1

EPA is committed to identifying the most effective and efficient means of addressing the thousands of hazardous

waste sites in the United States. Therefore, the Office of Solid Waste and Emergency Response’s (OSWER’s)

Technology Innovation Office (TIO) is working in conjunction with the EPA Regions and research centers and

with industry to identify and encourage the further development and implementation of innovative treatment

technologies.

One way to enhance the use of these technologies is to ensure that decision-makers are aware of the most current

information on technologies, policies, and other sources of assistance. This Guide was prepared to help identify

documents that can directly assist Federal and State site managers, contractors, and others responsible for the

evaluation of technologies. Specifically, this Guide is designed to help those responsible for the remediation of

RCRA, UST, and CERCLA sites that may employ technologies to enhance Soil Vapor Extraction (SVE). Information on SVE can be found in the Soil Vapor Extraction (SVE) Treatment Technology Resource Guide.

This Guide provides abstracts of over 90 SVE enhancement technology guidance documents, overview/program

documents, studies and demonstrations, and other resource guides. It also provides a brief summary of the SVE

enhancement technologies highlighted in the Guide. These technologies include air sparging, bioventing, hot air

injection, steam injection, electrical resistance heating, radio frequency heating, pneumatic fracturing, and hydraulic fracturing. For each type of technology, a matrix is provided to allow easy screening of the abstracted references.

To develop this Guide, a literature search was conducted using a variety of commercial and Federal databases

including the National Technical Information Service (NTIS) and Energy Science and Technology Databases.

The selected references are not an exhaustive list of all available literature, but rather a representative sample of

the available literature. Because of the inherent lag time between document publication and subsequent listing in

electronic databases, there may be more recent references available than those included in the Guide. Most of the

references in the Guide are of documents published between 1991 and 1994. The documents selected are available from suppliers such as EPA’s National Center for Environmental Publications and Information, NTIS,

document delivery services, and a variety of libraries. Information in this Guide does not represent an endorsement by EPA.

INTRODUCTION
2

When using this Guide to identify resource information on SVE enhancement technologies, you may wish to take

the following steps:

1. Turn to the Soil Vapor Extraction Enhancement Technology Resource Matrices located in the section

titled "Technology Summaries" on pages 4 through 12 of this Guide. These matrices list alphabetically by

document type over 90 SVE enhancement technology-related documents, identify the type of information

provided by each document, and provide a document ordering number.

2. Select the document(s) that appear to fit your needs based on the information in the matrices.

3. Check the abstract identification code. This number refers to an abstract of the document. The number

corresponds to a page number in the Guide and the letter corresponds to an abstract on that page.

For example:

4. Review the abstract that corresponds to the document in which you are interested to confirm that the document will fit your needs.

5. If the document appears to be appropriate, note the document number highlighted under the abstract. For

example:

[Note: Some documents do not have ordering numbers. These documents can be obtained through local,

technical, or university libraries.]

6. Turn to the section entitled "How to Order Documents Listed in this Guide" on page 3 of this Guide and order

your document using the directions provided.

HOW TO USE THIS GUIDE

Abstract

Identification

Code

: A

Page 13 in the

Resource Guide

Abstract A on

page 13 of the

Resource Guide

13

 EPA Document Number: EPA/540/S-92/003
3

HOW TO ORDER DOCUMENTS LISTED IN THIS GUIDE

Documents listed in this Guide are available through a variety of sources. When ordering documents listed in the

Soil Vapor Extraction Enhancement Technology Abstracts section of this Guide, use the number listed in the bar

below the document title, or refer to the journal or source indicated as part of the title. If using the Soil Vapor

Extraction Enhancement Technology Resource Matrices, use the number listed below the document title, or refer

to the journal or source indicated in the source column. If multiple document ordering numbers are identified,

select the appropriate number based on the directions below. EPA/540 and EPA/600 documents may be available

through the Center for Environmental Research Information (CERI); EPA/542 documents may be obtained

through the National Center for Environmental Publications and Information (NCEPI); and EPA/530 documents

may be obtained from the RCRA Information Center (RIC). These document repositories provide in-stock

documents free of charge, but document supplies may be limited. Documents obtained through the National

Technical Information Service (NTIS) are available for a fee; therefore, prior to purchasing a document through

NTIS, you may wish to review a copy at a technical or university library, or a public library that houses government documents.

Document Type Document Source

Publication numbers with the following prefixes: National Technical Information Service (NTIS)

5285 Port Royal Road

AD Springfield, VA 22161

DE (703) 487-4650

PB fax requests to (703) 321-8547

8:30 a.m. - 5 p.m., Eastern Time.

NTIS provides documents for a fee.

Publications with the following numbers: Center for Environmental Research Information

(CERI)

EPA/540 (limited collection) 26 West Martin Luther King Drive

EPA/600 Cincinnati, OH 45268

(513) 569-7562

fax requests to (513) 569-7585

8:00 a.m. - 4:30 p.m., Eastern Time

Out of stock documents may be ordered from NCEPI or may be purchased from NTIS.

Publications with the following numbers: National Center for Environmental

Publications and Information (NCEPI)

EPA/542 (limited collection) 11305 Reed Hartman Highway, Suite 219

Cincinnati, OH 45241

(513) 489-8190

fax requests to (513) 489-8695

7 a.m. - 5:30 p.m., Eastern Time.

A document title or number is needed to place an order with NCEPI.

Some out-of-stock documents may be purchased from NTIS.

Publications with the following numbers: RCRA Information Center (RIC)

401 M St., S.W. Mailcode: 5305

EPA/530 Washington, DC 20460

(202) 260-9327

9 a.m. - 4 p.m., Eastern Time.

If you have difficulty finding a document or wish to obtain EPA/510 documents, call:

RCRA/Superfund/OUST Hotline ............................ (800) 424-9346, (703) 412-9810, TDD: (800) 553-7672, (703) 412-3323

Operates Monday - Friday, 8:30 a.m. - 7:30 p.m., Eastern Time.

Hotline staff can help EPA staff or members of the public locate documents and assist callers with placing document orders.
4

TECHNOLOGY SUMMARY: AIR SPARGING

Air sparging, also referred to as in situ air stripping, is an in situ remediation

technology that involves the injection of air into the subsurface saturated zone

and venting through the unsaturated zone to remove subsurface contaminants.

During air sparging, air bubbles traverse horizontally and vertically through the

saturated and unsaturated zones, creating an underground stripper that removes

contaminants by enabling a phase transfer of hydrocarbons from a dissolved or

adsorbed state to a vapor phase. When used in combination with soil vapor

extraction (SVE), air bubbles carry vapor phase contaminants to a SVE system

which removes them. The SVE system controls vapor plume migration by

creating a negative pressure in the unsaturated zone through a series of extraction

wells. Using air sparging as an SVE enhancement technology increases

contaminant movement and enhances oxygenation in the subsurface which

increases the rate of contaminant extraction. Air sparging can employ horizontal

or vertical wells and is designed to operate at high flow rates. The target

contaminant groups for air sparging are volatile organic compounds (VOCs) and

fuels. Air sparging is generally more applicable to the lighter gasoline

constituents such as benzene, ethylbenzene, toluene, and xylene. It is less

applicable to heavier constituents such as diesel fuel and kerosene.

Air Sparging
5
6

TECHNOLOGY SUMMARY: BIOVENTING

Bioventing is an in situ remediation technology that uses microorganisms to

biodegrade organic constituents adsorbed on soils in the unsaturated zone.

Bioventing enhances the activity of indigenous bacteria and simulates the natural

in situ biodegradation of hydrocarbons in soil by inducing air or oxygen flow

into the unsaturated zone and, if necessary, by adding nutrients. During

bioventing, oxygen may be supplied through direct air injection into residual

contamination in soil. Bioventing primarily assists in the degradation of

adsorbed fuel residuals, but also assists in the degradation of volatile organic

compounds (VOCs) as vapors move slowly through biologically active soil.

Bioventing systems are typically operated at vapor extraction rates lower than

those used for soil vapor extraction (SVE) systems in an effort to provide only

enough oxygen to sustain microbial activity. Bioventing can be used to treat all

aerobically biodegradable constituents; however, it has proven to be particularly

effective in remediating releases of petroleum products including gasoline, jet

fuels, kerosene, and diesel fuel. Bioventing is most often used at sites with midweight petroleum products, such as diesel and jet fuel. Lighter products such as

gasoline tend to volatilize readily and can be removed more rapidly using SVE

and heavier products such as lubricating oils generally take longer to biodegrade,

making bioventing a less effective option.

Bioventing
7
8

TECHNOLOGY SUMMARY: FRACTURING

Pneumatic

Fracturing

Hydraulic

Fracturing

Pneumatic fracturing is an enhancement technology designed to increase the

efficiency of other in situ technologies in difficult soil conditions. Pneumatic

fracturing injects pressurized air beneath the surface to develop cracks in low

permeability and over-consolidated sediments to create additional subsurface air

flow. These new passageways increase the effectiveness of in situ processes,

including soil vapor extraction (SVE), and enhance extraction efficiencies by

increasing contact between contaminants adsorbed onto soil particles and the

extraction system. This technology is used primarily to fracture silts, clays, shale,

and bedrock. Pneumatic fracturing is applicable to a complete range of

contaminant groups with no particular target group.

Hydraulic fracturing is an enhancement technology designed to increase the

efficiency of other in situ technologies in difficult soil conditions. The process

involves injecting a fluid which contains sand, polymers, or other compounds to

maintain open fractures in the subsurface soils and increase soil permeability. The

hydraulic fracturing process is repeated at varying depths (typically 5 to 30 ft)

creating a “stack” of sand-filled fractures. This technology is used primarily to

fracture silts, clays, shale, and bedrock. Hydraulic fracturing is applicable to a

complete range of contaminant groups with no particular target group.
9
10

TECHNOLOGY SUMMARY: THERMAL ENHANCEMENTS

Hot air injection consists of delivering hot air into the subsurface via an injection

well to heat the contaminated zone in an effort to strip and recover subsurface

contaminants. Hot air injection increases the phase-change and diffusion rates of

organic contaminants, liberating them from the porous soil and enabling them to

be captured by a SVE system. Hot air injection is often used in conjunction with

steam heating to ensure that stripped organics remain in the gas stream. Hot air

injection can raise soil temperature; however, because of the low heat capacity

of gases, it has limited applications compared to other heating mechanisms.

Target contaminant groups for hot air injection include VOCs and semi-volatile

organic compounds (SVOCs).

In situ steam stripping involves: (1) delivering steam to the contaminated zone

via injection wells; (2) heating the contaminated zone to vaporize the

contaminants and increase their mobility; and (3) creating a pressure gradient to

control movement of the contaminants and the steam condensate front to a

recovery point. The use of steam stripping results in the flow of contaminant

liquids ahead of the steam condensation front. Vaporized components rise to the

vadose zone where they can be removed by SVE and treated. The target

contaminant groups for steam stripping are VOCs, SVOCs, and fuels.

Electrical resistance heating uses an electric current to heat less permeable soils

such as clays and fine-grained sediments so that water and contaminants trapped

in these relatively conductive regions are vaporized and ready for vacuum extraction. Electrodes are placed directly into the less permeable soil matrix and

activated so that an electrical current passes through the soil, creating a resistance

which then heats the soil. The heat dries out the soil causing it to fracture. These

fractures make the soil more permeable allowing the use of soil vapor extraction

(SVE) to remove the contaminants. The heat created by electrical resistance

heating also forces trapped liquids to vaporize and move to the steam zone for

removal by SVE. Target contaminant groups for electrical resistance heating

include volatile organic compounds (VOCs), semi-volatile organic compounds

(SVOCs), and VOC-oil mixtures.

Radio frequency heating is used to increase the mobility of contaminants so they

can be removed more easily. The process involves delivering energy to the

subsurface via radio-frequency waves which excite molecular motion and induce

heating (much in the same way a microwave oven heats food). Heating promotes

Hot Air

Injection

Steam

Injection

Electrical

Resistance

Heating

Radio

Frequency

Heating
11

the volatilization of a wider spectrum of soil contaminants and increases contaminant mobility, thereby

increasing extraction rates. After radio frequency heating, sub-surface conditions are excellent for

biodegradation of residual contaminants. Radio frequency heating has the potential to increase

subsurface temperatures well above the boiling point of water (100°C, 212°F), allowing for more rapid

removal of higher boiling point compounds than is possible with other heating mechanisms. Radio

frequency heating is used to extract volatile and semi-volatile organic compounds (VOCs and SVOCs)

as well as VOC-oil mixtures and other organic compounds that are difficult to remove with ambient

temperature vacuum extraction.
12
13

ABSTRACTS OF SOIL VAPOR EXTRACTION

ENHANCEMENT TECHNOLOGY RESOURCES

The abstracts below describe the contents of pertinent SVE enhancement technology documents. The abstracts are organized

alphabetically within each of the five following document types:

Begins on Page

• Guidance Documents ........................................................................................................................................... 13

• Overview/Program Documents ............................................................................................................................ 14

• Studies and Demonstrations: Test Design ........................................................................................................... 23

• Studies and Demonstrations: Study Results ........................................................................................................ 25

• Other Resource Guides......................................................................................................................................... 34

To quickly identify documents pertinent to your interest area, see the Soil Vapor Extraction Enhancement Technology

Resource Matrices in the section titled "Technology Summaries" on page 4-12 of this Guide. The documents in the matrices are organized alphabetically within the document types identified above. The document listings in the matrices can be

cross-referenced with the abstracts using the code to the left of the document titles on the matrices. In an effort to limit the

number of resources listed here, Records of Decision (RODs) and documents more than five years old are not included.

Those seeking RODs may wish to contact the hotlines, dockets, or other sources. These abstracts were obtained from several

databases, including NTIS, Energy Science and Technology, Compendex Plus, Enviroline, PTS Newsletter, PTS PROMT,

SciSearch, and CA Search.

GUIDANCE DOCUMENTS

13A

A Citizen’s Guide to Air Sparging, Fact Sheet.

U.S. Environmental Protection Agency, Office of Solid

Waste and Emergency Response, Technology Innovation

Office, March 1992.

 EPA Document Number: EPA/542/F-92/010

 NTIS Document Number: PB92-235597/XAB

The fact sheet contains a description of air sparging and how it

works, the reasons for using this treatment method, an explanation

of its performance reliability where air sparging is being used, and

a contact for obtaining more information on this treatment.

13B

A Citizen’s Guide to Bioventing, Technology Fact Sheet.

U.S. Environmental Protection Agency, Office of Solid

Waste and Emergency Response, Technology Innovation

Office, March 1992.

