United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPA/540/R-94/529
August 1995
&EPA
Subsurface Volatilization and
Ventilation System (SVVSf
Innovative Technology
Evaluation Report
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
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NOTICE
The information in this document has been prepared for the U.S. Environmental Protection Agency s
(EPA's) Superfund Innovative Technology Evaluation (SITE) Program under Contract No. 68-CO-0048. This
document is draft and will be subjected to the EPA's peer and administrative reviews prior to approval for
publication as an EPA document. Mention of trade names of commercial products does not constitute an
endorsement or recommendation for use.
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FOREWORD
The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation's land,
air, and water resources. Under a mandate of national environmental laws, the Agency strives to formulate and
implement actions leading to a compatible balance between human activities and the ability of natural systems
to support and nurture life. To meet this mandate, EPA's research program is providing data and technical
support for solving environmental problems today and building a science knowledge base necessary to manage
our ecological resources wisely, understand how pollutants affect our health, and prevent or reduce environmental
risks in the future.
The National Risk Management Research Laboratory is the Agency's center for investigation of
technological and management approaches for reducing risks from threats to human health and the environment.
The focus of the Laboratory's research program is on methods for the prevention and control of pollution to air,
land, water and subsurface resources; protection of water quality in public water systems ; remediation of
contaminated sites and ground water; and prevention and control of indoor air pollution. The goal of this research
effort is to catalyze development and implementation of innovative, cost-effective environmental technologies;
develop scientific and engineering information needed by EPA to support regulatory and policy decisions; and
provide technical support and information transfer to ensure effective implementation of environmental
regulations and strategies.
This publication has been produced as part of the Laboratory's strategic long-term research plan. It is
published and made available by EPA's Office of Research and Development to assist the user community and
to link researchers with their clients.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
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TABLE OF CONTENTS
Section
Page
NOTICE ii
FOREWORD iii
LIST OF TABLES viii
LIST OF FIGURES ix
ACRONYMS, ABBREVIATIONS, AND SYMBOLS x
ACKNOWLEDGEMENTS xiv
EXECUTIVE SUMMARY 1
SECTION 1 INTRODUCTION 8
1.1 Background 8
1.2 Brief Description of Program and Reports 9
1.3 The SITE Demonstration Program 10
1.4 Purpose of the Innovative Technology Evaluation Report (ITER) 11
1.5 Technology Description 12
1.6 Key Contacts 13
SECTION 2 TECHNOLOGY APPLICATIONS ANALYSIS 15
2.1 Key Features 15
2.2 Operability of the Technology 16
2.3 Applicable Wastes 19
2.4 Availability and Transportability of the Equipment 20
2.5 Materials Handling Requirements 20
2.6 Site Support Requirements 21
2.7 Ranges of Suitable Site Characteristics 22
2.8 Limitations of the Technology 24
2.9 ARARs for the SWS* Technology 25
2.9.1 Comprehensive Environmental Response, Compensation and Liability
Act (CERCLA) : 30
2.9.2 Resource Conservation and Recovery Act (RCRA) 31
2.9.3 Clean Air Act (CAA) 32
2.9.4 Clean Water Act (CWA) 33
2.9.5 Safe Drinking Water Act (SDWA) 34
2.9.6 Toxic Substances Control Act (TSCA) 34
2.9.7 Occupational Safety and Health Administration (OSHA)
Requirements 34
2.9.8 State Requirements 36
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TABLE OF CONTENTS (Continued)
tion
SECTION 3
Page
ECONOMIC ANALYSIS 37
3.1 Introduction 37
3.2 Conclusions 38
3.3 Issues and Assumptions 3°
3.3.1 Waste Volumes and Site Size 38
3.3.2 System Design and Performance Factors 39
3.3.3 System Operating Requirements 39
3.3.4 Financial Assumptions 40
3.4 Basis for Economic Analysis 40
3.4.1 Site Preparation 40
3.4.2 Permitting and Regulatory Requirements 42
3.4.3 Capital Equipment 42
3.4.4 Startup 43
3.4.5 Consumables and Supplies 43
3.4.6 Labor : 43
3.4.7 Utilities 44
3.4.8 Effluent Treatment and Disposal 44
3.4.9 Residuals & Waste Shipping, Handling, and Storage 45
3.4.10 Analytical Services 45
3.4.11 Facility Modification, Repair, and Replacement 45
3.4.12 Demobilization 46
3.5 Results 46
SECTION 4 TREATMENT EFFECTIVENESS 48
4.1 Background 48
4.2 Detailed Process Description 50
4.3 Methodology 53
4.4 Performance Data 56
4;4.1 Results from Pre-Treatment Study 56
4.4.2 Summary of Results -- Primary Objectives 56
4.4.3 Changes in Individual Critical VOCs 58
4.4.4 Effect of the S WS® on VOCs in the Saturated Soil and Groundwater
Within the Treatment Plot 70
VI
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TABLE OF CONTENTS (Continued)
Page
4.4.5 Effect of the SWS® on VOCs in the Groundwater Outside of the
Treatment Plot 71
4.4.6 Impact of Soil Conditions on the SWS* 71
4.4.7 Extracted Vapor Assessment 72
4.4.8 Impact of Biodegradation on Contaminant Removal 75
4.4.9 Performance of the BEC*Unit 76
4.4.10 Process Operability and Performance at the Electro-Voice Site 76
4.5 Process Residuals 78
SECTION 5 OTHER TECHNOLOGY REQUIREMENTS 79
5.1 Environmental Regulation Requirements 79
5.2 Personnel Issues 79
5.3 Community Acceptance 80
SECTION 6 TECHNOLOGY STATUS 81
6.1 Previous/Other Experience 81
REFERENCES 82
APPENDIX A VENDOR'S CLAIMS 84
APPENDIX B CONVERSIONS 90
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Table
Table ES-1
Table 2-1
Table 3-1
Table 4-1
Table 4-2
LIST OF TABLES
Evaluation Criteria for the Environmental Improvement Technologies, Inc.
SWS® Vapor Extraction/Air Sparging and In-Situ
Bioremediation Technology
Page
Federal and State Applicable and Relevant and Appropriate
Requirements (ARARs) for the SWS® Technology ............................ 27
Estimated Cost for Treatment Using the SWS® Process Over a
Three Year Application .................................................. 41
SWS® Performance Summary Zone 1 Vadose Soils ............................. 59
Summary of the Reductions of Individual Critical VOCs
WithinZone 1 Vadose Soils ................................................ 67
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LIST OF FIGURES
Figure Page
Figure 3-1 Remediation Cost Breakdown (3 yrs.) 47
Figure 4-1 Configuration of the SWS® at the Electro-Voice Site 52
Figure 4-2 Pre-Treatment Sampling Locations at the Electro-Voice Site 55
Figure 4-3 Revised Post-Treatment Sampling Locations at the Electro-
Voice Site 57
Figure 4-4 SWS* Performance by Horizon 60
Figure 4-5 Percent Reduction as a Function of Initial VOC Concentration 61
Figure 4-6 Contaminant Map -- Pre (a) and Post (b) Treatment .-- Entire
Vadose Zone , 62
Figure 4-7 Contaminant Map - Pre (a) and Post (b) Treatment ~ Upper
Horizon 63
Figure 4-8 Contaminant Map ~ Pre (a) and Post (b) Treatment ~ Sludge
Layer 64
Figure 4-9 Contaminant Map - Pre (a) and Post (b) Treatment ~ Lower
Horizon A 65
Figure 4-10 Contaminant Map — Pre (a) and Post (b) Treatment — Lower
Horizon B 66
Figure 4-11 Magnitude of Reduction of Individual Critical VOCs 68
Figure 4-12 Relative Distribution of Individual Soil VOCs Before and After
Treatment 69
Figure 4-13 Extracted Vapor Stream Over Time 73
Figure 4-14 Relative Distribution of Individual Air Stream VOCs Before and
After Treatment 74
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ACRONYMS, ABBREVIATIONS AND SYMBOLS
ug Microgram
Hg/kg Micrograms per kilogram
Hg/1 Micrograms per liter
AO Administrative Order
AQCR Air Quality Control Regions
AQMD Air Quality Management District
ARAR Applicable or relevant and appropriate requirement
ATTIC Alternative Treatment Technology Information Center
BAI Billings and Associates, Inc.
BEC® Biological Emission Control
B&RE Brown & Root Environmental
BTEX Benzene, toluene, ethylbenzene, and xylenes
CAA Clean Air Act
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
CERI Center for Environmental Research Information
cfin Cubic feet per minute
CFR Code of Federal Regulations
C02 Carbon Dioxide
CWA Clean Water Act
DCE Dichloroethene
DNAPLs Dense non-aqueous phase liquids
DNR Department of Natural Resources
dscfrn Dry standard cubic feet per minute
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ACRONYMS, ABBREVIATIONS AND SYMBOLS (Continued)
BIT Environmental Improvement Technologies
EPA U.S. Environmental Protection Agency
BSD Explanation of Significant Difference
EV Electro-Voice, Inc.
FS Feasibility Study
ITER Innovative Technology Evaluation Report
kg Kilogram
kW Kilowatt
kWh Kilowatt-hour
MCL Maximum contaminant levels
MCLG Maximum contaminant level goals
mg/kg Milligrams per kilogram
mg/1 Milligrams per liter
NAAQS National Ambient Air Quality Standards
NCP National Oil and Hazardous Substances Pollution Contingency Plan
NPDES National Pollutant Discharge Elimination System
NTIS National Technical Information Service
ORD EPA Office of Research and Development
OSHA Occupational Safety and Health Act
OSWER Office of Solid Waste and Emergency Response
OU Operable Unit
PCB Polychlorinated biphenyl
PCE Tetrachloroethene
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ACRONYMS, ABBREVIATIONS AND SYMBOLS (Continued)
POTW Publicly-owned treatment works
PPE Personal protective equipment
PSD Particle size distribution
RCRA Resource Conservation and Recovery Act
RI Remedial Investigation
ROD Record of Decision
RREL Risk Reduction Engineering Laboratory
S.U. Standard Units
SAIC Science Applications International Corporation
SARA Superfund Amendments and Reauthorization Act
SDWA Safe Drinking Water Act
SITE Superfund Innovative Technology Evaluation
SVE Soil-Vapor Extraction
S WS® Subsurface Volatilization and Ventilation System®
SWDA Solid Waste Disposal Act
TC Total Carbon
TCE Trichloroethene
TER Technology Evaluation Report
THC Total Hydrocarbons
TIC Total Inorganic Carbon
TKN Total Kjeldahl Nitrogen
TSCA Toxic Substances Control Act
UST Underground Storage Tank
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ACRONYMS, ABBREVIATIONS AND SYMBOLS (Continued)
VCU Vapor Control Unit
VISITT Vendor Information System for Innovative Treatment Technologies
VOC Volatile Organic Compound
yd3 Cubic yards
Xlll
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ACKNOWLEDGEMENTS
This report was developed under the direction of Mr. John Martin, the EPA Technical Project Manager
for this SITE Demonstration at the Risk Reduction Engineering Laboratory (RREL) in Cincinnati, Ohio. Prior
to Mr. Martin, project direction and coordination was provided by Ms. Kim Kreiton, formerly with the USEPA-
RREL.
This report was prepared by the Environmental Technology Division of Science Applications
International Corporation (SAIC), Hackensack, New Jersey under the direction of Mr. John J. King, the SAIC
Work Assignment Manager, for the U.S. Environmental Protection Agency under Contract No. 68-CO-0048.
This report was written in large part by Dr. Scott Beckman and Mr. Omer Kitaplioglu. Statistical analyses and
the experimental design were developed by Al linger and Dan Patel. Project Quality Assurance was provided
by Ray Martrano and Rita Stasik. Field management responsibilities were shared between Mike Bolen and Andy
Matuson. Field geologist responsibilities were conducted by Paul Feinberg. Field health and safety coordination
was provided by Brandon Phillips.
The cooperation and participation of Mr. Timothy Mayotte, Mr. Steve Thompson and supporting staff
of Brown & Root Environmental throughout the course of the project and in review of this report are gratefully
acknowledged.
Ms. Beth Reiner and Ms. Eugenia Chow, the Remedial Project Managers of USEPA's Region V provided
invaluable assistance and guidance in initiating the project and in interpreting and responding to regulatory needs.
Special thanks are offered to Mr. Ronald Graham and the employees of Electro-Voice for their hospitality
and assistance throughout this SITE Demonstration.
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EXECUTIVE SUMMARY
This report summarizes the findings associated with a Demonstration Test of Environmental
Improvement Technologies' (BIT) Subsurface Volatilization and Ventilation System (SWS*) process. The
technology was evaluated under the EPA Superfund Innovative Technology Evaluation (SITE) Program in
conjunction with an independent one-year testing of the technology to provide justification for the execution of
an Explanation of Significant Difference (BSD) to the Record of Decision (ROD) for Operable Unit (OU)
Number One. Under the SITE Program, the technology was evaluated to determine its effectiveness in reducing
volatile organic contamination in the vadose zone of the former "dry well area" of the Electro-Voice facility after
one year of treatment. The technology was evaluated against the nine criteria for decision-making in the
Superfund Feasibility Study process. The results of this evaluation are presented in Table ES-1.
The SWS* process is an integrated technology that utilizes the benefits of soil vapor extraction/air
sparging and in-situ bioremediation for the treatment of subsurface organic contamination in soil and
groundwater. The SWS* process evaluated under the USEPA SITE Program was developed and designed by
Billings and Associates, Inc. (BAI) and operated by Brown & Root Environmental (B&RE)(formerly Halliburton
NUS Environmental Corporation)(For the purposes of this report, BAI and B&RE are referred to as the developer
and operator, respectfully). The SWS® process uses vapor extraction to remove the easily-strippable volatile
components and biostimulation to remove the less volatile more tightly sorbed components. Vapor extraction
appears to be the more dominant removal mechanism during the early phases of treatment, while biostimulation
processes dominate in later phases. During the early stages of system application, when vapor extraction is the
dominant treatment mechanism, the extracted vapors might need to be treated above ground before release to the
atmosphere. During this period, which can last anywhere from two weeks to a few months, the developer claims
that system off-gasses can be treated by BAI's Biological Emission Control (EEC)* biofilters, alone or in
combination with conventional activated carbon or other mechanisms for additional air polishing. The developer
claims that remediation using the combination of vapor extraction and biostimulation is more rapid than the use
of biostimulation alone, while generating lower quantities of volatile organic emissions than vapor extraction
technologies. In addition, the SWS® can remediate contaminants that would not be remediated by vapor
extraction alone (chemicals with lower volatilities and /or chemicals that are tightly sorbed). These benefits
translate into lower costs and faster remediations.
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OVERALL PROTECTION OF
HUMAN HEALTH AND THE
ENVIRONMENT
TABLE ES-1 EVALUATION CRITERIA FOR THE ENVIRONMENTAL IMPROVEMENT TECHNOLOGIES, INC.
SWS* VAPOR EXTRACTION/AIR SPARGING AND BV-SITU BIOREMEDIATION TECHNOLOGY
REDUCTION OF TOXICITY,
MOBILITY, OR VOLUME
THROUGH TREATMENT
COMPLIANCE WITH
FEDERAL ARARs
LONG TERM EFFECTIVENESS
AND PERMANENCE
Protects human health and the
environment by removing and
destroying organic contaminants from
liquid, aqueous, sorbed, and vapor
phases in soil
and groundwater.
Requires compliance with RCRA
treatment, storage, and disposal
regulations (if hazardous wastes
are present).
Effectively destroys or removes
organic contamination from affected
matrix.
Significantly reduces the toxicity of
organic contaminants as
biodegradation converts contaminants
to non-toxic by-products (CO2 and
H20).
Remediation can be performed
in-situ, reducing the need for
excavation.
Operation of on-site treatment
system may require compliance
with location-specific ARARs.
Volume of contaminants is
significantly reduced as contaminants
are removed by vapor extraction and
biodegraded by indigenous microbes
Off-gas treatment system
reduces airborne emissions. Air
emissions can be favorably controlled
within regulatory limits by adjusting
the rate of air injection and extraction.
Minimal wastewater discharges to
POT Ws may require pre-treatment to
comply with the Clean Water Act or
Safe Drinking Water Act, depending
on the contaminant.
Off-gas treatment system is used
initially to reduce emissions, until
biodegradation rate exceeds rate of
contaminant mass transfer to the vapor
phase.
Technology is primarily suited to
remove and destroy subsurface
organic contaminants. Can be used to
treat heavy metals in groundwater by
raising redox potential and inducing
metals to precipitate.
Emission control may be needed to
ensure compliance with air quality
standards depending upon local
ARARs.
Some treatment residues (drill
cuttings, decontamination water,
condensate, spent activated carbon
and personal protective equipment)
might require special disposal
requirements. Condensate can be
used as make-up water for the BEC*
units.
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SHORTTERM
EFFECTIVENESS
EMPLEMENTABILJTY
COST
COMMUNITY
ACCEPTANCE
STATE
ACCEPTANCE
Treatment of a site using
S WS* removes and destroys
subsurface organic
contaminants.
Hardware components used to
construct and operate the
SVVS* are common and
readily available.
The cost for remediation,
assuming that no off-gas
treatment is necessary, is
$10.36/yd3.
Minimal short-term risks to the
community make this technology
appealing to the public.
State ARARs may be
more stringent than
federal regulations.
Presents potential short-term
chemical exposure risks to
workers installing a system
due to the potential for
fugitive emissions being
generated during excavation
and construction.
Utility needs are minor
(electricity, water and sewer,
if possible).
Site preparation is the most
significant cost associated
with SVVS* representing
28% of the overall cost.
Residuals handling and
disposal and analytical
services are the next largest
cost component.
