vvEPA
                           United States
                           Environmental Protection
                           Agency
                           Office of Emergency and
                           Remedial Response
                           Washington, DC 20460
Office of
Research
Cincinnati, OH 45268
                           Superfiind
                           EPA/540/2-91/006
May 1991
Engineering Bulletin
In  Situ  Soil  Vapor  Extraction
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 in
which treatment "permanently and significantly reduces the
volume, toxicity, or mobility of hazardous substances, pollut-
ants, and contaminants as a principal element." The Engi-
neering Bulletins are a series of  documents that summarize
the latest information available on selected treatment and site
remediation technologies and related issues.  They provide
summaries of and references for the latest information to help
remedial project managers, on-scene coordinators, contrac-
tors, and other site cleanup managers understand the type of
data and site characteristics needed to evaluate a technology
for potential applicability to their Superfund or other hazard-
ous waste site.  Those documents thtit describe individual
treatment technologies focus on remedial scoping  needs.
Addenda will  be issued periodically to update the original
bulletins.
Abstract

    Soil vapor extraction (SVE) is designed to physically re-
move volatile compounds, generally from the vadose or un-
saturated  zone.  It is an in situ process  employing vapor
extraction wells alone or in combination  with air injection
wells. Vacuum blowers supply the motive force, inducing air
flow through the soil matrix. The air strips the volatile com-
pounds from the soil and carries them to the screened ex-
traction well.

    Air emissions from the systems are typically controlled by
adsorption of the volatiles onto activated  carbon,  thermal
destruction (incineration or catalytic oxidation), or condensa-
tion by refrigeration [1, p. 26].*

    SVE is a developed technology that has been  used in
commercial operations for several years. It was the selected
remedy for the first Record of Decision (ROD) to be signed
under the Superfund Amendments and Reauthorization Act
of 1986 (the Verona Well Field Superfund Site in Battle Creek,

* [reference number, page number]
                             Michigan). SVE has been chosen as a component of the ROD
                             at over 30 Superfund sites [2] [3] [4] [5] [6].

                                 Site-specific treatability studies are the only means of
                             documenting the  applicability and performance  of an SVE
                             system. 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 treatability studies.

                                 The final determination of the lowest cost alternative will
                             be more site-specific than  process equipment dominated.
                             This bulletin provides information on the technology applica-
                             bility, the limitations of the technology, the technology de-
                             scription, the types of residuals produced, site requirements,
                             the latest performance data, the status of the technology, and
                             sources for further information.
                             Technology Applicability

                                 In situ SVE has been demonstrated effective for removing
                             volatile organic compounds (VOCs) from the vadose zone.
                             The effective removal of a chemical at a  particular site does
                             not, however,  guarantee an acceptable removal  level at all
                             sites. The technology is very site-specific. It must be applied
                             only after the  site has been characterized.  In general, the
                             process works  best in well  drained soils with low organic
                             carbon content. However, the technology has been shown to
                             work in finer, wetter soils (e.g., clays), but at much slower
                             removal rates [7, p. 5].

                                 The extent to which VOCs are dispersed in the soil—
                             vertically and horizontally—is an important consideration in
                             deciding whether SVE is preferable to other methods. Soil
                             excavation and treatment may be more cost effective when
                             only a few hundred cubic yards of near-surface soils have
                             been contaminated. If volume is in excess of 500 cubic yards,
                             if the spill has  penetrated more than 20 or 30 feet, or the
                             contamination  has spread through an area of several hundred
                             square feet at a particular depth, then excavation costs begin
                             to exceed  those  associated with  an SVE system [8]  [9]
                             [10, p. 6].

                                 The depth  to groundwater is also important.  Groundwa-
                             ter level in some cases may be lowered to increase the volume
                             of the unsaturated zone.  The water infiltration rate can be
                                                                                      Printed on Recycled Paper

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                        Table 1
            Effectiveness of SVE on General
             Contaminant Groups For Soil
Contaminant Croups