 EPA Document Number: EPA/542/F-92/008

This fact sheet provides a general overview of bioventing and

bioremediation. It includes a brief discussion of how bioventing

works in conjunction with soil vapor extraction and lists some

advantages of using bioventing as a remediation technology.

This document includes information on site conditions that are

most compatible with bioventing and provides examples of

sites where bioventing is being applied.

13C

Conceptual Design of Air Sparge/Soil Vent Systems for

In Situ Remediation of Petroleum Hydrocarbons,

PETRO-SAFE ’92 Conference Papers: Volume 7 (Processing and Refining 2), Volume 8 (Transportation and

Storage), Volume 9 (Spill Control, Disposal, and Remedial Treatment 1) and Volume 10 (Spill Control, Disposal, and Remedial Treatment 2), Conference Literature.

Clodfelter, C. L., PETRO-SAFE ’92: Third Annual Environmental and Safety Conference for the Oil, Gas, and Petrochemical Industries, Houston, TX, January 1992.

A conceptual design for a sparge and vent system is presented.

A sparge and vent system consists of air sparging or in situ

aeration in combination with soil vapor extraction. With air

sparging, a compressed air source provides sparging of the

groundwater through aeration points, volatizes dissolved hydrocarbons, and elevates dissolved oxygen (DO) levels in the

groundwater. Volatile hydrocarbon vapors migrate more readily

than liquid in soil, and are extracted to the atmosphere with the

vapor extraction system. Increased oxygen levels in the groundwater and unsaturated soil promotes natural, aerobic biodegradation of the hydrocarbons without nutrient addition. Design

considerations for sparge systems include spacing and depth of

installation of the sparging points, air injection rates and pressures, and the air source. The design techniques for the soil

vapor extraction system have been discussed extensively in the

literature, but generally involve spacing of the extraction wells

to capture all the hydrocarbons stripped from the groundwater.

The soil vapor extraction system can also be modified to

enhance oxygen (air) delivery to the unsaturated zone and thus

promote natural biodegradation of the petroleum hydrocarbons
14

14C

Test Plan and Technical Protocol for a Field Treatability

Test for Bioventing, 2nd Revision.

Downey, D. C.; Frand, R.; Hinchee, R. E.; Miller, R. N.; and

Ong, S. K., Battelle, U.S. Air Force Center for Environmental Excellence, Environmental Services Office, EngineeringSciences, Inc., May 1992.

This test plan and technical protocol describes methods for

conducting field treatability tests for bioventing technology. The

purpose of these field test methods is to measure the soil gas

permeability and microbial activity at a contaminated site and to

evaluate the potential application of the bioventing technology to

remediate the contaminated site. Bioventing is the process of

aerating subsurface soils to stimulate in situ biological activity.

This report includes an overview of bioventing, various applications of this technology, and discussions of specific sites including

Hill Air Force Base (AFB) and Tyndall AFB.

14D

Tiny Bubbles Pop to Deep Clean, Journal Article:

Published in Soils, October 1992.

Marley, M.; Hazebrouck, D.; and Walsh, M.

This article provides an overview of factors that should be

considered when designing, installing, and operating an in situ

air sparging system for remediating contaminants found in

saturated zone soils. The factors discussed include: bubble

geometry and gas channeling; contaminants most amenable to

air sparging (i.e., petroleum compounds and chlorinated solvents); gas (air) flow rate; gas (air) injection pressure; site

geometry considerations; site geology considerations; injection point interval (i.e., the sparging well screened interval and

the depth location of the screened interval with respect to the

static water table); radius of injection point influence; and air

sparging equipment. A brief discussion of the advantages and

disadvantages of air sparging is also included.

OVERVIEW/PROGRAM DOCUMENTS

14E

Air Sparging and Vapor Extraction as a Means of Removing Chlorinated and BTEX Compounds in Complex

Groundwater Conditions: Published in the Superfund XIV

Conference and Exhibition Conference Proceedings, Volume 1, Washington, D.C., November 30 - December 2, 1993.

Barrera, J.A., 1994.

This paper presents full scale air sparging and vapor extraction

applications in difficult and atypical conditions. Air sparging,

or enhanced groundwater aeration, is an innovative in situ

technique used to restore groundwater conditions. Site candiOverview/Program Documents

in the soil. Techniques for monitoring the progress of remediation

include: measurement of oxygen and carbon dioxide levels in

the soil; DO levels in the groundwater; subsurface air pressures;

and petroleum hydrocarbon levels in the discharged air, soil,

and groundwater.

14A

How to Evaluate Alternative Cleanup Technologies for

Underground Storage Tank Sites, A Guide for Corrective

Action Plan Reviewers.

U.S. Environmental Protection Agency, Office of Solid

Waste and Emergency Response, Office of Underground

Storage Tanks, October 1994.

 EPA Document Number: EPA/510/B-94/003

This manual provides detailed technical guidance for state

regulators who oversee cleanups and evaluate corrective actions plans (CAPs) for leaking underground storage tank sites.

The technologies addressed in the manual include soil vapor

extraction, bioventing, biopiles, landfarming, low-temperature

thermal desorption, air sparging, biosparging, and natural attenuation. The text focuses on engineering-related considerations for evaluating each technology; however, this manual

does not provide instruction on the design and construction of

remedial systems or guidance on regulatory issues. Examples

of issues evaluated for each technology include effectiveness,

site characteristics, constituent characteristics, pilot scale studies, system components, system design, and operation and

monitoring plans. References are provided for each technology.

14B

Remediation by In Situ Aeration: The Power of Volatilization and Bio-Oxidation, Journal Article: Published in

The National Environmental Journal, v3n4, July-August

1993.

Vance, D. B.

This article provides an overview of soil vapor extraction

(SVE), air sparging, bioventing, and biosparging. There is a

discussion of SVE and bioventing which includes information

on the circumstances under which each technology is optimally

effective and a comparison of hydrocarbon removal rates. In

addition, the effect of contaminant vapor pressure on SVE

remediation rates and the effect of indigenous bacteria on

biosparging viability are discussed. The article concludes with

a case study on the use of biosparging at a facility where a

RCRA hazardous waste drum storage area was being closed.

Soil contaminants at the site include ethlybenzene, toluene,

total xylenes, and naphthalene; groundwater contaminants

include ethylbenzene and total xylenes. Results of the case

study, including trends in VOC and CO2 content of recovered

soil gas, is provided.
15

dates are usually limited to permeable sediments impacted with

highly volatile aromatic and aliphatic compounds. Air sparging

involves stripping dissolved volatile organic compounds (VOCs)

in shallow or perched aquifers. Typical sparging systems

consist of pressurized air injection wells advanced into an

aquifer. Controlled air injection encourages aqueous phase

VOCs to mobilize upward into the unsaturated soil. Soil vapor

extraction (SVE) wells or trenches are employed to recover

VOCs transferred into the unsaturated soils. Vapor extraction

is typically used in combination with air sparging to recover

VOCs and to prevent vapor phase transport off-site.

15A

Air Sparging in Conjunction With Vapor Extraction for

Source Removal at VOC Spill Sites, Conference Literature.

Marley, M. C., Fifth National Outdoor Action Conference on

Aquifer Restoration, Groundwater Monitoring, and Geophysical Methods, Las Vegas, NV, May 1991.

Effective source removal is the singularly most important

activity in achieving remediation at a contaminated site. Vapor

extraction (soil venting) has been demonstrated to be a successful and cost effective remediation technology for removing

VOCs from vadose (unsaturated) zone soils. However, in many

cases, seasonal groundwater table (GWT) fluctuations, GWT

drawdown associated with pump and treat remediation techniques, and spills involving dense, non-aqueous phase liquids

(DNAPL) create residually saturated soils below the water

table. Vapor extraction alone is not considered to be an optimal

remediation technology to address these areas of contamination. Artificial water table drawdown is one approach that may

be utilized to expose the contaminated soils, thereby increasing

the efficiency of the soil venting process. However, in some

cases, this is not a practical, nor cost effective approach. An

alternative approach is the use of sparging (injection) wells to

inject a hydrocarbon free gaseous medium (standardly air) into

the saturated zone below the areas of contamination. The

contaminants are dissolved in the groundwater and sorbed on

the soil partition into the advective air phase effectively simulating an in situ air stripping system. The stripped contaminants

are transported in the air phase to the vadose zone, within the

radius of influence of the vapor extraction system. The contaminant vapors are drawn through the vadose zone to a vapor

extraction well where they are treated utilizing standard vapor

extraction off-gas control system(s).

15B

Air Sparging Technology Evaluation, Proceedings of

Research and Development ‘92, Conference Literature.

Loden, M. E. and Fan, L., Second National Research and

Development Conference on the Control of Hazardous

Materials, San Francisco, CA, Hazardous Materials Control

Resources Institute, February 1992.

Air sparging, which is also referred to as in situ air stripping and

in situ volatilization, involves the injection of air into the

saturated zone to strip VOCs dissolved in groundwater and

absorbed to soils from the saturated zone. The vapor phase

contaminants transferred to the unsaturated zone are then

captured using soil vapor extraction (SVE). In addition to

contaminant removal via mass transfer, the introduction of

oxygen by injection of air also enhances subsurface biodegradation of contaminants. The air sparging system design requires consideration of system component compatibility and

operation to ensure optimization of blower selection, well

configuration design, and air emissions treatment. The technology is applicable to gasoline, solvents, and other volatile

contaminants. Air sparging systems are almost always coupled

with soil vapor extraction to control the subsurface air flow.

Proper hydraulic control is key to preventing migration of

contaminants to uncontaminated areas. Air sparging is a

relatively new treatment technology. Research efforts to date

have not fully elucidated the scientific bases of the system, and

the associated engineering aspects are not completely defined.

However, a substantial amount of information is available

describing the effectiveness and characteristics of air sparging

systems. This paper summarizes the available literature and

case studies regarding the use of air sparging technology as it

has been implemented to date and identifies research needs.

15C

An Overview of In Situ Air Sparging, Journal Article:

Published in Ground Water Monitoring and Remediation,

v13n4, Fall 1993.

Johnson, R. L.; Johnson, P. C.; McWhorter, D. B.; Hinchee,

R. E.; and Goodman, I.

In situ air sparging (IAS) is becoming a widely used technology

for remediating sites contaminated by volatile organic materials such as petroleum hydrocarbons. Published data indicate

that the injection of air into subsurface water saturated areas

coupled with soil vapor extraction (SVE) can increase removal

rates in comparison to SVE alone for cases where hydrocarbons

are distributed within the water saturated zone. However, the

technology is still in its infancy and has not been subject to

adequate research, nor have adequate monitoring methods been

employed or even developed. Consequently, most IAS applications are designed, operated, and monitored based upon the

experience of the individual practitioner. The use of in situ air

sparging poses risks not generally associated with most practiced remedial technologies; air injection can enhance the

undesirable off-site migration of vapors and groundwater contamination plumes. Migration of previously immobile liquid

hydrocarbons can also be induced. Thus, there is an added

incentive to fully understand this technology prior to application. This overview of the current state of the practice of air

sparging is a review of available published literature, a consultation with practitioners, and a range of unpublished data

Overview/Program Documents
16

reports, as well as theoretical considerations. Potential strengths

and weaknesses of the technology are discussed and recommendations for future investigations are given.

16A

Application of Steam Injection/Vacuum Extraction

Treatment Systems to Contaminated Soils: Published in

Proceedings of Environmental Protection Agency/Air

and Waste Management Association, In Situ Treatment

of Contaminated Soil and Water, 1992.

de Percin, P. R., U.S. Environmental Protection Agency,

Cincinnati, OH, Risk Reduction Engineering Laboratory.

 EPA Document Number: EPA/600/A-93/274

 NTIS Document Number: PB94-122579/XAB

Steam Injection/Vacuum Extraction (SIVE) is a method to

enable vacuum extraction to treat soils contaminated with

semivolatile organic compounds (SVOCs) and to speed the

cleanup of soils contaminated with volatile organic compounds

(VOCs). The steam injection raises the soil temperature causing more VOCs and SVOCs to vaporize into the soil air spaces.

The vacuum extraction wells create a pressure drop in the soil

causing gas flow to the well and thus removing the vaporized

organics. This pressure drop maintains the concentration

gradient forcing the organics contaminants into the vapor phase

and allowing for further removal of the organics. After a

considerable amount of laboratory research, SIVE is now being

applied to field situations. One full-scale remediation has been

performed and several pilot-scale systems have been installed

and are now being studied. This paper discusses each of these

systems, the data that will be obtained, and the information that

still needs to be developed.

16B

Bioventing Remediates Hydrocarbon Contamination,

Journal Article: Published in The National Environmental Journal, v3n6, November-December 1993.

Morrow, S.

This article discusses the uses of bioventing to remediate soils

contaminated with organic contaminants, in particular fuel

hydrocarbons, and heavy organic contaminants such as No. 2

oil and diesel fuel. A brief discussion of ways to analyze the

effectiveness of boiventing is included, and advantages and

disadvantages of boiventing are presented. The article concludes with the results of a boiventing treatability study. The

study was conducted to determine the best treatment for

remediating a landfill contaminated with volatile chloroform

and semivolatile organic waste, including trichloroethylene,

phthalates, and highly organic sludge.

Overview/Program Documents

16C

Cleaning Up Underground Contaminants, Journal

Article: Published in Energy and Technology Review,

May 1994.

At hundreds of industrial and government sites across the

United States, environmental consulting firms are designing

permanent containment systems for underground contaminants

such as hydrocarbon fuels, cleaning solvents, and industrial

chemicals. In quantities of thousands of liters or more, these

chemicals threaten to contaminate drinking water supplies for

hundreds of years. Typical containment systems (e.g., deep

wells of cement or clay, or hydraulic pumping to control

groundwater movement) can keep the chemicals from further

contaminating groundwater if they are properly maintained for

many years, but they do not remove the contaminants. Clearly,

removing the contaminants from the soil is a much preferable

solution than containing them and attempting to prevent their

spread. A dynamic underground stripping process that combines steam and electrical heating of underground soils with

vacuum extraction of vapors and fluids and guiding these

processes by real-time monitoring methods is described.

16D

Comparison of the Effectiveness of Emerging In Situ

Technologies and Traditional Ex Situ Treatment of

Solvent-Contaminated Soils, Conference Literature.

Just, S. R. and Stockwell, K. J., ACS Symposium 518:

Emerging Technologies in Hazardous Waste

Management III, Atlanta, GA, October 1991.

