United States
          Environmental Protection
          Agency
            Office of Research and
            Development
            Washington DC 20460
EPA/540/R-97/509
May 1999
vvEPA
  DOE
Sandia National
Laboratories In Situ
Electrokinetic Extraction
Technology

Innovative Technology
Evaluation Report
                SUPERFUND INNOVATIVE
                TECHNOLOGY EVALUATION

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                                   EPA/540/R-97/509
                                       May 1999
  Sandia National Laboratories
In Situ Electrokinetic Extraction
             Technology


 Innovative Technology Evaluation Report
           National Risk Management Research Laboratory
             Office of Research and Devefopment
             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.  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 hdw 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, watpr 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
This report evaluates an in situ electrokinetic extraction system's ability to remove hexavalent chromium in the form of
chromate ions from soil under unsaturated conditions. Specifically, this report discusses performance and economic data from
a Superfund Innovative Technology Evaluation (SITE) demonstration of an In Situ Electrokinetic Extraction (ISEE) system
developed by Sandia National Laboratories (SNL).

The ISEE system demonstrated combines electrokinetic and lysimeter technologies. The lysimeter technology hydraulically
and electrically creates a continuum between fluid in the anode casings (anolyte)  and  soil pore  water, thereby enabling
extraction of the chromate ions in the anolyte while the anolyte is held in the electrode casing through application of a vacuum.
This feature allowed removal of chromate from unsaturated soil during the demonstration without significantly altering the soil
moisture content.
The  ISEE system developed by SNL was demonstrated at the U.S. Department of Energy SNL Chemical Waste Landfill
(CWL) site's Unlined Chromic Acid Pit (UCAP) in Albuquerque, New Mexico, from May 15 to November 24,  1996.  The
system was housed in two buildings: a control trailer and a temporary structure.  The electrode system of the ISEE system
consisted of an anode row oriented east to west and four rows of cathodes parallel to the anode row, two rows to the north and
two rows to the south of the anode row.  The entire system was operated for a total of 2,727 hours during 13 tests performed
in six phases. The first 12 tests were performed to determine the preferred operating conditions for Test 13, which consisted
of system performance testing under SNL's preferred operating conditions for the SITE demonstration.

Approximately 520 grams (g) of hexavalent chromium was removed during the demonstration. Overall hexavalent chromium
removal rates varied  from 0.074 gram per hour (g/hour) during Test 1  to 0.338  g/hour during Test 5.  Overall hexavalent
chromium removal efficiencies varied from 0.0359 gram per kilowatt-hour (g/kW-h) during Test 7 to 0.136 g/kW-h during
Test 13.  More than 50 percent of the postdemonstration soil samples exceeded the toxicity characteristic leaching procedure
(TCLP) limit of 5 milligrams per liter (mg/L) for total chromium.  The soil TCLP leachate concentrations that were above the
TCLP limit ranged from 6 to 67 mg/L. Downtime during system operation ranged from 0 percent during Test 11 to 66 percent
during Test 1.  Over the entire demonstration, the ISEE system was  on line 64 percent of the time.

Economic data indicate that the costs for treating 16 cubic yards (yd3) of hexavalent chromium-contaminated soil with the ISEE
system configuration used during Test 13 are about $1,400 per yd3 for 200 g of hexavalent chromium removed.

The ISEE technology developed by SNL is applicable for treating unsaturated soil contaminated with hexavalent chromium.
According to SNL, this technology can be modified to treat saturated contaminated soil and to remove contaminants dissolved
in pore water other than chromate.  A full-scale, commercial system has not yet been developed. SNL maintains that a full-
scale system would  be significantly be improved over the system tested during the demonstration.  Therefore, further
performance and cost analyses should be performed on a full-scale system.
                                                        iv

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                                        Contents
Notice	ii
Foreword	iii
Abstract	iv
Acronyms, Abbreviations, and Symbols	ix
Conversion Factors	xi
Acknowledgments	xii

Executive Summary	.'	1
1   Introduction	7
    1.1 Brief Description of SITE Program and Reports	.'	7
        1.1.1    Purpose, History, and Goals of the SITE Program	'	7
        1.1.2    Documentation of SITE Demonstration Results	8
    1.2 Purpose and Organization of the ITER	8
    1.3 Background Information on the Demonstration of the SNLISEE System under
        the SITE Program	9
    1.4 Technology Description	j	9
        1.4.1    Process Chemistry	.:	9
                1.4.1.1   Electromigration	10
                1.4.1.2   Electroosmosis	11
        1.4.2    SNL ISEE System	12
                1.4.2.1   Electrode System	12
                1.4.2.2   Water Control System	:	16
                1.4.2.3   Vacuum Control System „	17
                1.4.2.4   Power Supply  System	17
                1.4.2.5   Monitoring System	18
                1.4.2.6   Ancillary Equipment	19
        1.4.3    Innovative Features of the Technology	.;	19
    1.5 Applicable Wastes	20
    1.6 Key Contacts	.;	20

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                               Contents (continued)
2   Technology Effectiveness and Application Analysis	22
    2.1  Overview of ISEE System SITE Demonstration	22
        2.1.1   Project Objectives	22
        2.1.2   Demonstration Approach	23
        2.1.3   Sampling and Analytical Procedures	23
    2.2  SITE Demonstration Results	25
        2.2.1   Removal of Hexavalent Chromium from Site Soil	26
        2.2.2   Compliance with TCLP Regulatory Criterion for Total Chromium	33
        2.2.3   Removal of Trivalent Chromium from Site Soil	33
        2.2.4   Operating Problems	33
    2.3  Factors Affecting Performance	33
        2.3.1   Waste Characteristics	33
        2.3.2   Operating Parameters	37
        2.3.3   Maintenance Requirements	38
    2.4  Site Characteristics and Support Requirements	38
        2.4.1   Site Access, Area, and Preparation Requirements	38
        2.4.2   Climate Requirements	38
        2.4.3   Utility and Supply Requirements	38
        2.4.4   Support System Requirements	38
        2.4.5   Personnel Requirements	39
    2.5  Material Handling Requirements	39
    2.6  Technology Limitations	;	38
    2.7  Potential Regulatory Requirements	39
        2.7.1   Comprehensive Environmental Response, Compensation, and Liability Act	39
        2.7.2   Resource Conservation and Recovery Act	41
        2.7.3   Clean Air Act	42
        2.7.4   Toxic Substances Control Act	42
        2.7.5   Atomic Energy Act and Resource Conservation and Recovery Act	42
        2.7.6   Occupational Safety and Health Administration Requirements	43
    2.8  State and Community Acceptance	43
3   Economic Analysis	44
    3.1  Introduction	44
    3.2  Issues and Assumptions	44
    3.3  Basis for Economic Analysis	45
                                              VI

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                               Contents (continued)
        3.3.1    Site and Facility Preparation Costs	49
        3.3.2    Permitting and Regulatory Costs	49
        3.3.3    Equipment Costs	,	.	49
        3.3.4    Startup and Fixed Costs	50
        3.3.5    Labor Costs	.,	50
        3.3.6    Supplies and Consumables Costs	50
        3.3.7    Utilities Costs	50
        3.3.8    Effluent Treatment and Disposal Costs	50
        3.3.9    Residuals and Waste Shipping, Handling, and Transport Costs	51
        3.3.10   Analytical Costs	j	51
        3.3.11   Facility Modification, Repair, and Replacement Costs	51
        3.3.12   Site Restoration Costs	51
    3.4 Conclusions	51
4   Technology Status	52
5   References	•.	54

Appendix

Vendor's Claims for the Technology	•	55


                                         Figures


1-1 Electrokinetic Phenomena in a Soil Pore	10
1-2 ISEE System Schematic Diagram	13
1-3 ISEE System Electrode Layout	14
1-4 Anode/Cathode and Cold Finger Cathode Construction Cross Sections	15
2-1 Hexavalent Chromium Removal Efficiency Per Electrode for Test 13	28
2-2 Hexavalent Chromium Removal Rate Per Electrode for Test 13	29
2-3 Spatial Distribution of Hexavalent Chromium Concentrations In Soil	30
2-4 Spatial Distribution of TCLP Leachable, Chromium Concentrations in Soil	34
2-5 Spatial Distribution of Total Chromium Concentrations in Soil	35
                                              VII

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                                        Tables
ES-lSuperfund Feasibility Evaluation Criteria for the ISEE Technology	5
1-1 Correlation Between Superfund Feasibility Evaluation Criteria and ITER Sections	8
1-2 Monitoring System Parameters	18
1-3 Comparison of In Situ Treatment Technologies for Metals-Contaminated Soil	21
2-1 Test Matrix for SNL ISEE System Demonstration	24
2-2 SNL ISEE System Preferred Operating Conditions	25
2-3 SNL ISEE System Performance Data	27
2-4 Statistical Summary of Hexavalent and Total Chromium Analytical Results	32
2-5 System Shutdown Information	:	37
2-6 Summary of Applicable Regulations	40
3-1 Estimated Costs for Treatment Using the SNL ISEE System	46
3-2 Estimated Cost Percentages for Treatment Using the SNL ISEE System	48
                                             VII!

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          Acronyms, Abbreviations, and Symbols
 AAA          Abbreviated analytical approach
 AEA          Atomic Energy Act
 amp           Ampere
 ARAR         Applicable or relevant and appropriate requirement
 bgs            Below ground surface
 CAA          Clean Air Act
 CERCLA       Comprehensive Environmental Response, Compensation, and Liability Act of 1980
 CFR           Code of Federal Regulations
 CWL          Chemical waste landfill                   •;
 DC            Direct current                            .
 DOE           U.S. Department of Energy
 EPA           U.S. Environmental Protection Agency
 g              Gram
 g/hour         Gram per hour
 g/kW-h         Gram per kilowatt-hour                    ;
 ICP            Inductively coupled plasma
 ISEE           In situ electrokinetic extraction
 ITER          Innovative technology evaluation report
 kW            Kilowatt                                :
 kW-h          Kilowatt-hour
 LDR           Land Disposal Restriction
 L/min          Liter per minute
 mg/kg          Milligram per kilogram
 mg/L           Milligram per liter
 m/s            Meter per second
 mW-s         Square meter per volt-second
N-s/m2         Newton-second per square meter
N/V2           Newton per square volt
NCP           National Oil and Hazardous Substances Contingency Plan
NPDES         National Pollutant Discharge Elimination System
NRMRL        National Risk Management Research Laboratory
                                     IX

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  Acronyms, Abbreviations, and Symbols (continued)
NSPS          New Source Performance Standard
O&M          Operation and maintenance
ORD           Office of Research and Development
OSHA         Occupational Safety and Health Administration
OSWER        Office of Solid Waste and Emergency Response
PCB           Polychlorinated biphenyl
PPE           Personal protective equipment
ppm           Part per million
psi            Pound per square inch
PVC           Polyvinyl chloride
QA            Quality assurance
QC            Quality control
QAPP         Quality assurance project plan
Quanterra      Quanterra Environmental Services, Inc.
RCRA         Resource Conservation and Recovery Act of 1976
SAP           Sampling and analysis plan
SITE          Superfund Innovative Technology Evaluation
SNL           Sandia National Laboratories
TCLP         Toxicity characteristic leaching procedure
TER           Technology evaluation report
TSCA         Toxic Substances Control Act
UCAP         Unlined chromic acid pit
V             Volt
V/m           Volt per meter
VOC          Volatile organic compound
yd3            Cubic yard
 ug/L         Microgram per liter
>             Greater than
<             Less than

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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
                                           XI

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                                       Acknowledgments
This report was prepared under the direction and coordination of Mr. Randy Parker, U.S. Environmental Protection Agency
(EPA) Superfund Innovative Technology Evaluation (SITE) program project manager of the National Risk Management
Research Laboratory (NRMRL) in Cincinnati, Ohio. Contributors and reviewers for this report were Sam Hayes and Ed Earth
of EPA NRMRL, Cincinnati, Ohio; and Dr. Eric Lindgren of Sandia National Laboratories, Albuquerque, New Mexico. This
report was prepared for EPA's SITE program by Dr. Kirankumar Topudurti, Ms. Cristina Radu, Mr. Shin Ahn, and Ms. Linda
Hunter of Terra Tech EM Inc.
                                                    XI!

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                                       Executive Summary
 The electrokinetic extraction technology is a treatment
 process that facilitates the in situ extraction of metals from
' unsaturated and saturated soil. The In Situ Electrokinetic
 Extraction (ISEE) system developed by Sandia National
 Laboratories  (SNL) focused on  the  remediation  of
 hexavalent chromium-contaminated soil under unsaturated
 conditions (optimal moisture content in the range 10 to 12
 percent by weight, representing approximately 25 percent
 saturation). The SNL ISEE system was accepted into the
 Superfund Innovative  Technology Evaluation  (SITE)
 Demonstration program in  Summer*  1994 and was
 demonstrated at the U.S. Department of Energy (DOE)
 SNL Chemical Waste Landfill  (CWL) site's  Unlined
 Chromic Acid Pit (UCAP) in Albuquerque, New Mexico,
 from May 15 to November 24, 1996. This demonstration
 was funded by DOE's Office of Science and Technology
 through the Subsurface Contamination Focus Area. The
 ISEE system was independently evaluated under the SITE
 program.

 The purpose of this innovative  technology  evaluation
 report (ITER) is  to present information that will assist
 Superfund decision-makers in evaluating the ISEE system
 developed by SNL  for application to  a particular
 hazardous waste  site cleanup. The report provides  an
 introduction  to the  SITE  program  and ISEE  system
 technology (Section   1),  analyzes  the .technology's
 effectiveness and applications (Section  2),  analyzes the
 economics of using  the ISEE   system  to  treat soil
 contaminated with hexavalent chromium in the form of
 chromate (Section 3), summarizes the technology's status
 (Section 4),  and presents a list  of references  used  to
 prepare the ITER (Section 5). Vendor's claims for the
 ISEE system are presented in the appendix.

 This  executive summary briefly  describes  the ISEE
 technology and system, provides an overview of the SITE
 demonstration of the technology, summarizes the SITE
 demonstration results, discusses the economics of using
the ISEE system to treat soil contaminated with hexavalent
chromium in the form of chromate, and discusses the
Superfund feasibility  evaluation criteria for the  ISEE
system.

Technology and System Description

The ISEE system developed by SNL applied electrokinetic
technology to unsaturated soil to  remove  hexavalent
chromium.  The application of current to the soil-water
system results in the following: (1) ionic species in the soil
pore water migrate to the oppositely charged electrode (a
phenomenon  '. called  electromigration),  (2)  charged
particles in the soil pore water migrate to the oppositely
charged electrode (a phenomenon called electrophoresis),
(3) bulk water; moves toward the cathode (a phenomenon
called  electrobsmosis), and  (4) electrolysis reactions
occur at the 'electrodes.   The combination of  these
phenomena results in the movement of ionic contaminants
toward the electrodes. The direction and rate of movement
will  depend on the charge of the ions (both in terms of
magnitude an
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The operation of the ISEE system was regulated by a water
control system, a vacuum control system, a power supply
system, a monitoring system, and ancillary equipment.

The anodes and  cathodes used at UCAP were designed to
combine electrokinetic and lysimeter technologies. This
combination was necessary to allow the operation of the
system under unsaturated soil conditions.  Lysimeter
technology  hydraulically  and  electrically  creates  a
continuum  between the anolyte and the pore  water,
thereby enabling the extraction of the chromate ions in the
anolyte while the anolyte is held in the electrode casings
through the application of a vacuum. This feature allowed
the removal of chromate from unsaturated soil during the
demonstration  without significantly  altering  the  soil
moisture content.

The ISEE technology developed by SNL is applicable for
treating unsaturated soil contaminated with  hexavalent
chromium.  According to SNL, this technology can be
modified to treat saturated contaminated soil and to
remove contaminants  dissolved in pore water besides
chromate.  Because  other anions will  compete with the
targeted contaminant ions to be removed, it is necessary to
determine the electrical conductivity of soil pore water and
the target ion concentration to determine the applicability
of the ISEE technology.

Overview of the SNL ISEE System SITE
Demonstration

The ISEE system SITE demonstration took place at the
UCAP, which is part of the CWL site  located  within
Technical Area III at SNL. The UCAP is a rectangular pit
measuring about 15  by 45 feet and is 10 feet deep.  The
areal  extent and depth of the area targeted by  the
demonstration was selected based on the highest results of
water soluble chromium concentrations from  sampling
performed  during previous investigations.   During the
demonstration, the system was operated for  a period of
2,727 hours between May 15 and November 24, 1996.

The primary objective of the technology demonstration
was to estimate the amount of hexavalent chromium
removed from soil by the ISEE  system because the ISEE
system is  primarily  designed to remove  hexavalent
chromium. To  accomplish this objective, SNL collected
and analyzed anolyte samples for hexavalent chromium at
its field laboratory throughout the demonstration period.
An  independent check of field  analytical data was
provided by EPA through split sample analysis at an off-
site laboratory.  Field analytical data were subsequently
deemed adequate to estimate the amount of hexavalent
chromium removed from  soil by the ISEE system.
Predemonstration  and postdemonstration soil samples
collected by EPA were analyzed for hexavalent chromium
to verify the hexavalent chromium removal estimate based
on anolyte sample analyses.

The secondary objectives of the technology demonstration
were to determine whether treated soil meets the toxicity
characteristic leaching  procedure  (TCLP)  regulatory
criterion for total chromium and to evaluate the ISEE
system's ability to remove trivalent chromium from site
soil.

To conduct the demonstration, SNL was required to meet
the conditions  of  the  New Mexico  Environmental
Department's Resource  Conservation and Recovery Act
(RCRA) Research,  Development,  and Demonstration
permit for the ISEE system.  Predemonstration testing
results indicated that some of the soil in the demonstration
area is hazardous (EPA waste code D007) because
chromium concentrations exceeded the TCLP criterion for
chromium.   Therefore, the permit required  that SNL
perform postdemonstration TCLP testing to determine the
impact of the  ISEE system  on  soil known  to  be
contaminated. SNL therefore collected a large number of
treated soil  samples for total chromium analysis after
extraction using TCLP.

Because incidental removal of trivalent chromium will
likely be accomplished by the ISEE system, evaluation of
trivalent chromium removal was  a secondary project
objective of this project. To accomplish this objective, the
predemonstration  and postdemonstration soil samples
collected for hexavalent chromium analysis  were also
analyzed  for total chromium  so that the  trivalent
chromium  concentrations could be calculated as the
difference between  the total and hexavalent chromium
concentrations.

During the SITE demonstration, 13 tests were performed
during six phases.  The test areas ranged from 36 to 72
square feet,  and contaminated soil from 8 to 14 feet bgs
was treated.  The first 12 tests were conducted so that SNL
could  determine the preferred operating conditions for
Test  13  and to facilitate the migration of hexavalent
chromium toward the central portion of the test area. Test
13 consisted of system performance testing under SNL's
preferred operating conditions for the SITE demonstration.

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Three sampling events occurred during the ISEE system
SITE demonstration: one of predemonstration soil, one of
anolyte  (electrolyte  from  the anodes),  and  one  of
postdemonstration soil. SNL collected predemonstration
soil samples from various depth in boreholes within and
near the test areas using a 1 -inch-diameter by 24-inch-long
Geoprobe® Large Bore Sampler. SNL extracted a portion
of each sample with water and analyzed the extract for
chromium. Additional sample portions were sent to an
off-site laboratory  in order to have these soil  samples
extracted using TCLP and the  extracts analyzed,  for total
chromium.  EPA used SNL's archived soil samples to
determine total and hexavalent chromium concentrations
in the predemonstration soil.

