,.permeable treatment wall
During the demonstration, groundwater samples were
collected from monitoring wells upgradient from, in, and
downgradient from the reactive iron wall. Groundwater
samples were collected and, analyzed for the six critical
VOCs during June, July, August, October, November, and
December 1995. 'Samples were also collected and
analyzed for noncritical parameters to support secondary
objectives. Field measurements of groundwater
elevations, dissolved oxygen (DO), temperature, specific
conductance, pH, and oxidation-reduction potential (Eh)
were also performed.
Samples indicated that influent groundwater contained
TCE at concentrations ranging from about 32 to 330
micrograms per liter (fig/L); cDCE at concentrations
ranging from, about 98 to 550 ng/L; and VC at
concentrations ranging from about 5 to 79 Ug/L. Lower
concentrations (less than 15 ug/L of TCA and 1,1-
dichloroethane (DCA) were also typically present.
Based on .SITE Program data and postdemonstration data
obtained by ETI, the average groundwater flow velocity
through the iron was probably in the range of about 0.4 to
1 foot per day. Assuming the high (conservative) velocity,
the treatment system design allowed for a minimum
contact time between groundwater and the reactive iron
medium of about 3 days. Based on the range of possible
groundwater flow velocities,, between 29,000 and 73,000
gallons of groundwater was treated between the time the
system was constructed (May 1995) and the SITE
demonstration was completed (December 1995).
SITE Demonstration Results
The following items summarize the significant results of
the SITE demonstration:
Average critical contaminant concentrations for the
downgradient wells were all below the target.
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Average critical contaminant concentrations for the
downgradient wells were all below the target
MCLs and NYSDEC standards. Individual
downgradient concentrations of critical VOCs
were predominantly nondetect. Individual results
for cDCE sporadically exceeded the NYSDEC
criterion of 5 |ig/L; however, concentrations were
significantly reduced from influent concentrations.
Minimum overall average REs were high for all
critical parameters present at significant concen-
trations in the influent groundwater. RE was
greater than 99.0 percent for TCE, 98.6 percent
for cDCE, and greater than 96.0 percent for VC.
Actual removal efficiencies may have been higher,
but are unknown, because the REs were calculated
using the detection limit of 1 ug/L to represent
effluent values that were below detectable limits.
Although significant concentrations of multi-chlo-
rinated ethenes (such as TCE) were reduced by
the technology, there was no detectable increase
in dechlorination byproducts such as cDCE, tDCE,
or VC. Concentrations of all of these compounds
in the downgradient wells were lower than in
upgradient wells, and were nondetectable in most
cases. These observations indicate that the reac-
tive iron wall dechlorinated the original com-
pounds and the byproducts.
The concentrations of metals such as calcium and
magnesium generally decreased as groundwater
moved through the iron wall, coinciding with an
increase in pH, suggesting precipitation of metal
compounds.
Bicarbonate alkalinity decreased as groundwater
flowed through the wall. This observation, com-
bined with the metals behavior and the changes in
geochemical parameters, also suggests that inor-
ganic compounds were precipitating in the reac-
tive iron.
Total PLEA analyses indicated that total microbial
activity in water in the reactive iron wall was not
significantly higher than in water in the natural
aquifer materials upgradient or downgradient from
the wall. This observation indicates that the pro-
cess is abiotic.
No significant operating problems were noted dur-
ing the SITE demonstration. According to ETI,
the most significant potential long-term problem
with respect to operation appears to be the loss of
porosity or iron reactivity due to precipitates.
However, although inorganic compounds appeared
to be precipitating during the SITE demonstration,
there was no noticeable decrease in system per-
formance over the 6-month demonstration.
Interpretation of piezometric data collected dur-
ing the demonstration was complicated by the ex-
tremely low horizontal gradient and close spacing
of the monitoring wells. For this reason, the ac-
tual flow velocity through the iron is unknown,
but appears to have been in the range of about 0.4
to 1 foot per day.
Economics
Using information obtained from the SITE demonstration,
ETI, and other sources, an economic analysis examined 12
cost categories for a scenario in which the metal-enhanced
dechlorination technology was applied at full scale to treat
contaminated groundwater at a Superfund site for a 20-
year period. The cost estimate assumed that the site
hydrogeology and the general types and concentrations of
chlorinated VOCs were the same as those encountered
during the New York demonstration. Based on these
assumptions, the total costs were estimated to be about
$18 per 1,000 gallons of groundwater treated for a
continuous wall, and $20 per 1,000 gallons treated for a
full-scale funnel and gate system. However, total cost and
cost per gallon for using this technology are highly site-
specific. Also, because this passive technology
simultaneously controls off-site contaminant migration
and removes contaminants, it combines beneficial features
of containment systems and treatment systems.
Superfund Feasibility Study Evaluation Criteria
for the Metal-Enhanced Dechlorination
Technology
Table ES-1 briefly discusses an evaluation of the in-situ
metal-enhanced dechlorination technology with respect to
the nine evaluation criteria used for Superfund feasibility-
studies when considering remedial alternatives at
Superfund sites (EPA 1988c).
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Table ES-1. Superfund Feasibility Study Evaluation Criteria for the Metal-Enhanced Dechlorination Technology
Criterion
Discussion
Overall Protection of Human
Health and the Environment
Compliance with Applicable
or Relevant and Appropriate
Requirements (ARAR)
Long-Term Effectiveness
and Permanence
Reduction of Toxicity,
Mobility, or Volume Through
Treatment
The technology is expected to protect human health and
the environment by treating water to significantly lower
concentrations of chlorinated VOCs.
Protection of the environment at and beyond the point of
discharge should be evaluated based on uses of the
receiving water body, concentrations of residual
contaminants and treatment by-products, and dilution
factors.
The technology's ability to comply with existing federal,
state, or local ARARs (for example, MCLs) should be
determined on a site-specific basis.
The technology was able to meet target effluent
concentrations based on federal maximum contaminant
levels (MCL) and New York State Department of
Environmental Conservation (NYSDEC) groundwater
discharge standards for average downgradient
concentrations of all critical parameters. After system
performance stabilized, only four cDCE results out of 90
individual critical parameter analyses slightly exceeded
NYSDEC levels.
Human health risk can be reduced to acceptable levels
by treating groundwater to site-specific cleanup levels;
the time needed to achieve cleanup goals depends
primarily on contaminant characteristics and groundwater
flow velocity.
The long-term effectiveness of the technology may
depend on periodically replacing or treating the iron
medium.
The treatment is permanent because the technology
dechlorinates chlorinated VOCs to less chlorinated
compounds.
Periodic review of treatment system performance is
needed because application of this technology to
contaminated groundwater at hazardous waste sites is
relatively recent.
Target compounds are dechlorinated to less toxic
substances by the technology; also, the concentrations of
individual target compounds and the total concentrations
of chlorinated VOCs are reduced.
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Table ES-1. Superfund Feasibility Study Evaluation Criteria for the Metal-Enhanced Dechlorination Technology (continued)
Criterion
Discussion
Short-Term Effectiveness
Implementability
Cost
Community Acceptance
State Acceptance
The technology appears to be able to reduce
chlorinated VOC concentrations as groundwater
passes through the system. However, the speed
of treatment is somewhat limited by the natural
groundwater flow velocity.
Appropriate hydrogeologic conditions should be
present and well-defined to implement this
technology! Currently, the technology is most
easily implemented at shallow depths, and is best
suited for aquifers having an underlying aquitard at
less than 50 feet below ground surface.
The site must be accessible to typical construction
equipment and delivery vehicles.
The actual space requirements will depend on (1)
the length of iron wall required to capture a
contaminant plume, and (2) the thickness required
to allow sufficient residence time for
dechlorination.
Site-specific requirements may dictate the need for
additional services and supplies.
For a full-scale, 300-foot-long continuous iron wall
operating for 20 years to treat a plume under the
same general conditions observed at the New
York site, fixed costs are estimated to be
$466,600. Annual operating and maintenance
costs, including those for residual waste handling,
analytical services, labor, and equipment
maintenance, are estimated to be about $20,900.
This criterion is generally addressed in the record
of decision after community responses are
received during the public comment period.
However, because communities are not expected
to be exposed to harmful levels of VOCs, noise, or
fugitive emissions, community acceptance of the
technology is expected to be relatively high.
This criterion is generally addressed in the record
of decision; state acceptance of the technology will
likely depend on the long-term effectiveness of the
technology.
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Section 1
Introduction
This section describes the Superfund Innovative
Technology Evaluation (SITE) Program and the
Innovative Technology Evaluation Report (ITJtiR);
provides background information on the EnviroMetal
Technologies, Inc. (ETI), metal-enhanced dechlorination
technology; identifies wastes to which this technology
may be applied; and provides a list of key contacts. This
section also provides an overview of the SITE Program
demonstration of the in-situ metal-enhanced dechlorination
process.
1.1 Description of SITE Program and
Reports
This section provides information about (1) the purpose,
history, and goals of the SITE Program, and (2) the reports
used to document SITE demonstration results.
1.1.1 Purpose, History, and Goals of the
SITE Program
The primary purpose of the SITE Program is to advance
the development and demonstration, and thereby establish
the commercial availability, of innovative treatment
technologies applicable to Superfund and other hazardous
waste sites. The SITE Program was established by the
U.S. Environmental Protection Agency (EPA) Office of
Solid Waste and Emergency Response (OSWER) and
Office of Research and Development (ORD) in response
to the Superfund Amendments and Reauthorization Act of
1986 (SARA), which recognized the need for an
alternative or innovative treatment technology research
and demonstration program. The SITE Program is
administered by ORD's National Risk Management
Research Laboratory. The overall goal of the SITE
Program is to carry out a program of research, evaluation,
testing, development, and demonstration of alternative or
innovative treatment technologies that may be used in
response actions to achieve more permanent protection of
human health and welfare and the environment.
The SITE Program consists of four component programs:
(1) the Demonstration Program, (2) the Emerging
Technology Program, (3) the Monitoring and Measurement
Technologies Program, and (4) the Technology Transfer
Program. This ITER was prepared under the SITE
Demonstration Program. The objective of the
Demonstration Program is to provide reliable performance
and cost data on innovative technologies so that potential
users can assess a given technology's suitability for
specific site cleanups. To produce useful and reliable data,
demonstrations are conducted at hazardous waste sites or
under conditions that closely simulate actual waste site
conditions.
Information collected during a demonstration is used to
assess the performance of the technology, the potential
need for pretreatment and posttreatment processing of the
waste, the types of wastes and media that may be treated by
the technology, potential operating problems, and
approximate capital and operating costs. Demonstration
information can also provide insight into a technology's
long-term operating and maintenance (O&M) costs and
long-term application risks.
Each SITE demonstration evaluates a technology's
performance in treating waste at a particular site.
Successful demonstration of a technology at one site or on
a particular waste does not ensure its success at other sites
or for other wastes. Data obtained from the demonstration
may require extrapolation to estimate a range of operating
conditions over which the technology performs
satisfactorily. Also, any extrapolation of demonstration
data should be based on other information about the
technology, such as information available from case
studies.
-------
Implementation of the SITE Program is a significant,
ongoing effort involving ORD, OSWER, various EPA
regions, and private business concerns, including
technology developers and parties responsible for site
remediation. The technology selection process and the
Demonstration Program together provide objective and
carefully controlled testing of field-ready technologies.
Innovative technologies chosen for a SITE demonstration
must be pilot- or full-scale applications and must offer
some advantage over existing technologies; mobile
technologies are of particular interest.
1.1.2 Documentation of SITE
Demonstration Results
The results of each SITE demonstration are reported in an
ITER and a Technology Evaluation Report (TER).
Information presented in the ITER is intended tp assist
Superfund decision makers evaluating specific technologies
for a particular cleanup situation. The in-situ metal-
enhanced dechlorination technology has been evaluated
against the nine criteria used for feasibility studies
supporting the Superfund remedial process. The nine
criteria are listed in Table 1-1 along with the sections of the
.ITER where information related to each criterion is
discussed. The ITER represents a critical step in the
development and commercialization of a treatment
technology. The report discusses the effectiveness and
applicability of the technology and analyzes costs
associated with its application. The technology's
effectiveness is evaluated based on data collected during
the SITE demonstration and from other case studies. The
applicability of the technology is discussed in terms of
waste and site characteristics which could affect
technology performance, material handling requirements,
technology limitations, and other factors for any
application of the technology.
The purpose of the TER is to consolidate all information
and records acquired during the demonstration. It contains
both a narrative portion and tables and graphs
summarizing data. The narrative portion includes
discussions of predemoristration, demonstration, and
postdemonstration activities as well as any deviations
from the demonstration quality assurance project plan
(QAPP) during these activities and their impact. The data
tables and graphs summarize demonstration results
relative to project objectives. The tables also summarize
quality assurance and quality control (QA/QC) data and
data quality objectives. The TER is not formally published
by EPA. Instead, a copy is retained as a reference by the
EPA project manager for responding to public inquiries
and for recordkeeping purposes. :
Table 1-1. Correlation Between Superfund Feasibility Evaluation Criteria and ITER Sections
Evaluation Criterion3
ITER Section
Overall protection of human health and the
environment
Compliance with ARARs
Long-term effectiveness and permanence
Reduction of toxicity, mobility, or volume through
treatment
Short-term effectiveness
Implementability
Cost '',..'.'
State acceptance
Community acceptance
2.1.1,2.2.2,3.5,3.6
2.1.1; 3.5; 3.6
2.1.1; 2.1.2; 2.1,4; 2.2; 3.1
2.2.1; 2.2.2; 2.2.3
2.2.1; 2.2.2; 2.2
1,6; 3.0; 5.0
4.0
2.1.1; 3.5; 3.6
2:1.1'; 3.5;-3:6
Note: a Source: EPA 1988c
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1.2 Background of the Metal-
Enhanced Dechlorination
Technology in the SITE Program
In 1993, the owner of the New York demonstration site and
its consultant, Steams & Wheler, L.L.C. (S&W),
responded to a solicitation from the SITE Program by
submitting a proposal for the SITE Program to evaluate the
metal-enhanced dechlorination process at the New York
site. Through negotiations with the New York State
Department of Environmental Conservation (NYSDEC)
and ETI, the site owners and S&W proposed constructing
a pilot-scale, in-situ treatment system employing the
metal-enhanced dechlorination process. The pilot-scale
system would be used to evaluate the technology's
suitability to remediate a chlorinated VOC plume in
groundwater at the site. SITE Program personnel
participated in the evaluation of the technology by
collecting independent data to evaluate system
performance.
1.3 Technology Description
This section describes the principles of metal-enhanced
dechlorination, the treatment system used for the
technology, and advantages and innovative features of the
technology.
1.3.1 Process Chemistry
The metal-enhanced dechlorination technology employs
an electrochemical process involving oxidation of iron and
reductive dechlorination of VOCs in aqueous media.
Although aluminum, copper, brass, standard steel, and
zinc have also been shown to promote reductive
dechlorination of VOCs, zero-valent kon has been chosen
for use in large-scale applications of the technology. Iron
is readily available, relatively inexpensive, and induces
rapid dechlorination of organic compounds (O'Hannesin
and Gillham 1992).
The technology induces conditions that cause substitution
of chlorine atoms by hydrogen.
Because chlorinated aliphatic VOCs are in a relatively
oxidized state, their reduction in the presence of reduced
metals is thermodynamically favorable. The corrosion of
zero-valent iron (Feฐ) in contact with groundwater creates
a highly reducing environment in solution, evidenced by a
decline in oxidation/reduction potential (Eh). During the
process the solution pH increases, the concentration of
OH" increases, and electrons are transferred from the metal
to the chlorinated organic compound. Overall, the
reactions cause hydrogen ions to replace the chlorine
atom(s) of the chlorinated organic compound (Gillham
1996; Focht, Vogan and O'Hannesin 1996).
The reaction mechanism is not completely understood;
several mechanisms have been proposed. According to
Gillham and O' Hannesin (1994) the following equations
may describe the reactions that take place in the presence
of water, zero-valent iron (Feฐ), and a chlorinated
hydrocarbon (RC1):
d-la)
(1-lb)
(1-lc)
(1-ld)
2Feฐ
3H2O -* 3H+ + 3OH-
2H++2e-->H2(g)
RC1 + H+ + 2e- -* RH + Cl"
In this series of equations, the conversion of Feฐ to
ferrous kon (Fe2*), commonly known as corrosion, is
described by Equation 1-la. Equation 1-lb describes the
ionization of water. The electrons released by the
corrosion of iron (Equation 1-la) react with hydrogen ions
(H+) and R-C1 according to Equations 1-lc and 1-ld,
resulting in the formation of Fe2*, hydroxyl ions (OHO,
hydrogen gas [H^g)], nonchlorinated hydrocarbons (RH),
and chloride ions (Cl~). While the ionization of water
(equation 1-lb) accompanies the dechlorination process, it
is unknown if this reaction is required for the overall
dechlorination reaction to occur (Gillham and O'Hannesin
1994; Gilham 1996).
For multi-chlorinated VOCs such as tetrachloroethene
(PCE), trichloroethene (TCE), or 1 ,2-dichloroethene (1,2-
DCE), the progression of the dechlorination reaction is not
completely understood. Chen (1995) proposed that the
dechlorination of a multi-chlorinated VOC (in this case
PCE) may follow a sequential mechanism, evidenced by
the appearance of intermediate by-products such as TCE,
1,2-DCE, and vinyl chloride (VC), as shown in the
following equations:
Feฐ -* Fe2+ + 2e-
Hp - H+ + OH'
C12C=CC12 + H+ + 2e- - C1CH=CC12 + Cl"
C1CH=CC12 + H+ + 2e- - C1CH=CHC1 + Cl'
C1CH=CHC1 + H+ + 2e- - CH2=CHC1 + Cl'
CH2=CHC1 + H+ + 2e- - CH2=CH2 + Cl'
(l-2b)
-------
Others have proposed alternate reaction mechanisms.
According to EH, recent research has indicated that the
dechlorination of PCE and TCE may involve multiple
mechanisms. Focht, Vogan, and O'Hannesin (1996)
report that for bench-scale studies involving dechlorination
of TCE, only about 10 to 20 percent of the original mass of
TCE typically appears as 1,2-DCE, and less than 1 percent
appears as vinyl chloride (VC). Based on similar mass
balance estimates, some researchers have suggested that
the predominant dechlorination reaction mechanism may
not be sequential, and may be due to a precipitous transfer
of electrons from the iron to the organic contaminant
molecule through direct contact (Gillham and O'Hannesin
1994; Gillham 1996). However, 1,2-DCE and VC are also
dechlorinated by reactive iron, and it is possible that these
compounds are generated and destroyed too rapidly to
allow detection of the full amounts generated.
For long-term remediation projects using this technology,
decision makers and technology designers should be
aware of the possibility of formation of by-products, such
as 1,2-DCE and VC if multi-chlorinated compounds such
as TCE or PCE are incompletely dechlorinated. However,
this effect was not observed during the New York
demonstration. The results of the New York
demonstration indicated that significant decreases in TCE,
cDCE, and VC occurred as groundwater moved
throughout the reactive iron. No measurable increase in
the amounts of expected dechlorination by-products
(cDCE and VC) was observed; effluent concentrations of
cDCE and VC were significantly less than influent levels
during all months of testing (see Section 2.1.1).
Past research by ETI and others has also suggested that
when the process is used to dechlorinate VOCs in
groundwater that also contains soluble metal species, the
dechlorination reaction is accompanied by precipitation of
metal compounds from the groundwater. If no oxygen is
present and pH becomes sufficiently high, ferrous
hydroxide [Fe(OH)2] may precipitate:
+ + 20H--Fe(OH),(s)
(1-3)
Carbonate (CO320 may react with Fe2* to form ferrous
carbonate (FeCO3), known as siderite:
CO32--FeCO3(s)
(1-4)
Because iron-hydroxide and iron-carbonate precipitates
are formed during treatment, the concentrations of
dissolved iron in the effluent are expected to be relatively
low. Depending on concentrations of soluble metal
compounds in influent groundwater, other carbonates
such as calcium carbonate, may precipitate (Gillham
1996; Reardon 1995).
1.3.2 General Application and Design of
Metal-Enhanced Dechlorination
Process Systems
The metal-enhanced dechlorination process uses a
reactive, zero-valent, granular iron medium to perform in-
situ remediation of groundwater contaminated with
chlorinated VOCs. Chlorinated VOCs are among the most
pervasive groundwater contaminants at Superfund and
other hazardous waste sites.
The technology is typically installed as a permeable
subsurface wall; the dechlorination reaction described in
Section 1.3.1 occurs as groundwater flows through the
wall. For this reason, optimal site conditions for
application of this technology include shallow depth to
groundwater and the presence of a confining layer beneath
the contaminated aquifer. Also, installation of in-situ
systems may require excavation to the underlying
confining layer, and therefore the thickness and depth to
the bottom of the saturated zone are determining factors
for application of this technology.
The technology may be installed as a continuous, reactive
subsurface wall, or as a configuration of alternating
"funnels" and "gates". For funnel and gate configurations,
impermeable sections of scalable joint sheet piling or
slurry walls contain the contaminant plume and funnel
groundwater flow through the iron wall or gate. The
number and dimensions of the gates required depends on
the size of the contaminant plume and hydrogeologic
factors such as gradient, flow velocity, and saturated
thickness.
The metal-enhanced dechlorination process may also be
installed in an aboveground reactor, supporting
conventional pump-and-treat operations. Aboveground
reactors may be particularly suited to short-term, small-
scale remediation projects requiring treatment of
relatively small amounts of groundwater, or for sites
where excavation and construction activities in the
immediate vicinity of a contaminant plume are
impractical. For aboveground applications, groundwater
is extracted from the aquifer and pumped to the reactor for
-------
treatment. The SITE Program evaluated a pilot-scale
aboveground reactor at a site in New Jersey in 1994 and
1995. (The results of the aboveground reactor
demonstration were reported in a previous 1'i'HR (EPA
1997).
The in-situ system design used during the SITE
demonstration was a subsurface treatment cell consisting
of one reactive iron wall flanked by two impermeable
sheet piling sections, as shown in Figure 1-1. The funnel
and gate system used was not designed to capture and treat
the entire chlorinated VOC plume present in groundwater
at the site, but rather to evaluate the technology's
effectiveness at pilot scale. Pilot scale systems allow for
measurement, control, modification, and optimization of
design and operating parameters before construction of the
full scale system. The system may eventually be expanded
or replaced by a full scale system consisting of several
alternating funnel and gate sections or a continuous iron
wall to capture and treat the entire plume (ETI 1996d).
1.3.3 Advantages and Innovative
Features of the Metal-Enhanced
Dechlorination Process
Table 1-2 compares the in-situ metal-enhanced
dechlorination technology to several other treatment
options for water contaminated with chlorinated VOCs.
Common ex-situ methods for treating groundwater
contaminated with solvents and other organic compounds
include air stripping, steam stripping, carbon adsorption,
biological treatment, chemical oxidation, and photolysis.
The metal-enhanced dechlorination technology offers a
major advantage over some of these more conventional
treatment technologies because the process destroys
hazardous substances rather than transferring them to
another medium, such as activated carbon or air.
The technology can treat groundwater with relatively high
concentrations of chlorinated VOCs. For example, as
indicated by the case studies in Appendix B, the
technology has been used to treat groundwater containing
chlorinated VOCs at concentrations up to about 300,000
ug/L. The contaminant loading mass and rate, relative to
the available iron surface area in the system, affects
system performance (see Section 3.1); higher contaminant
concentrations may increase the amount of iron required to
completely dechlorinate a substance and all associated
dechlorination by-products. However, the reactive iron is
a by-product of metal machining and finishing operations,
and is therefore readily-available and relatively inexpensive
(Gillham 1995; ETI 1996d).
A significant advantage of the metal-enhanced
dechlorination process over conventional pump- and-treat
technologies is that it can treat groundwater in-situ,
eliminating the need to extract contaminated groundwater
before treatment. In-situ systems also eliminate the need
to manage treated effluent that can lead to relatively high
costs for conventional, ex-situ technologies. Also, in-situ
systems eliminate the need for intrusive surface structures,
allowing less restricted long-term use of the area where the
system is installed.
Once installed, operating requirements are minimal.
Because the technology is a passive treatment process
there are no moving parts and no utilities are required. The
system is installed below ground, and therefore is not
subject to the effects of adverse weather conditions.
Long-term (greater than 5 years) data for field applications
of in-situ systems are unavailable at the time of this report;
therefore, the useful life of the reactive iron under field
conditions is unknown. Precipitates may reduce the
porosity of the iron or block the available reactive surface
area. The results of a previous SITE Program
demonstration of the aboveground reactor indicated that a
portion of the iron would periodically require mechanical
mixing, treatment, or replacement to maintain target
removal efficiency levels (EPA 1997). However, no
decrease in the in-situ system's performance was
detectable over the 6-month New York demonstration.
1.4 Applicable Wastes
According to ETI, existing performance data indicates that
the metal-enhanced dechlorination process is applicable to
a wide range of chlorinated methanes, ethanes, and
ethenes in water (Focht, Vogan, and O'Hannesin 1996).
Research is currently underway at other sites to determine
the technology's ability to reduce concentrations of other
types of substances such as hexavalent chromium (Puls,
Powell, and Paul 1995; ETI 1996c). At the New York site,
the SITE Program demonstration primarily examined the
technology's ability to treat six critical contaminants:
PCE, TCE, cis-l,2-dichloroethene (cDCE), trans-1,2-
dichloroethene (tDCE), 1,1,1-trichloroethane (TCA); and
VC.
10
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Table 1-2. Comparison of Technologies for Treating Chlorinated VOCs in Water
Technology
Advantages
Disadvantages
Air stripping
Steam stripping
Air stripping with carbon
adsorption of vapors
Carbon adsorption
Biological treatment (ex-situ)
Biological treatment (in-situ)
Chemical oxidation (in-situ)
Metal-enhanced
dechlorination technology (in-
situ)
Effective for high
concentrations; can treat a
wide range of VOCs;
mechanically simple;
relatively inexpensive
Effective for all
concentrations and many
types of VOCs
Effective for high
concentrations and many
types of VOCs
Low air emissions; effective
for high concentrations
Low air emissions; relatively
inexpensive
Relatively inexpensive; may
not require utilities; can be
constructed without obtrusive
surface structures
No air emissions; no
secondary waste; VOCs
destroyed; can be applied
without obtrusive surface
structures
Dechlorinates chlorinated
VOCs to less hazardous
substances; generates no air
emissions and no secondary
waste; no chemicals (such as
O3 or H2O2) required; minimal
maintenance required;
operates passively; no
utilities required; in-situ
systems can be constructed
without obtrusive surface
structures
Inefficient for low
concentrations; VOCs
discharged to air or require
secondary "polishing"
VOCs discharged to air or
require secondary "polishing";
high energy consumption
Sometimes inefficient for low
concentrations; requires
disposal or regeneration of
spent carbon; relatively
expensive
Sometimes inefficient for low
concentrations; requires
disposal or regeneration of
spent carbon; relatively
expensive
Inefficient for high
concentrations; slow rates of
removal; sludge treatment
and disposal required
Slow rate of treatment
May not be cost effective for
high contaminant
concentrations; requires
chemicals such as O3 or
H202.
Inability to treat some VOCs;
potential for gradual loss of
hydraulic conductivity and
reactivity of iron; potential for
formation of by-products;
construction requires
displacement and
management of potentially
contaminated subsurface
soils; geologic conditions may
preclude its use at some sites
11
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1.5 Overview of the In-Situ, Metal-
Enhanced Dechiorination
Technology SITE Demonstration
This section provides an overview of the site,
predemonstration and postdemonstration activities, and
SITE Program demonstration objectives and procedures.
1.5.1 Site Background
The SITE Program demonstration of the in-situ metal-
enhanced dechlorination process was conducted over a 6-
month period from June through December 1995. The
demonstration took place at an inactive manufacturing
facility in central New York state. Former operations at
the facility included electroplating and metal finishing
(Steams and Wheler [S&W] 1993).
The site is located in a river valley and overlies
unconsolidated materials consisting of a clayey sand and
gravel water-bearing zone overlying a dense clay
confining layer. The top of the clay layer is about 13 to 16
feet below ground surface. The depth to groundwater
varies seasonally, but typically ranges from about 3 to 7
feet below ground surface. The predominant groundwater
flow direction on site is west (S&W 1993).
Past site operations appear to have resulted in groundwater
contamination in the sand and gravel aquifer. Groundwater
samples indicated the presence of a chlorinated VOC
plume, apparently related to the electroplating and metal
finishing operations, in the west-central part of the site,
that was migrating off site to the west. Groundwater
contaminants at the site reportedly include the chlorinated
VOCs TCE, cDCE, VC, TCA, and 1,1-dichloroethane
(DCA); and other compounds (S&W 1993).
Based on the types and concentrations of contaminants in
groundwater, the hydrogeologic conditions, and the need
to construct a remediation system that would not restrict
property use, the metal-enhanced dechlorination process
appeared suited for groundwater remediation at the New
York site. The system would be used to passively treat
groundwater flowing off site to the west, inhibiting off-site
migration of chlorinated VOCs (S&W 1994).
1.5.2 Technology Design
In 1994, ETI conducted bench-scale column tests using
contaminated groundwater from the New York site.
During these studies, ETI determined the apparent half-
lives for chlorinated VOCs present in the site groundwater
samples, and for the by-products that could potentially be
generated by dechlorinating these VOCs. The half-life
data were evaluated to determine the required residence
time in the reactive iron for complete dechlorination to
occur. The residence time estimates, along with site
hydrogeologic characteristics such as hydraulic gradient
and flow velocity, determined the required thickness for
the reactive iron wall (ETI 1994).
ETI and S&W used the results of the bench-scale studies to
custom-design a pilot-scale funnel and gate system. The
design contaminant concentrations and applicable
regulatory target levels are shown in Table 1-3. The
design was based on the estimated residence time required
to dechlorinate TCE, cDCE, VC, PCE, and TCA from the
influent design concentrations to below the applicable
regulatory standards shown on Table 1-3. This time was
estimated by ETI as about 56 hours. The system design
allowed a minimum residence time of approximately 72
hours for water in the reactive iron based on a predicted
maximum groundwater flow velocity of about 1 foot per
day through the iron. ETI estimated the groundwater flow
velocity based on an assumed horizontal gradient of 0.002,
and hydraulic conductivity and porosity values of 142 feet/
day and 0.4, respectively, for the iron (ETI 1994).
7.5.3 Technology and Monitoring
System Construction
The pilot-scale funnel and gate system was constructed in
May 1995. The system was constructed in an agricultural
field adjacent to the west side of the site. Figure 1-1 shows
the treatment system area layout; Figure 1-2 shows the
system configuration hi plan view and cross-section.
