United States Solid Waste and EPA 542-R-98-009

Environmental Protection Emergency Response October 1998

Agency (5102G) http://www.epa.gov/swertio1

http://clu-in.org

Field Applications of In Situ

Remediation Technologies:

Ground-Water Circulation

Wells
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
ii

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.
iii

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 (“pumpand-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 contamination. 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
iv
v

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
vi
1

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.
2

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
3

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 NoVOCsTM, UnterddruckVerdampfer-Brunnen (UVBTM) or “vacuum vaporized well,” Density Driven Convection (DDC),

and C-SpargeTM.

NoVOCsTM 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 UVBTM 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-SpargeTM 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.
Department of Defense Sites 

4

Edwards Air Force Base, CA

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 2650A

Edwards AFB, CA 93524-1130

Tel: 805-277-1474

Fax: 805-277-6145

E-mail:

steckeld%em@mhs.elan.af.mil

A field demonstration of in-well vapor stripping (NoVOCsTM)

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 1ft/d with a vertical gradient of 0.1. The

horizontal conductivity is 10ft/d with a gradient of 0.005.

Previous investigations identified the maximum concentration

of TCE in the area to be 502 μg/L; the average concentration

was 300 μg/L. Maximum concentrations upgradient of the

demonstration site were as high as 3,400 μg/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
5

operated nearly continuously for 191 days. Pumping rates of

water pushed through the well via lifting (7-10 gpm) and airinjection 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 μg/L to below the regulatory

limit of 5 μg/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 μg/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 Installation 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
6

White, M.D., and Gilmore, T.J. Numerical Analysis of the InWell Vapor-Stripping System Demonstration at Edwards Air

Force Base, Pacific Northwest National Laboratory, Richland,

Washington, 1996

Keesler Air Force Base, MS

Installation Date:

1995

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

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, unconfined aquifer with ground water at approximately 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 groundwater 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 fullscale 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
7

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 lbs, 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 downgradient 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 offsite.

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 Technology Demonstration, Keesler Air Force Base, AOC A (ST06), BX Service Station, U.S.EPA I.D. #MS2 570 024 164,

Biloxi Mississippi, prepared for the Air Force Center for

Environmental Excellence, Brooks Air Force Base, Texas, July

1998
8

March Air Force Base, Riverside, CA

Installation Date:

1993

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

A field demonstration of a UVBTM ground-water recirculating

well for remediation of trichloroethene (TCE) was conducted at

March Air Force Base, California between 1993-1994.

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 μg/L with an average of 500 μg/L.

Technology Application

Prior to installing the UVBTM well, a pilot boring was installed

to a depth of 118.5 ft bgs to characterize stratigraphy. The

UVBTM treatment well was drilled to a depth of 87.5 ft. Three

monitoring wells were installed within the UVBTM borehole,

one screened across the influent section and two at 901

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

UVBTM well. The clusters consisted of discretely-screened

shallow, intermediate, and deep wells. A vadose zone well was

installed 60 ft from the UVBTM 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, groundwater sampling, and analysis. 

Results

EPA’ Superfund Innovative Technology Evaluation Program

reports that, over the 18 months of operation, TCE concentrations averaged 250 μg/L, varying from 47 to 270 μg/L.

Influent TCE concentrations in the lower screen varied between

non-detectable and 320 μg/L throughout the study, averaging

30 μg/L. Occasional influent values that were greater than 30

μg/L indicated mechanical problems with the system. Effluent

concentrations varied between non-detectable and 15 μg/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 UVBTM well was approximately

$180K. First year operations and maintenance (O&M) costs
9

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 UVBTM 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.; and Dominick,

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-VerdampferBrunnen Technology (UVB) Vacuum Vaporizing Well,”

EPA/540/R-95/500a, July 1995

 Massachusetts Military Reservation, Cape Cod, MA

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

A field demonstration of two ground-water recirculating well

configurations (NoVOCsTM and UVBTM) 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).

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 groundto-air missiles and armored and wheeled vehicles. Pre-pilot test

data indicated maximum TCE concentrations of 2,800 μg/L in

ground water, with lower concentrations of other chlorinated

solvents, hydrocarbons, and metals.
10

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 UVBTM 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 UVBTM 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

UVBTM test area.