During operation of the ISEE system, SNL collected
anolyte samples daily and analyzed them for hexavalent
chromium to determine removal rates. To verify these
results, EPA obtained anolyte samples from  all four
operating anodes daily for 8 days. These samples were all
sent to Quanterra for analysis  for hexavalent chromium.
The relative percent differences between the SNL and
Quanterra results varied from  0 to  20 percent indicating
that SNL's  field hexavalent  chromium analyses were
acceptable.

After the demonstration, EPA collected soil samples using
the Geoprobe® from locations near (within 1 foof:  laterally
and 2 inches vertically) the predemonstration sampling
locations and sent these samples to an off-site laboratory
for the same  sort of preparation and  analyses for
hexavalent chromium  and total  chromium  conducted
during predemonstration sampling.  SNL collected a
separate series of Geoprobe® samples and sent them to an
off-site  laboratory for  TCLP extraction  and  total
chromium analysis.

SITE Demonstration Results

Key findings of the ISEE system SITE demonstration are
listed below.

 •  Approximately  520  grams   (g)  of  hexavalent
    chromium  were  removed   during  the   entire
    demonstration.    Overall  hexavalent   chromium
    removal rates varied from 0.074 gram  per  hour (g/
    hour)  during Test 1 to 0.338 g/hour during Test 5.
    Overall hexavalent chromium removal efficiencies
varied from 0.0359 gram per kilowatt-hour (g/kW-h)
during Test 7 to 0.136 g/kW-h during Test 13.

The total mass of hexavalent chromium extracted by
the ISEE system  should have  been verified  by
calculating  the  difference   between  hexavalent
chromiuin mass in treated soil before and after the
demonstration. However, soil results for hexavalent
chromium  exhibited  a  high  spatial  variability
resulting; from (l)the nonhomogeneous distribution
of chrofnate  concentrations  in  soil before  the
demonstration and (2) the fact that the demonstration
was  terminated  before  chromate  removal was
completed. In addition, limited data appear to indicate
that contaminants had likely migrated from  areas
outside  of and near the treatment area.   Thus, a
determination of the mass of hexavalent chromium
removed: based on soil sampling results was not
possible.:

Of the 43 predemonstration soil samples analyzed by
TCLP, 18 exceeded the TCLP limit of 5 milligrams
per liter (mg/L) of total chromium at concentrations
ranging from  5.6 to 103  mg/L, with  a median
concentration  of  15.4 mg/L.    Postdemonstration
results indicate that 18 out of 3 5 soil samples exceeded
the TCIiP regulatory  criterion  for  chromium at
concentrations ranging from 6 to 67 mg/L, with a
median concentration of 20.4 mg/L.

Trivalent  chromium  concentrations were   to  be
determined by calculating the difference between total
and hexavalent chromium concentrations. In general,
the ratio; of trivalent chromium to total  chromium
ranged from 7.6 to 94.9 percent in the predemonstration
samples , and  from 27.6 to 99.6  percent  in the
postdemonstration  samples.  This large  variability
precluded the  calculation of  trivalent  chromium
concentrations as originally intended because it would
have further increased the data variability.  Therefore,
no conclusion was drawn regarding the ISEE system's
ability to; remove trivalent chromium.
        i
The entire system was operated for a total of 2,727
hours during 13 tests performed in six phases. The
first   12  tests  were performed  to  determine the
preferred operating conditions for Test 13. Test 13
consisted of system performance testing under SNL's
preferred  operating  conditions for  the  SITE
demonstration.

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Economics

Based on information provided by SNL and the results and
experiences  gained  from the SITE demonstration, an
economic analysis was performed to examine 12 separate
cost categories for using the ISEE technology to remediate
hexavalent chromium-contaminated, unsaturated  soils.
According to SNL, a full-scale commercial system design
would significantly differ from the system operated during
the demonstration.  In addition, the developer has not
completed a full-scale design  of a commercial  ISEE
system. Therefore,  it is not possible to prepare a cost
estimate for a full-scale ISEE system. Because SNL states
that the  full-scale  treatment  system design will  be
significantly improved based on the performance of the
system used during the demonstration, the treatment cost
of a full-scale system will also differ from the treatment
cost of the system operated during the demonstration.
When the technology is  ready for commercialization.,
further economic analysis should be performed.

Treatment costs were determined  for the ISEE system
configuration used  during  Test 13 (SNL's preferred
operating conditions) to treat 16 cubic yards (yd3) of soil
and remove 200  g of  hexavalent  chromium  (the
approximate  mass of hexavalent chromium removed
during Test 13). Because the treatment volume is only 16
ydj and the ISEE system configuration used during Test 13
is currently  at the pilot-scale level, the cost per yd3 of
treated soil is very high; the estimated treatment costs are
about $1,400 per yd3 for 200 g  of hexavalent chromium
removed.  If SNL is able to further optimize the  ISEE
system  configuration so  that hexavalent  chromium
removal rate increases from that calculated for Test 13,
treatment time and costs will be lower. As mentioned
above, costs from economic analysis of a full-scale ISEE
system would be more indicative of costs of a commercial-
scale ISEE system.

Super-fund Feasibility Evaluation Criteria for the
ISEE System

Table ES-1  briefly  discusses the  Superfund feasibility
evaluation criteria for the ISEE system to assist Superfund
decision-makers  considering  the  technology for
remediation of contaminated  groundwater or soil  at
hazardous waste sites.

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Table ES-1. Superfimd Feasibility Evaluation Criteria for the ISEE Technology
      Criterion
Discussion
      Overall Protection of
      Human Health and the
      Environment
    The ISEE technology is expected to protect human health by lowering the
    concentration of hexavalent chromium in soil under unsaturated conditions.
    According  to the developer, the technology can also treat soil contaminated
    with other heavy metals under both saturated and unsaturated conditions, but
    this capability was not evaluated during the SITE demonstration.

    Overall reduction of human health risk should be evaluated on a site-specific
    basis because VOCs could be stripped from soil during treatment and increase
    VOC soil vapor concentrations and VOC migration in the soil. Also, the system
    effluent (anolyte) contains hexavalent chromium and therefore needs to be
    characterized and handled and disposed of as hazardous waste.

    The technology protects the environment by curtailing  migration of hexavalent
    chromium in soil.

    Protection  of the environment at and  beyon'd the  point of anolyte extraction
    depends on how the anolyte is handled and disposed of.  Protection of the
    environment also depends on the extent of VOC emissions.
     Compliance with
     Applicable or Relevant
     and Appropriate
     Requirements (ARAR)
    According to the developer, the technology has the potential to comply with
    existing federal, state, and local ARARs (for example, TCLP limits) for several
    inorganic  contaminants (for example, chromium). However, about 51 percent
    of the postdemonstration samples did not meet the chromium TCLP limit of 5
    mg/L.
     Long-Term
     Effectiveness and
     Permanence
     Reduction of Toxicity,
     Mobility, or Volume
     Through Treatment
    Human health risk can be reduced to acceptable levels by treating soil to a 1 x
    10"6 excess lifetime cancer risk level.  The time needed to achieve cleanup goals
    depends primarily on contaminated soil characteristics.

    The treatment achieved is permanent because contaminants are contained in
    the anolyte, which is extracted from the soil for disposal.

    Periodic review of treatment system performance is needed because application
    of the technology to contaminated soil at hazardous waste sites is new.


    The technology reduces the volume and mobility of contaminants in soil
    because contaminants are contained in the Anolyte, which is extracted from the
    soil for  disposal,                         :

    The technology can effectively control soil contaminant migration because
    contaminants are contained in the anolyte,  Vvhich is extracted from the  soil for
    disposal.                                !
     Short-Term
     Effectiveness
   About 51 percent of postdemonstration samples did not meet the chromium
   TCLP limit of 5 mg/L.  This failure may be because the developer did not have
   the state permit required to carry out the demonstration for a longer period of
   time.                                   '
     Implementability
   The technology is still in the development stage. No commercial system is
   currently available from SNL.
                             •   State and local permits must be obtained to: operate the ISEE system.

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Table ES-1. Supcrfund Feasibility Evaluation Criteria for the ISEE Technology (continued)
     Criterion
Discussion
      Cost
    Treatment costs vary significantly depending on the size of the treatment
    system used, contaminant characteristics and concentrations, cleanup goals,
    the volume of contaminated soil to be treated, and the length of treatment.
    Economic data indicate that soil remediation costs are very high, perhaps
    because the system demonstrated at UCAP  was not of commercial scale and
    requires significant improvements.
      State Acceptance
    This criterion is generally addressed in the record of decision. State acceptance
    of the technology will likely depend on (1) expected residual contaminant in
    soil, (2) how the anolyte is handled and disposed of, and (3) the steps taken to
    reduce the potential for VOC migration.
      Community Acceptance
    This criterion is generally addressed in the record of decision after community
    responses have been received during the public comment period.  Because
    communities are not expected to be exposed to harmful levels of fugitive
    emissions, the level of community acceptance of the technology is expected to
    be moderate.

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                                             Section 1
                                           Introduction
This section briefly describes the Superfund Innovative
Technology Evaluation (SITE) program and SITE reports;
states the purpose and organization of this innovative
technology evaluation report (ITER); provides background
information on the demonstration of the Sandia National
Laboratories (SNL) In  Situ Electrokinetic Extraction
(ISEE) system under the SITE program; describes the
ISEE technology; identifies  wastes  to  which  this
technology can be applied; and provides a list of key
contacts  for information about  the system and SITE
demonstration.

1.1    Brief Description of SITE Program
       and Reports

This section provides information about the purpose,
history, and goals of the SITE program and about reports
that 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 developmenfand 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 (NRMRL).  The overall goal of the
SITE program is to research, evaluate, test, develop, and
demonstrate  alternative  or   innovative  treatment
technologies that can be used in response actions to
achieve long-term protection of human health and welfare
and the environment.

This ITER wks 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 actual  hazardous waste  sitos or 'under
conditions  that  closely  simulate  actual  waste  site
conditions.  ,

Data collected during the demonstration are used to assess
the performance of the technology, the potential need for
pretreatment and post-treatment processing of the treated
waste, the types of wastes and media that can be treated by
the  technology,  potential treatment system  operating
problems, and approximate capital and operating costs.
Demonstration data  can also  provide insight into  a
technology's i long-term operation  and  maintenance
(O&M) costs and long-term application risks.

Under each1 SITE  demonstration,   a technology's
performance in treating an individual waste at a particular
site  is  evaluated.   Successful  demonstration  of  a
technology at i one site does not ensure its success at other
sites.  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 case
study information.

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

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remediation.  The technology selection process and the
Demonstration  program together provide a means to
perform 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 usually
reported in four documents: the  demonstration bulletin,
technology capsule, technology evaluation report (TER),
and ITER.

The  demonstration   bulletin  provides   a two-page
description  of the  technology  and project  history,
notification that the demonstration was completed, and
highlights of the demonstration results. The technology
capsule provides a brief description of the project and an
overview of the demonstration results and conclusions.

The purpose of the Technology Evaluation Report (TER)
is to consolidate all information and records acquired
during the demonstration.  It contains both a narrative
portion and tables that summarize data. The narrative
portion discusses predemonstration, demonstration, and
postdemonstration  activities,  any deviations  from  the
sampling and analysis plan (SAP) during these activities,
and the impact of such deviations, if applicable. The tables
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 by the EPA
project manager as a reference for responding to public
inquiries and for recordkeeping purposes.  The purpose
and organization of the ITER are discussed below.

1.2    Purpose and Organization of
       the ITER

Information presented in the ITER is intended to assist
Superfund  decision-makers   in  evaluating  specific
technologies for a particular cleanup situation.  Such
evaluations typically involve the nine remedial technology
feasibility evaluation criteria, which 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 ISEE system and
Table 1-1. Correlation Between Superfund Feasibility Evaluation Criteria and ITER Sections
               Evaluation Criterion8
          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	
          2.2.1 through 2.2.3

          2.2.2 and 2.7
          1.4 and 2.2.1
          2.2.1 and 2.2.2

          2.2.1 through 2.2.3
          1.4, 2.2, 2.3, and 2.4
          3.0
          2.8
          2.8
              Note:
                    Source: EPA 1988
                    ARAR = Applicable or relevant and appropriate requirement

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 analyzes  costs associated  with its application.   The
 system's  effectiveness  is  evaluated  based  on  data
 collected during the SITE demonstration and from other
 case studies.  The applicability of the system is discussed
 in terms of waste and site characteristics that could affect
 technology performance, material handling requirements,
 technology limitations, and other factors.

 This  ITER  consists  of five  sections, including this
 introduction.   These sections  and their contents  are
 summarized below.

 •  Section 1, Introduction, presents a brief description of
    the SITE program  and reports, the  purpose and
    organization of the ITER, background information
    about the ISEE system demonstration under the SITE
    program,  a technology description, applicable wastes
    that can be treated, and key contacts for information
    about the ISEE system and SITE demonstration.

 •  Section 2, Technology Effectiveness and Application
    Analysis, presents an overview of the  SNL ISEE
    system SITE demonstration,  SITE demonstration
    results, factors affecting ISEE system performance,
    site characteristics and support requirements, material
    handling   requirements,  technology  limitations,
    potential  regulatory requirements,  and state  and
    community acceptance.

 •  Section 3, Economic Analysis, discusses estimated
    costs,  issues and assumptions,  and the basis for the
    economic analysis.

 •  Section   4,  Technology  Status,  discusses  the
    developmental status of the ISEE system.

 •  Section 5, References, lists references used to prepare
    this ITER.

In addition to these sections, this ITER has an appendix,
Vendor's Claims for the Technology.

1.3   Background Information on the
       Demonstration of the SNL  ISEE
       System Under the SITE Program

The SNL  ISEE  system was  accepted  into the SITE
Demonstration program  in Summer 1994.   The ISEE
system was demonstrated  at  the  U.S.  Department of
Energy (DOE) SNL  Chemical Waste Landfill (CWL)
 site's Unlined Chromic Acid Pit (UCAP) in Albuquerque,
 New Mexico^ from May 15 to November 24, 1996. This
 demonstration was funded by DOE's Office of Science
 and Technology through the Subsurface Contamination
 Focus Area.   The  ISEE  system was independently
 evaluated under the SITE program.

 1.4    Technology Description

 This section describes the ISEE process chemistry, ISEE
 treatment  system,  and  innovative   features  of  the
 technology.  ]

 1.4.1  Process Chemistry

 The ISEE technology is a treatment process that facilitates
 the in situ extraction of metals from unsaturated and
 saturated  soil.    The  electrokinetic  removal system
 developed  by  SNL  focused  on the  remediation  of
 hexavalent chromium-contaminated soil under unsaturated
 conditions  (moisture content as low  as 7 percent by
 weight, representing approximately 25 percent saturation
 in laboratory studies) (Lindgren and others 1991).
             I

 The application of electrokinetics to various types  of
 unsaturated  soils, including clays and sands, has been
 studied by  numerous  investigators.    Electrokinetic
 systems apply low-level direct current (DC) on the order
 of milliamperes per square centimeter between electrodes,
 thus establishing an electrical potential on the order  of
 volts per centimeter across the electrodes. Electrokinetic
 systems are effective as long as the pore water in the soil
 can  maintain  the  electrical  potential between the
 electrodes (Lindgren and others 1991).

 The application of the current  to the soil-water system
 under saturated or unsaturated  conditions results in the
 following: (1) ionic species in the soil pore water migrate
 to the oppositely charged electrode (a phenomenon called
 electromigration), (2) charged particles in the soil pore
 water migrate to the  oppositely charged electrode  (a
 phenomenon  called electrophoresis),  (3) bulk water
 moves  toward  the cathode   (a phenomenon  called
 electroosmosis), and (4) electrolysis reactions occur at the
 electrodes (Hunter 1981). Figure 1-1 is a diagram of these
phenomena. The combination of these phenomena results
in the movement of  ionic  contaminants toward the
electrodes.   The direction and rate of movement will
depend on the  charge of the  ions (both in  terms of
magnitude and polarity), the degree to which the ions

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       Hydroxyl Ion
                                                                                          Soil Particle
                                                                                            Hydrogen Ion
                                            ®@    ©  ©  ©
                                                Charged
                                            <  Particle
                                      Cathode
          Electrical
           Double
           layer
                                                                                      Soil Particle
Figure 1-1.  Electrokinetic phenomena in a soil pore.
adsorb to the soil particles,  and the magnitude of the
electroosmosis flow velocity.  Contaminants arriving at
the electrodes can be removed by extracting the pore water
near  the  electrodes,   electroplating   or  adsorbing
contaminants  onto the  electrodes,  precipitating  and
ooprecipitating  contaminants  at  the   electrodes,  or
complexing the  contaminants with ion-exchange resins
(Mattson and Lindgren 1993).

The two  most  important  transport mechanisms  in
electrokinetic remediation are  electromigration  and
electroosmosis.   Previous testing does  not prove that
electrophoresis  is  an  efficient  transport  mechanism
because the flow of colloid particles requires large pore
spaces and the  colloid particles are likely to become
mechanically lodged in the pore space and taken out of
suspension.  On the  other hand, electromigration and
electroosmosis  follow the potential gradient and are
independent   of  pore   size.  Electromigration   and
electroosmosis are briefly discussed below.
1.4.1.1 Electromigration

Electromigration represents the transport of ionic species
in pore fluid across the soil mass under the influence of an
electric field. These ionic species may include anions such
as CrO4%  HAsO4% SeO4% and carbonate complexes of
uranium and cations such as Cr3^ Na+, Fe2+, and Fe3+.

The electromigration velocity of an ion in a dilute solution
is a function of the electrical ionic mobility of a species
(the ionic transport rate under the voltage gradient). A
tortuosity term can be incorporated into the general ionic
transport equation to account for the nonlinear path of ion
travel in  a soil  matrix (Shapiro  1990).   Equation 1-1
presents a modified version of the general ionic transport
equation, which is specific for movement under a voltage
gradient.
                            dV
                                             (i-i)
                                                     10

-------
where:
dV/dx  =
               electromigration velocity (meter per
               second [m/s])
               electric ionic mobility (square meter per
               volt-second [m2 /V-s])
               tortuosity (dimensionless)
               voltage gradient (volt per meter [V/m])
1.4.1.2 Electroosmosis

Most clay minerals  have a negatively charged surface
mainly resulting from imperfections in the mineral lattices
developing during formation. The excess negative charge
on the soil surface results in the attraction and cluster of
excess cations to this surface, and the neutrality of charge
in the pore water is maintained by the respective anionic or
cationic concentrations of species away  from the soil
surface. When an electric field is established across the
soil mass, soil pore water cations close to the soil surface
move toward the cathode. The movement of these cations
and any water  molecules closely associated with  these
species will result in pore water flow in the same direction.
This pore  water flow is due to the voltage gradient and is
called electroosmosis. Generally, a wider zone of excess
cations, also known as the diffuse electrical double layer,
results in more  electroosmotic flow.  The double layer is
defined by the  zeta potential, which is the electrostatic
potential on an  imaginary surface near the soil particles.
This surface is defined by zero shear, meaning that water
particles on this surface are stationary. The zeta potential
depends on the magnitude of the charge density on the soil
surface, ionic strength of the pore water, valence of the
cation, pH, and permittivity (the ratio  of electric flux
density  produced by an electric  field  in water to that
produced in vacuum by the same field) of the pore water.