The system was constructed by driving sealable-joint
sheet piling downward from the ground surface, through
the sand and gravel, and about 1 foot into the underlying
clay layer located about 15 feet below ground surface. The
sheet piling formed a rectangular box-like area
approximately 12 feet by 6.5 feet in plan. The long
dimension of this "box" was perpendicular to the
groundwater flow direction. Fifteen-foot-wide sections of
sheet piling were also driven on each end of the box. These
flanking sections of piling extended about 1 foot down into
the clay layer, creating an impermeable barrier to
groundwater flow (the funnel) on either end of the box.
12
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Table 1-3. System Design Criteria and Applicable Effluent Standards
Contaminant
TCA
PCEb
TCE
cDCE
tDCE
VC
Design Influent NYSDEC Federal Maximum
Concentration8 Groundwater Contaminant Level
(ug/L) Standard (ug/L)
(M9/L)
96
90
529
5,650
__c
220
5
5
5
5
5
2
200
5
5
70
100
2
Source: PRC 1995
Notes:
a Determined by NYSDEC.
b Included as a design parameter and critical parameter for the demonstration;
however, PCE was not detected during the SITE demonstration.
c NYSDEC did not require specification of a design influent concentration for tDCE
as tDCE was not anticipated to be present at significant concentrations in the
influent groundwater.
13
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P8
Sheet
Pile
"Funnel"
LEGEND
PS
Treatment
Cell
P3
PS
General
Groundwater
Flow Direction
P2
PI
P4
-t-
SITE Program
Monitoring Well
SITE Program
Piezometer
r.V.V.'l Iron Wall
tฑii^1 ("Gate")
Pea Gravel
P7
0'
101
SOURCE: Modified from PR01995.
APPROXIMATE SCALE: V =
Figure 1-1. SITE demonstration area layout
-------
General
Groundwater
Flow Direction
PLAN VIEW
NOT TO SCALE
Well Screen
X SITE Program
Protective
Catlngt
Monitoring Wells:
MW-D2 MW-Fป2 MW-U2
Monitoring Well E
| Aquifer Materials |
Silt and clay topsoll i
Iron Wall
(Gate)
I Pea Gravel
7\ Clay
PROFILE VIEW
Figure 1-2. Plan and profile views of funnel and gate.
-------
Soil in the area enclosed by the box was then excavated to
the top of the clay layer. Soil from the saturated zone was
placed in lined roll-off boxes and stored pending analysis
and off-site disposal. The box was then dewatered, and
sheet piling was used to divide the box into three parallel
compartments. The middle compartment, which was 3
feet wide, was backfilled with reactive iron. The
compartments on the east (upgradient) and west
(downgradient) sides of the iron (each about 1.75 feet
wide) were backfilled with pea gravel to minimize the
effects of inconsistent flow caused by heterogeneity and
anisotropy in the aquifer materials, and to facilitate
monitoring well construction. The pea gravel zones and
the iron zone are collectively referred to as the "treatment
system" or "cell" in subsequent discussions. To
differentiate, when referred to specifically, the reactive
iron zone is referred to as the "iron wall" throughout
subsequent sections. The iron and pea gravel zones were
filled to about 3 feet below grade, to allow for a seasonal
high groundwater table.
Three groundwater monitoring wells, consisting of PVC
well screens with riser pipes attached, were constructed in
each compartment. The three monitoring wells in the
upgradient pea gravel section were identified as MW-U1,
MW-U2, and MW-U3. The wells in the iron were
identified MW-Fel, MW-Fe2, and MW-Fe3; the wells in
the downgradient pea gravel section were identified as
MW-D1, MW-D2, and MW-D3.
After the monitoring wells were in place and as the
compartments were backfilled, the sheet piling dividers
between the compartments, as well as the sheet piling
forming the long, outer walls of the box (the two sections
perpendicular to the groundwater flow direction) were
removed. This allowed groundwater to enter the treatment
cell, passing in turn through the upgradient pea gravel,
reactive iron, and downgradient pea gravel, and then exit
the cell and return to the natural aquifer materials. After
the sheet piling dividers were removed, the upper 3-foot
portion of the trench was backfilled to grade with native
topsoil.
In order to provide additional information regarding
inorganic analyte concentrations downgradient from the
treatment system, three monitoring wells (MW-D4, D5,
and D6) were installed about 5 feet downgradient from the
treatment system, as shown on Figure 1-1. Eight
piezometers (P-l through P-8) were installed upgradient
from the treatment cell to evaluate the hydraulic gradient
and groundwater flow velocity in the vicinity of the
system.
1.5.4 Treatment System Operation
Flow through the cell commenced on May 18,1995. The
in-situ system passively treated contaminated groundwater
as it flowed through the reactive iron. No additional
construction or O&M activities directly related to the
metal-enhanced dechlorination process were required.
Based on data from upgradient monitoring wells MW-U1,
U2 and U3, the influent groundwater consistently
contained TCE at concentrations ranging from 32 to 330
micrograms per liter (ug/L); cDCE at concentrations
ranging from 98 to 550 ug/L; VC at concentrations
ranging from about 5 to 79 ug/L; and low levels (2 to 12
ug/L) of TCA. Trace levels (less than 5 ug/L) of 1,1-
dichloroethane (DCA) and tDCE were also sporadically
detected in the influent groundwater (see Tables Cl
through C6 in Appendix C).
Piezometric data gathered during the SITE demonstration
were inconclusive due to the low horizontal flow gradient,
but suggested that the groundwater flow velocity through
the iron wall was in the range of about 0.4 to 1 foot per day
(see Section 2.1.7). Based on these estimates, and an
assumed average saturated thickness of 10 feet, the
cumulative volume of groundwater treated between the
time of construction (May 1995) and the time the
demonstration was completed (December 1995) was in the
range of about 29,000 to 73,000 gallons.
1.5.5 SITE Demonstration Objectives
EPA and PRC established primary and secondary
objectives for the SITE demonstration of the metal-
enhanced dechlorination process. The objectives were
based on EPA's and PRC's understanding of the metal-
enhanced dechlorination process, SITE demonstration
program goals, and input from ETI. Primary objectives
were considered to be critical for the technology
evaluation, while secondary objectives involved collecting
additional data considered useful, but not critical, to the
process evaluation. The demonstration objectives were
defined in the EPA-approved QAPP dated May 1995
(PRC 1995). (A copy of the QAPP accompanies the TER.)
16
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Primary Objectives
The following were the primary (P) objectives of the
technology demonstration:
PI- Determine whether treated groundwater from
ETFs in-situ, permeable treatment wall meets
NYSDEC groundwater standards and federal
maximum contaminant level (MCL) standards for
the critical contaminants: PCE, TCE, TCA, cDCE,
tDCE,andVC.
P2 - Determine the removal efficiency of critical
contaminants from groundwater
Primary objective PI was established to directly evaluate
the metal-enhanced dechlorination process's ability to
destroy certain chlorinated VOCs present in groundwater
at the New York site, and was to be evaluated based on
VOC concentration data from downgradient wells MW-
Dl, D2, and D3. Primary objective P-2 was established to
provide a quantitative criterion for evaluating system
performance, and to provide a basis for comparing the
technology's performance with conventional remediation
technologies. Objective P-2 was to be based primarily on
comparison of upgradient (influent) samples from wells
MW-U1, U2, and U3 to downgradient (effluent) samples
from wells MW-D1, D2, and D3.
Secondary Objectives
The following were the secondary (S) objectives of the
demonstration:
SI- Determine concentration gradients of critical
contaminants as groundwater passes through the
in-situ treatment wall
S2 - Examine total metals, chloride, sulfate, ni-
trate, bicarbonate, and noncritical VOC concen-
trations in groundwater as it passes through the
treatment wall
S3 - Document geochemical conditions in ground-
water as groundwater passes through the treatment
wall
S4 - Examine biological microorganism growth
in the reactive iron medium and in upgradient and
downgradient groundwater
S5 - Document operating and design parameters
of the in-situ, permeable treatment wall
Secondary objective S1 was to be evaluated based oh data
from all nine wells in the treatment cell. Objectives S2and
S3 were to be evaluated by comparison of data from all
nine wells in the treatment cell (and the three downgradient
wells in the aquifer for some parameters), thus providing
data on the performance of the reactor, the dechlorination
reaction mechanism, and changes in treated groundwater
chemistry. Objective S4, which would also be evaluated
based on data from the 12 monitoring wells, was
established to demonstrate that the metal-enhanced
dechlorination process is abiotic, and also to evaluate the
potential effect of bacterial growth on the reactive iron.
Objective S5 was established to provide data for
estimating costs associated with use of the in-situ metal-
enhanced dechlorination process, and was to be based on
observations during construction, demonstration data,
postdemonstration data (if feasible), and data to be
provided by S&W and ETI. (Table 2-1 in Section 2
summarizes the demonstration objectives and purposes
and the evaluation criteria for each objective, as well as key
demonstration findings with respect to each objective.)
1.5.6 Demonstration Procedures
The SITE Program evaluated the treatment system's
effectiveness over a period of about 6 months by collecting
independent data. In general, three types of data were
obtained: 1) analytical data for groundwater samples
collected from monitoring wells located in and adjacent to
the reactive iron wall; 2) construction and design data and
observations, such as bulk density of the iron and geologic
conditions; and 3) piezometric data from the 12
monitoring wells and eight piezometers. Data collection
procedures for the demonstration were specified in the
EPA-approved QAPP written specifically for the in-situ
metal-enhanced dechlorination technology demonstration
(PRC 1995). Detailed discussions of the sample collection
techniques, analytical methods, and deviations from the
QAPP are discussed in detail in the TER, which is
available from the EPA project manager (see Section 1.7).
Prior to the demonstration, SITE Program personnel
observed the construction of the treatment cell and
collected samples of the reactive iron medium. The SITE
team laboratory analyzed the iron samples to determine the
bulk density of the reactive iron medium. SITE Program
17
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personnel also oversaw the installation of eight
piezometers (P-l, P-2, P-3, P-4, P-5, P-6, P-7, and P-8)
upgradient of the reactive cell and three groundwater
monitoring wells downgradient from the cell (see Figure
1-1).
During the demonstration, SITE Program personnel
collected groundwater samples from the monitoring wells
in and downgradient from the treatment cell, as specified
by the QAPP. The first round of sampling was conducted
in June, about 2 weeks after installation of the treatment
cell and completion of monitoring well development.
Subsequent sampling events occurred in July, August,
October, November, and December 1995.
During each sampling event, sample fractions for VOC,
bicarbonate alkalinity, chloride, sulfate, nitrite nitrogen,
and total nitrate/nitrite nitrogen analysis were collected
from the nine wells in the treatment cell. SITE Program
personnel also collected groundwater sample fractions for
metals analysis from the nine wells in the cell and the three
downgradient wells located outside of the cell. Sample
fractions were collected from all 12 wells for phospholipid
fatty acid (PLFA) analysis during June, October, and
December. SITE Program personnel also prepared
and submitted QA/QC samples as specified in the EPA-
approved QAPP (PRC 1995). Samples were shipped to
off-site laboratories for analysis.
In addition to the water samples collected for laboratory
analyses, SITE Program personnel collected samples for
field measurements of dissolved oxygen (DO), temperature,
specific conductance, pH, and Eh. Also, field personnel
measured the depth to water in the monitoring wells and
piezometers to determine the elevation of the piezometric
surface and evaluate the hydraulic gradient in the vicinity
of the treatment system.
The first sampling event (June 6 through 8) was performed
after at least two pore volumes of groundwater had passed
through the reactive iron, assuming a minimum flow
velocity of about 0.4 foot per day (see Section 2.1.7). One
pore volume equals the volume of saturated pore space of
the reactive iron medium and is estimated by the developer
as about 40 to 45 percent of the total volume of the reactive
iron medium, or about 1,200 gallons in this case.
However, based on subsequent inspection of the June data,
a sufficient amount of water had not yet passed through the
system before the June sampling event to allow the
downgradient wells (MW-D1 through D-6) to accurately
represent treated groundwater conditions. For this reason,
the usefulness of the June data is limited (see Section 2.1).
1.6 Postdemonstration Activities
Interpretation of data gathered from the piezometers
during the SITE demonstration regarding groundwater
flow velocity was complicated by several factors (see
Section 2.1.7). For this reason, approximately 6 months
after the SITE demonstration was completed, personnel
from ETI and S&W performed a bromide tracer study to
provide a more accurate determination of the groundwater
flow velocity and the residence time in the reactive iron.
ETI subsequently performed another study in November
1996 using a downhole flow meter to attempt to confirm
the groundwater flow velocity. These studies were not
performed under the supervision of the SITE Program; for
this reason, the test procedures are not discussed in detail in
this ITER. However, ETI's results are discussed in Section
2.1.7.
1.7 Key Contacts
Additional information on the metal-enhanced
dechlorination process, ETI, the SITE Program, and the
New York demonstration site is available from the
following sources:
Metal-Enhanced Dechlorination Process
John L. Vogan
Project Manager
EnviroMetal Technologies, Inc.
42 Arrow Road
Guelph, Ontario, Canada NIK 1S6
(519) 824-0432
SITE Program
Dr. Chien T. Chen
Project Manager
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
2890 Woodbridge Avenue, Bldg. 10
Edison, NJ 08837-3679
(908) 906-6985
Annette M. Gatchett
Associate Director of Technology
U.S. Environmental Protection Agency
Land Pollution and Remediation Control Division
18
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National Risk Management Research Laboratory
26 West Martin Luther King Jr. Drive (MD 215)
Cincinnati, OH 45268
(513) 569-7697
New York Demonstration Site
Diane Clark
Senior Engineer
Stearns & Wheler, L.L.C.
One Remington Park Dr.
Cazenovia, NY 13035
(315) 655-8161
19
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Section 2
Technology Effectiveness Analysis
This section addresses the effectiveness of the metal-
enhanced dechlorination technology for treating
groundwater contaminated with chlorinated VOCs. This
evaluation of the technology's effectiveness is based
mainly on the demonstration results supplemented by
additional performance data from other applications of
this technology and postdemonstration data obtained by
ETI.
Vendor claims regarding the effectiveness of the metal-
enhanced dechlorination technology are presented in
Appendix A. Case studies that describe other applications
of the metal-enhanced dechlorination technology are
presented in Appendix B. Tables summarizing the
laboratory analytical data for groundwater samples
collected during the demonstration are included in
Appendix C.
2.1 SITE Demonstration Results
This section summarizes the results from the SITE
demonstration of the metal-enhanced dechlorination
technology for both critical and noncritical parameters,
and is organized according to the project objectives stated
in Section 1.5.5. Sections 2.1.1 and 2.1.2 address the
primary objectives, and Sections 2.1.3 through 2.1.7
address secondary objectives. Table 2-1 summarizes the
key demonstration results with respect to the project
objectives and summarizes the evaluation criteria for each
objective.
The analytical data for samples collected from
downgradient wells MW-D1, D2, and D3 in June (about 2
weeks after the treatment wall was constructed) were
inconsistent with data collected from the same wells in
subsequent months, and do not appear to be representative
of actual treated effluent concentrations. For example, as
shown in Table C-l in Appendix C, the average cDCE
concentration in wells MW-D1, D2, and D3 in June was
30.7 ug/L; however, as shown in Tables C-2 through C-6,
the cDCE concentration in these wells in subsequent
months ranged from about 1.6 to 7.5 ug/L. The treatment
cell was dewatered during construction; when the sheet
piling was first removed from the upgradient and
downgradient sides of the cell groundwater flowed back
into the cell from both the upgradient and downgradient
sides. The June analytical data appear to indicate that a
sufficient quantity of water had not yet passed through the
wall to completely flush residual, untreated water from the
downgradient pea gravel zone. For this reason, the June
data were not used to determine average concentrations
and are not discussed in detail for most parameters.
Critical VOCs consistently detected in the influent
groundwater during the demonstration were TCE, cDCE,
VC, and TCA. TCE was consistently detected in all of the
upgradient wells at concentrations ranging from 32 to 330
ug/L; concentrations of cDCE ranged from 98 to 550 ug/
L, and concentrations of VC ranged from 4.7 to 79 ug/L.
TCA was detected in one or more upgradient wells during
all months of testing at relatively low concentrations (3.3
to 13 ug/L). Trace concentrations of tDCE (1.2 to 2.2 ug/
L) were detected in one or more upgradient wells during all
months except December. PCE was not detected in any of
the groundwater samples.
The average concentrations of all critical parameter VOCs
(with the exception of PCE) were determined for the
influent (upgradient) and effluent (downgradient)
groundwater samples. The average values, as well as the
individual, monthly data for each parameter, were
compared to target levels to support objective PI, and were
used to calculate the system removal efficiency (RE)
values to support objective P2. More detailed information
regarding data interpretation methods is presented in the
QAPP and in the TER.
20
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Table 2-1. Demonstration Results with Respect to Objectives
Objective
Description/Purpose
Evaluation Criteria
Results
P1 Determine if the technology achieves
target levels for critical VOCs (PCE,
TCE, cDCE, tDCE, TCA, and VC)
P2 Determine removal efficiency for
critical VOCs
S1 Determine concentration gradients of
critical VOCs
S2 Evaluate changes in inorganic and
noncritical VOC concentrations as
groundwater moves through treatment
cell
S3 Document geochemical conditions as
groundwater moves through treatment
cell
S4 Examine biological microorganism
growth in the wall
S5 Document operating and design
parameters
VOC concentration data from downgradient
(effluent) wells MW-D1, D2, and D3 for the
period after system performance became
relatively stable (July through December
1995)
Comparison of VOC data (July through
December 1995) from upgradient wells MW-
U1, U2, and U3 to data from downgradient
(effluent) wells MW-D1, D2, and D3
Comparison of VOC data from upgradient
(MW-U1, U2, U3), iron (MW-Fe1, Fe2, Fe3),
and downgradient (MW-D1, D2, D3)
monitoring wells
Comparison of inorganic and noncritical VOC
data from same wells as objective S1, plus
three wells outside (downgradient) of
treatment cell (MW-D4, D5, D3) (metals only)
Comparison of field parameter results from
same wells as 82
Comparison of phospholipid fatty acid data
from same wells as S3
Groundwater flow velocity (piezometric data
from all monitoring wells plus piezometers P-
1 through P-8); construction observations;
bulk density analysis of iron
Average effluent concentrations were all below target levels; four
cDCE results out of 15 measurements slightly exceeded target
levels; in all cases effluent concentrations were significantly lower
than influent concentrations
High removal efficiency for critical VOCs present at significant
concentrations in the influent (TCE, cDCE, and VC); no apparent
decrease in removal efficiency over demonstration period
Most critical VOCs were nondetectable in the iron wells, indicating
that the iron wall was thick enough to allow sufficient residence
time fordechlorination; also, no measurable increase in typical
dechlorination by-products as groundwater passed through the
system
Bicarbonate alkalinity, calcium, and several other inorganic
parameters decreased as water moved through the system,
indicating precipitation of metal compounds; one noncritical VOC
(DCA) was detected at low concentrations in the influent, and was
not detected in the iron wells or downgradient wells
Increases in pH and decreases in Eh and conductivity were
observed during all months, suggesting conditions were
conducive to metal precipitation
Data do not indicate significant biological activity in iron
About 430 cubic feet of iron used; uncompacted bulk density
measured at 140 pounds per cubic foot; low horizontal gradient
indicated possible slower groundwater flow velocity and longer
residence time in iron than anticipated
Notes: P - Primary Objective
S- Secondary Objective
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Table 2-2. Summary of Critical VOC Concentrates at Effluent Sampling Locatioos
Concentration Detected Purina Month
to
to
VOC
TCA
PCE
TCE
cDCE
tDCE
VC
VOC
TCA
PCE
TCE
cDCE
tDCE
VC
June2
MW-D1 MW-D2
<1.0 <1.0
<1.0 <1.0
52 L3
24 28
<1.0 <1.0
1.3 2J.
October
MW-D1 MW-D2
<1.0 <1.0
<1.0 <1.0
1.2 1.5
5 Lง
<1.0 <1.0
<1.0 1.2
Overall
11 A Mean
Ju|y Au9ust Effluent
MW-D3 MW-D1 MW-D2 MW-D3 MW-D1 MW-D2 MW-D3 Value3
<1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0
<1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0
fLS <1.0 <1.0 <1.0 3.3 <1.0 <1.0 <1.3
3Q 2.2 3.7 3.9 _g_ 1.6 1.9 3.9
<1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0
1.6 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0
Concentration Detected During Month
November December Sen?
MW-D3 MW-D1 MW-D2 MW-D3 MW-D1 MW-D2 MW-D3 Values3
<1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 AIK1.0
<1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 All<1.0
<1.0 1.6 <1.0 <1.0 0.91J <1.0 <1.0 0.91J-3.3
2 4.6 4.2 2.8 2.5 5JJ ง4 1.6-7.5
<1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 All<1.0
<1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0 <1.0-1.2
Taiget Effluent
Levels
MCL<
200
5
5
70
100
2
Overall
NYSDEC5
5
5
5
5
5
2
Target Effluent
Mean Levels:
Effluent
Value3
<1.0
<1.0
<1.3
3.9
<1.0
<1.0
MCL1 NYSDEC5
200 5
5 5
5 5
70 5
100 5
2 2
Notes: All values are presented in micrograms per liter.
For monthly samples, "<" (less than) symbol indicates that a compound was not detected; corresponding value is detection limit and is value used to
calculate overall mean.
Overall mean values based on one or more "nondetects" are also reported as "<" {less than) corresponding value.
Values exceeding at least one applicable target effluent standard are shown underlined.
J = Value estimated; concentration detected is below minimum quantitation limit.
1 1,1,1-trichloroethane (TCA); tetrachloroethene (PCE); trichloroethene (TCE); cis-1,2-dichloroethene (cDCE); trans-1,2-dichloroethene (tDCE)-
and vinyl chloride (VC).
2 June data were collected before representative effluent (downgradient) conditions were attained, and are not used to determine average values.
3 Value based on data collected from wells MW-D1, D2, and D3 from July through December.
4 MCL = federal maximum contaminant level.
5 NYSDEC = New York State Department of Environmental Conservation groundwater discharge standard.
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2.1.1 Objective P1: Compliance with
Applicable Effluent Target Levels
Compliance with the target levels was evaluated by
comparing the critical parameter concentrations detected
in downgradient wells MW-D1, D2 and D3 during July,
August, October, November, and December, and the
average value for each contaminant detected in these
wells, to federal MCLs and NYSDEC groundwater
discharge standards.
The detection limit for all critical parameters in the
effluent samples was 1 ug/L, and most of the samples
collected from the downgradient wells during the
demonstration did not contain detectable concentrations
of critical contaminants, with the exception of cDCE, and,
less frequently, TGE and VC. Ten out of 15 TCE results
for the period from July to December were below
detectable limits, as were 13 put of 15 VC results for the
same period. Low concentrations of cDCE were detected
in wells MW-D1, D2, andDS during each sampling event.
All critical VOC concentrations measured in individual
wells from July through December were below MCLs.
Critical VOC concentrations were also below NYSDEC
target levels in most instances (86 out of 90
measurements). Only one contaminant, cDCE, slightly
and sporadically exceeded the NYSDEC target effluent
level of 5 |jg/L during this period (well MW-D1 during
August, well MW-D2 in October, and wells MW-D2 and
D3 in December). However, the maximum cDCE
concentration detected in any of the downgradient samples
collected from July to December was relatively low (7.5
ug/L) and in all cases was significantly less than the
influent cDCE concentration detected during the same
month.
Overall, concentrations of all critical contaminants,
including VOCs such as cDCE, tDCE and VC, which are
potential by-products of the dechlorinatioh of TCE, were
significantly lower in downgradient wells than in
upgradient wells. For this reason, the VOC data appear to
indicate that residence time was sufficient to allow the
technology to dechlorinate any by-products generated
through the jdechlorination of TCE.
2.1.2 Objective P2: Critical Parameter
Removal Efficiency
The efficiency with which the in-situ metal-enhanced
dechlorination process removed contaminants from
groundwater was evaluated by comparing the average
upgradient and average downgradient concentrations of
the six critical parameter VOCs: TCA, TCE, PCE, cDCE,
tDCE, and VC. Removal efficiency for each compound
was evaluated for each of the five data sets collected after
system performance appeared to stabilize (July, August,
October, November, and December). Overall system
removal efficiency for each compound, based on values
averaged for each parameter for the period from July
through December, was also calculated. The average
upgradient and downgradient critical parameter
concentrations for each month, the overall average values
and the removal efficiency data are presented in Table 2-3.
In cases where effluent concentrations of a compound
were nondetectable, the detection limit value (1.0 ug/L),
rather than an assumed concentration of 0.0 ug/L, was
used to calculate the minimum removal efficiency. This
conservative practice, which was specified by the QAPP,
, was adopted to ensure that the removal efficiency would
not be overestimated, and assumes that a compound not
detected in the effluent at a detection limit of 1.0 ug/L may
have been present at a concentration between 0.0 ug/L and
1.0 ug/L. For this reason, the removal efficiency values in
Table 2-3 are the minimum possible values and may be
lower than the actual removal efficiencies achieved by the,
system. For example, as shown in Table 2-3, although VC,
was not detected in any downgradient wells in August the
minimum removal efficiency was not reported as "100
percent." Instead, the removal efficiency for VC was
based on an assumed average downgradient concentration
of 1.0 ug/L and was reported as "greater than 91.1
percent", indicating that the actual value lies in the range
between 91.1 percent and 100.0 percent.
The removal efficiency calculations are also influenced by
the magnitude of the influent concentrations relative to the-
detection limit value (1.0 ug/L) assigned as the effluent
concentration for nondetect situations. If low
concentrations of a VOC (for example tDCE or TCA),
were present in the influent, the assigned effluent value of
1.0 ug/L was greater in proportion to the influent
concentration than in cases where higher influent
concentrations were present (as for cDCE or TCE). For
this reason, situations involving low influent concentrations
typically resulted in lower calculated removal efficiency
values, even though the contaminant was reduced to
nondetectable levels in the effluent.
The results presented in Table 2-3 indicate that removal
efficiency was high for all contaminants present at
23
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Table 2-3. Summary of Critical Parameter Removal Efficiency: July-December 1995
Average
Upgradient
July
Average
Downgradient
Removal
Average
Upgradient
August
Average
Downgradient
Removal
Concentration Concentration Efficiency Concentration Concentration Efficiency
VOC
TCA
PCE
TCE
cDCE
tDCE
VC
(ug/L)1
<2.2
<1
180.0
290.0
<1.1
19.0
(gg/L)2 (%)3
<1 >54.5
<1 NC
<1 >99.4
3.3 98.9
<1 >9.0
<1 >94.7
(ug/L)1
4.9
<1
183.3
306.7
<1.4
11.3
(M9/L)2 (%)3
<1 >79.5
<1 NC
<1 .8 >99.0
3.2 99.0
<1 >28.5
<1 >91.1
October November
Average Average Average Average
Upgradient Downgradient Removal Upgradient Downgradient Removal
Concentration Concentration Efficiency Concentration Concentration Efficiency
(ua/L)1 (ug/L)2
TCA
PCE
TCE
cDCE
tDCE
VC
7.1
<1
143.3
380.0
1.8
60.3
<1 >85.9
<1 NC
<1.3 >99.0
4.8 98.7
<1 >44.4
<1.1 >98.1
4.9
<1
69.0
159.3
<1.3
14.3
<1 >79.5
<1 NC
<1.2 >98.2
3.9 97.6
<1 >23.0
<1 >93.0
December
Overall Minimum Removal Efficiency for
Demonstration Period;
VOC
TCA
PCE
TCE
cDCE
tDCE
VC
Average
Upgradient
Concentratio
n
(M9/L)1
12.3
<1
120.0
230.0
<1
21.7
Average
Downgradient
Concentration
(ug/L)2
<1
<1
<1
4.5
<1
<1
Removal
Efficiency
(%)3
>91.8
NC
>99.1
98.0
NC
>95.3
Overall Mean
Influent
Concentration
(M9/L)4
<6.3
<1.0
139.1
273.2
1.3
25.3
Overall Mean
Effluent
Concentration
(U3/L)5
<1.0
<1.0
<1.3
3.9
<1.0
<1.0
Minimum Removal
Efficiency
(%)6
>84.1
NC
>99.0
98.6
NC
>96.0
Notes:
: , ,
averaga value is less than value shown; applies to instances where one or more values used to calculate average were
"nondetect" and were assigned the detection limit concentration of 1pg/L.
> ปIndicates that removal efficiency is based on one or more "nondetect" values and is greater than value shown.
NCS removal efficiency not calculated; contaminant was not consistently detected in influent samples or effluent samples.
Monthly average of concentrations detected in upgradient wells MW-U1, U2. and U3-
Monthly average of concentrations detected in downgradient wells MW-D1, D2, and D3.
Monthly removal efficiency = 100 X [average upgradient concentration - average downgradient concentration]/ average
upgradient.
Mean of concentrations detected in upgradient wells MW-U1, U2, and U3 from July through December.
Mean of concentrations detected in downgradient wells MW-D1, D2, and D3 from July through December.
Overall minimum removal efficiency (RE) for each parameter is based on data collected from July through December and
calculated using the following formula: Minimum RE = 100 X [Mean Influent Concentration - Mean Effluent
Concentratton)/Mean Influent Concentration).
24
-------
significant concentrations in the influent (TCE, cDCE, and
VC). The minimum monthly removal efficiencies for
TCE ranged from greater than 98.2 percent to greater than
99.4 percent, and the overall minimum removal efficiency
was greater than 99.0 percent. For cDCE, monthly values
ranged from 97.6 percent to 99.0 percent, and the overall
minimum removal efficiency was 98.6 percent. Monthly
removal efficiency values for vinyl chloride ranged from
greater than 91.1 percent to greater than 98.1 percent, with
overall minimum removal efficiency greater than 96.0
percent. Monthly and overall removal efficiency values
were not calculated for PCE because no PCE was detected
in the influent or effluent samples during any month of
testing.
Figure 2-1 shows the calculated minimum monthly
removal efficiency values for the critical contaminants
present at significant concentrations in the influent (TCE,
cDCE, and VC). As indicated on Figure 2-1, there did not
appear to be any significant trends in the monthly system
removal efficiency for any of these contaminants from
July to December. Figure 2-1 reflects a slight decrease in
calculated removal efficiency for these three parameters in
November; however, the apparent decrease merely
reflects a decrease in influent concentrations. This
observation is significant because the results of the
inorganic analyses (see Section 2.1.4) suggest that metal
compounds were precipitating in the iron as groundwater
passed through the system. Precipitates did not noticeably
affect system performance with respect to removal
efficiency during the period of the SITE demonstration.
