xvEPA
United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102G)
EPA 542-R-98-009
October 1998
http://vwvw.epa.gov/swertio1
http://clu-in.org
Field Applications of In Situ
Remediation Technologies:
Ground-Water Circulation
Wells
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EPA-542-R-98-009
October 1998
Field Applications of In Situ Remediation Technologies:
Ground-Water Circulation Wells
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Technology Innovation Office
Washington, DC 20460
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Notice
This status report was prepared by: Environmental Management Support, Inc., 8601 Georgia Avenue,
Suite 500, Silver Spring, MD 20910 under contract 68-W6-0014, work assignment 065 with the U.S.
Environmental Protection Agency. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use. For more information about this project contact: Kathleen
Yager, U.S. Environmental Protection Agency, Technology Innovation Office,2890 Woodbridge
Avenue, Building 18 (MS101), Edison, New Jersey 08837 (732-906-6912), e-mail: yager.kathleen@
epa.gov.
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Foreword
Approximately 85% of the hazardous waste sites in the United States have contaminated ground
water. The conventional approach for remediating contaminated ground water has been to extract
the contaminated water, treat it above ground, and reinject or discharge the clean water ("pump-
and-treat"). The recovered contaminants must be disposed of separately. It is becoming
increasingly apparent that pump-and-treat technologies require considerable investment over
extended period of time, and often times do not actually clean up the source of the contamina-
tion. Current policies and law stress "permanent" remedies over containment. Consequently,
there is considerable interest and effort being expended on alternative, innovative treatment
technologies for contaminated ground water.
This report is one in a series that document recent pilot demonstrations and full-scale
applications that either treat soil and ground water in place or increase the solubility and mobility
of contaminants to improve their removal by other remediation technologies. It is hoped that this
information will allow more regular consideration of new, less costly, and more effective
technologies to address the problems associated with hazardous waste sites and petroleum
contamination. This and the other reports listed below are available to the public from the
Technology Innovation Office website: http://clu-in.org/pubitech.htm.
Surfactant Enhancements
Treatment Walls
Hydrofracturing/Pneumatic Fracturing
Cosolvents
Electrokinetics
Thermal Enhancements
In Situ Chemical Oxidation
Ground-Water Circulation Wells
in
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IV
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Contents
Introduction 1
Purpose and Process 1
Technology Needs 1
Technology Description 2
Department of Defense Sites 4
Edwards Air Force Base 4
Keesler Air Force Base 6
March Air Force Base 8
Massachusetts Military Reservation 9
Port Hueneme Naval Exchange Site 12
Tyndall Air Force Base 14
Department of Energy Sites 16
Portsmouth Gaseous Diffusion Plant 16
Westinghouse Savannah River Site 18
EPA Superfund Sites 20
Cabot/Kopper's Superfund Site 20
Sweden-3 Chapman Superfund Site 21
Private/Commercial Sites 24
Amcor Precast 24
Former Service Station 25
Top Stop Store 27
Dry Cleaning Facilities 28
Wood Treatment Site 30
General References 31
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VI
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Introduction
Purpose and Process
The purpose of this document is to describe completed and ongoing pilot demonstrations and
full-scale applications of ground-water circulation well systems for the remediation of saturated
soils and ground water at hazardous waste sites.
Information for this report came from computerized databases such as the Dialog Information
Services and the Environmental Protection Agency's (EPA) Vendor Information System for
Innovative Treatment Technologies (VISITT). Additional materials were obtained from EPA
Regional Offices, the Ground Water Research Technology Analysis Center (GWRTAC),
Department of Energy staff at the Oak Ridge National Laboratory and Westinghouse Savannah
River, Department of Defense site staff, and Battelle. Personal interviews and discussions with
representatives of EPA and other federal agencies, state environmental quality offices, academic
research centers, hazardous waste remediation consulting firms, and technology vendors
provided supplementary information.
The sites selected for this report represent a mix of government and private demonstrations of
various applications of ground-water circulation well systems. The level of detail may vary by
demonstration depending upon the availability of information and the willingness or ability of the
site representative to share proprietary data.
Technology Needs
Although ground-water contamination reportedly has been found at up to 85% of hazardous
waste sites, few efficient and cost-effective cleanup solutions have been identified. The number
of solutions available has been limited by the complexity of existing ground-water technologies,
the diversity of site characteristics, and the high cost of operation and maintenance for
remediation. Two classes of contaminants commonly present at many of these sites are
chlorinated volatile organic compounds (VOCs) and petroleum products and their constituents.
Ground-water circulation wells (GCWs) are a developing technology designed to remove
contaminants from ground water and saturated soils. They are applied to chlorinated solvents,
hydrocarbons, and any strippable contaminant. The technology is simpler than other often-used
technologies such as air sparging or pump and treat. It is designed to run continuously with only
routine maintenance, and usually has no moving parts below ground and no complicated
components. Most of the field applications of this technology have involved treating halogenated
VOCs, such as trichloroethene (TCE), and petroleum products and their constituents such as
benzene, toluene, ethylbenzene, and xylene (BTEX). Applications of GCWs to non-halogenated
VOCs, semi-VOCs (SVOCs), pesticides, and inorganics have been proposed based on
modifications of the basic remedial process. The technology also has been applied to ground
water contaminated with both radionuclides and VOCs. It has been applied to a wide range of
soil types from silty clay to sandy gravel.
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The process can remove VOCs continuously from ground water without pumping water to the
surface, avoiding the need to handle contaminated water above ground or to dispose of or store
partially treated water. The technology does not require injection wells, discharge lines, discharge
fees, permits, or water rights to recirculate and discharge ground water. The contaminated vapors
generated in the process are more easily removed and treated above ground than contaminated
water.
Ground-water circulation wells can be used in conjunction with other technologies such as
bioremediation, bioventing, soil vapor extraction, surfactant, zero-valent dehalogenation, and
oxidation.
Engineering decisions regarding the application of GCWs must take into account that this
technology is site specific. If the system is not properly designed or constructed, the contaminant
plume may spread beyond the radius of influence or the wells may become clogged. GCWs may
have limited effectiveness in shallow aquifers because of the limited space for circulation.
Addition of air can cause sealing in wells.
Technology Description
GCW systems create a circulation pattern in the aquifer by drawing water into and pumping it
through the well, and then reintroducing the water into the aquifer without bringing it above
ground. Depending upon the configuration of the system, the technology is also known as in-well
vapor stripping, in-well air stripping, in situ vapor stripping, in situ air stripping, and vacuum
vapor extraction.
The well is double-cased with hydraulically separated upper and lower screened intervals within
the aquifer. The application may be enhanced by the addition of ozone, activated carbon
adsorption, or biological treatments. The radius of influence of the well can also be modified
through the additions of chemicals to allow in situ stabilization of dissolved metals in ground
water. In general, the selection of a configuration is dependent upon site conditions,
contaminants, and the vendor.
The system can be configured with an upward in-well flow or a downward in-well flow. The
most common configurations involve the injection of air into the inner casing, decreasing the
density of the ground water and allowing it to rise. This constitutes a type of air-lift pumping
system. Through this system, volatile contaminants in the ground water are transferred from the
dissolved phase to the vapor phase by the rising air bubbles. Contaminated vapors can be drawn
off and treated above ground or discharged into the vadose zone, through the upper screened
interval, to be degraded via in situ bioremediation.
The ground water, which has been partially stripped of volatile contaminants, moves upward
within the inner casing and is eventually discharged into the outer casing, moving through the
upper screened interval into the vadose zone. Once returned to the subsurface, the ground water
flows down reaching the lower portion of the aquifer where it is cycled back into the lower
screened interval, replacing the water that rose due to the density gradient. This cycling of water
in the area around the well creates a hydraulic circulation pattern that allows continuous cycling
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of ground water in situ through the air stripping process. Ground water is repeatedly circulated
through the system until sufficient contaminant removal has taken place.
Examples of the systems developed based on this technology are NoVOCs™, Unterddruck-
Verdampfer-Brunnen (UVB™) or "vacuum vaporized well," Density Driven Convection (DDC),
and C-Sparge™.
NoVOCs™ is similar to the generic system described above. It uses a compressor to deliver the
air to the contaminated water column. The bubble-water mixture rises in the well until it
encounters a deflection plate. At this point the air bubbles combine. The water flows out of the
well through the upper screen and the coalesced bubbles are drawn off by vacuum for above
ground treatments of VOCs.
