United States
                                Environmental Protection
                                Agency
     Office of
     Research and Development
     Cincinnati, OH 45268
EPA 540/R-94/529a
June 1995
                            SITE Technology Capsule
                            Subsurface  Volatilization  and
                            Ventilation  System  (SVVS)®
Abstract

      The Subsurface Volatilization and Ventilation System®
is an integrated technology used for attacking all phases of
volatile organic  compound (VOC) contamination in soil and
groundwater.  The  SVVS®  technology  promotes  insitu
remediation  of soil and  groundwater  contaminated with or-
ganic compounds through the injection of air into the satu-
rated and unsaturated zones, and extraction of vapors from
the vadose zone. Through this process, volatile and semivolatile
organic compounds are stripped from the soil and groundwa-
ter. The subsurface circulation of air also increases dissolved
oxygen concentrations in the saturated zone, capillary fringe,
and vadose  zone, thereby promoting aerobic microbiological
processes. The contaminated air extracted from the wells can
be treated at the surface before being  discharged  to the
environment.

     The SVVS® process was evaluated  under the SITE
program at the  EV facility in  Buchanan, Ml.  The soils were
contaminated with aromatic hydrocarbons, and halogenated
and non-halogenated volatile  and semivolatile organic com-
pounds (SVOCs) through discharge into a dry well. Baseline
data indicated that approximately 1,000 kg of VOC and SVOC
contamination was present in the dry well area soils,  princi-
pally in a subsurface sludge layer. The developer claimed that
their technology would reduce the sum of seven target VOCs
by 30% over a 1 -yr period.

     The results from the demonstration indicate the SVVS®
technology greatly exceeded their claims by providing a site
average 80.6%  reduction of volatile organics in  the vadose
zone. Furthermore, aerial and vertical  reductions across the
site did not indicate the presence of any zones that were not
treated  by the system.  The SVVS® process proved to be
reliable and required minimal operator oversight. The technol-
ogy did not experience significant operational difficulties dur-
ing the evaluation period.
      The SVVS®  remediation technology was  evaluated
based on seven criteria  used  for decision  making  in the
Superfund feasibility study (FS) process. Results of the evalu-
ation are summarized in Table 1.

Introduction

      In 1980, the  U.S. Congress passed the Comprehen-
sive  Environmental  Response,  Compensation,  and Liability
Act (CERCLA), also known as Superfund, committed to pro-
tecting human health and the environment from uncontrolled
hazardous waste sites. CERCLA was amended by the Super-
fund  Amendments and Reauthorization Act (SARA) in 1986.
These amendments emphasize the achievement of long-term
effectiveness and permanence of remedies at Superfund sites.
SARA mandates implementing permanent solutions and us-
ing alternative treatment technologies or resource recovery
technologies, to the maximum extent possible, to clean up
hazardous waste sites.

      State and federal agencies,  as well as private parties,
are now exploring a growing number of innovative technolo-
gies for treating hazardous wastes. The sites on the National
Priorities List total over 1,700 and  represent  a broad spec-
trum  of physical, chemical, and environmental conditions re-
quiring various types of remediation. The U.S. Environmental
Protection Agency (EPA)  has focused on  policy,  technical,
and informational issues  related to exploring  and applying
new remediation technologies to Superfund sites.  One such
initiative is EPA's Superfund Innovative Technology Evalua-
tion (SITE) program, which was  established to accelerate
development, demonstration, and use of innovative technolo-
gies for site cleanups. EPA SITE Technology Capsules sum-
marize the latest information available on selected innovative
treatment  and site remediation technologies and related is-
sues. These Capsules are designed to  help  EPA remedial
project managers, EPA on-scene  coordinators, contractors,
and other site  cleanup managers  understand the types  of
                                        SUPERFUND INNOVATIVE
                                        TECHNOLOGY EVALUATION
                                                                                    Printed on Recycled Paper

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     &EPA
                                United States
                                Environmental Protection
                                Agency
                               Office of
                               Research and Development
                               Cincinnati, OH 45268
EPA 540/R-94/529a
June 1995
SITE Technology Capsule
Subsurface  Volatilization  and
Ventilation  System  (SVVS)®
Abstract

      The Subsurface Volatilization and Ventilation System®
is an integrated technology used for attacking all phases of
volatile organic compound (VOC) contamination in soil and
groundwater.  The SVVS®  technology promotes  insitu
remediation  of soil  and groundwater contaminated with or-
ganic compounds through the injection of air into the satu-
rated and unsaturated zones, and extraction of vapors from
the vadose zone. Through this process, volatile and semivolatile
organic compounds are stripped from the soil and groundwa-
ter. The subsurface circulation of air also increases dissolved
oxygen concentrations in the saturated zone, capillary fringe,
and vadose  zone, thereby promoting aerobic microbiological
processes. The contaminated air extracted from the wells can
be treated at the  surface before being discharged to the
environment.