2.1.3 Objective S-1: Critical Parameter
Concentrations as a Function of
Sampling Location (Distance)
Figures 2-2 through 2-7 plot concentrations of critical
contaminants relative to distance as groundwater moved
through the system. Data from each group of wells
(upgradient, iron, and downgradient) were averaged for
each month to facilitate presentation of data in Figures 2-
2 through 2-7. The three data points on each graph
represent the upgradient pea gravel (distance x==0 feet; iron
(x=2.4 feet); and downgradient pea gravel (x=4.8 feet).
Only those critical contaminants consistently detected in
the influent samples are plotted in Figures 2-2 through 2-
7.
100
ฃ
I
96
94
92
90
\
V"
1 2 3 456
Month (July = 1)
TCE ซ> cDCE A VC
KB calculated for months after performance stabilized (July - December); no data collected in month 3 (September);
RE based on average values for upgradient (MW-U1,2 and 3) and downgradient (MW-D1,2, and 3) wells.
Figure 2-1. Critical VOC removal efficiency over time.
25
-------
200
150
50
cDCE TCE ATCA 0VC
Figure 2-2. Critical VOCs vs. distance-June.
1
Distance (Feet)
400
-------
400
^ 300 -
200 -
cDCE +TCE &TCA oVC
100 -
Distance (Feet)
Figure 2-4. Critical VOCs vs. distance-August.
400
300
200
1
100
*cDCE
TCA *VC
80
60
1
40 >
B
20
Distance (Feet)
ug/L=micrograms per liter; values are averages for: upgradient pea gravel (X=0 ft); iron (X=2.4 feet)
and downgradieat pea gravel (X=4.8 feet); non-detect values plotted as detection limit (1 ug/L).
Figure 2-5. Critical VOCs vs. distance-October.
27
-------
200
cDCE +TCE A-TCA ฉVC
Distance (Feet)
Figure 2-6. Critical VOCs vs. distance-November.
cDCE TCE ATCA 0VC
2 3
Distance (Feet)
ug/L=micrograms per liiter; values are averaged for: upgradient pea gravel (x=0 feet); iron (X=2.4
feet); and downgradient pea gravel (x=4.8 feet). Nondetect values plotted as detection limit (1 ug/L).
Figure 2-7. Critical VOCs vs. distance-December.
28
-------
Concentrations of critical parameters present at significant
concentrations in the influent (TCE, cDCE, and VC) were
significantly reduced as groundwater moved through the
wall. As shown in Figures 2-2 through 2-7, in most cases,
contaminants were reduced to nondetectable levels by the
time groundwater had traveled about halfway through the
iron wall. Some low concentrations of cDCE appeared to
persist; however, during all months cDCE was
significantly reduced relative to influent concentrations.
In several instances (for example, TCE in October), all
concentrations in the iron wells were at nondetectable
levels; however, trace concentrations appeared in the
downgradient wells. The presence of low concentrations
of TCE, cDCE, and other compounds in the downgradient
wells may have been caused by residual VOCs in the
natural aquifer materials on the downgradient side of the
cell continuing to leach minor amounts of chlorinated
VOCs into groundwater, and some of this water mixing
with treated water in the downgradient pea gravel zone.
The results of a previous demonstration of an aboveground
application of the metal-enhanced dechlorination process
indicated that chlorinated VOCs were persisting for longer
periods (greater distances) in the iron as the demonstration
progressed, possibly due in part to precipitate formation
(EPA 1997). However, for the in-situ system, the VOC
data do not appear to exhibit significant trends indicative
of changes in the iron's ability to dechlorinate the critical
contaminants. Critical VOC concentrations in monitoring
wells MW-Fel, MW-Fe2, and MW-Fe3, which were
located approximately halfway through the reactive iron
wall (in the direction of groundwater flow) did not
increase significantly during the demonstration period.
Although the results of the inorganic analyses suggest that
metal compounds were precipitating as groundwater
moved through the iron, these precipitates did not cause a
noticeable reduction in the iron's performance during the
demonstration period. Differences between the
performance of the aboveground reactor and that of the in-
situ system may have been due to differences between the
residence times for groundwater in the two systems;
differences in contaminant loading for the two systems;
variations between groundwater chemistry at the two
demonstration sites, or other factors.
Precipitate formation may have been less significant of a
factor in the demonstration of the in-situ system than in the
demonstration of the aboveground reactor because the
volume of water treated, flow rate, mass of iron used,
groundwater chemistry, length of demonstration period,
and other factors differed between the two demonstrations.
Also, based on the apparent groundwater flow velocities,
the reactive iron wall was probably thicker than necessary
to dechlorinate the concentrations of VOCs detected in the
upgradient wells, and therefore had excess treatment
capacity. This factor, and the availability of only one row
of measuring points in the reactive iron may have allowed
changes in the first few inches of iron on the upgradient
side of the wall to go undetected during the demonstration
period.
In summary, the data indicate two key findings with regard
to objective S-l: 1) because most contaminants were
reduced to nondetectable levels by the time groundwater
had traveled halfway through the reactive iron, the
thickness of the reactive iron wall appeared to be more
than adequate to allow sufficient residence time for
dechlorination to occur; and 2) the dechlorination of TCE
and cDCE was not causing increased concentrations of
potential by-products (cDCE and VC) in the downgradient
wells, indicating that the iron was dechlorinating all of
these compounds.
2.1.4 Objective S-2: Noncritical VOCs,
Metals, And Other Inorganic
Parameters
Tables Cl through C6 in Appendix C summarize all of the
laboratory analytical data collected during the
demonstration, including the results of the noncritical
VOC, metals, and other inorganic parameter analyses.
Specifically, these parameters were analyzed to evaluate
effects of the reactive iron on noncritical parameters, and
to provide additional data about the dechlorination of
VOCs, metal precipitation, and the potential for biological
growth. Due to the extensive number of analytical
parameters and sampling points pertaining to this
objective, only results for significant parameters are
presented in graphical format.
Noncritical VOCs
The samples were analyzed for a total of 64 VOCs on
EPA's Target Compound List (TCL); tentatively
identified compounds (TICs) were also reported. The only
significant noncritical VOC consistently detected in the
upgradient, influent groundwater was DCA, which was
detected at low concentrations (less than 6 ug/L) during all
months of testing. DCA was below detectable levels in the
29
-------
iron wells in all but two cases (MW-Fe3 in November and
December), and was below detectable levels in all of the
downgradient wells during these months. In all instances,
DCA concentrations in the iron wells and downgradient
wells were below the applicable NYSDEC and MCL
standards, both of which are equal to 5.0 ug/L. This
observation is consistent with ETI's past research data,
which indicated that the reactive iron is capable of
dechlorinating DCA (Focht, Vogan, and O'Hannesin
1996).
As indicated in Table C-2, during July TCE and cDCE
were detected in a sample from well MW-D4, and TCE,
cDCE, and VC were detected in a sample from well MW-
D5. VOC sample fractions were collected from these
wells solely to provide information to support the
demonstration health and safety program. The QAPP did
not specify collection of VOC sample fractions from these
wells to support primary or secondary objectives; for this
reason, the results are not critical parameters and are not
discussed in detail in this report. However, it should be
noted that both wells MW-D4 and MW-D5 are located
outside of the treatment cell, and the VOC sample
fractions were collected relatively early in the
demonstration (July). As previously discussed, possible
mixing of treated groundwater and residual, untreated
water may have resulted in the presence of VOCs in
samples from these wells.
Metals
The groundwater samples were analyzed for a total of 16
metals using inductively-coupled plasma (ICP) and
atomic absorption (AA) techniques. Data for several of
the metals detected appear to indicate trends indicative of
precipitate formation. These metals include calcium,
magnesium, barium, iron, and manganese.
Figures 2-8 and 2-9 summarize the average calcium and
magnesium concentrations in each row of wells (including
the downgradient wells screened hi the natural aquifer
materials) from June through December. Figure 2-10
summarizes the average calcium and magnesium data
collected from each row after system performance
stabilized (July through December). As shown by the
figures, influent concentrations of each of these metals
exhibited relative consistency among months. During all
months, concentrations of calcium generally decreased
between the upgradient wells and the iron wells, and then
appeared to gradually increase in the downgradient pea
gravel and aquifer wells. The decrease in calcium
concentrations coincided with a decrease in bicarbonate
alkalinity and an increase in measured pH values,
suggesting that geochemical conditions in the iron were
conducive to decreased solubility and increased
precipitation of calcium carbonate and other metal
compounds onto the iron.
Magnesium concentrations also generally decreased
between the upgradient pea gravel and reactive iron;
however, unlike calcium, magnesium concentrations
continued to decrease as groundwater moved through the
downgradient pea gravel, and then increased slightly in the
downgradient aquifer. This observation suggests that
magnesium compounds continued to precipitate as
groundwater moved downgradient from the reactive iron
zone. The slight increase observed in magnesium
concentrations downgradient from the cell may be due to
mixing of treated and untreated water downgradient of the
cell. Also, samples collected from wells MW-D4, D5 and
D6, which were screened in the natural aquifer materials,
generally appeared to contain a higher concentration of
suspended sediments than samples from wells screened in
the pea gravel or iron. These suspended fines may have
affected the analyses as the samples were not filtered
before analysis.
Iron and manganese concentrations are plotted in Figures
2-11 through 2-13. As evidenced by the figures, the
samples from wells in the reactive iron typically contained
the highest iron concentrations of the four rows monitored.
This is consistent with the nature of the proposed reaction
mechanism (see Section 1.3) which suggests that the
oxidation of iron and the hydrolysis of water will cause
iron compounds such as Fe(OH)2 and FeCO3 to form, and
then subsequently precipitate out due to the elevated pH
levels. In August, November, and December iron
concentrations in the downgradient aquifer wells were
higher than background concentrations but were still
relatively low (less than 1 mg/L). However, during June,
July, and October, iron concentrations in the downgradient
aquifer wells were below background levels. For this
reason, the iron data to not strongly indicate trends
regarding the persistence of dissolved iron as groundwater
moved downgradient in the aquifer.
Unlike iron, manganese concentrations appeared to
decrease between the upgradient pea gravel and reactive
iron zones, and then gradually increase in the
downgradient wells. The cause for the apparent behavior
30
-------
Month
UG (Gravel)
cTIron
B DG (Gravel)
DO Aquifer
June
77.00
14.77
19.07
82.77
~My
89.20
14.60
17.97
29.2
August
88.30
10.14
17.53
26.57
October
92.17
8.83
17.10
41.20
November
89.10
8.32
14.67
34.30
December
91.27
10.76
"17.67
35.30
mg/L = milligrams per liter; UG = upgradient; DG = downgradient
Figure 2-8. Summary of calcium data over time.
Month
i UG (Gravel)
olron
a DG (Gravel)
DG Aquifer
June
12.03
5.68
2.88
18.36
Julv
12.47
10.77
5.37
4.20
August
12.43
10.23
5.38
4.61
October
12.30
9.73
4.92
6.21
November
11.93
8.91
4.25
5.62
December
"' 12.83
8.67
5.46
6.46
mg/L = milligrams per liter; UG=upgradient; DG=downgradient
Figure 2-9. Summary of magnesium data over time.
45678
Distance (feetj
9 10 11 12
Calcium -ป. Magnesium
mg/L = milligrams per liter; values based on July-December, averaged for: upgradient (X=0 ft),
iron (x=2.4 ft); downgradient (x= 4.8 ft), and downgradient aquifer (x= 10.7 ft) wells.
Figure 2-10. Average calcium and magnesium values vs. distance.
31
-------
0.01
Month
UG (Gravel)
a Iron
B DO (Gravel)
DG Aquifer
June
4.42
16.62
1.12
4.59
July
0.10
0.43
0.05
0.09
August
0.12
0.63
0.07
0.75
October
0.10
0.30
0.10
0.02
November
0.10
O.ZB
0.12
0.60
December
0.10
0.33
0.13
0.59
mg/L milligrams per liter; UG upgradient; DG = downgradient;
all nondetect values plotted as detection limit (0.10 mg/L)
Figure 2-11. Summary of iron data over time,
1
Month
I UG Gravel
a Iron
DG Gravel
DG Aquifer
June
0.35
0.33
0.18
0.91
I JW I
0.42
0.22
0.20
0.33
August
0.43
0.17
0.23
0.38
October
0.46
0.07
0.22
0.05
November
0.36
0.05
0.13
0.44
December
0.39
cms
0.20
0.29
mg/L ป milligrams per liter; UG = upgradient; DG = downgradient;
Figure 2-12. Summary of manganese data over time.
e Iron ป Manganese
0123456789 10 11 12
Distance (feet)
mg/L = milligrams per liter; values based on July-December, averaged for: upgradient (X=0 ft);
iron (X=2.4 ft); downgradient (X=4.8 ft); and downgradient aquifer (X=10.7 ft) wells.
Figure 2-13. Average iron and manganese values vs. distance.
32
-------
is unknown. According to ETI, this may have been caused
by naturally occurring manganese in site groundwater
being absorbed into carbonate precipitates forming as
groundwater moved through the reactive iron, or other
factors (Vogan 1996). Manganese concentrations
downgradient of the wall generally appeared to be similar
to upgradient concentrations. Overall, it does not appear
that the iron wall was introducing more manganese to
groundwater than was present at naturally occurring
background levels.
As shown in Figure 2-14, barium concentrations generally
increased between the upgradient pea gravel wells and the
iron wells, and then declined. However, the magnitude of
the increase in barium lessened with each month. The
possible cause of this observation is unknown, but may be
a residual effect of the cell construction activities that
lessened with time as groundwater continued to "flush"
the reactive iron. According to ETI, after initial
emplacement the iron may have temporarily leached small
amounts of barium into groundwater passing through the
wall (ETI 1997). However, barium did not appear to be
persisting into the downgradient aquifer; barium levels
generally decreased between the reactive iron wells and
the downgradient wells.
Other Inorganic Parameters
Other inorganic parameters (bicarbonate alkalinity,
sulfate, chloride, nitrate, and nitrite were measured in the
upgradient pea gravel, iron, and downgradient pea gravel
wells.
Figures 2-15 and 2-16 plot the average bicarbonate
alkalinity concentrations in the various rows of wells. The
results indicate that bicarbonate alkalinity decreased as
groundwater moved through the reactive iron wall,
coinciding with an increase in pH, and then increased
slightly as groundwater moved downgradient. This
behavior is consistent with the results of the calcium,
magnesium, and pH analyses, which suggested that metal-
carbonate compounds were precipitating out. Figure 2-16
graphically exhibits the relationship between bicarbonate
concentrations and pH. According to Reardon (1995), as
pH increases, hydroxide (OH~) ions react with bicarbonate
ions (HCO3~) to form carbonate ions (CO.,)2", which then
may combine with iron, calcium, magnesium, and other
metals to form metal-carbonate precipitates. Equation 2-
1 shows the formation of calcium carbonate through this
mechanism:
HCO3-
CaCO3(s)
(2-la)
(2-lb)
The slight increase in bicarbonate in the downgradient pea
gravel wells is consistent with the slight drop in pH and
increase in calcium concentrations observed. These
observations indicate that the tendency for metal
carbonates to precipitate was decreasing as groundwater
passed out of the treatment cell.
As shown in Figure 2-17, influent sulfate concentrations
were generally consistent over the demonstration period,
ranging from about 14 to 20 milligrams per liter (mg/L),
and generally appeared to decrease as groundwater moved
through the treatment cell during all months. The
reduction in sulfate concentrations appeared to be more
complete and was occurring more rapidly as the
demonstration progressed. For example, in July the
average sulfate concentrations in the upgradient, iron, and
downgradient wells were 16.8, 15.5, and 10.6 mg/L,
respectively. In December the average upgradient
concentration was consistent with July (16.6 mg/L);
however sulfate was nondetectable in the iron wells and in
the downgradient wells.
Sulfate concentrations were measured to evaluate, in part,
the potential for sulfate-reducing bacterial growth and
precipitation of metal sulfates. According to ETI, sulfate
reduction may indicate biological activity in the reactive
iron. However, the PLFA analyses did not indicate
significant microbial activity in the reactive iron (see
Section 2.1.6); therefore, it is unknown if the decrease in
sulfate concentrations was due to biological activity or
other causes, such as precipitation of metal-sulfate
compounds.
Figures 2-18 and 2-19 exhibit the total nitrate/nitrite
nitrogen results. Total nitrate/nitrite and nitrite analyses
were performed on the samples from the nine wells in the
treatment cell; the total nitrate content was then
determined by calculating the difference between the total
nitrate/nitrite values and the nitrite values. Total nitrate/
nitrite concentrations detected in samples from the
upgradient pea gravel wells ranged from about 0.16 to 0.47
mg/L, and gradually decreased during the demonstration.
As shown in Tables C-l through C-6, the analyses
indicated that both nitrate and nitrite were present in the
influent groundwater. The relative proportion of each of
these compounds to the total nitrate/nitrite nitrogen
33
-------
0.7
0.6
a" 0.4
m 0.2
0.1
0
Month
uia (uravei)
oiron
ut> (uravei)
a uti Aquuer
June
0.021
O.593
0.020
0.092
July
0.02
0.31
0.02
0.027
August
0.02
0.25
0.04
0.02
October
o.oz
0.07
0.03
0.07
November
0.03
0.06
0.03
0.0393
December
0.02
0.05
0.03
0.04
mg/L milligrams per liter; UG = upgradient; DG = downgradient
Figure 2-14. Summary of barium data over time.
tJ 400
mg/L = milligrams per liter; UG = upgradient; DG = downgradient
Figure 2-15. Summary of bicarbonate alkalinity data over time.
400
I
ฃ300(1
200
100
.a
pa o
Bicarbonate -* pH
10
P
8 13
6 K
5
2 3
Distance (feet)
mg/L = milligrams per liter; values based on data from July-December, averaged for:
upgradient (x=0 ft); iron (x=2.4 ft), and downgradient (x=4.8 feet) wells.
Figure 2-16. Average bicarbonate alkalinity and pH vs. distance.
34
-------
Month
B UG (Gravel)
a lion
DG (Gravel)
June
19.6
19.4
18.5
My
16.8
15.5
10.6
August
17.8
5.4
5.0
October
16.0
5.0
5.0
November
14.3
5.0
5.0
December
16.6
5.0
5.0
mg/L = milligrams per liter; UG = upgradient; DG = downgradient;
all nondetect values plotted as detection limit (5.0 mg/L)
Figure 2-17. Summary of sulfate data over time.
Month
H UG (Gravel)
Dlron
DG (Gravel)
June
0.477
0.059
0.050
July
0.366
0.050
0.050
August
0.338
0.050
0.050
October
0.256
0.050
0.050
November
0.163
0.050
0.050
December
0.230
0.050
0.050
mg/L = milligrams per liter; UG = upgradient; DG = downgradient;
all nondetect values plotted as detection limit (0.050 mg/L)
Figure 2-18. Summary of total nitrate/nitrite data over time.
2345
Distance (feet)
Average values based on data from July - December, averaged for: upgradient (X=0 ft); iron (x = 2.4 ft);
and downgradient (X-4.8 ft) wells. Detection limit used to represent non-detect values for averaging data.
Figure 2-19. Average sulfate and total nitrate/nitrite values vs. distance.
35
-------
content varied considerably, but indicated that nitrate was
the predominant species. More significantly, the data
indicated that total nitrate/nitrite nitrogen was generally
not detectable in the samples from the wells screened in
the iron or the downgradient pea gravel. According to ET1,
nitrate consumption may be due to either abiotic or biotic
reduction of nitrate to nitrogen gas or ammonium (ETI
1997; PRC 1996). The PLFA analyses did not indicate
significant biological activity in the reactive iron; this
observation suggests that the decrease in nitrate and
sulfate concentrations was primarily due to abiotic
processes.
Chloride concentrations were determined because they
may correlate with dechlorination of VOCs. However,
because the background chloride concentrations were
relatively high compared to the influent VOC
concentrations, no significant trends in chloride
concentrations were noted during treatment as a result of
VOC dechlorination (see Tables Cl - C6).
2.1.5 Objective S-3; Eh, DO, pH,
Specific Conductivity, and
Temperature
Figures 2-20 and 2-21 summarize the average pH values
measured in the upgradient pea gravel, iron, downgradient
pea gravel, and downgradient aquifer sampling locations
during all months of testing. As shown on Figure 2-20,
groundwater in the wells screened in the reactive iron
typically exhibited the highest pH levels during all months
of testing. Generally, pH increased as groundwater moved
from the upgradient pea gravel and through the iron, and
then decreased as groundwater moved downgradient
Equations 1-la through 1-ld, and l-2a through l-2g
presented in Section 1.3.1 may explain the increase in pH.
In these reactions, H* is consumed so the pH rises.
The specific conductivity of groundwater decreased as
groundwater moved through the reactive iron, as shown in
Figures 2-22 and 2-23. The decrease in the specific
conductivity of groundwater is probably caused by the
removal of ions from groundwater during treatment.
Removal of ions may occur through the formation of
metal-hydroxide or metal-carbonate precipitates. The
formation of these precipitates may remove metal cations,
hydroxyl ions, and carbonate ions from the groundwater.
Generally, the groundwater temperature data did not
indicate any significant differences among groundwater
temperatures in the various zones of the cell or in the
aquifer. However, the average temperature data indicated
a general decrease in site groundwater temperature
between October and December. This effect is
demonstrated by the average temperature data from the
wells screened in the iron zone; these values are
summarized in Figure 2-24. The temperature of
groundwater in these wells declined about 4ฐ C between
October and December. Because the November and
December sampling events were performed during cold
weather, it is possible that the temperature measurements
were affected by ambient air cooling the measuring
device. However, due to the shallow depth to groundwater
on site, a slight decrease in groundwater temperature in
winter months is expected. As discussed in Section 3,
according to ETI, past studies involving TCE have shown
that temperature can influence the time required for
dechlorination to occur (ETI 1996a). However, in this
case the slight decrease in temperature did not appear to
noticeably affect system performance, and therefore
provided no additional data regarding the effects of
temperature on the dechlorination process. In general, in-
situ systems are less susceptible to potentially adverse
ambine temperature effects than aboveground systems.
The dechlorination reactions described by Equations 1-1
and 1 -2 indicate a loss of electrons from the oxidizing iron.
The groundwater Eh data, summarized in Figures 2-25 and
2-26, indicate that Eh decreased as groundwater moved
into the reactive iron, and then increased slightly as
groundwater moved downgradient, generally following an
opposite trend to the pH data. The trends exhibited by the
Eh data are consistent with the known electrochemical
mechanism of the dechlorination reaction; indicating that
electrons derived from the oxidizing iron cause reducing
conditions in the groundwater.
The observed reduction of chlorinated hydrocarbons and
the decreases in metals concentrations correlate with the
observation that reducing conditions were present. As
previously discussed, concentrations of calcium,
magnesium, and manganese were observed to decrease
coincident with the decrease observed in Eh and the
increase in pH, and then generally increase as groundwater
moved downgradient from the iron wall. However, while
trends observed in the Eh data may be indicative of metals
precipitating from groundwater moving through the iron,
changes in the iron's capacity to dechlorinate the critical
contaminants were not observed during the demonstration
period.
36
-------
10.00
5.00
Month
UG (Gravel)
olron
DG (Gravel)
H DG Aquifer
June
7.03
9.56
8.50
7.51
July
7.26
9.47
9.07
8.09
August
6.85
9.18
8.73
8.22
October
7.16
9.67
9.35
8.17
November
6.99
9.30
8.86
7.11
December
7.26
9.43
8.86
7.68
UG = upgradient; DG = downgradient
Figure 2-20. Summary of pH values vs. distance.
6.50
3 4 5 67 8
Distance (feet)
10 11 12
Values based on data collected from July - December, averaged for: upgradient (X=0 ft),
iron = (X=2.4 ft), downgradient (X=4.8 ft), and downgradient aquifer (X=10.7 ft) wells.
Figure 2-21. Average pH values vs. distance.
37
-------
Month
l UO (Gravel)
o Reactive Iron
I DG (Gravel)
g DG Aquifer
June
501
280
269
400
July
672
343
305
343
August
673
314
297
318
October
724
316
304
415
November
640
276
237
314
December
724
311
296
343
UG = upgradient; DG = downgradient
Figure 2-22. Summary of specific conductivity data over time.
800
5678
Distance (feet)
10 11
Values based on data from July - December, averaged for: upgradient (X=0 ft);
iron (X=2.4 ft); downgradient (X=4.8 ft); and downgradient aquifer (X=10.7 ft) wells).
Figure 2-23. Average specific conductivity values vs. distance.
38
-------
1 234 5 6
Month (June = 0)
Values based on data collected from June through December (no data collected in September);
values averaged for monitoring wells in reactive iron (MW-Fel, MW-Fe2, and MW-Fe3).
Figure 2-24. Average groundwater temperature in iron wells vs. time.
Month
UG (Gravel)
Q Iron
DG (Gravel)
DG Aquifer
June
223
-422
-525
18
July
246
41
-81
-85
August
203
92
-36
4
October
245
-194
^264
-165
November
30
-325
-123
-121
December
163
-405
-259
-87
mV = millivolts; UG = upgradient; DG = downgradient
Figure 2-25. Summary of Eh data over time.
I
200
I
100
0
-100
-200
1
2 3 4 5 6 7 8 9 10 11 12
Distance (feet)
Values based on data collected from July - December, averaged for: upgradient (X=0 ft);
iron (X=2.4 ft); downgradient (X=4.8 ft); and downgradient aquifer (x=10.7 ft) wells.
Figure 2-26. Average Eh values vs. distance.
39
-------
DO data are not presented in this ITER. The field meter
used for DO measurements performed erratically, and
lacked the capability of field calibration. For these
reasons, the quality of the DO data is unknown, and the DO
data are considered unusable.
2.1.6 Objective S-4: Biological
Microorganism Growth
According to EH and others, past studies of the metal-
enhanced dechlorination process suggest that the process
is abiotic, and biological activity does not account for a
significant amount of the chlorinated VOC reduction that
occurs. During the New York demonstration, the SITE
team collected groundwater samples for total PLFA
analysis to confirm that the process was predominantly
abiotic, and to evaluate the potential for excessive
microorganism growth that could interfere with hydraulic
flow through the iron. PLFA sample fractions were
collected in June, October, and December. During each
sampling event, the SITE team prepared replicate sample
fractions for each well to minimize the potential effects of
variability. The PLFA results for the replicate samples
from each well were averaged. These average results are
presented in Tables C-l through C-6. Figure 2-27
compares the average total PLFA concentrations for the
wells in each row (upgradient pea gravel, reactive iron,
downgradient pea gravel, and downgradient aquifer) from
each month of testing.
As in the case of the other parameters, the June PLFA data
are probably not representative of steady state conditions
in the treatment cell. Figure 2-27 shows that for June, the
average total PLFA concentration in wells in the treatment
cell was on the order of 104 to 10s picomoles/liter (pm/L).
In June there did not appear to be a significant difference
betweenthetotalPLFA hi the upgradient wells, iron wells,
and downgradient pea gravel wells. The total PLFA in the
downgradient aquifer wells was lower, on the order of 103
to 104 pm/L. The higher PLFA in the treatment cell and the
lack of variance among the PLFA results in the various
zones of the cell may be related to residual effects of the
cell construction activities, and not indicative of
significant long-term microorganism growth in the iron.
The October and December PLFA data appear to indicate
that the total microorganism population in each of the
three zones of the treatment cell was significantly lower
than in June. PLFA concentrations in the upgradient pea
gravel wells were on the order of 102 to 103 pm/L in
October, and lower yet (101 to 102pm/L) in December.
This observation may be partially due to the effects of
decreasing temperature discussed in Section 2.1.5. Most
significantly, PLFA concentrations in the iron wells in
October and December were not significantly higher than
in the upgradient pea gravel wells, and were lower than the
PLFA concentrations in the downgradient pea gravel and
aquifer wells. Total PLFA concentrations in the
downgradient aquifer wells in October and December
were hi the same general range observed in June, before a
significant amount of water had passed through the cell
and migrated downgradient. These observations suggest
that once a sufficient number of pore volumes of water had
passed through the system to minimize residual effects of
construction activities, the total microorganism population
hi the pea gravel and the reactive iron was lower than in the
natural aquifer materials. For this reason, the results of the
PLFA analyses correlate with past research by others
indicating that the dechlorination process is abiotic
(Gillham and O'Hannesin 1994).
As discussed in Section 2.1.7, the groundwater flow
velocity estimates were complicated by the low hydraulic
gradient. However, there was no measurable decrease in
flow velocity over the course of the demonstration. Also,
system performance appeared to remain generally
consistent throughout the demonstration. For these
reasons, biological growth did not appear to be interfering
with the flow of groundwater through the reactive iron,
further indicating that biological activity in the iron was
not significantly greater than in the natural aquifer
materials.
2.1.7 Objective S-5: Operating and
Design Parameters
Table 2-4 summarizes information collected during the
SITE demonstration regarding operating and design
parameters. The bulk density analysis of the iron indicated
an average (uncompacted) bulk density of approximately
2.25 grams per cubic centimeter, or 140 pounds per cubic
foot. About 35 to 40 tons of iron was used to construct the
cell; ETI estimates that the bulk density of the iron in the
cell was probably greater than the laboratory-measured
value due to settling. According to ETI, typical density for
iron obtained from the supplier used for the New York
Demonstration (Master Builders, Inc.) is about 160 to 180
pounds per cubic foot after settling (ETI 1996a; 1996d;
1997).
40
-------
8
I
ง
100000
10000
1000
100
10
/
/
o
-0-
June
0 October A December
j L
5 6 7
Distance (feet)
10 11 12
Notes: PLFA concentrations are averages for wells in following areas: upgradient pea gravel (X=0 ft);
reactive iron (X=2.4 ft); downgradient pea gravel (X=4.8 ft); downgradient aquifer (X=10.7 ft)
Figure 2-27. Total phospholipid fatty acids vs. distance.
41
-------
Table 2-4. Summary of Operating and Design Parameters
Reactive Iron Medium:
Initial Weight (ETI)
Volume
Density (uncompacted)
Density, after settling, estimated (ETI)
Hydraulic Conductivity (ETI)
Porosity, after settling, estimated (ETI)
Treatment Zone Dimensions:
Width (thickness) of Iron Wall
Length of Iron Wall
Height of Iron Wall
Depth of Cell
Width (thickness) of Pea Gravel Zones
Length of Sheet Piling Wings
Aquifer Saturated Thickness (average)2
Hydraulic Gradient Across Iron Wall
Width of Capture Zone (ETI)3
Groundwater Flow Velocity through Iron (range)
Volumetric Groundwater Flow Rate (range)
Cumulative Volume of Water Treated During
SITE Demonstration (range)4
About 35 to 40 tons
400ft3
140 Ib/ft3 (2.25 g/cm3)
180 Ib/ft3
142 ft/day
0.4
3 feet
12 feet
11 to 12 feet1
14 to 15 feet1
About 1.75 feet
15 feet each
10 feet
Less than 0.001 to 0.002
24 feet
0.4 to 1 ft/day (ETI)
About 15.4 to 57.6 cubic feet
(115 to 431 gallons) per day
About 29,000-73,000 gallons
Notes:
(ETI) - designates value provided by ETI
(range) - range of values provided due to uncertainty in piezometric measurements
1 Top of reactive iron wall was about 3 feet below ground surface.
2 Saturated thickness varied from about 8 to 12 feet, depending on seasonal water
table fluctuations.