To account for  the tortuosity of ion transport in the soil
pore, the  Helmholtz-Smoluchowski equation (Hunter
1981), which describes the transport of water in an
electrical  field, can  be extended to porous media as
presented  in Equation 1-2.
                            dV
                       VT2 dx
                                             (1-2)
where:

e

c
               electroosmotic velocity (m/s)
               fluid permittivity (Newton-per square
               volt [N/V2])
               zeta potential (V)
                                                        v      =

                                                        T      =
                                                        dV/dx =
               fluid viscosity (Newton-second per
               square meter [N-s/m2])
               tortuosity (dimensionless)
               voltage gradient (V/m)
In general,  electromigration is  the  dominant transport
mechanism for ions in typical soils. As shown in Figure 1-
1, the charge of the ion determines the electromigration
direction in  an electric field, either toward the cathode if
the ion is positively charged or toward the anode if the ion
is negatively charged.  However, because of a negative
zeta potential (the electrostatic potential on an imaginary
surface  near  the  soil  particles)  of  soil  particles,
surrounding jvater has a net positive charge; therefore, the
electroosmosis or bulk water flow is toward the cathode.
Therefore, when a contaminant is anionic, electromigration
of the contaminant ion is counter to the direction of the
electroosmotic water flux.  For  a cationic contaminant,
electromigration and electroosmotic transport are in the
same direction.

By applying, electric current to soil, electrolysis  of pore
water occurs, producing an acid (H+) at the anode and a
base (OH~)  at the cathode,  which could significantly
affects the chemistry of the soil system during treatment.
If no pH conditioning is used at the electrodes, soil could
have a net acidic characteristic at steady state conditions
because the  hydrogen ion has double the mobility of the
hydroxyl ions.

A secondary: effect of current application to soil during
remediation is an increase in temperature because some of
the electrical  energy will be transformed into thermal
energy. This heating may affect the remediation process,
depending  on whether  the electrokinetic  system  is
operated under  constant  current or constant  voltage
conditions. Under constant current conditions, an increase
in pore water temperature will not affect the velocity of
electromigration;  however, electroosmotic velocity will
decrease by 0.4  percent  per degree Celsius.  Under
constant voltage  conditions, each degree  increase in
temperature will increase the electromigration velocity by
3.4 percent and the electroosmotic velocity by 2.1 percent,
and the increase in temperature will decrease the viscosity
of water, thereby also increasing the electroosmotic
velocity. The increase in transport mechanism velocity
with elevated temperatures results in reduction of the time
required for'; remediation (Mattson and Lindgren 1994;
EPA 1997).  System operation  under constant  voltage
conditions is:therefore preferred.
                                                     11

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Methodologies are not well established for evaluating a
site for electrokinetic remediation or for predicting the
associated cleanup level, remediation time, and cost. The
design problem can be addressed in two stages. First, an
estimate of the total amount of electric current required
must be made. This estimate will depend not only on the
contaminant mass to be removed but also on the efficiency
of current usage (in grams of chromium removed per
ampere-hour) or the transference  number, which itself
depends  primarily  on  the chemical  nature  of  the
contamination. Second, a determination must be made of
how the current will be applied over a given time period
(which will determine the grams of chromium removed
per kilowatt-hour). This determination requires additional
physical   information  about  the  site,  such  as  the
contaminant  plume geometry,  soil  resistivity,   and
expected temperature changes. This information, coupled
with the electrode layout,  determines the voltage  and
electrical power requirements.

1.4.2 SNL ISEE System

The ISEE system developed by SNL applies electrokinetic
technology to unsaturated soil.  The SITE demonstration
of the system took place at the UCAP in Technical Area III
at SNL and targeted the removal of chromate (CrO4")from
an area of chromium-contaminated soil that underlies the
pit. The UCAP measures about 15 by 45 feet and is 10 feet
deep (SNL 1994).

The ISEE system used for the demonstration was housed
in two buildings: a control  trailer and a temporary
structure. The control trailer contained the control panels,
the power supply, and the data logging  system.   The
temporary structure protected electrokinetic technology
equipment and personnel and maintained the operational
exclusion zone required during ISEE system operation.

The ISEE system used for the demonstration shown in
Figure 1-2 consisted of anodes, cathodes, and cold finger
cathodes that made up the electrode system.  Because
cathodes were used only during the first phase of the
demonstration, they are not shown in Figure 1-2.   The
operation of the ISEE system was regulated by four units:
a water control system, a vacuum control system, a power
supply system,  a  monitoring system, and  ancillary
equipment.  Each of these systems is discussed in detail
below.
1.4.2.1 Electrode System

Figure 1-3 shows the electrode layout of the ISEE system
used  during  the SITE  demonstration.   The  system
consisted of an anode row oriented east to west and four
rows of cathodes parallel to the anode row, two rows north
and two rows south of the anode row.   Two types of
cathodes  were  used during the SITE  demonstration:
cathodes similar to the anodes, which will be referred to as
"cathodes,"  and simple design cathodes, which will be
referred to as "cold finger cathodes" (identified as "CF" if
they are  standalone or "CFC" if they  are adjacent to
cathode casings). The treatment zone was determined by
the active portion of these electrodes and extended from 8
to 14 feet below ground  surface (bgs).   The electrode
system's anodes and cathodes and cold finger cathodes are
discussed below.

Anodes and Cathodes

The anodes (Al through A5) and cathodes  (C6 through
CIO)  used   at  UCAP   were   designed  to  combine
electrokinetic  and  lysimeter  technologies.     This
combination was necessary to allow the  operation  of the
system under unsaturated soil conditions.   Lysimeter
technology  hydraulically and  electrically  creates  a
continuum between the  anolyte and the  pore  water,
thereby enabling the extraction of the chromate ions in the
anolyte while the anolyte is held under tension in the
electrode casings through the application of a vacuum.

Anodes and cathodes were installed in  6-inch-diameter
boreholes (see Figure  1-4C). Boreholes were generally
drilled to 20 feet bgs. An approximately  4-inch-thick dry
bentonite plug was installed on top of the borehole sluff,
and cuttings were added to bring the borehole bottom to 15
feet bgs.  The bottom of the borehole was sealed with
bentonite. The electrodes were lowered in  the borehole
and suspended from the ground surface.  A watery slurry
of clean native soil was added to the borehole until at least
6 inches above the top of the ceramic part of the electrode
casing. The annular space above was filled with native soil
cuttings to 1 foot bgs.   Finally, a bentonite plug was
installed to approximately 2 inches bgs and covered to the
ground surface with native soil.  After  installation was
complete, a  vacuum was applied to each electrode to
remove excess water from the slurry.

The  anodes and cathodes  consisted  of  two   main
components: the  electrode casing  and  the  internal
                                                    12

-------
                                                                 El
era
e
Mf
*t>
>-*
&
                                                      •12 feet
cr.
                                                                Anode Water Control System

-------
                 CFC1
                  o-
               CF1 C
      'NT5
               CF6
                           T3
                       NT9
                                  'NTI
    •
   Tl
 CFC3
 -o
 T21

CF3
             CFC4
             -o
NTS • • T4 and T6

       T5«  CF4,
                                                                            T7
                           •NT2
 CFC5
-O
                                                                                                                     n
                                      ) CF5
                                                                                          A5   "NT6
                                                                                       OCFIO
                                                                                       Ocio
                                                   LEGEND
                                                   C6   - Cathode 6
                                                   Al   - Anode 1
                                                   CF1  - Cold finger cathode 1
                                                   CFC1 - Cold finger at cathode 1
                                                   Tl   - Temperature probe 1
                                                   NTI  - Neutron hydroprobe access station 1
                                                   \f A - Test 13 zone of influence

                                                   NOTE
                                                   The area displayed measures 12 by 12 feet.
                                                   Each square measures 3 by 3 feet.
                                                     T16
                                                                             'NTIO
Figure 1-3. ISEE system electrode layout.

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          PVC—»
         Flange
               PVC
             Couple I
                U
        PVC Sump-
    10-inch-
    Diameter
«-PVC Cover

)<«-PVCTop E
-Male Adapter
                          2 inches
                           inch-Diameter
                            PVC Pipe
                        i-PVC
                         Couple
3.5-inch-
Diameter
Ceramic
 Casing  Passive
         Voltage
          Probe
  PVC Couple
                 J> From Power
                      Supply
                                                                                           Cooling
                                                                                           Water
                                                                                             In
                    _Water
                     Level


                    Drive
                  Electrode

                 H«— Temperature
                       Probe
                          PVC Cap
             A) Anode/Cathode
                  Casing
          B) Anode/Cathode
          Internal Assembly
           and Associated
              Exterior
             Monitoring
             Equipment
                                                                         Ground Surface
                                                                      Bentonite
                                                                    Native Soil
                                                                    -6-inch-
                                                                    Diameter
                                                                    Borehole
                                            Native Soil
                                            Slurry Mix
                                           Bentonite
                                                                    Borehole
                                                                      Sluff
                                                     C) Anode/Cathode
                                                          Borehole
                                                          Backfill
                                                                         -*• Cooling Water Out
                                                                           0.75-inch-Diameter
                                                                               PVC Pipe
                                                                           0.375-inch-Diameter
                                                                           Polyethylene Tubing
                                                                            for Chilling Water
    0.5-inch-Diameter
      Copper Pipe


   — PVC Couple

   Water Flow
    Direction
11—0.5-inch-Diameter
I     Copper Pipe

|«— Powdered
      Copper
                                                                                                    Copper Cap
                                                              D) Cold Finger
                                                                Cathode
Figure 1-4, Anode/cathode and cold finger cathode construction cross sections.

-------
assembly. Figure 1-4A illustrates the electrode casing
assembly. The electrode casing consisted of two parts: the
bottom  6 feet  (located from 8 to 14  feet bgs) was
constructed of a porous ceramic material, and the top part
(extending from the ground surface to  8  feet bgs) was
constructed of 3-inch-diameter polyvinyl chloride (PVC)
pipe.    The  top part of the electrode casing was
impermeable and nonconductive.  The ceramic material
had a  pore  size of 3 microns, resulting in bubbling
pressures of 19 to 28 pounds per square inch (psi). High
bubbling pressure material was an important factor in the
construction  of the  electrodes.   Depending on  the
magnitude of the vacuum applied to the electrode casing
and the pore water tension in soil immediately adjacent to
the electrode casing, the pore water could enter the
electrode casing or water present in the casing could be
transferred to the soil.  This innovative  feature of the
electrodes was derived from lysimeter technology. The
design overcame the  difficulty of soil  drying  near the
anodes, thus allowing operation  of the electrokinetic
process in unsaturated soil for much longer periods than if
simple electrodes were implanted in direct contact with the
soil. Soil drying occurs when electric current is applied to
soil between the electrodes, thus causing water flow by
electroosmosis, usually to the cathode.  The SNL ISEE
system design allowed soil moisture to be replenished
through the electrode casing.

The ceramic of the  anode casings was treated with a
surfactant to alter the negative  zeta potential of the
ceramic, thereby preventing electroosmotic movement of
water out of the anodes. After the surface was washed with
a 0.1-molar solution of hydrochloric acid, a 0.01-molar
solution  of hexadecyltrimethylammonium bromide was
purged through the ceramic to form a layer that changed
the effective charge  of  the  surface from negative to
positive.

The internal assembly  of the anodes  and  cathodes
consisted of a  drive electrode (see  Figure  1-4B)
constructed of iridium-coated titanium for the anodes and
of copper for the cathodes.  The drive electrodes were
connected to the power supply system by insulated wire
rated for 600 V DC. Control and monitoring systems also
located  inside  the electrode casing  discussed  in  the
following sections.

Cold Finger Cathodes

The purpose of the cold finger cathodes was twofold: (1) to
function as active bare electrodes to increase the voltage
gradient and (2) to function as heat exchangers in case soil
temperatures become excessive. As shown in Figure 1-3,
16  cold  finger cathodes were  used during the SITE
demonstration of the ISEE system (cold fingers CFC2,
CF2,  CF7, and  CFC7 were not  energized during the
demonstration and do not appear in this figure).

Originally, cold finger cathodes CF1 through CF10 were
constructed of 5-foot-long, 0.75-inch-diameter  copper
piping. The bottom of the pipe was capped with a copper
cap, and the top end was fitted into a 0.75-inch-diameter,
schedule 40 PVC pipe extending to the ground surface. An
insulated copper wire  was soldered to the pipe and was
brought to the ground surface. After September 24, 1996,
to prepare for the final demonstration test, cold finger
cathodes CF1, CF3 through CF6 and CF8 through CF10
were refurbished. The refurbished design (see Figure 1-
4D) consisted of 0.5-inch-diameter copper pipe extending
to the ground surface. This pipe was enclosed by the 0.75-
inch-diameter PVC piping described above and filled with
powdered copper. Inside of the 0.5-inch-diameter copper
piping, a  0.375-inch-diarneter polyethylene tubing was
used to recycle cold water to maintain the cold finger
cathode at a low temperature.

All cold finger cathodes were installed in holes drilled
using the Geoprobe® rig. The diameter of the holes was
1.5 inches, and the depth of installation ranged from 12.5
to 13.6 feet bgs. These holes were filled with soil slurry to
above the metallic part of the electrode. The cold finger
cathodes were installed immediately after soil slurry was
poured into the holes, and remaining space in the hole was
backfilled with native materials. The top of the hole was
plugged with bentonite.

The construction of cold finger cathodes CFC1 through
CFC5 was simple. These cathodes were 6.67 feet long and
constructed  of 1-inch-diameter  copper  pipe.    The
conductive part of the  electrode  was connected to the
bottom of 0.75-inch-diameter PVC piping extending to the
ground surface.

1.4.2.2  Water Control System

Anode and cathode casings were filled with water to about
6 inches above the fitting between the ceramic material
and the PVC pipe.  The water control system consisted of
the water circulation system and the pH control  system,
which are described below.
                                                    16

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 Water Circulation System

 The purposes of the water circulation system were to (1)
 monitor the chemical condition of water in the electrode
 casings, (2) cool water in the electrode casings, (3) provide
 means to sample and remove water from the casings, (4)
 provide means to regulate water pH, (5) mix anolyte in the
 electrode casings, and (6) add potable water (influent) to
 the anode  and cathode casings to compensate for  the
 extraction of effluent.

 The water circulation system  was powered by bladder
 pumps located in each electrode casing (see Figure 1-2).
 The screen portion  of the pump was  located  in  the
 electrode  casing sump.   Because the bladder pumps
 operated in  a  subatmospheric  pressure  environment
 because of vacuum  applied to the head  space  of  the
 electrode,  a liquid  ring  vacuum  pump and an  air
 compressor were  used to activate the pumps.  The
 recirculation flow rate was about 4 liters per minute  (L/
 min).

 Anode and cathode effluent was collected in 55-gallon,
 closed-top polypropylene drums. Catholyte was extracted
 only from  the  cathodes and not from the cold  finger
 cathodes. At 3 0-minute intervals, the effluent controller in
 the control trailer sent a signal to the air-operated, three-
 way-solenoid valve, and recycle flow was redirected to the
 drums instead being returned to the electrode casings. The
 three-way valve was deactivated after a preset amount of
 water measured by the effluent sensor was extracted from
 the system.  Under  normal operating conditions,  the
 amount of water extracted from the system varied from 0.1
 to 0.5 liter per 30 minutes.

 The water level in the electrode casings was maintained
 within a 6-inch interval above the PVC couple joining the
 ceramic and PVC casing sections  using reed-type float
 switches.

 pH Control System

The pH of water in the ISEE system had to be maintained
to ensure proper system operation. High pH values could
result  in   the  precipitation   of  metals  and  hinder
contaminant transport and  removal.  To minimize these
effects, the required pH range for the anolyte was.5.5 to 11,
with an ideal pH of 8.8. The pH range for the catholyte was
3 to 11, with an ideal pH of 5.5.
 The pH of pore water in the treatment area was likely to be
 influenced by the hydrogen and hydroxyl ions produced at
 the electrodes from electrolysis. Consequently, the pH of
 the recycled iwater was closely monitored .and controlled
 for  each  electrode  using  sensors, transmitters, and
 controllers. The pH controller regulated the operation of a
 chemical fefed pump  located on top of  a  55-gallon
 polyethylene drum containing buffer fluid.  A  10 percent
 sodium hydroxide solution was used to control the anolyte
 pH, and a 20 percent acetic acid solution was used to
 control catholyte pH.

 1.4.2.3  Vacuum Control  System

 As stated earlier in this section, the SNL ISEE system uses
 lysimeter technology to control the amount of  water
 delivered to the unsaturated zone.  An air compressor
 provided the Compressed air necessary for the operation of
 the vacuum pumps (see Figure 1-2). Compressed air was
 driven through a series of Venturis within the vacuum
 pumps, causing additional air to be drawn through the
 venturi system. An added feature of the system was the
 ability to purge hydrogen gas produced by electrolysis
 from electrode casing headspace thus eliminating the
 danger of explosion.

 Vacuum in the cathode  casings was  created by  three
 vacuum ejector pumps installed in parallel. Vacuum in the
 anode casings was created using four vacuum ejector
 pumps installed in parallel. Rather than directly regulating
 the vacuum applied to the electrodes, vacuum regulators
 allowed air to enter the electrodes and dilute oxygen and
 hydrogen gasps in the electrode headspace. The regulators
 were generally maintained at a vacuum of 14 inches of
 mercury for both the anodes and cathodes.

 The minimum air purge necessary to maintain hydrogen at
 the lower explosive limit in  the anode casings was
 estimated to b,e 3.3 L/min. The system alarm was set to 3.5
L/min for added safety, and the purge rate was set for 8 L/
 min to ensure,that the hydrogen level was maintained well
 below the explosive limit. Air was also purged through the
 cathode casings at 2 L/min to dilute oxygen produced by
 electrolysis, i

 1.4.2.4 Power Supply System

The ISEE system electrodes were energized using four 10
kilowatt (kW) power supply units. Each unit was capable
                                                   17

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of a maximum output of 16 amperes (amp) at 600 V DC.
Each  unit was operated independently under constant
voltage conditions.

The power units were located in the control trailer, and
electric current was delivered to the  electrodes by
underground cables protected by 3-inch-diameter electrical
conduits. Both parallel-and independent-type connections
were equipped with a main manual disconnector that cut
off power while the system was not in operation.  The
current delivered to each electrode was limited to 15 amps
by an in-line fuse and was monitored using an  isolated
current transmitter by measuring the voltage drop across a
20 amp per 100 millivolt shunt.  Transmitter output was
processed to determine the current, which was displayed
on a control panel and recorded by a data logger.

1.4.2.5 Monitoring System

The  operating parameters of  the ISEE system were
displayed on the control panel and recorded by a data
                logger.    Table  1-2  summarizes monitoring  system
                parameters.  The parameters monitored were measured at
                1-minute intervals, averaged and were recorded over 60-
                minute intervals. The monitoring system could shut down
                the ISEE system  and send a  problem-specific coded
                message by cellular telephone  to two operators if any
                monitored parameters were out of preset tolerance limits.