Technology is generally accepted
by the public because it provides a
permanent solution.
State acceptance of the
technology varies
depending upon ARARs.
CO
Depending on the volatility
and biodegradability of
organic contaminants, the
highest mass removal rates
can be experienced at the
beginning of treatment.
The SVVS* is installed in-
place and is custom- designed
for a site. An average system
can take up to a month to
install before being ready to
operate. The technology is
not considered mobile.
Labor accounts for a
relatively small percentage of
the overall cost (9%).
Noise generated during system
installation could be troublesome,
but once the system is operational,
it does not generate much
appreciable noise.
Each SVVS* system is
site-specific, and can be
designed to meet state
criteria.
Some short-term risks
associated with vacuum
extraction off-gas emissions
might exist during the early
stages of treatment when the
rate of vapor extraction
exceeds the rate of
biodegradation. Depending
on site requirements, the risks
can be reduced by an
emission treatment system.
Support equipment during
system installation includes
drill rigs, trenchers, and
possibly backhoes, front-end
loaders and fork lifts.
'If off-gas polishing is
required, above-ground air
treatment costs could account
for 43% of the total cleanup
cost, depending on the air
treatment train selected.
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SHORT TERM
EFFECTIVENESS
IMPLEMENTABILrrY
COST
COMMUNITY
ACCEPTANCE
STATE
ACCEPTANCE
A site's physical and chemical
conditions must be adequately
defined to optimize system
design and installation.
The cost for system expansion
is typically no more than 10-
20% of total cleanup cost due
to the simplicity of system
construction and reserved
capacity of vacuum and
injection pumps.
The technology is not
recommended for remediation
of materials of very low
permeability.
Actual cost of a remedial technology is site-specific and is dependent on factors such as the cleanup level, contaminant concentrations and types, waste characteristics,
and volume necessary for treatment. Cost data presented in this table are for treating 21,300 yd3 of soil.
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The SWS* technology was tested at the Electro-Voice, Inc. site in Buchanan, Michigan to assess the
developer's claim that the system would reduce the average contamination of seven target contaminants in the
vadose zone by 30% after one year of system operation. This became the critical objective of the SITE
Demonstration. The one-year time frame was chosen for testing purposes only, and does not reflect the limits
of the technology. The technology was evaluated for a number of secondary objectives all of which are discussed
in this Innovative Technology Evaluation Report.
CONCLUSIONS BASED ON CRITICAL OBJECTIVE
The SWS® achieved an overall 80.6% reduction in the sum of the seven critical VOCs in the vadose
zone after one year of system operation. This level of reduction greatly exceeded the developer's claim which
promised a 30% reduction over a one-year time frame. The average concentrations of the sum of the seven
critical analytes (benzene, toluene, ethylbenzene, xylenes, trichloroethene, tetrachloroethene, and 1,1-
dichloroethene) in the study area before and after one year of operation were 341.5 mg/kg and 66.2 mg/kg,
respectively. Reductions for each subsurface horizon revealed an 81.5% reduction for the "sludge layer", the most
contaminated horizon throughout the treatment plot, and 97.8% to 99.8% for all other vadose zone horizons.
When evaluating system performance by comparing VOC concentrations in matched boreholes before and after
one year of treatment, contaminant reductions ranged from 71% to 99%. This indicated that the system operated
relatively uniformly over the entire vadose zone of the treatment plot, and no significant untreated areas were
encountered, regardless of initial VOC concentration or lithology.
CONCLUSIONS BASED ON SECONDARY OBJECTIVES
The studies conducted by the SITE Program suggest the following conclusions regarding the technology's
performance at the Electro-Voice site. These conclusions were based upon secondary project objectives and are
presented as follows:
An analysis of individual VOC contaminants in the vadose zone before and after treatment revealed
reductions that ranged from 78% to 92%. Xylenes, the most prevalent compound, comprising 60% of
the VOCs in the treatment plot, were reduced by 78%, whereas tetrachloroethene, which represented
1.6% of the total VOC concentration in the vadose zone, exhibited a reduction of 92%. The relative
distribution of individual compounds in vadose zone soils is similar before and after treatment,
suggesting that the technology at this site did not appear to selectively remove or destroy one component
over another.
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The technology was evaluated for its ability to reduce VOC contamination in groundwater within the
treatment plot. The lack of detectable levels of contamination in the groundwater during system
operation precluded any meaningful evaluation of the systems performance on groundwater within the
physical boundaries of the treatment plot.
A comparison of VOC contamination before and after one year of treatment revealed a 99.3% reduction
in saturated zone soils. Although no claims were made regarding expected percent reductions in the
saturated zone, the reduction that was achieved was comparable to those observed in the vadose zone
horizons.
Soil sampling conducted during Pre-treatment and Post-treatment events did not reveal any compounds
present at concentrations that might inhibit biodegradation (i.e., heavy metals). In addition, general soil
analyses revealed that there were sufficient quantities of soil nutrients available to biodegrade the entire
mass of contamination in the vadose zone of the treatment plot.
Bimonthly monitoring of the extracted air stream indicates that mass removal rates of VOCs were
highest at the beginning of the treatment when soil VOC concentrations were elevated and transfer to
the vapor phase occurred easily. As the concentration in the soil decreased, mass removal rates also
decreased and stabilized in spite of elevated flow rates. Vapor flow rates observed during the
Demonstration fall within the range of conventional SVE systems that rely solely on vapor extraction
as the primary mechanism for contaminant removal. The SWS® also exhibited the same pattern
observed in conventional SVE systems, which is characterized by high removal rates during the initial
operation of the unit, followed by an asymptotic decrease in removal rates.
The results of three system shut-down tests indicate that biodegradation was occurring across the
treatment plot, especially along the southern portion of the treatment plot where the highest levels of soil
contamination were measured. The correlation between high biological activity and contaminant
occurrence suggests that the technology was able to stimulate biodegradation of contaminants. The
results of three shut-down tests suggest a progressive decrease in biological activity over time. The
decrease in the rate of biodegradation, however, was significantly less than the rate of decrease of vapor
phase contaminants in the vacuum extraction line. This observation would support the developer's claim
that biological processes play an increasingly important role, relative to vapor extraction, as the
remediation proceeds.
The performance of the Biological Emission Control (BEC)* system could not be evaluated since it was
taken off-line a few months into the Demonstration when the exhaust off-gasses met the discharge
criteria for the site.
The system was initially installed and operated in a large portion of the site not impacted by dry well
contamination. Subsequent to this discovery, the system operation was shifted to that portion of the
treatment plot containing subsurface contamination. The fact that a major portion of the system was
installed over an uncontaminated area did not affect overall system performance; however, it did have
some impact on cost.
The cost for a full-scale remediation of soils at the Electro-Voice site, assuming that the total volume of
contaminated soil to be remediated is 21,300 yd3, is $220,737 or $10.36/yd3. The largest cost
component of the technology appears to be site preparation (28%), followed by analytical services (27%)
and residuals/waste shipping, handling and storage (13%).
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The following sections of this report contain the detailed information which supports the items
summarized in this Executive Summary.
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SECTION 1
INTRODUCTION
This section provides background information about the Superfund Innovative Technology Evaluation
(SITE) Program, discusses the purpose of this Innovative Technology Evaluation Report (ITER), and describes
the SWS® process. For additional information about the SITE Program, this technology, and the demonstration
site, key contacts are listed at the end of this section.
1.1 Background
The Subsurface Volatilization Ventilation System (SWS)® was developed by Billings and Associates,
Inc. (BAI) in response to the increasing demand for integrated remedial systems, that address all phases of
contamination problem in a faster, more effective, and less costly way than conventional remedial approaches.
The SWS® is of particular interest because it promotes the in-situ destruction of volatile organic compounds
(VOCs) by biodegradation and vapor extraction, reducing all phases of subsurface VOC mass without producing
toxic by-products. Air circulation provides indigenous soil microbes with the oxygen required to complete the
biochemical reactions that break down organic contaminants to harmless by-products (typically carbon dioxide
and water), in the liquid, aqueous, sorbed and vapor phases, hi addition, the continuous circulation of clean air
encourages the mass transfer of VOCs to the vapor phase, which is withdrawn from the subsurface by a network
of vacuum extraction wells, and is then treated above ground and released to the atmosphere.
Environmental Improvement Technologies, Inc. (EIT) holds the patents for the SWS®. In 1993, EIT
received two patents, and a continuation -in -part, for their technology, indicating that a third patent was in the
pipeline. BAI and B&RE acquired the rights to market the technology under a licensing agreement with EIT.
The SWS® has been implemented at 70 sites in New Mexico, North Carolina, South Carolina, Florida,
Minnesota, West Virginia, Illinois, Michigan, Pennsylvania, Texas and England. In 1991, the technology was
accepted into the Superfund Innovative Technology Evaluation Program (SITE) to undergo a performance
evaluation at the Electro-Voice facility in Buchanan, Michigan.
The Electro-Voice, Inc. (EV) facility is an active business located at 600 Cecil Street in the City of*
Buchanan, Berrien County, Michigan. EV manufactures audio equipment and has been in operation at its present
location since 1946. In February 1983, the facility was placed on the Michigan Act 307 and the Federal National
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Priority List as a result of detectable concentrations of cyanide, xylenes, and toluene found in on-site monitoring
wells. The groundwater contamination was originally attributed to the facility's two former wastewater lagoons.
The facility has recently been the focus of an extensive remedial investigation/feasibility study (RI/FS), initiated
shortly after EV and the U.S. Environmental Protection Agency (EPA) entered into an Administrative Order of
Consent (AO) on October 8, 1987 (effective October 15, 1987). Studies initiated under the RI revealed the
presence of organic and inorganic contaminants in soil and groundwater associated with a former fuel tank area
and the former dry well area. The soils of the dry well area have been identified as the principal source of
groundwater contamination, both on- and off-site. As per the Record of Decision (ROD), the dry well area is
included in the first operable unit remedial action for the EV site; the specified remedial action for the dry well
area is SVE followed by excavation, solidification and landfarming of any residuals. The dry well area was also
selected as the location for the USEPA SITE demonstration. The SWS* was implemented and operated at the
dry well area for a period of one year to evaluate the effectiveness of the technology for remediating subsurface
organic contamination, to provide justification for the execution of an Explanation of Significant Difference
(BSD) to the ROD for Operable Unit Number One.
1.2 Brief Description of Program and Reports
The SITE program is a formal program established by EPA's Office of Solid Waste and Emergency
Response (OSWER) and Office of Research and Development (ORD) in response to the Superfund Amendments
and Reauthorization Act of 1986 (SARA). The SITE program promotes the development, demonstration, and
use of new or innovative technologies to clean up Superfund sites across the country.
The SITE program's primary purpose is to maximize the use of alternatives in cleaning hazardous waste
sites by encouraging the development and demonstration of new, innovative treatment and monitoring
technologies. It consists of four major elements discussed below:
• the Emerging Technology Program,
• the Demonstration Program,
• the Monitoring and Measuring Technologies Program, and
• the Technology Transfer Program.
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The Emerging Technology Program focuses on conceptually proven bench-scale technologies that are
in an early stage of development involving pilot or laboratory testing. Successful technologies are encouraged
to advance to the Demonstration Program.
The Demonstration Program develops reliable performance and cost data on innovative technologies so
that potential users may assess the technology's site-specific applicability. Technologies evaluated are either
currently available or close to being available for remediation of Superfund sites. SITE demonstrations are
conducted on hazardous waste sites under conditions that closely simulate full-scale remediation conditions, thus
assuring the usefulness and reliability of information collected. Data collected are used to assess: (1) the
performance of the technology, (2) the potential need for pre- and post-treatment processing of wastes, (3)
potential operating problems, and (4) the approximate costs. The demonstrations also allow for evaluation of
long-term risks and operating and maintenance costs.
Existing technologies that improve field monitoring and site characterizations are identified in the
Monitoring and Measurement Technologies Program. New technologies that provide faster, more cost-effective
contamination and site assessment data are supported by this program. The Monitoring and Measurement
Technologies Program also formulates the protocols and standard operating procedures for demonstrating
methods and equipment.
The Technology Transfer Program disseminates technical information on innovative technologies in the
Emerging Technology Program, Demonstration Program, and Monitoring and Measurement Technologies
Programs through various activities. These activities increase the awareness and promote the use of innovative
technologies for assessment and remediation at Superfund sites. The goal of technology transfer activities is to
develop interactive communication among individuals requiring up-to-date technical information.
1.3 The SITE Demonstration Program
Technologies are selected for the SITE Demonstration Program through annual requests for proposals.
ORD staff review the proposals to determine which technologies show the most promise for use at Superfund
sites. Technologies chosen must be at the pilot- or full-scale stage, must be innovative, and must have some
advantage over existing technologies. Mobile and in-situ technologies are of particular interest.
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Once EPA has accepted a proposal, cooperative agreements between EPA and the developer establish
responsibilities for conducting the demonstrations and evaluating the technology. The developer is responsible
for demonstrating the technology at the selected site and is expected to pay any costs for transport, operations,
and removal of the equipment. EPA is responsible for project planning, sampling and analysis, quality assurance
and quality control, preparing reports, disseminating information, and transporting and disposing of treated waste
materials.
The results of this evaluation of the SWS* vapor extraction\air sparging and in-situ bioremediation
technology are published in two basic documents: the SITE Technology Capsule and this Innovative Technology
Evaluation Report. The SITE Technology Capsule provides relevant information on the technology, emphasizing
key features of the results of the SITE field demonstration. A Technology Evaluation Report (TER) is available
as a supporting document to the ITER. Both the SITE technology capsule and the ITER are intended for use by
remedial managers making a detailed evaluation of the technology for a specific site and waste.
1.4 Purpose of the Innovative Technology Evaluation Report (ITER)
This ITER provides information on the SWS* vapor extraction/in-situ bioremediation technology and
includes a comprehensive description of the demonstration and its results. The ITER is intended for use by EPA
remedial project managers, EPA on-scene coordinators, contractors, and other decision makers in implementing
specific remedial actions. The ITER is designed to aid decision makers in further evaluating specific technologies
for consideration as applicable options in a particular cleanup operation. This report represents a critical step
in the development and commercialization of a treatment technology.
To encourage the general use of demonstrated technologies, EPA provides information regarding the
applicability of each technology to specific sites and wastes. The ITER includes information on cost and
performance, particularly as evaluated during the demonstration. It also discusses advantages, disadvantages,
and limitations of the technology.
Each SITE demonstration evaluates the performance of a technology in treating a specific waste. The
waste characteristics of other sites may differ from the characteristics of the treated waste. Therefore, a
successful field demonstration of a technology at one site does not necessarily ensure that it will be applicable
at other sites. Data from the field demonstration may require extrapolation for estimating the operating ranges
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in which the technology will perform satisfactorily. Only limited conclusions can be drawn from a single field
demonstration.
1.5 Technology Description
The SWS® is an in-situ vacuum extraction/air sparging and bioremediation process designed to treat
all phases of organic contamination in soil and groundwater. The technology promotes in-situ remediation
through the injection of clean air into the saturated zone and the extraction of vapor phase contaminants in the
vadose zone. This induced circulation of air in the subsurface encourages the mass transfer of VOC contaminants
present as bulk liquid, dissolved and sorbed forms to a gas phase which is then extracted from the ground. The
subsurface air circulation effectively oxygenates vadose zone soils, thereby stimulating aerobic microbiological
processes which degrade organic contaminants. Vapor extraction removes the easily-strippable volatile
components from the soil and/or groundwater and tends to be the dominant mechanism during the early phases
of system operation. Bioremediation processes dominate the later phases of the application. Using the
combination of vapor extraction and biostimulation is faster than the use of biostimulation alone, and reduces
the amounts of volatile organics in the exhaust gasses than vapor extraction alone. Although the developer claims
that more volatiles are mobilized because of vertically flowing air that strips more than just vadose zone soils,
much of the mobilized mass is converted to biologically produced carbon dioxide.
The SWS® process consists of a network of injection and vacuum extraction wells plumbed to one or
more compressors and vacuum pumps, respectively. The vacuum pumps create the negative pressure necessary
to extract contaminant vapors. The air compressors simultaneously create positive pressures across the treatment
area to deliver the oxygen needed to enhance aerobic biodegradatioa The system is maintained at a vapor control
unit (VCU) that houses the pumps, compressors, control valves, gauges and other process control hardware. Each
SWS* process is custom-designed to meet specific site conditions. The number and spacing of the wells
depends upon the physical, chemical and biological characteristics of the site, as well the results of a matrix-
model. Depending on site conditions, subsurface vaporization can be enhanced via the injection of heated air.
In addition, separate valves may be installed at the manifold of individual reactor lines, or on individual well
points, for better control of air flow and pressures in the treatment area. Depending on groundwater depths and
fluctuations, horizontal vacuum screens, "stubbed" screens, or multiple-depth completions can be applied. The
system designed for each site is dynamic, allowing positive and negative air flow to be shifted to different
locations in the subsurface to focus and concentrate remedial stresses on specific areas. Negative pressure is
maintained at a suitable level to prevent the escape of vapors from the treatment area. If air quality permits
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require emission control, the developer claims that the system's vacuum extraction exhaust vapors can be treated
by the BECs® using the site's indigenous microbes.
1.6 Key Contacts
Additional information on the SWS* soil remediation technology and the SITE program can be obtained
from the following sources:
The SWS* Vapor Extraction/Air Sparging and In-Situ Bioremediation Technology
Steve Thompson Mr. Jeff Billings
Project Manager President
Brown & Root Environmental Environmental Improvement Technologies, Inc.