3 Estimated width of portion of groundwater contaminant plume captured by the funnel
and gate system.
4 Assumes an average saturated thickness of 10 feet.
42
-------
Groundwater depth measurements collected during each
of the six sampling events were converted to piezometric
elevations relative to mean sea level (MSL) to evaluate the
horizontal gradient and groundwater flow velocity. The
piezometric elevation data are summarized in Table 2-5.
Interpretation of the piezometric data was complicated by
several factors. As evidenced by the data in Table 2-5, the
horizontal gradient measured across the study area was
extremely low, generally less than 0.001. This was
significantly less than the conservative (maximum) design
gradient value (0.002) used by ETI for the system design.
In most cases, due to the close spacing of the monitoring .
wells in the treatment cell and the accuracy limitations of
the measuring equipment (0.01 foot), differences between
water levels in wells in the treatment cell were not
accurately measurable. Also, after the in-situ system was
installed and the demonstration commenced, S&W
detected the presence of a liquid hydrocarbon layer,
related to a past release from a UST at the manufacturing
facility, on the water table upgradient from the treatment
system. This layer prevented piezometric measurements
in at least three piezometers (P-2, P-4, and P-7) in the
southern part of the demonstration area and may have
affected some measurements in other piezometers.1
Allowing for the limitations of the data, the measurements
indicated a generally westward flow direction across the
demonstration area, consistent with past data reported by
S&W (see Figure 2-28). Based on S&W's reported values
for hydraulic conductivity and porosity, of the natural
aquifer materials, the observed horizontal gradients of
0.0005 to 0.001 indicate groundwater flow velocities of
about 0.2 to 0.4 foot per day on site in the aquifer.
According to ETI, the funnel and gate configuration
typically accelerates flow velocities in the capture zone
(PRC 1997a). Assuming that thegradient in the treatment
cell was at least as high as the natural gradient on site, the
minimum estimated flow velocity through the wall was
about 0.4 foot per day. Based on the maximum measured
gradients between the wells in the cell (December), the
maximum estimated flow velocity was about 1 foot per
day. These estimates are based on ETI's reported design
values for the iron's hydraulic conductivity and porosity
(ETI 1994).
Due to the uncertainty regarding the groundwater flow
velocity, ETI performed a postdemonstration tracer study
and a flow-meter study to evaluate the flow velocity.
These studies were not part of the planned SITE
demonstration activities, and were not performed under
the direction of EPA. According to ETI, the bromide
tracer study was inconclusive; however, the flow meter
study indicated a flow velocity of about 1 foot per day in
the iron zone (ETI 1996b; 1996d).
In summary, the groundwater flow velocity through the
treatment zone appears to have been between 0.4 and 1
foot per day; however, there is uncertainty regarding the
flow velocity estimates, and it is possible that the flow
velocities were below or above this range. For this reason
the exact cumulative volume of groundwater treated
during the demonstration is unknown. Assuming the
previously-described range of flow velocities and an
average saturated thickness of about 10 feet, the volume of
groundwater treated was in the range of about 29,000 to
73,000 gallons, and residence tune in the 3-foot-thick
reactive iron wall appeared to be in the range of about 3 to
7 days. Based on the predominantly nondetectable critical
parameter concentrations in the monitoring wells screened
in the iron, VOCs appear to have been reduced below
regulatory levels within the first 1.5 feet of the reactive
iron. For this reason, the high-end (conservative) velocity
estimate of 1 foot per day indicates that contaminant
dechlorination occurred within 36 hours; the low end
estimate (0.4 feet per day) indicates that dechlorination
occurred within about 90 hours. In either case, the use of
a 3-foot-thick iron wall apparently provided adequate
residence time for this particular application during the
SITE demonstration period.
2.2 Additional Performance Data
In addition to the SITE demonstration results, several
other field applications of the in-situ metal-enhanced
dechlorination technology were reviewed to provide
additional information about the process. However, the
analytical results from these field applications have not
been subjected to EPA QA review and therefore are not
used to draw conclusions in this report. These applications
consisted of (1) the field test conducted at the Canadian
Forces Base in Borden, Ontario, Canada (Borden site); (2)
a field test and full-scale installation at a California
semiconductor facility; and (3) a full-scale installation in
Belfast, Northern Ireland. The application of the in-situ
metal-enhanced dechlorination process in each of these
sites is discussed below. Additional information
regarding case studies is presented in Appendix B.
1 S&W implemented hydrocarbon recovery operations upon discovering the
layer. Significant amounts of petroleum-related dissolved-phase contaminants
subsequently were not detected and did not affect interpretation of the
analytical data.
43
-------
Table 2-5. PfezometrJc Data
Location
P1
P2
P3
P4
PS
P6
P7
PS
MW-U1
MW-U2
MW-U3
MW-FE1
MW-FE2
MW-FE3
MW-D1
MW-D2
MW-D3
MW-D4
MW-D5
MW-D6
TOG
EL
(feet)
99.61
100.97
99.60
99.76
99.68
99.41
101.06
100.63
98.78
98.81
98.51
98.20
98.05
98.15
98.81
98.88
98.83
99.20
99.25
98.96
TOG EL
(feet
msl)
1,050.81
1,052.17
1,050.80
1,050.96
1,050.88
1,050.61
1,052.26
1,051.83
1,049.98
1,050.01
1,049.71
1,049.40
1,049.25
1,049.35
1,050.01
1,050.08
1,050.03
1,050.40
1,050.45
1,050.16
i
DTW
7.15
8.51
7.16
7.31
7.23
6.97
9.07
8.14
6.38
6.41
6.11
6.79
5.64
5.74
6.40
6.47
6.42
6.81
6.83
6.55
5/6/95
GWEL
1,043.66
1,043.66
1,043.64
1,043.65
1,043.65
1,043.64
1,043.19
1,043.69
1,043.60
1,043.60
1,043.60
1,042.61
1,043.61
1,043.61
1,043.61
1,043.61
1,043.61
1,043.59
1,043.62
1,043.61
Z
DTW
7.96
9.30
7.97
8.11
8.03
7.75
9.95
8.93
7.15
7.18
6.88
6.57
6.42
6.53
7.18
7.25
7.21
7.59
7.62
7.34
/1Q/95
GWEL
1,042.85
1,042.87
,042.83
,042.85
,042.85
,042.86
,042.31
1,042.90
1,042.83
1,042.83
1,042.83
1,042.83
1,042.83
1,042.82
1,042.83
1,042.83
1,042.82
1,042.81
1,042.83
1,042.82
j
DTW
8.18
9.51
8.17
8.33
8.24
7.98
X
9.15
7.37
7.39
7.11
6.79
6.64
6.74
7.40
7.47
7.42
7.81
7.84
7.55
3/7/95
GWEL
1,042.63
1,042.66
1,042.63
1,042.63
1,042.64
1,042.63
X
1,042.68
1,042.61
1,042.62
1,042.60
1,042.61
1,042.61
1,042.61
1,042.61
1,042.61
1,042.61
1,042.59
1,042.61
1,042.61
U
DTW
8.33
9.86
8.32
X
8.39
8.11
X
9.31
7.51
7.53
7.24
6.92
6.80
6.87
7.54
7.61
7.57
7.94
7.97
7.69
ฅ10/95
GWEL
1,042.48
1,042.31
1,042.48
X
1,042.49
1,042.50
X
1,042.52
1,042.47
1,042.48
1,042.47
1,042.48
1,042.45
1,042.48
1,042.47
1,042.47
1,042.46
1,042.46
1,042.48
1,042.47
1
DTW
7.62
X
7.61
X
7.68
7.41
X
8.61
6.81
6.82
6.56
6.22
6.08
6.19
6.85
6.91
6.87
7.24
7.28
6.99
1/7/95
GWEL
1,043.19
X
1,043.19
X
1,043.20
1,043.20
X
1,043.22
1,043.17
1,043.19
1,043.15
1,043.18
1,043.17
1,043.16
1,043.16
1,043.17
1,043.16
1,043.16
1,043.17
1,043.17
1
DTW
5.98
X
5.99
X
6.05
5.76
X
6.97
5.17
5.20
4.89
4.58
4.43
4.54
5.22
5.28
5.24
5.62
5.66
5.37
2/4/95
GWEL
1,044.83
X
1,044.81
X
1,044.83
1,044.85
X
1,044.86
1,044.81
1,044.81
1,044.82
1,044.82
1,044.82
1,044.81
1,044.79
1,044.80
1,044.79
1,044.78
1,044.79
1,044.79
Notes:
All elevation data are based on top-of-casing elevations determined by leveling on 12/4/95; all elevations relative to mean sea level (msl) datum based on data
provided by S&W.
TOG EL=eIevation of top of (inner) monitoring well casing.
DTW = depth to groundwater in monitoring well, measured from top of casing.
GW EL = elevation of piezometric surface.
X - Groundwater elevation not measured due to presence of a hydrocarbon layer.
Values in bold type indicate measurements known to be affected by the presence of a hydrocarbon layer.
-------
P8
(1044.86)
MW-D3
(1044.79)
(1044.80) MW-D2
(1044.79) MW-D6
(1044.79) MW-D5
(1 044.78) MW-D4
(1044.79) MW-D1
LEGEND
+
SITE Program
Monitoring Well
SITE Program
Piezometer
(1044.81piezometric
Elevation on
[77277] Iron Wall (Gate)
Pea Gravel
MW-Fe2
(1044.82]
MW-Fe3 (1044.81)
MW-U3 (1044.82)
MW-U2 (1044.81)
MW-U1 (1044.81)
MFe1 (1044.82)
(1044.81
P1
(1044.83)
Notes:
All elevations are relative to mean sea level (MSL) datum
and are +/- 0.01 foot accuracy.
(NM) - Piezometric elevation not measured due to presence
of hydrocarbon layer.
P6
(1044.85)
P5
(1044.83)
General
Groundwater
Flow Direction
P2
NM
P4
(NM)
pr
(NM)
SOURCE: Modified from PR01995
APPROXIMATE SCALE: 1" = 10'
Figure 2-28. Piezometric elevations-December 1995.
-------
2.2.1 BordenSite
At the Borden site, an in-situ reactive wall was installed in
June 1991 to treat groundwater contaminated with PCE
and TCE. The source of the plume was located about 13.1
feet below ground surface (bgs) and 3.3 feet below the
water table. Maximum contaminant concentrations were
about 250,000 and 43,000 ug/L for TCE and PCE,
respectively. The permeable wall was constructed about
16 feet downgradient from the source. The aquifer
material was a medium to fine sand, and the average
groundwater flow velocity was about 0.3 foot per day
(Gillham 1995; 1996).
Samples were collected and analyzed over a five-year
monitoring period. The results indicate that PCE and TCE
concentrations decreased consistently while the
concentrations of chloride increased. The average
maximum concentrations of PCE and TCE downstream of
the wall were about 10 percent of the influent
concentration, indicating a substantial reduction within
the wall. However, the concentrations of PCE and TCE hi
the treated water were about three orders of magnitude
above site drinking water standards. The results also
indicated that cis- and trans-1,2-DCE were produced as a
result of PCE and TCE degradation in the wall. DCE
isoniers were degraded as they passed through the wall,
although effluent concentrations remained above site
drinking water standards. No VC was detected in the
samples, and no bacterial growth was observed. pH
measurements were also taken, the results of which
showed little change in pH as a result of treatment
(Gillham 1995; 1996). It is suspected that the pH changes
normally seen as a result of treatment were not observed
because of the buffering capacity of the carbonate sand
used during the treatment process. EH collected core
samples of the reactive iron after two years, and again after
3.8 years, to evaluate precipitate formation. According to
ETI, examination of samples of the reactive iron using x--
ray diffraction and scanning electron microscopy
techniques showed no metal precipitates on the iron. (For
more information, see O'Hannesin 1993.)
2.2.2 California Semiconductor Facility
Groundwater from the California semiconductor facility
contained TCE at concentrations ranging from 50 to 200
ug/L, cDCE ranging from 450 to 1,000 ug/L, VC ranging
from 100 to 500 ug/L, and Freon 113 ranging from 20 to 60
ug/L. An above-ground pilot-scale demonstration reactor
containing 50 percent iron and 50 percent sand by weight
was installed at the facility and operated for a period of 9
months. Although groundwater at the site is highly
mineralized, and precipitate formation was evident, it did
not appear to interfere with treatment of the VOCs of
concern (Yamane and others 1995; Szerdy and others
1995; Focht, Vogan, and O'Hannesin 1996).
Based on the results obtained from treatment in the
reactor, a full-scale in-situ treatment wall was installed in
December 1994. The wall consisted of 100 percent
granular iron, was 3.9 feet thick, 39.4 feet long, and was
situated vertically between depths of about 13 feet and
39.4 feet bgs. A layer of pea gravel, about 1-foot thick, was
installed on both the upgradient and downgradient sides of
the iron wall (Yamane and others 1995; Szerdy and others
1995; Focht, Vogan, and O'Hannesin 1996).
Since the system was installed, no VOC concentrations
exceeding MCLs have been detected in groundwater
downgradient from the in-situ system (Yamane and others
1995; Szerdy and others 1995; Focht, Vogan, and
O'Hannesin 1996).
2.2.3 Belfast, Northern Ireland Facility
In 1995, a steel, cylindrical, in-situ reactive vessel was
installed at a depth of about 40 feet bgs at an industrial
facility in Belfast, Ireland. Groundwater at the facility
reportedly contains TCE at concentrations as high as 300
mg/L, along with lower concentrations of cDCE and vinyl
chloride (ETI 1996c).
The in-situ reactive vessel measures 4 feet in diameter
with a vertical thickness of iron measuring 16 feet. Two
100-foot-long slurry walls were installed at the facility to
divert groundwater to the reactive vessel. Groundwater
flows by gravity through the iron-laden reactive vessel and
is discharged from a piped outlet on the downgradient side
of vessel. The system was designed to allow about 5 days
of residence time. The reactive vessel is equipped with a
manhole to access the top of the iron zone in order to
scarify the iron surface if a buildup of precipitate should
occur. Total cost of the system, including the required
design efforts, the slurry walls, the reactive vessel, and the
iron was reportedly about $375,000 (ETI 1996c).
Since installing the reactive vessel, TCE concentrations in
effluent groundwater have been reduced to less than 100
Hg/L, and cDCE concentrations have been reduced to less
than 10 ug/L (ETI 1996c).
46
-------
Section 3
Technology Applications Analysis
This section discusses the following topics regarding the
applicability of the metal-enhanced dechlorination
technology: factors affecting technology performance,
site characteristics and support requirements, material
handling requirements, technology limitations, potential
regulatory., requirements, and state and community
acceptance, This section is based on the results of the New
York site! .demonstration and additional information
provided by ETI and other sources.
3.1 Factors Affecting Performance
Factors potentially affecting the performance of the metal-
enhanced dechlorination process include feed waste
characteristics, site hydrogeology and maintenance
requirements.
3.1.1 Feed Waste Characteristics
Feed waste characteristics that may affect the performance
of the metal-enhanced dechlorination technology include
the types and concentrations of organic and inorganic
substances present in the groundwater to be treated, and
geochemical parameters such as pH and possibly
temperature. .
Organic Compounds
According to ETI, the metal-enhanced dechlorination
technology has successfully degraded many halogenated
VOCs. These compounds are PCE; TCE; cDCE; tDCE,
1,1-rdichlorpethene; VC; TCA; trichloromethane; 1,2-
dibromoethane; 1,2,3-trichloropropane; 1,2-
dichloropropane; 1,1-dichloroethane and Freon 113.
Although the degradation of compounds such as
chloromethane, dichloromethane, 1,2-dichloroethane,
and 1,4-dichlorobenzene is thermodynamically favorable,
these compounds have either not been observed to degrade
in the presence of iron or have not been studied in detail
(Gillham 1996; Focht, Vogan and O'Hannesin 1996).
The performance of the metal-enhanced dechlorination
technology is typically evaluated based on the half-lives of
the compounds that it dechlorinates. The half-life is
defined as the time required to degrade a compound to one-
half of its original concentration in the medium being
treated. The half-lives of the different VOCs vary
depending on concentration and other site-specific factors.
Half-lives using treatment by the metal-enhanced
dechlorination process generally appear to be less than
those reported for biological and other natural subsurface
abiological processes (Gillham 1996).
Although the reported half-lives for a particular compound
will vary, half-lives generally tend to increase with
decreasing degrees of chlorination. This is particularly
evident when considering a single group of compounds,
such as chlorinated ethenes. PCE and TCE degrade at
reasonably similar rates; the rate is lower for DCE, and
lower yet for VC. This trend is consistent with reductive
dechlorination, since the most highly chlorinated
compounds are the most oxidized and would be expected
to be the least stable under reducing conditions (Gillham
and O'Hannesin 1994; Gillham 1996).
Although many chlorinated VOCs can be degraded in the
presence of iron, further studies are required for many of
the VOCs to evaluate the occurrence of toxic and
persistent degradation products. In addition, the
degradation products generally degrade at -much lower
rates than the parent compound (ETI 1994; Fbcht, Vogan
and O'Hannesin 1996). Therefore, even though they occur
at much lower concentrations, degradation products may
be more critical than parent compounds with regard to
determining the required residence time in the design of
metal-enhanced dechlorination technology systems.
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Inorganic Compounds
Recent research has indicated that hexavalent chromium
may be reduced by reactive iron. At a recent installation
involving a chlorinated VOC plume that also contained
hexavalent chromium, EH observed that total chromium
Was nondetectable downgradient from the system. Past
studies by others have also indicated the iron's potential to
reduce hexavalent chromium (Puls, Powell and Paul
1995). However, this potential application of the
technology has not been tested extensively.
The effect of inorganic compounds on the VOC
degradation process may representthe greatest uncertainty
with respect to the long-term, low-maintenance operation
of the in-situ metal-enhanced dechlorination technology.
At the elevated pH levels induced by the dechlorination
reaction, the Fe2* produced by the oxidation of the zero
valent iron may precipitate as Fe(OH)2, depending on the
DO concentration and provided that Eh is sufficiently low.
Iron may also precipitate as FeCO3, depending on the
carbonate concentration of the influent groundwater.
Carbonate precipitates of calcium, magnesium, barium,
and other metals may also form, particularly in the portion
of the iron along the upgradient face of the wall.
Excessive buildup of metal precipitates may limit the flow
of groundwater through the treatment system. It is also
possible that precipitates may block the iron surfaces
available for reaction causing a reduction in the iron's
reactive capacity over time, or decrease the dechlorination
reaction rate. Based on the results of the New York
demonstration, ETI estimates that formation and
deposition of metal precipitates during treatment could
cause about 4 to 7.5 percent of the original porosity in the
iron to be lost annually (ETl 1996a). However, the amount
of porosity loss is site specific; ETI reports projected
porosity losses ranging from 2 to 15 percent per year in
studies involving water from other sites. The
extrapolation of these estimates to field-scale systems
depend on the kinetics of precipitation under field
conditions (Focht, Vogan, and O'Hannesin 1996).
Site- and waste-specific treatability studies are required to
identify potential precipitates and the rates at which they
may form; possible effects on the reductive dechlorination
rate and system hydraulics; and factors that may control
precipitate formation. O&M procedures may need to
compensate for the formation of precipitates during
treatment of highly mineralized water. Before proceeding
with a full-scale remediation, it may be necessary to
develop operating methods to prevent precipitate
formation or maintenance techniques to periodically
remove precipitates once they form.
3.1.2 Hydrogeologic Characteristics
Site hydrogeology significantly affects the performance of
the in-situ metal-enhanced dechlorination technology by
controlling 1) the implementability of the technology; 2)
selection of the type of system (continuous wall or funnel
and gate); and 3) design parameters for the reactive iron
wall.
The technology's implementability is affected by the
depth to and saturated thickness of the aquifer. Many
chlorinated VOCs tend to sink when released in free phase
to an aquifer, often causing dissolved-phase contaminants
to be more concentrated in deeper portions of the aquifer.
For this reason, the technology is most effective when it
can be installed to completely intercept flow over the
entire saturated thickness of the aquifer. If possible, the
base of the iron wall should be keyed into an underlying
aquiclude to prevent untreated water from flowing beneath
the wall. As in any technology that requires trenching
activities, the technology is more easily implemented at
shallower depths (less than 50 feet). Also, if possible, the
top of the wall should be high enough to prevent seasonal
fluctuations in the water table from causing untreated
water to flow over the wall. However, extension of the
iron above the seasonal high water table may not be
practical for extremely shallow aquifers, as it is preferable
to keep the top of the iron within the saturated zone to
prevent exposure to air and excessive oxidation. ETI
currently designs systems to cover as much of the vertical
extent of the saturated zone as possible while still allowing
about 3 feet above the iron for a dense soil cover to prevent
excessive "rusting."
For these reasons, shallow unconsolidated aquifers
overlying dense clay or tight bedrock at depths less than 50
feet are more ideally suited for this technology than
bedrock aquifers or deep aquifers in general. However,
methods to facilitate deeper applications of this
technology are currently being studied and at least one
deep installation (greater than 100 feet deep) was planned
for design at the time of this report (Appleton 1996).
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3.1.3 Operating Parameters
Based on information provided by the developer, several
operating parameters that may affect system performance
were identified. These parameters include (1) iron surface
area-to-groundwater volume ratio, (2) pH, (3) residence
time, and (4) temperature of the reactor and influent water.
Ratio of Iron Surface Area to Groundwater
(Solution) Volume
A precise quantitative correlation between the iron surface
area-to-water volume ratio on the dechlorination reaction
rate has not been established. Experimental results
indicate that the rate of dechlorination increases as the
ratio of iron surface area-to-groundwater volume
increases. For this reason increasing the iron surface area
in contact with the water at any given time should increase
the dechlorination reaction rate, provided all other factors
remain constant (Gillham and O'Hannesin 1994; Gillham
1996). Based on this rationale, it appears that reductions in
the amount of iron surface area, possibly caused by
precipitates forming a coating on the reactive iron
granules, could increase contaminant half-lives.
pH
As previously discussed, the reactions which accompany
the dechlorination process cause pH to increase as water
dissociates to form H^ gas and hydrogen ions substitute for
chlorine atoms. This observation suggests that unusually
high or low influent pH in the influent groundwater may
affect the dechlorination reaction. However, the effects of
varying pH, and other geochemcial parameters (such as
DO and Eh) hi the influent groundwater were not
evaluated in detail during the SITE demonstration, as
influent groundwater pH was relatively constant
throughout the demonstration period.
Residence Time
Residence time is the time required for a "particle" of
groundwater to flow through a reactive iron treatment wall
in an in-situ installation, or through the iron layer in an
aboveground reactor. For any particular application, the
residence time of groundwater in the treatment medium
must be sufficient to reduce influent concentrations of
VOCs and potential dechlorination by-products to cleanup
standards.
To treat groundwater containing several chlorinated
VOCs having the potential to form multiple dechlorination
by-products, the total required residence time is calculated
as the sum of the estimated residence times required for
dechlorination of the compounds that have the longest
half-lives. For example, the design of the in-situ wall at
the New York site was based on maximum projected half-
lives of about 0.2 hour for TCE, 3.7 hours for cDCE, and
1.2 hours for VC. ETI estimated a required residence time
of about 55 hours for the pilot-scale system, assuming that
cDCE would require the longest residence time of any of
the compounds (37 hours), due to the greater amount of
cDCE relative to the amount of iron to be used in the
system. ETI conservatively assumed that no VC
dechlorination would occur until cDCE dechlorination
was complete. The bench-scale studies indicated that the
other compounds suspected to be present (PCE, tDCE, and
TCA) would dechlorinate simultaneously with the other
compounds, not requiring additional residence tune (ETI
1994).
In an in-situ system, residence tune is controlled by the
groundwater flow velocity and the thickness of the
reactive iron wall. The appropriate thickness is
determined by dividing the required residence time by the
groundwater flow velocity (the natural flow velocity for
continuous walls, or an accelerated velocity projected for
a proposed funnel and gate system). The wall must be
thick enough to allow adequate time for chlorinated VOCs
to be reduced from influent concentrations to the
applicable water quality criteria, and must also allow
sufficient time for dechlorination of any by-products. The
thickness of the wall should also incorporate a
contingency factor to allow for seasonal fluctuations in
flow velocity. For some applications, extra width may
also be appropriate to allow for decreases in the
performance of the upgradient portion of the iron due to
precipitate formation over time.
In an aboveground reactor, water typically flows vertically
through a reactive iron bed by gravity. The residence time
(volume of pore space in the reactive iron layer divided by
volumetric flow rate) is controlled by the hydraulic head
(which can be controlled by the influent pumping rate);
pore volume, hydraulic conductivity, and thickness of the
reactive iron layer; and the configuration of the effluent
piping. The results of a previous SITE demonstration of an
aboveground application of this technology suggested that
the same general design criteria apply as for in-situ
systems; that is, the iron layer must be sufficiently thick to
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ai low adequate residence time for dechlorination of parent
compounds and potential dechlorination by-products.
Temperature
According to ETI, laboratory testing has indicated that
temperature affects the reaction rate for the dechlorination
of TCE, and presumably would affect reaction rates for
other compounds as well (EH 1996a). Data gathered at a
previous SITE Program demonstration of an aboveground
system indicated that a gradual decline in reactor
temperature and the temperature of groundwater in the
reactor coincided with an apparent increase in the length of
time chlorinated VOCs persisted in the reactive iron bed.
However, data were insufficient to differentiate possible
temperature effects from other factors that may have
affected system performance (EPA 1997).
During the New York demonstration, data indicated a
gradual lowering of groundwater temperature in the last 2
months of the demonstration. Unlike the demonstration of
the aboveground reactor, there was no measurable
increase in the length of time required for TCE
dechlorination coincident with the temperature decline.
However, because TCE was generally below detectable
levels in the samples from the wells screened in the iron,
the length of time actually required for TCE
dechlorination to occur is unknown. For this reason, it is
possible that slight decreases in the TCE dechlorination
reaction rate occurred during the New York demonstration,
but were not detectable.
In general, in-situ remediation systems tend to be less
susceptible to temperature fluctuations than aboveground
systems. However, typical groundwater temperatures are
usually less than the ambient temperatures at which
laboratory treatability studies are performed. For
extremely shallow aquifers, groundwater temperature
may fluctuate significantly, particularly in climates that
experience extreme ranges in seasonal temperature and
precipitation. If temperature does affect the reaction rate,
colder temperatures could increase the required residence
time. For these reasons, seasonal groundwater
temperature should be considered in the system design;
design allowances (extra width) may be necessary if
preconstruction studies indicate a potential for temperature
decrease to affect the dechlorination reaction rates.
3,7.4 Maintenance Requirements
The maintenance requirements for the in-situ metal-
enhanced dechlorination system summarized in this
section are based on observations of the pilot-scale system
used during the SITE demonstration; assumptions based
on the analytical data; results of previous applications of
the technology; and discussions with ETI personnel.
Metals precipitating from groundwater may accumulate
and physically block the pore spaces on the influent side of
the reactive iron medium, reducing flow. Also, metal
precipitates may coat the reactive iron surface, reducing
the surface area available for contact with contaminated
groundwater. Precipitate formation will vary depending
on a number of site-specific factors. According to ETI,
precipitates tend to concentrate in the first few inches on
the influent side of the reactive iron. However, because
relatively few in-situ systems have been operating for
more than 2 years (at the time of this report), knowledge of
long-term trends in and effects of precipitate formation is
primarily based on extrapolations from bench scale
studies or short-term observations from recent field
applications.
Maintenance procedures to counteract the effects of
precipitate formation for in-situ systems have not been
extensively tested in the field; however, ETI is currently
studying methods of in-situ chemical or physical
treatment of the iron to remove precipitates. Possible
chemical methods considered include dissolving
precipitates by introducing mild acids upgradient from the
wall; however, this technique currently does not appear
feasible for most situations as the acid would also probably
react with the iron and cause excessive corrosion. Physical
techniques include scarifying or agitating the upgradient
side of the iron wall. ETI has suggested the use of soil
augers or mixing equipment at the interface between the
natural aquifer materials (or pea gravel, if present) and the
influent side of the iron to accomplish this task. However,
this technique has not yet been attempted at existing in-situ
installations and is untested under actual field conditions
at the time of this report. ETI estimates that some form of
maintenance to remove precipitates may typically be
required every 5 to 10 years (Focht, Vogan, and
O'Hannesin 1996).
If maintenance techniques are not successful, periodic
replacement of the iron may be necessary for long-term
(greater than 10 year) remedial programs. For some
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applications, it also may be possible to allow a sufficient
thickness contingency in the reactive iron wall to
compensate for reactivity losses caused by reductions in
the available reactive iron surface area. However, this
would not necessarily alleviate problems associated with
significant reduction of the iron's hydraulic conductivity.
Biological growth in the reactive iron did not appear to be
a significant problem during the New York in-situ
demonstration (PRC 1997). Long term performance data
for in-situ systems under a wide range of conditions are
limited; therefore, potential operating problems caused by
long-term biological growth have not been studied
extensively.
3.2 Site Characteristics and Support
Requirements
Site-specific factors can impact the application of the in-
situ metal-enhanced dechlorination process, and these
factors should be considered before selecting the
technology for remediation of a specific site. Site-specific
factors addressed in this section are site access, area, and
preparation requirements; climate; utility and supply
requirements; support systems; and personnel requirements.
According to ETI, both in-situ treatment wall installations
and aboveground treatment reactors are available (see
Section 5, Technology Status, and Appendix A, Vendor's
Claims for the Technology). The support requirements of
these systems vary. This section presents support
requirements based on the information collected for the in-
situ treatment system used at the New York demonstration
site.
3.2.1 Site Access, Area, and Preparation
Requirements
In addition to the hydrogeologic conditions that determine
the technology's applicability and design, other site
characteristics affect implementation of this technology.