Since the implementation of RCRA’s Land Disposal Restrictions (LDRs) in November 1990, solvent contaminated soils

must meet higher cleanup standards. This document looks at

various treatment technologies, both standard and innovative,

in light of the LDRs. The innovative soil vapor extraction

(SVE) enhancement technologies reviewed include radio frequency heating, stream stripping, and in-situ bioremediation.

The document describes each technology and discusses the

applicability and feasibility of each technology. In addition, it

analyzes test results from studies conducted to evaluate the

technologies. The test results include data on the cleanup levels

achieved at the study sites. Each technology review lists the

advantages and disadvantages of the technology and includes a

diagram of the technology. The conclusion of this document

presents a comparison of the removal efficiencies of all the

technologies discussed, including the non-innovative technologies.
17

Overview/Program Documents

17A

Dual Process Strips Contaminants in Soil, Journal

Article: Published in Environmental Protection, v4n11,

November 1993.

Dieter, D. K.

This article provides an overview of the steam injection and

vacuum extraction (SIVE) process, which uses injection wells

to introduce steam into the subsurface in conjunction with

extraction wells to remove both groundwater and vapors from

subsurface soils. The steam, as it flows from injection well to

extraction well, strips contaminants from subsurface soils. The

heat transferred to the subsurface increases the phase-change

and diffusion rates of volatile and semi volatile organic compounds (VOCs and SVOCs) thereby reducing the time required

for contaminant extraction. Included in the discussion are

advantages of using SIVE over other injection techniques,

benefits of using SIVE to remove chlorinated solvents, as well

as equipment needs for implementing this technology.

17B

Engineering Forum Issue: Considerations in Deciding to

Treat Contaminated Unsaturated Soils In Situ.

Smith, L. A., Battelle, Columbus, OH, U.S. Environmental

Protection Agency, Cincinnati, OH, Risk Reduction Engineering Laboratory, December 1993.

 EPA Document Number: EPA/540/S-94/500

 NTIS Document Number: PB94-177771/XAB

The purpose of the document is to provide assistance in deciding in situ treatment of contaminated soils as a potentially

feasible remedial alternative. Technical considerations that

affect the decision to treat soils in situ are discussed. General

factors which influence the selection of in situ treatment are

hydrogeologic flow regime, regulatory standards, time available for remediation, removal logistics, and waste conditions.

The document also provides information relevant to reviewing

and screening in situ technologies. Factors important to the

following in situ technologies are discussed: solidification/

stabilization, soil vapor extraction, bioremediation, bioventing,

vitrification, radio frequency heating, soil flushing, and steam

injection and extraction. Systems for delivery and recovery of

liquids, vapors, and energy to and from the subsurface are

included.

17C

Enhance Performance of Soil Vapor Extraction, Journal

Article: Published in Chemical Engineering Progress,

v89n6, June 1993.

Noonan, D. C.; Glynn, W. K.; and Miller, M. E.

Hydrocarbon recovery as a means of soil and groundwater

remediation has received considerable attention in the last few

years as the shortcomings of groundwater pump-and-treat

technologies have become more evident. A previous article

covered a wide range of in situ cleanup technologies and

provided guidance on how to choose among them. This article

examines soil vapor extraction (SVE) in more detail and explains how to improve the performance of SVE by combining

it with air sparging or steam injection. Air sparging injects air

below the groundwater surface to promote the volatilization of

volatile organic compounds (VOC) from the groundwater into

the vadose zone so that the VOCs can be removed via the SVE

system. Steam injection injects steam into the vadose zone to

increase the subsurface temperatures, thereby volatilizing organic compounds with high boiling points.

17D

Enhancing Vacuum Extraction of Volatile Organics

Using Electrical Heating, Conference Literature.

Buettner, H. M.; Daily, W.; and Ramirez, A., Lawrence

Livermore National Laboratory, CA, U.S. Department of

Energy, Washington, DC, September 1991.

 NTIS Document Number: DE93-015978/XAB

Vacuum extraction is an effective tool for the in situ removal of

liquid, residual, and vapor phase volatile hydrocarbons from

subsurface soils (Trowbridge, 1990). The vacuum extraction

process creates air flow through soils by decreasing the gas

phase pressure in the soil matrix. As the air flows through the

pore spaces, volatile organic compounds (VOCs) are volatilized and moved from the soil towards an extraction well. The

effectiveness of the process varies with the permeability of the

soil. For a given vacuum pressure applied to a well, higher air

flow rates will be observed in coarser-grained sediments which

have higher gas permeabilities, than fine-grained sediments.

Soils with lower gas permeabilities such as silts and clays,

require a stronger vacuum to induce air flow through the soil.

The capacity to induce air flow through fine-grained materials

reaches an upper limit when the required vacuum capacity

cannot be achieved. Remediation of fine-grained soils using

vacuum extraction may be ineffective because a closer spacing

between extraction wells will be required, or in fact may

become impossible for soils with very low permeabilities.

17E

Experimental Examination of Integrated Soil Vapor

Extraction Techniques, Journal Article: Published in

Proceedings of the Petroleum Hydrocarbons and Organic

Chemicals in Ground Water: Prevention, Detection, and

Restoration, Houston, TX, November 4-6, 1992.

Johnson, R. L.; Bagby, W.; Perrott, M.; and Chen, C. T.,

Oregon Graduate Institute of Science and Technology,
18

Overview/Program Documents

Beaverton Department of Environmental Science and

Engineering, U.S. Environmental Protection Agency,

Cincinnati, OH, Risk Reduction Engineering Laboratory.

 EPA Document Number: EPA/600/J-92/280

 NTIS Document Number: PB93-131738/XAB

Soil vapor extraction (SVE) has been shown to be effective at

removing hydrocarbons from the unsaturated zone. However,

at many spill sites significant fractions of the mass are at or

below the water table, in which case SVE is far less effective.

To improve its efficiency in cases where gasoline is trapped

below the water table, SVE can be used in conjunction with

other techniques to reach the trapped mass. In the last few years

the direct injection of air into the formation below the water

table (i.e., in situ sparging) has become a popular technique.

Another approach is to lower the water table to improve air flow

in the vicinity of the trapped product. This can be accomplished

either in the localized area of a groundwater drawdown cone or

as the result of larger scale dewatering. In experiments conducted at the Oregon Graduate Institute (OGI), hydrocarbon

spills into a large three-dimensional physical model filled with

sand are being used to study the efficiencies of SVE combined

with other techniques. Experiments to date have examined

SVE operating as a stand-alone technique, as well as in conjunction with air sparging below the water table, dewatering of

the ‘smear zone’ (i.e., where product is trapped as residual

below the water table), and air injection into the dewatered

smear zone.

18A

Fundamentals of Bioventing Applied to Fuel Contaminated Sites, Journal Article: Published in Environmental

Progress, v12n1, February 1993.

Dupont, R. R.

Bioventing entails the use of soil vapor extraction (SVE)

systems for the transport of oxygen to the subsurface, where

indigenous organisms are stimulated to aerobically metabolize

fuel components. Bioventing systems are designed and configured to optimize oxygen transfer and oxygen utilization efficiency, and are operated at much lower rates and with configurations much different than those of conventional SVE systems.

Bioventing system applications and design are contrasted to

those of conventional SVE systems, and the two key elements

of bioventing system design evaluation, i.e., in situ microbial

activity and air permeability determinations, are highlighted in

this paper. The application of bioventing to vadose zone

bioremediation was reviewed with particular emphasis on its

advantages over aqueous based bioremediation systems in

terms of its superior oxygen transfer efficiency. Finally, the

application of bioventing and bioventing design concepts are

illustrated through a case study of JP-4 jet fuel contaminated

soil remediation at Hill AFB, Utah.

18B

Give Soils a Breath of Fresh Air, Journal Article:

Published in Soils, November-December 1991.

Heuckeroth, R. W.

This article provides a brief overview of in situ remediation

technologies including pump and treat, soil washing, vapor

abatement, SVE, and SVE enhancement technologies. The

SVE enhancement technologies discussed include air sparging,

as it is used to remediate contaminated soil and ground water,

and bioventing, as it is used to remediate contaminated soil.

Each discussion includes a brief description of how the technology works as well as advantages and disadvantages of the

technology. The article concludes with a general discussion of

ex situ remediation technologies.

18C

Horizontal Wells Can Lower Costs of Remediating Soil,

Groundwater, Journal Article: Published in Oil and Gas

Journal, v91n48, November 1993.

Conventional approaches to soil and groundwater remediation

make extensive use of vertical wells that penetrate the various

contamination phases—liquid, absorbed, dissolved, and vapor.

But advances in horizontal drilling have added a new dimension

to the remediation of hazardous soils and groundwater. Whereas

conventionally drilled wells are perpendicular to the central

axis of hazardous waste, horizontal wells can travel parallel to

the axis. Dual wells can flank entire plumes for aggressive

treatment, and sparge points can become sparge barriers—

boundaries against migration of the contaminants. Under the

right conditions, a single horizontal well can treat areas that

previously required as many as 10 vertical wells. This not only

reduces drilling costs, but also eliminates redundant hardware

for groundwater pumping or soil vapor extraction. The paper

briefly describes five applications and discusses limitations to

the use of the technology.

18D

Horizontal Wells in Subsurface Remediation, Proceedings of HMC-South ’92 Exhibitor Conference and

Exhibition, Conference Literature.

Losonsky, G. and Beljin, M. S., HMC-South ’92: Hazardous

Materials Control Research Institute Meeting, New Orleans,

LA, February 1992.

This paper reports on horizontal wells which offer an effective

alternative to vertical wells in various environmental remediation

technologies. Hydrogeological advantages of horizontal wells

over vertical wells include a larger zone of influence, greater

screen length, higher specific capacity, and lower groundwater

screen entrance velocity. Because of these advantages, horizontal wells can reduce treatment time and costs of groundwa-
19

Overview/Program Documents

ter recovery (pump-and-treat), in situ groundwater aeration

(sparging), and soil gas extraction (vacuum extraction). Horizontal wells are also more effective than vertical wells in

landfill leachate collection (under-drains), bioremediation, and

horizontal grout injection.

19A

Hydraulic Fracturing to Improve Remediation of Contaminated Soil, Conference Literature.

Slack, W.W., OH; Kemper, M.; and Murdoch, L.C., University

of Cincinnati, May 1994.

EPA Document Number: EPA/540/R-94/503

This paper provides an overview of the applications of hydraulic fracturing to enhance the performance of in situ remediation

technologies, such as bioremediation and SVE. The paper also

includes a discussion of the benefits of hydraulic fracturing.

For example, hydraulic fractures can increase the area of

influence around an extraction well by a factor of ten, which

greatly enhances the ability of the extraction system to remove

contaminants. The paper indicates that low permeability silts,

clays, or rock are most favorable to hydraulic fracturing.

Descriptions of hydraulic fracturing technology demonstrations at field sites are included.

19B

In Situ Radio Frequency Heating to Enhance Vapor

Extraction of Contaminants from Soil, Journal Article:

Published in Industrial Health and Hazards Update,

v94n1, January 1995.

This report provides an overview of a radio frequency heating

field demonstration program. The demonstration site is contaminated with residual solvents, namely trichloroethylene and

perchoroethylene, which are held in vadose zone clay deposits.

The field demonstration is using radio frequency heating to

enhance the effectiveness of SVE in site remediation, by

increasing the contaminant vapor pressure, diffusivity, and the

permeability of the clay.

19C

Introducing USACE’s Soil Vapor Extraction and

Bioventing Engineer Manual: Published in Proceedings

of HMCRI Federal Environment Restoration IV and

Defense Cleanup Southeast Conference, Atlanta, Georgia,

March 14-15.

Baker, R.S., ENSR Consulting and Engineering, Acton, MA;

Becker, D.J., U.S. Army Corps of Engineers-Missouri River

Division, Omaha, NE, 1995.

This document provides a preview of the information that is

contained in an engineering manual (EM) prepared for the U.S.

Army Corps of Engineers (USACE) on the engineering and

design of SVE and bioventing systems. The EM assembles and

consolidates design considerations and guidance information

for practitioners of SVE and bioventing. This document discusses the purpose and intended audience of the EM and

provides a general overview of the topics addressed in the

manual. The topics include tools and resources; SVE and

bioventing application strategy; fundamental principles; site

characterization and technology screening; bench- and pilotscale testing for SVE and bioventing; design and full-scale

SVE and bioventing systems; design documents; start-up

requirements; operations and maintenance; system shutdown

and confirmation of cleanup; cost estimating and other considerations; and appendices.

19D

Livermore Dynamic Stripping Method Cleans Gasoline

Leaking Underground, Journal Article: Published in

Ground Water Monitor, v9n25, December 1993.

This article discusses using “dynamic” underground stripping,

a combination of steam and electric heating, with soil vapor

extraction (SVE) to remove gasoline from the soil. Results

from the first full-scale test conducted at the Lawrence Livermore

National Laboratory are evaluated. This article also discusses

the possibility of using “dynamic” underground stripping to

remove chlorinated solvents such as trichloroethylene and

perchloroethane.

19E

LNAPL Remediation by Soil Vapor Extraction and Air

Sparging, Journal Article: Published in Ground Water,

v32n5, September/October 1994.

Holt, W., Marion Environmental Inc., Chattanooga, TN,

September/October 1994.

The use of soil vapor extraction (SVE) in combination with in

situ air sparging (IAS) has the potential to be effective at quickly

removing volatile organic contamination from soils and ground

water in a cost effective manner. IAS is a process for treating

volatile organic contaminants in ground water and soil in the

saturated zone by the injection of air. The air displaces water in

the soil matrix, creating a transient porosity, and increases

dissolved oxygen levels in the ground water. The injected air

removes contaminants through volatilization and biodegradation. Innovative enhancement technologies such as IAS are

rapidly replacing more conventional excavation and

pump-and-treat remediation methods.
20

20A

Radio Frequency Heating Technology Enhances Soil

Vapor Extraction, Journal Article: Published in Hazardous Waste Consultant v12n4, July/August 1994.

This article discusses the benefits of using radio frequency

heating as an SVE enhancement technology, including its

ability to increase subsurface permeability, temperature, and

contaminant vapor pressure. The article includes a discussion

of two field tests which showed reduced levels of No. 2 fuel oil

and organchlorine pesticides when radio frequency heating was

applied.

20B

Recent Results from the SITE Program, Journal Article:

Published in Hazardous Waste Consultant, v12n1,

January-February 1994.