4641 Willoughby Road Billings and Associates, Inc.
Holt, Michigan 48842 3816 Academy Parkway, N-NE
517-694-6200 Albuquerque, New Mexico 87109
505-345-1116
The SITE Program
Mr. Robert A. Olexsey, Director Mr. John Martin
Superfund Technology Demonstration Division EPA SITE Technical Project Manager
U.S. Environmental Protection Agency U.S. Environmental Protection Agency
26 West Martin Luther King Drive 26 West Martin Luther King Drive
Cincinnati, Ohio 45268 Cincinnati, Ohio 45268
Phone: 513/569-7328 Phone: 513/569-7758
Fax: 513/569-7620 Fax: 513/569-7620
Information on the SITE program is available through the following on-line information clearinghouses:
• The Alternative Treatment Technology Information Center (ATTIC) System (operator: 703-
908-2137; access: 703-908-2138) is a comprehensive, automated information retrieval system
that integrates data on hazardous waste treatment technologies into a centralized, searchable
source. This data base provides summarized information on innovative treatment technologies.
• The Vendor Information System for Innovative Treatment Technologies (VISITT) (Hotline:
800-245-4505; Fax: 513-891-6685) database contains information on 231 technologies offered
by 141 developers.
• The OSWER CLU-In electronic bulletin board contains information on the status of SITE
technology demonstrations (Operator: 301-589-8368; Access: 301-589-8366).
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Technical reports may be obtained by contacting the Center for Environmental Research Information (CERI),
26 Martin Luther King Drive in Cincinnati, OH 45268 at 513/569-7562.
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SECTION 2
TECHNOLOGY APPLICATIONS ANALYSIS
This section of the report addresses the general applicability of the SWS* vapor extraction /air sparging
and in-situ bioremediation technology to contaminated waste sites. The analysis is based on the SITE
demonstration results, and conclusions are based exclusively on these data since only limited information is
available on other applications of the technology. The SITE Demonstration was conducted on approximately
2,300 cubic yards of soil, of which an estimated 800 cubic yards were contaminated with varying levels of
benzene, ethylbenzene, toluene, xylenes, trichloroethene, tetrachloroethene and 1,1-dichloroethene.
2.1 Key Features
The unique feature of the SWS* process is the integration and optimization of vapor extraction/air
sparging and biostimulation principles for the in-situ treatment of subsurface organic contamination. The vapor
extraction component destroys the easily-strippable VOC contaminants while the bioremediation component
attacks the less volatile, more recalcitrant organics. The SWS* process can be used to remediate all phases
(liquid, dissolved, sorbed, and vapor phases) of VOC contamination in soils and groundwater. As a result, the
integrated SWS* process can treat contaminants that would normally not be remediated by vapor extraction
alone (such as chemicals with lower volatility and/or chemicals that are tightly sorbed). Using the combination
of vapor extraction and biostimulation is faster than the use of biostimulation alone, and reduces the amounts of
volatile organics in the exhaust gasses that would be produced if vapor extraction was used alone. Unlike vapor
extraction/air stripping technologies that often require off-gas treatment to ensure that emissions meet air quality
standards, the SWS* limits the need for costly and space-consuming above-ground treatment (i.e., activated
carbon or catalytic oxidation) of the extracted air stream. According to the developer, extracted vapors may need
to be treated during the early stages of SWS* implementation, when the overall rate of mass transfer of
contamination to the vapor phase exceeds the biodegradation rate. Eventually, as biodegradation rates surpass
the net rate of contaminant transfer to the vapor phase, above-ground treatment of the extracted air stream is no
longer needed At this point vapor extraction off-gas will consist predominantly of carbon dioxide, a by-product
of aerobic biodegradation. This reduced need for extracted air stream treatment during site remediation is
reflected in decreased capital and operating costs. The SWS* also employs the use of BAI's biofiltration system
(BECs)* for the treatment of extracted vapors that further reduces the space requirements and costs associated
with conventional vapor treatment technologies.
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2.2 Operability of the Technology
The SWS® uses a network of injection and extraction wells designed to circulate air below the ground
to facilitate the volatilization and removal of VOCs from the soil and groundwater, as well as to provide the
oxygen necessary to enhance the rate of aerobic biodegradation of organics by indigenous soil microbes. Air
injection wells are installed below the groundwater table and vacuum extraction wells are installed above the
water table. The exact depth and screened intervals of these wells are site specific design considerations. A
typical SWS® consists of alternating air injection and vacuum extraction wells aligned in rows referred to as
"reactor lines". The reactor lines are linked together and plumbed to one or more compressors or vacuum pumps.
The vacuum pumps create the negative pressure to extract contaminant vapors, while the air compressors
simultaneously create positive pressures across the treatment area, to deliver oxygen for enhanced aerobic
biodegradation. The system is maintained at a Vapor Control Unit (VCU) that houses pumps, control valves,
gauges and other process control hardware. Each SWS* is custom-designed to meet specific site conditions.
The number and spacing of the wells depends upon the modeling results of applying a design parameter matrix,
as well as the physical, chemical and biological characteristics of the site. The SWS* design allows for flexibility
in terms of system expansion and operation. Because of the simplicity of system construction, and the reserve
capacity of air injection and vapor extraction built into a typical design, the cost of expansion (e.g., additional
wells and reactor lines) would normally be no greater than 10% to 20% of the total project budget.. Details
concerning the design of the SWS* evaluated under the SITE Demonstration Program are presented in Section
4.2.
The SWS* is a relatively simple system. Once installed, the technology requires only occasional
maintenance and operator attention. Actual system operation requires extensive training and experience. If
needed, the SWS* can incorporate its exclusive biofilters, known as Biological Emission Control (BEC*
devices, to reduce the levels of VOCs in the extracted air stream in order to meet air quality standards. These
devices are often taken off-line once the rate of biodegradation exceeds the net rate of transfer of contaminant
mass into the circulating air. The BEC* units were used at the beginning of the SITE Demonstration, but were
taken out of service once the vacuum extraction exhaust gas met the discharge criteria that had been established
with the state for discharge to the atmosphere.
Air flow management is the most important of the operating parameters that influence the performance
of the SWS* remediation technology. Air flow adjustments are made to enhance subsurface conditions that
stimulate the activity of the microbial populations responsible for the biodegradation of organic contaminants.
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Air flow management is achieved at the Vapor Control Unit, or in some cases at each well head, through
adjustment of control valves. This configuration allows optimal control of air input and vacuum rates, such that
positive and negative air flow can be shifted to different locations of the treatment plot to concentrate remedial
stress on the areas requiring it most. If a portion of the site is responding slowly, more remedial stress is applied
through a series of valve adjustments. Conversely, less stress may be directed to portions of the site that are
responding more rapidly, or have already been cleaned up to regulatory standards. Negative pressure is
maintained at a suitable level to prevent escape of vapors.
The presence of indigenous microbes that utilize the organic contaminants as a food source is another
potential operating parameter. Although not often necessary, periodic assessments of microbial activity and
biotransformation capacities might be conducted. These assessments are determined through microbial assays,
estimations of nutrient requirements, shut down testing and system-specific C02 data as follows:
• Microbial Populations: Depth-specific soil samples are collected over the course of the
remediation to profile changes in the microbial populations resulting from system operation.
Standard plate count methodologies are employed in the enumerations. Samples should be
collected from areas containing significant contamination since it is in these areas that the
presence of microbes is most important. According to the developer, these measures are no
longer considered necessary when dealing with fuel related contamination because microbes
have been found on all fuel sites, under many soil conditions.
• Nutrient Requirements: A baseline evaluation of the nutrient requirements necessary to sustain
bacterial viability and growth might also be performed. The total mass of contamination within
the area being treated is estimated, as well as that portion which is considered biodegradable.
Based upon these mass estimates, the amounts of nitrogen and phosphorus needed by
indigenous soil microbes to synthesize enough cell material to completely metabolize the total
mass of contamination is calculated. These requirements are then compared to actual mass of
nutrients available in the matrix. If insufficient nutrients are available, nutrient addition might
be necessary to optimize the viability and activity of the soil microbes. According to the
developer, these nutrient additions are seldom required.
• Bioremediation Rate: In-situ respiration or "shut-down" testing might be performed periodically
to assess the progress of subsurface microbial activity. The magnitude of microbial activity is
directly proportional to the rate of oxygen depletion. Ideally, the rate of oxygen depletion
should be greatest where increased concentrations of degradable organic compounds are present.
• C02 Production: CO2 measured at the vacuum extraction well heads as well as at the combined
vapor extraction line, can provide information on microbial activity over the course of
remediation, although it tends to be a less reliable indicator than 02. An increase in C02 at these
locations can be correlated to an increase in the biodegradation rates.
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The types and phases of contaminants present also affect the performance of the SWS* Contaminants
that are highly volatile are more amenable to vapor extraction, while less volatile contaminants respond best to
biodegradation. Halogenated aliphatic compounds containing more than two halogens in their molecular structure
are not particularly susceptible to biodegradation, but might be broken down into harmless end products in the
presence of the less volatile degradable compounds via cometabolism. On the other hand, more tightly sorbed
and less soluble compounds result in slower mass transfer and bioremediation rates.
Temperature also plays a key role in system performance. The rate of in-situ biodegradation and mass
transfer of contaminants to the vapor phase is controlled in large part by temperature. The literature shows that
metabolic reactions tend to occur rapidly under warmer conditions and considerably more slowly under cooler
conditions. Contaminant vapor concentrations are dependent on temperature; therefore, removal rates are
strongly influenced by subsurface temperatures. Most in-situ temperatures are warm enough to provide adequate
rates of hydrocarbon biodegradation. Due to the relatively high thermal mass of soils and soil moisture and the
low thermal mass of injection air, a great deal of operational time is required to cause a significant temperature
change. During the winter months in northern climates, it is not uncommon for the SWS* to inject heated au-
to prevent a decrease in groundwater temperatures. Solar panels may be used for this purpose, or the pumps can
be located within a heated building and the relatively warm air from the building can be injected into the ground.
The VCU is also heated to increase longevity of the pumps, decrease condensate freezing problems, and maintain
a hospitable environment for the microbes in the BEC® units.
Soil pH can affect biodegradation. Ideally the pH should be within the range of 5.5 to 8.5 S.U. which
is within the acceptable biological treatment range. Soils with higher and lower pHs might require adjustment
prior to the implementation of the technology. This can be problematic with alkaline soils which are known for
their large buffering capacity. Fortunately, pH adjustment is rarely necessary, since the indigenous microbes are
typically adapted to the natural values found in the soil.
Soil permeability and stratification at a site influence the operational performance of the system by
controlling air flow pathways. At a highly stratified site, characterized by multiple geological horizons each with
its own unique soil permeability, injected air will generally follow the course of least resistance and tend to travel
laterally in coarser strata, potentially bypassing the target contaminations area. This lateral migration could also
result in the spread of subsurface contamination as contaminant stripped from the groundwater and lower vadose
zone travels laterally along the soil/water interface. If a site is highly stratified, sand chimneys are typically
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installed to enhance vertical air circulation. Sand chimneys are sand-packed borings which provide passive
airflow between the subsurface layers, increasing both soil vapor extraction and biodegradation rates.
Local air quality standards might alter the operation and configuration of the SWS*. During the early
stages of SWS® implementation the overall rate of mass transfer of contamination to the vapor phase, may
exceed biodegradation rates. During this time, extracted vapors might require treatment before being released
to the atmosphere. Off-gas extracted from the vacuum extraction wells can be routed through a configuration
of Biological Emission Control (BEC)® units, which according to the developer, can achieve up to 80%
reductions in VOC stack emissions, at approximately 20% of the traditional emission costs. The exhaust from
the BEC® units may also be polished by vapor phase activated carbon, or catalytic oxidation to achieve near 100%
VOC removal, if required. Vacuum extraction emissions can also be controlled within regulatory limits by
adjusting the air injection and vacuum extraction rates.
2.3 Applicable Wastes
The SWS* process is suitable for the in-situ treatment of soil, sludges and groundwater contaminated
with gasoline, diesel fuels, and other hydrocarbons, including halogenated compounds. The medium to be treated
must not possess levels of toxic metals or any other compound that may be detrimental to the indigenous soil
microbes. Although high levels of organic contamination, or disproportionately higher levels of halogenated
VOCs over non-halogenated VOCs, may inhibit the performance of the microorganisms, the vapor extraction
component of the SWS* process will eventually reduce the levels of these compounds to concentrations more
suitable for biodegradation. Halogenated aliphatic compounds containing more than two halogens can be
transformed to harmless end-products during or following the metabolism of natural substrates. The developer
claims that the SWS* works effectively on benzene, toluene, ethylbenzene, and xylene (BTEX) contamination.
The technology should be effective in treating soils and groundwater contaminated with virtually any material
that exhibits volatility or is biodegradable. By changing the injected gases, anaerobic conditions can be developed
and a microbial population can be used to remove nitrate from groundwater. The aerobic SWS* can also be
used to treat heavy metals in groundwater by raising the redox potential of the groundwater and precipitating the
heavy metals.
In order for the bioremediation component of the system to be effective, prolific indigenous microbial
populations must be present in the contaminated matrix. In rare situations where the microbial population is less
prolific than is needed for the job, the indigenous communities can be augmented through the BioTrans™
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technique. The process involves the isolation of dominant indigenous strains of hydrocarbon-degrading microbes
obtained from soils or groundwater samples collected from biologically-active parts of the site. These strains are
then cultivated until sufficient populations are produced, and the less biologically active portions of the site are
then inoculated with the cultivated microbes. This technique was not used in the Demonstration, because suitable
populations of indigenous microbes were already present.
2.4 Availability and Transportability of the Equipment
The SWS® is an in-situ remediation technology that is installed in-place and custom-designed to meet
specific site conditions. For the most part, the technology is not considered mobile or transportable, although
the developer has used a trailer mounted VCU for small sites and emergency response situations. Most of the
hardware components used to construct and operate the system are common and readily available. Many of the
components can be obtained at a hardware or plumbing supply store, and can be transported to the site by car or
pickup truck.
System installation can take anywhere from a week to a month. The time it takes to install an SWS*
largely depends on the number and depth of the injection and vacuum extraction wells. Installation requires a
drill rig and a trained drill crew. Hollow-stem augering techniques are typically employed. A trenching device
is also required for the horizontal installations of vacuum extraction and injection lines.
System demobilization activities consist of disconnecting utilities, and disassembling equipment housed
in the VCU and transporting it off-site. Vacuum extraction and injection wells are either left in place as part of
a facility's environmental monitoring program or are abandoned in accordance with state and local standards.
Well abandonment will extend the length of time needed to demobilize a site.
2.5 Materials Handling Requirements
The materials handling requirements for the SWS* process are quite limited since the process is carried
out "in-situ" For the most part, materials handling is only an issue during system installation. During
installation, contaminated soil cuttings may be generated as a consequence of drilling and trenching activities.
These cuttings typically require staging or storage in containers, such as 5 5-gallon steel drums or roll-off boxe§,
until arrangements can be made to dispose of them according to regulatory criteria. Materials handling during
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system installation can involve drill rigs, front-end loaders, backhoes and trenching equipment. The remediation
area should be well graded and accessible to heavy equipment.
Sampling of soil before, during and after treatment may also require the use of materials handling
equipment. Soil samples will be required to document that the regulatory cleanup criteria have been met, as well
as to monitor microbial activity and biotransformation capacities. Soil sampling will likely require the use of a
drill rig, a shovel or another device depending on the characteristics of the soil and the depths to be sampled.
Full-scale remediation of a site using SWS* generally includes an appropriately-sized configuration of
BEC® units to remove vapor phase contaminants from the vacuum extraction off-gas before release to the
atmosphere. According to the developer, the BECs* can also be used to treat condensate, well drilling wash
water, cuttings and the ditching material to at least reduce the volume and off-site costs. Since the BEC® units
were used only briefly during the Demonstration, however, no conclusions could be drawn about their
effectiveness. Vacuum extraction emissions may also be controlled within regulatory limits by adjusting the air
injection and vacuum extraction rates. Special handling requirements might be required if activated carbon is
needed for additional polishing of the off-gas. Appropriate arrangements will need to be made to store, regenerate
and dispose of this material.
2.6 Site Support Requirements
Technology support requirements include utilities, support facilities, and support equipment. These
requirements are discussed below.
The major utility required to operate the SWS* is electricity. 110 and 220 volt electrical hookups are
required in the Vapor Control Unit (VCU). The 220 volt line is needed to power the injection air heater. The 110
volt line is needed to power the air compressors and vacuum pumps. These electrical services are commonly
available, but might require a power drop to bring the electricity to the VCU. If power is unavailable and a
connection to the power grid is considered unfeasible, diesel generators could be used.
Minor utility needs include a potable water supply, telephone and sewer service. Potable water is
necessary for equipment decontamination and personnel needs. If potable water is unavailable, it can be trucked
in. Phone service to the site is useful for general communication and for summoning emergency assistance. If
a sewer hook up is not available, portable toilets can be used for sanitary purposes.
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Support facilities required by the SWS® process include an enclosed heated area for housing pumps,
control valves, gauges, emission control equipment, and other process hardware. This enclosed area is the
system's Vapor Control Unit (VCU) where operational control of the SWS® is maintained. If a facility lacks
the capacity to house these items, a temporary structure of sufficient size must be constructed to serve this
purpose. The VCU must be heated to minimize climate-related problems with the equipment. Auxiliary
buildings might be needed for storage of supplies and tools. A roll-off or drum staging area will be required for
the temporary storage of drill cuttings generated during system installation.
Access to the site must be provided over roads suitable for travel by heavy equipment. Personnel must
also be able to reach the site without difficulty. Depending on site location, security measures might be necessary
to protect the public from accidental exposures and to prevent accidental and intentional damage to the
equipment. A chain-link fence with a locking gate large enough to allow trucks to enter and leave should provide
adequate security.