The actual amount of space required for an in-situ system
depends on the required thickness and length of the
reactive iron wall, and whether a continuous wall or funnel
and gate system are used. For the New York
demonstration, the gate section comprised an area about
12feetby6.5 feet (includingthe3-foot-thick iron wall and
the adjacent pea gravel sections) in plan. In addition, the
end sections comprising the funnel extended the length of
the system by 15 feet on each end. According to ETI, the
system captured a 24-foot-wide portion of the 300-foot-
wide plume. A full-scale funnel and gate system would
typically consist of several interspersed funnels and gates
or a continuous iron wall across the entire width of the
plume. A system employing a continuous wall would
probably not be as thick as it would not employ flanking
sections of pea gravel; for example, ETI estimates that a 1 -
foot-thick wall may be adequate to treat groundwater
under the general conditions observed at the New York
site. (According to ETI, the effects of anisotropic flow are
less critical for continuous walls than for funnel and gate
systems because the continuous walls are not expected to
accelerate groundwater flow velocity.) In either case, the
length of the system will depend on the size of the
contaminant plume. Sufficient space must also be
available for monitoring wells upgradient and downgradient
from the system.
The site must be accessible to and have sufficient
operating and storage space for heavy construction
equipment. Excavating equipment is necessary to prepare
a subsurface trench. For funnel and gate systems, a crane
equipped with a pile driver is necessary to install sheet
piling and to subsequently remove the sheet piling from
the upgradient and downgradient sides of the gate. Access
for tractor trailers (for delivery of iron, construction
supplies, and equipment) is preferable. A front-end loader
may be needed to place the iron in the trench. Access for
a drill rig to install the wells for system performance
monitoring will be required, unless the wells are
constructed as integral parts of a treatment "cell."
Underground utilities crossing the path of the proposed
system may need to be relocated if present, arid overhead
space should be clear of utility lines, to allow cranes and
drill rigs to operate. The wall may need to be constructed
around existing surface structures that are on site.
Soils excavated at sites contaminated with chlorinated
VOCs may require management as a potentially hazardous
waste. For this reason, roll-off boxes to hold the soil, and
sufficient space near, but outside of the construction area
for staging the boxes should be available. In addition, a
portable tank or tanker truck should also be available for
funnel and gate installations to temporarily hold water
removed from the trench.
3.2.2 Climate Requirements
Because the in-situ metal-enhanced dechlorination
process is completely below grade and usually requires no
aboveground piping or utilities, the system does not
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appear to be significantly affected by ambient weather
conditions. For this reason, the system can be installed and
operated in virtually any climatologic zone. However,
variations in groundwater temperature may need to be
considered in the system design (see Section 3.1.3.)
3.2.3 Utility and Supply Requirements
Existing on site sources of power and water may facilitate,
but are not required, for construction activities. After the
initial construction phase, the in-situ funnel and gate
system at the New York site required no electrical power
or other utility support.
Supply requirements specific to the technology may
include fresh iron medium to replace iron that has lost an
unacceptable amount of its reactive capacity. The
frequency at which iron may need to be replaced is highly
site-specific (see Section 3.1.4). Other supplies indirectly
related to the technology include typical groundwater
sampling supplies that will be used for system monitoring.
3.2.4 Required Support Systems
No pretreatment of groundwater is necessary for in-situ
systems. As discussed in Section 1.3, potential users of
this technology must consider the possibility that the
dechlorination of some multi-chlorinated compounds
such as PCE and TCE may generate by-products such as
cDCE and VC. Properly designed systems allow
sufficientresidencetimetodechlorinate these compounds;
however, in-situ system designs may need to allow for
additional posttreatment "polishing" of system effluent in
the event that byproducts such as cDCE and VC persist. In
such cases, contingent systems such as air sparging/soil
vapor extraction (SVE) combined with carbon adsorption
of the effluent vapors may be appropriate.
S&W initially installed two PVC air sparging wells in the
downgradient pea gravel zone, as a contingency so that an
air sparging/SVE system could be rapidly constructed in
the event that persistent dechlorination by-products such
as cDCE or VC were detected downgradient from the wall.
However, the in-situ system appeared to consistently
reduce concentrations of all critical parameters and
potential by-products during the demonstration period.
For this reason, posttreatment was not implemented
during the demonstration.
3.2.5 Personnel Requirements
Personnel requirements for the system are minimal. Site
personnel must collect periodic samples to evaluate
system performance. Also, personnel should periodically
inspect the system for general operating condition.
Personnel should check water levels in the monitoring
wells and piezometers to ensure continuing flow through
the wall, and inspect the condition of the wells and
piezometers. Personnel should also inspect the condition
of the ground surface above the system and identify any
indications of potential problems, such as severe
subsidence or erosion. If possible, representative core
samples should be periodically obtained to evaluate
precipitate formation. If support systems (such as air
sparging/SVE) are used, additional on-site personnel may
be required.
Personnel requirements for long-term maintenance will
depend on the type of maintenance activities. If soil
mixing, drilling, iron replacement, or other activities
requiring specialized heavy equipment will be performed,
trained equipment operators will be required.
Personnel working with the system at a hazardous waste
site should have completed the training requirements
under the Occupational Safety and Health Act (OSHA)
outlined in 29 CFR ง1910.120, which covers hazardous
waste operations and emergency response. Personnel also
should participate in a medical monitoring program as
specified under OSHA.
3.3 Material Handling Requirements
Material handling requirements for the in-situ metal-
enhanced dechlorination technology include those for the
soil and water removed from the excavation, the reactive
iron medium, and the pea gravel or well-sand used in the
construction of the system. Groundwater removed by
trench dewatering will probably contain chlorinated
VOCs. Also, soils excavated from below the water table in
the vicinity of a chlorinated VOC plume may have become
contaminated by contact with contaminated groundwater.
For this reason, soil and water generated by construction
activities may require handling, storage, and management
as hazardous wastes. Precautions may include availability
of lined, covered, roll-off boxes, drums, or other
receptacles for the soil; solvent-resistant storage tanks for
the water; and appropriate personal protective equipment
(PPE) for handling materials containing chlorinated
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VOCs. Soils from the vadose zone should be stockpiled on
site separately from soils excavated from below the water
table, to minimize the amount of material requiring
management as potentially hazardous waste.
Precautions required for the handling of the iron and pea
gravel include those normally employed for nuisance
dusts, including the use of respiratory protection.
3.4 Technology Limitations
The in-situ metal-enhanced dechlorination technology is
limited by the ability of the reactive iron to treat
wastestreams containing only certain chlorinated VOCs,
which limits the number of sites for which the technology
may be ideally suited. Sites involving multiple types of
groundwater contaminants may not be ideally suited for
this technology.
Although recent studies by ETI and others have indicated
that other contaminants (for example, hexavalent
chromium, uranium and some other metals; some
brominated compounds; and some pesticides) may be
reduced by the technology, the reactive iron either cannot
reduce, or has not yet been extensively shown to reduce,
nonchlorinated organic compounds, some chlorinated
VOCs (such as chloromethane, dichloromethane, 1,2-
dichloroethane, and 1,4-dichlorobenzene); some metals,
and other chlorinated organic compounds such as
chlorinated phenols and most pesticides (ETI 1997; Focht,
Vogan, and O'Hannesin 1996). Aboveground systems or
other, conventional ex-situ technologies can often be
modified by adding modular, in-line pretreatment or
posttreatment components to treat multiple types of
contaminants. However, auxiliary treatment systems that
are technically adaptable to the in-situ metal-enhanced
dechlorination process appear to be limited to conventional
in-situ technologies associated with VOC removal, such
as air sparging and SVE.
The second limitation concerns the reactive iron
medium's usable life before its reactivity or hydraulic
conductivity are significantly reduced by the formation of
metal precipitates. Information regarding the useful life
of the iron is limited because no long-term (exceeding 5
years) performance data are currently available. As
discussed in Section 1.3, the driving force of the
dechlorination reaction is the corrosion of iron, or the
conversion of Feฐ to Fe2+. According to ETI, the measured
corrosion rate of iron indicates that iron will persist for
several years to decades, depending on the concentration
of VOCs in the groundwater and the flow rate through the
iron (Focht, Vogan, and O'Hannesin 1996). However,
deposition of metal precipitates on the reactive iron
medium may adversely affect system hydraulics or block
the reactive surface area of the iron particles. Although
ETI is researching maintenance techniques to counteract
these effects, the proposed techniques are unproven under
representative full-scale field conditions at the time of this
report.
During the New York demonstration, no decline in the
system's ability to dechlorinate the target compounds was
noted, although the inorganic data and geochemical
parameters suggested that metal precipitates were forming
in the iron. However, in a previous SITE Program
demonstration of an aboveground application of the
metal-enhanced dechlorination technology, "parent"
chlorinated VOCs were observed to persist longer as the
demonstration progressed. This effect was accompanied
by the appearance of low concentrations of dechlorination
by-products (cDCE and VC) in the effluent. Although
other factors may have contributed to the decline in
performance, geochemical data indicated that metal
precipitates were forming, and subsequent studies
performed by ETI confirmed that a hard precipitate layer
had formed in the upper (influent) portion of the reactive
iron bed (EPA 1997).
A third limitation of the technology is that passive systems
do not necessarily remove the contaminant source.
Although the system may be able to treat all of the
contaminated groundwater migrating from a site,
contaminant sources upgradient from the system (such as
subsurface soils) may continue to release chlorinated
VOCs to groundwater until an aggressive remediation
scheme, such as removal, is enacted. For this reason, to
achieve overall permanent remediation of a site, the
technology may be most successful if implemented in
conjunction with additional source reduction activities.
The fourth limitation pertains to the practicality of
implementing the technology at some sites. As for most
fully penetrating, in-situ containment/treatment systems,
the need for intrusive construction activities requires
significant amounts of open surface space, possibly
precluding use of this technology at some sites. Also, the
limitations of trench construction technologies tend to
make fully penetrating systems best-suited for installations
shallower than 50 feet, and often less for some soil types.
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ETI has successfully used continuous excavation/backfill
technology to install reactive iron walls, eliminating many
of the time requirements, construction costs, and safety
concerns associated with conventional trenching activities,
and future applications may test the use of deep borings
and hydraulic fracturing to install systems at greater
depths (Appleton 1996). However, ETI's deepest existing
in-situ system is about 40 feet deep. Also, the technology
may be less effective in aquifers lacking a suitable
underlying aquitard (for keying the base of the iron wall).
3.5 Potential Regulatory Requirements
This section discusses regulatory requirements pertinent
to using the in-situ metal-enhanced dechlorination process
at Superfund, Resource Conservation and Recovery
(RCRA) corrective action, and other cleanup sites. The
regulations pertaining to applications of this technology
depend on site-specific conditions; therefore, this section
presents a general overview of the types of federal
regulations that may apply under various conditions. State
and local requirements should also be considered.
Because these requirements will vary, they are not
presented in detail in this section. Table 3-1 summarizes
the environmental laws and associated regulations
discussed in this section.
During the SITE demonstration of the in-situ metal-
enhanced dechlorination process no groundwater was
pumped from the affected aquifer to above the ground
surface. Therefore, many state and federal regulations
applicable to the pumping, treatment, and disposal or
discharge of contaminated groundwater were not relevant
to this particular application, nor would they be relevant
when this technology is used in similar fashion at other
sites. If required, auxiliary posttreatment processes will
likely involve additional regulatory requirements that
would need to be addressed. This section focuses on
regulations applicable to the in-situ metal-enhanced
dechlorination technology, and briefly discusses regulations
that may apply if posttreatment is required.
3.5.1 Comprehensive Environmental
Response, Compensation, and
Liability Act
The Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA), as amended
by SARA, authorizes the federal government to respond to
releases of hazardous substances, pollutants, or
contaminants that may present an imminent and
substantial danger to public health or welfare. CERCLA
pertains to the metal-enhanced dechlorination system by
governing the selection and application of remedial
technologies at Superfund sites. Remedial alternatives
that significantly reduce the volume, toxicity, or mobility
of hazardous substances and provide long-term protection
are preferred. Selected remedies must also be cost-
effective, protective of human health and the environment,
and must comply with environmental regulations to
protect human health and the environment during and after
remediation.
CERCLA requires identification and consideration of
environmental requirements that are ARARs for site
remediation before implementation of a remedial
technology at a Superfund site. Subject to specific
conditions, EPA allows ARARs to be waived in
accordance with Section 121 of CERCLA. The conditions
under which an ARAR may be waived are (1) an activity
that does not achieve compliance with an ARAR, but is
part of a total remedial action that will achieve compliance
(such as a removal action), (2) an equivalent standard of
performance can be achieved without complying with an
ARAR, (3) compliance with an ARAR will result hi a
greater risk to health and the environment than will
noncompliance, (4) compliance with an ARAR is
technically impracticable, (5) a state ARAR that has not
been applied consistently, and (6) for fund-lead remedial
actions, compliance with the ARAR will result in
expenditures that are not justifiable in terms of protecting
public health or welfare, given the needs for funds at other
sites. The justification for a waiver must be clearly
demonstrated (EPA 1988a). Off-site remediations are not
eligible for ARAR waivers, and all applicable substantive
and administrative requirements must be met. Depending
on a particular application, posttreatment (secondary
treatment) such as air sparging/SVE may be used in
conjunction with the in-situ metal-enhanced dechlorination
technology, requiring air emissions and effluent discharge
either on or off site. CERCLA requires on-site discharges
to meet all substantive state and federal ARARs, such as
effluent standards. Off-site discharges must comply not
only with substantive ARARs, but also state and federal
administrative ARARs, such as permitting, designed to
facilitate implementation of the substantive requirements.
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Table 3-1. Summary of Environmental Regulations
Act/Authority Applicability
Application to the In-Situ Metal-Enhanced
Dechlorination Technology
Citation
CERCLA
RCRA
CWA
SDWA
CAA
Cleanups at
Superfund sites
This program authorizes and regulates the 40 CFR part 300
cleanup of releases of hazardous
substances. It applies to all CERCLA site
cleanups and requires that other
environmental laws be considered as
appropriate to protect human health and the
environment.
RCRA regulates the transportation,
treatment, storage, and disposal of
hazardous wastes. RCRA also regulates
corrective actions at treatment, storage, and
disposal facilities.
NPDES requirements of CWA apply to both
Superfund and RCRA sites where treated
water is discharged to surface water bodies.
Pretreatment standards apply to discharges
toPOTWs. These regulations do not
typically apply to in-situ technologies.
Maximum contaminant levels and
contaminant level goals should be
considered when setting water cleanup
levels at RCRA corrective action and
Superfund sites. Sole sources and
protected wellhead water sources would be
subject to their respective control programs.
Air emissions from If VOC emissions occur or hazardous air
stationary and pollutants are of concern, these standards
mobile sources may be applicable to ensure that use of this
technology does not degrade air quality.
State air program requirements also should
be considered.
Cleanups at
Superfund and
RCRA sites
Discharges to
surface water
bodies
Water discharges,
water reinjection,
and sole-source
aquifer and
wellhead
protection
40 CFR parts 260 to
270
40 CFR parts 122 to
125, part 403
AEA and RCRA Mixed wastes
OSHA
All remedial
actions
NRC
All remedial
actions
40 CFR parts 141 to
149
40 CFR parts 50,
60, 61, and 70
AEA and RCRA requirements apply to the
treatment, storage, and disposal of mixed
waste containing both hazardous and
radioactive components. OSWER and DOE
directives provide guidance for addressing
mixed waste.
OSHA regulates on-site construction
activities and the health and safety of
workers at hazardous waste sites.
Installation and operation of the metal-
enhanced dechlorination process at
Superfund or RCRA cleanup sites must
meet OSHA requirements.
These regulations include radiation
protection standards for NRC-licensed
activities.
AEA (10 CFR part
60) and RCRA (see
above)
29 CFR parts 1900
to 1926
10 CFR part 20
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3.5.2 Resource Conservation and
Recovery Act
RCRA, as amended by the Hazardous and Solid Waste
Amendments of 1984, regulates management and disposal
of municipal and industrial solid wastes. EPA and the
states implement and enforce RCRA and state regulations.
Some of the RCRA Subtitle C (hazardous waste)
requirements under 40 CFR parts 264 and 265 may apply
at CERCLA sites because remedial actions generally
involve treatment, storage, or disposal of hazardous waste.
However, RCRA requirements may be waived for
CERCLA remediation sites, provided equivalent or more
stringent ARARs are followed.
Use of the in-situ metal-enhanced dechlorination
technology may constitute "treatment" as defined under
RCRA regulations in Title 40 of the Code of Federal
Regulations (40 CFR) 260.10. Because treatment of a
hazardous waste usually requires a permit under RCRA,
permitting requirements may apply if the technology is
used to treat a listed or characteristic hazardous waste.
Regulations in 40 CFR part 264, subpart X, which regulate
hazardous waste storage, treatment, and disposal in
miscellaneous units, may be relevant to the metal-
enhanced dechlorination process. Subpart X requires that
in order to obtain a permit for treatment in miscellaneous
units, an environmental assessment must be conducted to
demonstrate that the unit is designed, operated, and closed
in a manner that protects human health and the
environment. Requirements in 40 CFR part 265, subpart Q
(Chemical, Physical, and Biological Treatment), could
also apply. Subpart Q includes requirements for waste
analysis and trial tests. RCRA also contains special
standards for ignitable or reactive wastes, incompatible
wastes, and special categories of waste (40 CFR parts 264
and 265, subpart B). These standards may apply to the in-
situ metal-enhanced dechlorination technology, depending
on the waste to be treated.
In the event the in-situ metal-enhanced dechlorination
technology is used to treat contaminated liquids at
hazardous waste treatment, storage, and disposal facilities
as part of RCRA corrective actions, regulations in 40 CFR
part 264, subparts F and S may apply. These regulations
include requirements for initiating and conducting RCRA
corrective actions, remediating groundwater, and operating
corrective action management units and temporary units
associated with remediation operations. In states
authorized to implement RCRA, additional state
regulations more stringent or broader in scope than federal
requirements must also be addressed.
Most RCRA regulations affecting conventional treatment
technologies will not apply to the in-situ metal-enhanced
dechlorination technology because once installed,
properly designed and maintained systems generate no
residual waste. However, during installation activities, the
excavation of a trench and removal of soil from the
saturated zone is required. Many chlorinated solvents are
RCRA "F-listed" wastes; therefore, at sites where
groundwater is contaminated with these compounds, soils
removed from the saturated zone may also contain F-listed
contaminants and be classified as hazardous waste. If so,
these soils will require management, including storage,
shipment, and disposal, following RCRA guidelines.
Active industrial facilities generating hazardous waste are
required to have designated hazardous waste storage
areas, and most operate under 90-day storage permits. A
facility's storage area could be used as a temporary storage
area for contaminated soils generated during the
installation of the in-situ metal-enhanced dechlorination
technology. For nonactive facilities, or those not
generating hazardous waste (as in the case of the site where
the New York demonstration occurred), a temporary
storage area should be constructed on site following
RCRA guidelines, and a temporary hazardous waste
generator identification number should be obtained from
the regional EPA office. Guidelines for hazardous waste
storage are listed under 40 CFR parts 264 and 265. Also,
water removed from the excavation may require
management as a hazardous waste. Tank storage of liquid
hazardous waste must meet the requirements of 40 CFR
part 264 or 265, subpart J.
The reactive iron may require occasional physical or
chemical treatment to remove entrapped solids or
precipitates from the reactive iron medium. Portions of
the influent side of the reactive iron may be periodically
replaced. For in-situ systems, methods for treating or
replacing the iron are still under evaluation at the time of
this report, and therefore the exact methods that will be
used are unknown at this time. If these actions occur,
removed water, soil, or reactive iron may be RCRA
hazardous wastes, and RCRA requirements for hazardous
waste disposal (see 40 CFR parts 264 and 265) may apply.
However, iron removed from the aboveground reactor
during a previous SITE Program demonstration in New
Jersey was tested for residual contamination. The iron was
determined to be nonhazardous and did not require
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management as a RCRA hazardous waste, and was
subsequently sold as scrap metal.
Although not typically required, if secondary treatment is
used in conjunction with the in-situ metal-enhanced
dechlorination process, additional RCRA regulations may
apply. If secondary treatment involves extraction and
treatment of groundwater, and the groundwater is
classified as hazardous waste, the treated groundwater
must meet treatment standards under land disposal
restrictions (LDR) (40 CFR part 268) before reinjection or
placement on the land (for example, in a surface
impoundment).
RCRA parts 264 and 265, subparts AA, BB, and CC
address air emissions from hazardous waste treatment,
storage, and disposal facilities. These regulations would
probably not apply directly to the in-situ metal-enhanced
dechlorination technology, but may apply to the overall
process if it incorporates secondary treatment, such as air
sparging/SVE. Subpart AA regulations apply to organic
emissions from process vents on certain types of
hazardous waste treatment units. Subpart BB regulations
apply to fugitive emissions (equipment leaks) from
hazardous waste treatment, storage, and disposal facilities
that treat waste containing organic concentrations of at
least 10 percent by weight. Many organic air emissions
from hazardous waste tank systems, surface impoundments,
or containers will eventually be subject to the air emission
regulations in 40 CFR parts 264 and 265, subpart CC.
Presently, EPA is deferring application of the Subpart CC
standards to waste management units used solely to treat
or store hazardous waste generated on site from remedial
activities required under RCRA corrective action or
CERCLAresponse authorities (or similar state remediation
authorities). Therefore, Subpart CC regulations may not
immediately impact implementation of the in-situ metal-
enhanced dechlorination technology or associated
secondary treatment technologies used in remedial
applications. EPA may remove this deferral in the future.
3.5.3 Clean Water Act
The Clean Water Act (CWA) governs discharge of
pollutants to navigable surface water bodies or publicly-
owned treatment works (POTW) by providing for the
establishment of federal, state, and local discharge
standards. Because the in-situ metal-enhanced
dechlorination technology does not normally result in
extraction and discharge of contaminated groundwater to
surface water bodies or POTWs, the CWA would not
typically apply to the normal operation and use of this
technology.
3.5.4 Safe Drinking Water Act
The Safe Drinking Water Act (SDWA), as amended in
1986, required EPA to establish regulations to protect
human health from contaminants in drinking water. EPA
has developed the following programs to achieve this
objective: (1) a drinking water standards program, (2) an
underground injection control program, and (3) sole-
source aquifer and wellhead protection programs.
SDWA primary (health-based) and secondary (aesthetic)
MCLs generally apply as cleanup standards for water that
is, or may be, used as drinking water. In some cases, such
as when multiple contaminants are present, more stringent
MCL goals may be appropriate. During the SITE
demonstration, the in-situ metal-enhanced dechlorination
process's performance was evaluated to determine its
compliance with SDWA MCLs and NYSDEC standards
for several critical VOCs. The results indicated that
effluent concentrations met MCLs during all months of
testing after system performance stabilized; four out of 90
critical parameter measurements slightly exceeded
NYSDEC limits in the same period.
Water discharge through injection wells is regulated by the
underground injection control program. The technology
does not require extraction and reinjection of groundwater;
therefore, regulations governing underground injection
programs would not typically apply to this technology.
The sole-source aquifer and wellhead protection programs
are designed to protect specific drinking water supply
sources. If such a source is to be remediated using the in-
situ metal-enhanced dechlorination technology, appropriate
program officials should be notified, and any potential
regulatory requirements should be identified. State
groundwater antidegradation requirements and water
quality standards (WQS) may also apply.
3.5.5 Clean Air Act
The Clean Air Act (CAA), as amended in 1990, regulates
stationary and mobile sources of air emissions. CAA
regulations are generally implemented through combined
federal, state, and local programs. The CAA includes
pollutant-specific standards for major stationary sources
57
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that would not be ARARs for the in-situ metal-enhanced
dechlorination process, and would apply only if auxiliary
treatment (such as air sparging/SVE) were employed.
State and local air programs have been delegated
significant air quality regulatory responsibilities, and
some have developed programs to regulate toxic air
pollutants (EPA 1989). Therefore, state air programs
should be consulted regarding secondary treatment if used
in conjunction with this technology.
3.5.6 Mixed Waste Regulations
Use of the in-situ metal-enhanced dechlorination
technology at sites with radioactive contamination might
involve treatment of mixed waste. As defined by the
Atomic Energy Act (AEA) and RCRA, mixed waste
contains both radioactive and hazardous waste components.
Such waste is subject to the requirements of both acts.
However, when application of both AEA and RCRA
regulations results in a situation that is inconsistent with
the AEA (for example, an increased likelihood of
radioactive exposure), AEA requirements supersede
RCRA requirements (EPA 1988a). OSWER, in
conjunction with the Nuclear Regulatory Commission
(NRC), has issued several directives to assist in
identification, treatment, and disposal of low-level
radioactive mixed waste. Various OSWER directives
include guidance on defining, identifying, and disposing
of commercial, mixed, low-level radioactive, and
hazardous waste (EPA 1988b). If the in-situ metal-
enhanced dechlorination process is used to treat
groundwater containing low-level mixed waste, these
directives should be considered, especially regarding
contaminated soils excavated during installation. If high-
level mixed waste or transuranic mixed waste is treated,
internal DOE orders should be considered when
developing a protective remedy (Department of Energy
[DOE] 1988). The SDWA and CWA also contain
standards for maximum allowable radioactivity levels in
water supplies.
3.5.7 Occupational Safety and Health
Act(OSHA)
OSHA regulations in 29 CFR parts 1900 through 1926 are
designed to protect worker health and safety. Both
Superfund and RCRA corrective actions must meet OSHA
requirements, particularly ง1910.120, Hazardous Waste
Operations and Emergency Response. Part 1926, Safety
and Health Regulations for Construction, applies to any
on-site construction activities. For example, excavation of
the trench for placement of the reactive iron medium
during the demonstration was required to comply with
regulations in 29 CFR part 1926, subpart P. Any more
stringent state or local requirements must also be met. In
addition, health and safety plans for site remediation
projects should address chemicals of concern and include
monitoring practices to ensure that worker health and
safety are maintained.
3.6 State and Community Acceptance
State regulatory agencies will likely be involved in most
applications of the metal-enhanced dechlorination process
at hazardous waste sites. Local community agencies and
citizen's groups are often also actively involved hi
decisions regarding remedial alternatives.
Because few applications of the metal-enhanced
dechlorination technology have been completed, limited
information is available to assess long-term state and
community acceptance. However, state and community
acceptance of this technology is generally expected to be
high, for several reasons: (1) relative absence of intrusive
surface structures that restrict use of the treatment area; (2)
absence of noise and air emissions; (3) the system is
capable of significantly reducing concentrations of
hazardous substances in groundwater; and (4) the system
generates no residual wastes requiring off-site management
and does not transfer waste to other media.
NYSDEC oversees investigation and remedial activities at
the New York site. State personnel were actively involved
in the preparation of the work plan for the demonstration
of the pilot-scale funnel and gate system and monitored
system construction and performance. NYSDEC will also
be actively involved in planning for any full-scale systems
installed at the site. The role of states in selecting and
applying remedial technologies will likely increase in the
future as state environmental agencies increasingly
assume many of the oversight and enforcement activities
previously performed at the EPA Regional level. For these
reasons, state regulatory requirements that are sometimes
more stringent than federal requirements may take
precedence for some applications. Also, as risk-based
closure and remediation become more commonplace, site-
specific cleanup goals determined by state agencies will
drive increasing numbers of remediation projects,
including applications involving the metal-enhanced
dechlorination technology.
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Section 4
Economic Analysis
This economic analysis presents cost estimates for using
an in-situ application of the metal-enhanced dechlorination
technology to treat contaminated groundwater. Costs are
presented for two full-scale options: 1) a continuous,
reactive iron wall; and 2) a funnel and gate system. The
cost estimates are based on systems designed to treat the
types and concentrations of chlorinated VOCs observed at
the New York demonstration site. The estimates are based
on data compiled during the SITE demonstration and from
additional information obtained from ETI, S&W, current
construction cost estimating guidance, independent
vendors, and SITE Program experience.
Past studies by ETI have indicated that costs for this
technology are highly variable and are dependent on the
types and concentrations of the contaminants present,
dimensions of the contaminant plume, site hydrogeology,
regulatory requirements, and other site-specific factors.
Estimates for total cost and cost per gallon of water treated
are also heavily influenced by assumptions regarding the
duration of the treatment program and the cumulative
volume treated. Furthermore, it is important to note that
the cost data presented in this report are partially based on
extrapolations from design and operating parameters for
the pilot-scale system evaluated during the SITE
demonstration. The purpose of the pilot-scale system was
to determine the optimal design and operating parameters
for a full-scale system. Differences between the
capabilities of New York pilot-scale system and full-scale
systems designed for optimal performance at other sites
could cause actual costs to vary significantly from
estimates presented in this report.
Cost data are presented in terms of total cost and cost per
gallon of water treated to facilitate comparison of costs
with other treatment technologies. However, for passive
in-situ systems, the cumulative volume treated is limited
by the natural groundwater flow velocity, and cost per
gallon may not always reflect the technology's overall
value. The in-situ metal-enhanced dechlorination process
combines the ability to remediate groundwater with
features typically associated with containment systems;
under optimal operating conditions, the technology
prevents migration of contaminated groundwater toward
potential receptors by treating water passing through it.
The technology could be combined with source reduction
activities to enhance an overall remedial program at a site.
Due to the many factors that potentially affect the cost of
using this technology, several assumptions were necessary
to prepare the economic analysis. Several of the most
significant of these assumptions are: (1) a continuous,
reactive iron wall is assumed to be best-suited for this
particular application; however, cost estimates for a funnel
and gate system are also provided for comparison; (2) the
system will treat water contaminated with TCE, cDCE,
and VC at concentrations observed during the SITE
demonstration; and (3) the system will treat groundwater
for 20 years. (This assumption requires extrapolation of
some SITE demonstration data to the longer operating
period.)
The 20-year timeframe was selected for consistency with
cost evaluations of other innovative technologies
evaluated by the EPA SITE Program, and because it
facilitates comparison to typical costs associated with
conventional, long-term remedial options. The timeframe
does not reflect any estimate of the actual time required to
remediate groundwater at the New York site.
This section summarizes site-specific factors that
influence costs, presents assumptions used in this analysis,
discusses estimated costs, and presents conclusions of the
economic analysis. Tables 4-1 and 4-2 present the
estimated costs generated from this analysis. Costs have
been distributed among 12 categories applicable to typical
cleanup activities at Superfund and RCRA sites (Evans
1990). Costs are presented hi 1996 dollars, are rounded to
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Table 4-1. Estimated Costs Associated with the Metal-Enhanced Dechlorination Technology: Continuous Wall System
Cost Category
Cost
Total Cost
Site Preparation11
Administrative $15,700
Treatability study 20,000
System design 10,000
Excavation and backfill 152,500
Monitoring wells 6,100
Soil and Water Disposal 64,300
Permitting and Regulatory"
Mobilization and Startup"
Capital Equipment"
Reactive Iron 135,000
Sampling Equipment 8,000
Demobilization"
Total Estimated Fixed Costs
Labor (Sampling and Routine O&M)C
Supplies0
PPE $300
Carbon Canisters 700
Sampling equipment 1,000
Utilities0
Effluent Treatment and Disposal0
Residual Waste Handling0
Analytical Services0
Equipment Maintenance0'*
Total Estimated Variable (Annual) Costs
Total Estimated Fixed and Variable
Costs After 20 Years8
Costs per 1,000 gallons treated'
Costs per gallon treated1
$268,600
Notes:
4,000
40,000
143,000
$11,000
$466,600
$5,500
2,000
0
0
0
9,300
4,100
$20,900
$884,600
$18.02
$0.018
AH costs presented in 1996 dollars.