This paper presents results from the Superfund Innovative

Technology Evaluation (SITE) program testing of 12 innovative technologies. Two SVE enhancement technologies included in the paper are pneumatic fracturing and hydraulic

fracturing. Both pneumatic and hydraulic fracturing are used to

fracture rock and compacted soil which creates conductive

channels, thereby increasing contaminant extraction rates. The

discussion of each includes a process description, SITE demonstration results, and average costs. For the pneumatic fracturing

test, the primary contaminant of concern was trichloroethylene.

For the hydraulic fracturing test, the contaminants of concern

include ethylbenzene, benzene, toluene, xylene, a number of

chlorinated solvents, and petroleum hydrocarbons. Contact

names are provided.

20C

Refinements Upgrade Vapor Extraction: New Developments Enhance Use and Performance, Journal Article:

Published in Soils, March 1994.

This article provides a brief overview of three SVE refinements.

The first refinement is a turnkey SVE package that can be

customized to meet specific site needs. The second is a twophase SVE system which is a single treatment method applicable to all states of volatile hydrocarbon contamination. The

key to the two-phase system is that the well screening extends

below the natural water table and upwards into the vadose zone

which allows soil gases drawn into the well to entrain the liquid

phase so that both the gas and liquid phases are transported to

the surface. The third enhancement technology is a hot air

injection vapor extraction system which features a network of

hot air injection ducts placed within a soil matrix. The hot air

is able to volatilize and absorb the contaminants as it passes

through the soil to reach the vapor extraction ducts.

20D

REMEDIATION: Air Sparging Gains Acceptance for

Remediation of Underground Storage Tank Leaks,

Journal Article: Published in Waste Treatment Technology News, v8n4, February 1993.

EPA Region 5 has acknowledged BP Company for its role in

demonstrating the effectiveness of using air sparging technology, in combination with soil vapor extraction (SVE), to

remediate leaks from underground storage tanks. This method

is reported to reduce cleanup time at an average site by more

than one year over using SVE alone. This article provides an

overview of air sparging, as well as contact names and phone

numbers.

20E

Remediation of Contaminated Subsurface Soils by

Bioventing, Conference Literature.

Litherland, S. T.; Anderson, D. W.; Allen, P. G.; and Dykes,

R. S., Hazardous Materials Control/Superfund 92: 13th

Annual Conference and Exhibition, Hazardous Materials

Control Resources Institute, December 1992.

Soil venting or soil vapor extraction is a technology which has

in recent years been fairly widely accepted for the remediation

of soils contaminated with volatile organic compounds (VOC).

To affect VOC removal, a vacuum is applied to the vadose or

unsaturated zone to volatilize the residual organics and pull the

vapors to the surface for treatment. A relatively new adaptation

of soil vapor extraction is bioventing. Although the systems

used for soil venting and bioventing are very similar, the

approaches are slightly different. Soil vapor extraction (SVE)

primarily relies on the stripping of VOCs which then often

require treatment. SVE also is limited to volatile compounds.

A bioventing system promotes degradation of the organic

chemicals in the subsurface soil so that the required above

ground treatment of extracted vapors is minimized. Although

most of the work in bioventing completed to date has been with

jet fuels, the technology shows significant promise in the costeffective remediation of sites affected not only with fuels, but

also with some of the less volatile hydrocarbons.

20F

Remediation Technologies Screening Matrix and Reference Guide, Second Edition.

U.S. Department of Defense, Environmental Technology

Transfer Committee, Federal Remediation Technologies

Roundtable, October 1994.

EPA Document Number: EPA/542/B-94/013

NTIS Document Number: PB95-104782

Overview/Program Documents
21

Overview/Program Documents

of air injection below the water table and vacuum extraction in

the vadose zone, using a pair of horizontal wells. Our approach

is based on the construction of a site-specific numerical model

using the FEHM flow and transport code. We use the model as

a tool to investigate improvements to performance, to improve

the prediction of the performance of this technology over longer

periods of time and at different sites, and to compare performance with other remediation technologies.

21C

SVE, Air-Stripping Needed at Hastings Site, Journal

Article: Published in Superfund Week, v8n41, October

1994.

This article briefly discusses the proposed use of SVE and air

sparging to remediate contaminated groundwater at the Hastings

site in Hastings, Nebraska. An overview and cost estimate of

the work being conducted at various operable units is included.

Costs slated for the groundwater remediation effort are between

6 and 7 million dollars. The contaminants of concern at the site

are primarily chlorinated solvents and include trichloroethene,

1,1,1-trichloroethane, tetrachloroethene, and 1,1-

dichloroethene. The project is still in the design phase and

construction is scheduled to begin in February 1995. Contacts

names are provided.

21D

Technology Assessment of Soil Vapor Extraction and Air

Sparging.

Loden, M. E., Camp, Dresser and McKee, Inc., Cambridge,

MA, U.S. Environmental Protection Agency, Cincinnati,

OH, Risk Reduction Engineering Laboratory, September

1992.

 EPA Document Number: EPA/600/R-92/173

 NTIS Document Number: PB93-100154/XAB

Air sparging, also called ‘in situ air stripping’ and ‘in situ

volatilization’ injects air into the saturated zone to strip away

volatile organic compounds (VOCs) dissolved in groundwater

and absorbed into soil. These volatile contaminants transfer in

a vapor phase to the unsaturated zone where soil vapor extraction (SVE) can then capture and remove them. In addition to

removing VOCs via mass transfer, the oxygen in the injected air

enhances subsurface biodegradation of contaminants. Air

sparging is a relatively new treatment technology. Research

efforts have not yet fully elucidated the scientific basis (or

limitations) of the system, nor completely defined the associated engineering aspects. However, a substantial body of

available information describes the effectiveness and characteristics of air sparging systems. This document summarizes

the available literature and addresses case studies of practical

This guide can be used to screen and evaluate candidate cleanup

technologies for contaminated installations and waste sites.

The guide incorporates cost and performance data to the maximum extent possible and focuses primarily on demonstrated

technologies. The guide addresses contaminant properties and

behavior, and identifies potential treatment technologies based

on their applicability to specific contaminants and media. It

also provides an overview of each treatment process and how it

will impact technology implementation. The SVE enhancement technologies discussed in the guide include bioventing,

pneumatic fracturing, thermally enhanced SVE, high temperature thermal desorption, low temperature thermal desorption,

oxygen enhancement with air sparging, air sparging, hot water

or steam flushing/stripping, hydrofracturing, and air stripping.

Each technology profile, contained in this guide, includes a

description, applicability, limitations, data needs, performance

data, cost, site information, points of contact, and references.

The five contaminant groups highlighted are VOCs, SVOCs,

fuels, inorganics, and explosives.

21A

Scaling Up Vertical Soil Vapor Extraction Pilot Tests to

Horizontal Systems: Published in the Superfund XIV

Conference and Exhibition Conference Proceedings,

Volume 2, Washington, D.C., November 30 - December 2,

1993.

Bass, D.H., Groundwater Technology, Inc., Norwood, MA,

1994.

A design tool has been developed which estimates the vacuum/

flow performance of both horizontal and vertical SVE wells of

varying diameters, screened over various intervals, based on

pilot tests data from a single well. Equations describing the

relationship between these parameters are generated by modifying and adapting the standard transport equations for a buried

vertical sheet to represent vertical well, horizontal well, and

vented trench SVE systems respectively. This approach yields

reliable results so long as the screened intervals do not intercept

strata of significantly differing permeability. Two examples of

scaling up a vertical well SVE pilot test to a horizontal SVE

system are presented and discussed.

21B

Simulations of In Situ Air Stripping Demonstration at

Savannah River.

Robinson, B. A.; Rosenberg, N. D.; Zyvoloski, G.A.; and

Viswanathan, H., Los Alamos National Laboratory, NM,

U.S. Department of Energy, Washington, DC, June 1994.

 NTIS Document Number: DE94-013855/XAB

This report assesses the performance of the in situ air stripping

technology demonstrated at the Savannah River Integrated

Demonstration (SRID) site. This technology is a combination
22

Overview/Program Documents

of contamination. The contaminants dissolved in the groundwater and sorbed onto soil particles partition into the advective

air phase, effectively simulating an in situ air-stripping system.

The stripped contaminants are transported in the gas phase to

the treatment system. In situ air sparging is a complex multifluid phase process, which has been applied successfully in

Europe since the mid-1980s. To date, site-specific pilot tests

have been used to design air-sparging systems. Research is

currently underway to develop better engineering design methodologies for the process. Major design parameters to be

considered include contaminant type, gas injection pressures

and flow rates, site geology, bubble size, injection interval

(areal and vertical) and the equipment specifications. Correct

design and operation of this technology has been demonstrated

to achieve groundwater cleanup of VOC contamination to low

part-per-billion levels.

22C

The Application of Pneumatic Fracturing Extraction for

Removal of VOC Contamination in Low Permeable

Formations, Conference Literature.

Cicalese, M. E. and Mack, J. P., McLaren/Hart; Accutech

Remedial Systems; New Jersey Institute of Technology;

I&EC Special Symposium, American Chemical Society,

Atlanta, Georgia, September 27-29, 1993.

This document provides a description of pneumatic fracturing

at a site impacted by dense non-aqueous phase liquids (DNAPLs)

in clay and bedrock formations. Equipment specifications and

construction requirements are also highlighted with the use of

graphics. This paper also highlights plans for the Hillsborough

Superfund Innovative Technology Evaluation (SITE) demonstration comprised of the McLaren/Hart Environmental Engineering Corp., Accutech Remedial Systems Inc., the Hazardous

Substance Management Research Center (HSMRC), and the

New Jersey Institute of Technology team.

22D

Using Pneumatic Fracturing for In-Situ Remediation of

Contaminated Sites, Journal Article: Published in

Remediation, Spring 1995.

Schuring, J.R.; Chan, P.C.; and Boland, T.M., 1995.

This articles provides a general description of the concept of

pneumatic fracturing and a discussion of pneumatic fracturing

apparatus. Key technological considerations are also discussed, including fracture initiation, fracture orientation, fracture flow, and treatable contaminants and soils. The article

contains three case studies which describe different pneumatic

fracturing applications. The case studies include enhancement

of vapor extraction in clay; enhancement of vapor extraction in

bedrock; and enhancement of product recovery in stratified

deposits. The article concludes with a discussion of cost

benefits associated with pneumatic fracturing.

air sparging applications. It also identifies needs for further

research.

22A

Technology Evaluation Report: SITE Program Demonstration Test, Accutech Pneumatic Fracturing Extraction

and Hot Gas Injection, Phase 1, Volume 1.

Science Applications International Corp., Hackensack, NJ,

U.S. Environmental Protection Agency, Cincinnati, OH,

Risk Reduction Engineering Laboratory, July 1993.

 EPA Document Number: EPA/540/R-93/509

 NTIS Document Number: PB93-216596/XAB

The Pneumatic Fracturing Extraction (PFE) process developed

by Accutech Remedial Systems, Inc., makes it possible to use

vapor extraction to remove volatile organics at increased rates

from a broader range of vadose zones. The low permeability of

silts, clays, shales, etc., would otherwise make such formations

unsuitable for cost-effective vapor extraction and require more

costly approaches. Pneumatic fracturing provides an innovative means of increasing the permeability of a formation, thus

extending the radius of influence so contaminants can be

effectively extracted. In the PFE process, fracture wells are

drilled in the contaminated vadose zone and left open bore

(uncased) for most of their depth. A packer system is used to

isolate small (2 ft) intervals so that short bursts (- 20 sec) of

compressed air (less than 500 psig) can be injected into the

interval to fracture the formation. The process is repeated for

each interval. The fracturing extends and enlarges existing

fissures and/or introduces new fractures, primarily in the horizontal direction. When fracturing is complete, the formations

are then subjected to vapor extraction.

22B

The Application of In Situ Air Sparging as an Innovative

Soils and Groundwater Remediation Technology,

Journal Article: Published in Ground Water Monitoring

Review, v12n2, Spring 1992.

Marley, M. C.; Hazebrouck, D. J.; and Walsh, M. T.

Vapor extraction (soil venting) has been demonstrated to be a

successful and cost-effective remediation technology for removing VOCs from the vadose (unsaturated) zone. However,

in many cases, seasonal water table fluctuations, drawdown

associated with pump-and-treat remediation techniques, and

spills involving dense, non-aqueous phase liquids (DNAPL)

create contaminated soil below the water table. Vapor extraction alone is not considered to be an optimal remediation

technology to address this type of contamination. An innovative approach to saturated zone remediation is the use of

sparging (injection) wells to inject a hydrocarbon-free gaseous

medium (typically air) into the saturated zone below the areas
23

23A

VOCs in Non-Arid Soils Integrated Demonstration:

Technology Summary.

U.S. Department of Energy, Washington, DC, Office of

Technology Development, February 1994.

 NTIS Document Number: DE94-008863/XAB

The Volatile Organic Compounds (VOCs) in Non-Arid Soils

Integrated Demonstration (ID) was initiated in 1989. The

objectives for ID included testing the integrated demonstration

concept, demonstrating and evaluating innovative technologies/systems for the remediation of VOC contamination in soils

and groundwater, and transferring technologies and systems to

internal and external customers for use in full-scale remediation

programs. The demonstration brought together technologies

from DOE laboratories, other government agencies, and industry for demonstration at a single test bed. The Savannah River

Site was chosen as the location for this ID as the result of VOC

contamination of soil and groundwater. The primary contaminants, trichlorethylene and tetrachloroethylene, originated from

an underground process sewer line servicing a metal fabrication

facility at the M-Area. Some of the major technical accomplishments for ID included the successful demonstration of the

following: in situ air stripping coupled with horizontal wells to

remediate sites through air injection and vacuum extraction;

crosshole geophysical tomography to map moisture content

and lithologic properties of the contaminated media; in situ

radio frequency and ohmic heating to increase mobility of the

contaminants, thereby speeding recovery and the remedial

process; high-energy corona destruction of VOCs in the off-gas

of vapor recovery wells; application of a Brayton cycle heat

pump to regenerate carbon adsorption media used to trap VOCs

from the off-gas of recovery wells; in situ permeable flow

sensors and the colloidal borescope to determine groundwater

flow; chemical sensors to rapidly quantify chlorinated solvent

contamination in the subsurface; and in situ bioremediation

through methane/nutrient injection to enhance degradation of

contaminants by methanotrophic bacteria.

STUDIES AND DEMONSTRATIONS

TEST DESIGN

23B

Air Sparging and Groundwater Flow: Optimizing the

Remediation Potential of Air Sparging Through a

Horizontal Well, Journal Article: Published in Journal

of Environmental Health, v56n3, October 1993.