                In addition, when the system was energized, access to the
                exclusion zone was not permitted. Thus, entrance to the
                temporary structure was monitored using a simple switch
                to ensure that the entry door to the temporary structure was
                closed.    Also,  effluent  barrels  and  their secondary
                containment were equipped with overflow switches that
                could signal system shutdown.

                The shutdown system could cut off the  power to the
                electrodes,  close  influent  water valves, de-energize
                influent and  effluent  solenoids, and  discontinue the
                pumping of pH control solutions. Depending on the type
                of alarm that triggered the shutdown, recycle of electrode
                water through the recycle board  could also be terminated.
Table 1-2. Monitoring System Parameters
             Parameter Measured
Support System
Automatic Shutdown Limit
             Air purge rate
             Vacuum level
              Electrode casing water
              level

              Recycle flow
              Influent and effluent rates

              Conductivity

              Recycle flow temperature

              PH


              Soil temperature
              Voltage in soil
Vacuum control
system
Vacuum control
system

Water control
system

Water control
system

Water control
system

Water control
system
Water control
system
Water control
system

Ancillary equipment

Ancillary equipment
Below 3.5 L/min for cathodes only

Below 1.47 psi

More than 6 inches above or below the
water level control floats

No recycle flow

None

None

Above 60°C

For cathodes less than 3 and greater
than 11, and for anodes less than 5.5
and greater than 11

Above 60°C

Step potential of 10V
                                                     18

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1.4.2.6 Ancillary Equipment

To monitor and control the operation of the ISEE system,
SNL   installed  ancillary  equipment  that  provided
information on the state  of system operation  or that
provided access to the treated media to influence local soil
conditions  (such  as devices that altered soil moisture
content).  Ancillary equipment included soil moisture
content control devices, neutron hydroprobe and radio
imaging probe tubes, temperature probes, and passive
voltage probes. This equipment is discussed below.

Soil Moisture Content Control Devices

Unsaturated soil  conditions  were  maintained at the
demonstration site throughout the operation of the ISEE
system.  Soil  moisture  control infiltration wells were
installed to add water to the soil, if desired. Infiltration
wells increased soil moisture content.   Fourteen  wells
were used prior to the operation of the system under SNL's
preferred operating conditions to add moisture to soil.
These wells were constructed of 0.5-inch-diameter PVC
piping 11 to 13 feet long.  Approximately 20 slots were
made in the bottom 9 to 12 inches of the PVC pipe, and the
bottom of the pipe was sealed with a PVC plug.  These
wells were installed in 1.5-inch-diameter boreholes drilled
using the Geoprobe®  rig.  The annular space was  filled
with 10/20 silica sand in the area of the screen interval and
with dry, granular bentonite above this interval.

Neutron Hydroprobe and Radio Imaging  Probe
Tubes

Neutron  hydroprobe  measurements  of soil  moisture
content were taken on a weekly basis using 10 access tubes
(see Figure 1-3). Most of the tubes were installed to 39 to
41 feet bgs, and one tube was installed to 31 feet bgs. The
tubes were installed in 7-inch-diameter boreholes drilled
using a hollow stem auger.  The annular space was  filled
using drill cuttings, and the holes were plugged at the top
with dry bentonite.  The tubes were constructed of 2.5-
inch-diameter, threaded PVC piping.  The diameter was
selected to allow access of radio imaging probes used to
determine vertical conductivity profiles of soil beneath the
UCAP.

Temperature Probes

A total  of 32 temperature probes were installed at the
demonstration site (see  Figure 1-2).  The temperature
probes were  located  generally at 11 feet bgs in the
treatment zone. Sixteen of the probes (not shown in Figure
1-3) were installed on electrode casings at the PVC couple
between the two ceramic pieces that make up the electrode
casings and 16 were installed between the electrodes as
shown in Figure 1-3.

Passive Voltage Probes

Passive voltage probes were used to generate data needed
to prepare electrical potential maps of the demonstration
site. Twenty passive voltage probes were located on the
electrode  casings,  and   another  12  were installed
throughout tfte demonstration site. These probes consisted
of 50-mesh stainless steel screen squares with an area of
about 2 square inches attached to insulated wires that
reached the ground surface.  The pieces of mesh were
attached to 0.75-inch-diameter PVC pipe at a depth of
about  10  feet  bgs.  Probes were installed  using  the
Geoprobe® rig.

1.4.3  Innovative Features of the
        Technology

Metals-contaminated soil can be treated either in situ or ex
situ. Common methods for treating soil in  situ include
stabilization/solidification  and vitrification.  Promising
results were 'obtained during testing of other innovative
treatment technologies such as soil flushing.  The most
common ex situ treatment technology is  soil washing.

Treatment  of  soil hi situ using  electrical separation/
electrokinetic removal under saturated soil conditions has
been tested by several vendors. However, the ISEE system
designed  by  SNL  focuses  on  the  remediation of
unsaturated soil instead of saturated soil.

The innovative feature of the ISEE system is that lysimeter
technology is used in the construction of the anodes and
cathodes toi hydraulically and electrically  create a
continuum between the electrolyte and the  pore water.
The electrode  fluid is held inside the  electrode by an
applied vacuum, keeping the fluid from saturating soil.
This feature allowed the removal  of  chromate  from
unsaturated  soil  during  the  demonstration without
significantly altering the  soil moisture content.   The
vacuum control system maintains the vacuum in the anode
electrode, which creates the pressure gradient between the
anode's porous ceramic casing and the surrounding soil
necessary  to  hydraulically  control  water movement
between the anode casing and the soil.
                                                    19

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The  ISEE  system  developed  by  SNL presents  the
advantage that the structure, volume,  and makeup of
treated  soils are  not  significantly affected  by  the
application of the  technology as is  the case with
remediation by stabilization/solidification, vitrification,
or chemical treatment. The moisture content of the soil is
maintained at levels below saturation, which is not the case
with soil flushing or chemical  treatment because these
technologies use  water as  the transport medium  for
treatment additives.  Table 1-3  compares several in  situ
treatment options for soil contaminated with heavy metals.

1.5    Applicable Wastes

The ISEE technology developed by SNL is applicable for
treating unsaturated soil contaminated  with hexavalent
chromium. According to SNL, this technology can be
modified to treat saturated contaminated soil and to
remove contaminants  dissolved in pore water besides
chromate. Because other anions will compete  with the
targeted contaminant ions to be removed, it is necessary to
determine the electrical conductivity of soil pore water and
the target ion concentration to determine the applicability
of the ISEE technology.

1.6    Key Contacts

Additional information about the ISEE system and the
SITE program can be obtained from the following sources:

SNL ISEE System
Dr. Eric R. Lindgren
Sandia National Laboratories
Dept.6621,MS0719
P.O. Box 5800
Albuquerque, NM 87185-0719
Telephone No.: (505) 844-3820
Fax No.: (505) 844-0543
E-mail Address:  erlmdg@sandia.gov

The SITE Program
Mr. Randy Parker
Office of Research and Development
U.S. Environmental Protection  Agency
26 West Martin Luther King Drive
Cincinnati, OH 45268
Telephone No.: (513) 569-7271
 Fax No.: (513) 569-7571
 E-mail address: parker.randy@epamail.epa.gov
Information on the SITE program is available through the
following on-line information clearinghouse: the Vendor
Information System for Innovative Treatment Technologies
(VISITT)  (Hotline:  800-245-4505) database contains
information on 154 technologies offered by 97 developers.

Technical  reports may be obtained by contacting U.  S.
EPA/NSCEP, P. O. Box 42419, Cincinnati, Ohio 45242-
2419, or by calling 800-490-9198.
                                                   20

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Table 1-3. Comparison of In Situ Treatment Technologies for Metals-Contaminated Soili
             Technology
         Advantage
             Disadvantage
       SNL In Situ Electrokinetic
       Extraction System
       Stabilization/Solidification
      Vitrification
      Soil Flushing
 Maintain unsaturated soil
 conditions; soil makeup not
 significantly affected
Applicable to wide range of
soils because of flexibility in
design of appropriate
additives and use of a large
variety of mixing techniques;
some organic compounds
can be incorporated in the
solidified matrix; relatively
low cost

Applicable to complex
wastes (combination of
metals and organics, .
including mixed wastes); also
applicable to
nonhomogeneous soils
containing buried containers
(however, under some
conditions, metal objects
could short-circuit the current
path); relatively moderate
cost

Applicable to soils containing
organic and  inorganic
wastes; relatively low cost
 Currently tested for the removal of
 chrornate from unsaturated soil only;
 requires disposal of liquid waste
 containing hexavalent chromium as
 hazardous waste; volatile organic
 comppunds (VOC) may be stripped
 from soil and increase soil vapor
 concentrations and contaminant
 migration; relatively high cost; no
 commercial-scale system available

 Long-term reliability not well known;
 considerably increases volume of
 waste; leachate from curing process
 may need to be collected and disposed
 of as hazardous waste
High soil moisture content limits
applicability; off-gases (VOCs,
combustion gases, and steam) need to
be collected; presence of buried
materials could start underground fire;
soil characteristics dramatically changed
by application of the technology;
decrease in volume of soil
Not applicable to soil with low
permeability; migration of contaminants
to deeper zones possible from
increased mobility if no controls exist
(for example, a clay layer); soil moisture
content increases; requires treatment of
water recovered after flushing
                                                     21

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                                            Section 2
               Technology Effectiveness and Application Analysis
Tilts section addresses the effectiveness and applicability
of the ISEE system  designed  by SNL  for  treating
unsaturated soil contaminated with hexavalent chromium
in the form of chromate.  Vendor claims regarding the
effectiveness and applicability of the ISEE system are
included  in the appendix.  The evaluation of the ISEE
system's effectiveness and potential applicability is based
mainly on the demonstration results presented in this
section. This section provides an overview of the ISEE
system   SITE  demonstration   and  discusses  SITE
demonstration results, factors affecting performance, site
characteristics  and  support  requirements,   material
handling  requirements, technology limitations, potential
regulatory  requirements,  and  state  and  community
acceptance.

2.1    Overview of ISEE System SITE
       Demonstration

The ISEE system SITE demonstration took place at the
UCAP, which is part of the CWL site located within
Technical Area III at SNL. The UCAP is a rectangular pit
measuring about 15 by 45 feet and is 10 feet deep. The
areal  extent  and  depth of the  area targeted  by the
demonstration was selected based on the highest results of
water soluble chromium concentrations from sampling
performed during previous investigations  (SNL  1994).
During the demonstration, the system was operated for a
period of 2,127 hours between May 15 and November 24,
 1997.  The area of the demonstration ranged from 36 to
72  square feet and targeted contaminated soil located
between  8 and 14 feet bgs. The configuration of ISEE
system electrodes is presented in Figure 1-3.

The CWL site was used by SNL for chemical disposal
from 1962 to 1985.  During this time,  chemicals were
separated by type and disposed  of in separate trenches.
Over 4,290 gallons of chromic sulfuric acid solution was
disposed  in  the  UCAP  (SNL  1997).     During
predemonstration sampling activities, a few soil samples
exhibited high moisture content and pieces of glass plastic
were  present  in the samples,  suggesting that the
Geoprobe®  sampler  penetrated  chemical  disposal
containers that have maintained their integrity.

Project objectives, the SITE demonstration approach, and
sampling and analytical procedures are discussed below.

2.1.1 Project Objectives

Project  objectives  were  developed based  on EPA's
understanding  of the SNL  ISEE technology,  SITE
demonstration  program  goals,  and  input  from the
technology developer and the State of New Mexico. The
SITE demonstration had one primary objective and two
secondary objectives.   The  primary objective was
considered  critical  for  the  technology   evaluation.
Secondary objectives involved collection of additional
data that were useful but  not critical to the technology
evaluation.   The primary objective of the  technology
demonstration was to estimate the amount of hexavalent
chromium removed from soil by the ISEE system because
the  ISEE system  is primarily  designed  to  remove
hexavalent chromium. To accomplish this objective, SNL
collected and analyzed anolyte samples for hexavalent
chromium  at  its  field   laboratory  throughout  the
demonstration period. An independent check of field
analytical data was provided by EPA through split sample
analysis at an off-site laboratory.  Field analytical data
were subsequently  deemed  adequate to estimate the
amount of hexavalent chromium removed from soil by the
ISEE system.  Predemonstration and postdemonstration
soil  samples  collected  by  EPA were  analyzed for
hexavalent chromium to verify the hexavalent chromium
removal estimate based on anolyte sample analysis.
                                                   22

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The secondary objectives of the technology demonstration
were to determine whether treated soil meets the toxicity
characteristic leaching  procedure  (TCLP) regulatory
criterion for chromium and to evaluate the ISEE system's
ability to remove trivalent chromium from site soil.

To conduct the demonstration, SNL was required to meet
the conditions  of  the  New  Mexico  Environmental
Department's Resource Conservation and Recovery Act
(RCRA)  Research,  Development,  and Demonstration
permit for the ISEE system.  Predemonstration testing
results indicated that some of the soil in the demonstration
area is hazardous (EPA  waste code D007) because
chromium concentrations exceeded the TCLP criterion for
chromium.   Therefore, the permit required  that SNL
perform postdemonstration TCLP testing to determine the
impact  of  the  ISEE system  on  soil known  to  be
contaminated. SNL therefore collected a large number of
treated soil samples  for total chromium analysis after
extraction using TCLP.

Because incidental removal of trivalent chromium will
likely be accomplished by the ISEE system, evaluation of
trivalent  chromium  removal was  a secondary project
objective of this project. To accomplish this objective, the
predemonstration  and postdemonstration  soil samples
collected for hexavalent chromium analysis were also
analyzed for total   chromium  so that the  trivalent
chromium concentrations  could be calculated as the
difference between the total and hexavalent chromium
concentrations.

2.1.2 Demonstration Approach

The ISEE system SITE demonstration system operation
and test plan is detailed in SNL's demonstration plan (SNL
1997).  This section summarizes SNL's demonstration
plan.   During  the SITE demonstration, 13 tests were
performed during six phases.  The test areas ranged from
36 to 72 square feet, and contaminated soil from 8 to 14
feet bgs was treated.  The first 12 tests were conducted so
that  SNL  could  determine  the  preferred  operating
conditions for Test 13 and to facilitate the migration of
hexavalent chromium toward the central portion of the test
area.  Test  13 consisted of system performance testing
under SNL's preferred operating conditions for the SITE
demonstration.  Table 2-1 summarizes  key conditions
during the 13 tests.
During Phase 1, six tests were conducted in the southern
half of the test grid between the anode row and C6 through
CIO.   During these tests,  SNL  identified inefficient
electrodes (A2 and C7) and adjusted the electrical current,
electrical power level, and anolyte extraction rate.

During Phase 2, three tests were conducted in the northern
half of the test grid between the anode row and CFC1
through CFC5.  During these tests, SNL  used  the less
expensive cold finger cathodes; adjusted  the electrical
current, electrical power level, and anolyte extraction rate;
and operated the infiltration wells to facilitate hexavalent
chromium migration toward the middle portion of the test
grid.       ;

During Phase 3, one test was conducted in the southern
portion of the northern half of the test grid between the
anode row and CF1 through CF5. SNL set the operating
conditions for this test based on results from Phases 1 and
2.         :

During Phase 4, one test was conducted in the southern
half of the  test grid between the anode row and CFC6
through CFC10. This test was intended to be a replicate of
Test 6  during  Phase  1 and was conducted to fill
information gaps identified for Test 6.

During Phase 5, one test was conducted in the northern
portion of the southern half of the test grid between the
anode row and CF6 through CF10.  SNL set the operating
conditions for this test based on results from Phases 1, 2,
and 3.      i

During Phase 6, one definitive test was conducted in the
middle portion of the test grid between CF1 through CF5
and CF6 through CF 10. SNL set the operating conditions
for this test based on results from Phases 1, 2, 3, and 5.
SNL identified Phase 6 (Test 13) conditions as the ISEE
system's  preferred  operating conditions.   Operating
conditions during Test 13 are summarized in Table 2-2.
SNL operated the ISEE system at the preferred conditions
to evaluate system performance and treatment costs.

2.1.3 Sampling and Analytical
       Procedures

Three sampling events occurred during the ISEE system
SITE  demonstration: predemonstration soil sampling,
anolyte (electrolyte from the anodes) sampling during the
                                                   23

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       Table 2-1. Test Matrix for SNLISEE System Demonstration
to
Phase Test Area
1 Southern Half Anode Row and C6
through C10




2 Northern Half Anode Row and CFC1
through CFC5


3 Southern Portion of Northern Half
Anode Row and CF1 through CF5
4 Southern Half Anode Row and CFC6
through CFC10
5 Northern Portion of Southern Half
Anode Row and CF6 through CF10
6 Middle Portion (CF1 through CF5 and
CF6 through CF10)
Test
No.
1
2
3
4
5
6
7
8
g
10
11
12
13
Anodes Used
A1,A2,A3,A4, and AS
A1,A3,A4,andA5
A1, A3, A4, andAS
A1, A3, A4, andAS
A1, A3, A4, andAS
A1,A3,A4,andA5
A1, A3, A4, andAS
A1, A3, A4, andAS
A1.A3, A4, andAS
A1, A3, A4, andAS
A1.A3, A4,andA5
A1, A3, A4, andAS
A1, A3, A4, andAS
Average Current1
Cathodes Used (amp)
C6, C7, C8, C9, and C10
C6, C7, C8, C9, C10
C6, C8, C9, and C10
C6, C8, C9, and C10
C6, C8, C9, and C10
C6, C8, C9, and C10
CFC1.CFC3, CFC4, and
CFC5
CFC1.CFC3, CFC4, and
CFC5
CFC1.CFC3, CFC4, and
CFC5
CF1.CF3, CF4, andCFS
CFC6, C8, CFC9, and CFC10
CF6, CF8, CF9, andCF10
CF1, CF3 through CF6, and
CF8 through CF10
19.45±1.68
21.09±2.07
20.08±1.41
34.25±6.98
42.15±2.38
41.07±2.55
29.27±3.48
20.94±2.10
20.79±1.21
30.31 ±3.78
33.49±1.87
39.31 ±3.64
35.92±4.71
Average Power1
(kW)
1.30±0.11
1.68±0.18
1.77±0.15
4.65±0.94
5.76±0.30
4.56±0.31
4.14±0.56
1.90±0.21
1.87±0.11
2.70±0.36
2.38±0.15
2.86±0.29
2.10±0.31
Average Anoly te
Extraction Rate11 Test Duration
(L/hour) (hour)
0.440±0.075
0.870*0.542
0.879±0.633
2.026±0.904
3.54
3.957±0.924
3.404±0.263
0.376±0.103
0.723±0.554
0.510±0.046
0.50
0.848±0.693
0.662±0.394
106
368
283
244
34
181
75
89
333
176
20
111
707
            Notes:
            amp   =  Ampere
            kW    =  Kilowatt
            L/hour    =   Liter per hour
            a   Average ± standard deviation of hourly readings for all anodes used in the test
            b   Average ± standard deviation of daily readings for all anodes used in the test; only average presented when fewer than three values
                available

-------
 Table 2-2. SNLISEE System Preferred Operating Conditions


Average
Average
Average
(L/hour)
Oper
Parameter A1 A3
Current (A) 9.9 7.3
Power (kW) 0.40 0.50
Effluent Extraction Rate 0.25 0.25

ating Conditions
A4 A5
8.2 10.3
0.54 0.67
0.20 0.22

 demonstration, and  postdemonstration  soil sampling.
 From  December 1995  through February  1996,  SNL
 collected predemonstration soil samples from various
 depth in boreholes within and near the test areas using a 1 -
 inch-diameter by 24-inch-long Geoprobe® Large  Bore
 Sampler. SNL extracted a portion of each sample with
 water and analyzed the extract for chromium. Additional
 sample portions were sent to the Quanterra Environmental
 Services,  Inc.  (Quanterra),  laboratory  in  Arvada,
 Colorado.  Quanterra extracted these soil samples  by
 TCLP, SW-846 Method 1311, and analyzed the extracts
 for total chromium by inductively coupled plasma (ICP)
 analysis using SW-846  Method 601OA.  TCLP extract
 results are included in Appendix A of the TER.