* Costs estimated based on data from SITE demonstration and other sources.
" Fixed costs.
0 Variable costs, presented as annual total.
d Annual total prorated from expense incurred at 7-year intervals.
Total costs after 20 years of operations; all annual costs multiplied by 20, plus
total fixed costs.
f Total of 49.1 million gallons of groundwater treated.
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Table 4-2. Estimated Costs Associated with the Metal-Enhanced Dechlorination Technology: Funnel and Gate System
Cost Category
Cost
Site Preparation"
Administrative $15,700
Treatability study 20,000
System design 10,000
Funnel and Gate Construction 266,000
Monitoring wells 6,100
Soil and Water Disposal 64,300
Permitting and Regulatoryb
Mobilization and Startup"
Capital Equipment"
Reactive Iron 135,000
Sampling Equipment 8,000
Demobilization"
Total Estimated Fixed Costs
Labor (Sampling and Routine O&M)C
Supplies0
PPE
Carbon Canisters
Sampling equipment
Utilities0
Effluent Treatment and Disposal0
Residual Waste Handling0
Analytical Services0
Equipment Maintenance0'4
Total Estimated Variable (Annual) Costs
Total Estimated Fixed and Variable
Costs After 20 Years e
Costs per 1,000 gallons treated'
Costs per gallon treated'
$300
700
1,000
Notes:
Total Cost
$382.100
4,000
32,500
143,000
$11.000
$572,600
$5,500
2,000
0
0
0
9,300
2,700
$19,500
$962,600
$19.60
$0.020
All costs presented in 1996 dollars.
a Costs estimated based on data from SITE demonstration and other sources.
" Fixed costs.
0 Variable costs, presented as annual total.
d Annual total prorated from expense incurred at 7-year intervals.
e Total costs after 20 years of operations; all annual costs multiplied by 20, plus
total fixed costs.
f Total of 49.1 million gallons of groundwater treated.
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the nearest 100 dollars, and are considered to be order-of-
magnitude estimates.
4.1 Factors Affecting Costs
Costs for implementing this technology are significantly
affected by site-specific factors, including site regulatory
status, waste-related factors, and site features. The
regulatory status of the site typically depends on the type
of waste management activities that occurred on site, the
relative risk to nearby populations and ecological
receptors, the state in which the site is located, and other
factors. The site's regulatory status affects costs by
mandating ARAR's and remediation goals that may affect
the system design parameters and duration of the
remediation project. Certain types of sites may have more
stringent monitoring requirements than others, depending
on regulatory status.
Waste-related factors affecting costs include contaminant
plume size and geometry; contaminant types and
concentrations, andregulatory agency-designated treatment
goals. Plumes that cover extensive areas will require
longer walls or more funnels and gates to achieve
hydraulic control, and may take longer to pass through the
treatment system. Larger contaminant masses (plume
volume times contaminant concentration) require greater
amounts of reactive iron.
The contaminant types and concentrations in the
groundwater determine contaminant half-lives. The
required residence time in the iron, which determines the
appropriate width for the reactive iron zone and affects
capital equipment costs and construction costs, is based on
the contaminant half-lives, the remediation goals, and the
groundwater flow velocity. The types of contaminants and
the remediation goals may also determine the need for
auxiliary in-situ treatment systems and will influence
performance monitoring requirements.
Site features affecting costs include site hydrogeology
(geologic features and groundwater flow rates),
groundwater chemistry (for example, concentrations of
inorganic substances), and site location and physical
characteristics. Hydrogeologic conditions are significant
factors in determining the applicability and design
parameters, and thus the costs, of in-situ applications of
the metal-enhaaced dechlorination process, and should be
thoroughly defined before applying this technology. The
saturated thickness determines the required height of the
reactive iron wall. The groundwater flow velocity
determines the thickness of the iron wall required to allow
sufficient residence time for dechlorination to occur.
These factors (along with the dimensions of the
contaminant plume) determine the necessary volume of
iron and trench dimensions. The depth to water and the
depth to the uppermost underlying aquitard determine the
depth of the installation and the type of construction
technology that will be employed. All of these factors
affect capital equipment costs and site preparation costs.
Also, since this is a passive technology, the groundwater
flow velocity and saturated thickness will control
volumetric flow through the system, influencing the
duration of the remediation project and time-ielated
variable costs, such as analytical and maintenance costs.
Groundwater chemistry can also affect costs. High
concentrations of dissolved inorganic substances in
influent groundwater may result in precipitation of
compounds such as calcium carbonate, particularly on the
upper/influent side of the iron, requiring more frequent
maintenance.
Site location and physical features will impact
mobilization, demobilization, and site preparation costs.
Mobilization and demobilization costs are affected by the
relative distances that system materials must travel to the
site. Sites requiring extensive surficial preparation (such
as constructing access roads, clearing large trees, working
around or demolishing structures) or restoration activities
will also incur higher costs.
Depending on the type of system installed, the availability
of existing electrical power and water supplies may
facilitate construction activities. However, unlike many
conventional technologies, system operation typically
requires no utilities. For these reasons, utilities are
typically not a significant factor affecting costs for this
technology.
4.2 Assumptions Used in Performing
the Economic Analysis
This section summarizes major assumptions regarding
site-specific factors and equipment and operating
parameters used in this economic analysis. Certain
assumptions were made to account for variable site and
waste parameters. Other assumptions were made to
simplify cost estimating for situations that actually would
require complex engineering or financial functions. In
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general, most system operating issues and assumptions are
based on information provided by ETI, S&W, and
observations made during the SITE demonstration. Cost
figures are established from information provided by ETI
(ETI 1996b; 1996d), S&W (1994), current environmental
restoration cost guidance (R.S. Means [Means] 1996), and
SITE Program experience.
Assumptions regarding site- and waste-related factors
include the following:
The site is a Superfund site, located in the north-
eastern U.S.
Site groundwater is contaminated with TCE,
cDCE, and VC at maximum concentrations of
about 300 jxg/L, 500 ug/L, and 100 ug/L, respec-
tively.
The cleanup goals are federal MCL requirements
of 5 ug/L for both TCE and cDCE, and 2 ug/L for
VC.
The site is located in a rural area, but is easily ac-
cessible to standard (wheel-mounted) heavy equip-
ment.
Contaminated water is located in a shallow aqui-
fer that overlies a dense, silty clay aquitard at a
depth of 15 feet bgs.
The aquifer is a moderately permeable sand and
gravel aquifer, with a natural horizontal flow ve-
locity of 0.75 foot per day. The seasonal saturated
thickness varies from about 10 to 12 feet.
The groundwater contaminant plume is 300 feet
wide.
The site has no existing structures requiring demo-
lition and does not require extensive clearing.
There are no existing utilities on site that require
relocation or restrict operation of heavy equipment
such as excavators, cranes, or drill rigs.
Typical naturally occurring inorganic substances
are present in site groundwater, but do not result
in excessively rapid precipitate buildup.
Assumptions regarding treatment system design and
operating parameters include the following:
A continuous iron wall will be used for this appli-
cation. However, costs for an alternative three-
gate runnel and gate system are presented for com-
parison.
The hydraulic conductivity of the iron is assumed
to be 142 feet per day; the porosity is assumed to
be 0.4. The groundwater flow velocity through
the continuous iron wall is assumed to be about
the same as for the natural aquifer materials, 0.75
foot per day. Based on these parameters, the plume
dimensions, and the saturated thickness, the wall
will be 300 feet long, 12.5 feet high, and 1.0 foot
thick, and will require about 337.5 tons of iron
(ETI 1996b; 1996d).
If a funnel and gate system is used, the system
would consist of three gates, each about 20 feet
wide. Total system length (including sheet pile
funnels) would be 440 feet. According to ETI, run-
nel and gate systems significantly accelerate flow
velocities and would treat about the same volume
of water and the same contaminant mass flux as
the continuous wall. For this reason, ETI estimates
that the combined total mass of iron used for the 3
gates would be the same as the minimum recom-
mended for the continuous wall (about 337.5 tons),
resulting in each gate having a 5-foot-thick iron
wall (ETI 1996d).
The minimum volume of groundwater that will
pass through the continuous wall or through the
funnel and gate system during the remediation
project is assumed to be 49.1 million gallons, as-
suming the flow velocity, porosity, and hydraulic
conductivity remain constant.
ETI will provide a representative as an on-site con-
sultant for key phases of the construction.
The system continually treats groundwater for 20
years. No downtime is required for periodic main-
tenance.
The system continues to achieve cleanup goals
over the remediation period. For this reason, and
because the treatment system operates in-situ, there
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are no additional effluent management require-
ments, such as air sparging.
After construction, the treatment system operates
without the constant attention of an operator. Rou-
tine labor requirements consist of monthly sam-
pling, measurement of water levels, inspection of
the monitoring wells and ground surface above the
system, and mowing the area above the system.
Periodic maintenance may consist of using soil
mixing equipment to agitate the upgradient side
of the iron wall every 5 to 7 years. However, the
effectiveness and feasibility of this technique is
undocumented at this time.
All system components are below grade, so no
anti freezing measures are required.
All equipment and supplies are mobilized from
within 500 miles of the site, or less.
Monthly samples of upgradient (influent) and
downgradient (effluent) groundwater will be re-
quired for the first 6 months after installation. After
this period, quarterly samples will be required, for
20 years.
Depreciation is not considered in order to simplify
presenting the costs of this analysis.Most groundwater
remediation projects are long-term in nature, and usually a
net present worth analysis is performed for cost
comparisons. However, the variable costs for this
technology are relatively low, and no other system
configurations or technologies are presented in this
analysis for comparison. For these reasons, annual costs
arc not adjusted for inflation, and no net present value is
calculated.
4.3 Cost Categories
Table 4-1 presents cost breakdowns for each of the 12 cost
categories for the continuous wall. Data have been
presented for the following cost categories: (1) site
preparation, (2) permitting and regulatory, (3) mobilization
and startup, (4) capital equipment, (5) labor, (6) supplies,
(7) utilities, (8) effluent treatment and disposal, (9) residual
waste shipping and handling, (10) analytical services,
(11) equipment maintenance, and (12) site demobilization.
Because costs for a funnel and gate system would probably
be different than those associated with a continuous wall,
Table 4-2 presents the costs for a three-gate funnel and gate
system treating the same size and type of contaminant
plume as the continuous wall. Each of the 12 cost
categories are discussed below.
4.3.1 Site Preparation Costs
Site preparation costs include administration costs, costs
for conducting a bench-scale treatability study, conducting
engineering design activities, and preparing the treatment
area. Site preparation also includes costs associated with
constructing the continuous wall or funnel and gate system
and making the system operational, with the exception of
mobilization charges for specialized heavy construction
equipment (see Section 4.3.3) and the cost of the iron
medium (see Section 4.3.4).
Administrative costs include costs for legal searches,
contracting, and general project planning activities.
Administrative costs are highly site-specific; for this
estimate, administrative costs are assumed to be $12,500,
or about 200 hours of technical staff labor at $50 per hour
and 100 hours of administrative staff labor at $25 per hour
(Means 1996). Also, ETI typically charges a site license
fee equal to 15 percent of the iron costs (see Section 4.3.4).
For either the full-scale continuous wall or funnel and gate
systems, ETI's site license fee is estimated to be about
$3,200.
According to ETI and S&W, a phased treatability study
will take between 2 to 4 months to complete (see Section 5
for a discussion of the four phases used to implement the
technology). Treatability study costs include expenses for
column tests and labor. According to ETI, typical
analytical laboratory costs for column tests for a project
similar to the one at this site will be about $15,000. The
labor for the treatability study will be about $5,000,
inclusive of 100 hours at an average rate of $50 per hour.
The total cost of a treatability study will be about $20,000
(EPA 1997).
After the study and a site assessment, ETI will assist in the
design of an optimal system configuration for a particular
site. The total system design costs are estimated to be about
$10,000. This cost includes about 130 labor hours at an
average rate of $75 per hour (Means 1996). This estimate
assumes that site hydrogeology has already been
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thoroughly characterized, and no additional hydrogeologic
data will be required. If additional hydrogeologic studies
are required, design costs could be higher.
Treatment area preparation costs depend on the type of
system used. ETI estimates that for a site having the same
waste and site features as the New York site, a continuous
reactive iron wall may be the most cost effective type of
system (ETI 1996d). Costs for a continuous wall include
excavating a trench, backfilling it with reactive iron,
disposing of the displaced soil, and installing a
groundwater monitoring system. This estimate assumes
that a continuous trenching/backfill technique will be used
to excavate the trench and emplace the iron, eliminating
the need for shoring. Before excavating the trench, soil
from above the saturated zone (this estimate assumes the
upper 3 feet of native soil) can be excavated with a
conventional backhoe, stockpiled on site, and eventually
replaced to form a cover over the iron, at an assumed cost
of about $2,000 (Means 1996).
After the top 3 feet of soil are removed, the trench will be
extended down to the top of the underlying clay layer, in
this case assumed to be 15 feet below ground surface, using
continuous trenching/backfilling equipment. The
equipment will continuously excavate and backfill each
section of trench with iron, up to about 2.5 feet below
grade, continuing until the 300-foot long iron wall is
completed. According to ETI, at this depth, it is possible to
construct about 100 to 200 lineal feet of reactive iron wall
per day using this technique. Costs for the excavation/
backfill equipment and operator are estimated to be
$150,500, not including mobilization (see Section 4.3.3).
(This figure includes costs for transferring soil to roll-off
boxes as the trench is excavated.) Total trench
construction costs are estimated to be $152,500, not
including the costs of the reactive iron (see Section 4.3.4)
(Means 1996; ETI 1996d).
After all of the iron is emplaced and settled, the top of the
wall will be about 3 feet bgs. The stockpiled native soil
from the upper part of the excavation, which will not have
contacted contaminated groundwater, will be used to fill
the upper part of the trench. Soil excavated from the lower
portion of the trench (below the water table) will have
contacted groundwater contaminated with RCRA F-listed
solvents and may require management as a hazardous
waste. This cost estimate assumes that the soil will be
loaded into roll-off containers, stored on site pending
characterization, and shipped offsite and disposed of as a
hazardous waste. Based on the dimensions of the trench
for the continuous wall (and the volume of soil displaced
by monitoring well construction), about 140 cubic yards of
soil will require disposal. Assuming a disposal cost of
$400 per cubic yard (landfill disposal), transport costs of
$3.30 per mile for each roll-off container, characterization
and manifesting fees of $5000, and disposal at a location
100-miles from the site, total costs for managing this
material are estimated to be about $62,300. Actual costs
for waste disposal are highly site specific, and may vary
substantially from this estimate, particularly if the soil
requires incineration (Means 1996).
Alternatively, if a funnel and gate configuration is used,
ETI estimates that a three-gate, 440-foot-long system
would capture the 300-foot-wide plume. Each gate would
be constructed using the same general techniques used for
the pilot-scale system demonstrated at the New York site
(see Section 1). Site preparation costs would include costs
for excavating and backfilling the three 20-foot-wide gates
with a reactive iron section bordered by pea gravel and
installing the sheet-piling to form the continuous funnel.
ETI estimates construction and material costs (including
sheet piling, but not including the reactive iron) to be
$264,000 for this system (ETI 1996d). For estimating
purposes, topsoil removal and replacement, soil disposal,
and all other site preparation costs are assumed to be the
same as for the continuous wall.
A groundwater monitoring system will be required to
monitor system performance. For a continuous wall, this
estimate assumes that the system will require a well
spacing of no more than 50 feet along the downgradient
side of the wall, to ensure that all sections of the wall are
performing adequately. Three upgradient wells will also
be installed to allow determination of the system's
removal efficiency. Installation and development of nine,
15-foot-deep PVC monitoring wells with locking caps and
flush-mounted protective casings will be required. The
assumed cost for these wells is $45 per foot (including drill
rig mobilization from within 50 miles of the site), for a total
cost of about $6,100. Auger cuttings (about 2 cubic yards)
will be disposed of with the material from the trench; costs
for this were included in the waste disposal costs
previously discussed.
For a funnel and gate system, this estimate assumes that
one upgradient well and two downgradient wells would be
constructed in the pea gravel zones at each gate. It may be
possible to install these wells at the time of construction,
eliminating the need for drilling. However, at a minimum,
the wells will require bracing and completion methods
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similar to those used during the SITE demonstration, so for
estimating purposes, construction costs for these wells are
also assumed to be $45 per lineal foot,,for a total of $6,100.
Water from monitoring well development (or from trench
dewatering activities for a funnel and gate system) will
contain site contaminants. This estimate assumes that the
water can be passed through a carbon filter and discharged
to the ground surface upgradient from the system. Costs
for this method of disposal are assumed to be about $2,000,
including the cost of carbon canisters and labor.
All system components will be completed below grade.
The wells will have locking inner caps. For this reason, no
costs for additional security (fences) will be incurred.
For a continuous iron wall, total site preparation costs are
estimated to be $268,600; for a funnel and gate system, site
preparation costs are assumed to be $382,100.
4.3.2 Permitting and Regulatory Costs
Permitting and regulatory costs are highly site-specific and
will depend on whether treatment is performed at a
Superfund or a RCRA corrective action site; wellhead
protection area restrictions; and other factors. Superfund
site remedial actions must be consistent with ARARs of
environmental laws, ordinances, regulations, and statutes,
including federal, state, and local standards and criteria.
Remediation at RCRA corrective action sites requires
additional monitoring and record keeping, which can
increase the base regulatory costs.
The cost of all permits is based on the effluent
characteristics and related receiving water requirements.
For this analysis, groundwater is not extracted before
treatment, so the costs assume that no permit for discharge
of treated effluent to the aquifer will be required. (This
assumption is based on ETI's experience at several full-
scale installations in the U.S.). For this reason, this
estimate assumes that total permitting and regulatory costs
are minimal; about $4,000. This includes 50 hours of labor
at $75 per hour, and $250 for miscellaneous expenses such
as fees and reproduction costs.
4.3.3 Mobilization and Startup Costs
Mobilization and startup costs consist of mobilizing the
construction equipment and materials and delivering the
reactive iron. However, unlike conventional aboveground
systems, no additional assembly charges are incurred
beyond the construction costs described in Section 4.3.1.
The technology requires no electrical power, water supply,
or other utilities. For in-situ applications of this
technology, mobilization and startup costs are assumed to
consist solely of equipment mobilization charges.
Mobilization costs will vary depending on the location of
the site in relation to suppliers. Based on information
provided by ETI, mobilization of the specialized
construction equipment for a continuous wall (to a site, in
the northeastern U.S.) is assumed to be $40,000. For a
funnel and gate system, equipment mobilization is
assumed to be $32,500.
For the site where the demonstration of the aboveground
reactor occurred, which was also in the northeastern U.S.,
ETI estimated that iron transportation costs would be
about $75 per ton, or about 14 percent of the cost of the iron
(EPA 1997). ETI's current estimates for the cost of the
iron include delivery costs (see Section 4.3.4); for this
reason, iron delivery charges are not listed as a separate
item in Tables 4-1 and 4-2. However, costs for the iron will
be influenced by the site's location in relation to the
supplier, the distance the iron must be transported to the
site, the mode of packaging (bulk, drums, or 1-cubic yard
"totes"), and the mode of transportation. For this reason,
iron costs may vary on a site-specific basis.
4.3.4 Capital Equipment Costs
Capital equipment costs for this analysis include the cost of
the reactive iron and groundwater monitoring equipment.
Costs for other materials (monitoring wells, sheet piling
funnels, etc.) were previously discussed in Section 4.3.1
and are not considered to be capital equipment costs for
this estimate.
ETI configures the complete treatment system based on
site-specific conditions. According to ETI, current costs
for the reactive iron, including delivery to a site in the
northeastern U.S., are about $400 per ton, assuming truck
delivery of iron in bulk form. (However, costs may vary on
a site-specific basis.) ETI estimates that the typical iron
density after settling is about 180 pounds per cubic foot
(0.09 ton per cubic foot). Based on this estimate, the
3,750-cubic-foot continuous wall will require about 337.5
tons of reactive iron, resulting in a total capital equipment
cost of about $135,000. According to ETI, the same
amount of iron would be required for a funnel and gate
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system, as the system would treat the same volume of
contaminated groundwater as the continuous wall.
For either system, equipment that will be required to
monitor the technology's performance includes a low-
flow sampling pump and meters to measure pH, Eh, and
other field parameters. Because this is a long-term project
purchasing these items will probably be more cost
effective than renting them. This estimate assumes that
these items will cost about $8,000.
Total capital equipment costs are estimated to be $ 143,000
for either the continuous wall or the funnel and gate
system.
4.3.5 Labor Costs
Once the system is functioning, it is assumed to operate
unattended and continuously except during routine O&M,
monitoring, and sampling activities.
Routine O&M will generally consist of mowing the area
over and around the treatment system (to prevent
establishment of deep-rooted plants arid maintain access to
the monitoring wells), inspecting the area for excessive
subsidence or erosion, and inspecting the condition of the
monitoring wells. Mowing could be contracted out at $50
per job, and would be required four times per year for an
annual cost of $200.
Inspection activities could be performed concurrently with
sampling. This cost estimate assumes that samples will be
collected monthly for the first 6 months after installation,
and then quarterly for the duration of the project. More
frequent monitoring is recommended immediately after
installation to ensure that the system is performing
according to design. This cost estimate assumes that all
sampling and analytical tasks will be performed by
independent contractors and labor costs for sampling are
$45 per hour (Means 1996). During each sampling event,
sampling personnel should also inspect the general
condition of the treatment system area and the condition of
the monitoring wells. Routine monitoring and sampling
activities are assumed to take about 16 hours per event,
assuming measurement of water levels and collection of
groundwater samples from nine monitoring wells,
laboratory coordination, and sample shipment. Data
interpretation and reporting will take an additional 12
hours per event. Based on these estimates total sampling-
related labor costs are $1,260 per sampling event. For a
20-year remediation project, estimated sampling labor
costs prorate to about $5,300 per year.
Total routine O&M and sampling costs are estimated to be
$5,500 per year. Laboratory analytical costs are presented
in Section 4.3.10, Analytical Services Costs. Other labor
requirements for periodic equipment maintenance (iron
replacement) and demobilization are presented in Section
4.3.11, Equipment Maintenance Costs and Section 4.3.12,
Site Demobilization Costs.
4.3.6 Supply Costs
Necessary supplies as part of the overall groundwater
remediation project include Level D disposable personal
protective equipment (PPE) and sampling and field
analytical supplies.
Disposable PPE typically consists of latex inner gloves,
nitrile outer gloves, and safety glasses. This PPE is used
during sampling activities. Disposable PPE is assumed to
cost about $300 per year for the sampler.
Water purged from the upgradient monitoring wells during
sampling activities should be contained. Based on the well
dimensions, purging the upgradient wells will generate
about 15 gallons of water per sampling event. This cost
estimate assumes that the water could be pumped through
a carbon filter at the completion of each sampling event
and discharged to the ground surface upgradient from the
system. This estimate assumes that carbon canisters will
require replacement annually, at a cost of $700 each,
including disposal/regeneration of the spent carbon
(Means 1996). If this is not feasible, additional off-site
disposal costs may be incurred. Because detectable
concentrations of contaminants are not anticipated to be
present in water downgradient from the system, this
estimate assumes that water purged from the downgradient
wells can be discharged to the ground surface.
Sampling supplies consist of sample bottles, shipping
containers, pump hoses or tubing, buckets or drums to
temporarily contain purge water, field meter calibration
solutions, and other typical groundwater : sampling
supplies. The numbers and types of necessary sampling
supplies are based on the analyses to be performed. For
this analysis, annual sampling supply costs are assumed to
be $1,000 (Means 1996). --. .....-
Total annual supply costs are estimated to be $2,000;
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4.3.7 Utility Costs
The in-situ metal-enhanced dechlorination system
typically requires no utilities.
4.3.8 Effluent Treatment and Disposal
Costs
This estimate assumes that the technology will reduce
groundwater contaminants to acceptable levels by in-situ
treatment. For this reason, no additional effluent treatment
and disposal costs will be incurred.
4.3.9 Residual Waste Shipping and
Handling Costs
Based on existing data, it appears that the dechlorination
process generates no residual wastes. This estimate
assumes that periodic maintenance to restore the iron's
hydraulic conductivity (see Section 4.3.11) will be
accomplished using in-situ soil mixing or a similar
process, and will not result in the generation of soil and
iron that requires management as a potentially hazardous
waste.
4.3.10 Analytical Services Costs
Analytical services costs include costs for laboratory
analyses, data reduction, and QA/QC. Required sampling
frequencies, number of samples, and associated QA/QC
requirements are highly site-specific and are based on
regulatory status, treatment goals, influent contaminant
concentrations, areal extent of the contaminant plume
(which determines the length of the iron wall or number of
gates), and other factors.
This analysis assumes that the number and frequency of
samples would be the same for either a continuous wall or
funnel and gate system; both cases assume that three
background wells and six downgradient wells will be
sampled during each event. All of the samples will be
analyzed for VOCs to directly monitor system
performance. The one background well and two
downgradient wells nearest the center of the wall will be
monitored for additional parameters to track inorganic
precipitation in the iron; bicarbonate alkalinity and metals
including calcium, magnesium, and iron, in addition to
VOCs. Based on typical costs for these analyses incurred
during the New York demonstration, costs for the VOC,
metals, and bicarbonate analyses are assumed to be $1507
sample, $100/sample, and $15/sample, respectively.
Analytical .costs also assume that one trip blank, one
matrix spike, and one matrix spike duplicate sample will
be submitted for VOC analyses during each event.
Geochemical parameters (pH, Eh, DO, conductivity, and
temperature) will be measured by sampling personnel in
the field using portable meters.
Assuming the sampling frequency discussed in Section
4.3.4 (monthly for the first six months and quarterly
thereafter) a total of 84 sampling events will be performed
over the 20-year project. Analytical costs for these events
prorate to about $9,000 annually.
Core samples of the reactive iron should be collected
periodically and analyzed to evaluate precipitate buildup.
This estimate assumes that one sample will be collected bi-
annually from the upgradient (influent) side of reactive
iron, and analyzed using wet chemistry techniques and by
microscopy. This estimate assumes that this sample could
be collected during routine sampling activities, and that the
analyses would cost about $600 per sample, prorating to
$300 per year.
Total annual analytical services costs are estimated to be
$9,300.
4.3.11 Equipment Maintenance Costs
Long-term data regarding the useful life of the reactive
iron are not available. ETI estimates that the iron may last
up to several decades, provided it does not become coated
or blocked with precipitates. Periodic maintenance may be
required to agitate the influent (upgradient) side of the iron
to loosen precipitates, which tend to concentrate in the first
few inches of reactive iron. It is also possible that the iron
may need to be periodically replaced, if maintenance
techniques can not successfully loosen precipitate buildup.
The timeframe for maintenance or replacement will vary
depending on flow rate, groundwater chemistry, and other
factors (Focht, Vogan, and O'Hannesin 1996)
This cost analysis assumes that the reactive iron will not
require replacement, but will require maintenance every 7
years to maintain flow through the system, or twice during
the 20-year project. According to ETI, this may be
accomplished using augers or in-situ soil mixing
equipment to agitate the influent face of the reactive iron
and loosen precipitates. However, this technique has not
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been attempted in a field setting, and therefore its
feasibility and effectiveness are currently undemonstrated.
For this reason, actual costs to perform iron maintenance
are unknown.
Based on mobilization and operating costs typically
associated with highly-specialized heavy equipment, for
each maintenance event labor, equipment mobilization,
decontamination, and operating costs for iron maintenance
are assumed to be equal to about 30 percent of the original
iron costs, or $40,500, for the continuous wall. Costs are
assumed to be slightly less, equal to about 20 percent of the
original iron costs, or $27,000, for the runnel and gate
system due to the shorter total length of the reactive iron
gates (Focht, Vogan, and O'Hannesin 1996; Means 1996).
Assuming that iron maintenance will be required twice
during the remediation project, estimated annual iron
restoration costs prorate to about $4,100 for the continuous
wall and $2,700 for the funnel and gate system, but could
vary significantly from these estimates, particularly if
portions of the iron need to be replaced. Also, if it is
necessary to remove monitoring wells to provide clear
access to the upgradient side of the iron, additional well
replacement costs may be incurred.
4.3.12 Site Demobilization Costs
Site demobilization includes removal of the reactive iron;
site cleanup and restoration; and off-site transportation and
disposal of the spent iron. Excavation and removal of the
iron could be accomplished with a conventional backhoe.
This estimate assumes that the iron is non-hazardous and
will bear a recycling credit of 3-5 percent of its original
value (about $4,000 to $7,000). Based on these
assumptions, no net costs for removal of the iron are
incurred. Backfill of the trench would be completed using
a backhoe and clean fill, at a cost of about $10 per cubic
yard. The nine monitoring wells would be removed and
the boreholes grouted to the ground surface at a cost of $20
per foot, for a total cost of about $3,000. Based on these
assumptions, net total iron removal and trench backfill
costs are assumed to be about $5,000 after the iron
recycling credit.
For the three-gate funnel and gate system, the iron would
be removed and recycled, and the sheet piling would also
be removed and hauled away as scrap, assuming it is non-
hazardous. The monitoring wells would be removed and
disposed of as non-hazardous demolition debris. The gate
areas would be brought to grade with clean fill. Net total
costs for removal of the system and backfill for the funnel
and gate system are assumed to be the same as for the
continuous wall, after recycling credits for the iron and
sheet piling ($5,000).
Final site restoration costs may include optional regrading
and seeding of the area. These costs are highly site-
specific; in this case, costs are assumed to be $6,000.
Total demobilization and site restoration costs are
assumed to be $11,000 for the continuous wall or for the
funnel and gate system. If the iron or sheet piling require
management as a hazardous waste, or do not bear the
assumed recycling value, demobilization costs could be
significantly higher.
4.4 Economic Analysis Summary
This analysis presents cost estimates for treating
groundwater contaminated with TCE, cDCE and VC.
Two options are discussed; a continuous reactive wall, and
a three-gate funnel and gate system. Operating
assumptions include treating a minimum saturated
thickness of 10 feet of groundwater flowing at a rate of
6.75 foot per day through a continuous wall, or 3.75 feet
per day for a funnel and gate system. Table 4-1 shows the
estimated costs associated with the 12 cost categories
presented in this analysis for the continuous wall. Table 4-
2 shows the estimated costs for the funnel and gate system.
Costs were not adjusted for inflation.