Wade, A.; Holland, B.; and Wallace, G., Association of

Groundwater Scientists and Engineers (AGWSE) Educational Seminar on Chlorinated Volatile Organic Compounds

In Groundwater.

Soil Vapor Extraction (SVE) systems are effective in volatilizing and extracting TCE from the soil in the vadose zone. When

used in combination with air sparging systems, SVE systems

can also be effective in volatilizing TCE from soil and groundwater in the saturated zone. At a site in the Midwest, several

plumes of TCE-contaminated groundwater, with concentrations ranging from several hundred to several thousand [mu]g/

1, have been identified in an unconfined sand and gravel aquifer

in which the groundwater flows at approximately 0.5 feet/day.

TCE concentrations of several thousand [mu]g/1 have been

detected in the vadose zone. A pilot study will be conducted of

a new design of air sparging at the site. A horizontal sparging

well and associated SVE system will be located perpendicular

to a plume down gradient from its source, but within the

associated area of vadose zone contamination. In addition, a

vertical air sparging well and SVE system will be located at the

source to accelerate volatilization of VOCs from the soil and

groundwater in the area of greatest contamination.

23C

Application of Microbial Biomass and Activity Measures

to Assess In Situ Bioremediation of Chlorinated Solvents,

International Symposium.

Phelps, T. J.; Herbes, S. E.; Palumbo, A. V.; Pfiffner, S. M.;

and Mackowski, R., Oak Ridge National Laboratory, TN,

U.S. Department of Energy, Washington, DC, 1993.

 NTIS Document Number: DE94-002489/XAB

Evaluating the effectiveness of chlorinated solvent remediation

in the subsurface can be a significant problem given uncertainties in estimating the total mass of contaminants present. If the

remediation technique is a biological activity, information on

the progress and success of the remediation may be gained by

monitoring changes in the mass and activities of microbial

populations. The in situ bioremediation demonstration at the

U.S. Department of Energy (DOE) Savannah River Site (SRS)

is designed to test the effectiveness of methane injection for the

stimulation of sediments. Past studies have shown the potential

for degradation by native microbial populations. The design

and implementation of the SRS Integrated Demonstration is

described in this volume. A control phase without treatment

was followed by a phase withdrawing air. The next phase

included vacuum extraction plus air injection into the lower

horizontal well located below the water table. The next period

included the injection of 1 percent methane in air followed by

injection of 4 percent methane in air. Literature hypothesizes

that the injection of methane would stimulate methanotrophic

populations and thus accelerate biological degradation of TCE.

Measuring the success of bioremediation is a complex effort

that includes monitoring changes in microbial populations

associated with TCE degradation. These monitoring efforts are

described in this paper and in related papers in this volume.

Studies and Demonstrations
24

24A

Electrovoice Site Demo Underway, Journal Article:

Published in Superfund Week, v7n45, November 19, 1993.

This brief article discusses a Superfund Innovative Technology

Evaluation (SITE) demonstration which is investigating the

effectiveness of air sparging and soil vapor extraction in

remediating soil and groundwater that are contaminated with

VOCs. The year-long demonstration project is taking place at

the Electrovoice Superfund site in Buchanan, Michigan. This

article includes contact names and phone numbers.

24B

EPA Selects Linemaster Cleanup, Journal Article:

Published in Superfund Week, v7n29, July 1993.

Soil vapor extraction (SVE), in conjunction with air stripping

and carbon adsorption, was selected as the remedy for removing

volatile organic compounds, including TCE, at the Linemaster

Switch Corporation Superfund site. This brief article describes

the site conditions and provides contact names and phone

numbers.

24C

Navy Hires Corps to Extract Hastings VOCs, Journal

Article: Published in Defense Cleanup, v5n15, April 15,

1994.

A pilot study using soil vapor extraction and air sparging to

remediate soil and groundwater at five sites in the Hastings East

Industrial Park is going to be conducted by the Kansas City

(Missouri) District of the Army Corps of Engineers. Contaminants at the five sites include trichloroethene, 1,1,1-

trichloroethane, and other volatiles found in the vadose zone.

This brief article includes contact names and phone numbers.

24D

Picillo SVE, UV/Oxidation Systems Eyed, Journal

Article: Published in Superfund Week, v7n26, July 1993.

Soil vapor extraction (SVE) using hot air injection as an

enhancement technology is a selected remedy for the Picillo Pig

Farm Superfund site in Rhode Island. Ground water, surface

water, soil, and sediments are contaminated with volatile and

semi-volatile organic compounds. The injected hot air would

volatilize the contaminants, while catalytic oxidation would

break down the volatile organics. In addition, ground water

would be pumped and treated using carbon adsorption and UV/

oxidation. Depending upon costs, ground water may be treated

by means of air stripping with carbon adsorption instead of hot

air injection. Contact names and phone numbers are provided.

24E

Pilot-Scale Evaluation of Groundwater Air Sparging:

Site-Specific Advantages and Limitations, Proceedings of

Research and Development ‘92, Conference Literature.

Martin, L. M.; Sarnelli, R. J.; and Walsh, M. T., Second

National Research and Development Conference on the

Control of Hazardous Materials, San Francisco, CA, Hazardous Materials Control Resources Institute, February 1992.

Vapor extraction (soil venting) has been demonstrated to be a

successful and cost-effective remediation technology for removing VOCs from vadose (unsaturated) zone soils. However,

in many cases, spills involving heavier than water solvents

create residually contaminated soils below the water table. The

use of air sparging wells to inject air into the saturated zone

below the areas of contamination in combination with vapor

extraction in the unsaturated zone is a possible approach to

remediating these saturated zone soils. The contaminants

dissolved in the groundwater and absorbed on the soil are

partitioned into the vapor phase by the introduction of pressured

air, which effectively simulates an in situ air stripping system.

Ideally, the stripped contaminants are transported in the vapor

phase to the vadose zone, within the radius of influence of the

vapor extraction system. A pilot-scale air sparging/vapor

extraction (AS/VE) system was installed at the site of a closed

manufacturing facility located in Connecticut to evaluate the

effectiveness of remediating saturated zone soils contaminated

with VOCs (mainly trichloroethene, TCE) which are impacting

groundwater quality. The system was operated continuously

for 4 weeks with air sparging at varying depths, flow rates, and

pressures, as well as continuous monitoring of total VOCs

removed in the vapor phase. Water levels, dissolved oxygen,

VOC levels and vapors were also monitored in 10 shallow wells

within the vicinity of the pilot study area before, during, and

after system operation.

24F

Sandia National Laboratories Mixed Waste Landfill

Integrated Demonstration, Conference Literature.

Tyler, L. D.; Phelan, J. M.; Prindle, N. K.; Purvis, S. T.; and

Stormont, J. C., Sandia National Laboratories, Albuquerque,

NM, U.S. Department of Energy, Washington, DC, 1992.

 NTIS Document Number: DE92-015005/XAB

The Mixed-Waste Landfill Integrated Demonstration (MWLID)

has been assigned to Sandia National Laboratories (SNL) by the

U.S. Department of Energy (DOE) Office of Technology

Development. The mission of the MWLID is to assess, implement, and transfer technologies and systems that lead to quicker,

safer, and more efficient remediation of buried chemical and

mixed-waste sites. The MWLID focus is on two landfills at

SNL in Albuquerque, New Mexico: the Chemical Waste

Studies and Demonstrations
25

Studies and Demonstrations

Landfill (CWL) and the Mixed-Waste Landfill (MWL). These

landfills received chemical, radioactive, and mixed wastes

from various SNL nuclear research programs. A characterization system has been designed for the definition of the extent

and concentration of contamination. This system includes

historical records, directional drilling, and emplacement membrane, sensors, geophysics, sampling strategy, and on site

sample analysis. In the remediation task, in situ remediation

systems are being designed to remove volatile organic compounds (VOCs) and heavy metals from soils. The VOC

remediation includes vacuum extraction with electrical and

radio-frequency heating. For heavy metal contamination, electrokinetic processes are being considered. The MWLID utilizes a phased, parallel approach. Initial testing is performed at

an uncontaminated site adjacent to the CWL. Once characterization is underway at the CWL, lessons learned can be directly

transferred to the more challenging problem of radioactive

waste in the MWL. The MWL characterization can proceed in

parallel with the remediation work at CWL. The technologies

and systems demonstrated in the MWLID are to be evaluated

based on their performance and cost in the real remediation

environment of the landfills.

25A

Scientists Test Mixed Waste Remedies at Sandia Landfills, Journal Article: Published in Ground Water Monitor, v8n20, October 1992.

Electrical and radio-frequency heating are being used with soil

vapor extraction (SVE) to remove VOCs from ground water at

two landfills at Sandia National Laboratories. In addition,

electrokinetic processes are being employed to remove heavy

metals. This brief article describes site conditions and provides

contact information.

25B

Textron Eyes SVE at its Cone Drive Plant, Journal

Article: Published in Superfund Week, v9n1, January

1995.

This article discusses Textron Inc.’s proposal to use SVE in

combination with air sparging to remediate the Cone Drive

Textron gear plant site in Travese City, MI. The soil at the site

is contaminated with perchloroethylene (PCE). The PCE has

impacted the groundwater plume which migrates off-site and

beneath an adjacent property. The site and contaminant migration path is described in detail. In addition to the PCE, oily, nonaqueous phase liquids (NAPLs) may be floating on the water

table, and xylene and naphthalene can be found in the ground.

The proposed SVE/air sparging system would be installed to

remediate the source area of the plume at the plant site. Contact

names are provided.

STUDIES AND DEMONSTRATIONS

STUDY RESULTS

25C

Accutech Pneumatic Fracturing Extraction and Hot Gas

Injection, Phase 1. Applications Analysis Report.

Skovronek, H. S., Science Applications International Corp.,

Hackensack, NJ, U.S. Environmental Protection Agency,

Washington, DC, Office of Emergency and Remedial

Response, March 1993.

 EPA Document Number: EPA/540/AR-93/509

 NTIS Document Number: PB94-117439/XAB

The report summarizes and analyzes the SITE demonstration of

Accutech’s Pneumatic Fracturing Extraction (PFE) process at

an industrial park in New Jersey. Based on the results of 4-hour

tests before and after fracturing, extracted air flow rate increased an average 600 percent and trichloroethene (TCE) mass

removal rate increased about 675 percent, primarily due to the

increased air flow. The radius for effective vapor extraction

also was enlarged by fracturing; extracted air flow rates increased 700 percent to 1,400 percent in wells at a 10 ft radius and

200 percent to 1,100 percent in wells 20 ft from the fracture

well. With passive air inlets, the extracted air flow rate

increased about 19,500 percent, and TCE mass removal rate

increased 2,300 percent. The estimated cost for full-scale

remediation of the site with PFE is $307/kg ($140/lb) of TCE

removed based on the SITE demonstration experience and

information provided by the developer. Major contributing

factors include: labor (29 percent); capital equipment (22

percent); and emissions collection/disposal (19 percent). Numerous assumptions are used in arriving at this cost. The results

of the two Hot Gas Injection (HGI) tests are inconclusive.

25D

A Full-Scale Bioventing Test to Remediate Fuel Hydrocarbons in Clay Soils at a Federal Installation, Conference Literature.

Makdisi, R. S.; Stanin, F. T.; Phelps, M. B.; and Downey, D.

C., Second Annual Federal Environmental Restoration

Conference and Exhibition, Washington, DC, May 1993.

A long-term leak from a No. 2 diesel fuel tank resulted in the

contamination of approximately 10,000 cubic yards of soil

beneath, and adjacent to, an office building on a U.S. Air Force

installation. Soils had been contaminated to a depth of over 40

feet, with fuel residuals ranging from approximately 500 to

2,000 mg total petroleum hydrocarbon (TPH)/kg. The primary

regulatory concern at this site is the potential for groundwater

contamination from alkylbenzenes and polyaromatic hydrocarbons. An in situ bioventing technique that removes fuel
26

residuals through the introduction of oxygen (via air) to the

subsurface to promote microbial fuel degradation was selected

for full-scale testing on the site. A primary vapor extraction

well (VEW-1) was constructed near the center of the spill site

in the backfill material and connected to a 50 scfm vacuum

system. A secondary vapor extraction well (VEW-2) was

installed in the undisturbed soils to estimate soil gas permeability. Nine multi-depth vapor monitoring points (VMPs) were

used to analyze soil gas permeability, radius and influence,

oxygen enhancement, and the biological respiration of fuel

hydrocarbons. Three primary tests were conducted. The first

test measured the vacuum influence at varying depths and

distances from the central extraction well. The results clearly

demonstrated the ability of this low-rate vacuum to stimulate

soil vapor flow at the 35 to 40 foot depth and up to 100 feet

laterally from the central extraction well.

26A

An Integrated Approach to the Remediation of a UST

Leak: Pilot-Scale Studies at Cameron Station, Research

Article: Published in Federal Facilities Environmental

Journal, v5n1, Spring 1994.

Shepard, L. T.; Martino, L. E.; Reed, L. L.; Dziewulski, D.

M.; Joss, C. J.; and Sydelko, T. G.

This articles discusses the process Argonne National Laboratory (ANL) used in a pilot-scale remediation study to determine

the effectiveness of an innovative SVE technology at remediating

an underground gasoline spill at the Cameron Station Military

Reservation in Alexandria, Virginia. The innovative SVE

technology consists of an internal-combustion engine which is

used to volatilize the contaminants in-situ, extract them, and

burn any hazardous vapors. As part of this study, ANL

investigated the applicability of indigenous bacteria for in-situ

bioremediation and the usefulness of bioventing for remediating

residual, heavier gasoline fractions left after SVE remediation

of the lighter gasoline fractions. The study determined that as

a result of the geohydrologic conditions at the site and the

associated problems with using horizontal wells for SVE, it was

inappropriate to design a system using horizontal wells at the

site. Instead, the option of using a dual vacuum extraction

system with vertical wells to extract and treat soil gas and

groundwater was suggested. Such a system would also enhance

the in-situ biodegradation of the gasoline present in the subsurface by bioventing.

26B

Bioventing—An Emerging Remediation Technology,

Conference Literature.

Ross, D. and Sudano, P., Proceedings of the 25th MidAtlantic Industrial Waste Conference, Bucknell University;

University of Cincinnati; University of Delaware; Drexel

University; Howard University; et al, Hazardous and

Industrial Wastes, 1993.