Support equipment needed during system installation and demobilization will likely include drill rigs and
trenchers, and may involve earth moving equipment, forklifts, containers for storing drill cuttings and containers
for waste water. Earth moving equipment, including backhoes and/or front-end loaders, will be needed for
trenching and transferring drill cuttings to a roll-off or to drums, and, if necessary, regrading the site. A forklift
or handtruck might be necessary for moving drums and supplies around the site. Support equipment needed
during system operation should consist only of emission control devices. A configuration of BEC* units (possibly
coupled with vapor phase activated carbon or catalytic oxidation systems) might be required during the early
phases of SWS* operation.
2.7 Ranges of Suitable Site Characteristics
Generally, SWS® is applicable and effective over a wide range of site characteristics. The site
characteristics described in this section provide additional information about items which require consideration
before applying the technology.
A candidate site must be well graded and accessible to drill rigs and other heavy equipment such as front-
end loaders, backhoes, fork lifts, and trenching equipment. The subsurface should be free of utility lines or other
underground facilities (i.e., fuel tanks). The subsurface should be free of large debris, such as might be found
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in a landfill. The contaminant plume should be accessible to allow the installation of an S WS* that provides
adequate coverage of the plume.
The size and shape of the SWS* treatment plot should be in accordance with the dimensions and pattern
of subsurface contamination as adjusted for permeability distribution, surface structures and contaminant phase.
Typically, the network of vacuum extraction and injection wells are positioned directly over contaminated areas,
therefore, these areas need to be accessible. Some of these problems can be overcome by using directional and
horizontal drilling techniques for well emplacement. The site should provide additional space for the VCU
structure and the drum staging or roll-off storage area. The VCU requires about 150 square feet. If a roll-off
is utilized, sufficient area will be required to maneuver the roll-off in and out of the site. There should also be
room for a waste water storage tank and a tank truck if potable water needs to be trucked in. A 20-square-foot
decontamination area will need to be positioned so as to facilitate the decontamination of equipment and
personnel during system installation and demobilization.
Soil characteristics at a particular site are instrumental in determining the site's suitability for the SWS*.
Relatively homogeneous fairly coarse soils are generally conducive to uniform as well as rapid contaminant
reductions. Vertical variations in permeability, as is the case with highly stratified soils, may have a tendency
to induce air to flow along horizontal pathways increasing the risk for contamination to spread laterally.
Horizontal air flow can be controlled by a number of strategically placed sand chimneys. Sand chimneys, which
are essentially sand/gravel filled boreholes, provide a vertical conduit for air flow and enhance air flow
communication between all layers. Low soil permeabilities limit subsurface airflow rates and can reduce overall
process efficiency. According to the developer, SWS® systems have been operated with success down to
injection zone permeabilities of 10"6 cm/sec. Low permeability settings require special design considerations and
operational methods, but do not necessarily negate SWS* success. Unlike some bioventing technologies,
SWS* does not seem to be affected by low soil moisture since the air moving vertically from below the water
table has a high humidity value.
Ideally, water tables should be more than several feet from the land surface, so as not to limit the
effectiveness of vapor extraction and bioremediation as a result of reduced air flow. Some designs have been
effective on sites with extremely shallow water tables by placing the vacuum lines above ground and covering
them. The pavement or concrete used to cover the site would increase installation costs.
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Soils with a high humic content could interfere with the application of SWS® by slowing down the
cleanup due to increased organic adsorption and oxygen demand. Soils possessing a high iron content could
produce deleterious geochemical reactions. (Induced precipitation caused by a change in the redox potential could
cause clogging of the aquifer.) The problem would manifest itself by causing a major decrease in flow rate of
injection and a synchronous increase in backpressure on the pumps. This problem would likely be limited only
to those sites with very high dissolved iron concentrations and adequate groundwater flow to supply the iron at
a rapid rate. The developer has yet to encounter such conditions, after applying the technology to over 70 site.
Since bioremediation is a major component of the SWS* technology, a site's soils should not contain
appreciable amounts of toxic metals or any other compound that may be detrimental to the indigenous soil
microbes. This has not been a problem to date with most fuel spill sites, but some of the larger hazardous waste
sites might pose some problems.
The technology can be operated in nearly every climate. Since soil is a good insulating material, most
in-situ temperatures are warm enough to provide adequate rates of hydrocarbon biodegradation even under colder
surface conditions. Equipment can be climatized to prevent damage due to hot or cold conditions.
The SWS® process can be used in fairly close proximity to inhabited areas, as long as appropriate
measures are taken to prevent off-site emissions, odors and noise. The SWS* produces little noise while
operating, and emissions are controlled by the BEC* units. Equipment must be transported to the site during
installation; however, once the SWS® is operational, there is little additional traffic generated by the site.
2.8 Limitations of the Technology
In the application of any in-situ air sparging technology, it is imperative that the overall site remediation
plan include a properly engineered soil vapor extraction (SVE) system to capture the contaminated vapors
emanating from the saturated zone. Since the potential exists for enhanced migration of contaminant vapors off-
site, the application of this technology is generally limited to sites where SVE is feasible. One possible exception
to the requirement of an accompanying SVE system is a situation where the overall remediation system design
relies on in-situ biodegradation to destroy the contaminant vapors in the vadose zone and vapor migration is not
a concern.
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The SWS* is generally not considered a mobile technology, although the developer occasionally
employs a trailer mounted VCU for small sites and emergency response situations. The technology has to be
installed and configured to address specific site problems. The installation is therefore intrusive and usually
involves considerable digging, trenching and drilling. The installation phase can take up to a month to install and
although the system components are simple, installation can be disruptive and noisy. During installation, workers
might be exposed to chemical hazards from coming in contact with contaminated material. Workers must be
advised of the chemical and physical hazards at the site and wear appropriate protective gear.
The effectiveness of SWS* is sensitive to soil air flow permeability. As discussed in the previous
section, relatively homogeneous fairly coarse soils are generally conducive to uniform as well as rapid
contaminant reductions. In highly stratified soils, air may travel far from the injection well along coarser strata
and never reach shallower portions of the vadose zone. Horizontal air flow and the potential lateral spread of
vapor phase contamination is typically stemmed by a number of strategically placed sand chimneys, also
discussed in the previous section.
In situations in which dense non-aqueous phase liquids (DNAPLs) are present, it is possible to spread
the immiscible phase and increase the size and concentrations of the VOC plume. This may actually be used to
advantage in a site remediation to mobilize residuals and, in conjunction with groundwater control, realize a more
efficient mass removal process.
SWS* may not be an economically beneficial alternative for remediation of materials of a very low
permeability, although the developer claims that the technology has been operated with success down to an
injection zone permeability of 10"* cm/sec. In rare situations, potential geochemical changes may be induced
through the application of the technology causing clogging of the aquifer. The potential for fouling may be
evaluated using available geochemical models, or avoided by using a more appropriate gaseous medium.
2.9 ARARS for the SWS* Technology
This subsection discusses specific federal environmental regulations pertinent to the operation of the
SWS* Vapor Extraction/In-Situ Bioremediation Technology including the transport, treatment, storage, and
disposal of wastes and treatment residuals. Federal and state applicable or relevant and appropriate requirements
(ARARs) are presented in Table 2-1. These regulations are reviewed with respect to the demonstration results.
State and local regulatory requirements, which may be more stringent, must also be addressed by remedial
25
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managers. ARARs include the following: (1) the Comprehensive Environmental Response, Compensation, and
Liability Act; (2) the Resource Conservation and Recovery Act; (3) the Clean Air Act; (4) the Safe Drinking
Water Act; (5) the Toxic Substances Control Act; and (6) the Occupational Safety and Health Administration
regulations. These six general ARARs are discussed below.
26
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Table 2-1. Federal and State Applicable and Relevant and Appropriate Requirements (ARARs) for the SWS®Technology
*&r PROCESS -',
;;;5' ACnvrrY -
'•^.,
&'*..:..: : :
Waste
characterization of
untreated wastes
Soil excavation
Waste processing
'„ * ARAR
' -x
RCRA: 40 CFR Part
261 ( or state
equivalent)
CAA: 40 CFR Part 50
(or state equivalent)
RCRA: 40 CFR Part
264 (or state
equivalent)
CAA: 40 CFR Part 50
(or state equivalent)
DESCRSTIONOF
K16ULATIGN
Standards that apply to
identification and
characterization of
wastes
Regulations governs
toxic pollutants, visible
emissions and
particulates
Standards that apply to
treatment of wastes in
a treatment facility
Regulation govern
toxic pollutants, visible
emissions and
particulates
GENERAL
APPLICABILITY
Chemical and physical
analyses must be
performed to determine
if waste is a hazardous
waste.
If excavation is
performed, emission of
volatile compounds or
dusts may occur.
When hazardous
wastes are treated,
there are requirements
for operations,
recordkeeping, and
contingency planning.
Stack gases may
contain volatile organic
compounds or other
regulated gases.
SPECIFIC
APPLICABILITY
T O SV?$*
Chemical and physical
properties of waste
determine its suitability
for treatment by
SVVS®
Applies to construction
activities (i.e., drilling
and trenching) during
system installation.
Applicable or
appropriate for SWS®
operations.
During SVVS®
operations, stack gases
must not exceed limits
set for the air district
of operation. Standards
for monitoring and
recordkeeping apply.
N>
~J
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Table 2-1. (Continued)
PROCESS
ACTIVITY
ARAR
DESCRIPTION OF
REGULATION
SPECIFIC
TO SV¥S*
Storage of auxiliary
wastes
RCRA: 40 CFR Part
264 Subpart J (or state
equivalent)
Regulation governs
standards for tanks at
treatment facilities
If storing non-RCRA
wastes, RCRA
requirements may still
be relevant and
appropriate
Storage tanks for liquid
wastes (e.g.,
decontamination waters
and condensate)must
be placarded
appropriately, have
secondary containment
and be inspected daily.
to
00
RCRA: 40 CFR Part
264 Subpart I (or state
equivalent)
Regulation cover
storage of waste
materials generated
Applicable for RCRA
wastes; relevant and
appropriate for non-
RCRA wastes
Roll-offs or drums
containing drill
cuttings need to be
labeled as hazardous
waste. The storage
area needs to be in
good condition, weekly
inspections are
required, and storage
should not exceed 90
days unless a storage
permit is obtained.
Determination of
cleanup standards
SARA: Section
121(d)(2)(ii); SDWA:
40 CFR Part 141
Standards that apply to
surface and
groundwater sources
that may be used as
drinking water
Remedial actions of
surface and
groundwater are
required to meet
MCLGs (or MCLs)
established under
SDWA
Applicable and
appropriate for S WS®
for projects that require
groundwater to be
treated.
-------
Table 2-1. (Continued)
«*^ PR0UJESS
INSCRIPTION OF
REGULATION
APPLICABILITY
SPECIFIC
APPLICABILITY
Waste disposal
RCRA: 40 CFR Part
262
Standards that pertain
to generators of
hazardous waste
Generators must
dispose of wastes at
facilities that are
permitted to handle the
waste. Generators must
obtain an EPA ID
number prior to waste
disposal.
Waste generated by the
the S WS is limited to
contaminated drill
cuttings. Spent
activated carbon could
be another waste if
carbon is used in the
treatment of system off
gases.
CWA: 40 CFR Parts
403 and/or 122 and
125
Standards for discharge
of wastewater to a
POTW or to a
navicable waterway
Discharge of
wastewaters to a
POTW must meet pre-
treatment standards;
discharges to a
navigable waterway
must be permitted
under NPDES.
Applicable and
appropriate for
decontamination
wastewaters and
condensate.
RCRA: 40 CFR Part
268
Standards regarding
land disposal of
hazardous wastes
Hazardous wastes must
meet specific treatment
standards prior to land
disposal, or must be
treated using specific
technologies.
Applicable for off-site
disposal of auxiliary
waste (e.g., drill
cuttings and other
waste soils).
-------
2.9.1 Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
The CERCLA of 1980 as amended by the Superfund Amendments and Reauthorization Act (SARA)
of 1986 provides for federal funding to respond to releases or potential releases of any hazardous substance into
the environment, as well as to releases of pollutants or contaminants that may present an imminent or significant
danger to public health and welfare or to the environment.
As part of the requirements of CERCLA, the EPA has prepared the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP) for hazardous substance response. The NCP is codified in Title
40 Code of Federal Regulations (CFR) Part 300, and delineates the methods and criteria used to determine the
appropriate extent of removal and cleanup for hazardous waste contamination.
SARA states a strong statutory preference for remedies that are highly reliable and provide long-term
protection and directs EPA to do the following:
• use remedial alternatives that permanently and significantly reduce the volume, toxicity, or
mobility of hazardous substances, pollutants, or contaminants;
• select remedial actions that protect human health and the environment, are cost-effective, and
involve permanent solutions and alternative treatment or resource recovery technologies to the
maximum extent possible; and
• avoid off-site transport and disposal of untreated hazardous substances or contaminated
materials when practicable treatment technologies exist [Section 121 (b)].
The SWS* process meets each of these requirements. Volume, toxicity and mobility of contaminants
in the waste matrix are all reduced as a result of treatment. Organic compounds are either stripped from
contaminated matrices to be biodegraded ex-situ in a configuration of biofilters or biodegraded in-situ by
indigenous soil microbes. In both cases, contaminants are subject to biochemical reactions that convert them to
cell material and energy for metabolic processes. The by-products of these reactions are innocuous and normally
consist of carbon dioxide and water. The need for off-site transportation and disposal of solid waste is eliminated
by in-situ treatment. Vacuum extraction off-gas may require treatment prior to release to the atmosphere.
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In general, two types of responses are possible under CERCLA: removal and remedial action. Superfund
removal actions are conducted in response to an immediate threat caused by a release of hazardous substances.
Removal action decisions are documented in an action memorandum. Many removals involve small quantities
of waste or immediate threats requiring quick action to alleviate the hazard. Remedial actions are governed by
the SARA amendments to CERCLA. As stated above, these amendments promote remedies that permanently
reduce the volume, toxicity, and mobility of hazardous substances, pollutants, or contaminants. The SWS*
process is likely to be part of a CERCLA remedial
action.
On-site remedial actions must comply with federal and more stringent state ARARs. ARARs are
determined on a site-by-site basis and may be waived under six conditions: (1) the action is an interim measure,
and the ARAR will be met at completion; (2) compliance with the ARAR would pose a greater risk to health and
the environment than noncompliance; (3) it is technically impracticable to meet the ARAR; (4) the standard of
performance of an ARAR can be met by an equivalent method; (5) a state ARAR has not been consistently
applied elsewhere; and (6) ARAR compliance would not provide a balance between the protection achieved at
a particular site and demands on the Superfund for other sites. These waiver options apply only to Superfund
actions taken on-site, and justification for the waiver must be clearly demonstrated.
2.9.2 Resource Conservation and Recovery Act (RCRA)
RCRA, an amendment to the Solid Waste Disposal Act (SWDA), is the primary federal legislation
governing hazardous waste activities and was passed in 1976 to address the problem of how to safely dispose
of municipal and industrial solid waste. Subtitle C of RCRA contains requirements for generation, transport,
treatment, storage, and disposal of hazardous waste, most of which are also applicable to CERCLA activities.
The Hazardous and Solid Waste Amendments (HSWA) of 1984 greatly expanded the scope and requirements
of RCRA.
RCRA regulations define hazardous wastes and regulate their transport, treatment, storage, and disposal.
If soils are determined to be hazardous according to RCRA (either because of a characteristic or a listing carried
by the waste), all RCRA requirements regarding the management and disposal of hazardous waste must be
addressed by the remedial managers. Criteria for identifying characteristic hazardous wastes are included in 40
CFR Part 261 Subpart C. Listed wastes from specific and nonspecific industrial sources, off-specification
products, spill cleanups, and other industrial sources are itemized in 40 CFR Part 261 Subpart D. For the
31
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Demonstration Test, the technology was subject to RCRA regulations because the Electro-Voice site is a
Superfund site contaminated with RCRA-listed wastes including benzene, ethylbenzene, toluene, xylenes,
trichloroetherie, 1,1-dichloroethene, and tetrachloroethene. RCRA regulations do not apply to sites where RCRA-
defined hazardous wastes are not present.
Unless they are specifically delisted through delisting procedures, hazardous wastes listed in 40 CFR Part
261 Subpart D remain listed wastes regardless of the treatment they may undergo and regardless of the final
contamination level in the streams and residues. This implies that even after remediation, "clean" wastes are still
classified as hazardous because the pre-treatment material was a listed waste.
For generation of any hazardous waste, the site responsible party must obtain an EPA identification
number. Other applicable RCRA requirements may include a Uniform Hazardous Waste Manifest (if the waste
is transported), restrictions on placing the waste in land disposal units, time limits on accumulating waste, and
permits for storing the waste.
Requirements for corrective action at RCRA-regulated facilities are provided in 40 CFR Part 264,
Subpart F (promulgated) and Subpart S (partially promulgated). These subparts also generally apply to
remediation at Superfund sites. Subparts F and S include requirements for initiating and conducting RCRA
corrective action, remediating groundwater, and ensuring that corrective actions comply with other environmental
regulations. Subpart S also details conditions under which particular RCRA requirements may be waived for
temporary treatment units operating at corrective action sites and provides information regarding requirements
for modifying permits to adequately describe the subject treatment unit.
