«EPA
                                United States
                                Environmental Protection
                                Agency
                           Office of Emergency and
                           Remedial Response
                           Washington, PC 20460
Off ice of
Research and Development
Cincinnati, OH 4§2$8
                                Superfund
                                                     October 1994
Engineering  Bulletin
In  Situ  Vitrification
                                    •  -\ •.
Treatment
 Purpose
    Section 121(b) of the Comprehensive Environmental Re-
 sponse, Compensation, and Liability Act (CERCLA) mandates
 the Environmental Protection Agency (EPA) to select remedies
 that "utilize permanent solutions and alternative treatment
 technologies or resource recovery technologies to the maxi-
 mum extent practicable" and to prefer remedial actions ;n
 which treatment "permanently and  significantly reduces the
 volume, toxicity, or mobility of hazardous substances pollut-
 ants and contaminants as a principal element " The Engineer-
 ing Bulletins are a series of documents that summarize tl le latest
 information available on selected  treatment and site remedia-
 tion technologies and related issues. They provide summaries
 of and references for the latest information  to help remedial
 project managers, on-scene coordinators,  contractors, and
 other site cleanup managers understand the type of data and
 site characteristics needed to evaluate a technology fot poten-
 tial applicabittty to their Superfund or other  hazardous waste
 site. Those documents that describe individual treatment
 technologies focus on remedial investigation scoping needs.
 Addenda  will be  issued periodically to  update the original
 bulletins.
Abstract

    In situ vitrification (ISV) uses electrical power to heat and
melt soil,  sludge, mine tailings, buried wastes, and sediments
contaminated with organic, inorganic, and metal-bearing haz-
ardous  wastes.  The molten material cools to form a hard,
monolithic, chemically inert, stable glass and crystalline prod-
uct that incorporates and immobilizes the thermally  stable
inorganic compounds and heavy metals  in the hazardous
waste. The slag product material is glass-like with very low
leaching characteristics.

    Organic 'wastes are initially vaporized or pyrolyzecf by the
process. These contaminants migrate to the surface where the
majority are then burned within a hood covering the treatment
area; the remainder are treated in an off gas treatment system.

    ISV uses a square array of four electrodes that are inserted
into the surface of the ground. Electrical power is applied to the
electrodes which, through a starter path of graphite and glass

* [reference number, page number]
                           frit, establish an electric current in the soil. The electric current
                           generates heat and melts the starter path and the soil; typical
                           soil melt temperature is 2,900°F to 3,600°F. An electrode feed
                           system (EPS) drives the electrodes in the soil as the molten mass
                           continues to grow downward and outward until the melt zone
                           reaches the desired depth and width. The process is repeated
                           in square arrays until the desired  volume  of soil  has  been
                           vitrified. The process can typically treat up  to 1,000 tons of
                           material in one melt setting.

                              ISV technology has been under development and testing
                           since 1980 [1, p. 1 ]*.  ISV was developed originally for possible
                           application to soils contaminated with radioactive materials. In
                           this application, trans-uranium radionuclides are incorporated
                           in the vitrified mass. At this time there is only one vendor of
                           commercially available in situ vitrification systems.  The
                           technology description, status, and performance data are
                           quoted from the published work of this vendor.

                              ISV is the proposed remediation technology at eight sites,
                           six of which are EPA Superfund sites [2] [3]. Full-scale units have
                           been constructed. Even so, the technology should be consid-
                           ered emerging in its full-scale application to Superfund  sites.
                           EPS mechanisms have recently been developed for pilot- and
                          full-scale systems. This bulletin provides information on the
                           technology  applicability, limitations, the types of residuals
                           produced, the latest performance data, site requirements, the
                          status of the technology, and sources for further information.

                              Site-specific  treatability  studies are the best means of
                          establishing the applicability and projecting  the likely perfor-
                          mance of an ISV system. Determination of whether ISV is the
                          best treatment alternative will be based on multiple site-specific
                          factors, cost, and effectiveness.  The EPA Contact indicated at
                          the end of this bulletin can assist  in the location of other
                          contacts and sources of information necessary for such treat-
                          ability studies.
                          Technology Applicability

                              ISV has been reported to be effective in treating a large
                          variety of organic and inorganic wastes based on the results of
                          engineering- and pilot-scale  tests.  The technology also has
                                                                                        Printed on Recycled Paper

-------
proven effectiveness in treating radioactive wastes based on the
results of full-scale tests.  Radioactive wastes and sludges,
contaminated soils and sediments, incinerator ashes, industrial
wastes and sludges,  medical wastes, mine tailings,  and
underground storage tank waste can all potentially be vitrified
[4, p. 4-1].