Studies and Demonstrations

This paper provides a description of bioventing and discusses

how the effects of bioventing can be measured by monitoring

soil oxygen concentrations, soil carbon dioxide concentrations,

and microbial activity in soil. This paper includes two bioventing

case studies. The first case study evaluates the potential use of

bioventing to remediate unsaturated waste and soil layers

contaminated with VOCs and SVOCs (including PAHs). Parameters evaluated in this study include microbial activity,

oxygen concentration, carbon dioxide concentration, VOCs

and SVOCs. Results of the first case study indicate that

bioventing is a viable remediation alternative for the site. The

second case study discusses the use of bioventing in combination with soil vapor extraction (SVE) to remediate VOC contaminated soil and groundwater at an active industrial manufacturing facility. This case study includes a brief description of

the SVE/bioventing system used at the manufacturing facility

and a discussion of the results of the study. Parameters such as

oxygen and carbon dioxide soil concentrations indicate that the

SVE/bioventing system has been effective at the site.

26C

Bioventing—A New Twist on Soil Vapor Remediation of

the Vadose Zone and Shallow Groundwater, Conference

Literature.

Yancheski, T. B. and McFarland, M. A., Sixth National

Outdoor Action Conference on Aquifer Restoration, Groundwater Monitoring and Geophysical Methods, Las Vegas,

NV, May 1992.

Bioventing, which is a combination of soil vapor remediation

and bioremediation techniques, may be an innovative, costeffective, and efficient remedial technology for addressing

petroleum contamination in the vadose zone and shallow groundwater. The objective of bioventing is to mobilize petroleum

compounds from the soil and groundwater into soil vapor using

soil vapor extraction and injection technology, and to promote

the migration of the soil vapor upward to the turf root zone for

degradation by active near-surface microbiological activity.

Promoting and maintaining optimum microbiological activity

in the turf root rhizosphere is a key component to the bioventing

technique. Preliminary ongoing U.S. Environmental Protection Agency bioventing pilot studies (Kampbell, 1991) have

indicated that this technique is a promising remediation technology, although feasibility studies are not yet complete. However, based on the preliminary data, it appears that proper

bioventing design and implementation will result in substantial

reductions of petroleum compounds in the capillary zone and

shallow groundwater, complete degradation of petroleum compounds in the turf root zone, and no surface emissions. A

bioventing system was installed at a site in southern Delaware

with multiple leaking underground storage tanks in early 1992

to remediate vadose zone and shallow groundwater contaminated by petroleum compounds. The system consists of a series

of soil vapor extraction and soil vapor/atmospheric air injection

points placed in various contamination areas and a central core
27

A site characterization of leaking underground gasoline and

diesel storage tanks at the University of Idaho, West Farm

Operations Center, identified approximately 800 cubic yards of

petroleum-contaminated soil exceeding regulatory action limits of 100 ppm TPH. Bioventing, a combination of in situ soil

vapor extraction and microbial degradation, was selected as a

remedial alternative on the basis of the presumably unsaturated

paleo-soil with a 45-foot depth to groundwater, and a microbial

study which concluded that indigenous petroleum-degrading

microorganisms existed throughout the contamination. Soil

vapor extraction tests were conducted by applying a 60-inch

water column vacuum to a soil vapor extraction well and

monitoring pneumatic pressure drawdown in 12 adjacent pneumatic piezometers and vertically distributed piezometer clusters. Pressure drawdown versus time data plots indicated that

air permeability was inadequate everywhere at the site except at

20 feet below ground surface. Low soil permeability created

conditions for a perched water table that was documented

during the investigation, resulting in unsatisfactory conditions

for in situ bioventing.

27C

Bioventing Petroleum Contaminated Soils, Proceedings

of Emerging Technologies for Hazardous Waste Management, Conference Literature.

Vogel, C. M. and Tedder, D. W., American Chemical

Society (ACS) Special Symposium on Emerging Technologies in Hazardous Waste Management, Atlanta, GA,

September 1992.

Soil vapor extraction (SVE) is a cost effective method for

removing volatile hydrocarbons from unsaturated soils. This

process also provides oxygen to the subsurface which enhances

the biodegradation of the volatile and nonvolatile hydrocarbon

contaminants. Bioventing technology combines the oxygen

delivery capabilities of SVE with nutrient and moisture management to maximize the amount of hydrocarbon removal by

biodegradation and minimize the amount of removal attributed

to volatilization. There is a growing list of bioventing field

demonstrations designed to remove a wide range of petroleum

hydrocarbons from the vadose zone. In this paper bioventing

field data is presented from a pilot-scale study at Tyndal AFB

FL, a full-scale cleanup effort at Hill AFB UT, and a feasibility

study in cold weather environment.

27D

Bioventing with Soil Warming in Alaska, Conference

Literature.

Sayles, G. D.; Brenner, R. C.; Hinchee, R. E.; and Vogel, C.

M., 86th Annual Meeting and Exhibition of the Air and

Waste Management Association (AWMA), Denver, CO, Air

and Waste Management Association, June 1993.

Studies and Demonstrations

remediation area (a large grassy plot). This system was chosen

for this site because it was least costly to implement and operate

as compared to other remedial alternatives (soil vapor extraction with carbon or catalytic oxidation of off-gas treatment, in

situ bioremediation, etc.), and results in the generation of no

additional wastes.

27A

Bioventing: A Successful Soil Vapor Remediation

Technique for the Vadose Zone and Shallow Groundwater, Conference Literature.

Yancheski, T. B. and McFarland, M. A., Hazardous Materials Control/Superfund 92: 13th Annual Conference and

Exhibition, Hazardous Materials Control Resources Institute,

December 1992.

Bioventing, a combination of soil vapor remediation and

bioremediation techniques, is an innovative, cost-effective, and

efficient remedial technology for addressing petroleum contamination in the vadose zone and shallow groundwater. The

objective of bioventing is to transfer petroleum compounds

from the soil and groundwater into soil vapor using soil vapor

extraction and injection technology and to promote the migration of the soil vapor upward to the turf root zone for degradation by active near-surface microbiological activity. Promoting

and maintaining optimum microbiological activity in the turf

root rhizosphere is a key component of the bioventing technique. A bioventing system was installed at a site in southern

Delaware with multiple leaking underground tanks during the

Summer of 1992 to remediate the vadose zone and shallow

groundwater contaminated by petroleum compounds. The

system, a combination of soil vapor extraction and injection

points, has very successfully reduced concentrations of petroleum compounds in the soil and has reduced the amount of free

product and petroleum concentrations in the shallow groundwater to the extent that nearby residential wells are no longer

threatened. Soil and groundwater cleanup goals for the site are

expected to be reached within 1 to 2 years of operation. Total

remediation costs to date have been less than $35,000. The

bioventing system is a promising low cost and effective alternative for the cleanup of petroleum related soil and groundwater contamination and has application at hundreds of similar

sites where there is little money available for remediation.

27B

Bioventing Feasibility Study of Low Permeability Soils

for Remediation of Petroleum Contamination, Conference Literature.

Brackney, K.M., Idaho State Government, Boise, ID, March

1994.

 NTIS Document Number: DE94-014144/XAB
28

gallons of gasoline from the site. This document includes a

DUS technology description and performance report as well as

discussions of technology applicability and alternatives, cost,

regulatory/policy requirements and issues, and lessons learned.

Appendices providing detailed information on demonstration

site characteristics, technologies, performance,

commercialization/intellectual property, and cost are also

included.

28B

Electrical Soil Cleaning Process, Journal Article: Published in Water Environment & Technology, v5n1,

January 1993.

A new technology that uses electricity to clean gasoline and

other solvents from soil and groundwater has been tested

successfully at Lawrence Livermore National Laboratory’s

Site, an experimental test facility near Tracy, California. Cleanup

of soil and groundwater contaminants is enhanced by heating

the soil electrically. In this process, electric currents flow

through the soil, heating it up in much the same way as the

heating element in a common household electric heater. When

combined with a system for extracting vapors from the soil, the

method shows promise for speeding up the cleanup process.

The small-scale test conducted recently at the site is the first

demonstration of the technology at a contaminated site. The

test showed that the vacuum-induced extraction removal rate of

the common solvent trichloroethylene from soil was more than

doubled by the addition of electrical heating. A large-scale test

was planned for late 1992 when electrical heating and vapor

extraction were to be combined with steam injection for cleaning a gasoline spill from the soil and groundwater at the

laboratory’s main site in Livermore, California.

28C

Feasibility of Hydraulic Fracturing of Soil to Improve

Remedial Actions.

Murdoch, L. C.; Losonsky, G.; Cluxton, P.; Patterson, B.;

and Klich, I., Cincinnati University, OH, U.S. Environmental

Protection Agency, Cincinnati, OH, Risk Reduction Engineering Laboratory, April 1991.

 EPA Document Number: EPA/600/2-91/012

 NTIS Document Number: PB91-181818/XAB

Hydraulic fracturing, a method of increasing fluid flow within

the subsurface, should improve the effectiveness of several

remedial techniques, including pump and treat, vapor extraction, bio-remediation, and soil-flushing. The technique is

widely used to increase the yields of oil wells, but is untested

under conditions typical of contaminated sites. The project

consisted of laboratory experiments, where hydraulic fractures

were created in a triaxial pressure cell, and two field tests, where

Studies and Demonstrations

Bioventing supplies oxygen in situ to oxygen deprived soil

microbes by forcing air through unsaturated contaminated soil

at low flowrates. Unlike soil venting or soil vacuum extraction

technologies, bioventing attempts to stimulate biodegradative

activity while minimizing stripping of volatile organics, thereby

destroying the toxic compounds in the ground. The U.S. EPA

Risk Reduction Engineering Laboratory began a 3-year field

study of in situ bioventing in the Summer of 1991 in collaboration with the U.S. Air Force at Eielson Air Force Base (AFB)

near Fairbanks, Alaska. The site has JP-4 jet fuel contaminated

unsaturated soil where a spill has occurred in association with

a fuel distribution network. The contractor operating the

project is Battelle Laboratories, Columbus, OH. At Eielson

AFB, bioventing is being studied in shallow soils in a cold

climate in conjunction with soil warming methods to enhance

the average biodegradation rate during the year. Roughly 1 acre

of soil is contaminated with JP-4 from a depth of roughly 2 feet

to the water table at 6 to 7 feet. The test area was established by

laying down a relatively uniform distribution of air injection/

withdrawal wells and constructing four 50 foot square test plots

within the test area. Thus, the test plots should receive relatively

uniform aeration. One plot is a control, i.e., bioventing only

with no heating. Three plots are being used to evaluate the

following three strategies of combining bioventing with warming of the soil above ambient temperature to increase the rate of

biodegradation year-round: (i) passive solar warming; (ii)

application of warm water; and (iii) buried heat tape. The

presentation will summarize the results for the first one and one

half years of operation including in situ biodegradation rates

due to bioventing as a function of season and soil warming

method, and an evaluation of the success of the various soil

warming methods at maintaining elevated soil temperatures.

28A

Dynamic Underground Stripping Demonstrated at

Lawrence Livermore National Laboratory Gasoline Spill

Site, Livermore, California: Published in Remediation

Case Studies: Groundwater Treatment.

Member Agencies of the Federal Remediation Technologies

Roundtable, March 1995.

 EPA Document Number: EPA/542/R-95/003

This document provides comprehensive information on the use

of Dynamic Underground Stripping (DUS) to remediate the

Lawrence Livermore National Laboratory (LLNL) site in

Livermore, California. DUS is a combination of three

technologies: steam injection, electric heating, and underground

imaging. Between 1952 and 1979, up to 17,000 gallons of

leaded gasoline were released from underground storage tanks

beneath a gasoline filling station at the 800-acre site. Soil and

groundwater were found to be contaminated with BTEX

(benzene, toluene, ethylbenzene, and xylene) and fuel

hydrocarbons. A commercial-scale field demonstration of

DUS, completed between 1992 and 1993, removed 7,600
29

Studies and Demonstrations

The FIVE system removed 1,270 kilograms of targeted contaminants and more than 49,000 kilograms of VOCs during two

months of operation.

29C

Hydraulic Fracturing Technology: Applications Analysis

and Technology Evaluation Report.

U.S. Environmental Protection Agency, Risk Reduction

Engineering Laboratory, Cincinnati, OH, September 1993.

 EPA Document Number: EPA/540/R-93/505

This paper discusses the hydraulic fracturing process and

illustrates its technical capabilities and specific contaminants

(e.g., ethylbenzene and organic compounds) remedied as it is

applied in conjunction with soil vapor extraction and

bioremediation. It also presents test findings (e.g., vapor yields

and contaminant recovery) from two sites, including performance enhancements, costs, and time durations.

29D

Hydraulic Fracturing to Improve In Situ Remediation of

Contaminated Soil, Concerence Literature.

Murdoch, L.C.; Kemper, M.; and Wolf, A., 1992 Annual

Meeting of the Geological Society of America (GSA),

Cincinnati, OH.

Hydraulic fracturing, a method that is widely used to increase

the production of oil wells at great depth in rock, is currently

being evaluated to increase the yield of environmental wells at

shallow depths in soil. In some tight formations, the method

promises to improve the effectiveness of in situ remediation,

whereas elsewhere it should allow in situ techniques, such as

vapor extraction or bioremediation, to be used where they

otherwise would be economically infeasible. The authors have

tested the method of creating hydraulic fractures in soil at six

sites underlain by over consolidated, silty-clay glacial drifeet.

In most cases, the fractures are gently dipping features that grow

away from the borehole and climb toward the ground surface.

Fractures 20 to 35 feet in maximum dimension are readily

created at depths of 5 to 15 feet. They are filled with between

5 feet [sup 3] and 12 feet [sup 3] of well-sorted, coarse-grained

sand, which provides an average thickness of 0.2 to 0.4 inches.

Hydraulic fractures can be created one on top of another,

stacked with depth at vertical spacing of 0.5 to 1 foot. Preliminary field tests lasting 40 days in uncontaminated ground at the

Center Hill Research Facility in Cincinnati, Ohio show that

hydraulic fractures increase the yield and the area affected by a

well during vapor extraction. Flow rates to a well intersecting

two hydraulic fractures were roughly 10 times greater than an

identical well that lacked hydraulic fractures. A pressure head

of [minus] 1 inch of water was measured 25 feet from the

fractured well, whereas similar pressure head was measured

only 2.5 to 3.0 feet from the conventional well. Field demonfractures were created at shallow depths in soil. The laboratory

tests show that hydraulic fractures are readily created in clayey

silt, even when it is saturated and loosely-consolidated. Many

of the laboratory observations can be explained using parameters and analyses based on linear elastic fracture mechanics.