X
|
°





§
i


1
1
Halogenated volatiles
Halogenated semivolatiles
Nonhalogenated volatiles
Nonhalogenated semivolatiles
PCBs
Pesticides
Dioxins/Furans
Organic cyanides
Organic corrosives
Volatile metals
Nonvolatile metals
Asbestos
Radioactive materials
Inorganic corrosives
Inorganic cyanides
Oxidizers
Reducers
Effectiveness
Soil
m
T
•
•
a
a
a
a
a
a
a
a
a
a
a
a
T
• Demonstrated Effectiveness: Successful treatability test at some
scale completed
T Potential Effectiveness: Expert opinion that technology will work
LI No Expected Effectiveness: Expert opinion that technology will not
work
controlled by placing an impermeable cap over the site.  Soil
heterogeneities influence air movement as well as the loca-
tion of chemicals. The presence of heterogeneities may make
it more difficult to position extraction and inlet wells.  There
generally will be significant differences in the air permeability
of the various soil strata which will affect the optimum design
of the SVE facility.  The location of the contaminant on a
property and the type  and extent of development  in  the
vicinity of the contamination may favor the installation of an
SVE system.  For example, if the contamination exists beneath
a building or beneath an extensive utility trench network,  SVE
should be considered.

    SVE can be used alone or in combination with other
technologies to treat  a site.   SVE,  in  combination with
groundwater pumping and air stripping, is necessary when
contamination has reached an aquifer. When the contamina-
tion has  not penetrated into  the zone  of saturation (i.e.,
below the water table), it is not necessary to install a ground-
water pumping system.  A vacuum extraction well will cause
the water table  to rise and will saturate the soil in the area of
the contamination. Pumping is then required to draw the  wa-
ter table down and allow efficient vapor venting [11, p. 169].
     SVE may be used at sites not requiring complete remedia-
tion. For example, a site may contain VOCs and nonvolatile
contaminants.  A treatment requiring excavation might be
selected for the nonvolatile contaminants. If the site required
excavation in an enclosure to protect a nearby populace from
VOC emissions, it would be cost effective to extract the volatiles
from the soil  before excavation.  This would obviate the need
for the enclosure.  In this case it would be necessary to vent
the soil for only a fraction of the time required for complete
remediation.

     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
characterization of the site and a well-designed and conducted
treatability study are highly recommended.

     The effectiveness of SVE on  general contaminant groups
for soils is shown in Table 1.  Examples of constituents within
contaminant  groups are provided in the "Technology Screen-
ing Guide For Treatment of CERCLA Soils and  Sludges" [12].
This table  is  based on the 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 efficiencies achieved will be  acceptable at
other sites. For the ratings used in this table,  demonstrated
effectiveness means that, at some scale, treatability tests showed
that the technology was effective for that particular contami-
nant and matrix. The  ratings of potential effectiveness, or no
expected effectiveness are both based upon expert judgment.
Where potential effectiveness  is  indicated, the technology is
believed capable of successfully treating the contaminant group
in a particular matrix.  When the technology is not applicable
or will  probably not work for a  particular combination of
contaminant  group and matrix, a no-expected-effectiveness
rating is given. Another source of general observations and
average removal efficiencies for different treatability groups is
contained in  the Superfund Land Disposal Restrictions (LDR)
Guide #6A, "Obtaining a Soil and Debris Treatability Variance
for Remedial  Actions," (OSWER Directive 9347.3-06FS,  July
1989) [13]  and Superfund LDR Guide #6B, "Obtaining a Soil
and Debris Treatability Variance for Removal Actions," (OSWER
Directive 9347.3-07FS,  December 1989) [14].
Limitations

    Soils exhibiting low air permeability are more difficult to
treat with in situ  SVE.   Soils  with  a high organic carbon
content have a high sorption capacity for VOCs and are more
difficult to remediate successfully with SVE.  Low soil tem-
perature lowers a contaminant's vapor pressure,  making vola-
tilization more difficult [11].

    Sites that contain a high degree of soil heterogeneity will
likely offer variable flow and desorption performance, which
will make remediation difficult.  However,  proper design of
the vacuum extraction system may overcome the problems of
heterogeneity [7, p. 19] [15].
                                               Engineering Bulletin: In Situ Soil Vapor Extraction Treatment

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    It would  be difficult to remove soil contaminants with
low vapor pressures and/or high water solubilities from a site.
The lower limit of vapor pressure for  effective removal of a
compound  is  1  mm Hg abs.  Compounds with high water
solubilities,  such as acetone, may be  removed with relative
ease from arid soils. However, with normal soils (i.e.,  mois-
ture content  ranging from  10 percent to 20 percent), the
likelihood of  successful remediation drops significantly be-
cause the moisture in  the soil acts as a sink for the soluble
acetone.
Technology Description

    Figure 1 is a general schematic of the in situ SVE process.
After the contaminated area  is defined, extraction wells (1)
are installed.  Extraction well  placement is critical.  Locations
must be chosen to ensure adequate vapor flow through the
contaminated  zone while  minimizing  vapor flow  through
other zones [11,  p. 170].  Wells are typically constructed of
PVC pipe that is screened through the zone of contamination
[11 ]. The screened pipe is placed in a permeable packing; the
unscreened portion is sealed in a cement/bentonite grout to
prevent a short-circuited air flow direct to the surface. Some
SVE systems are installed with air injection wells.  These wells
may either  passively take in atmospheric air or  actively use
forced air injection [9]. The system must be designed so that
any air injected into the system does not result in the escape
of VOCs to the atmosphere.  Proper design of the system can
also  prevent offsite contamination  from entering the  area
being extracted.