The UVB™ system supplements air-lift pumping with a submersible pump to maintain flow at a
standard rate. It also employs a stripper reactor to facilitate transfer of volatile compounds from
aqueous to gas phase before the water is returned to the aquifer.
The DDC system emphasizes the enhancement of bioremediation and involves the discharge of
extracted vapors into the vadose zone for degradation by naturally occurring microorganisms.
Oxygen is supplied to both the saturated zone and the vadose zone to promote natural aerobic
processes.
The C-Sparge™ system combines in situ air-stripping, where the dissolved chlorinated solvents
are extracted from the aqueous solution into small bubbles, and the introduction of encapsulated
ozone to oxidize the contaminants.
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Department of Defense Sites
Installation Date:
1995
Contaminants:
TCE
Enhancement:
Not applicable
Soil Type:
Sand, gravel
Points of Contact:
Tyler J. Gilmore
Battelle Pacific Northwest
Laboratory
Richland, WA 99352
Tel: 509-376-2370
Fax: 509-376-5368
E-mail: tyler.gilmore@pnl.gov
David Steckel
AFFTC/EMR
5 East Popson Ave, Bldg 265 OA
Edwards AFB, CA 93524-1130
Tel: 805-277-1474
Fax: 805-277-6145
E-mail:
steckeld%em(3>mhs. elan.af.mil
Edwards Air Force Base, CA
A field demonstration of in-well vapor stripping (NoVOCs™)
for remediation of trichloroethene (TCE) in ground water was
conducted at Edwards Air Force Base, California, from 1995-
1996. This was the first demonstration of a system of this kind
in the U.S. It was conducted as an interim cleanup action as
part of the Comprehensive Environmental Response,
Compensation, and Liability Act (Superfund) process.
Site Background
The primary use of Edwards AFB is for aircraft research,
development, and testing programs. The ground water beneath
the site is contaminated with dissolved volatile organics,
primarily TCE. The site consists of unconsolidated sediments
overlying granite bedrock. The sediments are alluvial and
lacustrine deposits of sand with some gravel and smaller
fractions of caliche, silt, and clay. Ground water occurs at 25 ft
below ground surface (bgs). The vertical hydraulic conductivity
of the aquifer is Ift/d with a vertical gradient of 0.1. The
horizontal conductivity is lOft/d with a gradient of 0.005.
Previous investigations identified the maximum concentration
of TCE in the area to be 502 |ig/L; the average concentration
was 300 ng/L. Maximum concentrations upgradient of the
demonstration site were as high as 3,400 |ig/L.
Technology Application
Measurements specifically important to the in-well vapor
stripping system, such as hydraulic conductivity and soil
chemistry, were obtained prior to application. The monitoring
network consisted of a treatment well with associated access
tubes, five monitoring wells, three piezometers, three flow
sensors, two characterization wells, and two older monitoring
wells drilled during the remedial investigation. The treatment
well was completed to 50 ft bgs with the lower screen from 40
to 50 ft, and the upper screen from 3 to 18 ft bgs. A treatment
trailer equipped with an air compressor, blowers, generator,
instrumentation to control the system, diesel fuel tank, and
high-efficiency particulate-air filter was placed on site. Air was
injected into the base of the well by the compressor. This
created a bubble column that lifted the water and stripped the
contaminants, which were vacuumed off and sucked through a
carbon granular activated cannister. The compressor was
eventually replaced with blowers. The demonstration was
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operated nearly continuously for 191 days. Pumping rates of
water pushed through the well via lifting (7-10 gpm) and air-
injection rates (34-62 standard cubic feet per minute) were
reconfigured during the process.
Results
Geological heterogeneity at the site resulted in an asymmetrical
cleanup zone. The zone of influence defined by the TCE
reduction had at least a 50-ft radius in the upper zone of the
aquifer and at least a 10-ft radius and possibly greater that a 30-
ft radius in the lower zone. The concentration in the upper zone
decreased from highs of 34-160 |ig/L to below the regulatory
limit of 5 |ig/L. In the lower zone of the aquifer (between 45-50
ft below ground), the concentrations in the well nearest the
treatment well fell from 270 to 173 |ig/L. A low permeability
layer at about 44 ft below ground appeared to limit the
recirculation of the water. The stripping ratio of the system
averaged 90%; that is, 90% of the contaminant was removed
per pass through the system.
This system was moved to an area of higher concentration at
the site and has been operational since December 1997. The
facility is in the process of adding another stripping well to the
system.
The funding for this field demonstration was provided by the
Air Force and the Department of Energy (DOE). The Air
Force's total expenditures for installing the wells, assembling
the equipment, and operations and maintenance, were
approximately $600K. DOE provided additional personnel,
equipment, a trailer, and software for a total of approximately
$217K.
Site-specific References
Gilmore, T.J.; White, M.D.; and Spane, F.A. Performance
Assessment of the In-Well Vapor-Stripping System, Pacific
Northwest National Laboratory, Richland, Washington,
October 1996
Gilmore, T.J.; Spane, F.A.; White, M.D.; Lewis, R.E.; and Gee,
G. W. "The Effect of Geologic Heterogeneities on the Installa-
tion and Operation of the Pilot In-Well Vapor Stripping System
at an Air Force Base in California," 28th Annual Meeting of
the Geological Society of America, Denver, Colorado, October
28-31, 1996
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White, M.D., and Gilmore, TJ. Numerical Analysis of the In-
Well Vapor-Stripping System Demonstration at Edwards Air
Force Base, Pacific Northwest National Laboratory, Richland,
Washington, 1996
Installation Date:
1995
Keesler Air Force Base, MS
A field demonstration of a Density Driven Convection (DDC)
system coupled with soil vapor extraction (SVE) was
conducted at Keesler Air Force Base (AFB) in Biloxi,
Mississippi from 1995-1997. The primary contaminants of
concern at the site included total petroleum hydrocarbons
(TPH) and benzene, toluene, ethylbenzene, and xylene (BTEX)
in ground water.
Site Background
Kessler AFB is located approximately 80 miles east of New
Orleans, Louisiana. The upper 3-4 ft of soil is silty sand with
fine- to medium-grained sand to 22 ft below ground surface
(bgs) and clay beneath. The demonstration was conducted in a
shallow, unconfmed aquifer with ground water at approxi-
mately 7-8 ft bgs. The horizontal and vertical conductivities
were measured at 32 and 9.5 ft/d, respectively. The source of
contamination was gasoline and diesel fuel leaks from
underground storage tanks (USTs) and dispensers. TPH
concentrations up to 21,000 mg/kg in soil were detected at 7 ft
bgs, and 9,900 mg/kg at 9 ft bgs. Concentrations tapered off
below 9 ft. The ground-water plume extended approximately
400 ft down gradient of the site. The maximum concentrations
of TPH and BTEX within the treatment area were 96 and 7.46
mg/L, respectively. The maximum TPH and BTEX ground-
water concentrations detected downgradient, outside the
treatment area were 32 and 14 mg/L, respectively.
Technology Application
This project began with a pilot application followed by a full-
scale installation. The pilot system included one DDC well and
one SVE well. The large-scale system consisted of 32 DDC
wells and 6 SVE wells. The DDC wells had screened intervals
from 4-14 ft and 16.5-21.5 ft bgs. The SVE wells were
installed to 7 ft and screened 2-7 ft bgs. The SVE wells were
installed to prevent vapor migration and to draw oxygen from
the DDC wells into the vadose zone. The system is designed to
strip volatile compounds from ground water flowing through
the well. As the stripped hydrocarbons and oxygen are
introduced via the upper screen into the surrounding soils they
Contaminants:
TPH, BTEX
Enhancement:
Not applicable
Soil Type:
Silty sand, sand, clay
Point of Contact:
James R. Gonzales
Technology Transfer Division
AFCEE/ERT
3207 North Road - Bldg 532
Brooks Air Force Base
TX 78235
Tel: 210-536-4324
Fax: 210-536-4330
E-mail: james.gonzales@
hqafcee.brooks.af.mil
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are subject to removal by the SVE system. The oxygenated
ground water and air flowing out of and away from the DDC
well also enhance bioremediation in soils and ground water.
Results
The system operated for approximately 18 months. The
estimated mass of TPH removed from the SVE effluent was
approximately 3,449 Ibs, primarily by direct volatilization.