Following the field tests, the vicinity of the boreholes was

excavated to reveal details of the hydraulic fractures. Maximum lengths of the fractures, as measured from the borehold to

the leading edge, averaged 4.0 m, with the average area being

19 sq m. Maximum thickness of sand ranged from 2 to 20 mm,

averaging 11 mm. As many as four fractures were created from

a single borehold, stacked one over the other at vertical spacing

of 15 to 30 cm.

29A

Final Report: In Situ Radio Frequency Heating Demonstration, Progress Report.

Jarosch, T. R.; Beleski, R. J.; and Faust, D., Westinghouse

Savannah River Co., Aiken, SC, U.S. Department of Energy,

Washington, DC, January 1994.

 NTIS Document Number: DE94-008274/XAB

A field demonstration of in situ radio frequency heating was

performed at the Savannah River Site (SRS) as part of the U.S.

Department of Energy-Office of Technology Development’s

Integrated Demonstration. The objective of the demonstration

was to investigate the effectiveness of in situ radio frequency

(RF) heating as an enhancement to vacuum extraction of

residual solvents (primarily trichloroethylene and perchloroethylene) held in vadose zone clay deposits. Conventional soil

vacuum extraction techniques are mass transfer limited because

of the low permeabilities of the clays. By selectively heating the

clays to temperatures at or above 100 degrees Celsius, the

release or transport of the solvent vapors is enhanced as a result

of several factors including an increase in the contaminant

vapor pressure and diffusivity and an increase in the effective

permeability of the formation with the release of water vapor.

29B

Fluid Injection Helps Vacuum Extract Contaminants,

Journal Article: Published in Soils, March 1994.

Cox, R. E.

This paper discusses the use of fluid injection as an SVE

enhancement technology at the Sand Creek Superfund site in

Denver, Colorado. The conditions of the Sand Creek site are

described and the performance of the fluid injection and vacuum

extraction (FIVE) process are discussed. Contaminants of

concern at the site were found in both the soil and ground water

and included petroleum hydrocarbons and chlorinated compounds such as tetrochloroethylene, trichloroethylene, chloroform, and methylene chloride. Of the targeted contaminants,

only tetrochloroethylene was detected in significant quantities.
30

Studies and Demonstrations

strations funded by the U.S. Environmental Protection Agency

are currently underway at two vapor extraction sites in Chicago,

Illinois and a bioremediation site in Dayton, Ohio. Other field

demonstrations at contaminated sites are planned for the near

future.

30A

In Situ Air Stripping of Contaminated Groundwater at

U.S. Department of Energy, Savannah River Site - Aiken,

South Carolina: Published in Remediation Case Studies:

Groundwater Treatment.

Member Agencies of the Federal Remediation Technologies

Roundtable, March 1995.

EPA Document Number: EPA/542/R-95/003

The document provides comprehensive information on the use

of in situ air stripping to remediate contaminated groundwater

at the U.S. Department of Energy (DOE) Savannah River site

in Aiken, South Carolina. An estimated 3.5 million pounds of

solvents were discharged from aluminum forming and metal

finishing operations performed at the site between 1958 and

1985, with over 2 million pounds sent to an unlined settling

basin. A pump and treat program has been ongoing since 1985

for removal of VOCs from the groundwater and a field

demonstration using in situ air stripping was conducted from

1990 to 1993. The demonstration was part of a program at

Savannah River to investigate the use of several technologies to

enhance the pump and treat system. The in situ air stripping

process increased VOC removal over conventional vacuum

extraction from 109 pounds per day to 129 pounds per day. This

document includes a technology description and performance

report, as well as discussions of technology applicability and

alternatives, cost, regulatory/policy requirements and issues,

lessons learned, and references. Appendices providing more

detailed information on demonstration site characteristics,

technology descriptions, performance, and commercialization/

intellectual property are also included.

30B

In Situ Remediation Technology Status Report:

Hydraulic and Pneumatic Fracturing.

U.S. Environmental Protection Agency, Office of Solid

Waste and Emergency Response, Technology Innovation

Office, April 1995.

EPA Document Number: EPA/542/K-94/005

This document describes the research and development of

hydraulic and pneumatic fracturing technologies to remove

contaminants from the soil and groundwater at waste disposal

and spill sites. Included are summaries of ten hydraulic and

pneumatic fracturing technology demonstrations. Each

technology demonstration summary contains a description of

the demonstration, the wastes treated, the current status,

demonstration results, contacts, and references.

30C

In Situ Remediation Technology Status Report: Thermal

Enhancements.

U.S. Environmental Protection Agency, Office of Solid

Waste and Emergency Response, Technology Innovation

Office, April 1995.

EPA Document Number: EPA/542/K-94/009

This document describes the development and application of

in situ thermal enhancement as a technology to remove

contaminants from soils and ground water at waste disposal

and spill sites. Included are summaries of ongoing or future

demonstrations and commercial applications, completed

demonstrations, and current research. Each summary

includes a description of the demonstration, the wastes

treated, the demonstration results or site status, contacts, and

references.

30D

New Pollutant Extraction Technique Results Termed

Excellent, Journal Article: Published in Report on

Defense Plant Wastes, v4n19, September 11, 1992.

The results of a demonstration which used pneumatic fracturing

in combination with soil vapor extraction (SVE) to extract

contaminants from low-permeability geologic formations are

discussed. The results are promising and indicate that air flow

was increased 80 times when pneumatic fracturing was used

with SVE as opposed to when SVE was used alone. The

primary contaminant at the study site was trichloroethylene

(TCE); however, the article discusses the potential application

of pneumatic fracturing for remediating sites with contaminants such as perchloroethylene and polynuclear aromatic

hydrocarbons (PAHs).

30E

New Soil Cleanup Technology, Journal Article: Published in New Jersey Industry Environmental Alert, v3n12,

September 1992.

Pneumatic fracturing, catalytic oxidation, and hot air injection

technologies were used, in conjunction with soil vapor extraction (SVE), to remove VOCs from soil and bedrock at the

Somerville site. This article enumerates the advantages of

using these enhancement technologies with SVE. Contact

names are provided.
31

31A

Passive Remediation of Chlorinated Volatile Organic

Compounds Using Barometric Pumping.

Rossabi, J.; Looney, B. B.; Dilek, C. A. E.; Riha, B.; and

Rohay, V. J., Westinghouse Savannah River Co., Aiken, SC,

U.S. Department of Energy, Washington, DC, 1993.

 NTIS Document Number: DE94-006387/XAB

The purpose of the Savannah River Integrated Demonstration

Program, sponsored by the U.S. Department of Energy, is to

demonstrate new subsurface characterization, monitoring, and

remediation technologies. The interbedded clay and sand

layers at the Integrated Demonstration Site (IDS) are contaminated with chlorinated volatile organic compounds (CVOCs).

Characterization studies show that the bulk of the contamination is located in the approximately 40 m thick vadose zone.

The most successful strategy for removing contaminants of this

type from this environment is vapor extraction alone or in

combination with other methods such as air sparging or enhanced bioremediation. Preliminary work at IDS has indicated

that natural pressure differences between surface and subsurface air caused by surface barometric fluctuations can produce

enough gas flow to make barometric pumping a viable method

for subsurface remediation. Air flow and pressure were measured in wells across three stratigraphic intervals in the vadose

zone. The subsurface pressures are correlated to surface pressure fluctuations, but are damped and lagging in phase corresponding to depth and stratum permeability. Piezometer wells

that are screened at lower elevations exhibit a greater phase lag

and damping than wells screened at higher elevations where the

pressure wave from barometric fluctuations passes through a

smaller number of low permeable layers. The phase lag

between surface and subsurface pressures results in significant

fluxes through these wells. The resultant air flows through the

subsurface and impacts CVOC fate and transport. With the

appropriate controls (e.g., solenoid valves) a naturally driven

vapor extraction system can be implemented requiring negligible operating costs, yet capable of a large CVOC removal rate

(as much as 1-2 kg/day in each well at the IDS).

31B

Performance of Horizontal Versus Vertical Vapor

Extraction Wells.

Birdsell, K. H.; Roseberg, N. D.; and Edlund, K. M., Los

Alamos National Laboratory, NM, U.S. Department of

Energy, Washington, DC, June 1994.

 NTIS Document Number: DE94-013643/XAB

Typically, vertical vapor extraction wells are used for site

remediation of volatile organic chemicals in the vadose zone.

Over the past few years, there has been an increased interest in

horizontal wells for environmental remediation. Despite the

Studies and Demonstrations

interest and potential benefits of horizontal wells, there has

been little study of the relative performance of horizontal and

vertical vapor extraction wells. This study uses numerical

simulations to investigate the relative performance of horizontal versus vertical vapor extraction wells under a variety of

conditions. The most significant conclusion drawn from this

study is that in a homogeneous medium, a single, horizontal

vapor extraction well outperforms a single, vertical vapor

extraction well (with surface capping) only for long, linear

plumes. Guidelines are presented regarding the use of horizontal wells.

31C

PFE Process Increases VOC Extraction Rate, Journal

Article: Published in E&P Environment, v5n5, March

1994.

This brief article discusses the benefits of using pneumatic

fracturing in combination with soil vapor extraction (SVE) to

remove contaminants from low-permeability soils. Study results for the extraction of trichloroethane are discussed and the

possibility of extracting other volatile contaminants such as

benzene, toluene, ethylbenzene, and xylene (BTEX) is mentioned. Study results show that air flow rates increased by six

times, and trichloroethane mass removal rates increased by

almost seven times over SVE alone. Contact names and phone

numbers are provided.

31D

Pilot-Scale Studies of Soil Vapor Extraction and

Bioventing for Remediation of a Gasoline Spill at

Cameron Station, Alexandria, Virginia.

Harrison, W.; Joss, C. J.; and Martino, L. E., Argonne

National Laboratory, IL, U.S. Department of Defense,

Washington, DC, July 1994.

 NTIS Document Number: DE94-01776/XAB

Approximately 10,000 gallons of spilled gasoline and unknown

amounts of trichloroethylene and benzene were discovered at

the U.S. Army’s Cameron Station facility. Because the Base

will be closed and turned over to the city of Alexandria in 1995,

the Army sought the most rapid and cost-effective means of

spill remediation. At the request of the Baltimore District of the

U.S. Army Corps of Engineers, Argonne conducted a pilotscale study to determine the feasibility of vapor extraction and

bioventing for resolving remediation problems and to critique

a private firm’s vapor-extraction design. Argonne staff, working with academic and private-sector participants, designed and

implemented a new systems approach to sampling, analysis and

risk assessment. The U.S. Geological Survey’s AIRFLOW

model was adapted for the study to simulate the performance of

possible remediation designs. A commercial vapor-extraction

machine was used to remove nearly 500 gallons of gasoline
32

from Argonne-installed horizontal wells. By incorporating

numerous design comments from the Argonne project team,

field personnel improved the system’s performance. Argonne

staff also determined that bioventing stimulated indigenous

bacteria to bioremediate the gasoline spill. The Corps of

Engineers will use Argonne’s pilot-study approach to evaluate

remediation systems at field operation sites in several states.

32A

Rapid Removal of Underground Hydrocarbon Spills:

Published in Energy and Technology Review, July 1992.

Aines, R; and Newmark, R.

This document provides a general overview of dynamic

underground stripping (DUS). DUS combines in situ steam

injection, electrical resistance heating, and fluid extraction to

rapidly remove and recover subsurface contaminants such as

solvents or fuels. The document discusses overall system

engineering tests of the technology that were conducted at a

“clean site.” Specifically, the results of testing steam injection

and electrical heating capabilities are examined. The article

concludes with a brief discussion of plans to clean up a 17,000

gallon gasoline spill at the site in Lawrence Livermore National

Laboratory in Livermore, California.

32B

Remediation of Low Permeability Subsurface Formations by Fracturing Enhancement of Soil Vapor Extraction, Journal Article: Published in Journal of Hazardous

Materials, v40n2, February 1995.

Frank, U. and Barkley, N., U.S. Environmental Protection

Agency Risk Reduction Engineering Lab, Cincinnati, OH,

Environmental Protection Agency, February 1995.

This article provides an overview of the Superfund Innovative

Technology Evaluation (SITE) of hydraulic and pneumatic

fracturing. Hydraulic and pneumatic fracturing are used to

enhance the ability of technologies such as SVE to remove

volatile contaminants from the soil. The article includes results

from several demonstrations which show orders of magnitude

increases in subsurface vapor flow and contaminated vapor

extraction rates when hydraulic or pneumatic fracturing is

applied. The article also indicates that fracturing is most

beneficial when used on tightly packed soil having low permeability.

32C

Researchers Aim to Make Pump and Treat Technology

Obsolete, Journal Article: Published in Environment

Week, v6n49, December 1993.

This article discusses the results of a pilot test which used steam

and electric heating in combination with soil vapor extraction

(SVE) to clean up an underground gasoline spill in Livermore,

California. The pilot test was sponsored by the Lawrence

Livermore National Laboratory and the University of California at Berkeley. The project involved removing 7,800 gallons

of gasoline from approximately 80,000 cubic yards of soil. The

combination of steam and electric heating, referred to as “dynamic” underground stripping, is discussed as an innovative

alternative to conventional “pump and treat” technologies. The

article also discusses future plans for additional tests of “dynamic” underground stripping which include using the technology for the removal of trichloroethylene. Imaging technology

used in conjunction with the stripping system is also discussed.

32D

SITE Technology Demonstration Summary: Accutech

Pneumatic Fracturing Extraction and Hot Gas Injection,

Phase I, Federal Government Report.

Skovronek, H. S., U.S. Environmental Protection Agency,

Risk Reduction Engineering Laboratory, Cincinatti, OH,

August 1993.

 EPA Document Number: EPA/540/SR-93/509

EPA’s Superfund Innovative Technology Evaluation (SITE)

program promotes the development of innovative technologies

that will reduce pollution at hazardous waste sites. To improve

vapor extraction from the vadose zone, Pneumatic Fracturing

Extraction (PFE) has been developed by Accutech Remedial

Systems. PFE involves the creation of new fractures and

enlargement of older fractures by injecting bursts of compressed air into narrow wellbores. Results are presented from

PFE tests to extract trichloroethene (TCE) from a contaminated

industrial site in New Jersey. Compression-heated air was

injected into a central well and was extracted from one or more

monitoring wells. Temperature, air-flow rates, and TCE mass

removal rates were monitored. Results indicated that only very

low concentrations of TCE were found in the extracted air, both

before and during hot-air injection. When tests were conducted

at another area of the contaminated site, where higher TCE

concentrations were anticipated, the TCE mass removal rate

increased by about 50 percent. Cost data on the new technology, which appears attractive for VOC-contaminated formations with low permeability, are considered.