For the continuous wall, total fixed costs are estimated to
be about $466,600. Site preparation costs comprise about
57.6 percent of the total fixed costs; capital equipment
accounts for about 30.6 percent of the fixed costs. Figure
4-1 shows the distribution of fixed costs for the continuous
wall. Total annual variable costs are estimated to be about
$20,900. Analytical services (excluding sampling labor)
comprise about 44.5 percent of the variable costs; labor
(sampling and ordinary O&M) costs account for about
26.3 percent of these costs. The variable costs also include
estimated costs for iron maintenance activities assumed to
be required twice during the 20-year project; distributed
over the 20-year timeframe these costs account for about
19.6 percent of the annual variable costs. Figure 4-2 shows
the distribution of annual variable costs for the continuous
wall.
After operating for 20 years, the total fixed and variable
costs for the continuous wall remediation scenario
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presented in this analysis are estimated to $884,600. A
minimum of about 49.1 million gallons of groundwater
would be treated over this time period, assuming flow
velocities remain constant at 0.75 foot per day, and the
porosity and hydraulic conductivity of the entire wall
remain unchanged. Based on these criteria, the total cost
per 1,000 gallons treated is about $ 18.02, or about 1.8 cents
per gallon.
Figures 4-3 and 4-4 exhibit breakdowns of the estimated
fixed and variable costs associated with the funnel and gate
system, respectively. As shown on Figure 4-3, the major
differences between the costs for the continuous wall and
the funnel and gate system are in the site preparation
portion of the fixed costs. Although fixed costs for the
funnel and gate system are considerably higher, higher
maintenance costs are assumed to be required for the
continuous wall due to the greater length of iron wall that
will require maintenance. For this reason, the estimated
cost per gallon of groundwater treated for the funnel and
gate system (about 2 cents) is only slightly higher than for
the continuous wall. The volume of groundwater treated is
assumed to be the same in both cases. However, the actual
amount of groundwater that would pass through the funnel
and gate system would depend on the degree to which the
system can accelerate the natural groundwater flow
velocity, and therefore may differ from the amount that
would pass through a continuous wall. For this reason, and
other reasons previously discussed, actual costs may vary
significantly from estimates presented in this report.
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$11,000 (2.4%) Demobilization
$143,000 (30.6%) Capital Equipment
$4,000 (0.9%) Permitting
$40,000 (8.6%) Mobilization and Startup
$268,600 (57.6%) Site Preparation
Total Fixed Costs are estimated to be $466,600.
Figure 4-1, Distribution of fixed costs for continuous wall.
$9,300 (44.5%) Analytical Services
$2,000 (9.6%) Supplies
$4,100 (19.6%) Equipment Maintenance
$5,500 (26.3%) Labor
Notes: 1) Total Annual Variable Costs are estimated to be $20,900.
2) Routine sampling and O&M labor; does not include iron restoration.
Figure 4-2. Distribution of annual variable costs for continuous wall.
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$11,000 (1.9%) Demobilization
$143,000 (25.0%) Capital Equipment
$4,000 (0.7%) Permitting
,500 (5.7%) Mobilization and Startup
$382,100 (66.7%) Site Preparation
Total Fixed Costs are estimated to be $570,600.
Figure 4-3. Distribution of fixed costs for funnel and gate system.
$9,300 (47.7%) Analytical Services
$2,700 (13.8%) Equipment Maintenance
$5,500 (28.2%) Labor
$2,000 (10.3%) Supplies
Notes: 1) Total Annual Variable Costs are estimated to be $19,500.
2) Routine sampling and O&M labor; does not include kon restoration.
Ffgure 4-4. Distribution of annual variable costs for funnel and gate system.
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Section 5
Technology Status and Implementation
ETI has completed several bench-scale studies, five pilot-
scale tests using aboveground reactors and in-situ reactive
walls, and six full-scale installations of in-situ systems.
Several other field tests of in-situ installations are planned
for the near future in Massachusetts and Hawaii. ETI is
completing cooperative research and development/
licensing arrangements with several U.S. and multinational
industrial firms.
The in-situ implementation of the technology involves
installing a permeable treatment wall of coarse-grained
iron medium across the groundwater plume. The iron
degrades chlorinated VOCs as they migrate through the
wall under naturally occurring groundwater flow
conditions. When the in-situ metal-enhanced dechlorination
technology is applied to treat a large plume of
contaminated groundwater, impermeable sheet piles or
slurry walls may be used to funnel contaminated
groundwater through smaller permeable treatment
sections, known as gates. Selection of the appropriate type
of system depends on site-specific factors.
The metal-enhanced dechlorination process also may be
employed aboveground. Aboveground treatment units are
designed to treat extracted groundwater. Aboveground
treatment units can be available as trailer-mounted
transportable units or permanent installations. The
configuration of the aboveground units may include a
single unit or several units connected in series or in
parallel.
The metal-enhanced dechlorination technology is
implemented through a four-phase approach. A site data
assessment is conducted during phase 1; a feasibility
evaluation involving bench-scale testing (and pilot-scale
testing if necessary) is conducted during phase 2; system
design, costing, and construction occurs during phase 3;
and phase 4 involves long-term performance monitoring.
Phases 1 and 2 may take about 2 to 4 months, and phase 3
may take about 6 months. The duration of phase 4 will
depend on site-specific conditions and regulatory
requirements. The phases are described in subsequent
sections.
Phase 1 - Site Data Assessment
The purpose of a site data assessment is to review existing
data to evaluate site conditions that may affect the
performance of the technology. On the basis of this
review, the site may be placed into one of two categories.
The first category includes sites with a physical setting and
groundwater chemistry similar to other sites at which the
metal-enhanced dechlorination technology has been
shown to be effective. Therefore, implementation of phase
2 (a feasibility evaluation) is not necessary before phase 3
activities begin.
The second category includes sites with unique physical
and geochemical properties that may affect the application
of the metal-enhanced dechlorination technology. The
probability for the successful application of the technology
at these sites is unknown, due to the presence of untested
chemicals, unusual inorganic chemistry, or unusual
geologic settings. For these sites, implementation of phase
2 activities is needed before phase 3 activities can begin.
Data that are necessary to assess a site include:
Groundwater inorganic and organic chemistry:
The inorganic chemistry of groundwater is impor-
tant because it indicates whether metals can pre-
cipitate during treatment. The effect of metal pre-
cipitation on the performance of the technology is
discussed in Section 3.1.1. The nature of organic
contaminants present in groundwater determines
the applicability of the technology to a particular
site, as discussed in Section 3.1.1.
73
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VOC characteristics: The technology is appro-
priate for treating chlorinated methanes, some
ethanes, and ethenes. Each compound and its po-
tential by-products have a half-life. The half-life
of each compound and its degradation by-prod-
ucts are critical parameters with regard to residence
time when designing a treatment system.
Site geology and soils: The type of materials,
depth to water, saturated thickness, and presence
of an underlying aquitard are important consider-
ations for the design and implementation of in-
situ installations of the metal-enhanced dechlori-
nation technology.
Hydrogeological data: Horizontal gradient, hy-
draulic conductivity and groundwater flow veloc-
ity will affect the performance of the metal-en-
hanced dechlorination technology because they
influence the residence time of groundwater in the
reactive wall, which affects the required wall thick-
ness.
Phase 2 - Feasibility Evaluation
If the site is placed into the second category as defined in
phase 1, a feasibility evaluation is typically performed.
The purpose of phase 2 is to evaluate the efficiency of the
metal-enhanced dechlorination technology under simulated
groundwater flow conditions, by performing laboratory
bench-scale (column) tests using representative
groundwater samples collected from the site. Groundwater
flow and geochemical models may be used to assist in the
feasibility evaluation. Feasibility testing should (1)
confirm that the VOCs present are degraded by the
process, (2) evaluate the rates of VOC degradation, and (3)
evaluate associated inorganic geochemical reactions.
Following successful laboratory bench-scale tests, a pilot-
scale field test may be conducted to collect additional data
to support full-scale application of the process; however,
according to ETI, pilot-scale testing is no longer typically
required. Pilot-scale testing may not be required, or may
be very limited for sites having contaminant, geochemical,
and hydrogeologic characteristics similar to other sites for
which ETI has extensive past performance data. However,
it is important to note that because the technology is
relatively new, state regulatory authorities may still
require a pilot-scale study if the technology has not been
shown to be effective in that particular state. If pilot-scale
testing is required, the'results of the bench-scale studies are
used to design the pilot-scale system. The pilot-scale
system may be in-situ or aboveground, depending on the
potential full-scale application and site conditions: This
field test provides data which are readily extrapolated to
estimate full-scale costs, long-term performance and
operation, and maintenance requirements.
A feasibility evaluation report is prepared to document
phase 2 testing results. The report interprets the laboratory
data with respect to the site's hydrogeologic characteristics
and provides information required for the preliminary
design and cost estimating activities performed in phase 3.
Phase 3 - System Design, Costing, and
Implementation
Phase 3 is the design, costing, and construction of a full-
scale system. The results from phase 2 provide the basis
for full-scale design. The half-lives of the chlorinated
VOCs present in the groundwater and the half-lives of
potential dechlorination by-products, determined through
bench-scale testing, and data collected during the pilot-
scale testing (if required), are used to confirm the correct
volume of iron required to treat the types and
concentrations of contaminants present. The full-scale
system dimensions are determined based on the total
residence time necessary for dechlorination; the flow
velocity, and the contaminant plume dimensions. These
criteria determine the thickness of the reactive iron wall in
an in-situ system. For in-situ systems, hydrogeologic
factors such as saturated thickness and plume dimensions
will also influence the full-scale system design.
Once the full-scale system design is finalized, the system is
constructed. According to ETI, steady state operating
conditions are typically achieved by the time about 20 to
30 pore volumes of groundwater has passed through the
system (ETI 1994).
Phase 4 - Long-Term Performance Monitoring
and Maintenance
Routine performance monitoring and reporting are
performed according to regulatory requirements.
Performance monitoring includes sampling and analysis
of treated groundwater to determine the concentrations of
VOCs of concern. Decreases in dissolved metal
concentrations indicate formation of insoluble precipitates
that may clog the reactive iron medium.
74
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As discussed in Section 3, periodic maintenance may be
required to restore the hydraulic conductivity and
reactivity of the iron. ETI estimates that for full-scale in-
situ systems, these activities may be required every 5 to 10
years.
75
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Section 6
References
Appleton, Elaine. 1996. "A Nickel-Iron Wall Against
Contaminated Groundwater." Environmental Science
and Technology News, Volume 30, Number 12.
Chen, Chien T. 1995. Excerpts from Presentation Titled
"Iron Reactive Wall." Innovative Site Remediation
Workshop, Sturbridge, Massachusetts. September 13-
14.
EnviroMetal Technologies, Inc. (ETI). 1994. Revised
Draft: Rationale for Suggested Design and Monitoring
Program, Pilot Scale Field Trial of the EnviroMetal Pro-
cess.
ETI. 1996a. Draft Evaluation Report; Pilot-Scale Funnel
and Gate, New York. Prepared for Steams andWheler
L.L.C.(S&W). March.
ETI. 1996b. Draft Correspondence Regarding Ground-
water Flow Velocity Measurements. From John Vogan,
Manager, to Diane Clark, Senior Engineer, S&W. Oc-
tober 24.
ETI.1996c. Case Studies of Various Applications of the
Metal-Enhanced Dechlorination Process. November 5.
ETI. 1996d. Memorandum Regarding Potential Full-Scale
Costs of In-Situ Treatment. From John Vogan, Man-
ager, to Diane Clark, Senior Engineer, S&W. Novem-
ber 25.
ETI. 1997. Correspondence Regarding Draft Innovative
Technology Evaluation Report (ITER) for the New York
Demonstration of the In-Situ Application of the Metal-
Enhanced Dechlorination Process. Form Robert Focht,
Hydrogeologist, to Guy D. Montfort, PRC Environmen-
tal Management, Inc. (PRC). April 2.
Evans, G. 1990. "Estimating Innovative Treatment Tech-
nology Costs for the SITE Program." Journal of Air
and Waste Management Association. Volume 40, Num-
ber?. July.
Focht, R., Vogan, J., and O'Hannesin, S. 1996. "Field
Application of Reactive Iron Walls for In-Situ Degra-
dation of VOCs in Groundwater." Remediation. Vol-
ume 6, Number 3. Pages 81-94.
Gillham, Robert W, and Stephanie F. O'Hannesin. 1994.
"Enhanced Degradation of Halogenated Aliphatics by
Zero-Valent Iron." Ground Water. Volume 32, Num-
ber 6.
Gillham, Robert W. 1995. "Resurgence in Research Con-
cerning Organic Transformations Enhanced by Zero-
Valent Metals and Potential Application in Remediation
of Contaminated Groundwater. Preprint extended ab-
stract presented before the American Chemical Society,
Anaheim, California. April 2-7. Pages 691-694.
Gillham, Robert W. 1996. "In-Situ Treatment of Ground-
water: Metal-Enhanced Degradation of Chlorinated
Organic Contaminants." Recent Advances in Ground-
water Pollution Control and Remediation. M.M. Aral
(ed.), Kluwer Academic Publishers. Pages 249-274.
O'Hannesin, Stephanie F., and Robert W. Gillham. 1992.
"A Permeable Reaction Wall for In-Situ Degradation of
Halogenated Organic Compounds." Paper Presented at
the 1992, 45th Canadian Geotechnical Society Confer-
ence. Toronto, Ontario, Canada. October.
O'Hannesin, Stephanie F., 1993. "AField Demonstration
of a Permeable Reaction Wall for In-Situ Abiotic Deg-
radation of Halogenated Organic Compounds." (M.Sc.
Thesis, University of Waterloo.)
Means, R.S. Company, Inc. (Means). 1996. Environmen-
tal Restoration Assemblies Cost Book. R.S. Means
76
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Company, Inc., Kingston, Massachusetts.
PRC Environmental Management, Inc. (PRC). 1995.
EnviroMetal Technologies, Inc. "Metal Enhanced Abi-
otic Degradation Technology SITE Program Demon-
stration Final Quality Assurance Project Plan." Sub-
mitted to EPA ORD, Cincinnati, Ohio. May.
PRC. 1996. Record of Telephone Conversation Regard-
ing Inorganic Data from New York
Demonstration. Between Guy D. Montfort, Project Man-
ager, and John Vogan, ETI. December.
PRC. 1997. Record of Telephone Conversation Regard-
ing Full-Scale Funnel and Gate Design. Between Guy
D. Montfort, Project Manager, and Rob Focht, ETI.
January.
Puls, R., Powell, R., and Paul, C. 1995. "In-Situ
Remediation of Ground Water Contaminated with Chro*-
mate and Chlorinated Solvents Using Zero-Valent Iron:
a Field Study. Presented Before the Division of Envi-
ronmental Chemistry. American Chemical Society.
Anaheim, California. April 2-7. Pages 788-791.
Reardon, Eric. 1995. "Anaerobic Corrosion of Granular
Iron: Measurement and Interpretation of Hydrogen Evo-
lution Rates." Environmental Science & Technology,
Volume 29, No. 12. Pages 2936-2945.
Snoeyink, Vernon L. and David Jenkins. 1980. Water
Chemistry. John Wiley & Sons. New York.
Stearns and Wheler, Inc. (S&W). 1993. Final Remedial
Investigation Report (for the New York Demonstration
Site). January.
S&W. 1994. Draft Work Plan for the Field Trial of the
EnviroMetal Process. October.
U.S. Department of Energy (DOE). 1988. Radioactive
Waste Management Order. DOE Order 5820.2A. Sep-
tember.
EPA. 1987. Joint EPA-Nuclear Regulatory Agency Guid-
ance on Mixed Low-Level Radioactive and Hazardous
Waste. Office of Solid Waste and Emergency Response
(OSWER) Directives 9480.00-14 (June 29), 9432.00-2
(January 8), and 9487.00-8. August.
EPA. 1988a. Protocol for a Chemical Treatment Demon-
stration Plan. Hazardous Waste Engineering Research
Laboratory. Cincinnati, Ohio. April.
EPA. 1988b. CERCLA Compliance with Other Environ-
mental Laws: Interim Final. OSWER. EPA/540/G-89/
006. August.
EPA. 1988c. Guidance for Conducting Remedial Investi-
gations and Feasibility Studies Under
CERCLA. OSWER. EPA/540/G-89-004. October.
EPA. 1989. CERCLA Compliance with Other Laws
Manual: Part II. Clean Air Act and Other Environmen-
tal Statutes and State Requirements. OSWER. EPA/
540/G-89-006. August.
EPA. 1997. Metal-Enhanced Dechlorination of VOCs
Using an Aboveground Reactor. SITE Program Inno-
vative Technology Evaluation Report EPA /540/R-96/
503. Office of Research and Development - National
Risk Management Research Laboratory. July.
Yamane, C.L., S. Warner, J. Gallinatti, F. Szerdy and T.
Delfino. 1995. Installation of a Subsurface Ground-
water Treatment Wall Composed of Granular Zero-Va-
lent Iron. Preprint Extended Abstract Presented before
the Division of Environmental Chemistry. ACS. Ana-
heim, California. April 2-7. Pages 792-795.
77
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Appendix A
Vendor's Claims for the Technology
The metal-enhanced dechlorination technology uses a
metal (usually iron) to enhance the abiotic degradation of
dissolved halogenated organic compounds. Laboratory-
scale and field-scale pilot studies conducted over the past
5 years at the Waterloo Centre for Groundwater Research,
University of Waterloo, and at several commercial sites in
the U.S., have shown that the process can be used
effectively to degrade halogenated methanes, some
ethanes, and ethenes over a wide range of concentrations.
These studies have shown that:
ป The degradation kinetics appear to be pseudo first-
order (i.e., die rate of reaction is directly propor-
tional to the concentration of the reactants)
With few exceptions, no persistent products of
degradation have been detected and degradation
appears to be complete given sufficient tune
The degradation rates of chlorinated compounds
are several orders of magnitude higher than those
observed under natural conditions
The reaction rate is dependent on the surface area
of iron available
A.1 Advantages and Innovative
Features
Reactants are relatively inexpensive
* The treatment is passive and requires no external
energy source
Contaminants are degraded to harmless products,
rather than being transferred to another medium
requiring subsequent treatment, regeneration, or
disposal
The reactive iron is highly persistent with, depend-
ing upon the application, the potential to last for
several years to decades without having to be re-
placed
The process is one of the few that appears to have
potential for passive in-situ treatment
The process degrades a wide range of chlorinated
volatile organic compounds, including
trichloroethene, tetrachloroethene, cis-1,2-
dichloroethene, and vinyl chloride. Preliminary
tests suggest that it may be applicable for a wider
range of compounds in addition to chlorinated "ali-
phatic" hydrocarbons.
A.2 Technology Status
The first full-scale in-situ installation of the,technology
occurred at an industrial facility in California in December
1994. Eleven installations of either pilot or full-scale
systems have been completed to date. These in-situ
installations and others planned in 1997 will assist in the
assessment of the long-term field performance of the
technology.
The results collected to date show that the ETI technology
could be a highly effective aboveground or in-situ method
of remediating waters containing chlorinated aliphatic
compounds. An in-situ permeable treatment wall of
coarse-grained reactive media installed across the plume
will degrade compounds as they migrate through the zone
under naturally occurring groundwater flow conditions.
By utilizing impermeable sheet piles or slurry walls, a
large plume of contaminated groundwater can be funneled
through smaller permeable treatment sections.
78
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Appendix B
Case Studies
This appendix summarizes several case studies on the use
of metal^enhanced dechlorination technology. These case
studies involve bench-scale units, pilot-scale units, and
full-scale units treating contaminated groundwater. The
information available for these case studies ranged from
detailed analytical data to limited information on system
performance and cost. Results from five case studies are
summarized in this appendix.
B.1 Semiconductor Facility, South San
Francisco Bay, California
B.1.1 Project Description
Several studies were performed by EnviroMetal
Technologies, Inc. (ETI), using groundwater from a
former semiconductor manufacturing site in South San
Francisco Bay, California to examine the feasibility of
constructing and operating an in-situ permeable wall
containing a reactive iron medium to replace an existing
pump-and-treat system. Groundwater at this site was
contaminated with trichloroethene (TCE), cis-1,2-
dichloroethene (cDCE), vinyl chloride (VC), and Freon
113. Results of laboratory column studies performed by
ETI indicated that the concentration of dissolved volatile
organic compounds (VOCs) in the groundwater was
significantly reduced. Following the laboratory studies,
pilot- and full-scale units were installed.
B.1.2 Results
Pilot-Scale System
An aboveground demonstration reactor, containing 50
percent iron by weight and 50 percent sand by weight was
installed and operated over a 9-month period. Groundwater
was pumped through the demonstration reactor at a flow
velocity of 4 feet per day.
The groundwater at the semiconductor facility site was
highly mineralized. Although precipitate formation was
evident at the influent end of the test reactor, the rate of
degradation remained relatively constant over the 9-
month test period. The following were the pilot-scale test
results:
TCE, 210 ppb, 1.7-hour half-life
cDCE, 1,415 ppb, 0.9-hour half-life
VC, 540 ppb, 4.0-hour half-life
Several other aspects of the metal-enhanced dechlorination
process were evaluated during this pilot-scale test,
including the following.
Metals precipitation - Inorganic gebchemical data
collected in the field was used to predict the po-
tential for precipitate formation in the reactive iron
material. Operation and maintenance requirements
for the full-scale design were based on the evalu-
ation of the metals precipitation data.
Hydrogen gas production - Hydrogen gas may
be produced as a consequence of the dissociation
of water in the presence of granular iron. Rates of
hydrogen gas generation measured in the labora-
tory (Reardon 1995) were used to evaluate the need
for any hydrogen gas collection system in the full-
scale application. Based on the evaluation, no need
for a hydrogen gas collection system was indicated.
Microbial Effects - Groundwater from within the
reactor was sampled for microbial analysis. The
results indicated that the microbial population in
the reactor was similar to the population observed
in untreated groundwater. There was no visual
evidence of biomass generation during the test.
79
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Full-Scale System
Based on the pilot-test results, a full-scale in-situ treatment
wall was installed in December 1994. The reactive wall
was 4 feet thick, 40 feet long, and situated vertically
between depths of about 7 feet and 20 feet below ground
surface. The 4-foot-thick zone of 100 percent granular
iron was installed to achieve a hydraulic residence time of
about 4 days to treat VOCs to cleanup standards, based on
the estimated groundwater velocity of 1 foot per day. VC
required the longest residence time to degrade to cleanup
standards. A layer of pea gravel about 1 foot thick was
installed on both the upstream and downstream sides of the
reactive wall. The reactive wall was flanked by slurry
walls to direct groundwater flow towards the reactive iron
medium. The construction cost for the reactive wall was
about $225,000. Together with slurry walls, capital costs
were about $720,000.
At the time tin's report was prepared, minimal data for the
full-scale system were available. Monitoring wells were
installed near the upstream and downstream faces. Initial
results indicate that chlorinated VOCs are being reduced
to below regulatory levels. For further details see Yamane
etal 1995 and Szerdy and others 1995.
Sources: Yamane and others 1995; Szerdy and others
1995; ETI1996; Focht, Vogan, and O'Hannesin 1996.
B.2 Canadian Forces Base, Borden,
Ontario, Canada
B.2.1 Project Description
In May 1991, a small-scale in-situ field test was initiated at
the Borden site to treat groundwater contaminated with
TCE and PCE. The source of the contaminant plume at the
site was located about 4 meters (m) below ground surface
and 1 m below the water table. The plume was about 6.6
feet wide and 3.3 feet thick, with a maximum
concentration along the axis of about 250,000 and 43,000
ug/L for TCE and PCE, respectively. An in-situ
permeable wall was constructed about 18 feet downgradient
from the source. The aquifer material consisted of a
medium to fine sand, and the average groundwater
velocity was about 0.3 feet per day.
The reactive wall was constructed by driving sheet piling
to form a temporary cell 5.2 feet thick and 18 feet long.
The native sand was replaced by the reactive iron medium,
consisting of 22 percent iron grindings by weight and 78
percent coarse sand by weight. After the reactive iron
medium was installed, the sheet piling was removed,
allowing the contaminant plume to pass through the wall.
Rows of multilevel samplers were located 1.6 feet
upgradient from the wall, at distances of 1.6 feet and 3.3
feet into the wall, and 1.6 feet downgradient from the wall,
providing a total of 348 sampling points.
B.2.2 Results
Samples were collected and analyzed over a five-year
monitoring period. There was no apparent change in
performance and no maintenance required over the five-
year duration of the test. The results indicated that about
90 percent of the TCE and 86 percent of the PCE was
removed as the contaminant plume passed through the
wall. Amounts of dechlorination by-products (tDCE and
cDCE) equivalent to about 2 percent of the original mass
of TCE and PCE present in the influent were detected at
sampling points within the wall. However, these
byproducts also were dechlorinated with further distance
through the wall. An observed increase in chloride
concentrations in effluent samples indicated that the
decline in TCE and PCE concentrations was a
consequence of dechlorination processes. Although the
effluent did not achieve drinking water standards, based on
current knowledge it appears that use of a greater
proportion of iron relative to contaminant loading, or use
of a more reactive form of iron, could have improved
performance. No VC was detected as a result of PCE,
TCE, or cDCE degradation, and no bacterial growth was
observed. Examination of the iron medium by X-ray
diffraction and scanning electron microscopy did not
indicate the presence of precipitate on the reactive
material.
Source: Gillham 1996.
B.3 Industrial Facility, Kansas
B.3.1 Project Description
A groundwater investigation during the early 1990s
identified a TCE plume, with concentrations ranging from
100 to 400 ppb (ug/L), egressing from an industrial facility
in Kansas. The TCE occurs in a basal alluvial sand and
gravel zone overlying the local bedrock, at a depth of
about 30 feet below ground surface. In mid-1995, a
80
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treatability study was conducted on groundwater from the
facility to determine the effectiveness of granular iron in
degrading chlorinated organic compounds in the
groundwater.
The treatability study consisted of pumping groundwater
from the site through a laboratory column containing the
iron material. The column test provided site-specific
information on (1) the dechlorination rate of TCE; (2) the
potential for the formation and degradation of chlorinated
by-products; and (3) potential inorganic chemical
changes. The results of this study were used to determine
the required residence time necessary for the dechlorination
of TCE and its degradation products.
A groundwater model of the site was then generated,
incorporating various funnel and gate configurations.
This model helped to determine the size of the in-situ
system necessary to capture and treat the plume of
contaminated groundwater, and to estimate the expected
groundwater velocity through the gate. The velocity
estimate, together with the required residence time
determined from the treatability study, were used to
determine the necessary thickness of the iron section in the
gate.
During December 1995 through January 1996 a 1,000-
foot-long funnel and gate system was installed at the
facility property boundary. A low natural groundwater
velocity permitted the use of a high funnel-to-gate ratio;
the velocity increase due to the tunneling action permitted
a reasonably small treatment zone to be built. The system
was constructed with about 490 feet of impermeable
funnel on either side of a 20-foot long reactive gate.
Construction of the funnel sections was accomplished by
first constructing a single, soil-bentonite slurry wall. After
the wall had set, the 20-foot gate section was excavated in
the middle of the wall. The iron zone was tปien installed in
the gate section, measuring about 13 feet deep and about 3-
feet wide (that is, the flow-through thickness was 3 feet).
Weather delays and other non-technical delays extended
the construction period; however, the construction
contractor estimated that under optimal conditions the
slurry wall could have been built in two weeks, and the
reactive gate section in one week.
B.3.2 Results
Costs for the installation (slurry walls and gate) were about
$400,000, including 70-tons of granular, reactive iron.
Results to date show nondetectable concentrations of
VOCs in the wells screened in the gate. For further details
see Focht, Vogan, and O'Hannesin 1996.
Sources: ETI1996; Focht, Vogan, and O'Hannesin 1996.
B.4 U.S. Coast Guard Facility, North
Carolina
In June 1996, an in-situ reactive wall was installed near a
former machine shop at a U.S. Coast Guard facility in
Elizabeth City, North Carolina, using a continuous
trenching technique, to treat a groundwater contaminant
plume with TCE concentrations of about 10 mg^L and
hexavalent chromium also at about 10 mg/L. The reactive
wall measures about 150 feet in length, 2 feet in width, and
extends to about 26 feet bgs.
For excavation, continuous trenching was performed with
a cutting chain excavating system, similar to a Ditch
Witch. As the chain excavator moved across the
designated trench boundary, soils were brought to the
surface and deposited onto the ground surface. The soils
were eventually analyzed for hazardous constituents and
removed from the site. A steel trench box, extending to the
width and depth of the trench, was pulled immediately
behind the chain excavator and served to keep the trench
open and allow the emplacement of granular iron into the
trench. Through a hopper above the trench box, granular
iron was fed into and through the trench box to the
excavated area. This process, which involved the
placement of about 450 tons of iron, was continued for the
entire length of the trench and was completed in a single
day. Total cost of the installation was about $500,000 with
the iron costing just under $400 per ton.
Source: Blowes and others 1997; ETI 1996
B.5 Lakewood Colorado Facility
The largest in-situ funnel and multiple gate system to date
was installed from July through November 1996 at a
government facility in Lakewood, Colorado. The facility
is underlain by unconsolidated sediment and bedrock
aquifers, with the bedrock surface at about 25 feet bgs.
Groundwater contamination at the facility, mainly VOCs,
is present in both aquifers at varying concentrations (TCE
and DCE: 700 ug/L maximum; vinyl chloride: 15 ug/L
maximum), and over a widespread area.
81
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A sheet piling wall, which serves as the funnel for this
system, was installed over a length of 1,040 feet and to a
depth of 25 feet bgs. Four 40-foot long reactive gate
sections with varying thicknesses were installed at
designated locations along the wall. Varying gate section
thicknesses were used to compensate for variations in
groundwater flow velocities and VOC concentrations in
different parts of the site. In accomplishing the funnel
installations, sheet piling boxes were erected at each
location and native material was excavated from inside
each box. A thin layer of pea gravel was then placed at the
bottom of each excavation followed by granular iron up to
about 9 to 13 feet bgs.
Groundwater flow velocities are expected to range from
less than 1 foot per day (ft/day) to about 10 ft per day; data
collection is currently underway to determine these. Initial
monitoring data indicate that effluent contaminant
concentrations are meeting the design criteria.
Source: ETI1996.
B.6 References
Blowcs, D.W., R.W. Puls, T.A. Bennett, R.W. Gillham, C. J.
Hanton-Fong, and CJ. Ptacek. 1997. "In-Situ Porous
Reactive Wall for Treatment of Cr(VI) and Trichloroet-
hylene in Groundwater." 1997 International Contain-
ment Technology Conference and Exhibition, St. Pe-
tersburg, Florida. February 9-12.