     The SVVS® process was evaluated under  the SITE
program at the EV  facility in  Buchanan, Ml. The soils were
contaminated with  aromatic hydrocarbons, and halogenated
and non-halogenated volatile  and semivolatile organic com-
pounds (SVOCs) through  discharge into a dry well. Baseline
data indicated that approximately 1,000 kg of VOC and SVOC
contamination was present in the dry well area soils, princi-
pally in a subsurface sludge layer. The developer claimed that
their technology would reduce the sum of seven target VOCs
by 30% over a 1 -yr period.

     The results from the demonstration indicate the SVVS®
technology greatly exceeded their claims by providing  a site
average 80.6% reduction  of volatile organics in the vadose
zone. Furthermore,  aerial  and vertical  reductions across the
site did not indicate the presence of any zones that were not
treated  by the system. The SVVS® process proved  to be
reliable and required minimal operator oversight. The technol-
ogy did not experience significant operational difficulties dur-
ing the evaluation period.
                                The SVVS® remediation technology was  evaluated
                           based on seven  criteria  used  for decision making in the
                           Superfund feasibility study (FS) process. Results of the evalu-
                           ation are summarized in Table 1.

                           Introduction

                                In 1980, the U.S. Congress passed the Comprehen-
                           sive  Environmental Response,  Compensation, and Liability
                           Act (CERCLA), also known as Superfund, committed to pro-
                           tecting human health and the environment from uncontrolled
                           hazardous waste sites. CERCLA was amended by the Super-
                           fund  Amendments and  Reauthorization Act (SARA) in 1986.
                           These amendments emphasize the achievement of long-term
                           effectiveness and permanence of remedies at Superfund sites.
                           SARA mandates implementing permanent solutions and us-
                           ing alternative treatment technologies or resource recovery
                           technologies,  to the maximum extent  possible, to clean up
                           hazardous waste sites.

                                State and federal agencies,  as well as private parties,
                           are now exploring  a growing number of innovative technolo-
                           gies for treating hazardous wastes. The sites on the National
                           Priorities List  total over 1,700 and  represent a broad spec-
                           trum  of physical, chemical, and environmental conditions re-
                           quiring various types of  remediation. The U.S. Environmental
                           Protection Agency (EPA)  has focused on  policy,  technical,
                           and informational  issues  related to exploring and applying
                           new remediation technologies to Superfund sites.  One such
                           initiative is EPA's Superfund Innovative Technology Evalua-
                           tion (SITE) program, which was  established to  accelerate
                           development,  demonstration, and use of innovative technolo-
                           gies for site cleanups. EPA SITE Technology Capsules sum-
                           marize the latest information available on selected innovative
                           treatment  and site remediation technologies and related is-
                           sues. These Capsules  are designed to  help  EPA remedial
                           project managers,  EPA on-scene  coordinators, contractors,
                           and other site cleanup managers  understand the types of
                                       SUPERFUND INNOVATIVE
                                       TECHNOLOGY EVALUATION
                                                                                   Printed on Recycled Paper

-------
Table 1. FS Criteria Evaluation For The SVVS® Technology
                                                        FS Criteria
Overall Protection
of Human Health
and the Environ-
ment
Provides both short-
and long-term pro-
tection by eliminating
organic contami-
nants in soil.
Compliance with
Federal ARARs
Requires compli-
ance with RCRA
treatment, storage,
and land disposal
regulations (of a
hazardous waste).
Long-Term
Effectiveness
and Permanence
Effectively removes
contamination
source.
Reduction of
Toxicity, Mobility,
or Volume Through
Treatment
Significantly reduces
toxicity, mobility, and
volume of soil contam-
inants through
treatment.
Short-Term
Effectiveness
Presents potential
short-term risks to
workers and com-
munity from vola-
tiles released
during system
installation.
Implementability
Involves few
administrative
difficulties.
Cost
$192,237 to clean
2 1,300 yd3 ($9/
yd3) over 3 yr
excluding effluent
treatment &
disposal
Prevents further
groundwater con-
tamination and
off-site migration.