    Organic contaminants at concentrations of 5 to 10 perce? it
by weight and inorganic contaminants at concentrations of 5
to 15  percent by  weight are generally acceptable for 15V
treatment [5, p. 1 3]. The effectiveness of the ISV technology on
treating various contaminants in soil, sludge, and sediments is
given in Table 1.  Examples of constituents within contaminant
groups are  provided in  the "Technology Screening Guide for
Treatment of CERCLA Soils and Sludges" [6]. Table 1 is based
on  current available information  or  professional judgment
where no information was available. The proven effectiveness
of the technology for a particular site or waste does not ensure
that it will be effective at all sites or that the treatment levels
achieved will be acceptable at other sites.  For the ratings used
for this table, demonstrated effectiveness means that at some
scale, treatability tests have shown that the technology was
effective for that particular contaminant and matrix.   The
ratings of potential effectiveness or no expected effectiveness
are both based upon expert opinion. Where potential effective-
ness is indicated, the technology is believed capable of success-
fully treating the contaminant group in a particular matrix. The
technology is expected to work for all  contaminant groups
listed.

    ISV processing requires that sufficient glass-forming  ma-
terials (e.g., silicon and aluminum oxides) be present within the
waste materials to form and support a high-temperature melt.
To form a melt, sufficient (typically 2 to 5 percent) monovalent
alkali cations (e.g., sodium and potassium) must be present to
provide the degree of electrical conductivity needed for the
process to operate efficiently.  If the natural material does not
meet this requirement, fluxing materials such as sodium car-
bonate  can  be  added to  the base material. Typically, these
conditions  are  met by most soils, sediments, tailings, and
process sludges.

    Differences in soil characteristics such as permeability and
density generally do not affect overall chemical composition of
the soil or the ability to use ISV. In many site locations, the soil
profile may be stratified and present nonuniform characteristics
that can affect  the melt rate and dimensions of the vitrified
       Before applying the ISV technology, soil stratification
mass.
must be defined so that it may be factored into the remedial
design.
                        Table 1
      Effectiveness of ISV on General Contaminant
        Groups for Soil, Sludges, and Sediments

Contaminant Groups



"c
a
2»
o





o
r

•active
oc
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
Polychlorinated biphenyls (PCBs)
Pesticides (halogenated)
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers

Effectiveness
Soil Sludge Sediments









V
T
T
V

T
T
V
T
T
T
T
V
•
•
T
V
T
T
T
T

V
V
T
T
V
T
V
T
•
•
T
T
T
T
T
T

m Demonstrated Effectiveness: Successful treatability test at
some scale has been completed
T Potential Effectiveness: Expert opinion that technology will
work
D No Expected Effectiveness: Expert opinion that technology
will not work
                                                        [
Limitations

    The ISV process  can treat soils saturated with water;
however,  additional power is used to  dry the soil  prior to
melting and may increase the cost of remediation by  10
percent. ISV is more economical to implement when the soil to
be vitrified has a low moisture content.  Progression of a melt
into saturated  soil enclosed  in a container can result in a
gaseous steam release that can cause the molten  glass to
spatter.

    When treating a contaminated zone in an aquifer, it may
be necessary to  lower the water table below the  zone of
contamination in order to vitrify to the desired depth. Alterna-
tively, a hydraulic barrier (e.g., slurry wall) could be placed
upstream  of the contamination to divert  the aquifer flow
around the treatment zone. Treatment in a water-saturated
zone  may result in movement of some of the contaminants
from  the treatment zone to surrounding areas, thereby reduc-
ing the amount of contaminants being destroyed, immobi-
lized, or removed.

    The  maximum ISV  depth obtainable  is influenced  by
several factors,  including spacing between electrodes, amount
of power available, variations in soil composition and gradation
between  different strata, depth to groundwater, soil perme-
ability within an aquifer, surface heat loss during ISV, and waste
and soil density. To date, treatment depths of only 19 feet have
been demonstrated [4, p. 7-6].