 In July 1996, EPA selected certain of these soil samples for
 Quanterra  analysis  to  provide  information  on  the
 concentrations of total  chromium  and  of hexavalent
 chromium throughout the test area.  More samples from
 more contaminated areas as determined by SNL's TCLP
 results were selected because these areas are of major
 concern.   To  maximize extraction  of  hexavalent
 chromium, Quanterra dried these soil samples and ground
 them in a  ceramic-lined ring  and  puck mill until the
 samples  could pass through a No. 42 mesh sieve.  A
 preliminary study found that use of an ordinary steel ring
 mill  to  grind   samples  resulted  in  unacceptable
 contamination of the  samples  with chromium  derived
 from mill  material.    "Grinder blanks,"  clean  sand
 subjected to the pretreatment and  analysis, and "sand
 blanks," sand sent directly for analysis, were analyzed to
monitor for such problems.

 Quanterra prepared portions of the sieved soil samples by
 acid digestion using SW-846 Method 3050A and analyzed
them for total chromium using  SW-846 Method 6010A.
Quanterra also prepared other portions of the sieved soil
samples  by  alkaline   digestion  using  SW-846
 Method 3 060A.  These alkaline-digested samples were
 analyzed for hexavalent chromium by colorimetry using
 SW-846  Method  7196A.     These  analyses   were
 accompanied by analysis of the usual QC samples (method
 blanks, matrix spikes, blank spikes, duplicates, and so on)
 to ensure that results were acceptable for use in meeting
 project objectives. The results of these QC analyses are
 included in Appendix B of the TER.

 During operation of the ISEE system,  SNL  collected
 anolyte saniples daily and analyzed them for hexavalent
 chromium to determine removal.  To verify these results,
 EPA obtain'ed anolyte  samples from  all four operating
 anodes daily for 8 days. These samples were all sent to
 Quanterra for analysis for hexavalent chromium by SW-
 846 Method 7196A.  The relative percent differences
 between the |SNL and Quanterra results varied from 0 to 20
 percent

 After the demonstration, EPA collected soil samples using
 the Geoprobe® from locations near (within 1 foot laterally
 and 2 inches vertically) from the sampling locations and
 sent these samples  to  Quanterra for  the same sort of
 preparation and analyses for hexavalent chromium and
 total  chromium  conducted  during  predemonstration
 sampling.  SNL collected a separate series of Geoprobe®
 samples and sent them to Quanterra for TCLP extraction
 and chromium analysis.  All Quanterra and corresponding
 SNL results are included in Appendix A of the TER.

 2.2    SITE  Demonstration Results

This section summarizes ISEE system SITE demonstration
results  and  discusses  its effectiveness in removing
chromate  from contaminated  soil.    This  section is
organized according to  the project objectives stated in
Section 2.1.1. Estimated treatment costs are discussed in
Section 3.0. .
                                                   25

-------
2.2.1 Removal of Hexavalent Chromium
       from Site Soil

The  primary  objective  of the ISEE  system SITE
demonstration was to estimate the amount of hexavalent
chromium removed from soil by the system. The mass of
hexavalent chromium removed was to be determined from
the amount of hexavalent chromium in the anolyte.  In
general, SNL performed daily sampling and analysis of
the anolyte throughout the demonstration. For each test,
SNL  anolyte results were used to  determine  the total
amount of  hexayalent  chromium  removed  and  the
system's overall removal rate and  removal efficiency.
These results are summarized in Table 2-3.

As mentioned before, 13 tests  were performed in  six
phases during the demonstration.   The first  12 tests,
performed between May 15 and October 18,  1996, were
used  by  SNL to  determine the  system's  preferred
operating conditions. Test 13 was performed between
October 21 and November 24,1996, to determine system
performance and operating costs.

Approximately 520 grams (g) of hexavalent chromium
were removed during the entire demonstration. Overall
hexavalent chromium removal rates varied from 0.074
gram per hour (g/hour) during Test 1  to 0.338 g/hour
during Test 5.  Overall hexavalent chromium removal
efficiencies varied from 0.03 59 gram per kilowatt-hour (g/
kW-h) during Test 7 to 0.136 g/kW-h during Test 13.
 Downtime during system operation ranged from 0 percent
during Test 11 to 66 percent during  Test 1.

 Test 13 results showed increased efficiency of hexavalent
 chromium removal compared to previous test results.  The
 system configuration during Test 13 was representative of
 the configuration of a full-scale remediation system, with
 cold finger cathodes placed symmetrically outward from a
 central anode row. Consequently, a more detailed analysis
 was  performed for Test 13 to determine the hexavalent
 chromium removal efficiency and rate of each electrode in
 addition to overall system performance.  The data set used
 for this analysis was culled from Test 13 data to eliminate
 data points not representative of the system performance.
 For example, data points not representative of steady-state
 operation of the system, such as during the pumping out of
 electrode effluent,  were eliminated, as were data points
 measured within 6 hours or less because the system was
 shut off for some  reason and had to be restarted  after
 servicing. The hexavalent chromium removal efficiency
of each electrode  is  shown  in  Figure  2-1,  and the
hexavalent chromium removal rate of each electrode is
shown in Figure 2-2.

After data  outliers  were  eliminated,   the  average
hexavalent chromium removal efficiency for anode 4 was
approximately 0.189  g/kW-h, which is  considerably
higher than the average removal efficiencies for the other
three anodes (anodes 1,3, and 5), which ranged from about
0.087 to about 0.111  g/kW-h.  Hexavalent chromium
removal rates were low for anodes 1  and 3 (0.040 and
0.057 g/hour, respectively) and higher for anodes 4 and 5
(0.110 and 0.079 g/hour respectively).

Verification of the total mass of hexavalent chromium
extracted by the ISEE system was supposed to be provided
by the difference between average hexavalent chromium
concentrations in soil before and after the demonstration.
Figure 2-3 presents the spatial distribution of hexavalent
chromium concentrations at the  2-foot depth intervals
characterized by the samples collected before and after the
demonstration.  These results can be summarized as
follows:

  •   Predemonstration   samples  contained  hexavalent
     chromium concentrations ranging from below the
     detection limit of 0.4 milligram per kilogram (mg/kg)
     to 6,890 mg/kg.

  •   Postdemonstration samples  contained  hexavalent
     chromium concentrations from below the detection
     limit of 0.4 mg/kg to 4,730 mg/kg.

  •   Of the 48 locations sampled both before and after the
     demonstration,    21    locations   contained
     postdemonstration hexavalent chromium  concen-
     trations   that  exceeded  predemonstration
     concentrations.

 Predemonstration   and  postdemonstration  hexavalent
 chromium concentrations in soil and their distributions
 were not suitable for any method of calculation of the total
 mass of hexavalent  chromium  in  soil.   A  statistical
 summary of analytical results for hexavalent and total
 chromium is presented  in  Table 2-4.   No  trend was
 identified in the removal of hexavalent chromium from
 soil.  In many cases, the standard derivation exceeded
 average concentrations.   Soil  results  for  hexavalent
 chromium  possibly  exhibited high spatial  variability
 resulting from (l)the nonhomogeneous  distribution  of
  chromate concentrations in soil before the demonstration
                                                    26

-------
       Table 2-3. SNLISEE System Performance Data
to
Phase
Ho.
1





2


3
4
5
6
Notes:
Test Average Power Energy Applied Hexavalent
Test Duration Applied to the to the System Chromium Mass
No. (hour) System (kW) (kW-h) Removed (g)b
1 106/312
2 368/695
3 283/618
4 244/410
5 34/64"
6 181/206
7 75/9CT
8 89/92a
9 333/511
10 176/222
11 20/20"
12 111/163
13 707/831

a 1.30
a 1.68
1.77
4.65
5.76
4.56
4.14
1.90
1.87
2.70
2.38
a 2.86
2.10

138.1
619.9
490.6
1,143.4
195.7
821.2
310.5
168.8
622.1
477.0
50.1
317.5
1,494.3

g = Gram
g/hour = Gram per hour
g/kW-h= Gram per kilowatt-hour
kW = Kilowatt
kW-h = Kilowatt-hour
a Time period for which the system was operational/total test duration
b Hexavalent chromium mass removed was estimated by multiplying the
7.84
35.73
22.54
56.02
11.49
38.24
11.14
9.01
58.66
35.97
4.71
25.45
203.73

volume of ana
Hexavalent
Hexavalent Chromium Chromium Removal
Removal Rate (g/hour) Efficiency (g/kW-h)
0.074
0.097
0.079
0.230
0.338
0.211
0.149
0.101
0.176
0.204
0.236
0.229
0.288

lyte extracted with the concentration
0.0568
0.0576
0.0459
0.0490
0.0584
0.0466
0.0359
0.0534
0.0940
0.0754
0.0940
0.0809
0.136

of hexavalent
                 chromium in the analyte. During the entire demonstration, 520.73 g of hexavalent chromium was removed from soil.

-------
                               Anode 1
       0.4
       0.3
     re
     §
       0.1.
                                •       •
          0     100     200     300     400    500    600     700
                             Time (hour)
                                                                                           Anode 3
                                                                    0.4
                                                                 •*?  0.3
                                                                 IS
                                                                 0)  0.1
                                                                                                   • «      •»
                                                                                          «     »»
                                                                       0      100    200    300     400     500     600     700
                                                                                     Time (hour)
        0.4 ,
        0,3
1
                               Anode 4*
          0     100     200     300     XOO     500    600    700
                             Time (hour)
                                                                                            Anode 5
J? 0.3
I
s
r
a 0.2
I
ra
g
| ft1
                                                                                          «       «
                                                                         100     200     300    400    500     800     700
                                                                                      Time (hour)
          *Note:  Anode 4 had a removal efficiency of 0.584 g/kW-h at 628 hours.
Figure 2-1. Hexavalent chromium removal efficiency per electrode for Test 13.
                                                             28

-------
                                  Removal Rate (g/hour)
                                                                        Removal Rate (g/hour)
ffi
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-------
                                    PREDEMONSTRATION
                                                                            POSTDEMONSTRATION
          6 FEET BGS
           8FEETBGS
           10 FEET BGS
           12 FEET BGS

15
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145 •



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0 5 10 15 20
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                                   Location from which both predemonstration and postdemonstration samples collected.
                                 A Location from which only predemonstration sample collected.
                                 • Location from which only postdemonstration sample collected.
                                   Coordinates (0,0) correspond to location of cathode C6.
                                   U = Analyte not detected, value presented is detection limit.
                                   All results in milligrams per kilogram (mg/kg).
Figure 2-3. Spatial distribution of haxavalent chromium concentrations in soil.
                                                             30

-------
                                     PREDEMONSTRATION
                                                                             POSTDEMONSTRATTON
          14 FEET BGS
         16 FEET BGS
         18 FEET BGS
         20 FEET BGS
20 .
15 .
fr-10.
5 .
0.







1,940
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311
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                                * Location from which both predemonstration and postdemonstration samples collected.
                                A Location from which only predemonstration sample collected.
                                • Location from which only postdemonstration sample collected.
                                  Coordinates (0,0) correspond to location of cathode C6.
                                  U = Analyte not detected, value presented is detection limit.
                                  All results in milligi'ams per kilogram (mg/kg).
Figure 2-3. Spatial distribution of hexavalent chromium concentrations in soil (continued).
                                                             31

-------
Table 2-4. Statistical Summary of Hexavalent and Total Chromium Analytical Results
                                                         Sampling Depth
            Parameter
   6 feet bgs
8 feet bgs
10 feet bgs
12 feet bgs
     Hexavalent Chromium
     Number of Data Points
     Average Concentration
     (mg/kg)
     Standard Deviation
     (mg/kg)
     Total Chromium
     Number of Data Points
     Average Concentration
     (mg/kg)
     Standard Deviation
     (mg/kg)
Pretest  Posttest  Pretest  Posttest  Pretest  Posttest  Pretest  Posttest

   2           7      11       14       11       13        9       12
            5.63     371      216    1,682    1,508     496      726

            7.63     620      359    2,326    1,458     438      940
               7      11      14       11      13        9       12
            81.6   1,202    1,843    5,105   6,149    1,319    1,898

            64.5   1,596    1,566    7,686   4,825    1,140    1,733
                                                         Sampling Depth
Parameter
Hexavalent Chromium
Number of Data Points
Average Concentration
(mg/kg)
Standard Deviation
(mg/kg)
Total Chromium
Number of Data Points
Average Concentration
(mg/kg)
Standard Deviation
(mg/kg)
14 feet bgs
Pretest Posttest

2 12
611

1,238


2 12
1,860

3,651

16 feet bgs
Pretest

8
1,227

1,772


8
2,865

4,016

Posttest

9
236

310


9
564

877

18 feet bgs
Pretest

5
534

651


5
1,201

1,582

Posttest

9
53.0

69.0


9
138

193

20 feet bgs .
Pretest Posttest

3 8
24.4

27.5


3 8
65.4

78.3

     Notes:
                Not calculated because data points insufficient to represent treatment area
                                                    32

-------
 and (2) the fact that the demonstration was terminated
 before chromate removal was completed.  In 'addition,
 limited data  appear  to indicate that contaminants had
 likely migrated from areas outside  of and near the
 treatment area (see Figure 2-3).  Thus, a determination of
 the mass of hexavalent chromium removed based on soil
 sampling results was not possible. Total chromium results
 are summarized and discussed in Section 2.2.3.

 2.2.2  Compliance with  TCLP Regulatory
        Criterion for Total Chromium

 In order to meet the RCRA Research, Development, and
 Demonstration permit for the ISEE system (see Section
 2.1.1),  SNL   collected  predemonstration  and
 postdemonstration soil samples and analyzed them for
 total chromium in TCLP leachate. Figure 2-4 presents the
 spatial distribution of TCLP chromium results for soil
 samples  collected before and after the demonstration
 about 8 to 14 feet bgs. The results shown in Figure 2-4
 represent 2-foot depth interval from the referenced depth.
 For example, the 12 feet bgs sample corresponds to soil
 from 12 to 14 feet bgs.

 As shown in Figure 2-4, of the 43 predemonstration soil
 samples analyzed by TCLP, 18 exceeded the TCLP limit
 of 5 milligrams per liter (mg/L) of total chromium at
 concentrations ranging from 5.6 to 103 mg/L,  with a
 median concentration of 15.4 mg/L. Postdemonstration
 results indicate that 18 out of 35 soil samples exceeded the
 TCLP regulatory criterion for chromium at concentrations
 ranging from 6 to 67 mg/L, with a median concentration of
 20.4 mg/L.

 2.2.3 Removal of Trivalent Chromium
       from Site Soil

Trivalent chromium concentrations were to be determined
by calculating the difference between total and .hexavalent
chromium concentrations. Figure 2-5 presents the spatial
distribution  of  total  chromium   concentrations in
predemonstration and postdemonstration soil samples. A
statistical summary of total chromium concentrations in
soil samples is presented in Table 2-4. Total chromium
sampling results can be summarized as follows:

 •  Predemonstration samples contained total chromium
   concentrations ranging from 7.7 to 26,800 mg/kg.
  •  Postdemonstration samples contained total chromium
    concentrations ranging from 8.2 to 16,200 mg/kg.

  •. Of the 48 locations sampled both before and after the
    demonstration,   31    locations    contained
    postdem'onstration trivalent chromium concentrations
    that exceeded predemonstration concentrations.

 In  general,  the  ratio of trivalent to  total  chromium
 concentrations ranged  from  7.6  to  94.9  percent in
 predemonstration samples and from 27.6 to 99.6 percent in
 postdemonstration  samples.   This  large  variability
 precluded the calculation of the trivalent chromium mass
 removed as 'Originally intended because it would have
 further increased the data uncertainty.  The  increase in
 total chromium concentrations at certain locations after
 the demonstration could have resulted from the migration
 of chromium in  the  treatment area in addition to the
 inherent variabilities of the test areas.  Therefore, no
 conclusion was drawn regarding the ISEE system's ability
 to remove trivalent chromium.

 2.2.4 Operating Problems

 The ISEE system's operation was observed  during the
 demonstration, and the problems  and their resolutions
 were recorded by SNL personnel. The demonstration
 lasted over approximately 4,230 hours.

 The system was not operable for 36 percent of the time.
 Table 2-5 presents the reasons for the shutdowns and the
 percentages ;of shutdown times relative to  the entire
 duration of the demonstration. In addition, the system was
 not energized for 3 percent of the tune (approximately  140
 hours) to perform anolyte sampling and soil moisture
 measurements using the neutron hydroprobe.

 2.3   Factors Affecting Performance

Factors affecting performance of the ISEE system include
(1) waste characteristics, (2) operating parameters, and (3)
maintenance requirements.  These factors are discussed
below.

 2.3.1 Waste Characteristics

The ISEE system is applicable to treatment of soil
contaminated with hexavalent chromium under unsaturated
                                                  33

-------
                                PREDEMONSTRATION
                                                                        POSTDEMONSTRATION
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     10FEETBGS
      12 FEET BGS
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0 5 10 15
FEET
15


10
1
W
'
5


n



32.8
14
•

43.9
13.8 •
3.6

II
8,9

1.9



67
0.01 U




0.052J



22.2













0 5 10 15
FEET
                           Bold number indicates that total chromium concentration exceeded TCLP limit of 5 mg/L
                           *.  Location from which both predemonstration and postdemonstration samples collected.
                           A  Location from which only predemonstration samples collected.
                        '   •  Location from which only postdemonstration samples collected.
                           All results presented in milligrams per liter (mg/L)
                           Coordinates (0,0) correspond to the location of cathode C6.


Figure 2-4. Spatial distribution of TCLP teachable chromium concentrations in soil.
                                                            34

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                                    PREDEMONSTRATION
                                                                            POSTDEMONSTRATION
          6 FEET BGS
          8 FEET BGS
         10 FEET BGS
         12 FEET BGS
20
15
t«10 .
E
g
5 .
0 .







259*



125
*






0 5 10 15 20
FEET
•m
15 .
H10 .
5 .
0 ,



i
256

11.8J
•
IZ580
620 I-6*0
«
891
>658

7.7
•
1,150
•
678


5,717
•


0 5 10 15 20
FEET
15 .


(-ID
5 !

0 .