EnviroMetal Technologies, Inc. (ETI). 1996-Case Studies
for Various Applications of the Metal-Enhanced Dechlo-
rination Process. November 5.
Focht, R. J. Vogan, and S. O'Hannesin. 1996. "Field
Application of Reactive Iron Walls for In-Situ Degra-
dation of Volatile Organic Compounds in Groundwa-
ter". Published in "Remediation;" Volume 6, No. 3.
Pages 81-94.
Gillham, R. W. 1996. "In-Situ Treatment of Groundwa-
ter: Metal-Enhanced Degradation of Chlorinated Or-
ganic Contaminants." Recent Advances in Groundwa-
ter Pollution Control and Remediation. M. M. Aral
(ed.), Kluwer Academic Publishers. Pages 249-274.
O'Hannesin, Stephanie F., 1993. "A Field Demonstration
of a Permeable Reaction Wall for In-Situ Abiotic
Degradation of Halogenated Organic Compounds."
(M.Sc. Thesis, University of Waterloo.)
Szerdy, F.S., J.D. Gallinatti, S. D. Warner, C. L. Yamane,
D.A. Hankins, and J. L. Vogan. 1995." In-Situ
Groundwater Treatment by Granular Zero-Valent Iron -
Design, Construction and Operation of an In-Situ Treat-
ment Wall." Published by Geomatrix Consultants, Inc.
San Francisco, California.
Yamane, C.L., et. all995. "Installation of a Subsurface
Groundwater Treatment Wall Composed of Granu-
lar Zero-Valent Iron." Preprint Extended Abstract Pre-
sented before the Division of Environmental Chemis-
try. ACS. Anaheim, California. April 2-7. Pages 792 -
795.
82
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Appendix C
Analytical Data Tables
83
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Tabl'8 C-1. Summary of Analytical Data-June
SAMPLE
Dili
SUBSTANCE DETECTED
VOCs (mlcrognmtMif);
Acetone
Chloroform
1.1-DfcMoroethane
cls-1.2-dtchloroethene
trans-1,2-d!cWoroetherte
Telrachloroethene
1,1.1-Trichloroethiuio
Trichloroethene
Vinyl chloride
Tentatively Identified Compounds (total)
Mttals (milligrams/liter):
Aluminum
Barium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Potassium
Sodium
Zinc
Wet Chemistry (milligrams/liter}:
Bicarbonate Alkalinity
Chloride
Nitrate/Nitrite Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
SuHate
Total Phospholipld Fatty Acid*:
(Average; pfcomoles/liter)*
MW-U1
06/07/95
5.00
1.00
1.5
160
1.00
1.00
4.6
130
7.1
3J
Z96
0.0227
71.3
0.010
0.020
4.49
0.0050
11.2
0.415
2.05
29.2
R.021B
167
48
0.529
0.47
0.0591
19
22,188
HW-U2
5.00
1.00
1.9
220
1.00
1.00
6.5
170
8.3
3J
1.5
0.020
66.7
0.010
0.020
2.42
0.0050
10.0
0.241
1.59
27.4
0.0146
162
49
0.57
0.525
0.0451
20.8
14,865
MW-U3
06/07/35
5.00
1.00
1.1
120
1.00
1.00
3.2
74
4.9
2J
3.32
0.020
93
0.010
0.020
6.34
0.050
14.9
0.393
2.68
38.7
0.0277
139
48.4
0.332
0.307
0.0251
19.1
45,310
HW-FE1
06/07/3S
5.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
3J
0.10
0.535
12.8
0.0155
0.0422
16.6
0.0050
5.7
0.245
1.54
35.4
0.010
17.2
53.8
0.0591
0.0591
0.010
18.8
34,166
MW-FE2
OS/08/S5
12
1.00
1.00
1.6
1.00
1.00
1.00
1.00
1.00
3J
2.37
0.521
18.6
0.0172
0.0361
27.8
0.0050
4.02
0.56
2.26
36.1
0.0205
18.5
53.7
0.0609
0.0501
0.0108
21.2
29.550
WW-FE3
OS/07/SS
13
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
13J
0.10
0.723
12.9
0.010
0.020
5.47
0.0050
7.31
0.182
1.53
35.2
0.010
34.1
53
0.0579
0.0579
0.010
18.1
21,065
HW-D1
06/07/35
13
1.00
1.00
24
1.00
1.00
1.00
5.7
1.3
U
0.561
0.020
18.9
0.010
0.020
0.823
0.0050
2.82
0.202
1.09
32.8
0.010
41.4
52.2
0.050
0.050
0.0197
18.1
43,233
MW-D2
OS/OI/9S
12
1.00
1.00
38
1.00
1.00
1.00
7.3
2.1
3J
1.02
0.020
20.5
0.010
0.020
1.12
0.0050
3.13
0.142
1.00
29
0.0104
42.4
47.8
0.050
0.050
0.0133
18.7
13.781
MW-D3
M/07/SE
9.S
1.00
1.00
30
1.00
1.00
1.00
6.8
1.6
0
1.14
0.020
17.8
0.010
0.020
1.42
0.0296
2.69
0.186
1.22
29.3
0.0229
40.4
45.7
0.050
0.050
0.010
18.8
17.084 .
MW-D4
OE/07/35
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
7.08
0.142
126
0.0113
0.020
10.9
0.00947
34.9
1.21
2.77
27.6
0.0525
NA
NA
NA
NA
NA
NA
1.985
MW-OS
&M8/3S
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.313
0.04
55.5
0.010
0.020
0.794
0.0050
7.38
0.512
1.25
25.1
0.0206
NA
NA
NA
NA
NA
NA
1.908
MW-DS
06/07/36
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
1.25
0.0934
66.8
0.01 U
0.020
2.08
0.0050
12.8
1.02
1.68
28.2
0.0118
NA
NA
NA
NA
NA
NA
1.942
Notes:
U > substance not detected; associated value is the reported detection limit
NA = parameter not analyzed
* Average value of replicate samples
I = estimated concentration
-------
Table C-2. Summary of Analytical Data-July
SAMPLE
SUBSTANCE DETECTED
VOCs (mlcrogramsfflter):
Chloroform
1,1-Dichloroethane
cis-1 ,2-Dichloroelhene
trans-1 ,2-Dichloroemene
Tetrachloroethene
1 , 1 , 1 -Trichloroethane
Trichloroethene
Vinyl chloride
Tentatively Identified Compounds (Total)
Metals (milligrams/liter):
Barium
Calcium
Chromium
Iron
Lead
Magnesium
Manganese
Potassium
Sodium
Zinc
Wet Chemistry (milligrams/liter):
Bicarbonate Alkalinity
Chloride
Nitrate/Nitrite Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
Sulfate
Total Phospholipld Fatty Acids:
(Average; picomoles/liter)*
MW-U1
07/13/95
5.0U
l.OU
3.5
230
1.2
l.OU
l.OU
100
23
3J
0.10U
0.0374
90.8
0.01U
0.02U
0.0784
0.05U
12.6
0.559
l.OU
31.8
0.0198
288
52.8
0.338
0.338
0.01U
16.7
NA
MW-U2
07/12/95
5.0U
l.OU
2.8 -
280
l.OU
l.OU
4.5
160
16
91
0.10U
0.0268
88.8
0.01U
0.02U
0.05U
0.05U
12.3
0.427
l.OU
31
0.0253
278
53.2
0.378
0.05U
0.378
17.1
NA
MW-U3
07/11/95
5.0U
l.OU
3.1
360
1.0
10U
l.OU
280
18
2J
0.155
0.02U
88
0.01U
0.02U
0.184
0.05U
12.5
0.281
l.OU
31.4
0.0268
290
53.2
0.383
0.383
0.01U
16.7
NA
MW-FE1
07/13/95
12
l.OU
l.OU
l.OU
l.OU
1.0U
l.OU
l.OU
l.OU
1U
0.10U
0.241
14.5
0.01U
0.02U
0.41
0.05U
10.8
0.24
1.65
30
0.01U
59.4
52.1
0.05U
0.05U
0.01U
15.6
NA
MW-FE2
07/12/95
5.0U
l.OU
l.OU
l.OU
l.OU
l.OU
t.OU
l.OU
l.OU
61
0.10U
0.522
14.3
0.01U
0.02U
0.252
0.05U
10.2
0.111
1.45
30.9
0.0109
55.6
54
0.05U
0.05U
0.01U
16.1
NA
MW-FE3
07/11/95
9.6
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
1.2
U
0.1U
0.161
15
0.01U
0.02U
0.615
0.05U
11.3
0.312
1.66
30.8
0.0113
63
53.3
0.05U
0.05U
0.01U
14.9
NA
MW-D1
07/13/95
8.4
l.OU
l.OU
2.2
l.OU
l.OU
l.OU
l.OU
l.OU
1U
0.10U
0.0739
22.6
0.01U
0.02U
0.0883
0.05U
7.06
0.243
1.42
30.2
0.0129
84.8
51.8
0.05U
0.05U
0.01U
11.8
NA
MW-D2
07/12/95
24
l.OU
l.OU
3.7
l.OU
l.OU
l.OU
t.OU
l.OU
81
0.17
0.02U
13.7
0.01U
0.02U
0.05U
0.05U
2.87
0.127
l.OU
27.5
0.0115
51.5
48.6
0.05U
0.05U
0.01U
5.7
NA
MW-D3
07/11/95
30
l.OU
1.0U
3.9
l.OU
l.OU
l.OU
l.OU
l.OU
1U
0.107
0.0494
17.6
0.01U
0.02U
0.0571
0.05U
6.18
0.222
1.36
28.8
0.0124
48
51.4
0.05U
0.05U
0.01U
14.2
NA
MVV-D4
07/13/95
5.0U
1.00
l.OU
30
l.OU
l.OU
l.OU
29
l.OU
1U
0.153
0.02U
21.3
0.01U
0.02U
0.174
0.05U
2.96
0.156
1.0U
27.9
0.01U
NA
NA
NA
NA
NA
NA
NA
MVY-DS
07/12/95
44
l.OU
l.OU
50
l.OU
l.OU
l.OU
54
2.2
21
0.10U
0.0246
36
0.01U
0.02U
0.05U
0.05U
4.91
0.312
l.OU
26.7
0.0161
NA
NA
NA
NA
NA
NA
NA
MW-D6
07/11/95
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.11
0.035
30.2
0.01U
0.02U
0.104
0.05U
4.74
0.516
l.OU
28.2
0.0144
NA
NA
NA
NA
NA
NA :
NA
Notes:
U-substance not detected; associated value is detection limit. * Average value of replicate samples
NA = parameter not analyzed. J = estimated concentration.
VOC sample fractions were collected from wells MW-D4 and D5 for lie sole purpose of supporting the demonstration health and safety program, and were not required by the project quality assurance project plan;
VOC data from these wells are not directly relevant to demonstration objectives.
-------
Tab!ฎ C-3. Summary of Analytical Data-August
SAMPLE
Dtte
SUBSTANCE DETECTED
VOCi (uicroinms/lller):
Acetone
Chloroform
1,1-DkhIotoerhane
ct!-l,2-DichIoroethene
trans-1 ,2-Dichloroethene
Tetrachloroethene
1,1,1-Trichloroethane
Trichloroethene
Vinyl chloride
Tentatively Identified Compounds (Total)
MeUls (milligrams/liter):
Ahiminum
Barium
Calcium
OO ;.! -
O\ Chromium
Copper
Iron
Lead
Magnesium
Manganese
Potassium
Sodium
Zinc
Wet Chemistry (milligrams/liter):
' Bicarbonate Alkalinity
Chloride
Nitrate/Nitrite Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
Sulfate
Total Phospholipid Fatty Acids:
(Averager picomoles/liter)*
MW-W
08/01/95
5.0U
l.OU
2.4
180
l.OU
l.OU
4.5
110
8.1
2.0J
0.149
0.0385
86.3
O.OIU
0.02U
0.146
O.OSU
12.2
0.541
2.23
31.4
0.0205
293
54.4
0.277
NA
NA
18.1
NA
MW-UZ
08/09/J5
8
l.OU
2.2
190
l.OU
l.OU
3.8
110
4.7
5.0J
0.145
0.0303
89.8
O.OIU
0.02U
0.166
O.OSU
12.5
0.432
U44
30.2
0.029
293
56.4
0.396
NA
NA
17.2
NA
MW-U3
08/08/95
5.0U
l.OU
3.3
550
2.2
l.OU
6.3
330
21
2.01
0.10U
0.02U
88.8
O.OIU
0.02U
0.0596
O.OSU
12.6
0.321
2.46
32
0.0184
298
54.9
0.34
NA
NA
18
NA
MW-EE1
01/08/95
5.0U
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
0.10U
0.281
9.42
O.OIU
0.02U
0.406
O.OSU
10.3
0.186
1.96
30.5
O.OIU
68.7
55.7
O.OSU
NA
NA
5.0U
NA
01/09/95
8
l.OU
l.OU
1.1
l.OU
l.OU
l.OU
l.OU
l.OU
1.01
0.10U
0.384
10.6
0.01U
0.02U
0.311
O.OSU
9.68
0.118
1.26
29.9
0.0111
59.9
55.7
O.OSU
NA
NA
6.33
NA
MW-I23
08/01/95
7.7
I.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
5.0J
0.10U
0.08
10.4
O.OIU
0.02U
1.16
O.OSU
10.7
0.211
2.18
30.1
0.01U
73.9
55.2
0.05U
NA
NA
5.0U
NA
MW-D1
7.6
l.OU
l.OU
6
l.OU
l.OU
l.OU
3.3
l.OU
2.01
0.109
0.0655
21.9
O.OIU
0.02U
0.108
O.OSU
6.28
0.236
1.6
30.1
0.0127
92.9
54.2
0.053
NA
NA
5.0U
NA
MW-DZ
08/0905
5.0U
l.OU
l.OU
1.6
l.OU
l.OU
l.OU
l.OU
l.OU
3.0J
0.122
0.02U
16.8
0.01U
0.02U
0.10U
O.OSU
4.62
0.267
1.0U
29.8
0.0153
65.6
53.7
0.05U
NA
NA
5.0U
NA
MW-D3
08/08/95
5.0U
1.0U
l.OU
1.9
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
0.11
0.0462
13.9
O.OIU
0.02U
0.088
0.05U
5.23
0.2
1.73
29.6
0.0102
64.3
5C7
O.OSU
NA
NA
5.0U
NA
RW-D4
01/01/JS
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
1.12
0.02U
22.4
O.OIU
0.02U
1.48
0.05U
4.06
0.189
1.51
29.4
0.0156
NA
NA
NA
NA
NA
NA
NA
MW-DS
NA
NA
NA
nA
NA
iirt
NA
NA
NA
NA
NA
NA
0.112
0.0281
32.4
O.OIU
0.02U
0.1U
O.OSU
4.76
0.4
1.09
29.1
0.0208
NA
NA
NA
NA
NA
NA
MW-Df
NA
NA
MA
rtrt
MA
n/v
NA
ll/V
MA
li/l
NA
NA
0.506
0.045
24.9
O.OIU
0.02U
0.676
O.OSU
5.01
0.543
1.3
29.8
0.0148
NA
NA
NA
MA
rtn
NA
NA
Notes:
U = substance not detected; associated value is detection limit
NA - parameter not analyzed.
* Average value of replicate samples.
J = estimated value.
-------
Table C-4. Summary of Analytical Data-October
00
SAMPLE
Date
SUBSTANCE DETECTED
VOCi (mlorograms/liter):
Acetone
Bromodichlorometnane
Chloroform
Chloroemane
1,1-Dichloroethane
1,1-Dichloroethene
cis-1 ,2-Dichloroethene
trans-1 ,2-Dichloroethene
Methylene Chloride
Tetrachloroethene
1,1,1-Trichloroethane
Toluene
Trichloroethene
Vinyl chloride
Tentatively Identified Compounds (Total)
Metals (milligrams/liter):
Aluminum
Barium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Potassium'
Sodium
Zinc
Wet Chemistry (milligranu/Uter):
Bicarbonate Alkalinity
Chloride
Nitrate/Nitrite Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
Sulfate
Total PboiphoUpld Fatty Adds:
(Average: picomoles/literi*
MW-U1
10/11/95
S.OU
l.OU
l.OU
l.OU
3.9
1.1
320
1.7
l.OU
l.OU
5.6
l.OU
120
53
l.OU
0.1U
0.0402
92.1
0.03U
0.02U
0.1U
0.05U
12
0.59
1.99
31.1
0.02U
299
45.4
0.19
0.19
0.01U
15.8
91
MW-TJ2
10/12/95
S.OU
l.OU
l.OU
l.OU
5.4
1.2
450
1.9
l.OU
l.OU
7.7
l.OU
160
79
l.OU
0.1U
0.0305
95.6
0.03U
0.02U
0.1U
0.05U
12.3
0.461
1.78
31.4
0.02U
299
46.4
0.31
0.298
0.0118
15.5
115
. MW-U3
10/11/95
S.OU
l.OU
l.OU
2
5.8
1.2
370
1.9
1.0U
l.OU
7.9
1.0U
ISO
49
l.OU
0.1U
0.02U
88.8
0.01U
0.02U
0.1U
O.OSU
12.6
0.321
2.46
32
0.0184
299
48
0.269
0.269
0.01U
16.7
492
MW-FE1
10/1105
5.0U
l.OU
1.0U
l.OU
1.0U
l.OU
1.2
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
2.5J
0.1U
0.0599
7.72
0.03U
0.02U
0.184
O.OSU
9.01
0.0716
2.22
33.3
0.02U
55.8
47.6
O.OSU
0.05U
0.01U
S.OU
56
MW-FE2
10/12/95
5.0U
l.OU
l.OU
1.0U
l.OU
l.OU
2
l.OU
1.0U
l.OU
l.OU
l.OU
l.OU
l.OU
3.61
0.1U
0.14
9.17
0.03U
0.02U
0.203
0.05U
9.68
0.079
2.17
33.9
0.02U
60
49.5
O.OSU
0.05U
0.01U
S.OU
36
MW-FE3
10/11/95
5.0U
1.0U
l.OU
l.OU
2.2
l.OU
3.8
l.OU
l.OU
l.OU
1.0U
l.OU
1.0U
2.3
3.3J
0.1U
0.02U
9.61
0.03U
0.02U
0.523
O.OSU
10.5
0.0706
2,22
33.1
0.02U
65.7
48.4
O.OSU
O.OSU
0.01U
S.OU
20
MW-D1
10/11/95
5.6
l.OU
1.0U
l.OU
l.OU
1.0U
5
1.0U
1.0U
l.OU
l.OU
l.OU
1.2
1.0U
1.01
0.1U
0.05
21.3
0.03U
0.02U
0.1U
0.05U
5.51
0.231
1.7
32.5
0.02U
77.7
48.7
O.OSU
O.OSU
0.01U
5.0U
438
MW-D2
10/12/95
5.0U
l.OU
l.OU
I.OU
1.0U
l.OU
7.5
1.0U
1.0U
l.OU
l.OU
l.OU
1.5
1.2
l.OU
0.1U
0.02U
15
0.03U
0.02U
0.10U
0.05U
4.25
0.194
1.39
32.8
0.02U
64.7
48.7
0.05U
O.OSU
0.01U
5.0U
325
MW-D3
10/11/95
S.OU
1.0U
1.0U
l.OU
1.0U
l.OU
2
1.0U
I.OU
l.OU
l.OU
l.OU
l.OU
1.0U
1.0U
0.1U
0.0386
15
0.03U
0.02U
0.1U
O.OSU
5.01
0.23
1.72
32.9
0.02U
59.8
49
O.OSU
O.OSU
0.01U
S.OU
245
MW-D4
10/11/95
- -
NA
NA
NA
. NA
NA
NA
NA
NA
NA
NA , .
NA
NA
. . NA ..
. . NA ..-...
V - NA , ',
0.17
0.132
64.8 .
0.038.
0.02U
1.16
O.OSU
9.08
1.36
. 1.18
33.5
0.02U
NA
NA
NA
. NA
NA
NA
1.774
MW-D5
10/12/95
NA
. NA
NA
NA
NA
NA
' NA
NA
NA
NA
NA
NA
NA
NA
NA
.0.1U
0.0454
. 28.6
0.03U
0.02U
0:233
O.OSU
4.4
0,719
1.05
33
0.02U
NA
NA
NA
NA
NA
NA
602
MW-D6
10/11/95
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
. . NA
0.712
0.0258
30.2
0.03U
0.02U
0.541
O.OSU
5.16
0.321
1.52
34.8
0.02U
NA
NA
NA
NA
NA
NA
S65
Notes:
U - jubilance not detected.
NA - parameter not analyzed.
* Average value of replicate samples.
Jซ estimated value.
-------
Table C~5. Sutnmaiy of Analyical Data-November
SAMPLE
Dปte
SUBSTANCE DETECTED
VOCs (mfcropims/Iler)!
Acetone
Brotnodichioromethaffle
Chloroform
Chloroethane
l.l-Dichloroethane
1,1-Dichloroelheiie
cis-l,2-Dichloroethene
tran5-l,2-DichIoroe those
Methylene Chloride
Tetrachloroettiene
1 , 1 , 1-TricMoroethane
Toluene
Tiichloroediene
Vinyl chloride
Tentatively Identified Compounds (Total)
Metals (milligrams/liter):
22 Aluminum
OO
Barium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Potassium
Sodium
Zinc
Wet Chemistry (milligrams/liter):
Bicarbonate Alkalinity
Chloride
Nitrate/Nitrite Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
Sulfatc
Total Pbosphollpid Fatty Adds:
(Average: oicomoles/Iiter)*
MW4J1
iimns
5.0U
I.OU
I.OU
I.OU
1.1
I.OU
98
I.OU
I.OU
I.OU
3.3
I.OU
32
7.9
8.01
0.2U
0.0342
87.5
0.01U
0.02U
0.165
O.OSU
11.9
0.468
1.65
28
0.02U
259
40.8
0.125
0.11
0.153
13.1
NA
MWJUZ
1UWK
5.0U
I.OU
I.OU
I.OU
1.8
I.OU
140
I.OU
I.OU
I.OU
4.4
I.OU
65
10
8.41
0.2U
0.0284
89.9
0.01U
0.02U
0.0728
0.05U
11.9
0.345
1.75
27.7
0.02U
272
42.5
0.175
0.157
0.018
14.4
NA
MW-U3
HAMS
5.0U
I.OU
1.0U
I.OU
Z7
I.OU
240
1.9
I.OU
I.OU
6.9
I.OU
110
25
7.1J
0.2U
0.02U
89.9
0.01U
0.02U
0.0506
O.OSU
12
0.269
1.49
28.7
0.02U
283
43.8
0.19
0.171
0.0192
15.3
NA
Mw-m
U/09/JS
5.0U
I.OU
1.0U
I.OU
I.OU
I.OU
1.04
I.OU
.ou
.ou
.ou
.ou
.ou
.ou
4.3J
0.2U
0.0492
8.12
0.01U
0.02U
0.144
O.OSU
8.38
0.0534
2.01
27.7
0.02U
41.8
43.6
0.05U
O.OSU
0.01U
5.0U
NA
Mw-m
WOU9S
5.0U
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
2.0J
0.2U
0.0974
7.96
0.01U
0.02U
0.2
O.OSU
8.06
0.0598
1.86
28.2
0.02U
44.3
45.8
O.OSU
O.OSU
0.01U
5.0U
NA
MW-FE3
U/W95
5.0U
I.OU
I.OU
I.OU
3.9
I.OU
IS
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
1.6
3.81
0.2U
0.02U
8.88
0.01U
0.02U
0.506
O.OSU
10.3
0.0453
1.93
28.1
0.02U
50.3
42.6
O.OSU
0.03U
0.01U
5.0U
NA
MW-D1
UflWS
5.0U
I.OU
I.OU
I.OU
I.OU
I.OU
4.6
I.OU
I.OU
I.OU
I.OU
I.OU
1.6
I.OU
I.OU
0.2U
0.0422
20.3
0.01U
0.02U
0.134
O.OSU
4.76
0.161
1.23
23.7
0.02U
55.5
37.6
O.OSU
O.OSU
0.01U
5.0U
NA
MW-B2
1WWS
5.0U
I.OU
I.OU
I.OU
I.OU
I.OU
4.2
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
2.01
0.2U
0.02U
13.4
0.01U
0.02U
0.0862
O.OSU
3.72
0.161
1.27
23.2
0.02U
63.7
37.9
O.OSU
O.OSU
0.01U
5.0U
NA
MW-B3
_J1/OOT5
8
I.OU
I.OU
I.OU
I.OU
I.OU
2.8
I.OU
1.3
I.OU
I.OU
I.OU
I.OU
I.OU
I.OU
0.02U
0.0341
10.3
0.01U
0.02U
0.134
0.05U
4.27
0.0733
1.4
22J
0.02U
48.8
38.7
O.OSU
0.05U
0.01U
S.OU
NA
MW-D4
U/09/JS
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.735
0.0275
33.3
0.01U
0.02U
1.1
O.OSU
5.58
0.34
1.26
21.1
0.02U
NA
NA
NA
NA
NA
NA
NA
MW-D5
11/IW95
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.2U
0.0333
30.3
0.01U
0.02U
0.211
O.OSU
4.56
0.452
I.OU
22.1
0.02U
NA
NA
NA
NA
NA
NA
NA
MW-DC
1I/W95
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.435
0.0572
39.3
0.01U
0.02U
0.498
O.OSU
6.72
0.521
1.38
24.8
0.02U
NA
NA
NA
NA
NA
NA
NA
Notes:
U - substance not detected; associated value is detection limit
NA = parameter not analyzed.
* Average value of replicate samples.
J fs estimated value.
-------
Table C-6. Summary of Analytical Data-December
SAMPLE
Date
SUBSTANCE DETECTED
VOCs (micrograms/liter):
Acetone
Bromodichloromethane
Chloroform
Chloroemane
1,1-Dichloroethane
1,1-Dichloroethene
eis-1 ,2-Dicbloroethene
trans-l,2-Dichloroethene
Methylene Chloride
Tetrachloroethene
1,1, 1-Trichloroethane
Toluene
Trichloroethene
Vinyl chloride
Tentatively Identified Compounds (Total)
, Metals (milligrams/liter):
OO Aluminum
VO
Barium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Potassium
Silver
Sodium
Zinc
Wet Chemistry (milligrams/liter):
Bicarbonate Alkalinity
Chloride
Nitrate/Nitrite Nitrogen
Nitrate Nitrogen
Nitrite Nitrogen
Sulfate
Total PhosphoUpid Fatty Adds:
(Average; nicomoles/liter)*
MW-UI
12/05/95
5.0U
l.OU
l.OU
l.OU
3.4
l.OU
180
l.OU
l.OU
1.0U
13
l.OU
110
21
4.1J
0.2U
0.0387
92.5
0.01U
0.02U
0.1U
0.05U
12.9
0.494
1.87
0.01U
30.5
0.0129
311
47.2
0.23
0.2
0.0299
16.3
19
MW-U2
12/06/95
5.0U
l.OU
l.OU
l.OU
3.6
l.OU
240
l.OU
l.OU
l.OU
11
l.OU
120
22
3.6J
0.2U
0.0252
90.6
0.01U
0.02U
0.1U
0.05U
12.7
0.388
1.93
0.01U
29.4
0.0119
291
47.4
0.269
0.238
0.0305
17.2
66
MW-U3
12/05/95
5.0U
l.OU
l.OU
l.OU
3.9
1.0U
270
l.OU
l.OU
l.OU
13
l.OU
130
22
4.4J
0.2U
0.02U
90.7
0.01U
0.02U
0.1U
0.05U
12.9
0.289
1.97
0.01U
30.3
0.0125
293
48
0.19
0.169
0.0209
16.3
54
MW-FE1
12/05/95
5.0U
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
i.OU
l.OU
2.01
0.2U
0.0474
12.7
0.01U
0.02U
0.238
0.05U
10.4
0.0958
2.11
0.01U
29.9
0.01U
9.95
48.3
0.05U
0.05U
0.01U
5.0U
10
MW-FE2
12/06/95
5.0U
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
l.OU
3.2J
0.2U
0.102
9.6
0.01U
0.02U
0.158
0.05U
7.33
0.0574
1.86
0.01U
29.6
0.01U
47.8
49.2
0.05U
0.05U
0.01U
5.0U
72
MW-FE3
12/05/95
5.0U
1.0U
l.OU
l.OU
2.7
l.OU
4.3
l.OU
1.0U
l.OU
1.0U
l.OU
l.OU
4.1
3.21
0.2U
0.02U
9.98
0.01U
0.02U
0.601
0.05U
8.29
0.128
1.5
0.01U
28.6
0.01U
43.8
48.6
0.05U
0.05U
0.01U
5.0U
114
MW-D1
12/05/95
5.0U
l.OU
l.OU
l.OU
l.OU
l.OU
2.5
l.OU
.OU
.OU
.OU
.OU
.OU
.OU
1.3J
0.2U
0.0363
21
0.01U
0.02U
0.148
0.05U
5.5
0.16
1.47
0.01U
26.5
0.01U
75.7
45.3
0.05U
0.05U
0.01U
5.0U
1,005
MW-D2
12/06/95
5.0U
l.OU
l.OU
l.OU
l.OU
l.OU
5.6
l.OU
l.OU
l.OU
l.OU
l.OU
0.911
l.OU
6.21
0.2U
0.02U
15.4
0.01U
0.02U
0.1U
0.05U
4.23
0.195
1.02
0.01U
23.4
0.01U
56.5
42.8
O.OSU
0.05U
0.01U
5.0U
1,508
MW-D3
12/05/95
5.0U
l.OU
l.OU
l.OU
l.OU
l.OU
5.4
l.OU
l.OU
1.0U
1.0U
l.OU
l.OU
l.OU
1.0U
0.02U
0.0411
16.6
0.01U
0.02U
0.128
O.OSU
6.65
0.238
1.78
0.01U
27.1
0.01U
61.8
45.8
O.OSU
0.05U
0.01U
5.0U
1,601
MW-D4
12/05/95
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.325
0.0231
28.5
0.01U
0.02U
0.554
O.OSU
4.96
0.318
1.16
0.01U
20
0.0114
NA
NA
NA
NA
NA
NA
2,480
MW-D5
12/06/95
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.2U
0.0338
33.6
0.01U
0.02U
0.159
O.OSU
5.95
0.174
l.OU
0.01U
15.5
0.0115
NA
NA
NA
NA
NA
NA
3.450
MW-D6
12/05/95
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0.974
0.0578
43.8
0.01U
0.02U
1.06
O.OSU
8.47
0.377
1.23
0.01U
23.9
0.014
NA
NA
NA
NA
NA
NA
2,482
Notes:
U - substance not detected; associated value is detection limit.
NA = parameter not analyzed.
I a estimated concentration; reported value is below PQL.
* Average value of replicate samples.
-------
-------
-------
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