2.9.3 Clean Air Act (CAA)
The CAA establishes national primary and secondary ambient air quality standards for sulfur oxides,
particulate matter, carbon monoxide, ozone, nitrogen dioxide, and lead. It also limits the emission of 189 listed
hazardous pollutants such as vinyl chloride, arsenic, asbestos and benzene. States are responsible for enforcing
the CAA. To assist in this, Air Quality Control Regions (AQCR) were established. Allowable emission limits
are determined by the AQCR, or its sub-unit, the Air Quality Management District (AQMD). These emission
limits are determined based on whether or not the region is currently within attainment for National Ambient Air
Quality Standards (NAAQS).
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The CAA requires that treatment, storage, and disposal facilities comply with primary and secondary
ambient air quality standards. Fugitive emissions from the SWS® technology may come from (1) excavation and
drilling activities related to system installation (volatile organic compounds or dust), (2) periodic sampling
efforts, (3) the staging and storing of contaminated drill cutting and (4) treated exhaust gas during system
operation. Soil moisture should be managed during system installation to prevent or minimize the impact from
fugitive emissions. State air quality standards may require additional measures to prevent fugitive emissions. The
off-gas treatment system must be adequately designed and air injection and vacuum extraction rates controlled
to meet current air quality standards. State air quality standards may require additional measures to prevent
emissions.
2.9.4 Clean Water Act (CWA)
The objective of the CWA is to restore and maintain the chemical, physical, and biological integrity of
the nation's waters. To achieve this objective, effluent limitations of toxic pollutant from point sources were
established. Publicly-owned treatments works (POTWs) can accept wastewaters with toxic pollutants; however
the facility discharging the waste water must meet pre-treatment standards and my need a discharge permit. A
facility desiring to discharge water to a navigable waterway must apply for a permit under the National Pollutant
Discharge Elimination System (NPDES). When an NPDES permit is issued, it includes waste discharge
requirements for volumes and contaminant concentration.
The only waste water produced by the SWS* process that might need to be managed is waste water
generated during equipment decontamination and condensate that accumulates in the air lines. Decontamination
water could amount to several thousand gallons depending on the level of effort involved to install a SWS*
Condensate should only be a fraction of this volume. Some of this water may be used as makeup water for the
BECs* during startup and system operation. Additional water that is generated and not utilized in the BECs* will
require analysis for the organic contaminants found in the site matrices that are targeted for treatment. Depending
on the levels of contaminants and the volume of this waste water, pretreatment might be required prior to
discharge to a POTW.
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2.9.5 Safe Drinking Water Act (SDWA)
The SDWA of 1974, as most recently amended by the Safe Drinking Water Amendments of 1986,
requires the EPA to establish regulations to protect human health from contaminants in drinking water. The
legislation authorized national drinking water standards and a joint federal-state system for ensuring compliance
with these standards.
The National Primary Drinking Water Standards are found in 40 CFR Parts 141 through 149. These
drinking water standards are expressed as maximum contaminant levels (MCLs) for some constituents, and
maximum contaminant level goals (MCLGs) for others. Under CERCLA (Section 121(d)(2)(A)(ii)), remedial
actions are required to meet the standards of the MCLGs when relevant. For the S WS* demonstration,
treatment of groundwater was a secondary objective but this may not hold true at other sites or during different
applications of the process.
2.9.6 Toxic Substances Control Act (TSCA)
The TSCA of 1976 grants the EPA authority to prohibit or control the manufacturing, importing,
processing, use, and disposal of any chemical substance that presents an unreasonable risk of injury to human
health or the environment. These regulations may be found in 40 CFR Part 761; Section 6(e) deals specifically
with PCBs. Materials with less than 50 ppm PCB are classified as non-PCB; those containing between 50 and
500 ppm are classified as PCB-contaminated; and those with 500 ppm PCB or greater are classified as PCB.
PCB-contaminated materials may be disposed of in TSCA-permitted landfills or destroyed by incineration at a
TSCA-approved incinerator; PCBs must be incinerated. Sites where spills of PCB-contaminated material or
PCBs have occurred after May 4,1987 must be addressed under the PCB Spill Cleanup Policy in 40 CFR Part
761, Subpart G. The policy establishes cleanup protocols for addressing such releases based upon the volume
and concentration of the spilled material. It has not been documented that the SWS* process is useful for PCB-
contaminated wastes to date.
2.9.7 Occupational Safety and Health Administration (OSHA) Requirements
CERCLA remedial actions and RCRA corrective actions must be performed in accordance with the
OSHA requirements detailed in 20 CFR Parts 1900 through 1926, especially §1910.120 which provides for the
health and safety of workers at hazardous waste sites. On-site construction activities at Superfund or RCRA
34
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corrective action sites must be performed in accordance with Part 1926 of OSHA, which describes safety and
health regulations for construction sites. State OSHA requirements, which may be significantly stricter than
federal standards, must also be met.
All technicians and subcontractors involved with the installation and operation of the SWS® Vapor
ExtractionMn-Situ Bioremediation system are required to have completed an OSHA training course and must be
familiar with all OSHA requirements relevant to hazardous waste sites. Workers on hazardous waste sites must
also be enrolled in a medical monitoring program. The elements of any acceptable program must include: (1) a
health history, (2) an initial exam before hazardous waste work starts to establish fitness for duty and a medical
baseline, (3) periodic examinations (usually annual) to determine whether changes due to exposure may have
occurred and to ensure continued fitness for the job, (4) appropriate medical examinations after a suspected or
known overexposure, and (5) an examination at termination.
For most sites, minimum PPE for workers will include gloves, hard hats, safety glasses, steel-toe boots,
and Tyvek®. Depending on contaminant types and concentrations, additional PPE may be required, including the
use of air purifying respirators or supplied air. Noise levels during the operation of the SWS* are not expected
to be high, except during the construction, which will involve the operation of heavy equipment. During these
activities, noise levels should be monitored to ensure that workers are not exposed to noise levels above a time-
weighted average of 85 decibels over an eight-hour day. If noise levels increase above this limit, workers will
be required to wear ear protection. The levels of noise anticipated are not expected to adversely affect the
community, depending on its proximity to the treatment site.
The SWS* VCU could be considered a confined space. Special consideration should be made during
the construction of the VCU to provide adequate ventilation. Otherwise workers will be required to comply with
the recently promulgated OSHA requirements for confined spaces (29 CFR § 1910.146), including requirements
for stand-by personnel, monitoring, placarding, and protective equipment. Since the installation of the SWS*
will require some excavation, trenches could be considered additional confined spaces (based on type and depth)
and the same requirements would have to be met. Other construction- or plant-related OSHA standards may also
apply while installing and operating a SWS*, including shoring of trenches, and lock-out/tag out procedures on
powered equipment.
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2.9.8 State Requirements
In many cases, state requirements supersede the corresponding Federal program, such as OSHA or
RCRA, when the state program is Federally approved and the requirements are more strict. The state of Michigan
had other regulatory requirements which are not covered under the major Federal Programs including special
requirements for operating on a floodplain.
36
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SECTIONS
ECONOMIC ANALYSIS
3.1 Introduction
This economic analysis is based on assumptions and costs provided by B&RE and on results and
experiences from the SITE demonstration operated over a 1-year period at the Electro-Voice site, located in
Buchanan, MI. The costs associated with treatment by the SWS* process, as presented in this economic analysis,
are defined by 12 cost categories that reflect typical cleanup activities performed at Superfund sites. Each of these
cleanup activities is defined and discussed; they form the basis for an estimated cost analysis of a full-scale
remediation at the same site.
The SWS® is applicable to sites contaminated with gasoline, diesel fuels, and other hydrocarbons,
including halogenated compounds. The technology can be applied to contaminated soils, sludges, free-phase
hydrocarbon product, and groundwater. The EV site included all of these. A number of factors could affect the
estimated cost of treatment. Among them, were: the type and concentration of contaminants, the extent of
contamination, groundwater depth, soil moisture, air permeability of the soil, site geology, geographic site
location, physical site conditions, site accessibility, required support facilities and availability of utilities, and
treatment goals. It is important to thoroughly and properly characterize the site before implementing this
technology, to insure that treatment is focused on contaminated areas. This cost may be substantial, but is not
included here. Even if the treated area is offset from the contaminated area, as was the case in the SITE
demonstration, the process is still effective in removing the contamination, showing that there is some flexibility
in applying this technology. However, there will probably be an associated increase in costs in terms of the length
of treatment required to achieve a certain cleanup level. Another key factor that may not be accurately predictable
without a pilot test is the radius of influence and, consequently, the number of wells needed to remediate a
particular site. The cost of conducting such a pilot study is also not included here.
The economic analysis for a full-scale remediation at this site was done as a base case, assuming that the
performance was similar to that demonstrated under the SITE program. Cost figures provided here are "order-of-
magnitude" estimates, and are generally +50%/-30%.
37
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3.2 Conclusions
• The cost to remediate 21,3 00 yd3 of vadose zone soils during a full-scale cleanup over a 3 -year
period at the Electro-Voice Superfund site in Buchanan, MI was estimated to be $220,737 or
$10/yd3, not including effluent treatment and disposal. The majority of this was incurred in the
first year, primarily due to site preparation.
• The largest cost component was Site Preparation (28%), followed by Analytical Services (27%),
and Residuals & Waste Shipping, Handling, and Storage (13%). These four categories
accounted for 68% of total costs. The next largest component was Labor (9%), indicating that
this technology is not labor-intensive, although travel, per diem, and rental car expenses were
not considered. Capital Equipment, and Utilities each accounted for 6% of costs, with the
remainder of the categories each accounting for 5% or less.
• If Effluent Treatment and Disposal costs had been included, this would have added $164,500
to the first year of remediation and brought the total cleanup figure to $385,237 ($ 18.09/yd3).
This would have accounted for over 43% of the total cleanup cost.
3.3 Issues and Assumptions
This section summarizes the major issues and assumptions used to evaluate the cost of a full-scale
SWS® remediation of the Electro-Voice Superfund site in Buchanan, MI. In general, assumptions are based on
information provided by B&RE and observations made during the demonstration project.
3.3.1 Waste Volumes and Site Size
This economic analysis assumes that the site and wastes have already been thoroughly and properly
characterized and that these results were used to design the SWS* process; i.e. number, placement, and depth
of wells; amount of air injection and extraction; size of blower and vacuum pump; size of piping; valving
arrangements; etc. Therefore, it does not include the costs for treatability studies, waste characterization tests,
pilot studies or system design and layout. All of these activities would add to the costs and time required for
remediation.
For a full-scale cleanup, the treatment area was still assumed to be the vadose zone (depth = 46 ft), but
enlarged to an area of 100 ft x 125 ft, for a total volume of 575,000 ft3 (21,300 yd3). This is about ten times the
volume of soil that was treated under the SITE project.
38
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It is reasonable to assume that if the source of groundwater contamination lies within the vadose zone,
then any reduction in vadose zone contamination will translate to a reduction of groundwater contamination. This
was not evident from the SITE demonstration results, because significant concentrations of contamination were
not present in the groundwater beneath the treatment plot.
3.3.2 System Design and Performance Factors
The system design proposed by BAI to remediate contaminated soils associated within the dry well area
included 10 air injection wells, 15 vacuum extraction wells, and 10 sand chimneys. The number of wells and sand
chimneys proposed for the full-scale design is only slightly greater than that used for the SITE demonstration.
This means that the amount of overlap in the radius of influence between wells would be less. This would
translate into a level of removal less than what was achieved in the demonstration for a one year time frame.
However, if it is assumed that the full-scale system would give the same level of removal as that demonstrated
under the SITE project, then the cleanup would likely take longer. B&RE has suggested 3 years instead of 1 year.
The tacit assumption is that this level of removal is sufficient to meet regulatory standards.
It should be mentioned that sand chimneys have been incorporated into the design because of the highly
stratified nature of the soils at this site. For a site where the soils are more homogeneous, sand chimneys would
not normally be necessary. Their costs are minimal and have not been included here.
The Biological Emission Control (BEC)* units, which were designed to biologically degrade extracted
VOCs from the off-gas stream, were taken off-line a few months into the Demonstration when the exhaust off-
gasses met the site specific emission criteria. The off-gas was discharged without further treatment throughout
the remainder of the Demonstration. The same scenario was assumed for the full-scale remediation, i.e., no
effluent treatment of off-gasses. However, because this may not be the case at other sites, the cost of adding
carbon adsorption onto the back end of the system is discussed under "Effluent Treatment and Disposal Costs"
3.3.3 System Operating Requirements
The SITE project demonstrated that the equipment was quite reliable and required minimal operator
oversight Therefore, the system used for economic analysis was assumed to be operated 24 hours a day, 7 days
a week for 3 years continuously. Any maintenance, modifications or adjustments to the system were assumed to
be done during one of the 12 sampling events scheduled to take place every year.
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3.3.4 Financial Assumptions
\
For purposes of this analysis, capital equipment costs have been amortized over an assumed useful life
span of 10 years with no salvage value. Interest rates, inflation, or the time value of money have not been
accounted for. Insurance and taxes are assumed to be fked costs listed under "Startup" and are calculated as 10%
of annual capital equipment costs.
3.4 Basis for Economic Analysis
In order to compare the cost effectiveness of technologies in the SITE program, EPA breaks down costs
into the twelve categories shown in Table 3-1 using the general assumptions already discussed. The assumptions
used for each cost factor are discussed in more detail below.
3.4.1 Site Preparation
The amount of preliminary preparation would depend on the site, and was assumed to be performed by
the responsible party (or site owner) in conjunction with the developer. Site preparation responsibilities include
site design and layout, surveys and site logistics, legal searches, access rights and roads, and preparations for
support facilities, decontamination facilities, utility connections, and auxiliary buildings. None of these costs have
been included here.
The focus, instead, was on technology-specific site preparation costs. These are generally one-time
charges and are necessarily site-specific. They include the drilling and preparation of wells, SWS* installation
and construction oversight, utility connections, and a building enclosure to house the VCU and any associated
effluent treatment system(s).
40
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M :
ESTIMATE!* COST SWS* I
WEE A APPLICATION
COST CATEGORY
1. Site Preparation
Well Drilling & Preparation
Building Enclosure (10'xl5')
Utility Connections
System Installation
Total Costs
2. Permitting & Regulatory Requirements
3. Capital Equipment (amortized over lOyrs)
Vacuum Pump
Blower
Plumbing
Building Heater
TotaJ Costs
4. Startup
5. Consumables & Supplies
Health & Safety Gear
6. Labor
7. Utilities
Electricity(B lower & Pump)
El ectri c ity(Heater)
Total Costs
8. Effluent Treatment & Disposal Costs
9. Residuals & Waste Shipping & Handling
Contaminated Drill Cuttings
Contaminated PPE
Total Costs
10. Analytical
11. Maintenance & Modifications
12. Demobilization
TOTAL AHNUAL COSTS
TOTAL REMEDIATION COST
1st Year
$32,500
$10,000
$5,000
$15,000
$62,500)
$10,000
$450
$450
$3,333
$333
$4,566
$7,957
$1,000
$6,300
$3,900
$660
$4,560
N/A
$12,500
$6,000
$18,500
$20,000
N/A
Y^ar
$450
$450
$3,333
$333
$4,566
$1,000
$6,300
$3,900
$660
$4,560
N/A
$1,000
$1,000
$20,000
N/A
S37S426
3rd Yfear
$450
$450
$3,334
$334
$4,568
$1,000
$6,300
$3,900
$660
$4,560
N/A
$6,000
$3,000
$9,000
$20,000
N/A
$2,500
$475928i
$320,737
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Drilling and preparation (purging, casing, caps, etc.) of injection/extraction wells were assumed to be
performed by a subcontractor at an average cost of $1,300 per well. For a total of 25 wells --10 injection and
15 extraction, the total drilling cost is $32,500 ($ 1,300/well x 25 wells). B&RE has estimated that it would take
about 4 weeks @ 50 man-hr/wk to completely install the SWS® and provide construction oversight services.
Assuming a labor rate of $75/man-hr, the total cost of labor for system installation and construction oversight
would be $15,000 (4 wk x 50 man-hr/wk x $75/man-hr). Based on SITE demonstration experience, it was
estimated that utility connections would total about $5,000, and that a 10 ft x 15 ft building enclosure would cost
about $10,000 to construct.
Hence the total site preparation cost is estimated to be $62,500 and has been assigned only to the first-
year in Table 3-1.
3.4.2 Permitting and Regulatory Requirements
These costs may include actual permit costs, system health/safety monitoring, and analytical protocols.
Permitting and regulatory costs can vary greatly because they are very site- and waste-specific. Based on their
SITE demonstration experience, B&RE estimated permitting costs at about $10,000. Although some of these
costs may be spread out over the course of the project, the majority of these expenses will be incurred in the first
year.
i
3.4.3 Capital Equipment
Most of the capital equipment cost data were provided by B&RE. They include a 5 HP blower costing
$4,500, a 5 HP vacuum pump costing $4,500, and a 2,550 watt heater for the building enclosure costing $1,000.
This totalled $10,000, and the cost for plumbing (pipes, pipe fittings, valves, gauges, etc.) was assumed to cost
an equal amount, i.e. $10,000.
The cost of the blower and vacuum pump can be amortized over a 10-year useful life span because these
pieces of equipment can be removed at the end of the three year cleanup and used elsewhere. Hence, their
combined annualized costs would be $900 as shown in Table 3-1. The plumbing and heater, on the other hand,
would probably remain. Therefore, their combined costs ($11,000) will have to be amortized over 3 years, ®r
$3,667 annually as shown in Table 3-1 for every year of remediation.
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Since the BECs® were not used for a substantial part of the Demonstration, they are not included here.
However, the cost of including carbon adsorption to control emissions is discussed under "Effluent Treatment
and Disposal Costs".
3.4.4 Startup
Transportation costs are variable and dependent on site location, and size/weight load limits, which vary
from state to state. Transportation costs are only charged to the client for one direction of travel. Since they are
not expected to be a major factor, they are not included here.