Average TPH concentrations in the monitoring wells decreased
by 87% from 51.4 mg/L to 6.5 mg/L, while the average BTEX
concentrations decreased by 91% from 4.8 mg/L to 0.42 mg/L.
However, over the same period, concentrations in down-
gradient wells outside the treatment area increased to levels
more than double the original amount and finally levelled off to
concentrations slightly higher than in samples collected before
system startup. This could have been the result of incomplete
ground water capture by the large-scale system following
desorption of soil contaminants by the DDC well effluent.
TPH and BTEX soil concentrations dropped throughout the site
during the demonstration, averaging a 98% decrease in the
capillary fringe. Concentrations for both contaminant groups
dropped anywhere from 35 to 87% at various depths below the
water table.
Since new influent and effluent monitoring points were not
installed between the pilot and large-scale system, various
assumptions were required to estimate mass removal rates.
Therefore, it is unclear as to what proportion of the total mass
removed is attributable to the SVE rather than the DDC system,
as well as how much of the contaminants actually migrated off-
site.
The total cost of this field demonstration was approximately
$360K, $100K of which was for the pilot study.
Site-specific References
Wasatch Environmental, Inc. DDC In-Well Aeration Tech-
nology Demonstration, Keesler Air Force Base, AOC A (ST-
06), BXService Station, U.S.EPA ID. #MS2 570 024 164,
Biloxi Mississippi, prepared for the Air Force Center for
Environmental Excellence, Brooks Air Force Base, Texas, July
1998
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March Air Force Base, Riverside, CA
Installation Date:
1993
A field demonstration of a UVB™ ground-water recirculating
well for remediation of trichloroethene (TCE) was conducted at
March Air Force Base, California between 1993-1994.
Contaminants:
TCE
Enhancement:
Not applicable
Soil Type:
Fine-grained sand & silt
Point of Contact:
Michelle Simon
U.S. EPA
Risk Reduction Engineering
Laboratory
26 West Martin Luther King
Drive
Cincinnati, OH 45268
Tel: 513-569-7469
Fax:513-569-7676
E-mail: simon.michelle
@epa.gov
Site Background
The site is a solvent disposal site. The underlying formation is a
fine-grained sand and silt sediment. The depth to ground water
is approximately 40 ft below ground surface (bgs) and the
thickness of the aquifer is approximately 80 ft. The hydraulic
conductivity of the aquifer was 10"4 cm/s, and the gradient was
0.007. Initial sampling indicated TCE concentrations ranging
from 3.4 to 1,000 |ig/L with an average of 500 |ig/L.
Technology Application
Prior to installing the UVB™ well, a pilot boring was installed
to a depth of 118.5 ft bgs to characterize stratigraphy. The
UVB™ treatment well was drilled to a depth of 87.5 ft. Three
monitoring wells were installed within the UVB™ borehole,
one screened across the influent section and two at 90°
screened across the effluent section. The distance between the
effluent and influent screens was 40 ft. Two clusters of
monitoring wells were located 40 and 80 ft downgradient of the
UVB™ well. The clusters consisted of discretely-screened
shallow, intermediate, and deep wells. A vadose zone well was
installed 60 ft from the UVB™ well. The blower was located
adjacent to the well-head and connected to two vapor phase
carbon canisters. The 18-month operational monitoring
consisted of effluent air monitoring and sampling, ground-
water sampling, and analysis.
Results
EPA' Superfund Innovative Technology Evaluation Program
reports that, over the 18 months of operation, TCE concen-
trations averaged 250 |ig/L, varying from 47 to 270 |ig/L.
Influent TCE concentrations in the lower screen varied between
non-detectable and 320 jig/L throughout the study, averaging
30 |ig/L. Occasional influent values that were greater than 30
|ig/L indicated mechanical problems with the system. Effluent
concentrations varied between non-detectable and 15 |ig/L. The
stripper unit indicated that TCE removal was greater than 90%
for 95% of the samples, and 95% removal was achieved for
77% of the samples.
The capital cost for one UVB™ well was approximately
$180K. First year operations and maintenance (O&M) costs
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were approximately $75K, and second year O&M costs were
approximately $42K. The cost for ground-water treatment was
about $260 per 1,000 gallons of treated water. The UVB™ well
was designed to treat about 1M gallons per year.
Approximately 60-90% of the ground water treated was
recirculated.
Site-specific References
Bannon, Jeffrey L.; Sontag, J.G.; Sabol, J.R.; andDominick,
M.T. In-Situ Groundwater Remediation: Pilot Study of the
UVB-Vacuum Vaporizer Well, March Air Force Base,
California, presented at the 88th Annual Meeting and
Conference of the Air and Waste Management Association,
San Antonio, Texas, June 18-23, 1995
EPA SITE Technology Capsule, "Unterdruck-Verdampfer-
Brunnen Technology (UVB) Vacuum Vaporizing Well,"
EPA/540/R-95/500a, July 1995
Massachusetts Military Reservation, Cape Cod, MA
A field demonstration of two ground-water recirculating well
configurations (NoVOCs™ and UVB™) was conducted at the
CS-10 plume at Massachusetts Military Reservation (MMR),
Cape Cod, Massachusetts, in 1996. The primary contaminant
addressed in this demonstration was trichloroethene (TCE).
Installation Date:
1996
Contaminants:
TCE, other solvents
Enhancement:
Carbon
Soil Type:
Fine- to coarse-grained sand
Points of Contact:
James R. Gonzales
Technology Transfer Division
AFCEE/ERT
3207 North Road - Bldg 532
Brooks Air Force Base
Site Background
MMR is located in the upper western portion of Cape Cod.
The subsurface soils are primarily sand and silt. Lakes, ponds,
and rivers formed during the last glacial retreat and active and
abandoned cranberry bogs are the major surface water features
of the area. The depth to ground water at the test site ranges
from 15 to 45 feet below ground surface (bgs), depending on
surface topography. The aquifer is approximately 230 ft thick.
The estimated horizontal conductivity was 144 to 230 ft/d, and
the hydraulic gradient was 0.002. The primary contaminant is
TCE, which probably originates from maintenance of ground-
to-air missiles and armored and wheeled vehicles. Pre-pilot test
data indicated maximum TCE concentrations of 2,800 |ig/L in
ground water, with lower concentrations of other chlorinated
solvents, hydrocarbons, and metals.
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TX 78235
Tel: 210-536-4324
Fax: 210-536-4330
E-mail:
james.gonzales@hqafcee.
brooks.af.mil
Spence Smith
322 East Inner Road
OTIS ANGB, MA 02542-5028
Tel: 508-968-4670 ext.5603
Fax: 508-968-4673
E-mail: spence.smith@mmr.
brooks.af.mil
Technology Application
The UVB™ system installed at CS-10 North consisted of two
triple-screen treatment wells installed to a depth of 275 ft. Each
well is designed to induce two vertically adjacent circulation
cells intended to capture the full 120-ft thickness of the plume.
At each well, reinjection screens are located in the upper and
lower sections of the plume, and an extraction screen is located
in the middle portion of the plume. Ground-water extraction
and reinjection for the UVB™ system is accomplished using
submersible pumps. Air stripping of volatile organic chemicals
(VOCs) occurs under negative pressure using a patented
stripper in a below-ground vault. Offgas is filtered with
granular activated carbon (GAC) prior to release. Thirty-three
monitoring wells located at upgradient, cross-gradient,
downgradient, and near-field locations and three piezometers
were used to monitor circulation cell development at the
UVB™ test area.
The No VOCs™ system installed at CS-10 South included two
dual-screen/dual-casing wells that each induced a single
circulation cell. The wells were installed to a depth of 245 ft.
The extraction screens were located at the base of the plume
and the reinjection screens were located in the upper portion of
the 100-ft thick plume. The wells utilized air-lift to facilitate
pumping. VOCs were stripped via in-well sparging using
closed-loop positive-pressure regenerative blowers. VOC-laden
air was circulated through GAC and then redirected to the
wells. Thirty-two monitoring wells located at upgradient, cross-
gradient, downgradient, and near-field locations and three
piezometers were used to monitor circulation cell development
at the No VOCs™ test area. Ground-water monitoring was
conducted on a monthly basis during the 5-month pilot test.
Subsequently, quarterly monitoring of a smaller number of
wells at each site has been performed. The project began with a
third location (UVB™), which was closed after the 5-month
pilot since concentrations were determined to be too low to
evaluate the effectiveness of the technology.