    The presence of large inclusions in  the area to be treated
can limit  the  use of  the ISV process.  Inclusions are highly
concentrated  contaminant layers, void volumes, containers,
rnetal scrap, general refuse, demolition debris, rock, or other
heterogeneous materials within the treatment volume. Figure
                                                        Engineering Bulletin:  In Situ Vitrification Treatment

-------
 1 gives limits for inclusions within the treatment volume [7, p.
 17]. If massive void spaces exist, a large subsidence could result
 in a very short time period. These problems, as well as those
 caused by other large inclusions, may be detected by ground
 penetrometry or other geologic investigations.  Some inclu-
 sions such as void volumes, containers, and solid combustible
 refuse can potentially generate gases. However, the  oversized
 hooding is intended to control and mitigate any release. If large
 volumes of offgases are generated during a short time period,
 the off gas treatment system  may overload, Vitrification of
 flammable or explosive objects can result in  spattering of the
 molten glass. Underground storage tanks can be treated only
 if they are filled with soil prior to the vitrification  process.

     Sampling and analysis of the glass matrix produced by ISV
 is difficult and must be carefully planned prior to conducting a
 treatability study or site remediation. Current EPA  digestion
 methods for metal analyses are not designed to dissolve the
 glass matrix. The metal concentration measured by •.» standard
 nitric/hydrochloric acid digestion (SW 846, Method 3050) will
 likely be highly dependent on the particle size of the material
 prior to digestion. The digestion specified will  not dissolve glass
 but will leach some metals from the exposed surfaces. Closure
 of mass balance for the system, therefore, can often oe incom-
 plete.  However, a recently developed digestion met iod using
 hydrofluoric acid with microwave digestion has beer known to
 improve metal analysis for this type of matrix.
 Technology Description

     Several methods and configurations exist for the applica-
 tion of ISV.  At a site that has only a relatively shallow layer of
 contamination, the contaminated layer may be excavated and
 transported to a pit where the vitrification will take place. At
                         other sites where the contamination is much deeper, thermal
                         barriers could be placed along  the  site to be vitrified  and
                         prevent the movement of heat and glass into adjacent areas.
                         This will force the heat energy downward and melt depths will
                         be increased.

                             This bulletin describes the more conventional approach to
                         using ISV; a checkerboard pattern of melts is used to encapsu-
                         late the waste and control the potential for lateral migration.
                         The holes in the checkerboard are then vitrified to complete the
                         remediation of the site.

                             Figure 2 shows a typical ISV equipment layout. ISV uses a
                         square array of electrodes up to 18 feet apart, which is inserted
                         to a depth of 1 to 5 feet and potentially can treat down  to a
                         depth of 20 feet to remediate a contaminated area. A full-scale
                         system can remediate at a rate of  3 to 5 tons per hour [4, p. 3-
                         6] until a maximum mass of 800 to 1,000 tons has been treated.
                         Since soil is not electrically conductive once the moisture has
                         been driven off, a conductive mixture of flaked graphite  and
                         glass frit is placed between  the electrodes to act as a starter
                         path, as shown in Figure 3. Power is supplied to the electrodes,
                         which establishes an electrical current in the starter path.  The
                         resultant power heats the starter path and surrounding soil up
                         to 3,600°F, which is well above the melting temperature of
                         typical soils (2,000°F to 2,600°F). The graphite starter path
                         eventually is consumed by oxidation and the current is trans-
                         ferred to the soil which is electrically conductive in the molten
                         state. A typical downward growth rate is 1 to 2 inches per hour.
                         The thermal gradient surrounding the melt is typically 300°F to
                         480°F per inch.  As  the vitrified zone grows, it incorporates
                         metals and either vaporizes or pyrolizes organic contaminants.
                         The pyrolyzed products migrate to the surface of the vitrified
                         zone, where they may oxidize in  the presence of oxygen. A
                         hood placed over the processing area is used to collect combus-
                         Figure 1
 General Limits for Inclusion Within Volume to Be Treated
                                                Figure 2
                                         ISV Equipment System
                       Electrodes
    Void
  Volumes
  (individual
  <150cu-ft)
    Rubble
  (10-20wt%)
                 Metal (5-15 wt%)
      Combustible
      Soli-is
      (5-10wt%)
                                              Combustible
                                            - Packages
                                              {individual
                                              <30 eu-ft)
  \
Continuous Metal
(<90% distance
between
electrodes)
                                                                               Off-Gas Hood
                                                                                                       Controlled Air Input
                                                                  Utility or Dtoaal-
                                                                    Generatad
                                                                     Powar
                                                 Clean Emissions
Engineering Bulletin:  In Situ Vitrification Treatment

-------
                                                       Figure 3
                                               Stages of ISV Processing
              Graphite and Glass
              Frit Starter Path
Electrodes to
Desired Depth
                                                        Subsidence
Backfill Over
Completed
Monolith
                            Contaminated
                            Soil Region
                            Natural Soil
                                                 Vitrified Monolith
tion gases, which are treated in an offgas treatment system.