Based on their SITE demonstration experience, B&RE has estimated that startup and shakedown testing
will require about 2 weeks @ 50 man-hr/wk. Assuming a labor rate of $75/man-hr, the total labor cost for startup
and shakedown would be about $7,500 (2 wk x 50 man-hr/wk x $75/man-hr). Fixed costs, such as insurance and
taxes, were included at a rate of 10% of the total annualized capital equipment costs, or $457 (0.1 x $4,566). The
total startup costs are $7,957 and have been assigned to the first year of remediation only.
3.4.5 Consumables and Supplies
The SVVS*, as applied to this site, did not employ any microbial inoculations or nutrient addition.
Therefore there are no costs attributable to that aspect of the process. The costs for maintenance supplies (spare
parts, oil, grease, lubricants, etc.) were considered negligible and so were not included either.
The only other item that may have to be included in this category is health and safety gear, and
miscellaneous supplies. This was estimated to be about $ 1,000/yr and is included as a yearly line item in Table
3-1.
3.4.6 Labor
Hourly labor rates include base salary, benefits, overhead, and general and administrative (G&A)
expenses. Travel, per diem, and rental car costs have not been included in these figures. If a site is located such
that extensive travel will be required, that could have a major impact on labor costs.
43
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Based on their experiences with the SITE demonstration, B&RE estimated that an average of 12
sampling events per year would be required to monitor and consequently modify and/or adjust the operation of
their system. Periodic routine maintenance tasks could also be done during these sampling events. They estimated
that each event would require 7 man-hr. Therefore, at $75/man-hr the total labor cost would be $6,300 (12
events/yr x 7 man-hr/event x $75/man-hr).
The labor associated with other tasks, such as site preparation, startup, and demobilization have been
assigned to those categories. The demobilization hourly rate is slightly lower ($50/man-hr) because B&RE feels
that less skilled labor would be required to accomplish this task.
3.4.7
The major utility demand for this project was electricity, primarily to run the blower, vacuum pump, and
heater. The blower and pump were both rated at 5 HP or 3.73 kW. Assuming electricity costs $0.06/kWh, the
annual utility costs associated with these two pieces of equipment are $3,900 (2 x 3.73 kW x 24 hr/day x 365
day/yr x $0.06/kWh). The heater would presumably be used only during cold weather. If it is assumed that this
would amount to no more than 180 days/yr, then the heater would cost $660/yr ( 2.55 kW x 24 hr/day x 180
day/yr x $0.06/kWh) to operate. The total of these would be $4,560 for each year of the cleanup.
3.4.8 Effluent Treatment and Disposal
Based on experience from this SITE demonstration, the off-gas was discharged without further treatment,
based on air dispersion modeling. That was also assumed to be the case for the full-scale remediation. Therefore,
no costs were assigned to effluent treatment and disposal. However, this may not be the case at other sites.
To get an idea as to how much impact this would have, a carbon adsorption unit was hypothetically
assumed to be required at the back end of the SWS*. The carbon unit was sized based on the SITE
demonstration result, that showed approximately 300 kg of VOCs were extracted over a one-year period. Since
the full-scale remediation assumes treatment of ten times the amount of soil treated during the SITE
demonstration, about 3,000 kg of VOCs were assumed to be extracted. If it is conservatively estimated that 10
kg of carbon are required for each kg of VOC extracted, then 30,000 kg of carbon would be necessary fgr
treatment over 1 year. It was also assumed that VOC concentrations in the extracted off-gas would be low enough
at the end of the first year that carbon adsorption would not be required for the remainder of the cleanup.
44
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Rental of a stainless steel vessel with 820 kg of vapor phase reactivated carbon (the largest size currently
available) would cost about $4,500/unit, including spent carbon handling and off-site reactivation. The unit would
have to be replaced 36 times over the course of a year (30,000 kg + 820 kg/unit). Additionally, there would be
a one-time RCRA carbon acceptance fee of $2,500 to sample the spent carbon to ensure safe reactivation.
Therefore, if treatment of the off-gas had been required, it would have cost an additional $164,500 ($4,500/unit
x 36 units/yr + $2,500).
3.4.9 Residuals & Waste Shipping. Handling, and Storage
During the SITE demonstration, approximately 1 drum of well cuttings was produced for each well. For
the full-scale remediation, this would translate to 25 drums of well cuttings. The cost to manifest, transport,
handle, and dispose of these was estimated at $500/drum. The cost to dispose of these is then calculated to be
$12,500 (25 drums x $500/drum). In the final year an additional 10 drums of well cuttings were assumed to be
generated due to regulatory site closure requirements. The only other residual that would require disposal is
personal protective equipment (PPE). It was assumed that 2 drums of PPE would be generated during the second
year and slightly more in the last year of cleanup. The total cost for this category is then $28,500.
3.4.10 Analytical Services
Based on their experience with the SITE demonstration, B&RE estimated that they would need to have
an average of 12 sampling events each year. The labor cost for this has been included under "Labor". However,
an additional expense associated with laboratory analyses needs to be included. The developer will use this
information to optimize the operation of his system by periodically adjusting or modifying its operation. This has
been estimated at $20,000 per year but may be as low as $ 10,000 per year and is included in Table 3-1.
3.4.11 Facility Modification. Repair, and Replacement
Based on experience from the SITE demonstration, no further modification, repair, and/or replacement,
other than routine system adjustment, was projected. As stated earlier, this is assumed to be done during the
sampling events, site preparation, or startup. No additional costs for this have been included.
45
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3.4.12 Demobilization
Based on their experience from the SITE demonstration, B&RE estimated that it would take 1 week @
50 man-hr/wk to demobilize the site. A labor rate of $50/man-hr was used because it was felt that a less skilled
level of effort was required to demobilize. The total cost for demobilization is then $2,500 (1 wk x 50 man-hr/wk
x $50/man-hr), which would be incurred in the last year of remediation.
3.5 Results
Table 3-1 shows the itemized costs for each of the 12 categories on a year-by-year basis for a
hypothetical 3 year mil-scale remediation of the Electro-Voice Superfund site located in Buchanan, MI. The total
cost to remediate 21,300 yd3 of soil was estimated to be $220,737 or $10.36/yd3. This figure does not include
any treatment of the off-gases. If effluent treatment costs are included, it would increase costs to $385,237 or
$18.09/yd3.
Figure 3-1 shows the relative importance of each category on overall costs. It shows the largest cost
component to be Site Preparation (28%), followed by Analytical Services (27%), and Residuals/Waste Shipping,
Handling & Storage (13%). Labor accounted for a relatively small percentage (9%). This is indicative of the fact
that the SWS® is a relatively reliable, non-labor intensive process. (However, travel, per diem, and car rental
expenses were not included.) These four categories alone accounted for 68% of the costs. Utilities and Capital
Equipment each accounted for about 6%, and the remaining categories each accounted for 5% or less. If effluent
treatment costs had been included, it would have accounted for over 43% of the total cleanup cost.
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FIGURE 3-1
Remediation Cost Breakdown (3 yrs.)
(Without Effluent Treatment)
Site Preparation 28.3%
Analytical 27.2%
Residuals 12.9%
mobilization 1.1%
& Supplies 1.4%
Labor 8.6%
Utilities 6.2%
'Capital Equipment 6.2%
(With Effluent Treatment)
Site Preparation 16.2%-
Analytical 15.6%
Effluent Treatment 42.7%
jilization 0.6%
msumables & Supplies 0.8%
2.1%
Permitting 2.6%
'Utilities 3.6%
Capital Equipment 3.6%
Labor 4.9%
Residuals 7.4%
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SECTION 4
TREATMENT EFFECTIVENESS
This section presents the results of the SITE demonstration conducted at the Electro-Voice Facility
located in Buchanan, Michigan. The section discusses the effectiveness of the SWS® in remediating subsurface
VOC contamination near the facility's former dry well.
4.1 Background
The SWS® SITE Demonstration was conducted at the Electro-Voice Facility in Buchanan, Michigan.
Electro-Voice, Inc. contracted Brown & Root Environmental (formerly Halliburton NUS Environmental
Corporation) to install and operate an SWS® over a one-year period. Baseline and system operations data were
gathered to evaluate the effectiveness of the system for remediating volatile organic compound (VOC)-
contaminated soils related to former paint waste disposal practices at the facility. The results would be used to
provide a justification for the execution of an Explanation of Significant Difference (BSD) to the Record of
Decision (ROD) for Operable Unit Number One.
Electro-Voice, Inc. is an active facility in the business of manufacturing audio equipment. The
technology was installed and tested in an open field behind the facility where paint shop wastes had previously
been discharged to the subsurface via a dry well. The dry well was installed in 1964 as part of the facility's
automated painting system and was used to dispose of liquid waste via a gravity drain connected to a sink in the
paint shop. Use of the dry well had been discontinued by 1973. Soil sampling conducted during a Remedial
Investigation, and subsequently by the USEPA SITE Program, indicated that petroleum and chlorinated aliphatic
hydrocarbons were detectable in soil samples throughout much of the vadose zone of the "dry well area". The
magnitudes of these contaminants are most significant in soil samples acquired in the immediate vicinity of the
former dry well. The greatest concentrations of VOCs were encountered in a subsurface horizon referred to as
the "sludge-layer". This sludge layer, occurring 12 to 18 feet below the surface, is a discolored clay-rich horizon
containing filtrate from wastes that have leached from the dry well.
A VOC analysis of the sludge layer from the SITE Demonstration Pretreatment Borehole SB-16, drilled
at the location of the former dry well, yielded toluene, ethylbenzene, and total xylenes at concentrations of 4,300
mg/kg, 1,400 mg/kg and 6,600 mg/kg respectively. Tetrachloroethene, trichloroethene and 1,1,1-trichloroethane
48
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were also detected at 240 rag/kg, 23 mg/kg and 18 mg/kg respectively. The remedial investigation (RI) report
for the Electro-Voice site states that the total mass of contamination associated with the dry well soils may be
as much as 1,000kg.
Under the SITE Program, the SWS* was evaluated for its ability to reduce volatile organic contaminants
in the vadose zone soils of the "dry well" area. The critical objective of the demonstration was to evaluate the
developer's claim of a 30% reduction in the sum of the concentrations of seven specific volatile organic
compounds (i.e., benzene, toluene, ethylbenzene, xylenes, tetrachloroethene, trichloroethene and 1,1-
dichloroethene) in vadose zone soils of the treatment plot over a 12 month period of operation. It is important
to note that the one year time frame was chosen for testing purposes only, and the reduction claim does not reflect
the limits of the technology. During an actual clean-up, the system may require longer time than was possible
under the present study.
Secondary objectives for the Demonstration Test are as follows:
• Monitor the reduction of volatile organic compounds in the saturated soil and groundwater
within the SWS* Treatment Plot.
• Monitor the impact of the technology on the groundwater outside the immediate treatment area.
• Qualitatively determine the magnitude of contaminant reduction due to vapor extraction versus
in-situ biodegradation by performing a baseline soil gas test and three shut-down soil gas
monitoring tests.
• Determine the magnitude of reduction of individual contaminants (benzene, toluene,
ethylbenzene, xylenes, tetrachloroethene, trichloroethene and 1,1-dichloroethene) within vadose
zone soils of the dry well area.
• Monitor general soil conditions (i.e., nutrients, toxics) that might inhibit or promote the system's
effectiveness, such as: Total Carbon (TC), Total Inorganic Carbon (TIC), Nitrate, Phosphate,
Ammonia, Total Kjeldahl Nitrogen, Sulfate, Alkalinity, Total Metals plus Mercury, Cyanide,
pH, and Particle Size Distribution (PSD).
• Monitor the effectiveness of the biofilter in the reduction of VOC contamination in the extracted
air stream.
• Monitor the extracted air stream to qualitatively assess biodegradation in the treatment plot over
the course of the demonstration.
• Develop an estimation of operating costs for the SWS* technology in remediating VOC
contamination.
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4.2 Detailed Process Description
The SWS®, developed and designed by BAI, and operated by B&RE under a licensing agreement,
integrates the benefits of both vapor extraction and bioremediation in the removal and destruction of all phases
of organic contamination from the subsurface. Vapor extraction removes the easily-strippable volatile
compounds from the soil and/or groundwater and appears to be the dominant mechanism during the early phases
of remediation. Bioremediation, more specifically biostimulation, processes are more dominant in the later phases
of a remediation and are used to accelerate the in-situ destruction of organic compounds in the soil and
groundwater. The combined application of the technologies results in remediation that is more rapid than the
use of biostimulation alone, while generating lower quantities of volatile organics than conventional vapor
extraction technologies. An additional benefit is the remediation of contaminants that would not normally be
remediated by vapor extraction alone (chemicals with lower volatilities and/or chemicals that are more tightly
sorbed). The result is an integrated technology that translates into lower costs and faster remediations.
A typical SWS* is comprised of a network of air injection and vacuum extraction wells designed to
circulate air below the ground to:
• Volatilize and remove volatile organic contaminants from the groundwater and soil
• Increase the flow of oxygen in the soil to enhance the rate of in-situ transformations and
destruction of organic contaminants by indigenous soil microbes.
An SWS* is custom-tailored to address specific site conditions. A typical SWS consists of
alternating air injection and vacuum extraction wells aligned together in rows referred to as reactor lines. The
number and spacing of the wells depends upon modeling results of applying a design parameter matrix, as well
as the physical, chemical and biological characteristics of the site. The reactor lines are linked together and
plumbed to a central vapor control unit (VCU) used to house air injection and vacuum pumps, gauges, control
valves and other process control hardware. The VCU may also house an emission treatment system. One or more
vacuum pumps are used to create negative pressure to extract contaminant vapors and control vapor migration,
while an air compressor simultaneously creates positive pressure across the treatment area. Vacuum extraction
wells are generally placed above the water table and are typically screened in the zone of maximum contamination
to better focus remedial stresses. Air injection wells are screened below the groundwater table. The exact depth
of the injection wells and screened intervals are site-specific design considerations. Depending on groundwater
depths and fluctuation, horizontal vacuum screens, "stubbed" screens, or multiple-depth completions may be an
50
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option. Solar panels or passive heated air injection may also enhance subsurface volatilization, particularly in
the winter months. Additional valves may be placed on individual reactor lines or on the individual wells for
better control of air flow and pressure. The SWS* design allows positive and negative air flow to be shifted to
different locations of the treatment plot so as to concentrate remedial stress on those areas requiring it.
The SWS® at the Electro-Voice site is comprised of three separately-valved reactor lines. Figure 4-1
presents a schematic diagram of the SWS* configuration at the Electro-Voice facility. The Electro-Voice design
consists of 11 vacuum extraction wells and 9 air injection wells, each separately valved for optimum system
flexibility and air flow control. The air injection wells are installed into the water table with a one foot screened
interval positioned approximately 10 feet beneath the water table in the dry well area (water table in the dry well
area is approximately 50 feet below grade). The vacuum extraction wells were installed such that a five-foot
section of screen is set to intersect the "sludge layer". The extraction wells were installed with a five-foot blank
with a drain port attached to the bottom of the screen to control condensation. A number of sand chimneys were
installed to better facilitate vertical air circulation throughout the plot. The injection and vacuum air supply lines
of each reactor line are manifolded to a single injection and vacuum line inside the VCU Building. The pumps
used during the SITE Demonstration are BAIV5, capable of 85 cubic feet per minute (cfm) reverse pressure air
flow, and BAI A5, capable of delivering 120 cfin air flow. Typically, the positive (injection) pressure pump flow
rate is maintained at approximately 80% of the vacuum pump flow rate. In addition to the various technology
control systems, the VCU contained the Biological Emission Control (BEC)* units to further reduce levels of
VOC in the extracted air stream prior to release to the atmosphere.
The soil vapor extraction element of the process operates by pumping clean air into the injection wells
to percolate upward through the saturated and unsaturated zone, making contact with volatile organic
contaminants. The continuous circulation of clean air encourages the mass transfer of bulk liquid, dissolved and
sorbed phase contamination to the vapor phase. Vacuum extraction wells installed in the vadose zone pull the
percolated air through the soil under vacuum, further enhancing the mass transfer or stripping of contaminants
and control the migration of contaminated vapors.
51
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The increased circulation of air in the groundwater and soil, specifically oxygen, also stimulates and
accelerates natural biodegradation. A steady supply of oxygen allows those microbes that respire aerobically to
utilize the organic contaminants as a food source, thus converting these organic substrates to cell material and
energy for metabolic processes. By-products of these metabolic reactions are carbon dioxide and water. As long
as oxygen is supplied, and a food source remains, the microbial populations proliferate and biodegradation rates
increase.
During the early stages of an SWS® operation, the overall rate of mass transfer of contaminants to the
vapor phase may exceed the biodegradation rates. This phase, according to the developer, may last anywhere
from two weeks to a few months. The extracted vapors may need to be treated above ground before release to
the atmosphere. The amount of treatment will decrease steadily over this period until biodegradation rates
surpass the net rate of transfer of contaminant mass into the circulating air. When this point is reached, the vapor
extraction off-gas will consist predominantly of carbon dioxide and water, and treatment of the exhausted air
stream should no longer be necessary.
4.3 Methodology
The primary goal of the project was to determine the effectiveness of the SWS* in reducing VOC
contamination in the vadose zone. In order to determine the effectiveness of the technology, contaminant levels
in the vadose zone prior to installation were compared to contaminant levels after one year of operation. Soil
samples were collected from randomly-located borings within the physical boundaries of the SWS* system and
composited in such a manner that the entire vertical section of the vadose zone was represented. Because the
developer's claim was to reduce seven volatile organic contaminants by 30%, benzene, toluene, ethylbenzene, and
xylenes (BTEX), as well as tetrachloroethene (PCE), rrichloroethene (TCE), and 1,1-dichloroethene (1,1-DCE)
were considered the critical parameters for this demonstration. Analyses were also performed on select samples
for the following non-critical parameters: total carbon (TC), total inorganic carbon (TIC), nutrients (nitrate,
phosphate), total metals plus mercury, cyanide, pH, and particle size distribution (PSD). An additional objective
of this demonstration was to develop data on operating costs for the SWS* technology.