Requires mea-
sures to protect
workers and com-
munity during
excavation, hand-
ling, and treatment.
Excavation, con-
struction and
operation of on-site
treatment unit may
require compliance
with location specific
ARARs.
Emission controls
may be needed to
ensure compliance
with air quality stand-
ards if VOCs are
present.
Involves well dem-
onstrated technique
for removal of con-
taminants.



Involves some
residuals treat-
ment, i.e.
extracted air
and minor soil
from installation.
                                                                                         System is easy to
                                                                                         install and operate.
                                             $356,737 ($16.75/
                                             yd3) including
                                             vapor phase GAC
                                             for effluent treat-
                                             ment & disposal
data and site characteristics needed to effectively evaluate a
technology's suitability for cleaning up Superfund sites.

      This Capsule provides information on the Subsurface
Volatilization and Ventilation System (SVVS)® process, an insitu
technology developed to increase oxygen flow to subsurface
materials, to facilitate microbial decomposition of organics while
volatilizing  and removing volatile organic contaminants. The
SVVS®  process was evaluated under  EPA's SITE program
during a 12-month period from April 1993 to April 1994 at the
Electro-Voice, Incorporated (EV) facility in Buchanan, Ml.  The
evaluation focused primarily on assessing the effectiveness of
the SVVS® process  for remediating the "dry well"  area  soils
contaminated with aromatic hydrocarbons,  and  halogenated
and  non-halogenated volatile, and  semivolatile organic com-
pounds.  Information  in this capsule emphasizes  specific site
characteristics and results  of the SITE field demonstration at
the EV facility. This capsule presents the following information:

      • Abstract
      • Technology description
      • Technology applicability
      • Technology limitations
      •  Process residuals
      • Site requirements
      •  Performance data
      • Technology status
      • Source of further information
Technology Description

      The SVVS® process utilizes soil vapor extraction in con-
junction with insitu bioremediation to clean soil,  sludge, and
groundwater. A typical SVVS® installation comprises a series of
air injection  and vacuum/extraction wells designed to circulate
air below ground to 1) increase the flow of oxygen in the soil to
enhance the rate  of organics destruction by indigenous soil
microbes and 2) volatilize and remove volatile organic contami-
nants from the soil. The configuration of the SVVS® is pre-
sented in Figure 1. A schematic cross-section of the system is
presented in Figure 2. This system consisted of three individu-
ally plumbed rows of  alternating vacuum  extraction  and air
injection wells referred to as reactor lines. Each reactor line is
plumbed to a single central vapor control unit (VCU)  used to
house air injection  and vacuum pumps and gauging, as well as
emissions control equipment.

      The injection wells are installed below the groundwater
table  and are  used to inject air into  the groundwater. The
developer claims that the air strips volatile contaminants from
the soil and water as it percolates through this saturated zone.
Extraction wells installed in the  vadose  zone pull the perco-
lated  air through the soil under vacuum,  further stripping con-
taminants. In addition, the increase in air  circulation in  the soil,
specifically oxygen, increases the rate of biodegradation by soil
microbes, according to the developer, and transforms contami-
nants into harmless end products such as carbon dioxide and
water. To aid in the circulation process, sand chimneys can be
installed. These are sand-packed borings which provide pas-
sive airflow between the subsurface layers, increasing both the
soil vapor extraction and the biodegradation  rates.

      If required by permits, off-gas extracted from the vacuum
extraction wells can be routed through a configuration of Bio-
logical Emissions  Control™ (BEC™) units  (a patent  pending
system which, according to  the developer, through biodegrada-
tion, achieves up to 80% reductions in concentrations of VOCs
in stack emissions  at approximately 20% of traditional emission
control costs). The off-gas  is then expelled to the atmosphere
through a vent pipe affixed to the extraction  pump. Vacuum
extraction emissions may also be favorably controlled within
regulatory limits by adjusting the air  injection  and  vacuum
extraction rates. However, if the levels of VOCs in the off-gas

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Figure 1.  SVVS® configuration at the Electro-Voice site.
                                                         air compressor  vacuum pump
Figure 2. Cross-sectional schematic of the Sl/VS®.

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are in  excess of acceptable levels, the off-gas exiting the
BEC™  units can be  routed through an activated carbon ad-
sorption unit as a final polishing step prior to discharge.