     As  the melt grows downward and outward,  power is
maintained at sufficient levels to overcome the heat losses to
the  hood and surrounding soil.  Generally, the melt grows
outward to form a melt width approximately 50 percent wider
than the electrode spacing. This growth varies as a function c I
electrode spacing and melt depth. The molten zone is roughly
a square with slightly rounded corners, a shape that reflects the
higher power density around the electrodes. As the melt grow s
in size, the electrical resistance of the melt decreases; thus, the
ratio between the voltage and the  current must be adjusted
periodically to maintain operation at an acceptable power
level.

     The EF S, now an integral part of all operations, enhances
the ability of ISV to treat soils containing high concentrations of
metal. In EFS operations, the electrodes are independently fed
to the molten soil as the melt  proceeds downward instead of
being placed in the soil prior  to the startup of the test.  The
system improves processing control at sites with high concen-
trations  of metal. For example, upon encountering a full or
partial electrical short, the affected electrodes are simply raised
and held above the molten metal pool at the bottom of the
melt. During this time, the melt continues to grow downward.
The electrodes can then be reinserted into the melt to the r
original depth and resume electrode feeding operations. These
advances have been incorporated into the pilot- and the full
scale ISV systems [8].

     The treatment area is covered by a newly designed octag
onal-shaped offgas collection hood with a maximum distance
of 60 feet between the sides. The hood has three manual
viewing  ports and provision for video monitoring or recording.
The hood is connected to an offgas treatment trailer and  i
backup  offgas treatment system.   During the process,  the
offgases are drawn by a 1,850 standard cubic feet per minute
(scfm) blower into the trailer,  Flow  of air through the hood is
controlled to maintain a vacuum of 0.5 to 2,0 inches H2O on the
system.  The offgas temperatures are typically 210°F to 750°:
when they enter the treatment system.  The gases are then
                             treated by quenching, scrubbing, mist-elimination, heating,
                             particulate filtration, and activated carbon adsorption.  The
                             backup offgas treatment system is used in the event of a power
                             outage and is powered  by a diesel generator. The backup
                             system is designed to treat gases that may evolve from the melt
                             until power is restored to the process and electrodes [9].
                             Process Residuals

                                 The main process residual produced during operation of
                             the ISV  technology is the vitrified soil itself.  The vitrified
                             monolith is Seft in place after treatment due to its nonhazardous
                             nature. The volume of the ISV product formed generally is 20
                             to 45 percent less than the initial volume treated.  Because of
                             the volume reduction during processing, it is covered with
                             clean backfill.  It is possible, however, to excavate and remove
                             the vitrified soil in smaller pieces  if  onsite  disposal  is not
                             acceptable at a given  site.

                                 Typically, the residual product from soil applications has
                             a compressive strength  approximately 5 to 20 times greater
                             and a tensile strength approximately 7 to 11 times greater than
                             unreinforced concrete [4, p. 5-3]. It is usually not affected by
                             either wet/dry or freeze/thaw cycling [10, p. 3].  Existing data
                             indicate that the vitrified mass is devoid of residual organic* and
                             passes EPA's Toxicity Characteristic Leaching Procedure (TCLP)
                             test criteria for priority pollutant metals.  The ISV residual also
                             has been found to have acceptable biotoxicity relative to near-
                             surface life forms [11,  p. 79]. The clean backfill can be used to
                             revegetate the site or  other end uses.

                                 After processing for a period of time, the scrubber water,
                             filters, and activated carbon may contain sufficient contami-
                             nants to warrant treatment or disposal.  Typical treatment
                             includes passing the contaminated scrubber water through a
                             filter, settling  chamber, and activated  carbon, then either
                             reusing the water or discharging it into a sanitary sewer.  The
                             activated carbon, filter, and the solids from the settling cham-
                             ber can then be placed in an ISV setting for vitrification. In this
                             way, the destruction/chemical incorporation of contaminants
                                                       Engineering Bulletin:  In Situ Vitrification Treatment

-------
 collected in the offgas treatment system is maximized. Only
 residuals resulting from the last setting at a site must be treated
 arid disposed of by means other than ISV.
 Site Requirements

     The components of the ISV system are contained in three
 transportable trailers: an offgas and process control trailer; a
 support trai ler; and an electrical trailer. The trailers are mounted
 on wheels sufficient for transportation to and over a compacted
 ground surface [12, p. 307].