Pre-treatment sampling activities were conducted to establish a baseline. It was estimated that 77
samples were statistically required to evaluate the developer's claim of 30% reduction, based on subsurface
contaminant variability, derived from the analysis of paired Predemonstration borehole characterizations. Soil
53
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samples were obtained from 20 boreholes randomly positioned within the treatment plot (Figure 4-2). Distinct
sub-surface horizons were classified according to lithology and contaminant levels. The horizons were designated
the Upper Horizon, Sludge Layer, Lower Horizon Al, Lower Horizon A2, Lower Horizon B, and the Saturated
Zone. Samples were collected from each of these horizons. These borehole samples were extracted/composited
into methanol in the field and shipped to the contract laboratory to be analyzed for VOCs to establish the initial
vadose zone concentrations in the contaminated area within the treatment system. After sampling, all boreholes
were backfilled with clean fill possessing textural properties similar to the soil removed from the borehole, so as
not to influence the operation of the treatment technology.
Saturated zone samples were considered non-critical and were not part of the sample set for claim
evaluation. The impact of the technology outside the immediate treatment area was inferred based upon
subsurface pressures measured at pressure probe stations installed around the perimeter of the treatment plot.
Groundwater quality was monitored by collecting samples from existing groundwater monitoring wells
MW-1, MW-2, MW-3, MW-4, and predemonstration well SAIC MW-1 at times 0,3,6,9 and 12 months. These
samples were also analyzed for VOCs for determination of a secondary objective. The monitoring wells are
located approximately 100 to 200 feet down and across gradient from the treatment plot.
The magnitude of contaminant reduction due to vapor extraction versus in-situ biodegradation was
qualitatively determined by conducting system "shut-down" tests and monitoring carbon dioxide (CO2), oxygen
(02) and total hydrocarbons (THC) in the gas. These tests occurred in the first month (to establish baseline
conditions), at 6 months, and upon completion of the demonstration after 12 months.
Analyses on the extracted air stream were utilized to evaluate the soil vapor extraction (S VE) component
of the technology. Air samples were periodically collected before and after the BEC* devices, and were analyzed
for critical volatile components. Volumetric flow rates were also measured to determine mass removal rates of
extracted vapors.
54
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Figure 4-2
Pre-Treatment Sampling Locations
at the Electro-Voice Site
Legend
Inj- Injection
Vac- Vacuum
I - Study Area
• - Soil Borings
NOT TO SCALE
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4.4 Performance Data
This section presents the performance data gathered by the testing methodology described above. Results
are presented and interpreted in the subsequent sections. Data is presented in tabular and/or graphic form.
4.4.1 Results from Pre-Treatment Study
A review and analysis of the pre-treatment VOC data from the 120 vadose zone samples indicate that
a significant portion of the designated treatment area (thirteen boreholes; SB-1,3,4,5,6,9,10,11,12,13,14,
15, and 17) had target VOC concentrations near or below their respective detection limits and thus did not serve
as an appropriate test matrix to determine the capability and effectiveness of the SWS* treatment technology.
The sparsely-contaminated portion of the treatment area containing these thirteen boreholes is designated Zone
Hand is shown in Figure 4-3. Data from the remaining seven boreholes (SB-2, 7, 8,16,18, 19, and 20) defines
an appropriately contaminated area to evaluate the SWS*. This area is designated Zone I as depicted in Figure
4-3.
Post-treatment sampling utilized 14 boreholes drilled in the redefined hot-zone (Zone 1) with paired
boreholes at each of the seven pre-treatment boring locations. Paired boreholes were selected in order to reduce
statistical variability. In addition to the fourteen boreholes in Zone 1, post-treatment samples were recovered from
Zone II boreholes SB-1, 3, 6, 9, and 10. These were recovered to insure that contamination was not migrating
to these portions of the site.
4.4.2 Summary of Results - Primary Objectives
The developer's claim for a 30% reduction in vadose zone contamination was greatly exceeded. The
average reduction in the sum of the critical volatile components averaged 80.6% over a one year period. This
value was calculated from the boreholes in the hot-zone (Zone I). The average concentration before
implementation of the SWS* was 341.5 mg/kg; this average was reduced to 66.2 mg/kg after one year of
operation. A t-test was performed on log normal transformed total VOC data to determine if the reductions
observed were significant. The results of the t-test indicate that the reductions observed were significant with
a 90% confidence level.
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Area Excluded From System Evaluation
Post Treatment Sampling Area
Figure 4-3
Revised Post-Treatment Sampling Locations
at the Electro-Voice Site
LEGEND
Inj - SVVS ® Injection Well
Vac - SVVS ® Vacuum Well
% - Pre-Treatment Soil Borings
O ' Post-Treatment Soil Borings
NOT TO SCALE
-------
Table 4-1 summarizes the performance of the SWS® by sub-surface horizon, and Figure 4-4
graphically depicts the data. The highest concentration of the critical VOCs occurred in the sludge layer, which
had an average concentration of 1,661 mg/kg before implementation of the system. After one year of operation,
the concentration in the sludge layer was 308 mg/kg, an 81% reduction in contamination. Pre-treatment
concentrations in the other zones ranged from 14 mg/kg to 322 mg/kg, with post-treatment concentrations
averaging less than 1 mg/kg for all horizons (98 to >99% reductions). Figure 4-5 is a plot of the percent
reduction versus initial concentration for all sub-surface horizons in each borehole. The plot shows no strong
correlation between initial concentration and reduction effectiveness; therefore, the technology is not limited by
concentration, and is operative over a wide contaminant concentration range.
Performance of the SWS* over the areal extent of the entire treatment plot (Zones I and II) is illustrated
by comparing pre-treatment and post-treatment contaminant maps for the entire vadose zone (Figure 4-6), as well
as for each sub-surface horizon (Figures 4-7 to 4-10). As previously discussed, a large portion of the treatment
plot contained very low concentrations of contaminants as illustrated in Figure 4-6a. The installation and
operation of the system in an uncontaminated portion of the site did not affect the performance of the system in
the highly contaminated portion, as illustrated in the post-treatment contaminant map (Figure 4-6b). However,
installation of the system in non-contaminated sub-surface soils is an inefficient use of resources that may impact
remedial cost. This situation emphasizes the need to accurately define the location and extent of sub-surface
contamination prior to implementation. Cost-effective in-situ remediation technologies require a high level of
site characterization to insure that the treatment agents are reaching the impacted media.
An analysis of the contaminant maps before and after treatment for individual layers (Figures 4-7 to 4-
10) reveal that the sludge layer is the only layer that did not undergo almost complete remediation. The sludge
layer did exhibit significant reductions in contaminant concentration and areal extent as a result of the SWS®.
4.4.3 Changes in Individual Critical VOCs
The effectiveness of the SWS* treatment on individual critical VOCs is summarized in Table 4-2 and
graphically depicted in Figures 4-11 and 4-12. Pre-treatment soil analyses indicate that the non-
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PRETREATMENT
SAMPLING
POST-TREATMENT
SAMPLING
Upper Horizon
321.77
0.74
99.77%
Sludge Layer
1661.03
307.69
81.48%
Lower Horizon Al
96.42
0.98
98.99%
Lower Horizon A2
37.68
0.42
98.88%
Lower Horizon B
13.57
0.30
97.79%
* Sum of Benzene, Toluene, Ethylbenzene, Xylene, 1,1-Dichloroethene, Trichloroethene and
Tetrachloroethene
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Figure 4-4 SWS™ Performance by Horizon
Non-Sludge Layers
Sludge Layer
CTS
O
Legend
Before Treatment
After Treatment
2000-i
•5-1500-
51000-
500-
T 1 r
I Lower Horizon A1 I Lower Horizon B
Upper Horizon Lower Horizon A2
Before Treatment
After Treatment
Sludge Layer
-------
Figure 4-5 Percent Reduction as a Function of
Initial VOC Concentration
100
95
90
c
t>
!
oc
85
80
75
70
65
60
A
+
Legend
Upper Horizon
Sludge Layer
Lower Horizon A1
Lower Horizon A2
Lower Horizon B
0.1
—r~
10
100
1000
1
10000
Initial Concentrations (mg/kg)
-------
ON
to
Figure 4-6(a)
Pre-Treatment Contaminant Map:
Entire Vadose Zone
Figure 4~6(b)
Post-Treatment Contaminant Map-
Entire Vadose Zone
-------
Figure 4-7(a)
Pre-Treatment Contaminant Map-
Upper Horizon
•*-<••
Figure 4-7(b)
Post-Treatment Contaminant Map-
Upper Horizon
-------
Figure 4-8(a)
Pre-Treatment Contaminant Map-
Sludge Layer
Figure 4-8(b)
Post-Treatment Contaminant Map:
Sludge Layer
-------
Figure 4-9(a)
Pre-Treatment Contaminant Map:
Lower Horizon A
Figure 4-9(b)
Post-Treatment Contaminant Map-
Lower Horizon A
-------
0\
Figure 4-10(a)
Pre-Treatment Contaminant Map-
Lower Horizon B
Figure 4-10(b)
Post-Treatment Contaminant Map:
Lower Horizon B
-------
^MNwrotfM,.
PRETREATMENT
SAMPLING
POST-TREATMENT
SAMPLING
Benzene
0.01
0.00
Toluene
92.84
14.42
84.47%
Ethylbenzene
37.41
6.06
83.81%
Xylenes
205.50
45.28
77.97%
1,1 -Dichloroethene
0.01
0.00
Trichloroethene
0.36
0.00
Tetrachloroethene
5.37
0.44
91.81%
* A meaningful % reduction can not be provided due to low Pretreatment concentrations.
67
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Figure 4-11 Magnitude of Reduction of Individual
Critical VOCs
oo
250-1
>200-
•150-
£
o
§
O
Before Treatment
After Treatment
100-
50-
Benzene
Toluene I Xylenes I Trichloroethene I
Ethylbenzene 1,1-Dichloroethene Tetrachloroethene
Critical VOCs
-------
OS
Figure 4-12
100
80
o
1
0)
o
o
O
O
3
.2
§
i.
60
40
20
Relative Distribution of Individual Soil VOCs
Before and After Treatment
Legend
Before Treatment
After Treatment
In
I
m
Ethyl benzene
Toluene
ml
Xylene
1
Trichloroethene
Tetrachloroethene
1,1-Dichloroethene
Benzene Represented 0% of Total
Critical Concentration in the Soils
-------
halogenated VOCs are present in higher concentrations than the halogenated VOCs. Xylene is the most prevalent
compound, comprising approximately 60% of the VOCs both before and after treatment, followed by toluene,
ethylbenzene, and tetrachloroethene (Figure 4-11). Figure 4-12 also illustrates that the relative distribution of
volatile components in the soil is similar before and after the treatment, indicating that the technology does not
selectively remove or destroy one component over another.
4.4.4 Effect of the SWS® on VOCs in the Saturated Soil and Groundwater Within the Treatment Plot
In addition to evaluating the SWS®'s performance in reducing contamination in vadose zone soils of
the treatment plot, the technology was evaluated for its ability to effect remediation of groundwater and saturated
soil within the physical boundaries of the treatment plot., Except for 1,1-dichloroethene, detected at 12 ng/kg
during the first round of groundwater sampling in December of 1992, all remaining sampling events conducted
as part of the Demonstration did not yield any detectable levels of contamination from this well. These results
stand in contrast to the results obtained during Predemonstration sampling in July 1992 at the time the well was
installed, when PCE (0.63 ug/1), toluene (10 ug/1), ethylbenzene (5.8 ug/1), and total xylenes (23.6 ug/1) were
detected. With the possible exception of 1,1-dichloroethene, the absence of these contaminants in later
groundwater samples can not be directly attributed to removal by the technology, since the technology was not
turned on until March 1993, and the contaminants yielded during the Predemonstration round were absent in the
"Baseline" round conducted in December 1992. The data also show that the SWS* did not merely transfer
contaminants from the vadose zone to the groundwater, but removed them from the affected matrix entirely.
Contaminant reduction in saturated zone soils was comparable to trends observed in the vadose zone
horizons. Levels of contamination measured during Pretreatment sampling are of similar magnitude to those
measured in the less contaminated vadose horizons, with xylenes, toluene and ethylbenzene being the major
components. A comparison of the weighted sums of saturated zone VOC contamination before and after
treatment reveals that a 99.35% reduction was achieved after one year of treatment. These weighted
concentrations of the sum of the seven critical VOCs prior to treatment and after treatment were 37.88 mg/kg
and 0.24 mg/kg, respectively. Although the developer did not make any specific claims pertaining to expected
removals in the saturated zone, the reductions that were achieved were comparable to those observed in vadose
zone horizons, which greatly exceeded the developer's claim of a 30% reduction.
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4.4.5 Effect of the SWS® on VOCs in the Groundwater Outside of the Treatment Plot
The impact of the technology on groundwater outside the treatment plot was also evaluated. Four
monitoring wells from the existing Electro-Voice monitoring well network were selected for this purpose.
Based upon the position and distance of these wells relative to the treatment plot, coupled with the fact
that only one well consistently showed appreciable levels of aromatic hydrocarbon contamination, few
conclusions can be drawn on the effectiveness of the SWS® technology on groundwater outside the treatment
plot. Although there is little doubt that the dry well is the source of the contaminants found in this well,
contamination, based upon field observation during the demonstration, is most likely due to localized infiltration
of surface water runoff from the dry well area, rather than groundwater migration. It is interesting to note,
however, that contaminant levels showed a decreasing trend over the last six months of SWS* operation.
Whether this is due to seasonal factors controlling run-off, or is a reflection of the reduction observed in the upper
horizon and sludge layer (both likely sources for contaminants migrating via the surface water pathway), is
uncertain.
4.4.6 Impact of Soil Conditions on the SWS®
During Pretreatment and Post-Treatment soil sampling, samples were collected for various other
parameters that might inhibit or promote the system's effectiveness. Many of these parameters were collected
at the request of the operator to assess the availability of nutrients for in-situ bioremediation. The operator's
analysis of pretreatment nutrient availability, which was based on a comparison of the mean concentrations of
ammonia, nitrate and total kjeldahl nitrogen suggests that nitrogen is associated predominantly with organic
material in the form of biomass. The operator concluded that even before the SWS* was turned on, viable
microbial populations existed in the dry well area soils. Other nutrients, such as phosphorus and sulfur, were also
measured in vadose zone soils of the treatment plot. The operator conducted an evaluation of the subsurface
nutrient requirements necessary to sustain bacterial viability and growth. These were based on the assumption
that the total mass of organic contamination in the dry well was biodegradable. Based on the estimated mass of
TKN, ammonia and nitrate in treatment plot soils, the operator concluded that there were sufficient quantities of
nitrogen available to metabolize the total mass of contamination. The same conclusions were drawn for
phosphorus.
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According to the operator, macronutrients including calcium, potassium and sodium occur in vadose zone
soils at concentrations that favor microbial growth and viability. Iron and magnesium levels are elevated above
background values as a result of leaching from buried metal and other debris within the fill that comprises the
upper 20 feet of the site.
4.4.7 Extracted Vapor Assessment
The extracted off-gas vapor stream was periodically monitored and characterized to assess the
contribution of Soil Vapor Extraction (SVE) processes in the SWS®. Figure 4-13 shows the flow rate of the
vapor stream and the mass removal rate of total VOCs over the course of the treatment. These measurements
were taken at the inlet to the BEC* units. The flow rate of air fluctuated between approximately 60 dscfrn and
120 dscfin. The results of this study show typical SVE behavior, suggesting that pore volume exchange rates were
higher than what is typically considered optimal for biostimulation.
The mass removal rate of VOCs was high at the beginning of the treatment when soil VOC
concentrations were elevated and transfer to the vapor phase occurred easily. As VOC concentrations in the soil
decreased over the course of the remediation, the mass removal rate also decreased and stabilized, despite elevated
flow rates. This phase of the remediation is characterized by removal rates limited by diffusion of the volatile
organics from the solid phase to the air stream. The resulting pattern of soil vapor extraction is characterized as
high removal rates during the initial operation of the unit, followed by steadily decreasing removal rates during
the middle part of the remediation, ending with low and constant removal rates.
Figure 4-14 compares the relative distribution of VOCs in the extracted air stream at the start of the
remediation to the distribution at the end of the remediation. The distributions are similar except for higher
contributions of tetrachloroethene, and the absence of ethylbenzene, at the end of the treatment period.
The relative distribution of individual VOCs in the soil is compared to the relative distribution in the
extracted air stream, both at the beginning and at the end of the treatment period (Figures 4-12 and
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Figure 4-13 Extracted Vapor Stream Over Time
200
250
300
350
400
ELAPSED TIME (DAYS)
D Air(dscfm) o Total VOCs (gm/hr)
73
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Figure 4-14
Relative Distribution of Individual
Air Stream VOCs Before
and After Treatment
100
I
S.
80
o
I
§
§ 60
O
O
§
40
20
Legend
Before Treatment
After Treatment
Ethyl benzene
Toluene
Trichloroethene I Tetrachloroethene
Xylene 1,1 -Dichloroethene
Benzene Represented 0% of Total
Critical Concentration in the Extracted
Air Stream
74
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4-14). Relative to the soil, the extracted air stream is enriched in toluene and the halogenated VOCs
(trichloroethene, 1,1-dichloroethene, and tetrachloroethene).