    The physical dimensions  of a particular site may modify
SVE design. If the vadose zone depth is less than 10 feet and
the area of the site is quite large, a horizontal piping system or
trenches may be more economical than conventional wells.
    An  induced air flow draws contaminated vapors  and
entrained water from the extraction wells through headers—
usually plastic piping—to a vapor-liquid separator (2). There,
entrained water is separated and contained for subsequent
treatment (4).  The contaminant vapors  are  moved  by a
vacuum blower (3) to vapor treatment (5).

    Vapors produced by the process are typically treated by
carbon adsorption or thermal destruction.  Other methods—
such as condensation, biological degradation, and ultraviolet
oxidation—have been applied, but only to a limited extent.
Process Residuals

    The waste streams generated by in situ SVE are vapor and
liquid treatment residuals (e.g., spent granular activated car-
bon [GAC]), contaminated groundwater, and soil tailings from
drilling the wells.  Contaminated groundwater may be treated
and discharged onsite [12, p. 86] or collected and treated off-
site.  Highly contaminated soil tailings from drilling must be
collected and may be either cleaned onsite or sent to an
offsite, permitted facility for treatment by another technology
such as incineration.
Site Requirements

    SVE systems vary in size and complexity depending on
the capacity of the system and  the requirements for vapor
and liquid treatment. They are typically transported by vehicles
ranging from trucks to specifically adapted flatbed semitrailers;
therefore, a proper staging  area for these vehicles must be
incorporated in the plans.
                                                      Figure 1
                            Process Schematic of the In Situ Soil Vapor Extraction System
                                                                                          Clean Air
i
Extraction
Well
(1)
Air Vent or
Injection Well
\



r
Extracted u___, L
Viioor Vapor- •
vapor __ , |nii,H •]
t



1
(2) [ Separator J
f «
Air Vent or
Injection Well
Ground Surface
Contaminated
Vadose
Zone
r
™ ^-
Process Residual
V Liquid b CleanWater

Treatment • ^
y Process Residual^

Monitoring
Well
                                                   Water Table
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment

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    Adequate access roads must be provided to bring mobile
drilling  rigs onsite for  construction of wells  and to deliver
equipment required for the  process (e.g., vacuum blowers,
vapor-liquid separator, emission control devices, GAC canisters).

    A small commercial-size  SVE system would require about
1,000 square feet of ground area for the equipment.  This
area does not include space for the monitoring wells which
might cover 500 square feet.  Space may be needed for a
forklift truck to exchange skid-mounted GAC  canisters when
regeneration is required. Large systems with integrated vapor
and liquid treatment systems will need additional area based
on vendor-specific requirements.

    Standard 440V, three-phase electrical service is needed.
For many SVE applications, water may be  required at the site.
The quantity of water needed is vendor- and site-specific.

    Contaminated soils or other waste materials are hazard-
ous, and their handling requires that a  site  safety plan  be
developed  to  provide for personnel protection and  special
handling measures.  Storage should be provided to hold the
process  product streams until they have been tested to deter-
mine  their  acceptability for disposal or release.  Depending
upon  the site, a method to store soil tailings  from  drilling
operations  may be necessary. Storage capacity will depend
on waste volume.

    Onsite analytical equipment,  including gas chromato-
graphs and organic vapor analyzers capable of determining
site-specific organic compounds for performance assessment,
make the operation more efficient and provide better infor-
mation for process control.


Performance  Data

    SVE, as an in situ process  (no excavation is  involved), may
require treatment of the soil to various cleanup levels man-
dated by federal and state  site-specific  criteria.  The time
required to meet a  target cleanup level (or performance ob-
jective) may be estimated by using data obtained from  bench-
                                scale and pilot-scale tests in a time-predicting mathematical
                                model.  Mathematical models can estimate cleanup time to
                                reach a target level, residual contaminant levels after a given
                                period of operation and  can  predict location of hot spots
                                through diagrams of contaminant distribution [16].