Results
The systems were originally run as part of a 5-month pilot-scale
evaluation. Results from the UVB™ system indicated effluent
concentrations did not reach the target of 1 ng/L. TCE
concentrations in ground water near the upper effluent screen
remained relatively constant at approximately 100 |ig/L.
Middle zone or influent TCE concentrations dropped from
approximately 600 to 180 |ig/L. However, upgradient
concentrations, outside the zone of influence of the wells, also
10
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dropped from approximately 400 to 150 |ig/L during the same
period. Lower zone TCE concentrations corresponding to the
lower effluent screen remained nearly constant throughout the
period at 200 |ig/L. Results from the NoVOCs™ system also
indicated effluent concentrations did not reach the target of 1
Hg/L. TCE in the reinjection zone was reduced from 2,700
|ig/L to approximately 100 |ig/L, while concentrations in the
extraction zone remained stable at approximately 1,300 |ig/L.
TCE in the monitoring wells was reduced by 42-97%, whereas
concentrations in the lower zone increased by 241%. Other
solvents' concentrations were reduced below detection levels.
Subsequent to the pilot phase of operation, the Air Force
Center for Environmental Excellence (AFCEE) has continued
operation of both systems as an interim action for mass
removal. Over an 18-month period, based on calculations from
offgas samples, approximately 40 kg of VOCs have been
removed by the 120-gpm UVB™ system, and 84 kg of VOCs
have been removed by the 300 -gpm NoVOCs™ system.
Effluent concentrations for the UVB™ system have generally
been below the maximum contaminant level (MCL) of 5 |ig/L
for TCE. Effluent concentrations for the NoVOCs™ system
have generally been in excess of the MCL since initiation of the
pilot test. However, background levels for TCE are higher at
the NoVOCs™ site (approximately 1,000 |ig/L) than at the
UVB™ site (about 550 |ig/L). Average stripping efficiency was
95.5% for the UVB™ system and 91% for the NoVOCs™
system.
The cost of the CS-10 demonstration was approximately
$3.6M. This included approximately $2.1M for drilling and
construction, $616K for sampling and analysis, $442K for
project management, $33 IK for design and pre-construction
planning, and $96K for system evaluation reports. The total
cost for the project, including the terminated third location, was
approximately $5.3M.
Site-specific References
Parsons Engineering Science, Inc., Evaluation ofGroundwater
Circulation Well Technology at the Massachusetts Military
Reservation (MMR) on Cape Cod, Massachusetts, prepared for
the Air Force Center for Environmental Excellence, Brooks Air
Force Base, Texas, June 1997
Conde, P. and Wasp, R.G. "In Situ Remediation of Plume
Using Vertical Recirculation Technology," Battelle, First
11
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International Conference on Remediation of Chlorinated and
Recalcitrant Compounds, Monterey, California, May 1998
Dwight, D. M.; Mantovani, P.P.; and English, J. "Pilot
Recirculating Well System (NoVOCs™) for Remediation of a
Deep TCE Plume," Battelle, First International Conference on
Remediation of Chlorinated and Recalcitrant Compounds,
Monterey, California, May 1998
Lakhwala, F.; Desrosiers, R.; and Wasp, R.G. "A Unique
Groundwater Circulation Well Technology: Case Study MMR
CS-10 Plume," Battelle, First International Conference on
Remediation of Chlorinated and Recalcitrant Compounds,
Monterey, California, May 1998
Ward, D.; Bostick, K.; and Carman, J. "Effects of Anisotropy
and Low Conductivity on Recirculating-Well Performance,"
Battelle, First International Conference on Remediation of
Chlorinated and Recalcitrant Compounds, Monterey,
California, May 1998
Port Hueneme Naval Exchange Site, CA
Installation Date: A field demonstration of ground-water circulating wells
1995 (GCW) for remediation of benzene, toluene, ethylbenzene and
xylene (BTEX) in ground water was conducted at Port
Hueneme Naval Exchange site, California in 1995. These wells
Contaminants: ar£ variations of the UVB™ technology.
D IJiX
Site Background
The site is a former gasoline station which was contaminated
Enhancement: with approximately 11,000 gallons of gasoline that leaked from
Not applicable two delivery lines. The shallow soils consist of three layers:
fine-grained silty sand to 5.6 ft below ground surface (bgs),
fine- to coarse-grained sand to 20.3 ft bgs, and sandy-to-silty
clay between 20.3-26.2 ft bgs. The contamination is confined to
Soil Type: ^e Upper perched aquifer. The depth to ground water is
Silly sand, sand between 3.3-12.1 ft bgs. The horizontal hydraulic conductivity
was measured at 3.84xlO"2 cm/s, and the vertical hydraulic
conductivity at 3.84xlO"3 cm/s. Pre-treatment concentrations of
BTEX ranged from 4.66 mg/L at the well near the source to
118 mg/L at the deep monitoring wells. The concentrations
were lower near the source because well placement was based
upon incorrect characterizations provided in a previous project.
12
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Point of Contact:
Barry Spargo
Code6115NRL
Washington, DC 20375
Tel: 202-404-6392
Fax:202-404-8515
E-mail:
bspargo@ccf.nrl.navy.mil
Technology Application
The system consisted of four circulating wells. One (GCW-
400) was installed near the source and three (GCW-200) were
installed downgradient of the main spill to provide plume
containment. The upper and lower screens of the GCW-400
extended from 7.9-15.7 ftbgs and 21.8-26.3 ftbgs,
respectively. The well was equipped with a single blower and
submersible pump. Four clusters of three monitoring wells
were installed at various depths around the well. The three
GCW-200 wells were installed with overlapping radii of
influence to form a "biocurtain" to prevent off-site migration of
contaminants. This biocurtain was possible since
bioremediation was added secondarily to the site. The upper
and lower screens of these wells were placed between 7.2-16.4
ft bgs and 23-28.5 ft bgs, respectively. A total of eight
monitoring wells were placed around the "biocurtain." An
intensive monitoring schedule was followed including eight
quarterly sampling events.
Results
The demonstration began in January 1995 and lasted for 18
months. After six months of operation, data from the wells in
the biocurtain indicate BTEX concentrations dropped from 77
mg/L to 2 |ig/L. BTEX concentrations in the ground water from
the deep wells were reduced from 118 mg/L to under 1 |ig/L.
Within 8 months of operation, BTEX in the shallow monitoring
wells closest to the GCW-400 were reduced by 52% from 4.66
to 2.88 mg/L.
The cost of this field demonstration, including capital and
operations and maintenance costs, was approximately $184K.
This does not include the research and development costs of
the project.
Site-specific References
Spargo, B. J. (ed.) In Situ Bioremediation and Efficacy
Monitoring, Naval Research Laboratory, Washington, DC
Report No. NRL/PU/6115-96-317, 1996
Installation Date:
1994
Tyndall Air Force Base, FL
A field demonstration of a modified coaxial ground-water
circulating (mKGB) system coupled with a modified bio-
venting well (MBW) system for remediation of hydrocarbons
in both the saturated and unsaturated zones was performed in a
13
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Contaminants:
TPH
portion of a large plume at Tyndall Air Force Base, Florida,
from 1994-95.
Enhancement:
Bioventing
Soil Type:
Sand
Point of Contact:
Bruce C. Alleman
Battelle
505 King Avenue
Columbus, OH 43201
Tel: 614-424-5715
Fax: 614-424-3667
E-mail: allemanb@battelle.org
Site Background
The site, once a tank farm, was contaminated primarily with jet
fuel as a result of leaking underground storage tanks. The soil
is sandy with ground water at 5 ft below ground surface (bgs).
Attempts were made to determine the water flow rate but
results were highly variable.The maximum concentration of
total petroleum hydrocarbons (TPH) in ground-water samples
collected prior to the demonstration was approximately 16
mg/L.
Technology Application
The MBW system consisted of a simple air lift pump installed
in a 4-in diameter bioventing well modified to extend into the
ground water with one screened section from 11 to 15 ft bgs
and the other from 2 to 6 ft bgs. The mKGB system was
installed in an 8-in diameter well casing and screened the same
as the MBW. The monitoring system included five piezometers
with screens placed at the middle of the upper screen of each
ground-water circulating well (GCW), one piezometer with the
screen placed at the middle of the lower screen of each GCW,
and eight tri-level ground-water monitoring points placed at
varying distances from the wells with probes at 9, 12, and 15 ft
bgs. The MBW system was operated for 3 months and the
mKGB system for 9 months. Each system was operated at an
airflow rate of 1 standard cubic foot per minute, the maximum
rate that did not result in the excessive discharge of
contaminant vapor from the ground surface. Hydrocarbon
concentrations were measured in influent, effluent, and offgas
samples.