The NoVOCsTM 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, crossgradient, downgradient, and near-field locations and three

piezometers were used to monitor circulation cell development

at the NoVOCsTM 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 (UVBTM), 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 UVBTM system indicated effluent

concentrations did not reach the target of 1 μg/L. TCE

concentrations in ground water near the upper effluent screen

remained relatively constant at approximately 100 μg/L.

Middle zone or influent TCE concentrations dropped from

approximately 600 to 180 μg/L. However, upgradient

concentrations, outside the zone of influence of the wells, also
11

dropped from approximately 400 to 150 μg/L during the same

period. Lower zone TCE concentrations corresponding to the

lower effluent screen remained nearly constant throughout the

period at 200 μg/L. Results from the NoVOCsTM system also

indicated effluent concentrations did not reach the target of 1

μg/L. TCE in the reinjection zone was reduced from 2,700

μg/L to approximately 100 μg/L, while concentrations in the

extraction zone remained stable at approximately 1,300 μg/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 UVBTM system, and 84 kg of VOCs

have been removed by the 300 -gpm NoVOCsTM system.

Effluent concentrations for the UVBTM system have generally

been below the maximum contaminant level (MCL) of 5 μg/L

for TCE. Effluent concentrations for the NoVOCsTM system

have generally been in excess of the MCL since initiation of the

pilot test. However, background levels for TCE are higher at

the NoVOCsTM site (approximately 1,000 μg/L) than at the

UVBTM site (about 550 μg/L). Average stripping efficiency was

95.5% for the UVBTM system and 91% for the NoVOCsTM

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, $331K 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 of Groundwater

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
12

International Conference on Remediation of Chlorinated and

Recalcitrant Compounds, Monterey, California, May 1998

Dwight, D. M.; Mantovani, P.F.; and English, J. “Pilot

Recirculating Well System (NoVOCsTM) 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:

1995

Contaminants:

BTEX

Enhancement:

Not applicable

Soil Type:

Silty sand, sand

A field demonstration of ground-water circulating wells

(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

are variations of the UVBTM technology.

Site Background

The site is a former gasoline station which was contaminated

with approximately 11,000 gallons of gasoline that leaked from

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

the upper perched aquifer. The depth to ground water is

between 3.3-12.1 ft bgs. The horizontal hydraulic conductivity

was measured at 3.84x10-2 cm/s, and the vertical hydraulic

conductivity at 3.84x10-3 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.
13

Point of Contact:

Barry Spargo

Code 6115 NRL

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 (GCW400) 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 ft bgs and 21.8-26.3 ft bgs,

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 μg/L. BTEX concentrations in the ground water from

the deep wells were reduced from 118 mg/L to under 1 μg/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 

Tyndall Air Force Base, FL

Installation Date:

1994

A field demonstration of a modified coaxial ground-water

circulating (mKGB) system coupled with a modified bioventing well (MBW) system for remediation of hydrocarbons

in both the saturated and unsaturated zones was performed in a
14

Contaminants:

TPH

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

portion of a large plume at Tyndall Air Force Base, Florida,

from 1994-95.

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.
15

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
Department of Energy Sites

16

Portsmouth Gaseous Diffusion Plant, Piketon, OH

Installation Date:

1996

Contaminants:

TCE, TC99

Enhancements:

Fe0

, 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

A field-scale demonstration of horizontal recirculation wells

coupled with treatment modules for remediation of trichloroethene (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.

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 nonpumping conditions, could be induced between the wells.

Treatment of the mixed contaminant stream was conducted

with zero-valence iron (Fe0

) for removal of Tc99 and with

activated carbon for removal of TCE and other hydrocarbons.
17

Results

The treatment concept, to treat an aqueous mixed waste

without producing another mixed waste, was successfully

demonstrated. All of the Tc99 in the more than 580,000 gal of

water was removed by approximately 12 in of coarse iron

particles. Because Fe0

 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

Tc99 on the Fe0

. During operation, TCE was removed by the

carbon following passage through the Fe0. Because the water

no longer contained Tc99 after flowing through the Fe0, 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 at X-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 
18

Westinghouse Savannah River Site, Aiken, SC

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

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 approximately 30-80% within the roughly 300-ft zone of influence.
19

Exhaust stream measurements have confirmed that TCE is

being stripped from the ground water at a rate of 1 to 2 lbs/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
EPA Superfund Sites

20

Cabot/Kopper’s Superfund Site, Gainesville, FL

Installation Date:

1995

Contaminants:

PAHs

Enhancement:

Microorganisms, bioreactor

Soil Type:

Sand

Points of Contact:

Barry Spargo

Code 6115 NRL

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

A vacuum vaporizer well (UVBTM-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 generation 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 9x10-3 cm/s and 9x10-4 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 UVBTM 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 UVBTM 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.
21

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 of UVB Technology at a

Creosote Site, Battelle, First International Conference on

Remediation of Chlorinated and Recalcitrant Compounds,

Monterey, California, May 1998

Sweden-3 Chapman Superfund Site, Sweden, NY

Installation Date:

1994

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

A pilot-scale field demonstration of a microbiologically

enhanced vacuum vaporizer well (UVBTM-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.