     The site must be prepared for the mobilization, operation,
 maintenance, and demobilization of the equipment  An area
 must be cleared for heavy equipment access roads, automobile
 and truck parking lots, ISV equipment, setup areas, electrical
 generator, equipment sheds, and workers' quarters

     The field-scale ISV equipment system requires three-phase
 electric power at either 12,500 or 13,800 volts, which is usually
 taken from a utility distribution system [1 3, p. 2]. At startup the
 technology requires high voltage (up to 4,000 volts) to over-
 come the resistance of the soil, and a current of approximately
 400 amps. The soil resistance decreases as the melt pt ogresses,
 so that  by the end of the process, the voltage decreases to
 approximately 400 volts and the current,  increases up  to
 approximately 4,000 amps [4, p. 3-6], Alternatively, the power
 may be  generated onsite by means of a diesel generator.
 Typical applications require 800 kilowatt hour/ton (kWh/ton)
 to l,OOOkWh/ton.

     Spent activated carbon, scrubber water, or other process
 waste materials may be hazardous, and the handling of these
 materials requires that a site safety plan be developed  to
 provide for personnel protection and special handling mea-
 sures. Storage should be provided to hold these wastes until
 they have been tested to determine  their acceptability for
 disposal, release, or recycling to subsequent ISV melts Storage
 capacity will depend  on the waste volume generated,

     Site activities such as clearing vegetation, removing over-
 burden,  and acquiring backfill material are often necessary.
 These activities are generally advantageous from a financial
 point of view. For example,  the  cost  of  removal of the
 top portion of clean  soil would generally be much less than
 the cost for labor and energy to vitrify the same volume of soil
 [4, p. 9-6].
Performance Data

    Performance data presented in this bulletin should not be
considered directly applicable  to other Superfund  sites.  A
number of variables such as the specific mix and distribution of
contaminants affect system performance. A thorough charac-
terization  oif the  site and a well-designed and  conducted
treatability study are highly recommended.

    The performance data currently available are  rom the
process developer.  ISV has been developed through four scales
of equipment:  1) bench (5 to 20 pounds); 2) engineering (50
to 2,000 pounds); 3) pilot (10 to 50 tons); and 4) full (500 to
1,000 tons).  The values in parentheses are typical masses of
vitrified products resulting from a single setting at the various
scales. Several tests have been performed at each scale and on
a variety of contaminated media.

    An  engineering-scale test was  performed on loamy-clay
soil containing 500 parts per million (ppm) of PCBs. Figure 4
gives the final concentrations of PCBs (in ppm) in and around
the vitrified block upon completion of the test [1 3, p. 4-3]. This
figure indicates that migration of PCBs outside the vitrified
block is  not a significant concern. Data from offgas emissions
and soil container smears accounted for 0.05 percent by weight
of the initial PCB quantity, which corresponds to a greater than
99.9 percent destruction  efficiency (DE) for the ISV process.
This DE does not include the removal efficiency of the offgas
treatment system.  Activated carbon has a 99.9  percent effi-
ciency and can remove any of these offgas emissions effectively.
Overall, the destruction removal efficiency (ORE) range for the
combined ISV and offgas system is between 6  and 9  nines
which is greater than the 6 nines  DRE required by 40 CFR
761.70 for PCB incinerators. Analysis of the offgas also indi-
cated the presence  of small quantities of polychlorinated
                        Figure 4
      Vitrified Block and Surrounding Soil Sample
           Positions and PCB Concentrations
   Depth
   (inches)
   Or-
  10
  15
  20
                                                                25
  30
  35 -
  40 -
    1.23
         <0.004
                         Subsidence
                         Cavtty  <
      \"'03B-/
       \     f\ HQ /
                        0.005
                                           Initial PCB
                                           Soil Position
       0.08  0.008 <0.004
0 05                   0.002  <0.004
                      010  0.07
              <0.004
     Blank Soil
     <0.004 to 0.09
                              0.07
Engineering Bulletin:  In Situ Vitrification Treatment

-------
dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzof urans
(PCDFs). However,, the levels reported (0.1 \ig/L and 0.4 |j,g/
L, respectively) can be removed by the offgas treatment system.
An  engineering-scale  test on PCB-contaminated sediments
from New Bedford Harbor [4, p, 4-2] gave a similar DE (99.9999
percent) for the ISV process before additional treatment by the
offgas  treatment system.  During feasibility testing of PCB-
contaminated  soil from a Spokane, Washington site, a  DE
greater than 99.993 percent arid a ORE greater than 99.99999
percent were obtained [14]. During engineering-scale testing
of vitrification of simulated wastes from the Hanford Engineer-
ing Development Laboratory, a DRE of greater than 99.99
percent was obtained for a variety of  organic contaminants
[15].