Results
The demonstration lasted for 12 months, from July 1994 to July
1995. After one year of operation the concentration of TPH
ranged from non-detectable to a high of approximately 15
mg/L.The conclusion from this demonstration was that these
two technologies could be effectively coupled to treat
hydrocarbon contamination. However, questions remain about
the efficiency of this type of application.
The total cost for this small-scale demonstration was
approximately $80K.
14
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Site-specific References
Alleman, Bruce C. Final Report on In-Well Air
Stripping/Bioventing Study at Tyndall Air Force Base, Florida,
Report No. AL/EQ-TR-1995-0039, Battelle, Columbus Ohio,
1995
15
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Department of Energy Sites
Installation Date:
1996
Contaminants:
TCE, TC"
Portsmouth Gaseous Diffusion Plant, Piketon, OH
A field-scale demonstration of horizontal recirculation wells
coupled with treatment modules for remediation of trichloro-
ethene (TCE) and technetium-99 (Tc99) was conducted at the
X-701B site of the Portsmouth Gaseous Diffusion Plant in
Piketon, Ohio, in 1996. This demonstration followed an earlier
pilot test of a horizontal well system at an uncontaminated site
at Portsmouth.
Enhancements:
Fe°, Activated Carbon
Soil Type:
Sand, gravel
Point of Contact:
Nic Korte
Oak Ridge National Laboratory
Grand Junction, CO 81503
Tel: 970-248-6210
Fax: 970-248-6147
E-mail: nek@ornl.gov
Site Background
The site is contaminated with metal-bearing acidic wastewater
and solvents, mostly originating from a chemical cleaning
facility. The site has four distinct underlying strata. The field
test was targeted at treating contamination in a relatively
permeable sand and gravel layer, approximately 30 ft below
ground surface (bgs). Testing revealed lateral heterogeneities in
the area between the two wells. Pre-demonstration testing
indicated concentrations of TCE up to 1,800 mg/L. Tc99
activities were measured up to 926 picocuries per liter (pCi/L).
Technology Application
Two horizontal wells 234 ft long were installed at a depth of 32
ft using directional drilling methods. The wells were placed
along the bedrock surface in a 3- to 7-ft-thick zone of a
moderately permeable, unconsolidated fluvial deposit. The
horizontal sections of the wells were constructed with ductile,
porous polyethylene. A network of 14 monitoring wells was
used to assess the influence of the horizontal flow field both on
the subsurface hydraulics and the ground-water contaminants.
The first well extracted water to a treatment unit consisting of a
carbon and an iron filter on the ground surface. The filtered
water was then reinjected into the second well.
Field testing was performed for 74 days, during which more
than 580,000 gal of water were recirculated. The water was
pumped at a rate of 6 gpm, and hydraulic and tracer tests were
performed. Hydraulic tests of well performance showed that a
hydraulic gradient of 0.13, twice the magnitude in non-
pumping conditions, could be induced between the wells.
Treatment of the mixed contaminant stream was conducted
with zero-valence iron (Fe°) for removal of Tc99 and with
activated carbon for removal of TCE and other hydrocarbons.
16
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Results
The treatment concept, to treat an aqueous mixed waste
without producing another mixed waste, was successfully
demonstrated. All of the Tc" in the more than 580,000 gal of
water was removed by approximately 12 in of coarse iron
particles. Because Fe° also slowly reduces TCE, the remaining
solid waste was not mixed waste by project's end. After storage
for a few days, the residual TCE was degraded leaving only the
Tc" on the Fe°. During operation, TCE was removed by the
carbon following passage through the Fe°. Because the water
no longer contained Tc" after flowing through the Fe°, the
waste carbon could be handled as a hazardous waste with no
concern for radioactivity.
The approximately $1.43M in design and construction funds
for this field demonstration were provided by two offices in the
Department of Energy. Other costs are more difficult to
estimate since this project was part of a larger effort. Cost
estimate details are provided in the reports cited below.
Site-specific References
Korte, N.; Muck, M.; Kearl, P.; Siegrist, R.; Houk, T.;
Schlosser, R.; and Zutman, J. Field Evaluation of a Horizontal
Well Recirculation System for Groundwater: Field
Demonstration atX-701B Portsmouth Gaseous Diffusion
Plant, ORNL/TM-13529, Oak Ridge National Laboratory,
Grand Junction, Colorado, June 1997
Korte, N.E.; Liang, L.; Gu, B.; Muck, M.T.; Zutman, J.L.;
Schlosser, R.M.; Siegrist, R.L.; Houk, T.C.; and Fernando, Q.
In Situ Treatment of Mixed Contaminants in Groundwater:
Application of Zero-Valence Iron and Palladized Iron for
Treatment of Groundwater Contaminated with Trichloroethene
and Technetium-99, ORNL/TM-13530, Oak Ridge National
Laboratory, Grand Junction, Colorado, April 1997
Muck, M.T.; Kearl, P.M.; Siegrist, R.L.; Korte, N.E.;
Schlosser, R.M.; Mumby, M.E.; Davenport, D.T.; Greene,
D.W.; Pickering, D.A.; and Muhr, C.A. Field Evaluation of a
Horizontal Well Recirculation System for Groundwater
Treatment: Pilot Test at the Clean Site, Portsmouth Gaseous
Diffusion Plant, ORNL/TM-13531, Oak Ridge National
Laboratory, March 1997
17
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Installation Date:
1996
Contaminants:
TCE, PCE
Enhancement:
Under consideration
Soil Type:
Sand
Point of Contact:
Roger White
Westinghouse Savannah River
Company
Bldg 773-42A
Aiken, SC 29808
Tel: 803-725-1314
Fax: 803-725-7673
E-mail: roger.white@srs.gov
Westinghouse Savannah River Site, Aiken, SC
A field demonstration of airlift recirculation wells (ARW) for
remediation of trichloroethene (TCE) and tetrachloroethene
(PCE) in ground water was installed at the Savannah River
Site, in Aiken, South Carolina, in 1996.
Site Background
The site once held metal finishing operations, which used
chlorinated solvents for cleaning and degreasing activities.
Discharges created a contaminant plume. Depth to ground
water is approximately 100 ft below ground surface (bgs).
Pump-and-treat technology was initiated in 1983 to contain and
remediate the central portion of the plume nearest the source of
contamination. Outlying portions of the plume continue to
migrate with the natural flow of the ground water. The southern
edge of the plume is in a confined aquifer approximately 54-ft
thick and consisting of fine- to medium-grained sand. The
horizontal and vertical conductivities are 25.8 ft/d and 1.43
ft/d, respectively. Initial pre-treatment sampling at one well
indicated TCE concentrations in excess of 10 mg/L. Since the
plume exists in a stratified configuration, concentrations
throughout the plume are uneven.
Technology Application
Two 8-in diameter recirculation wells were installed to a depth
of approximately 175 ft. Each well has a 10-ft inlet screen at
the bottom of the aquifer and a 10-ft discharge screen at the top
of the aquifer. An airlift pump was installed in each well with
an inflatable packer to isolate the wells' upper and lower screen
zones. A duplex, oil-free air compressor package provides air
for the pumps. A piezometer cluster was installed upgradient
and downgradient of each well. Five additional clusters have
subsequently been installed at the well that continues to
operate.
Results
Initial data obtained from each of the wells after the first few
months of operation indicated equipment and utility problems.
Review of hydrologic data indicated that the upper screens
were probably plugged after only a few weeks of operation. As
a result, a decision was made to focus on only one of the wells.
After carefully redeveloping that well, performance appears to
be very good. Recent sampling data indicate that over the past
14 months, TCE concentrations have been reduced by approxi-
mately 30-80% within the roughly 300-ft zone of influence.
18
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Exhaust stream measurements have confirmed that TCE is
being stripped from the ground water at a rate of 1 to 2 Ibs/day.
Ten additional wells are currently being installed between the
two existing wells with startup planned for December 1998.
Supplemental technologies aimed at enhancing the stripping
efficiency of the wells are under study.
The cost of the recirculation wells has been about $100K per
well, including the design of the installation and the need to
extend electrical power to the area.