Technology applicability

      The SWS® process is applicable to sites contaminated
with gasoline,  diesel  fuels, and other hydrocarbons, including
halogenated compounds. The system is very effective  on ben-
zene, toluene, ethylbenzene,  and xylene (BTEX) contamina-
tion. The  process can also be  used to contain contaminant
plumes through its unique vacuum and air injection techniques.
The technology should be effective in treating soils contami-
nated  with virtually any  material that has  some volatility  or
biodegradability.  The technology can be applied to contami-
nated soil, sludge, free-phase hydrocarbon product, and ground-
water.  By changing  the injected gases, anaerobic  conditions
can be developed, and a microbial population can be used to
remove nitrate from groundwater. The aerobic SVVS® can also
be used to  treat heavy metals in groundwater by raising the
redox  potential of the groundwater and precipitating the heavy
metals.

       Over the past five years,  SVVS® has been employed at
over 130 sites where petroleum hydrocarbons have been re-
leased. The soil and groundwater  at several of  these  sites
have been  cleaned  to applicable regulatory standards within
and before the predicted remedial time frame. SVVS®  has also
been  implemented  to remediate halogenated aliphatic com-
pounds in the subsurface.

Technology Limitations

       In the application  of any insitu air sparging technology,
the potential exists for migration of contaminant vapors off site.
 It is imperative that the overall site remediation plan include a
 properly  engineered soil vapor  extraction (SVE)  system to
 capture the contaminated vapors emanating from the saturated
 zone.  Therefore, the application  of this technology is generally
 limited to sites where SVE is feasible. One possible exception
 to this is a  site  that  relies on a  remediation system  that
 maximizes the insitu biodegradation component of the technol-
 ogy to destroy less volatile contaminants in the saturated zone
 and vadose zone.

       The  effectiveness of SVVS® is sensitive to the lithology
 and stratigraphy of  the  saturated and  unsaturated zones.  In
 highly stratified soils, air may  travel far from the well along
 coarser strata before reaching the vadose zone, potentially
 bypassing the target contaminant areas. The lateral  migration
 of the air within the  saturated zone will generally be accompa-
 nied by a lateral spread in the  dissolved  contaminant plume.
 The overall remediation system design should incorporate mea-
 sures to control the  potential contaminant plume spread.

       In situations  in which dense non-aqueous phase liquids
 (DNAPLs)  are present,  it is possible to spread the immiscible
 phase and increase the size and concentrations of  the VOC
 plume. This may actually  be used as an advantage in  a site
 remediation through the mobilization of the residuals and, in
 conjunction with groundwater control, the realization of a more
 efficient mass removal process.

        SVVS®  may not  be  economically beneficial for
  remediation of materials of  a  very low permeability, such as
  stiff clay. Additionally, potential inorganic geochemical changes
  incurred through the application of the technology may  cause
  clogging of the aquifer.  The potential for fouling may be  evalu-
ated using available geochemical  models, and  avoided by
using a more appropriate gaseous medium.

Process Residuals

      The SVVS® process generates one major wastestream-
vapors from the vacuum  extraction  wells. Depending upon
regulatory requirements, the extracted air may be treated above
ground or released directly to the atmosphere.  In the early
stages of SVVS®  implementation,  the overall rate  of mass
transfer of contamination  to  the vapor phase may exceed
biodegradation rates. It is  during this  period, which lasts any-
where from two weeks  to a few months, that extracted vapors
may need to be treated above ground before release to the
atmosphere.  However, the magnitude of  treatment  will  de-
crease steadily over this period until biodegradation rates sur-
pass the  net rate of  transfer of contaminant mass  into the
circulating air. When this point is reached, the  vapor extraction
off-gas will consist  predominantly of carbon dioxide, which is
the major gaseous by-product resulting from  the biodegrada-
tion process. Consequently, the extent of  exsitu treatment is
reduced  significantly over that required by conventional SVE
systems, resulting in decreased capital and operations costs to
the implementer. To reduce these costs further and  promote
additional VOC destruction, the SVVS® design  employs the use
of proprietary biofilters  for treatment of the  extracted vapors.

      A minor process residual from the implementation of a
SVVS® system is soil generated during system-well installation
drilling activities. This soil can be containerized and disposed
in accordance with the appropriate regulatory  criteria.

 Site Requirements

       The SVVS® soil remediation system consists of several
 major mechanical components and requires the installation of
 injection/extraction  wells,  and,  possibly, sand chimneys. The
 system includes a positive displacement  blower or  air com-
 pressor, vacuum pump(s), emissions control equipment, and
 various monitoring  equipment.