    An engineering-scale test was performed on Idaho Na-
tional Engineering Laboratory spiked soil at the Pacific North-
west Laboratory. The soil was spiked with eight heavy metals
(Ag, As, Ba, Cd, Cr, Hg, Pb, and Se) to 0.02 percent by weight
except for lead which was spiked at 0.2 percent by weight [16 j.
The test results for metals concentrations in the leach extract
and maximum concentration limits established by EPA a e
given in Table  2.

    Feasibility  testing  was conducted using the bench-scale
I SV equipment to treat a sample of soil from the old Jacksonville,
Arkansas water treatment plant [17]. This soil was contaminai -
ed with 2,3,7,8-tetrachloirodibenzo-p-dioxin and placed in a 5-
gallon  can  with a Pyrex-plate lid.  Analytical results did not
detect  any  dioxin or furan in the vitrified material or in the
offgas. Based on analytical detection limits, the DE was greater
than 99.995 percent prior to entry into the offgas treatment
system.

    Ten thousand kilograms of an industrial sludge heavily
                        Table 2
          TCLP Extract Metal Concentrations
         Idaho National Engineering Lab Soils
Metal
Arsenic
Barium
Cadmium
Chromium
Lead
Mercury
Selenium
Silver
Maximum
Allowable
Leachate
Concentration
(mg/L)
5.0
100.0
1.0
5.0
5.0
0.2
1.0
5.0
Contaminated
Soil
Concentration
(mg/kg)
200
200
200
200
2000
200
200
200
Vitrified Product
Leachate
Concentration
(mg/L)
<0.168
0.229
0.0098
0.01 78
0.636
<0.0001
0.098
<0.023
1
       laden with zirconia and lime was vitrified successfully by the
       pilot-scale I SV process. The sludge contained 55 to 70 percent
       moisture by weight. The volume was observed to be reduced
       significantly (more than one-third of original volume) after the
       testing [18, p. 29]. Analysis of the offgas and the scrubber water
       showed that the melt retained between 98 and 99 percent of
       the fluorides, chlorides, and sulfates. Analysis indicated that the
       destruction of organic carbon was good  and that ISV was
       effective in promoting nitrogen oxide (NOX) destruction. This
       result minimizes the concern for environmental impact.

           Soil from a fire training pit contaminated with fuel oils and
       heavy metals was bench-scale tested at the Arnold Engineering
       Development Center in Tennessee [19]. Results of initial testing
       and analyses of the soil indicated that an electrically-conduct-
       ing fluxing agent (such as  sodium carbonate) with a lower
       melting point was required as an addition to the soil for ISV
       processing to work effectively. The onsite pilot-scale process
       achieved a high destruction  of organics  (greater than 98
       percent) and  high  retention of inorganics in the melt. Leach
       testing using Extraction Procedure Toxicity (EP-Tox) and TCLP
       tests showed that all metals of concern were below maximum
       permissible limits.  The  tests indicate that the fluxing agent
       should be distributed throughout the entire vitrification depth
       for optimum operation.
       Technology Status

           The only vendor supplying commercial systems for in situ
       vitrification of hazardous wastes is Geosafe Corporation. Geosafe
       is under  a sublicense from the process developer, Battelle
       Memorial Institute. Four scales of units are in operation ranging
       from bench-scale to full-scale.

           To date, only bench-, engineering-, and pilot-scale test
       results are available on in situ vitrification of hazardous wastes.
       Full-scale tests have been completed only on radioactive wastes.
       Table 3 indicates several sites where I SV has been selected as the
       remedial  action [2].

           In April  1991, a fire involving the full-scale collection ISV
       hooding  occurred at the Geosafe Hanford, Washington test
       site.  The vendor was testing a new, lighter hooding material.
       The hooding caught fire during the test when a spattering of
       the melt  occurred.  For  a period of time after the incident,
       Geosafe suspended full-scale field operations. During this time,
       Geosafe completed analytical, modeling, and  engineering-
       scale testing to allow confident design;  defined  necessary
       process revisions;  finalized design and fabrication  of a  new
       metal offgas collection hood; and performed additional opera-
       tional acceptance testing to demonstrate the capabilities of the
       equipment and operational procedures [20]. The new offgas
       collection hood design is composed entirely of metal rather
       than high-temperature fabric, which was previously used.  The
       new design is heavier than the fabric hood, but is capable of
       being transported by the same equipment.