Site-specific References
White, R.M. and Hiergesell, R. A. Airlift Recirculation Well
Test Results - Southern Sector (U), Westinghouse Savannah
River Company, Aiken, South Carolina, 1997
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EPA Superfund Sites
Installation Date:
1995
Contaminants:
PAHs
Enhancement:
Microorganisms, bioreactor
Soil Type:
Sand
Points of Contact:
Barry Spargo
Code6115NRL
Washington, DC 20375
Tel: 202-404-6392
Fax:202-404-8515
E-mail:
bspargo@ccf.nrl.navy.mil
Jim Mueller
Dames & Moore
1701 Golf Road, Tower 1
Suite 1000
Rolling Meadows, IL 60008
Tel: 847-228-0707
Fax: 847-228-1328
E-mail: chijgm@dames.com
Cabot/Kopper's Superfund Site, Gainesville, FL
A vacuum vaporizer well (UVB™-400) and an in situ
bioreactor for the remediation of polycyclic aromatic
hydrocarbons (PAHs) in soil and ground water were installed at
Cabot/Kopper's Superfund Site in Gainesville, Florida, in
1995.
Site Background
This Superfund site held both a pine tar and charcoal genera-
tion facility and a wood treatment facility. The source of the
contamination was the creosote used in the wood treating
operation. The plume is 110 ft wide x 500 ft long. The soil is
93% sand with some silt and clay. Remedial investigation
results indicated that ground water in the shallow aquifer (10 to
23 ft below ground) had been impacted. Horizontal and vertical
conductivities were 9xlO"3 cm/s and 9xlO"4 cm/s, respectively.
The horizontal gradient was 0.00625. Initial total
concentrations of PAHs in the soil exceeded 700 mg/kg.
Average total concentrations of PAHs in ground water for all
wells tested ranged from 5-50 mg/L.
Technology Application
A single UVB™ well and in situ bioreactor were installed at a
depth of 25 ft, downgradient from a lagoon area that had been
identified as a potential source of creosote constituents. Twelve
new monitoring wells were installed to supplement three
existing wells. A schedule of weekly monitoring, and quarterly
sample analysis of soil, ground water, and gas were established
over a two-year period.
Results
The system was started in February 1995 and continues to
operate into 1998, having been taken over by the client.
Samples taken after 18 months of operation indicated total
PAH concentrations of 10-35 mg/L in upgradient wells.
Concentrations in downgradient wells were measured at 0.04-2
mg/L. In 1997 phosphate and nitrogen were added directly into
the UVB™ to stimulate microbial activity within the zone of
influence. Particular nitrogen and phosphate species were
determined to be limiting in this biological system. Results of
this supplemental study have not been conclusive.
20
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The cost of this remediation was approximately $255K. This
included approximately $8K for mobilization, $85K for
monitoring, sampling, testing and analysis, $3K for site work,
$129K for equipment related costs, $4K for demobilization,
and $26K for administration. According to vendor estimates, a
similar system would run approximately $50K less in 1998.
Site-specific References
Spargo, B. J. (ed.) In Situ Bioremediation and Efficacy
Monitoring, Naval Research Laboratory, Washington, DC
Report No. NRL/PU/6115-96-317, 1996
Mueller, J.; Lakhwala, F.; Carter, J.; Spargo, B.; and Brourman,
M. Economics and Performance ofUVB Technology at a
Creosote Site, Battelle, First International Conference on
Remediation of Chlorinated and Recalcitrant Compounds,
Monterey, California, May 1998
Installation Date:
1994
Sweden-3 Chapman Superfund Site, Sweden, NY
A pilot-scale field demonstration of a microbiologically
enhanced vacuum vaporizer well (UVB™-400 system) for the
remediation of chlorinated and nonchlorinated hydrocarbons in
soil was conducted at the Sweden-3 Chapman Superfund Site
in Sweden, New York, from July 1994 to October 1995. An in
situ bioventing system and ex situ biovault treatment process
were also tested.
Contaminants:
Acetone, DCE, TCE, PCE,
MEK, and MIBK
Enhancement:
Bioreactor
Soil Type:
Silt/clay, sand, gravel
Points of Contact:
James Harrington, P.E.
New York State Dept. of
Environmental Conservation
Room 268
Site Background
The site is an inactive landfill that was used to dispose of
construction and demolition debris and hazardous waste. The
soil composition is heterogeneous with 19% gravel, 24% sand,
and 57% silt/clay. The seasonal water table fluctuates between
8 and 10 ft below ground surface (bgs). The average horizontal
hydraulic conductivity ranged from 3.3xlO"6 to 2.3xlO"7 ft/s,
and the average gradient was 0.054. Preliminary site
investigations indicated that the soil and ground water were
contaminated with a host of compounds. This demonstration
examined trichloroethene (TCE), dichlorethene (DCE),
tetrachloroethene (PCE), acetone, methylethyl ketone (MEK),
and 4-methyl 2-pentanone (MIBK). Pre-treatment data
available from EPA and the state, indicate that average initial
concentrations in soil were 6,967 |ig/kg acetone, 14,554 |ig/kg
MEK, 2,471 jig/kg MIBK, 653 |ig/kg PCE, 2,245 TCE, and
2,322 jig/kg total DCE.
21
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50 Wolf Road
Albany, NY 12233-7010
Tel: 518-457-0337
Fax:518-457-9639
E-mail:
jbharrin@gw. dec. state .ny.us
Prof. Scott Weber
New York State Center for
Hazardous Waste Management
State University at Buffalo
Jarvis Hall
Buffalo, NY 14260
Tel: 716-645-3446x2331
Fax: 716-645-3667
E-mail:
sweber(3>acsu .buffalo. edu
Technology Application
The system was installed in a 50 x 50 ft test plot. It consisted of
a 1.4 ft inner-diameter steel treatment well set at a depth of
25.9 ft bgs. A fixed packer was installed at a depth of 22 ft to
isolate the upper from the lower screen. Water was pumped
from the lower screen and discharged to an in situ bioreactor.
An aerator/stripper with an above-ground ambient air intake
pipe was attached to the outlet of the bioreactor to volatilize
contaminants. Offgases were extracted by a blower at the top of
the well and treated using gas phase bioreactors inoculated with
bacterium followed by granular activated carbon drums. Six
shallow and seven deep monitoring wells were installed around
the UVB™ well, and two wells were installed within the
annulus of the UVB™ well. Shallow wells were installed to a
depth of 12 ft and deep wells to 22 ft bgs. Ten ground-water
sampling events, from all 15 monitoring wells, were conducted.
Five soil sampling events, with 25 soil borings performed per
event, were also conducted.
Results
Both decreases and increases in concentrations of target VOCs
were observed in ground water. The UVB™ system generally
was effective in treating ground-water contamination based on
the VOC reductions observed. Ground-water VOC removals
generally decreased with distance from the well and were
higher in the shallow wells than in the deep wells. However,
actual ground-water data are not available in the EPA or state
reports since evaluation of ground-water treatment was beyond
the scope of this demonstration which was intended to evaluate
bioremediation treatments of vadose zone soils contaminated
with volatile organic compounds. With regard to soil, this
demonstration did not meet its goal which required that 90% of
the samples collected be in compliance with the state's
published acceptable concentrations. Only 70% of the soil
samples met the criteria at the end of the demonstration. At the
outset of the demonstration, the calculated compliance rate was
67%.
The cost of the initial 5-month demonstration was
approximately $153K. Of this, $15K was allocated for
mobilization, $6 IK for operational costs of the first half the
treatment, $3 IK for the second half of treatment, $15K for
decontamination and demobilization, and $3 IK for the final
report. Approximately $82K was added to the project to extend
it for an additional 7 months. This does not include sampling
and analysis provided by EPA's Superfund Innovative
Technology Evaluation (SITE) program.
22
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Site-specific References
Kufel, Todd and Weber, A.S. "Analysis of the New York State
Demonstration of Bioremediation Technology at the Sweden-3
Chapman Site," New York State Center for Hazardous Waste
Management, State University of New York at Buffalo, August
1996
Lakhwala, Fayaz S.; Mueller, J.G.; and Desrosiers, RJ.