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 3.3x10-6 to 2.3x10-7 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 μg/kg acetone, 14,554 μg/kg

MEK, 2,471 μg/kg MIBK, 653 μg/kg PCE, 2,245 TCE, and

2,322 μg/kg total DCE.
22

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: 716-645-3446 x 2331

Fax: 716-645-3667

E-mail:

sweber@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 UVBTM well, and two wells were installed within the

annulus of the UVBTM 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 UVBTM 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, $61K for operational costs of the first half the

treatment, $31K for the second half of treatment, $15K for

decontamination and demobilization, and $31K 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.
23

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, R.J.

“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
Private Commercial Sites

24

Amcor Precast, Ogden, UT

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

A Density Driven Convection (DDC) system for the remediation 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
25

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:

1997

Contaminants:

TPH, BTEX

Enhancement:

Ozone

Soil Type:

Sand-gravel mix

A full-scale application using a system of air and ozone

injection with vertical circulation of ground water (CSpargeTM) 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

benzene, toluene, ethylbenzene, and xylene (BTEX) The

addition of ozone to the circulation well serves to oxidize the

contaminants in the subsurface.

Site Background

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),

grading to a blue clay. Ground water is approximately 28 ft

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 μg/kg. TPH in
26

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 μg/L. Concentrations of benzene,

the contaminant by which the cleanup standard of 5 μg/L is

measured, ranged from non-detectable to 16 μg/L.

Technology Application

Two C-SpargeTM 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
27

Top Stop Store, Park City, UT

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 

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

unconfined 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 contamination. 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 firstyear operations and maintenance (O&M), and $12K for

second-year O&M.
28

Site-specific References

DeHart, T.; Pennington, L; and Urban, D. “Operation of InWell Aeration and Soil Vapor Extraction Remediation

Systems,” U.S. EPA Region VIII Corrective Actions

Conference, Salt Lake City, Utah, August 1997 

Dry Cleaning Facilities, Hutchinson, KS

Installation Date:

1997

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 

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-SpargeTM), and in-well

stripping (NoVOCsTM)

Site Background

All three test sites were located near former or existing drycleaning 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 μg/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.

The NoVOCsTM 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
29

cubic feet per minute (scfm) and the flow rate through the well

was approximately 40 gpm.

The C-SpargeTM 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 selfcontained 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 NoVOCsTM 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

NoVOCsTM indicate an 87% reduction in concentration of

PCE, from 39-5 μg/L. C-SpargeTM 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 NoVOCsTM test and $52K was for the CSpargeTM test. A cost comparison indicated that the AAS/SVE

system was the least expensive to install and the C-SpargeTM

most economical to operate. The NoVOCsTM 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
30

Wood Treatment Site, Denver, CO

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

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

5x10-3 cm/s and at 5x10-5 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

μg/L.

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 μg/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
31

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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.

Francois, O.; Gilmore, T.J.; Pinto, M.J.; and Gorelick, S.M. “A Physically Based Model for AirLift Pumping,” Water Resources Research, Vol. 32, No. 8, pp 2383-2399, 1996.

Gilmore, T.J. 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.

Gvirtzman, H. and Gorelick, S.M. “The Concept of In Situ Vapor Stripping for Removing VOCs

from Groundwater,” Transport in Porous Media, Vol. 8, No. 1, pp 71-92, 1992.
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Around Wells with Two Screen Sections for In Situ or On-Site Aquifer Remediation,” in

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Methods in Water Resources IX, Vol. 1, pp 483-493, Computational Mechanics

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Herrling, B.; Stamm, J.; Alesi, E.J.; Bott-Breuning, G.; and Diekmann, S. “In Situ

Bioremediation of Groundwater Containing Hydrocarbons, Pesticides, or Nitrate Using

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