           Cost estimates for this technology range from $300 to
       $650 per ton of contaminated soil treated. The most significant
       factor influencing cost is the depth of the soil to be treated. High
  6
Engineering Bulletin:  In Situ Vitrification Treatment

-------
                                                      Table 3
                                 Selected Sites Specifying ISV as the Remedial Action
   Site
                                 Primary Contaminants
                                 Status
   Parsons Chemical


   Ionia City Landfill



   Rocky Mountain Arsenal



   Wasatch Chemical
Soil: 2,000 cubic yards (yd3)
Soil with debris: 5,000 yd3
(15 feet deep)


Soil: 4,600 yd3 (10 feet deep)
Sludge: 5,800 yd3 (10 feet
deep)

Soil: 3,600 yd3 (5 feet
deep) sludge, solids
   Transformer Service Facility/  Soil:  3,500 tons
   TSCA Demonstration
   Arnold AFB, Site 10

   Crab Orchard
   Wildlife Refuge
Soil with debris: 10,000 tons

Soil: 40,000 tons
   Anderson Development      Soil: 4,000 ton-
Biocides (pesticides), dioxins,
metals (mercury)

Volatile organic compounds
(methylene chloride, TCA,
styrene, toluene), metals (lead)
Biocides (pesticides), metals
(arsenic, mercury)


Semivolatile organic compounds
(hexachlorobenzene, penta-
chlorophenol), biocides (pesti-
cides), dioxins
PCBs
Mixed organics, heavy metals

PCBs and lead
                                4,4'-rnethylene bis
                                (2-chloroaniline) (MBOCA)
 Site preparation


Treatability testing



Remedial design



Remedial design



Site preparation


Site preparation

Predesign


 Predesign
moisture content requires that additional energy be i ised to dry
out the soil! before the melting process can begin, thus increas-
ing the cost. Other factors that influence the cost of remedia-
tion by ISV are:  the amount of site preparation required;
the specific properties of  the contaminated soil (e.g., dry
density); the required depth of processing; and the unit price
of electricity.
EPA Contact

    Technology-specific questions  regarding  ISV  may  be
directed to:

    Ms. Teri Richardson
    U.S. Environmental Protection Agency
    Risk Reduction Engineering Laboratory
    26 West Martin Luther King Drive
    Cincinnati, Ohio 45268
    (513)569-7949
                                Acknowledgments

                                    This bulletin was prepared for the U.S. Environmental
                                Protection Agency, Office of Research and Development (ORD),
                                Risk Reduction Engineering Laboratory (RREL), Cincinnati, Ohio,
                                by Science Applications  International Corporation (SAIC) un-
                                der Contract No. 68-CO-0048. Mr. Eugene Harris served as the
                                EPA Technical Project Monitor.  Mr. Jim Rawe was SAIC's Work
                                Assignment Manager.   Dr.  Trevor  Jackson (SAIC)  was the
                                primary author.  The author is especially grateful to Ms. Teri
                                Richardson of EPA-RREL, who contributed significantly by serv-
                                ing as a technical consultant during the development of this
                                document.

                                    The following other Agency  and contractor personnel
                                have contributed their time and comments by participating in
                                the expert review meetings or peer reviews of the document:
                                    Mr. Edward Bates
                                    Mr. Briant Charboneau
                                    Mr. Kenton Oma
                                    Mr. Eric Saylor
                               EPA-RREL
                               Wastren, Inc.
                               Eckenfelder, Inc.
                               SAIC
Engineering Bulletin:  In Situ Vitrification Treatment
                                                                •&U.S. GOVERNMENT PRINTING OFFICE: 1994 550-067/H0280

-------
                                                REFERENCES
 1   Geosafe Corporation. In Situ Vitrification for Permanent
     Treatment of Hazardous Wastes.  Presented at Advances
     in Separations; A Focus on Electrotechnologies for Prod-
     ucts and Waste, Battelle, Columbus, 1989.
 2.   Innovative Treatment Technologies, Semi-Annual Stati s
     Report (Fourth Edition). EPA/542/R-92/011, U.S. Envi-
     ronmental Protection Agency, October 1992.
 3.   Conversations with Hansen, J. of Geosafe  April 19
     1993.