"Demonstration of a Microbiologically Enhanced Vertical
Ground Water Circulation Well Technology at a Superfund
Site," Ground Water Monitoring Review, p 97-106, Spring
1998
Weber, A. Scott, "Multi-Vendor Bioremediation Technology
Demonstration Project," 4th International Conference for Site
Investigation for Hazardous Sites, London, England, October
3-4, 1995
23
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Private Commercial Sites
Installation Date:
1992
Contaminants:
TPH, benzene, toluene,
ethylbenzene, xylene,
naphthalene
Enhancement:
Not applicable
Soil Type:
Silty sands, gravel, clay
Point of Contact:
Shelley Quick
Utah Dept of Water Quality
288 North 1460 West
Salt Lake City, UT 84116
Tel: 801-538-6516
Fax: 801-538-6016
E-mail: squick@deq.state.ut.us
Amcor Precast, Ogden, UT
A Density Driven Convection (DDC) system for the remedia-
tion of fuel hydrocarbons was installed at Amcor Precast in
Ogden Utah, in 1992. It was part of system that also contained
a ground-water pumping and reinjection system and a soil
vapor extraction system.
Site Background
Amcor Precast operated three underground storage tanks used
for gasoline and diesel fuel. Release of contaminants was
discovered when the tanks were removed for permanent
closure. At that time, the spill had impacted an estimated 6,700
yd3 of soil. The stratigraphy consisted of silty sands, fine
gravel, and a silty clay aquitard at about 18 ft below ground.
Hydraulic conductivity was measured at 190 ft/d. Contaminants
were concentrated within a zone from about 5 to 11 ft below
ground. Maximum pre-remediation concentrations of total
petroleum hydrocarbons (TPH) were measured at 1,600 mg/kg
in the soil and 190 mg/L in the ground water. Average
concentrations in the plume were 555 mg/kg in the soil and 51
mg/L in the ground water. Total concentrations of benzene,
toluene, ethylbenzene, xylene, and naphthalene were measured
at maximums of 139 mg/kg in soil and 25 mg/L in ground
water, with averages in the plume of 46 mg/kg and 7 mg/L,
respectively.
Technology Application
The system consisted of three principal components—a DDC
system, a ground-water pumping and reinjection system, and a
soil vapor extraction system. The DDC system consisted of 12
wells installed to a depth of 18 ft each connected via
underground lines to a pressurized air supply source and each
having a separate air injection line. During operation, air
injection rates were maintained at between 60-100 standard
cubic feet per minute (scfm). The ground-water pumping and
reinjection system consisted of three downgradient extraction
wells installed to a depth of 20 ft and one upgradient injection
gallery. Pressurized air supply lines for extraction and water
lines for conducting pump discharge to the gallery were placed
below ground. The total extraction rate for all three wells was
maintained at 10 gpm. The soil vapor extraction system
consisted of three vertical vapor extraction wells located
adjacent to the downgradient ground-water extraction wells.
They were connected via underground lines to a vacuum
24
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blower motor. Total soil vapor extraction rates were maintained
at 70-90 scfm. Soil concentrations were measured 11 months
after startup. System operation and ground-water monitoring
was continued for an additional 7 months.
Results
The system ran from March 1992 to September 1993. Final
concentrations of TPH in the soil from the plume area averaged
1.6 mg/kg, with a maximum of 6.3 mg/kg. Final concentrations
of TPH in ground water averaged 0.71 mg/L, with a maximum
of 1.3 mg/L. Similar reductions were achieved for benzene,
toluene, ethylbenzene, xylene, and naphthalene.
The cost of this remediation was approximately $157K for
capital costs and project management and $63K annually for
operations and maintenance.
Site-specific References
Wasatch Environmental, Inc. Density-Driven Groundwater
Sparging at Amcor Precast, Ogden, Utah, final report prepared
for the U.S. Army Corps of Engineers, Omaha District, July
1994
Former Service Station, Commerce City, CO
Installation Date: A full-scale application using a system of air and ozone
1997 injection with vertical circulation of ground water (C-
Sparge™) in combination with a vacuum extraction system
was administered at a former service station site in Commerce
City, Colorado, in 1997. It was designed to remediate soil and
„ , , ground water contaminated with petroleum hydrocarbons and
Contaminants: ° j , /f>T^^ ™.
TPH BTEX benzene, toluene, ethylbenzene, and xylene (BTEX) The
addition of ozone to the circulation well serves to oxidize the
contaminants in the subsurface.
Enhancement: Site Background
Ozone The site, which once served as a bulk storage and service
station facility, currently is part of a metal recycling facility.
Subsurface material consists of sand and gravel mixtures to a
depth of approximately 43 ft below ground surface (bgs),
01 ype. grading to a blue clay. Ground water is approximately 28 ft
band-gravel mix . _ ,, . . . ,, . .,,,,.
bgs. Because of the composition of the soil hydraulic
conductivity tests were deemed unnecessary. A soil and
ground-water investigation indicated that total petroleum
hydrocarbons (TPH) in the soil ranged from 90-2,380 mg/kg.
Total BTEX in soil ranged from 7,800-36,550 |ig/kg. TPH in
25
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Point of Contact:
Gordon Davitt
Moiety Associates
1080 Fifth Street
Penrose, CO 81204
Tel: 719-372-6970
Fax: by appointment
E-mail: moietyrands@juno.com
the ground water ranged from free product to 490 mg/L and
BTEX ranged from 22-2,260 |ig/L. Concentrations of benzene,
the contaminant by which the cleanup standard of 5 |ig/L is
measured, ranged from non-detectable to 16 |ig/L.
Technology Application
Two C-Sparge™ panels, each operating three wells, were
installed. Each well consisted an in-ground sparge point, which
blows ozone and air into the ground water, an in-well sparge
point which blows water in the well casing, a pump to generate
circulation, and a packer. Each well boring was advanced to a
depth of 50 ft bgs. The well was sealed from a depth of 10 ft to
the ground surface. The panels were installed in an outside
area, open to the weather. Sparge point pressures ranged from
14-20 pounds per square inch (psi) depending on the distance
from the well to the panel. The system was augmented with a
large blower pulling 160 ft 3/min (cfm) at 48-in vacuum water
column. The entire system ran through 12 complete cycles per
day. Each cycle involved all six wells blowing ozone and air
into the ground water, blowing the water into the casing, and
pumping. Each cycle lasted approximately 25 minutes. The
blower unit operating constantly.
Results
The system started in August 1997 with quarterly monitoring.
The March 1998 results showed a concentration of 37 mg/L
TPH in the well that previously contained free product. No
TPH or BTEX was detected in any other of the monitoring
wells, so the remediation system was turned off. Monitoring
results in June and September 1998 indicated that levels remain
below the state maximum contaminant levels for drinking
water (MCLs). The state did not require confirmatory soil
borings. Quarterly sampling is required for a year following the
sytem's shutdown in March 1998.
The anticipated cost of the demonstration from site
investigation through completion of final monitoring is
approximately $160K. Of this, approximately $20K was
allocated for site investigation, $55K for equipment, $35K for
installation, and $15K for sparge wells.
Site-specific References
Not available
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Installation Date:
1995
Contaminants:
TPH, benzene, toluene,
ethylbenzene, xylene, and
naphthalene
Enhancement:
Not applicable
Soil Type:
Silty clay, gravel
Points of Contact:
Bruce Hagans / Dale Urban
Utah Department of
Environmental Quality
DERR
168 North 1950 West
Salt Lake City, UT 84116
Tel: 801-536-4174 (Bruce)
Tel: 801-536-4145 (Dale)
Fax: 801-359-8853
E-mail:
bhagans@deq. state .ut.us
durban@deq.state .ut.us
Top Stop Store, Park City, UT
A Density Driven Convection (DDC) system for the
remediation of fuel hydrocarbons was installed at the Top Stop
Service Station in Park City, Utah, in 1995.
Site Background
Soil and ground water at the site were contaminated by a
release of gasoline from an old underground storage tank
fueling system. The contamination impacted the shallow
unconfmed aquifer, which is used as a back-up water supply to
the city and discharges to a wetland and stream. Soils at the site
consist of silty clay, gravel, and cobbles. Depth to the water
table varies seasonally from 15 to 20 ft. Pre-treatment
concentrations of total petroleum hydrocarbons (TPH)
averaged approximately 30 mg/L, and total concentrations of
benzene, toluene, ethylbenzene, xylene, and napthalene
averaged 2 mg/L.
Technology Application
An 18-well DDC system was installed along with five soil
vapor extraction (SVE) wells to treat vadose zone contamina-
tion. The wells were screened at 10-20 ft below ground surface
(bgs) and at 25-30 ft bgs. They were spaced 30-35 ft apart. Five
monitoring wells, interspersed around the site, were sampled to
evaluate contaminant concentrations within and downgradient
of the plume. Samples were taken quarterly.