       The  remediation area must be accessible to drill rigs
 and other heavy equipment  such as front-end loaders, back
 hoes, and/or trenching equipment. The site must also accom-
 modate the VCU used to house the SVVS® pumps and associ-
 ated equipment. System installation  time  depends upon the
 size of the plot and the depth to groundwater.
 Performance Data

       The SVVS®  process  was  evaluated  for its  ability to
 reduce volatile organic contaminants in the vadose zone soil of
 the "dry well" area at the Electro-Voice, Inc. site in Buchanan,
 Ml. The primary objective of the demonstration was to evaluate
 the developer's claim of a 30% reduction in the sum of seven
 specific volatile organic  compounds (i.e., benzene,  toluene,
 ethylbenzene, xylene, tetrachloroethene, trichloroethene,  and
  1,1-dichloroethene) in vadose zone soils of the treatment plot
 over  a 12-mo  period  of  operation. A  1-yr time frame  was
 chosen for testing purposes only, and the reduction claim does
  not reflect the limits of the technology. Under an actual reme-
  dial clean-up, the system  may require a longer time than was
  possible during the present study.

        Reductions in the  volatile  organics were proposed to
  occur through  the  combined effects of insitu biodegradation
  and soil vapor extraction.  These reductions were evaluated by

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 comparing the sum of the concentrations of the select volatile
 organic contaminants in the matrix prior to system startup and
 after 12 mo of system operation. Secondary objectives were
 established to  determine the relative  contributions  of  insitu
 biodegradation and vapor extraction to the removal and degra-
 dation of volatile organics from the subsurface.

       Soil samples  were  collected  from borings  within the
 physical boundaries  of the SVVS® system and sampled in a
 manner such that the entire vertical section of the vadose zone
 was represented. Five  distinct subsurface zones were identi-
 fied based on  lithology and  contaminant occurrence. These
 included the upper horizon (above the contaminant  source),
 sludge layer (predominant source of contamination), and  lower
 horizons A1, A2, and B (below the contaminant source).

       Since the  developer's claims were to reduce  seven
 volatile  organic contaminants  by  30%,  benzene,  toluene,
 ethylbenzene, and xylenes (BTEX), tetrachloroethene (PCE)i
 trichloroethene (TCE), and  1,1-dichloroethene (1,1-DCE) were
 considered the critical analytes for this demonstration. Analy-
 ses were also performed on  select  samples for the following
 non-critical parameters: total carbon (TC), total inorganic car-
 bon (TIC), nutrients (nitrate, phosphate), total metals plus mer-
 cury, cyanide, pH,  and  particle size distribution (PSD). An
 additional objective of this demonstration was to develop data
 on operating costs for the SVVS ® technology.

       The extracted vapor streams were analyzed by  continu-
 ous emission monitoring  (CEM) for O2,  CO2, and total hydro-
 carbons (THC).  Grab samples of the extracted vapor stream
 were collected for determining the concentration and  distribu-
 tion of individual volatile organic compounds.

       Shut-down tests were periodically performed  to assess
 the  presence and  magnitude of biological processes in the
 destruction of organic constituents in the subsurface. During a
 shut-down test, the injected  air stream is temporarily turned off
 resulting in the cessation of  oxygen delivery to the subsurface.
 If there is a robust aerobic microbial population in the  subsur-
 face, the available oxygen will be quickly  depleted. The shut-
 down test tracks the magnitude and rate  of oxygen  drop-off
 over a 24-hr period.

      At the Electro-Voice site,  the SVVS® process achieved
 an  overall 80.6%  reduction of the  sum of the seven critical
 VOCs over a 1-yr period from  vadose zone soils. This level of
 reduction greatly exceeded the developer's claim of  a  30%
 reduction over a 1-yr time frame. The average concentration of
 the sum of the seven analytes from the  hot zone  in the study
 area, prior to installation of the SVVS®, was 341.5 mg/kg. The
                             average concentration of the sum of the seven analytes after
                             one year of operation was 66.20 mg/kg.

                                   Reductions for each subsurface horizon are presented
                             in Table 2 and graphically depicted in Figure 3. The data reveal
                             that the most contaminated zone is the sludge layer, with an
                             average reduction of 81.5%. The other less contaminated hori-
                             zons exhibited reductions ranging from 97.8% to 99.8%.