                                    Table 2 shows the performance of typical SVE applica-
                                tions. It lists the site location and size, the contaminants and
                                quantity of contaminants removed, the duration of operation,
                                and the maximum soil contaminant concentrations  before
                                treatment and after treatment.  The data presented for specific
                                contaminant removal  effectiveness were obtained,  for the
                                most part, from publications developed by the respective SVE
                                system vendors. The quality of this information has not been
                                determined.

                                    Midwest  Water  Resources,  Inc. (MWRI) installed its
                                VAPORTECH™  pumping unit at the Dayton, Ohio site of a
                                spill of uncombusted paint solvents caused by a fire in a paint
                                warehouse [19]. The major VOC compounds identified were
                                acetone, methyl isobutyl ketone (MIBK), methyl ethyl ketone
                                (MEK), benzene, ethylbenzene, toluene, naphtha, xylene, and
                                other volatile aliphatic and alkyl benzene compounds.  The
                                site  is underlain predominantly by valley-fill glacial outwash
                                within the Great Miami River Valley, reaching a thickness of
                                over 200 feet.  The outwash is composed chiefly of coarse,
                                clean sand and gravel, with numerous cobbles and small
                                boulders. There are two outwash units at the site separated
                                by a discontinuous till at depths of 65 to 75 feet.  The upper
                                outwash forms an unconfined aquifer  with saturation at a
                                depth of 45 to 50 feet below grade. The till below serves as
                                an aquitard between the upper unconfined aquifer and the
                                lower confined to semiconfined aquifer. Vacuum withdrawal
                                extended to the depth of groundwater at about 40 to 45 feet.
                                During  the first 73 days  of operation, the system yielded
                                3,720 pounds of volatiles and after 56 weeks of operation,
                                had  recovered  over 8,000 pounds of VOCs from the site.
                                Closure levels for the site were developed for groundwater
                                VOC levels of ketones only. These soil action levels (acetone,
                                810  u.g/1; MIBK, 260 u.g/1, and MEK, 450 ng/l) were set so that
                                waters recharging through contaminated soils would result in
                                                      Table 2.
                            Summary of Performance Data for In Situ Soil Vapor Extraction
 Sfte_	      	
 Industrial - CA [1 7]
 Sheet Metal Plant - Ml [18]
 Prison Const. Site- Ml [19]
 Sherwin-Williams Site - OH [19]
 Upjohn- PR [20][21]
 UST Bellview - FL [7]
 Verona Wellfield - Ml [7][22]
 Petroleum Terminal -
 Owensboro, KY [19]
 SITE Program - Groveland MA [7]
	Size	


    5,000 cu yds
  165,000 cu yds
  425,000 cu yds
 7,000,000 cu yds


   35,000 cu yds
   12,000 cu yds

    6,000 cu yds
 Contaminants

     TCE

     PCE*

     TCA

 Paint solvents

     CCI4

     BTEX

TCE, PCE, TCA
Gasoline, diesel


     TCE
Quantity
removed
30kg
59kg
~
4,100kg
7,000 kg
?,700 kg
2,700 kg
...
Duration of
operation
440 days
35 days
90 days
6 mo
3yr
7 mo
Over 1 yr
6 mo
Soil concentrations (mg/kg)
max. before after
treatment treatment
0.53
5600
3.7
38
2200
97
1380
>5000
0.06
0.70
0.01
0.04
<0.005
<0.006
Ongoing
1 .0 (target)
                  590kg
56 days
                                                                                              96.1
                                                                                                          4.19
    *PCE = Perchloroethylene
                                              Engineering Bulletin: In Situ Soil Vapor Extraction Treatment

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groundwater VOC  concentrations at or below  regulatory
standards. The site met all the closure criteria by June 1988.

    A limited amount of performance data is available from
Superfund sites.  The EPA  Superfund  Innovative Technology
Evaluation (SITE) Program's Groveland, Massachusetts, dem-
onstration of the Terra Vac Corporation SVE process produced
data that were subjected to quality assurance/quality control
tests. These data appear in Table 2 [7, p. 29] and Table 3 [7,
p. 31]. The site is contaminated by trichloroethylene (TCE), a
degreasing compound  which was used by a machine shop
that is still in operation.  The subsurface profile in the test area
consists of medium sand and gravel just below the surface,
underlain by finer and silty sands, a clay layer 3 to 7 feet in
depth, and—below the clay layer—coarser sands with gravel.
The clay layer or lens acts as a barrier against gross infiltration
of VOCs into subsequent subsoil strata.  Most of the subsur-
face contamination lay above the clay lens, with the highest
concentrations adjacent to it.  The SITE data  represent the
highest percentage of contaminant reduction from one of the
four extraction wells installed for this demonstration test. The
TCE concentration levels are weighted average soil concen-
trations obtained by averaging split spoon sample concentra-
tions every  2  feet over the entire 24-foot extraction well
depth. Table 3 shows the  reduction of TCE in the soil strata
near the same extraction well. The Groveland Superfund Site
is in the process of being  remediated using this technology
[2].