8.81

4,540 824





1,920
8,440
• 3,450
6,550


11.1


26,800






2,3601





"



0 5 10 ' 15 20
FEET
,n
15 .
f-,10 .
s'.
0 ,


•184
4
28.2

1,470
2,990 9"
> 1,060


3,060
A
1,840


242


0 5 10 15 20
FEET
?"
15
H^O .
's\
0 |

I 21
147
132


58 »


8.2
•
ISO
•
125





0 5 10 15 20
FEET
pn
i
15
1 I
H^n
u< !
«'
l
0 ,

I344
3,020 982
I •
2,030

32.2
4/80
»
657
• 685
1,350
1.700

8.6
•
3,720
2,280


4,520


0 5 10 15 20
FEET
?n
15 .
H10 '
5 !
0 1

408
8,340^1,58
5,270

4,470
•
1,760
"•8,790
13,000
> 8,330

12.7
•
16,200
•
5,420


6,350


0 5 10 15 20
FEET
•m
\
15 .

|
H 10 .

is!

'0 ,


660

433 3,480
•
i
1,590



1,390
•
.273
• 3,970
•5,470


11.3
•



3,250
1,450




801
•











0 5 10 15 20
FEET
                                 Location from which both predemonsfration and ppstdemonstration samples collected.
                                 Location from which only predemonstration sample collected.
                                 Location from which only postdemonstration sample collected.
                                 All results in milligrams per kilogram (rag/kg)
                                 Coordinates (0,0) correspond to location of cathode C6.
Figure 2-5. Spatial distribution of total chromium concentrations in soil.
                                                           35

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                                  PREDEMONSTRATION
POSTDEMONSTRATION
        14 FEET BGS
        16FEETBGS
        18 FEET BGS
         20 FEET BGS
20
15 .
(-10 .
1
'*t
S ,
0 .






3.320
»



845
•






0 5 10 15 20
FEET
20
15 ,
[-.10 .
k
5 ,






285
•
1,340
11,900
A.
2,010
5.240

123
•
1,810
»



189
»


0 5 10 15 20
FEET
20
15
(-.10 .

5 !


0
(



3,9201




146


1,100
•792










48.6











J 5 10 15 20
FEET
20
15 .

10

5
0







62.1



• 1,7401









67.6









0 5 10 15 20
FEET
20
15
I
H10
B
s'
0 |

11,230
138.3
1
1,330

710
1,1*0
12,700
»
4,660
147.4

28
•
151
•
78.7


181


0 5 10 15 20
FEET
20
15
1
H10 .
1
I1
0

1223
79.1


240
»
2,640

203
•195


64.2
•
74.1


1,360
*


0 5 10 15 20
FEET'
20
15
1
t_,10
il
5 '
n ,

1 84. 1
•600
15.8

'I9

22.2
•11.8

72.6,

17.6


279
•


0 5 10 15 20
FEET •
20
15

'
ts
iS
i





135.3

1252

15.2
J


75.3


.10.3


58.2
"



43.5



33.5










5 10 15 20
FEET
                               * Location from which both predemonstration and postdemonstration samples collected.
                               A Location from which only predemonstration sample collected.
                               • Location from which only postdemonstration sample collected.
                                 All results in milligrams per liter (mg/kg).
                                 Coordinates (0,0) correspond to location of cathode C6.
Figure 2-5.  Spatial distribution of total chromium concentrations in soil (continued).
                                                          36

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 Table 2-5. System Shutdown Information
Reason for System Shutdown	
Intentional shutdown to perform maintenance and modifications to the system
Problems related to electrode water (such as bladder pumps, float switches, and
chiller leakage)                                               ,
Power supply failures and problems                            •
pH control system problems
Data logger problems                                         ;
                                                                    Total
                                                                                    Percent of System
                                                                                     Shutdown Time
                                                                                           21
                                                                                           7

                                                                                           4
                                                                                           2
                                                                                           2
                                                                                           36
 conditions as demonstrated at the UCAP.  According to
 SNL, the ISEE system is also applicable to treatment of
 soil contaminated with anionic, heavy metals if the metal
 anions are water soluble.  Water soluble anions such as
 CrO4=,  HAsO4=,  and  SeO4=  are  potential   target
 contaminants for the ISEE system.

 The system has no absolute lower concentration limit to
 which it can treat  contaminants  unless  the  system's
 contaminant removal efficiency  indicates otherwise;
 therefore, the system's contaminant removal efficiency
 needs to be determined on a site-by-site basis (Tetra Tech
 1997). According to SNL, the technology is applicable to
 any type of soil  except gravel.  Buried metal objects,
 however, can short circuit the path of electric current
 through the soil (Tetra Tech 1997).

 The presence of dissolved VOCs in general in the pore
 water does not affect system performance. However, the
 application of electric current may transport dissolved
 VOCs through electroosmosis toward the cathode, where
 they could enter the cathode casing. In the casing, vacuum
 applied would strip VOCs from the solution.   These
 emissions need to be collected and treated as necessary.
 According  to   SNL,  during   the  early  stages  of
 demonstration, air monitoring done at the cathode casing
 did not show the presence of VOCs above 150 parts per
 billion. However, the VOC levels significantly increased
 in the soil vapor when the soil temperature was about 50
 °C. The use of cold finger cathodes that do not have an
 exhaust eliminated VOC emissions to atmosphere.

 2.3.2 Operating Parameters

Operating parameters can be varied during the treatment
process  to achieve desired contaminant removal and
                                                 treatment goals. Limited experimental data are currently
                                                 available to define the behavior of the ISEE system used to
                                                 remediate contaminated soils under unsaturated conditions.
                                                 Experimental data are critical because soil electrochemistry
                                                 is complex and because of the nonlinear interdependence
                                                 of the parameters.

                                                 Laboratory testing was performed by SNL to evaluate the
                                                 influence  of  soil  moisture  on  the  efficiency  of
                                                 electrokinetic technology applied to unsaturated  soils
                                                 under constant current conditions.  Experimental results
                                                 on UCAP soil show that near saturation, electromigration
                                                 velocity increases as  soil moisture content decreases.
                                                 However, at lower moisture content, the nonlinear effect
                                                 of tortuosity dominates and the electromigration velocity
                                                 decreases sharply as moisture content decreases. Also, for
                                                 the UCAP soil, experiments show that electromigration
                                                 and thus remediation ceases at a moisture content of 3.5
                                                 percent by weight  because of the  loss of pore water
                                                 connectivity (Lindgren and others 1991).  The minimum
                                                 moisture  content required  for the operation of the
                                                 electrokinetic technology needs to be  determined on a site-
                                                 by-site basis.

                                                 A secondary factor that affects the performance of an
                                                 electrokinetic extraction  system is soil  temperature.
                                                 Thermal effects on  saturated soil were studied at the
                                                 laboratory scale. If the  system is operated under constant
                                                 current conditions, pore water temperature will increase,
                                                 thereby slightly decreasing electroosmotic velocity but
                                                 not affecting electromigration  velocity  (Mattson  and
                                                 Lindgren  1994).    However,  under  constant voltage
                                                 conditions, increased  soil temperature  will  increase
                                                 electromigration velocity, which could result in reduced
                                                 remediation times (Mattson and Lindgren 1994; Krause
                                                 and  Tarman  1995).   However,  during  the  SITE
                                                    37

-------
demonstration of the ISEE system, the tests performed did
not directly  target the  evaluation of  the  system's
performance  based  on  the variation  of  operating
parameters.  Consequently, operating parameter effects
were confounded and could not be dissociated.

2.3.3 Maintenance Requirements

Maintenance of a full-scale ISEE system is estimated to
require 8 hours weekly.  This estimate is based on the
assumption that the design of parts of the system that
caused frequent shutdowns during the SITE demonstration,
such as bladders and float switches, would be modified to
eliminate problems.

2.4   Site Characteristics and Support
       Requirements

Site-specific factors can impact the application of the
ISEE  system.    These  factors should  therefore be
considered before the system is selected for remediation of
a specific site.  Site-specific factors addressed  in this
section include  site  access,  area, and preparation
requirements; climate requirements; utility and  supply
requirements; support system requirements; and personnel
requirements.

 2.4.1  Site Access, Area, and Preparation
        Requirements

The site must be prepared for the mobilization, O&M, and
 demobilization of the  equipment.  Access roads are
 necessary for equipment transport.  The  site must be
 accessible to equipment necessary to install electrodes and
 ancillary equipment, such as Geoprobe® and drill rigs.
 The air space in the equipment installation area must be
 clear of obstacles (such as overhead wires).

 In addition to the treatment area and  corresponding
 exclusion  zone,  enough space should be available  to
 accommodate the control trailer, hazardous waste storage
 area, water tanks, and supply storage. This additional area
 is estimated to require 8,800 square feet.

 2.4.2 Climate Requirements

 The demonstration took place hi Albuquerque, New
  Mexico,  a semi-arid  region.    The  average  winter
  temperature  is  about 50  °F (10 °C),  and  freezing
conditions occur mainly during the night. A temporary
structure was installed during the demonstration to protect
the ISEE system and personnel from the weather and also
to provide an exclusion zone when electrodes were
energized. The data logger, control panels, and analytical
equipment were housed in the control trailer.

If the ISEE system is  used outdoors hi  a cold climate,
provisions should be made for insulating exposed portions
of the water control  system to  prevent freezing.   In
addition, equipment such as chillers should be designed
for outdoor use.

2.4.3  Utility and Supply Requirements
                       i  i                      i
The ISEE system demonstrated at UCAP was powered by
four 10-kW power supply units. The units were capable of
operating independently or in parallel. When connected in
parallel, the maximum output was 64 amps at 600 V DC.
According to SNL, a three-phase, 230-V, 150-kW power
supply is necessary to operate a full-scale ISEE system.

Water is  also necessary to operate the system.  SNL
estimates that for a full-scale system of 30 electrodes, a
quantity of 3 60 L of water per day is required. Water could
be obtained from a permanent source of potable water or
stored in water  tanks on  site.   In addition,  water for
decontamination activities is required as needed.

The monitoring system requires connection to a telephone
 line or cellular telephone to download data to  an off-site
 computer and to transmit signals that the system has been
 shut down to maintenance personnel.

 2.4.4 Support System Requirements

 Several surveys are required to determine if the site is
 appropriate for electrokinetic treatment.  Electromagnetic
 and magnetic surveys are necessary to determine if large
 metallic objects are buried in soil.  These objects could
 short circuit the current in the soil, thus significantly
 decreasing the efficiency of the remediation process. Soil
 conductivity  and soil  moisture are  also  critical to
 application of the electrokinetic technology; therefore,
 surveys to determine these parameters for soil to be treated
 are also required.

 Also, remediation progresses, anolyte containing chromate
  is removed. This effluent stream is a hazardous waste and
  needs to be handled, stored, and disposed of in accordance
  with applicable regulations.
                                                    38

-------
 2.4.5  Personnel Requirements

 Based on the design of the  ISEE system, which can
 transmit system information off site, no personnel are
 required to be present on site for system operation. The
 system is equipped with a CR7 data logger that monitors
 system parameters and can shut down the system (such as
 by cutting off power to the electrodes and terminating the
 water supply).   The data logger consequently sends a
 coded signal to the system operator that identifies the
 problem. Technical service personnel should be available
 on an as-needed basis to remediate any problems.

 Periodic visits to the site are necessary for activities such
 as collection of anolyte samples,  replacement of full
 effluent barrels, addition of sodium  hydroxide to the pH
 control  barrels,  and  soil moisture  measurement  using
 neutron hydroprobes.  The involvement of a chemist or
 technician  is also periodically  required for chromate
 analysis of anolyte samples collected. According to the
 vendor,  maintenance and routine sampling and analysis
 activities for a full-scale system should require the on-site
 presence of a technician for 8 hours a week.

 Before operating the ISEE system at a hazardous waste
 site, the technician  should have  completed training
 requirements under the Occupational Safety arid Health
 Act (OSHA) outlined in Title 29 of the Code of Federal
 Regulations (40 CFR), Part  1910.120,  which covers
 hazardous waste operations and emergency response. The
 operator should also participate in a medical monitoring
 program as specified by OSHA.

 2.5   Material Handling  Requirements

 The only waste stream produced during the remediation of
 soil using the SNL ISEE system is effluent containing
 chromate extracted from the anode  casings, which is a
 hazardous waste. In addition, decontamination activities
 (such as decontamination of the Geoprobe®) could also
 produce hazardous wastes. If the ISEE system is applied
 to soil that contains VOCs, VOCs would be stripped from
the soil matrix because of heating that occurs when current
 is passed through the soil.  Treatment area should be
monitored for VOC air emissions to evaluate If special
 controls are needed.

In addition, a site plan is required to provide for personnel
protection and special handling measures. Wastes need to
be appropriately stored  until sampling results indicate
 their acceptability for disposal or release to a treatment
 facility.

 2.6    Technology Limitations

 Prior to implementing electrokinetic remediation at  a
 specific site, field and laboratory screening tests should be
 conducted to determine if the site is amenable to this
 technology.  Field conductivity surveys are necessary to
 determine the soil's electrical conductivity.  Also, buried
 metallic objects  and utility lines could short circuit the
 current path,; thereby influencing the voltage gradient and
 affecting the contaminant extraction rate. Electromagnetic
 surveys should be conducted to determine the presence of
 buried metallic objects.

 In addition, if VOCs  are present in soil  undergoing
 electrokinetic treatment, the VOCs may be stripped from
 the soil to significantly increase the soil  vapor VOC
 concentrations that  would  result in significant VOC
 migration from the treatment area, if soil temperature
 exceeds 50 PC.  Special measures therefore need to be
 taken to contain and control VOC emissions.

 2.7     Potential Regulatory Requirements

 This section discusses regulatory requirements relevant to
 use of the ISEE  system at Superfund RCRA corrective
 action sites.  Regulations applicable to implementation of
 this system depend on site-specific remediation logistics
 and the type of contaminated soil being treated; therefore,
 this section presents a general overview of the types of
 federal  regulations  that may apply  under  various
 conditions. State requirements should also be considered,
 but because these requirements vary from state to state,
 they are not discussed in detail in this section. Table 2-6
 summarizes  ;the  regulations  discussed below.   These
 regulations include the Comprehensive Environmental
 Response, Compensation, and Liability Act (CERCLA);
 RCRA; the  Clean Air Act (CAA); Toxic  Substances
 Control Act'(TSCA);  Atomic Energy Act (AEA) and
RCRA for mixed wastes; and OSHA requirements.

 2.7.1  Comprehensive Environmental
       Response, Compensation, and
       Liability Act

CERCLA authorizes the federal government to respond to
releases or potential releases of any hazardous substance
into the environment, as well as to releases of pollutants or
                                                  39

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Table 2-6. Summary of Applicable Regulations
       Act or Authority  Applicability
                Application to SNLISEE System
                                    Citation
       CERCLA
Superfund sites
       RCRA
Superfund and
RCRA sites
       CAA
Air emissions
from stationary
and mobile
sources
       TSCA
Poiychlorinated
biphenyl (PCB)
contamination
       AEA and RCRA  Mixed wastes
        OSHA
        Requirements
All remedial
actions
This program authorizes and
regulates the cleanup of
environmental contamination. 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 defines and regulates the
treatment, storage, and disposal of
hazardous wastes. RCRA also
regulates corrective action at
generator and treatment, storage, or
disposal facilities. The ISEE
treatment residual (anolyte)  contains
hexavalent chromium and should be
characterized and disposed of as a
RCRA hazardous waste.

If VOC emissions occur or
hazardous air pollutants are of
concern, these standards may be
applicable to ensure that air pollution
is not associated with the use of this
technology. State air program
requirements should also be
considered.

If PCB-contaminated wastes are
treated, TSCA requirements should
be considered to determine waste
disposal requirements. RCRA also
regulates solid wastes containing
PCBs.

AEA and RCRA requirements apply
to the treatment, storage, or disposal
of mixed wastes containing  both
hazardous and radioactive
components.  OSWER and  DOE
directives provide guidance that
address mixed wastes.

OSHA regulates on-site construction
activities and the health and safety of
workers at hazardous waste sites.
Installation and operation of the
system at Superfund or RCRA sites
must meet OSHA requirements.
40 CFR, Part 300
40 CFR, Parts 260
through 270
40 CFR, Parts 50 and 70
40 CFR, Part 761
                                                    AEA (10 CFR) and RCRA
                                                    (see above)
 29 CFR, Parts 1900
 through 1926
                                                   40

-------
 contaminants that may present an imminent or significant
 danger to public health and welfare or the environment.

 As  part of  the  requirements of  CERCLA,  EPA has
 prepared the National Oil and  Hazardous Substances
 Contingency  Plan  (NCP)  for  hazardous   substance
 response. The NCP is codified in 40 CFR, Pait 300, and
 delineates the methods and criteria used to determine the
 appropriate extent of removal and cleanup of hazardous
 waste contamination.

 The Superfund Amendments and Reauthorization Act
 (SARA) amended CERCLA and directed EPA to do the
 following:

  •  Use  remedial alternatives  that  permanently  and
    significantly reduce the volume, toxicity, or mobility
    of hazardous substances, pollutants, or contaminants

  •  Select remedial actions that protect human health and
    the environment, are cost-effective, and involve
    permanent  solutions  and alternative treatment or
    resource  recovery technologies to  the maximum
    extent possible

  •  Avoid off-site transport and disposal of untreated
    hazardous substances or contaminated materials when
    practicable  treatment  technologies  exist  (Section
In general, two types of responses are possible under
CERCLA: removal and remedial actions. The SNL ISEE
system is likely to be part of a CERCLA remedial action.
Nine general criteria that must be addressed by CERCLA
remedial actions are listed in Table ES-1 of the Executive
Summary.

On-site remedial actions must comply with federal and
more stringent state ARARs. ARARs are determined on a
site-by-site basis and may be waived under six conditions:
(1) the action is an interim measure and the ARA.R will be
met upon remedial action completion, (2) compliance
with the ARAR would pose a greater risk to human health
and the  environment than  noncompliance,  (3) it  is
technically impractical  to  meet  the ARAR, (4) the
standard of performance  of an ARAR can be met by an
equivalent method, (5) a state  ARAR has  not been
consistently applied elsewhere, and (6) ARAR compliance
would not provide  a  balance between the  protection
achieved at a particular site and demands on Superfund for
other sites. These waiver options apply only to Superfund
 actions taken on site, and justification for the waiver must
 be clearly demonstrated.

 CERCLA requires identification and consideration of
 environmental laws that are ARARs applicable to site
 remediation  before  implementation  of a  remedial
 technology at a Superfund site.  Additional regulations
 pertinent to use of the ISEE system are discussed below.
 No direct water discharges are generated by the ISEE
 treatment process; therefore, only regulations addressing
 anolyte characterization and disposal, potential fugitive
 air  emissions from  VOCs  stripped  from  soil,  and
 additional considerations are discussed below.

 2.7.2 Resource Conservation and
        Recovery Act

 RCRA, an amendment to the Solid Waste Disposal Act,
 was passed in 1976 to address the problem of how to safely
 dispose  of the enormous  volume of municipal  and
 industrial solid wastes generated  annually.   RCRA
 specifically addressed the identification and management
 of hazardous wastes.  The  Hazardous and Solid Waste
 Amendments of 1984 greatly expanded the scope  and
 requirements of RCRA.