                                   The reductions over the areal  extent  of the  site, as
                             determined from the individual boreholes, ranged from 71% to
                             over 99%. This  indicates  the  system operated relatively uni-
                             formly over the entire vadose  zone of the treatment plot, and
                             no significant untreated areas were encountered, regardless of
                             VOC concentration or lithology.

                                   The shut-down testing indicates that microbiological ac-
                             tivity was stimulated  at the site. Due to the  inherently  high
                             organic content of the soil, it was not clear how much of this
                             stimulation was due to contamination. The microbiological ac-
                             tivity, as determined from  the  first shut-down test,  was great-
                             est in portions of  the site where the VOCs were greatest, and
                             least active in areas of the site where the contamination was
                             small or absent. Seasonal variations as evidenced in the back-
                             ground wells, where  presumably  no contamination existed,
                             introduced uncertainty in data  interpretation. A comparison of
                             three shut-down  tests indicates  that biological activity  was
                             greatest during the beginning of remediation and progressively
                             decreased throughout the remainder of the demonstration, but
                             at a rate that was less than  the VOC mass removal  rates
                             attributed to vapor extraction alone. This would indicate that
                             biological processes play an increasingly important, but not a
                             dominant, role relative to vapor extraction as the remediation
                            proceeds.

                                  An analysis of  the volatiles from the vapor extraction
                            outlet is presented in Figure 4. The  graph  reveals that the
                            highest mass of volatiles was removed during the early phase
                            of the project. Furthermore, the mass of volatiles in the off-gas
                            stream gradually decreases to a low and constant level  after
                            approximately 230 days of operation.

                                  The SVVS® experienced no major operational problems
                            over the 12-mo study period. Once implemented,  the system
                            was easy to monitor and required minimal maintenance and/or
                            operator attention.

                                  The Biological  Emissions Control™  (BEC™)  unit, in-
                            stalled to biologically degrade VOCs from the off-gas stream,
                            was removed from the system after a few months of operation
                            and was not evaluated. Dispersive air modelling results showed
Table 2. S VVS® Performance Summary Zone 1 ("Hot Zone")
    Treatment Plot Horizons
        Upper Horizon
         Sludge Layer
       Lower Horizon A1
       Lower Horizon A2
       .Lower Horizon B
                                  Before
321.77
1661.03
 96.42
 37.68
 13.57
                    Critical VOCs*
                Concentration (mg/kg)
                                                                                   After
 0.74
307.69
 0.98
 0.42
 0.30
                                                                                                    % Reduction
99.77%
81.48%
98.99%
98.88%
97.79%
*Sum of Benzene, Toluene, Ethylbenzene, Xylene, 1,1-Dichloroethene, Trichloroethene, and Tetrachloroethene

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                           Non-Sludge Layers
                                                                         Sludge Layers
                                                             o 1000
                                                            o
                                                            o
                                                            o
                  Lower Horizon A1           Lower Horizon B
         Upper Horizon            Lower Horizon A2
                                                                 Sludge Layers
Figures.  Sl/l/S®performance.
            03
140


120


100


 80


 60


 40


 20


   0
                    0
              50
100
                                                  150       200      250

                                                    Elapsed Time (days)

Figure 4.  Total Mass Flow Rate of Critical VOCs Versus Time.
300
350
                                                                                                      400
that  contaminant concentrations were below  established air
quality standards and discharge criteria for the site were met
without any additional treatment.

      The SVVS® was installed at the site based on contami-
nant distribution information derived from remedial investigation
data. During the baseline sampling event under the SITE Dem-
onstration, it became evident that a portion of the system was
installed within a clean area of the site. Operation of the system
was easily adjusted while maintaining the existing hardware to
concentrate remedial action in more contaminated areas. How-
ever, installation of the  system in the non-contaminated area
impacted costs since materials  and  labor were expended. The
                                              excess installation did not in any way impact the performance
                                              of the system. This situation stresses the importance of accu-
                                              rately defining the extent and magnitude of contamination prior
                                              to the implementation of insitu  technologies. Insitu  technolo-
                                              gies  may require site characterization in greater detail than is
                                              commonly available from remedial investigations.

                                                    The cost to remediate 21,300 yd3 of vadose zone soils
                                              during a full-scale cleanup  over a 3-yr period at the Electro-
                                              Voice Superfund site in Buchanan, Ml was estimated to be
                                              $192,237 or $9/yd3,  not including effluent treatment and dis-
                                              posal. The majority  of  this was incurred in  the first  year,
                                              primarily due  to well drilling and associated site preparation. If

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