    The Upjohn facility in Barceloneta, Puerto Rico, is the first
and, thus far, the only Superfund site  to be remediated with
SVE. The contaminant removed from this site was a mixture
containing  65 percent  carbon tetrachloride (CCI4) and 35
percent acetonitrile [20]. Nearly 18,000 gallons of CCI4 were
extracted during the remediation, including 8,000 gallons
that were extracted during a pilot operation conducted from
January 1983 to April 1984. The volume of soil treated at the
Upjohn site amounted to 7,000,000 cubic yards. The respon-
sible party originally argued that the site should be considered
                                             clean when soil samples taken from four boreholes drilled in
                                             the area of high pretest contamination show nondetectable
                                             levels of CCI4. EPA did not accept this criterion but instead
                                             required a cleanup criteria of nondetectable levels of CCI4 in all
                                             the exhaust stacks for 3 consecutive  months [21].  This re-
                                             quirement was met by the technology and the site was con-
                                             sidered remediated by EPA.

                                                 Approximately 92,000 pounds of contaminants have been
                                             recovered from the Tyson's Dump site (Region 3) between
                                             November 1988  and July 1990.   The site consists of  two
                                             unlined lagoons and surrounding areas formerly used to store
                                             chemical wastes.  The initial Remedial Investigation identified
                                             no soil heterogeneities and indicated that the water table was
                                             20 feet below the surface.  The maximum concentration in
                                             the soil  (total VOCs) was approximately 4 percent.   The
                                             occurence of dense nonaqueous-phase liquids (DNAPLs)  was
                                             limited in areal extent.  After over 18 months of operation, a
                                             number of difficulties have been encountered.  Heterogene-
                                             ities  in soil grain  size, water content, permeability,  physical
                                             structure and compaction, and in contaminant concentrations
                                             have been  identified. Soil contaminant concentrations of up
                                             to 20 percent and widespread distribution of  DNAPLs have
                                             been found. A tar-like substance, which has caused plugging,
                                             has been found  in  most of  the extraction  wells.  After 18
                                             months of  operation, wellhead concentrations  of total VOCs
                                             have decreased by greater than 90 percent [23, p. 28].

                                                 As of December 31,1990, approximately 45,000 pounds
                                             of VOCs had been  removed from the Thomas Solvent Raymond
                                             Road Operable Unit at the Verona Well Field site (Region 5). A
                                             pilot-scale system  was tested in the fall of 1987 and a full-scale
                                             operation began in March, 1988. The soil at the site consists
                                             of poorly-graded,  fine-to-medium-grained loamy soils under-
                                             lain by approximately 100 feet of sandstone. Groundwater is
                                             located 16 to 25 feet below the surface.  Total  VOC concen-
                                             trations in  the combined  extraction  well header have  de-
                                             creased from a high of 19,000 ug/1  in 1987 to approximately
                                             1,500ug/1 in 1990 [22].
                                                      Table 3
           Extraction Well 4: TCE Reduction In Soil Strata—EPA Site Demonstration (Groveland, MA) [7, p. 31]
   Depth (ft)
Description of strata
     0-2        Med. sand w/gravel
     2-4        Lt. brown fine sand
     4-6        Med. stiff It. brown fine sand
     6-8        Soft dk. brown fine sand
     8-10       Med. stiff brown sand
     10-12       V. stff It. brown med. sand
     12-14       V. Stiff brown fine sand w/silt
     14-16       M. stff grn-brn clay w/silt
     16-18       Soft wet clay
     18-20       Soft wet clay
     20-22       V. stiff brn mecl-coarse sand
     22-24       V. stiff brn mecl-coarse w/gravel
Hydraulic
Conductivity (cm/s)
10-4
lO^1
10s
10s
10^
10^
10-4
10-"
io-8
10-8
io-4
103
Soil TCE concentration (mg/kg)
Pre-treatment Post-treatment
2.94
29.90
260.0
303.0
351.0
195.0
3.14
ND
ND
ND
ND
6.17
ND
ND
39.0
9.0
ND
ND
2.3
ND
ND
ND
ND
ND
     ND - Nondetectable level
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment

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     An SVE pilot study has been completed at the Colorado
 Avenue Subsite of the Hastings (Nebraska) Groundwater Con-
 tamination site (Region 7).  Trichloroethylene (TCE), 1,1,1-
 trichloroethane (TCA), and tetrachloroethylene (PCE) occur in
 two distinct unsaturated soil zones. The shallow zone, from
 the surface to a depth of 50 to 60 feet, consists of sandy and
 clayey silt. TCE concentrations as high as 3,600 ug/1 were
 reported by EPA in this soil zone. The deeper zone consists of
 interbedded sands, silty sands, and gravelly sands extending
 from about 50 feet to 120 feet.  During the first 630 hours of
 the pilot study (completed October 11,1989),  removal  of
 approximately 1,488 pounds of VOCs  from a  deep zone
 extraction well and approximately 127 pounds of VOCs from
 a shallow zone extraction well were reported.   The data
 suggest that SVE is a viable remedial technology for both soil
 zones [24].

     As of November, 1989, the SVE system at the Fairchild
 Semi-conductor Corporation's former San Jose site (Region 9)
 has reportedly removed over 14,000 pounds of volatile con-
 taminants. Total contaminant mass removal rates for the SVE
 system fell below 10 pounds per day on October 5, 1989 and
 fell below 6 pounds per day in December, 1989. At that time,
 a proposal to terminate operation  of the SVE system was
 submitted to the Regional Water Quality Control Board for
 the San Francisco Bay Region [25, p.3].

     Resource  Conservation and  Recover/ Act (RCRA) LDRs
 that require treatment of wastes to best demonstrated avail-
 able technology (BOAT) level:,  prior to land  disposal may
 sometimes be determined to be applicable or relevant and
 appropriate requirements for CERCLA response actions. SVE
 can produce a treated waste that meets treatment levels set
 by BOAT but may not reach these treatment levels in all cases.
 The ability to  meet required treatment levels is dependent
 upon the specific waste constituents and the waste matrix. In
 cases where SVE does not meet these levels, it still may, in
 certain situations, be selected for use at the site if a treatability
 variance establishing alternative treatment levels is obtained.
 EPA has made the treatability variance process available in
 order to ensure that LDRs do not unnecessarily restrict use of
 alternative and innovative treatment technologies. Treatabil-
 ity variances are justified for handling complex soil and debris
 matrices.  The following guides describe when and how to
 seek a treatability variance for soil and debris: Superfund LDR
 Guide #6A, "Obtaining a Soil arid Debris Treatability Variance
 for Remedial  Actions" (OSWER  Directive  9347.3-06FS, July
 1989) [1 3], and Superfund LDR Guide #6B, "Obtaining a Soil
 and Debris Treatability Variance for Removal Actions" (OSWER
 Directive 9347.3-07FS, December 1989)  [14].  Another ap-
 proach could be to use other treatment techniques in series
 with SVE to obtain desired treatment levels.

Technology Status

    During 1989, at least 1 7 RODs specified SVE as part of
the remedial action [5]. Since 1982, SVE has been selected as
the remedial action, either alone or in conjunction with other
treatment technologies, in more than 30 RODs for Superfund
sites [2] [3] [4]  [5] [6].  Table 4 presents the location, primary
 contaminants,  and status for  these sites [3]  [4] [5].  The
 technology also has been used to clean up numerous under-
 ground gasoline storage tank spills.

     A number of variations  of the SVE  system have been
 investigated at Superfund sites.  At the Tinkhams Garage Site
 in New  Hampshire (Region 1), a pilot study indicated that
 SVE, when used in conjunction  with ground  water pumping
 (dual extraction), was capable of treating soils to the 1 ppm
 clean-up goal [26, 3-7] [27].  Soil dewatering studies have
 been conducted to determine the feasability  of lowering the
 water table to  permit the use of SVE at the  Bendix, PA Site
 (Region  3) [28]. Plans are underway to remediate a stockpile
 of 700 cubic yards of excavated soil at the Sodeyco Site in Mt.
 Holly, NC using SVE [29].

     With the exception of the Barceloneta site, no Superfund
 site has yet been cleaned up to the performance objective of
 the technology. The performance objective  is a site-specific
 contaminant concentration, usually in soil. This objective may
 be  calculated with mathematical models with which EPA
 evaluates delisting petitions for wastes  contaminated with
 VOCs [30].  It also may be possible to use a TCLP test on the
 treated soil with a  corresponding drinking  water standard
 contaminant level on the leachate.