 The  presence of RCRA-defined  hazardous  waste
 determines whether RCRA regulations apply to the SNL
 ISEE system. If soil or anode effluent are determined to be
 hazardous  waste as  defined  by  RCRA,  all RCRA
 requirements regarding the management and disposal of
 hazardous wastes will need to  be addressed.  RCRA
 regulations define hazardous wastes and regulate their
 transport, treatment, storage, and disposal.   Wastes
 defined as hazardous under RCRA include characteristic
 and listed wastes. Criteria for identifying characteristic
 hazardous wastes are included  in  40 CFR, Part 261,
 Subpart C. Listed wastes from nonspecific and specific
 industrial sources,   off-specification  products,  spill
 cleanups, and other industrial sources are discussed in 40
 CFR, Part 26.1, Subpart D.

 Treatment, storage,  or  disposal of hazardous  waste
typically requires issuance of a RCRA Part B treatment,
storage, or disposal permit. At Superfund sites, the on-site
treatment, storage, or disposal of hazardous waste must
meet the substantive requirements of a treatment, storage,
or disposal permit.  RCRA administrative  requirements
(such as reporting and recordkeeping), however, are not
applicable to on-site actions.
                                                  41

-------
A  Uniform  Hazardous  Waste  Manifest  or its  state
counterpart  must  accompany  off-site  shipment  of
hazardous waste, and transport must comply with U.S.
Department of Transportation hazardous waste packaging,
labeling, and transportation regulations. The receiving
treatment, storage, or disposal facility must be permitted
and in compliance with RCRA standards.

RCRA federal land disposal restrictions (LDR) in 40 C.FR,
Part 268, preclude the land disposal of hazardous waste
that fails to meet stipulated technology  or treatment
standards. In situ treatment of media contaminated with
hazardous waste  does  not trigger LDRs for  soil or
groundwater remaining  in place.  Consequently, soil
treated in situ by the ISEE system does not have to meet
LDRs but may have to  meet other criteria in order to
remain in place. Soil or groundwater removed and treated
must meet LDRs prior to replacement. For the anolyte,
this requirement means  that treatment must reduce the
concentrations of contaminants that make the anolyte
hazardous and all other LDR-triggering contaminants to
levels specified in 40 CFR, Part 268, before the anolyte can
be land disposed. The technology or treatment standards
applicable to residuals produced by the SNL ISEE system
are  determined by the  type  and  characteristics of
 hazardous waste present in the soil being remediated. In
 some cases, variances from LDRs can be obtained from
 EPA.

 Requirements for corrective action at RCRA-regulated
 facilities are provided in 40 CFR, Part 264, Subparts F
 (promulgated) and  S (proposed).  These subparts  also
 generally  apply to remediation  at  Superfund sites.
 Subparts F  and S include requirements for initiating and
 conducting  RCRA  corrective  actions,   remediating
 groundwater, and ensuring that corrective actions comply
 with other  environmental regulations. Subpart S  also
 details  conditions  under  which  particular  RCRA
 requirements can be waived for temporary treatment units
 operating  at corrective  action sites.   Thus, RCRA
 mandates  requirements similar to  CERCLA  and as
 proposed allows treatment units such as the ISEE system
 to operate without the full set of permits.

 2.7.3  Clean Air Act

 The 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 requires  that treatment,
storage, and disposal facilities comply with primary and
secondary ambient air quality standards.  Air emissions
from the ISEE system may result from VOCs from the
vacuum exhaust system and fugitive emissions such as
drilling activities related to system installation (VOC or
dust emissions), periodic sampling efforts, and the staging
and storing of contaminated drill cuttings. VOC emission
control equipment  should  be provided to  reduce
emissions, if the ISEE  system is applied to soils that
contain VOCs. Soil moisture should be managed during
system installation to prevent or minimize impacts from
fugitive emissions. State air quality standards may require
additional measures to prevent fugitive emissions.

2.7.4 Toxic Substances Control Act

The disposal of PCBs is regulated under Section 6(e) of
TSCA.  PCB treatment  and disposal regulations  are
described in 40 CFR, Part 761. Materials containing PCBs
at concentrations of 50 to 500 parts per million (ppm) can
either be disposed  of  in TSCA-permitted landfills or
destroyed by incineration at a TSCA-approved incinerator;
at PCB concentrations exceeding 500 ppm, the material
must be incinerated.

 Sites where spills  of PCBs have occurred after May 4,
 1987, must be addressed under the PCB spill cleanup
 policy in 40 CFR Part 761, Subpart G. This policy applies
 to spills of materials containing 50 ppm or more of PCBs
 and establishes  cleanup protocols for addressing  such
 releases  based on  the volume  and concentration of the
 spilled material. PCBs  were not anticipated to be present
 at the demonstration site; therefore, no analysis for PCBS
 was performed.

 2.7.5 Atomic Energy Act and Resource
        Conservation and Recovery Act

 As defined by the AEA and RCRA, mixed waste contains
 both radioactive and hazardous components. Such waste
 is subject to the requirements of both the AEA and RCRA;
 however, when application of both AEA and RCRA
 regulations results in a situation inconsistent with the AEA
 (for example,  an  increased likelihood  of radioactive
 exposure),  AEA  requirements   supersede  RCRA
 requirements (EPA 1988). Use of the ISEE system at sites
 with radioactive contamination might involve treatment or
 generation of mixed waste.
                                                    42

-------
 OSWER, in conjunction with the Nuclear Regulatory
 Commission, has issued several directives to assist in the
 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 wastes (EPA 1987). If the ISEE system is used
 to treat low-level mixed waste, these directives should be
 considered.   If high-level mixed waste or transuranic
 mixed waste is treated, internal DOE  orders should be
 considered when developing a protective remedy (DOE
 1988b).

 2.7.6  Occupational Safety and Health
       Administration  Requirements

 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 Part 1910.120,  "Hazardous
 Waste Operations and Emergency Response." Part  1926,
 "Safety and Health Regulations for Construction," applies
 to any  on-site construction  activities.  For example,
 electric utility hookups for the ISEE system must comply
 with  Part  1926, Subpart K, "Electrical."   Product
 chemicals such as NaOH used with the ISEE system must
 be managed in accordance with OSHA requirements (for
 example, Part 1926, Subpart D, "Occupational Health and
 Environmental  Controls,"  and Subpart H, "Materials
 Handling, Storage, and Disposal"). More stringent state or
 local requirements must also be met,  if applicable.  In
 addition, health and safety plans for  site  remediations
 should  address  chemicals  of  concern  and  include
 monitoring practices  to ensure that worker health and
 safety are maintained.

 2.8    State and  Community Acceptance

 Because few applications of the SNL ISEE system  have
been attempted beyond the bench- or pilot-scale, limited
 information  is  available to assess state and community
 acceptance of the system. The fact that the ISEE system
allows in situ remediation of contaminated  soils should
 improve the potential for community acceptance because
excavation of contaminated soil often  releases volatile
contaminants.   Although  some  contaminants  may  be
released  during electrode  and  ancillary equipment
installation, the potential for emissions during drilling is
substantially  lower  than  during excavation.    State
• acceptance of the technology may involve consideration
 of performance data from applications such as the SITE
 demonstration and results from on-site, pilot-scale studies
 using the actual wastes to be treated during later, full-scale
 remediation.:
                                                  43

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                                             Section  3
                                      Economic Analysis
3.1    Introduction

The  primary  purpose of this economic  analysis is to
provide a cost estimate (not including profit) for using the
SNLISEE system to commercially remediate unsaturated
soils contaminated with  hexavalent chromium.  This
analysis is based on the assumptions and costs provided by
SNL and on the results and experiences gained from the
SITE demonstration conducted over a 6-month period at
SNL's UCAP. During the SITE demonstration,  13 tests
were performed during six phases. The first 12 tests were
conducted so that SNL could determine preferred ISEE
system operating conditions for Test 13 and to facilitate
the migration of hexavalent chromium toward the central
portion of the test area.  Therefore, this cost estimate is
based on the preferred operating conditions documented
during Test 13. Test 13 targeted a central portion of the
demonstration area, utilizing four anodes and  eight cold
finger cathodes.

Economic  calculations were performed for  the SITE
demonstration Test 13 treatment area, treatment depth,
and operating parameters. SNL anticipates that the cost
for operating the small-scale ISEE system used during
Test 13 will be significantly higher than the  cost for
operating a full-scale, commercialized ISEE system.  SNL
states that a full-scale, commercialized system would be
designed with significant improvements over the system
operated during the demonstration.  However, SNL has
not yet completed the design. Therefore, it is not possible
to prepare a cost estimate for operating the full-scale ISEE
system.   When  the   technology  is  ready   for
commercialization, further economic analysis should be
performed to obtain the costs of operating the system
during a site remediation.

 A number of factors affect the cost of treatment. These
 include, but are not limited to, treatment area, treatment
depth,  initial contaminant concentration, final  target
contaminant concentration, soil characteristics, online
percentage  of system operation, hexavalent chromium
removal  rate,  and  hexavalent  chromium  removal
efficiency. This economic analysis assumes that the SNL
ISEE system will remediate unsaturated soils  with the
same characteristics as soil at the UCAP site.

During Test 13 of the  SITE demonstration, the ISEE
system treated a volume of approximately 16 cubic yards
(yd3) of soil contaminated with hexavalent  chromium.
This volume is based on the assumption that the effective
treatment depth is 6 feet, the treatment area width is 6 feet,
and the treatment area length is  12 feet. During Test 13,
soil was treated for over 700 hours from October 21 to
November  24,  1996.  SITE  demonstration  results are
presented in Section 2 of this report.

Treatment costs were estimated for using the Test 13 ISEE
system configuration to treat 16 yd3 of soil and remove 200
g  of hexavalent chromium (the approximate  mass of
hexavalent  chromium removed during Test 13).

Estimated treatment costs, issues and assumptions, and the
basis for the economic analysis are discussed below.

3.2   Issues and Assumptions

The cost estimates presented in this economic analysis are
representative of charges typically assessed to the client by
the  vendor but do  not include  profit.   In  general,
assumptions are based  on information provided  by the
developer and on observations during this and other SITE
evaluation projects.

Many actual or potential costs are not included as part of
this cost estimate.  They were omitted because  site-
specific engineering designs that are beyond the scope of
                                                   44

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this  SITE  project would be  required.   Also, certain
functions  were assumed  to be the obligation of the
responsible party or site  owner and therefore are not
included. These costs are site-specific. Thus, calculations
are left to the reader so that relevant information may be
obtained  for  specific  cases.   Whenever   possible,
applicable information is provided on these costs so that
the reader can independently complete the  calculations
required to calculate relevant economic data.

Other   important  assumptions  regarding  operating
conditions and task responsibilities that could significantly
alter the cost estimate are discussed below.

 •  The site has been adequately characterized during
   previous investigations.

 •  Treatability studies or pilot-scale studies have already
   been performed.

 •  The site has suitable access roads.

 •  The site has electrical supply lines, telephone lines or
   cellular telephone service, and potable water.

 •  Hexavalent chromium  is  being  removed  from
   unsaturated soil similar to UCAP soil.

 •  Based  on Test 13  results, the ISEE system will on
   average remove hexavalent chromium at a rate of 0.29
   g/hour, with an overall removal efficiency of 0.14 g of
   hexavalent chromium per kW-h.

 •  Based on information from  the developer, the online
   percentage will be  85 percent for the ISEE system.

 •  Based  on the hexavalent  chromium  removal rate
   measured during Test 13 and an online percentage of
   85 percent, the treatment time for the ISEE  system is
   approximately 5 weeks to remove 200 g of hexavalent
   chromium.

 •  Based  on  information from the  developer,  the
   combined total operating and maintenance labor time
   during on-site treatment is 8 hours/week.

 •  Based on information from the developer, 80 hours of
   labor will be required for startup of the ISEE system.
 3.3    Basis for Economic Analysis

 To compare the cost effectiveness technologies evaluated
 under the SITE program, EPA breaks down costs into the
 following 12 categories (Evans 1993):

  •  Site and facility preparation costs

  •  Permitting and regulatory costs

  •  Equipment costs

  •  Startup and fixed costs

  •  Labor costs

  •  Supplies and consumables costs

  •  Utilities costs

  •  Effluent treatment and disposal costs

  •  Residuals and waste shipping, handling, and transport
    costs

  •  Analytical costs

  •  Facility modification, repair, and replacement costs

  •  Site restoration costs

These 12 cost categories reflect typical cleanup activities
encountered at Superfund sites.  Each  of these  cost
categories is.defined and discussed below and form the
basis for the detailed estimated costs presented in Tables
3-1 and 3-2. Table 3-1 provides a detailed breakdown by
cost category. Table 3-2 lists each category's cost as a
percent of the total cost.   Costs assumed to be the
obligation of the responsible party or site owner are
omitted from this cost estimate and are indicated by a line
(—) in Tables 3-1 and 3-2.  Categories with no associated
costs are indicated by a zero (0) in Tables 3-1 and 3-2.
Costs presented in  this report  are order-of-magnitude
estimates as defined by the American Association of Cost
Engineers, with an expected accuracy within +50 percent
and -30 percent; however, because this technology is new,
the actual range may be wider.   The  12 cost categories
examined and assumptions made are also described in
detail below.
                                                   45

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Table 3-1. Estimated Costs for Treatment Using the SNL ISEE System
     Total Treatment Volume
     Mass of Hexavalent Chromium Removed
     Treatment Time

     Cost Categories      	
 16yd3
 200 g
5 weeks

 $/yd3
     Site and Facility Preparation Costs
             Site design and layout
             Survey and site investigations
             Legal searches
             Access rights and roads
             Preparation for support facilities
             Auxiliary buildings
             Transportation of waste feed
             Technology-specific requirements
     Total Site and Facility Preparation Costs

     Permitting and Regulatory Costs
             Permits
             System monitoring requirements
             Development of monitoring and analytical protocols
     Total Permitting and Regulatory Costs

      Equipment Costs
             Annualized purchased equipment cost
             Equipment rental/lease
      Total Equipment Costs

      Startup and Fixed Costs
             System installation
             Startup labor
             Equipment mobilization
             Insurance and taxes
             Initiation of monitoring programs
             Contingency
      Total Startup and Fixed Costs

      Labor Costs
             Operation
      Total Labor Costs

      Supplies and Consumables Costs
             Anode casings
             Cathode casings
             Plumbing
             PPE
             Sodium hydroxide
      Total Supplies and Consumables Costs

      Utilities Costs
              Electricity
              Water
      Total Utilities Costs
     188
     188
      48
      25
      73
     312
     250
      94
     656
     125
     125
       0
       0
       0
       2
       7
       9
       10
       <1
       10
                                                   46

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Table 3-1. Estimated Costs for Treatment Using the SNLISEE System (continued)
    Total Treatment Volume
    Mass of Hexavalent Chromium Removed
    Treatment Time

    Cost Categories
                                                                             16yd3
                                                                             200 g
                                                                            5 weeks

                                                                             $/yd3
    Effluent Treatment and Disposal Costs
            On-site facility costs
            Off-site facility costs
                  -anode effluent                                                             46
                  -cathode effluent                               '                             0
    Total Effluent Treatment and Disposal Costs                                               46

    Residuals and Waste Shipping, Handling and Transport Costs
            Drill cuttings                                                                      §8
            PPE and small equipment                                                          16
    Total Residuals and Waste Shipping, Handling and Transport Costs                         114

    Analytical Costs
            Operations (for developer's purposes)                                                 6
            Environmental monitoring (regulatO'iy)
    Total Analytical Costs                                                                     6

    Facility Modification, Repair, and Replacement Costs
            Design adjustments                                                                 0
            Routine maintenance (materials and labor)a                                            0
            Equipment replacement                                                             0
    Total Facility Modification, Repair, and Replacement Costs"                                  0

    Site Restoration Costs
            Site cleanup and restoration
            - Technology specific                                                             141
            Permanent storage
    Total Site Restoration Costs                                                             141
    TOTAL OPERATING COSTS"
                                                                             1,368
                                                                             (1,400)
    Notes:

    9
    PPE
    yd3
=      Gram
=      Personal protective equipment
=      Cubic yard
=      Cost omitted because assumed to be responsible party or site owner obligation
=      Less than
Maintenance labor is included under operating labor costs.
Total operating costs rounded off nearest $100.
                                                 47

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Table 3-2. Estimated Cost Percentages for Treatment Using the SNLISEE System
Total Treatment Volume
Mass of Hexavalent Chromium Removed
Treatment Time
Costs Units
Site Facility Preparation Costs
Permitting and Regulatory Costs
Equipment Costs
Startup and Fixed Costs
Labor Costs
Supplies and Consumables Costs
Utilities Costs
Effluent Treatment and Disposal Costs
Residuals Shipping, Handling, and Transport Costs
Analytical Costs
Facility Modifications, Repair, and Replacement Costs
Site Restoration Costs
Total Costs ($/yd3)
Notes:
g = Gram
yd3 = Cubic yard
16yd3
200 g
4 weeks
($/yd3)
188
—
73
656
125
9
10
46
114
6
Oa
141
1,368
.


13.7%
—
5.3%
47.9%
9.1%
0.6%
0.7%
3.4%
8.3%
0.4%
Oa%
10.3%



                      Cost omitted because assumed to be responsible party or site owner obligation
              Maintenance labor is included under operating labor costs.
                                                      48

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 3.3.1 Site and Facility Preparation Costs

 For the purposes of these cost calculations, "site" refers to
 the location of the contaminated area. It is assumed that
 preliminary site preparation will be performed  by the
 responsible  party  or  site  owner.  The  amount  of
 preliminary site preparation required depends OKI the site.
 Site preparation responsibilities include assessment of site
 design and layout, surveys and site investigations,  legal
 searches, securing of access rights and construction of
 access roads, preparation of support and decontamination
 facilities, construction of fixed auxiliary buildings, and
 transportation of waste feed. Because these costs are site-
 specific,  they are  not included  as part  of the site
 preparation costs in this estimate.

 The  cost  estimate  assumes  that  the  site  has been
 characterized  during previous investigations; therefore,
 characterization  data are  available to document the
 electrical conductivity of soil pore water, contain.inant ion
 concentrations in the pore water,-hydraulic conductivity,
 soil moisture content, subsurface conditions regarding any
 metallic objects, soil mineralogy,  and  the  presence  of
 VOCs in soil.

 For these cost calculations, only technology-specific site
 preparation costs are included.  These costs are limited to
 costs  for connecting utilities to the ISEE system.  It is
 assumed that the site has electrical supply lines, telephone
 lines (or a cellular telephone service), and potable water.
 The developer estimates the cost for utilities connection to
 be $3,000.

 3.3.2  Permitting and Regulatory Costs

 Permitting and   regulatory costs   are  generally  the
 obligation of the responsible party or site owner.  These
 costs may include actual permit costs, system monitoring
 requirements, development of monitoring and analytical
 protocols, and health and safety monitoring. Permitting
 and regulatory costs can vary greatly because they are site-
 and waste-specific.  No permitting costs are included  in
this analysis. Depending on the treatment site, these costs
can be a significant factor because  permitting can be
expensive and time consuming.