32E

Six-Phase Soil Heating Accelerates VOC Extraction

From Clay Soil, Conference Literature.

Gauglitz, P. A.; Roberts, J. S.; Bergsman, T. M.;

Caley, S. M.; Heath, W. O., Battelle Pacific Northwest

Labs., Richland, WA, International Nuclear and Hazardous

Waste Management Conference, Atlanta, GA, August 14-18,

August 1994.

Studies and Demonstrations
33

Six-Phase Soil Heating (SPSH) was demonstrated as a viable

technology for heating low permeability soils containing volatile organic contaminants. Testing was performed as part of the

Volatile Organic Compounds in Non-Arid Soils Integrated

Demonstration (VOC Non-Arid ID) at the Savannah River Site.

The soil at the integrated demonstration site is contaminated

with perchloroethylene (PCE) and trichloroethylene (TCE); the

highest soil contamination occurs in clay-rich zones that are

ineffectively treated by conventional soil vapor extraction due

to the very low permeability of the clay. The SPSH demonstration sought to heat the clay zone and enhance the performance

of conventional soil vapor extraction. Soil samples were

collected before and after heating to quantify the efficacy of

heat-enhanced vapor extraction of PCE and TCE from the clay

soil. Results show that contaminant removal from the clay zone

was 99.7% (median) within the electrode array. Outside the

array where the soil was heated, but to only 50(degrees)C, the

removal efficiency was 93%, showing that heating accelerated

the removal of VOCs from the clay soil.

33A

Soil and Groundwater Restoration by Steam Enhanced

Extraction, Journal Article: Published in Ground Water,

v31n5, September-October 1993.

Udell, K. S., Association of Groundwater Scientists and

Engineers (AGWSE) Educational Seminar on Chlorinated

Volatile Organic Compounds in Groundwater.

The acceleration of recovery rates of second phase liquid

contaminants from the subsurface during gas or water pumping

operations is realized by increasing the soil and groundwater

temperature. Several methods of delivery of thermal energy to

soils and groundwater are possible. Of these methods, steam

injection combined with groundwater pumping and vacuum

extraction appears to be the most economical and versatile

technique to recover volatile, semivolatile, and nonvolatile

contaminants from the subsurface. One-dimensional experiments have shown effective removal of both volatile and

semivolatile second liquid phase chemicals, and nonvolatile

aqueous phase contaminants from sand packs. Two-dimensional experiments with homogeneous and layered sand packs

have shown rapid recovery of semivolatile hydrocarbon liquids

and dense chlorinated solvents. The enhancement of mass

transfer from lower permeability regions during the depressurization mode of operation has been observed. As a result of

these experiments, several mechanisms have been identified

which account for the observed removal of the contaminants.

These are vaporization of components with low boiling points,

enhanced evaporation rates of semivolatile components, physical displacement of low viscosity liquids, dilution and displacement of aqueous contaminants, and removal of residual contaminants by vacuum drying. Field-scale studies of steam

injection and vacuum extraction confirm the effectiveness of

this technique and its applicability to contaminants found above

and below the water table.

33B

Soil Vapor Extraction From Hydraulic Fractures in

Glacial Till: Initial Field Testing in Chicago, Illinois,

Conference Literature.

Schroeder, S. D.; McKenzie, D. B.; and Murdoch, L. C.,

85th Annual Meeting of the Air Waste Management Association (AWMA), Air and Waste Management Association,

June 1992.

Hydraulic fracturing, used for several decades to increase the

yield from oil and water wells, may increase the effectiveness

of in situ remedial technologies in glacial till. Three fractures

at each of two locations were created at a Chicago study site at

depths of 6 to 12 feet by the University of Cincinnati-Center Hill

to evaluate the impact of hydraulic fracturing on the SVE

process. SVE wells were installed to access each of the

fractures, and two SVE wells were installed in native till to

serve as a control. Soil pore-pressure probes were installed to

measure air pressure as a function of depth and radial distance.

At depths of 3 feet or less, the radius of influence of the fractured

wells was approximately 20 feet, whereas the radius of influence of the nonfractured wells was only 13 feet of influence of

the fractured well was at least 5 feet at depths of 7 feet, whereas

the radius was 3 feet. Well yields from fractured and nonfractured

wells were approximately 1 to 1.5 cfm with an applied vacuum

of 9 to 11 inches Hg. Well yields decreased as soil pore water

accumulated within the extraction wells.

33C

Steam Injection/Vacuum Extraction, Phase 2,

Treatability Investigation, Site Characterization, and

Design, Final Report.

Heglie, J.; Koster, R.; Pexton, R.; and Stewart, L., CH2M/

Hill, Sacramento, CA, December 1991.

 NTIS Document Number: AD-A243745/7/XAB

The U.S. Air Force is planning to conduct a pilot test of steam

injection and vapor extraction remediation technology at

McClellan AFB. This innovative technology, under development by Kent Udell at the University of California at Berkeley,

combines in situ steam injection into soil in both the vadose

(unsaturated) and saturated zone, with vacuum extraction of

volatile and semi volatile organic contaminants from the soil.

Results of the composite soil samples received to date show the

presence of dioxins and dibenzofurans, petroleum hydrocarbons, volatile organics, semi volatile organics, and polychlorinated biphenyls in the waste fill material. Results of the

treatability testing indicate that: (1) low concentrations of

dioxins and furans were mobilized by the steam condensate; (2)

high concentrations of hydrocarbons were reduced by one

order-of-magnitude by the steam; and (3) dioxins and furans

appeared to be dissolved mainly in the hydrocarbon nonaqueous

phase liquid (NAPL) phase. Petroleum hydrocarbon and dioxin

Studies and Demonstrations
34

Other Resources Guides

34C

Using Geophysical Techniques to Control In Situ Thermal Remediation, Symposium.

Boyd, S.; Daily, W.; Ramirez, A.; Wilt, M.; and Goldman,

R., Lawrence Livermore National Laboratory, CA, U.S.

Department of Energy, Washington, DC, January 1994.

 NTIS Document Number: DE94-006722/XAB

Monitoring the thermal and hydrologic processes that occur

during thermal environmental remediation programs in near

real-time provides essential information for controlling the

process. Geophysical techniques have played a crucial role in

process control as well as characterization during the recent

Dynamic Underground Stripping Project demonstration. The

demonstration removed several thousand gallons of gasoline

from heterogeneous soils both above and below the water table.

Dynamic Underground Stripping combines steam injection and

electrical heating for thermal enhancement with groundwater

pumping and vacuum extraction for contaminant removal.

These processes produce rapid changes in the subsurface properties including changes in temperature, fluid saturation, pressure, and chemistry. Subsurface imaging methods are used to

map the heated zones and control the thermal process. Temperature measurements made in wells throughout the field

reveal details of the complex heating phenomena. Electrical

resistance tomography (ERT) provides near real-time detailed

images of the heated zones between boreholes both during

electrical heating and steam injection. Borehole induction logs

show close correlation with lithostratigraphy and, by identifying the more permeable gravel zones, can be used to predict

steam movement. They are also useful in understanding the

physical changes in the field and in interpreting the ERT

images. Tiltmeters provide additional information regarding

the shape of the steamed zones in plan view. They were used

to track the growth of the steam front from individual injectors.

OTHER RESOURCE GUIDES

34D

Bioremediation Resource Guide.

U.S. Environmental Protection Agency, Office of Solid

Waste and Emergency Response, Technology Innovation

Office, Washington, DC, September 1993.

(see abstract below)

 EPA Document Number: EPA/542/B-93/004

concentrations were not high enough to preclude a pilot scale

test.

34A

Two U.S. EPA Bioremediation Field Initiative Studies:

Evaluation of In Situ Bioventing, Eighteenth Annual Risk

Reduction Engineering Laboratory Research Symposium, Conference Literature.

Sayles, G. D.; Brenner, R. C.; Hinchee, R. E.; Vogel, C. M.;

and Miller, R. N., Eighteenth Annual U.S. Environmental

Protection Agency (EPA) Risk Reduction Engineering

Laboratory Research Symposium, Cincinnati, OH, April

1992.

Bioventing is the process of supplying oxygen in situ to oxygendeprived soil microbes by forcing air through contaminated soil

at low air flow rates. Unlike soil venting or soil vacuum

extraction technologies, bioventing attempts to stimulate

biodegradative activity while minimizing stripping of volatile

organics. The process destroys the toxic compounds in the

ground. Bioventing technology is especially valuable for

treating contaminated soils in areas where structures and utilities cannot be disturbed because the equipment needed (air

injection/withdrawal wells, air blower, and soil gas monitoring

wells) is relatively non-invasive. The U.S. EPA Risk Reduction

Engineering Laboratory, with resources from the U.S. EPA

Bioremediation Field Initiative, began two parallel 2 year field

studies in collaboration with the U.S. Air Force. The field sites

are located at Eielson Air Force Base (AFB) near Fairbanks,

Alaska, and Hill AFB near Salt Lake City, Utah. Each site has

jet fuel JP-4 contaminated unsaturated soil where a spill has

occurred in association with a fuel distribution network. With

the pilot-scale experience gained in these studies and others,

bioventing should be available in the very near future as an

inexpensive, unobtrusive means of treating large quantities of

organically contaminated soils.

34B

U.S. Environmental Protection Agency’s Superfund

Innovative Technology Evaluation of Pneumatic Fracturing ExtractionSM, Journal Article: Published in Air &

Waste Management Association Journal, v44, October

1994.

Frank, U., U.S. Environmental Protection Agency, Edison, NJ.

This document describes the field demonstration of Pneumatic

Fracturing Extraction (PFE)SM performed by EPA, in cooperation with Accutech Remedial Systems and the New Jersey

Institute of Technology. This demonstration focused on extracting chlorinated volatile organic compounds (VOCs) from

vadose zones of low permeability. This document describes the

demonstration, and indicates the estimated cost of using PFE

and the favorable extraction rates obtained with this technology.
35

35A

Ground Water Treatment Technology Resource Guide.

U.S. Environmental Protection Agency, Office of Solid

Waste and Emergency Response, Technology Innovation

Office, Washington, DC, September 1994.

(see abstract below)

 EPA Document Number: EPA/542/B-94/009

35B

Physical/Chemical Treatment Technology Resource

Guide.

U.S. Environmental Protection Agency, Office of Solid

Waste and Emergency Response, Technology Innovation

Office, Washington, DC, September 1994.

(see abstract below)

 EPA Document Number: EPA/542/B-94/008

35C

Soil Vapor Extraction (SVE) Treatment Technology

Resource Guide.

U.S. Environmental Protection Agency, Office of Solid

Waste And Emergency Response, Technology Innovation

Office, Washington, DC, September 1994.

 EPA Document Number: EPA/542-B-94/007

These documents are intended to support decision-making by

Regional and State Corrective Action permit writers, Remedial

Project Managers (RPMs), On-Scene Coordinators, contractors, and others responsible for the evaluation of innovative

treatment technologies. These guides direct managers of sites

being remediated under RCRA, UST, and CERCLA to

bioremediation, ground-water, physical/chemical, and soil vapor extraction treatment technology resource documents; databases; hotlines; and dockets, and identify regulatory mechanisms (e.g., Research Development and Demonstration Permits) that have the potential to ease the implementation of these

technologies at hazardous waste sites. Collectively, the guides

provide abstracts of over 300 guidance/workshop reports, overview/program documents, studies and demonstrations, and

other resource guides, as well easy-to-use Resource Matrices

that identify the technologies and contaminants discussed in

each abstracted document.
36

United States

Environmental Protection

Agency

Office of Solid Waste and

Emergency Response

Technology Innovation Office

Washington, DC 20460

EPA/542-B-95-003

October 1995

Soil Vapor Extraction (SVE)

Enhancement Technology

Resource Guide

• Air Sparging

• Bioventing

• Fracturing

• Thermal Enhancements

EPA
37

Soil Vapor Extraction (SVE)

Enhancement Technology

Resource Guide

• Air Sparging

• Bioventing

• Fracturing

• Thermal Enhancements

U.S. Environmental Protection Agency

Office of Solid Waste and Emergency Response

Technology Innovation Office

Washington, D.C. 20460

October 1995
38

FOREWORD

Identifying and accessing pertinent information resources that will help site cleanup managers evaluate innovative

technologies is key to the broader use of these technologies. This Guide is intended to increase awareness about

technical information and specialized support services/resources related to soil vapor extraction enhancement

technologies.

Specifically, this document identifies a cross section of information intended to aid users in remedial decisionmaking, including abstracts of field reports and guidance documents and information to assist in the ordering of

publications. In addition, the look-up format of this document allows the user to quickly scan available resources

and access more detailed abstracts.

Please let us know about additional information that could make this Guide (and others in the series) more useful

to you.

Walter W. Kovalick, Jr., Ph.D.

Director, Technology Innovation Office
39

This document was prepared by the United States Environmental Protection Agency (EPA) under EPA Contract Number

68-W2-0004, Subcontract Number 92-001-01. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

This document is part of a series of technology resource guides prepared by the Technology Innovation Office. The series

includes the following technology guides: the Bioremediation Resource Guide (EPA/542/B-93/004); the Ground-Water

Treatment Technology Resource Guide (EPA/542/B-94/009); the Physical/Chemical Treatment Technology Resource Guide

(EPA/542/B-94/008); and the Soil Vapor Extraction Resource Guide (EPA/542/B-94/007).

NOTICE
40

TABLE OF CONTENTS

INTRODUCTION.....................................................................................................................................1

HOW TO USE THIS GUIDE ...................................................................................................................2

HOW TO ORDER DOCUMENTS LISTED IN THIS GUIDE ...................................................................3

TECHNOLOGY SUMMARIES AND MATRICES ...................................................................................4

AIR SPARGING .............................................................................................................................4

BIOVENTING .................................................................................................................................6

FRACTURING................................................................................................................................8

THERMAL ENHANCEMENTS ....................................................................................................10

ABSTRACTS OF SOIL VAPOR EXTRACTION ENHANCEMENT TECHNOLOGY

RESOURCES .......................................................................................................................................13

GUIDANCE DOCUMENTS ...................................................................................................................13

OVERVIEW/PROGRAM DOCUMENTS...............................................................................................14

STUDIES AND DEMONSTRATIONS - TEST DESIGN .......................................................................23

STUDIES AND DEMONSTRATIONS - STUDY RESULTS .................................................................25

OTHER RESOURCE GUIDES .............................................................................................................34