     Most of the hardware components of SVE are available
 off the shelf and represent  no significant problems of avail-
 ability.  The configuration,  layout, operation, and design of
 the extraction and monitoring wells and process components
 are site specific. Modifications may also be required as dic-
 tated by  actual operating conditions.

    On-line availability of the full-scale systems described in
 this  bulletin is  not documented.  System components are
 highly reliable and are capable  of continuous operation for
 the duration of the cleanup. The system can be shut down, if
 necessary, so that component failure can be identified and
 replacemnts made quickly for minimal downtime.

    Based  on available  data, SVE treatment estimates are
 typically  $50/ton for  treatment of soil.  Costs range from as
 low as $10/ton to as much as  $150/ton [7]. Capital costs for
 SVE consist of extraction  and monitoring well construction;
 vacuum blowers (positive displacement or centrifugal); vapor
 and liquid treatment systems piping, valves, and  fittings (usu-
 ally plastic); and instrumentation [31]. Operations and main-
 tenance costs include labor, power, maintenance, and moni-
 toring activities. Offgas and collected groundwater treatment
 are the largest cost items in this list; the cost of a cleanup can
 double if both  are treated  with activated carbon.   Electric
 power costs vary by location (i.e., local utility rates and site
 conditions).  They may be as low as 1 percent or as high as 2
 percent of the total project cost.

    Caution is  recommended in  using these costs  out of
context, because the  base year of the estimates vary.  Costs
also are highly variable due to site variations as  well as soil and
contaminant characteristics that  impact the SVE process. As
contaminant concentrations are  reduced, the cost effective-
ness of an SVE system may decrease with time.
                                              Engineering Bulletin: In Situ Soil Vapor Extraction Treatment

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                                                             Table 4
                                     Superfund Sites Specifying SVE as a Remedial Action
         Site
                               Location (Region)
                             Primary Contaminants
                                              Status
 Groveland Weils 1 & 2

 Kellogg-Deering Well Field
 South Municipal Water
   Supply Well
 Tinkham Garage
 Wells G & H
 FAA Technical Center
 Upjohn Manufacturing Co.
 Allied Signal Aerospace-
   Bendix Flight System Div.
 Henderson Road

 Tyson's Dump

 Stauffer Chemical
 Stauffer Chemical
 Sodyeco
 Kysor Industrial

 Long Prairie

 MIDCO 1
 Miami County Incinerator
 Pristine

 Seymour Recycling
Verona Well Field
Wausau Groundwater
   Contamination
South Valley/
   General Electric
Hastings Groundwater
   Contamination

Sand Creek Industrial
Fairchild Semiconductor
Fairchild Semiconductor/
   MTV-1

Fairchild Semiconductor/
   MTV-2

Intel Corporation
Raytheon Corporation
Motorola 52nd Street
Phoenix-Goodyear Airport
Area (also Litchfield
Airport Area)	
 Croveland,
 Morwalk, CT (1 )
 Peterborough, NH(1)

 Londonderry, NH (1)
 Woburn, MA(1)
 Atlantic County, Nj (2)
 Barceloneta, PR (2)
 South Montrose, PA (3)

 Upper Merion Township,
 PA (3)
 Upper Merion Township,
 PA (3)
 Cold Creek, AL (4)
 Lemoyne, AL (4)
 Mt. Holly, NC (4)
 Cadillac, Ml (5)

 Long Prairie, MN (5)

 Gary,  IN (5)
Troy, OH (5)
Cincinnati, OH (5)

Seymour, IN (5)
Battle Creek, Ml (5)
Wausau, Wl (5)

Albuquerque, NM (6)

Hastings, NE (7)
Commerce City, CO (8)
San Jose, CA (9)
Mountain View, CA (9)
Mountain View, CA (9)
Mountain View, CA (9)
Mountain View, CA (9)
Phoenix, A2 (9)
GxxJyear, AZ (9)
 TCE

 PCE, TCE, and BTX
 PCE, TCE, Toluene

 PCE, TCE
 PCE, TCE
 BTX, PAHs, Phenols
 CCI4
 TCE

 PCE, TCE, Toluene, Benzene

 PCE, TCE, Toluene, Benzene,
 Trichloropropane
 CCL4, pesticides
 CCL4, pesticides
 TCE, PAHs
 PCE, TCE,Toluene, Xylene