3.3.3 Equipment Costs

Equipment costs include purchased and rented equipment.
Purchased equipment costs are presented as annualized
 costs and are prorated based on the amount of time the
 equipment  is  used for the project.   The annualized
 purchased equipment cost is calculated based on a 15-year
 equipment life and a 6 percent annual interest rate. The
 annualized equipment cost is based on the writeoff of the
 total initial capital equipment cost  and  scrap  value
 (assumed tq  be zero) using  the  following  equation
 (Douglas 1988; Peters 1980):
 Capital recovery = (V - V )
                          S
                                            (3-1)
where:
V
Vs
n
i
               cost of the original equipment
               salvage value of equipment
               equipment life
               annual interest rate
 Purchased equipment for the ISEE technology includes
 four anodes, eight cold finger cathodes, a water control
 system, a vacuum control system, a power supply system,
 and a monitoring system. This cost estimate assumes that
 ISEE system used during Test 13 requires one vacuum
 pump, one air compressor, two chillers, four controllers
 (one for each anode), one rectifier, electrode cabling, one
 skid loader, and one hurricane sampler. The developer
 estimates the total capital cost of the ISEE system used
 during Test 13 to be $78,400.   This cost was used to
 calculate the prorated annualized purchased equipment
 cost based on. treatment time for the ISEE system.  Based
 on  the  hexavalent chromium removal rate measured
 during Test 13 and an online percentage of 85 percent, the
 treatment time for the ISEE system is approximately 5
 weeks to remove 200 g of hexavalent chromium.

 Rented equipment includes a trailer at a rate of $200 per
 month  based on a 30-day month.  This cost estimate
 assumes that a trailer will be rented for 2  months for
 removing 200 g of hexavalent chromium.

If the ISEE system is applied to soils that contain VOCs,
the VOCs would be stripped from the soil matrix and VOC
monitoring  equipment  would   be  required.     This
requirement would result in increased costs for purchased
equipment and increased costs for VOC migration control
and monitoring (depending on the VOC migration control
equipment selected).
                                                   49

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3.3.4 Startup and Fixed Costs

For these cost calculations, startup and fixed costs include
system installation (costs) estimated by the developer to
be $5,000; startup labor costs estimated by the developer
to be 80 hours at a rate of $50 per hour; and equipment
mobilization costs estimated by the developer to  be
$1,500.  System installation  includes costs (including
labor) for installing the anodes, the cold finger cathodes,
plumbing,  and  all  other aboveground  ISEE system
equipment. Startup labor includes shakedown testing of
the ISEE system. Mobilization costs assume that all of the
ISEE equipment (including the  control trailer) can be
mobilized to the site for $1.50 per mile for 1,000 miles.
This cost estimate assumes  that treatability studies or
pilot-scale studies  have  already  been  performed.
Technology-specific site preparation costs are discussed
in Section 3.4.1.

No insurance and taxes, initiation of monitoring programs,
or contingency costs are included because the demonstration
system is not designed to be a commercial system. Often,
insurance and taxes can be estimated to be 10 percent of
the  total  annual purchased  equipment  costs.   Also,
depending on the site and location of the ISEE system,
local authorities may impose specific  guidelines  for
monitoring programs.  The stringency and frequency of
monitoring required  may have significant  impact on
project costs. Contingency costs are often equal to the cost
of insurance and taxes.  Contingency costs allow for
unforeseen or  unpredictable cost conditions, such as
Strikes, storms, floods, and price variations (Peters 1980;
 Garrett 1989).

 3.3.5 Labor Costs

 Hourly  labor  rates  for ISEE system  operation  are
 estimated at $50 per hour and include base salary, benefits,
 overhead, and general and administrative expenses.  For
 this cost estimate, operating labor is assumed to consist of
 one  worker for 8 hours per week  during  treatment.
 Operating labor includes time for general  maintenance of
 the ISEE system. In addition, operating labor includes
 time for activities such as collection of anode effluent
 samples, replacement of full effluent barrels, addition of
 sodium hydroxide to the pH control barrels, soil moisture
 content measurement using neutron hydroprobes, and
 field analysis of hexavalent chromium in anode effluent
 samples.
3.3.6 Supplies and Consumables Costs

Supplies  costs  are limited to  personal   protective
equipment (PPE), anode casings, cathode casings, and
plumbing supplies. The cost of PPE is estimated at $5 per
week. SNL does not expect to replace the anode casings,
the cathode casings, or the plumbing while operating the
ISEE system for removing 200 g of hexavalent chromium
because of short duration of treatment.

Consumables costs are limited to sodium hydroxide. It is
assumed that sodium hydroxide volume requirements are
based on observations made by the developer during Test
13 of the SITE demonstration (65 g of sodium hydroxide
per hour at a cost of $2 per kilogram of sodium hydroxide).

3.3.7 Utilities Costs

Utilities required are limited to electricity and water for the
electrodes,  chillers, and  control  equipment.  Costs for a
telephone line for remote access to the data logger are not
included because they are assumed to be the obligation of
the responsible party or site owner.  The volume of water
required is estimated to be  6 gallons per day based on the
average volume  of effluent collected  during Test  13.
Water rates are assumed to be $0.20 per 1,000 gallons.
Electricity for the electrodes  is based on the 0.14 g/kW-h
hexavalent chromium removal efficiency calculated  for
Test 13. Based on information provided by the developer,
 electricity  for  the chillers  is  estimated to equal  the
 electricity required for the electrodes, and electricity for
the control equipment is estimated to be one-quarter of the
 electricity required for the electrodes. Electricity costs are
 based on an assumed removal efficiency of 85 percent and
 electricity rates of $0.05/kW-h.

 3.3.8 Effluent Treatment and Disposal
        Costs

 Anode effluent requires effluent treatment and disposal.
 For this cost estimate, it is assumed  that the effluent
 disposal cost (including transportation) is $185 per 55-
 gallon drum. Effluent volumes generated are based on the
 average volume of anode  effluent generated during Test
 13 (approximately 6 gallons per day).
                                                     50

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 3.3.9  Residuals and Waste Shipping,
        Handling, and Transport Costs

 It is  assumed that the  only  residuals  or solid wastes
 generated from  use of the ISEE system will be drill
 cuttings and used PPE and small equipment. The disposal
 cost (including transportation) for solid waste is estimated
 at $260 per 55-gallon drum.   If the solid waste is not
 classified as hexavalent chromium-contaminated,  the
 disposal cost may be less.  For this cost estimate, it is
 estimated that six 55-gallon drums of drill cuttings and one
 55-gallon drum of used PPE and small equipment will be
 generated for removing 200  g of hexavalent chromium.

 3.3.10 Analytical Costs

 Only spot checks executed at the developer's discretion (to
 estimate hexavalent chromium concentrations  in  the
 anolyte and to verify that the ISEE system is functioning
 properly) are included in this cost estimate. The client may
 elect or may be required by  local authorities to initiate a
 planned sampling and analytical program at the client's
 expense. The cost for the  developer's spot  checks is
 estimated at $5 per sample for field analysis.  For the
 purposes of this cost estimate, it is assumed that one
 sample per week per anode will be field analyzed. Labor
 costs for collection of samples, field analysis of samples,
 and evaluation of field data are included under labor costs.

 The  analytical   costs associated  with  environmental
 monitoring are  not included  in this estimate because
 monitoring programs are not  typically initiated  by the
 developer.   Local authorities may, however,  impose
 specific sampling and monitoring requirements; therefore
 analytical costs could contribute significantly to the cost of
the project.

 3.3.11  Facility Modification, Repair,  and
        Replacement Costs

System  maintenance costs  are assumed to  consist of
maintenance labor and materials. Maintenance costs are
limited to supplies and labor.  Maintenance supplies are
included under   supplies  and   consumables  costs.
Maintenance labor costs are  included as operating labor
under labor costs. As stated above, the developer plans to
significantly redesign the ISEE technology for full-scale
remediation. Therefore, no facility modification costs are
included for the ISEE demonstration system used for this
 cost estimate. Future cost analysis of the commercialized
 ISEE system should include site modification costs, and
 these costs would be more indicative of site modification
 costs for the ISEE system.

 3.3.72 Site Restoration Costs

 Site restoration requirements vary depending on the future
 use of the site and are assumed to be the obligation of the
 responsible party or site owner.  Therefore, the only site
 restoration costs included are for technology-specific site
 restoration,  including demobilization of  ISEE system
 equipment and grouting the electrode boreholes.   The
 developer estimates thattechnology-specific site restoration
 costs  will be limited $1,500 for demobilizing the ISEE
 system equipment and $750 for grouting the boreholes.

 3.4    Conclusions

Because the treatment volume is only 16 yd3 and the ISEE
system configuration used during Test 13 is currently at
the pilot-scale level, the cost per yd3 of treated soil is very
high; the estimated treatment costs are about $1,400 per
yd3 for 200 g of hexavalent chromium removed. If SNL is
able to further optimize the ISEE system configuration so
that hexavalent chromium  removal rate increases from
that calculated for Test 13, treatment time and costs will be
lower. As mentioned above, costs from economic analysis
of a full-scale ISEE system would be more indicative of
costs of a commercial-scale ISEE system.
                                                  51

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                                              Section 4
                                       Technology Status
The SNLISEE system SITE demonstration has shown that
in situ remediation of chromate-contaminated, unsaturated
sandy soil at the field scale is possible. Vendor claims for
the ISEE system technology are discussed in the appendix.
Chromate ions were transported electrically through soil
to  anodes and  then  extracted to  the soil  surface.
Furthermore, the ISEE system controlled water addition
so that the net addition of water to soil was negligible
during the demonstration.

The SNL ISEE system electrode lysimeters can treat soil
having virtually  any  moisture  content.   Previous
electrokinetic treatment methods are confined to saturated
soil and clay near saturation.  The ISEE system's porous
ceramic casings contain contaminants in electrolyte fluid
that can be pumped out and disposed of. Unlike traditional
electrokinetic extraction systems that use groundwater
wells, the ISEE system's lysimeter system controls the
amount of water pumped out of the electrodes.

Presently, the ISEE system  demonstrated at UCAP is
housed in a portable semitrailer. This trailer houses the
electrode  controls,  power  supply  system,  and data
collection system, the trailer can also serve as a portable
laboratory for on-site analyses.  Up to 10 electrode pairs
can be powered using the configuration used during the
SITE demonstration.

Data obtained from this demonstration allowed SNL to
develop a three-phase, sequential approach to evaluate a
 potential site for electrokinetic remediation. During Phase
 I, SNL will collect existing information and perform a
 preliminary assessment of the applicability of electrokinetic
 remediation to a site. If the site looks promising, Phase 2
 will  be  conducted to further evaluate  site soil and
 contaminants and to provide additional information for
 Phase 3. Phase 3 consists of design of the remediation
 system and calculation of the total costs of remediation.
Site information pertinent to electrokinetic remediation
includes the following:

General information

 •  Contaminated area size and depth

 •  Utilities layout

 •  Depth to groundwater

 •  Soil type and moisture content profile

Chemical information

 •  Contaminant type

 «  Contaminant concentrations and distribution

 •  Pore water electrical conductivity

 •  Soil buffering capacity

 •  Sorption isotherm contours

 •  Concentration of other ions and their distribution

 Other information

  •  Electrical conductivity distribution

  •  Electrical conductivity functionality with respect to
    moisture content

  •  Zeta potential measurements

  •  Surface geophysical surveys

 Phase 2 would involve a bench-scale feasibility study to
 evaluate potential cleanup levels. Soil collected from the
 proposed site would be placed in electrokinetic plexiglass
                                                     52

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cells with an electrode at each end. A constant current
would be applied to each cell, and periodic measurements
would be taken to evaluate contaminant movement as a
function of applied current (in amperes) per hour. Overall
removal efficiency and residual contaminant concentrations
would then be calculated. Additional testing would also be
conducted during Phase 2, such as chemical and electrical
analysis of soil, if this information was not obtained during
Phase 1.

During  Phase 3, full-scale system  design would  be
performed, and parameters such as electrode spacing,
length  of time for  remediation,   expected  power
requirements,  and total cost  of remediation could  be
determined.
                                                   53

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                                           Section 5
                                          References
Douglas, J.M.  1988.  Conceptual Design of Chemical
   Processes. McGraw Hill, Inc. New York, New York.

Evans, G.M. 1993. "Estimating Innovative Technology
   Costs for the SITE Program." Journal of Air Waste
   Management. Volume 40, Number 7.

Garrett, D.E. 1989. Chemical Engineering Economics.
   Van Nostrand Reinhold.  New York, New York.

Hunter, R.J. 1981. Zeta Potential in Colloid Science.
   Academic Press. London.

Krause,T.R.andB.Tarman. 1995. "PreliminaryResults
   from  the Investigation  of  Thermal Effects  in
   Electrokinetic Soil Remediation." American Chemical
   Society  Proceedings.    Presented  at Emerging
   Technologies in Hazardous Waste Management V
   Conference.  September 27 through 29.

Lindgren,  E D., and others.   1991.  "Electrokinetic
   Remediation of Contaminated Soil." Presented at the
   Environmental  Restoration  '91 Conference Pasco,
   Washington. September 8 through 10.

Mattson,E.D., and R.E. Lindgren. 1994. "Electrokinetics:
   An Innovative Technology for In-Situ Remediation of
   Heavy  Metals."  Presented at the Eight  National
   Outdoor Action and Symposium. May 23 through 25.

Mattson.E.D., and R.E. Lindgren. 1993.  "Electrokinetic
   Extraction of Chromate from Unsaturated Soils."
   Presented at Emerging Technologies in Hazardous
   Waste Management V. September 27 through 29.

Peters, M.S.  1980.  Plant Design and Economics for
   Chemical Engineers.  Third Edition. McGraw Hill,
   Inc.  New York, New York.

SandiaNational Laboratories (SNL). 1994. "Superfund
   Innovative   Treatment  Technology  Evaluation
  Demonstration Proposal  for In Situ Electrokinetic
  Extraction [ISEE] System."  EPA Proposal No. 14.
  June 30.

SNL.   1997.   "Electrokinetic Demonstration at the
  Unlined Chromic Acid Pit." SAND97-2592, October
   1997.

Shapiro, A. J. Dissertation Submitted to the Massachusetts
  Institute of Technology. 1990

Tetra  Tech EM  Inc.   1997.   Interview  Regarding
  Additional   Information  for  the  ISEE  System
  Technology Evaluation Report.  Between Cristina
  Radu,  Environmental Engineer,  and Earl Mattson,
  Hydrogeologist, Sat-Unsat, Inc. June 11.

U.S. Department of Energy (DOE).  1988a. DOE SNL.
   1995.     RCRA  Research,  Development   and
  Demonstration Permit No. NM5 890110518-RDD3
   for ISEE System Demonstration.  Permit Attachment
   G.  July.

DOE.  1988b.  Radioactive Waste Management Order.
   DOE Order 5820.2A. September

U.S. Environmental Protection Agency (EPA).  1987.
  Joint EPA-Nuclear Regulatory Agency Guidance 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.   CERCLA  Compliance  -with  Other
   Environmental Laws: Interim Final. OSWER. EPA/
   540/G-89/006. August.

EPA.  1997. "In Situ Electrokinetic Excavation System.
   SNL.    Technology Evaluation  Report.   Draft."
   September.
                                                 54

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                                            Appendix A
                            Vendor's Claimsfor the Technology
 The Superfund Innovative Technology Evaluation (SITE)
 demonstration of the In Situ Electrokinetic Extraction
 (ISEE) system developed by SandiaNational Laboratories
 (SNL) confirms that electrokinetic extraction is a viable in
 situ remediation alternative for the removal of heavy
 metals from unsaturated soils. Electric current is applied
 to soil to be remediated, thereby causing soluble rnetals to
 migrate to an electrode where they are removed using the
 patented SNL technology.  Advantages and innovative
 features  of the ISEE system  and the  status  of the
 electrokinetic technology are discussed below.

 Advantages and Innovative Features

 Advantages  and innovative features of the ISEE system
 are as follows:

 •  Works in soil with low moisture content and effective
    in sandy and clayey soils

 •  Contaminant removed from unsaturated soil

 •  No net water addition to soil

 •  Soil remediated to less than toxicity characteristic
    leaching procedure (TCLP) limits

 •  Compatible with biodegradation remediation systems

 •  Can be used as a contaminant barrier under landfills

 •  Remaining soil   not  sterile  when  remediation
    completed

Electrokinetic Technology Status

Although  electrokinetics was discovered by Reuss in
 1809,  it was not until the mid-1980s that the idea to
remediate soil using electrokinetic technology appeared.
Since  1985, numerous laboratory studies and small-scale
 tests  have  been  conducted  to  further characterize
 electrokinetics.   This  emerging  technology  has the
 potential for removing heavy metals, radionuclides, and
 many  organic  species  dissolved in pore water  from
 contaminated  soil.    Presently,   large   field-scale
 demonstrations of electrokinetic technologies are being
 conducted in the United States.

 Removal of many inorganic contaminants by electrokinetic
 remediation in saturated or near saturated soils has been
 documented in literature. Metal cations such as copper,
 zinc, chromium, iron, cobalt, nickel, arsenic, cadmium,
 lead, mercury, and uranium ions, as well as anions such as
 chloride,  cyanide,  nitrate,  and  sulfate, have   been
 successfully removed  from  soil using electrokinetics.
 Although the focus  of electrokinetics  has  been on
 inorganic contamination, organic contaminants such as
 polynuclear  aromatic  hydrocarbons have been  also
 removed (EPRI1994). No theoretical or technical reasons
 are documented to indicate that organic  and inorganic
 contaminants cannot  be removed  using  electrokinetic
 technology on unsaturated soils.

 Recently,  bench-scale  studies  of the use of citrate to
 remove uranium from unsaturated soils were  conducted
 (SNL 1997). In unsaturated soil, uranium normally exists
 primarily as  a; cation in the +6 state as UO2+2 because of
 prevailing oxidation conditions.  In this oxidation state, the
 cation will readily sorb to soil.  During the bench-scale
 studies, citrate  was injected at the  cathode electrode
 casing. The citrate electromigrated across the test cell and
 chemically interacted with the uranium cations to form the
 anionic complex (UO2Citrate)-2. This complex continued
 electromigration to the anode. The uranium complex was
then extracted; from soil through the electrode  casings of
the ISEE system.

It is important to note that the system evaluated during this
 SITE demonstration is an SNL research prototype system
                                                   55

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and not a system that would be used for actual remediation.
The SNLISEE system used for electrokinetic remediation
during the demonstration monitors many parameters
necessary to  evaluate electrokinetics.  To conduct an
actual remediation project, SNL's current research efforts
have developed a low-maintenance extraction system that
can operate unsupervised for long periods of time. This
new system is to be implemented simply through initial
setup, periodic inspection of system operation, and final
dismantlement and removal of system equipment. Cost of
remediation using the new system will be dramatically
reduced because of the passive nature of its operation.

This SITE demonstration shows that electrokinetics is
applicable to unsaturated sandy soil. Contaminants can be
transported through soil pore water and collected and
removed at the electrodes.  By utilizing surfactants or
complexents, electrokinetic remediation can be applied to
many contaminants besides heavy metals.

References

 Electric  Power  Research  Institute (EPRI).    1994.
    Proceedings:   EPRI  Workshop   on  In   Situ
    Electrochemical Soil and Water Remediation.  Palo
    Alto, California. February 28 through March 1.

 Sandia  National  Laboratories  (SNL).     1997.
    "Electrokinetic  Removal  of  Uranium  from
    Contaminated,  Unsaturated Soils."   Albuquerque,
    New Mexico. SAND97-01220. January.
                                                    56

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