 4.   Vitrification Technologies for Treatment of Hazardous
     and Radioactive Waste. EPA/625/R-92/002, U.S. Envi-
     ronmental Protection Agency, May 1992.
 5.   Geosafe Corporation. Application and Evaluation Con-
     siderations for In Situ Vitrification Technology: A Treat
     ment Process for Destruction and/or Permanent
     Immobilization of Hazardous Materials.  April 1989
 6.   Technology Screening Guide for Treatment of CERCLA
     Soils and Sludges. EPA/540/2-88/004, U.S. Environmen-
     tal Protection Agency, 1988.  pp.  55-60.
 7.   FitzPatrick, V.F., and j.E. Hansen. In Situ Vitrification for
     Remediation of Hazardous Wastes.  Presented at 2nd
     Annual HazMat Central  Conference, Chicago Illinois
     1989.

 8.   Farnsworth, R.K., K.H. Orna, and C.E, Bigelow.  Initial
     Tests on In Situ Vitrification Using Electrode Feeding
     Techniques. Prepared for the U.S. Department of Ener-
     gy, under Contract DE-AC06-76RLO 1830, 1990,
9.   In Situ Vitrification Technology Update.  Geosafe Corpo
     ration. November 1992.
10.   Hansen, J.E., C.L Timmerman, and S.C.  Liikala. Status
    of In Situ Vitrification Technology:  A Treatment Process
    for Destruction and/or Permanent Immobilization. In:
    Proceedings of Annual HazMat Management Confer-
    ence International, Atlantic City, New Jersey,  1990 pp
    317-330.

11.  Greene, J.C., et al.  Comparison of Toxicity Results Ob-
    tained from Eluates Prepared from Non-Stabilized and
 12.
13.
     Stabilized Waste Site Soils.  In: Proceedings of the 5th
     National Conference on Hazardous Wastes and Hazard-
     ous Materials, Las Vegas, Nevada, 1988. pp. 77-80.
     FitzPatrick, V.F., C.L Timmerman, and J.L Buelt.  In Situ
     Vitrification - An Innovative Thermal Treatment Technol-
     ogy. Proceedings: Second International Conference on
     New Frontiers for Hazardous Waste Management. EPA/
     600/9-87/018F, U.S. Environmental Protection Agency
     1987. pp. 305-322.
     Timmerman, C.L. In Situ Vitrification Of PCB Contami-
     nated Soils. EPRI CS-4839. Electric Power Research Insti-
     tute, Palo Alto, California, 1986.
 14. Timmerman, C.L. Feasibility Testing of In Situ Vitrifica-
     tion of PCB-Contarninated Soil from a Spokane, WA
     Site.  Prepared for Geosafe Corporation, Kirkland, Wash-
     ington, under Contract 14506, 1989.
     Koegler, S.S. Disposal of Hazardous Wastes by In  Situ
     Vitrification. Prepared for the  U.S. Department of En-
     ergy, under Contract DE-AC06-76RLO 1830, 1987.
     Farnsworth, R.K., et  al.  Engineering-Scale Test: No, 4: In
     Situ Vitrification of Toxic Metals and Volatile Organics
     Buried in INEL Soils.  Prepared for the U.S. Department
     of Energy, under Contract DE-AC06-76RLO  1830, 1991.
 17.  Mitchell, S.j. In Situ Vitrification of Dioxin Contaminat-
     ed Soils.  Prepared for American Fuel and Power Corpo-
     ration, Panama City, Florida, under Contract
     2311211874, 1987.

 18.  Buelt, J.L., and ST. Freim. Demonstration of In Situ Vit-
     rification for Volume Reduction of Zirconia/Lime Slud-
     ges. Prepared for Teledyne Wah Chang, Albany,
     Oregon, under Contract 2311205327, 1986.
 19.  Timmerman, C.L. Feasibility Testing of In Situ Vitrifica-
     tion of Arnold Engineering Development Center Con-
     taminated Soils. Prepared for the U.S. Department of
     Energy, under Subcontract DE-AC05-84OR21400,  1989.
20. Correspondence from Geosafe Corp. to Mr. Edward R.
    Bates (RREL), September 17, 1991.
15.
16.
   United States
   Environmental Protection Agency
   Center for Environmental Research Information
   Cincinnati, OH 45268
  Official Business
  Penalty for Private Use
  $300
                                  BULK RATE
                            POSTAGE & FEES PAID
                                      EPA
                               PERMIT No. G-35
  EPA/540/S-94/504

-------