 PCE, TCE, DCE, Vinyl chloride

 BTX, TCE, Phenol, Dichloro-
 methane,  2-Butanone,
 Chlorobenzene
 PCE; TCE; Toluene
 Benzene; Chloroform; TCE;
 1,2-DCA; 1,2-DCE
 TCE; Toluene; Chloromethane;
 cis-1, 2-DCE; 1,1,1 -DCA;
 Chloroform
 PCE, TCA
 PCE, TCE

 Chlorinated solvents

 CCL4 ,Chloroform
PCE, TCE, pesticides
PCE, TCA, DCE, DCA,
Vinyl chlorides, Phenols,
and Freon
PCE, TCA, DCE, DCA,
Vinyl chlorides, Phenols,
and Freon
PCE, TCA, DCE, DCA,
Vinyl chlorides, Phenols,
and Freon
PCE, TCA, DCE, DCA,
Vinyl chlorides, Phenols,
and Freon
PCE, TCA, DCE, DCA,
Vinyl chlorides, Phenols,
and Freon
TCA, TCE, CCL4 , Ethylbenzene
TCE, DCE, MEK
 SfTE demonstration complete            [2][7]
 Full-scale Remediation in design
 Pre-design                        [3] [5] [6]
 Pre-design completion expected in the fail
 of 1991
 Pre-design pilot study completed
 In design
 In design
 Project completed in 1988
 Pre-design tests and dewatering
 study completed
 Pre-design

 In operation (since 11 /88)                [23]

 Pre-design                           [5] [6]
 Pre-design                           [5] [6]
 Design approved                        [29]
 In design; pilot studies in progress    [3] [5] [6]

 SVE construction expected in the Fall of 1991
                                     [3H6J
 In Design                          [3] [5] [6]
Pre-design                         [3] [5] [6]
Pre-design                            [3] [6]

Pre-design investigation completed        [32]
Operational since 3/81                   [22]
Pre-design                         [3] [5] [6]

Pilot studies scheduled for              [4] [6]
Summer of 1991
Pilot studies completed for                [24]
Colorado Ave. fit Far-Marco
subsites
Pilot study completed                    [33]
Operational since 1988,                  [25]
Currently conducting
resaturation studies
Pre-design                            [3] [5]
Pre-design                            [3] [5]


Pre-design                            [3] [5]


Pre-design                            [3] [5]
Pre-design                        [3] [4] [6]
North Unit - In design                   [34]
South Unit - pilot study completed
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment

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EPA Contact

    Technology-specific questions regarding SVE may be di-
rected to:

    Michael Gruenfeld
    U.S. Environmental Protection Agency
    Releases Control Branch
    Risk Reduction Engineering Laboratory
    2890 Woodbridge Ave.
    Building 10(MS-104)
    Edison, NJ 08837
    (FTS) 340-6924 or (908) 321 -6924
Acknowledgements

    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), and
               Foster Wheeler Enviresponse Inc. (FWEI) under contract No.
               68-C8-0062.  Mr. Eugene Harris served as the EPA Technical
               Project Monitor.   Gary Baker was SAIC's Work Assignment
               Manager. This bulletin was authored by Mr. Pete Michaels of
               FWEI. The author is especially grateful to Mr. Bob Hillger and
               Mr. Chi-Yuan Fan of EPA, RREL, who have contributed signifi-
               cantly by serving as technical consultants during the devel-
               opment of this document.

                  The  following other Agency and contractor  personnel
               have contributed their time and comments by participating in
               the expert review meetings and/or peer reviewing  the docu-
               ment:
               Dr. David Wilson
               Dr. Neil Hutzler
               Mr. Seymour Rosenthal
               Mr. Jim Rawe
               Mr. Clyde Dial
               Mr. Joe Tillman
Vanderbilt University
Michigan Technological University
FWEI
SAIC
SAIC
SAIC
8
Engineering Bulletin: In Situ Soil Vapor Extraction Treatment

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Engineering Bulletin: In Situ Soil Vapor Extraction Treatment

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33. Groundwater Technology, Inc. Report of Findings -            34. Hydro Ceo Chem, Inc. Results and Interpretation of the
   Vacuum Extraction Pilot Treatability at the Sand Creek             Phoenix Goodyear Airport SVE Pilot Study, Goodyear,
   Superfund Site (OU-1), Commerce City, Colorado,                Arizona, May 1989.
   March 1990.
10                                          Engineering Bulletin: In Situ Soil Vapor Extraction Treatment
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