Results
The average dissolved contaminant concentrations within the
plume have been reduced more than 99% in just over 2 years of
operation. Early 1998 samples indicate no detectable
concentrations of either TPH or benzene, toluene,
ethylbenzene, xylene, and napthalene. Furthermore, no
contamination was detected in downgradient wells after the
system became operational.
The cost of this remediation was approximately $99K for
equipment installation (including the thermal catalytic oxidizer,
only used in the first year to treat the vapors), $34K for first-
year operations and maintenance (O&M), and $12K for
second-year O&M.
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Site-specific References
DeHart, T.; Pennington, L; and Urban, D. "Operation of In-
Well Aeration and Soil Vapor Extraction Remediation
Systems," U.S. EPA Region VUI Corrective Actions
Conference, Salt Lake City, Utah, August 1997
Installation Date:
1997
Dry Cleaning Facilities, Hutchinson, KS
A pilot test using two different in-well stripping processes for
remediation of tetrachloroethene (PCE) in ground water was
conducted in Hutchinson, Kansas, in 1997. This pilot was part
of a test involving three similar locations within the city to
evaluate three different technologies: air sparging with soil
vapor extraction (AAS/SVE), ozone and air injection with
vertical circulation of ground water (C-Sparge™), and in-well
stripping (NoVOCs™)
Site Background
All three test sites were located near former or existing dry-
cleaning facilities within the city limits. Underlying sediments
consist of unconsolidated stream and terrace deposits (sand,
silt, and clay). The water table is from 14-16 ft below ground
surface (bgs). The hydraulic conductivity value calculated at
one location was estimated at 500-770 ft/d with a general
hydraulic gradient of 0.001. Dissolved-phase PCE appeared
limited to the top 15 ft of the aquifer with maximum
concentrations ranging from 30-600 |ig/L.
Technology Application
Each test configuration consisted of an above-ground
remediation system in a temporary enclosure or trailer, a single
or combination remediation well configuration, above- and
below-grade piping, and ground-water monitoring wells. The
placement of monitoring wells varied for each site to
accommodate the technology-specific data collection
requirements.
Contaminants:
PCE
Enhancement:
Ozone
Soil Type:
Sand, silt, clay
Points of Contact:
Leo G. Henning
Kansas Dept. of Health &
Environment
Bldg 740 at Forbes Field
Topeka, KS 66620
Tel: 785-296-1914
Fax: 785-296-4823
E-mail:
lhenning@kdhe. state .ks .us
Douglas Dreiling
Burns & McDonnell
3839 Dora
Wichita, KS 67213
Tel: 316-941-3921
Fax:316-941-4730
E-mail: ddrel@burnsmcd.com
http://www.burnsmcd.com
The NoVOCs™ system included an 8-in diameter PVC
remediation well installed to a depth of 38 ft with one stainless
steel screen bracketing the water table and one fully in the
saturated zone. The system was also equipped with an air
diffuser and an infiltration gallery. Four monitoring wells were
constructed to a total depth of 35 ft bgs at distances of 30-80 ft
from the remediation well. Air was injected into the
remediation well at a rate of approximately 70-95 standard
28
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cubic feet per minute (scfm) and the flow rate through the well
was approximately 40 gpm.
The C-Sparge™ system involved a 4-in diameter PVC
remediation well installed to 35 ft bgs with a micro-porous
sparge point placed in the lower part of the borehole. The well
was screened in the vadose and saturated zones. A self-
contained down-hole unit, including a second sparge point and
fluid pump, was installed in the casing. Ground-water
information was collected from a cluster of five monitoring
wells. The average rate of injection was 3 scfm. This
technology is enhanced by the addition of ozone (O3) to oxidize
the contaminants. It further differs from NoVOCs™ treatment
in that the reaction takes place in the formation instead of in the
well, thereby treating PCE in both the saturated soil and ground
water as opposed to only treating the ground water.
Results
Pilot test activities for all sites were conducted over a 5-month
period and included monitoring well and system installation,
pre-test ground-water sampling, a 6-day system start-up period,
on-going data collection and operation and maintenance, and
post-test ground-water sampling.
Monitoring wells 30 ft from the remediation well using
NoVOCs™ indicate an 87% reduction in concentration of
PCE, from 39-5 |ig/L. C-Sparge™ resulted in a 91% reduction
from 34 to 3 //g/L, and AAS/SVE resulted in a 66% reduction
from 489 to 168//g/L.
This field demonstration cost approximately $195K, of which
$95K was for the NoVOCs™ test and $52K was for the C-
Sparge™ test. A cost comparison indicated that the AAS/SVE
system was the least expensive to install and the C-Sparge™
most economical to operate. The NoVOCs™ was the most
expensive to install and operate.
Site-specific References
Dreiling, D. N.; Henning, L.G.; Jurgens, R.D.; and Ballard,
D.L. "Multi-Site Comparison of Chlorinated Solvent
Remediation Using Innovative Technology," Battelle, First
International Conference on Remediation of Chlorinated and
Recalcitrant Compounds, Monterey, California, May 1998
29
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Installation Date:
1996
Contaminants:
PCP
Enhancement:
Not applicable
Soil Type:
Silty sand, clay, gravel
Point of Contact:
Andrew Kopania
EMKO Environmental
2329 Shortlidge Ct.
El Dorado Hills, CA 95762
Tel: 916-939-0133
Fax: 916-939-0529
E-mail: akopania@aol.com
Wood Treatment Site, Denver, CO
A pilot study of Density Driven Convection (DDC) for the
remediation of pentachlorophenol (PCP) was conducted at a
wood treatment site in Denver, Colorado, in 1996.
Site Background
The contamination at this site impacts ground water across two
distinct aquifer units with substantially different hydraulic
conductivities. Conductivity in the upper zone was measured at
5xlO"3 cm/s and at 5xlO"5 cm/s in the lower zone. The upper
unit is approximately 15 ft of interbedded silty sand, silty clay,
and gravel, and the lower unit is an approximately 10-ft thick
claystone layer. The water table is about 13 ft below ground.
Pre-treatment sampling indicated PCP concentrations of 1,600
Technology Application
The pilot was conducted in an off-site portion of the plume.
Two ground-water circulation wells (GCW) were installed to
depths of approximately 25 ft. Each well had two piezometers
within the borings. In addition, two piezometer pairs were
placed 5-15 ft away from each of the GCWs in both the
shallow and deep aquifer units. The wells pumped non-stop for
the duration of the test. A dye tracer test was performed over
the period of the demonstration to determine the radius of
influence.
Results
The pilot ran from December 1996 through March 1997. After
84 days of operation, PCP concentrations were reduced by 43%
to approximately 900 |ig/L. The dye tracer was detected at least
15 ft from the wells after 7 days of operation. The tracer was
found in all monitoring points in both aquifer units.
A containment wall currently is being installed to contain free
product. In addition, a DDC system is being investigated to
remediate the dissolved phase plume.
The cost of this pilot was approximately $80K.
Site-specific References
Not applicable
30
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General References
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Chen, L. and Knox, R.C. "Using Vertical Circulation Wells for Partitioning Tracer Tests and
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Dawson, G.W. "Innovative Approaches to Remediation for VOC Sites Using Recirculating
Wells," Sixth Annual West Coast Conference on Contaminated Soils and Groundwater,
Newport Beach, California, March 11-14 1996.
Dawson, G.W.; McKeon, T.J.; and Hawk, T.S. "In-Well Treatment for Remediation of VOCs in
Ground-water," I&EC Symposium, American Chemical Society, Atlanta, Georgia,
September 17-20 1995.
Dawson, G.W. "In-Well Treatment of Remediation of VOCs in Ground Water," Defense Waste
Cleanup Conference, Washington, DC, October 4, 1994.
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Gilmore, TJ. and Francois, O. Laboratory Testing of the In-Well Vapor-Stripping System,
Battelle Pacific Northwest Laboratory, Richland, Washington, March 1996.
Gilmore, T.J.; Kaplan, D.I.; and Oostrom, M. "Residence Times Required for Chlorinated
Hydrocarbon Degradation by Reactive Wells," Battelle, First International Conference on
Remediation of Chlorinated and Recalcitrant Compounds, Monterey, California, May
1998.
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