4.4.8 Impact of Biodegradation on Contaminant Removal
Developers of the SWS* technology claim that biodegradation is an important remediation mechanism
for the destruction of organic contaminants in the sub-surface. Biodegradation dominates during the middle and
latter phases of the remediation after the easily stripped-volatiles are removed by SVE. This SITE Demonstration
attempted to assess the contribution of biodegradation to the overall reduction of contaminants observed in the
subsurface.
The primary measurement tool was the execution of shut-down tests. These shut-down tests monitor
changes in sub-surface oxygen and C02 following cessation of in-situ ventilation. The magnitude of bacterial
processes is directly proportional to the rate of oxygen depletion. Therefore, these shut-down tests measure the
presence and magnitude of bacterial processes operative on all organic matter (natural and anthropogenic), and
do not directly measure the degradation of specific contaminants. It is generally assumed that stimulation of
bacterial processes will result in the accelerated breakdown of biodegradable organic contaminants.
The three shut-down tests were performed at the beginning, middle, and end of the one-year remediation.
Oxygen and CO2 were measured at extraction wells throughout the site, allowing for the determination of
biodegradation around the entire site. The results of the shut-down tests provide the following qualitative
assessment of the role of biodegradation in the SWS* process.
The magnitude of biodegradation was greatest in the southern portion of the site where contamination
was found to be the highest. Within the southern portion of the site, the highest biodegradation rate was
encountered from an extraction well located adjacent to a soil boring containing high levels of contaminants. The
correlation between high biological activity and contaminant occurrence suggests that the technology was able
to stimulate biodegradation of contaminants.
A comparison of the three-shut down tests indicates that biological activity was greatest during the early
part of the remediation, moderate in the middle, and lowest at the end. (For a more in-depth analysis, the reader
is referred to the TER.) This is consistent with the hypothesis that biological activity would decrease as the
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remediation proceeds due to the reduction of electron acceptors (organics) in the sub-surface. However, the
middle shut-down test revealed that the level of bio-activity did not decrease as rapidly as the decrease in
hydrocarbons from vapor extraction. This would support the developer's claim that biological processes play an
increasingly important role, relative to vapor extraction, as the remediation proceeds.
4.4.9 Performance of EEC* Units
The Biological Emission Control (BEC)* system could not be evaluated since it was taken out of
operation a few months into the Demonstration when the exhaust off-gasses met the State imposed discharge
criteria set for operations at the Electro-Voice site. During the brief time the BEC® units were in operation, the
operator was only observing 30 to 40 percent reductions in system off-gasses. According to the operator greater
reductions may have been achieved given sufficient time for the microbes in the BEC* units to acclimate to the
concentrations in the system's off-gasses. Throughout the remainder of the year long demonstration, only a small
percentage of the combined volumetric flow of the air from the extraction wells was routed through the BEC*
units. This was done to maintain a population of viable microorganisms should off-gas scrubbing become
necessary again.
4.4.10 Process Operability and Performance at the Electro-Voice site.
This section summarizes the operability of the process and the overall performance of the SWS* at the
Electro-Voice site. It includes discussions about developments and problems encountered, along with the manner
in which these items were resolved.
When the SWS* was constructed during July and August of 1992, the intent was to completely
encapsulate the location of the former dry well, and the adjoining areas most significantly affected by dry well
contamination. Existing data compiled in the Remedial Investigation Report and interviews with facility
personnel were used in the conceptual design and the location of the SWS* reactor lines at the Electro-Voice
site. The location of SAIC's Predemonstration monitoring well (SAIC MW-1) marks the spot believed to have
been occupied by the former dry well. During the installation of the SWS®, a concentration of cobbles and sheets
of corrugated metal were encountered while laving down the trench between the middle and western reactor line.
This area of buried cobbles and sheet metal, located near SWS® injection well AI-13 and vapor extraction well
VE-20, has been inferred to be the former dry well. Contamination trends yielded during Pretreatment sampling
would support this, as the bulk of viable vadose zone contamination appeared to be limited to the southern third
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of the treatment plot, whereas the remainder of the treatment plot was characterized by VOC concentrations at
or near their respective detection limits. Based on this information, a significant portion of the treatment system
was installed over areas unaffected by the dry well. As a result, the SITE Demonstration Pretreatment data
suggest that a substantial area of dry well contamination might lie outside the physical boundaries of the SWS®
plot. These revelations did not seem to affect the performance of the SWS® but certainly influenced the
operation of the system; northern vapor extraction wells and injection wells were taken out of service after a few
months of system operation. Eventually only a small percentage of the wells were operating as a consequence
of remedial stresses being shifted to the southern edge of the treatment plot. The inaccurate location of the
SWS® process resulted in a somewhat inefficient operation.
Due to special circumstances at the Electro-Voice site, the operator was able to exhaust vacuum
extraction off-gas to the atmosphere with little or no treatment. The Electro-Voice site may not be a typical
example of SWS® operation, particularly with regard to the handling of extracted vapors. Tighter air emission
controls at other sites might necessitate the employment of the EEC* units, followed by vapor phase activated
carbon, which could increase operational costs by a factor of 1.5 to 2.0. It is likely that additional costs
associated with the treatment of system off-gasses would be minimized by controlling vacuum extraction
emissions within the regulatory standards, through the adjustment of air injection and vacuum extraction rates.
The downside of stepping back injection and extraction rates would be an extension of remediation time;
however, the costs associated with extending system operation should be minor in comparison with costs related
to activated carbon treatment. The high reduction rates achieved at the Electro-Voice site after one year of
treatment might be exceptional, since the air emission standards at the site allowed the SWS* to be operated
more in a vapor extraction mode, which favored mass transfer of contaminants to the vapor phase over in-situ
biostimulation. This is not to say that in-situ biodegradation did not occur; in fact there is compelling evidence
suggesting that it was operative throughout the demonstration, but it was not optimized based on observed
vacuum extraction air flows.
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4.5 Process Residuals
The actual S WS® process generates few if any residuals. During the winter months as injected and
extracted air is cooled, it is possible for several gallons of condensate to accumulate in the lines. Occasionally,
enough condensate will accumulate that it will interfere with the operation of the system. When this occurs, the
condensate must be siphoned out of the lines. Since the air streams that formed this condensate contained vapor
phase contaminants, it is possible that the contaminants partitioned into the condensate. This condensate might
therefore be contaminated and require special handling with regard to storage and disposal. Its more likely that
the small amounts of condensate that are generated from time to time would simply be used to make up
evaporative losses of water in the EEC® units, whereby the condensate would be effectively treated in the
biofilters.
During system installation a number of process residuals are generated. During the installation of wells
and the horizontal emplacement of vacuum extraction and injection lines, potentially contaminated soil cuttings
are produced. As a consequence, used PPE and contaminated water from decontamination activities are also
generated. All of these items, if found to be hazardous, must be containerized and disposed of as hazardous
waste.
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SECTION 5
OTHER TECHNOLOGY REQUIREMENTS
5.1 Environmental Regulation Requirements
Federal, state and local regulatory agencies may require permits to be obtained prior to implementing
the SVVS® process. Most Federal permits will be issued by the authorized state agency. Federal and state
requirements may include obtaining a hazardous waste treatment permit or modifying an existing permit
regulating these activities on a given site. A permit would be required for storage of contaminated soil in a waste
pile for any length of time and for storage in drums on-site for more than 90 days. Air emission permits will
probably be required, although such items as site location, off-gas volumetric flow rates and expected VOC
concentrations will dictate the need for such a permit. The Air Quality Control Region may also have restrictions
on the types of process units and fuels that could be used. Local agencies may have permitting requirements for
construction activities (e.g., drilling and excavation), land treatment, and health and safety. In addition, if
wastewater is disposed via the sanitary sewer, the local water district effluent limitations and sampling
requirements must be met. Finally, state or local regulatory agencies may also establish cleanup standards for
the remediation.
At the Electro-Voice site, the operator was required to file an application for an air quality permit with
the Michigan DNR prior to receiving permission to release treated off-gases to the atmosphere. The operator was
never issued a formal permit but was required to submit an extensive contaminant dispersal model that calculated
anticipated concentrations of any vapor phase contaminants leaving EV property boundaries. Section 2 of this
report discusses the environmental regulations that might apply to this technology. Table 2-1 presents a summary
of the Federal and state ARARs for the SWS* vapor extraction/air sparging and in-situ bioremediation process.
5.2 Personnel Issues
The SWS*, once operational, can be run in a continuous mode and left unattended for progressively
longer periods of time. Installation of the SWS* (e.g., laying down reactor lines and drilling/installing vacuum
extraction and injection wells) has certain manpower requirements. The number of technicians and construction
equipment operators needed for construction of an SWS* depends on the size and design of a particular
installation. The manpower requirements for system installation at the Electro-Voice site included two
technicians, one field supervisor, and a two-man drill rig crew. The Electro-Voice design consisted of eleven
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vacuum extraction wells and nine injection wells installed alternately along three individually plumbed rows (i.e.,
reactor lines). Each reactor line was plumbed to a centrally located vapor control unit (VCU), which housed the
pumps, gauging, and emission control equipment. Conditions at the Electro-Voice site required the installation
of eight sand chimneys to facilitate vertical circulation through the sludge layer, thereby enhancing volatilization
>
and microbial activity within this zone. At least two technicians are required during system shakedown activities,
which are conducted to ensure that there are no air leaks in lines and valves and to optimize remedial stresses in
those areas that require it. The shakedown period is considered complete after one week of continuous operation.
Once the system is up and running it generally requires minimal attention. System maintenance activities were
performed once per week for the first month of operation, once per month for the following three months and then
once every three months for the remainder of the demonstration. Additional site visits might be required if
analytical and monitoring data suggest that further adjustments to the system are necessary for optimal
performance.
Personnel operating the SWS® are trained professionals with extensive knowledge and experience in
the complex conditions necessary to enhance the activity of the microbes responsible for VOC destruction.
SWS® personnel must have completed the OSHA-mandated 40-hour training course for hazardous waste work,
and have an up-to-date refresher certification. Personnel must also be enrolled in a medical surveillance program
to ensure that they are fit to perform their duties and to detect any symptoms of exposure to hazardous material.
5.3 Community Acceptance
Potential hazards to the community include exposure to volatile pollutants and other participate matter
released during system installation. These releases can be controlled by watering down the soils prior to any
excavation or drilling activities. In the application of any SVE technology, it is imperative that the system include
a properly engineered emission capture and treatment system to eliminate the generation of unacceptable fugitive
emissions. Noise may also be a factor for neighborhoods in the immediate vicinity of treatment. However, except
during system installation when heavy equipment is used, noise associated with the operation of the SWS® is
minimal.
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SECTION 6
TECHNOLOGY STATUS
This section discusses the experience of the developer/operator in performing treatment using the
SWS* vapor extraction/air sparging and in-situ bioremediation process.
6.1 Previous Experience
In addition to the technology demonstration, the SWS* has been employed at over 70 sites involving
petroleum hydrocarbon releases over the past five years. The soil and groundwater, including bulk product
accumulations, at several of these sites have been cleaned to applicable regulatory standards within this and
shorter time frames. The SWS® has also been implemented at sites in New Mexico, North Carolina, South
Carolina, Florida, Minnesota, West Virginia, Illinois, Michigan, Pennsylvania, Texas and England. Geological
conditions ranged through: elastics with hydraulic permeabilities of 10"' to 10 "* cm/sec; caliche deposits; karst
terrains, oolitic sands; active marine conditions; glacial deposits; shore deposits and fractured bedrock. In
addition to the solvents of this demonstration, the SWS* technology has proven useful on matrices contaminated
with BTEX, napthalenes, other PAHs, hydraulic fluid, #2 fuel oil, jet fuel, diesel, waste oil, kerosene, ethylene
dichloride, and ethylene dibromide.
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REFERENCES
Newman, W.A. and M.M. Martinson. 1992. "Let Biodegradation Promote In-Situ Soil Venting."
Remediation, Summer 1992. pp. 277-291.
Johnson, P.C. et al. 1990. "A Practical Approach to the Design, Operation, and Monitoring of In Situ
Soil-Venting Systems." Ground Water Monitoring Review, Spring 1990. pp. 159-178.
Johnson, P.C., M.W. Kemblowski, and J.D. Colthart. "Quantitative Analysis for the Cleanup of
Hydrocarbon-Contaminated Soils by In-Situ Soil Venting." Ground-water, May 1990. pp. 413-429.
Hinchee, R.E. and R.N. Miller. "Bioventing for hi Situ Treatment of Hydrocarbon Contamination."
Hazardous Materials Control, September 1990. pp. 30-34.
King Communications Group. 1994. "Billings and Associates Pioneer Air Sparging." The Bioremediation
Report, June 1994.
U.S. Environmental Protection Agency. 1993. Superfiind Innovative Technology Evaluation Program:
Technology Profiles; Sixth Edition. EPA/540/R-93/526. U.S. Environmental Protection Agency.
Office of Research and Development. Washington, D.C.
U.S. Environmental Protection Agency. 1991. "Feasibility Study Report: Electro-Voice Inc. Site."
WA 37-5PE8. Remedial Activities at Uncontrolled Hazardous Waste Sites in Region V.
U.S. Environmental Protection Agency. Washington, D.C.
U.S. Environmental Protection Agency. 1992. Record of Decision Summary: Electro-Voice Site.
U.S. Environmental Protection Agency, Region V. Chicago, Illinois.
Science Applications International Corporation. 1992. Subsurface Volatilization and Ventilation System™
Quality Assurance Project Plan, Second Revision. Science Applications International Corporation.
Hackensack, New Jersey.
Hinchee, R.E. and S.K. Ong. 1992. "A Rapid hi Situ Test for Measuring Aerobic Biodegradation Rates
of Hydrocarbons in Soil." Journal of the Air and Waste Management Association.
Michigan Department of Natural Resources. 1994. Guidance Document: Verification of Soil Remediation,
Revision I. Michigan Department of Natural Resources. Environmental Response Division. Waste
Management Division.
Michigan Department of Natural Resources. 1994. MERA Operational Memorandum #8, Revision 3 —
Type B Criteria Rules. Michigan Department of Natural Resources. Environmental Response
Division. February 1994.
Michigan Department of Natural Resources. 1994. Addendum to MERA Operational Memorandum #8,
Revision 3 - Type B Criteria Rules. Michigan Department of Natural Resources. Environmental
Response Division. June 1994.
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REFERENCES (Continued)
Science Applications International Corporation. 1994. Site Technology Capsule: Subsurface Volatilization
and Ventilation System™ (SWS™). Science Applications International Corporation. Hackensack,
New Jersey.
Fishbeck, Thompson, Carr & Huber. 1990. Final Remedial Investigation Report for Electro-Voice, Inc.
Fishbeck, Thompson, Carr & Huber. Ada, Michigan.
Halliburton NUS Environmental Corporation. 1992. SWS™ Bioremediation and Demonstration:
EPA/Electro-Voice Site. Halliburton NUS Corporation. Environmental Technologies Group.
Lansing, Michigan.
Mayotte, T. J. 1993. A Perspective on the Benefits of the Subsurface Volatilization and Ventilation
System™ for Promoting Rapid and Cost-Effective Remediation of Volatile Organic Contamination
in the Subsurface. Brown & Root Environmental. Holt, Michigan.
Halliburton NUS Environmental Corporation. 1992. SWS™ SITE Demonstration Work Plan. Halliburton
NUS Corporation. Environmental Technologies Group. Lansing, Michigan.
Brown & Root Environmental. 1993. An Evaluation of SWS™ Performance at the Electro-Voice Site in
Buchanan, Michigan. Brown & Root Environmental. Lansing, Michigan.
Ecology and Environment, Inc. 1991. Supplemental Risk Assessment for the Electro-Voice Site, Buchanan,
Michigan. Ecology and Environment, Inc. Lancaster, New York.
U.S. Environmental Protection Agency. 1993. Remediation Technologies Screening Matrix and Reference
Guide, Version I. EPA 542-B-93-005. U.S. Environmental Protection Agency. Office of Solid
Waste and Emergency Response. Technology Innovation Office. Washington, D.C.
Walpole, R.E. and R.H. Myers. 1978. Probability and Statistics for Engineers and Scientists, Second
Edition. Macmillan Publishing Co., Inc. New York.
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APPENDIX A
VENDOR'S CLAIMS
This appendix was generated and written solely by Brown & Root Environmental. The statements presented
herein represent the vendor's point of view and summarize the claims made by the vendor, Brown & Root
Environmental, regarding their SWS® process. Publication herein does not represent the EPA's approval or
endorsement of the statements made in this section; the EPA's point of view is discussed in the body of this
report.
A.1 INTRODUCTION
It has always been the goal to clean up sites contaminated with volatile organic compounds (VOCs) and semi-
volatile organics (SVOCs). Recently, however, there has been increased pressure to implement and complete
remediation of contaminated sites in a more timely fashion. Brown & Root Environmental is addressing this
challenge in many ways. One method is through the application of the patented Subsurface Volatilization and
Ventilation System (SWS®), an integrated process for the remediation of volatile organic compounds (VOCs)
and semi-volatile organic compounds (SVOCs) in soil and groundwater.
SWS takes advantage of liquid to gas equilibrium partitioning, or mass transfer, through the injection of air into
the saturated and/or vadose zones below the impacted subsurface materials, and the evacuation of vapors from
vertical wells or horizontal lines positioned at shallower depths. This circulation of air allows VOCs and, to a
lesser extend, SVOCs to be stripped from the groundwater, soil, and residual soil moisture due to their relatively
low aqueous solubilities and high vapor pressures. More importantly, however, the circulation of air increases
dissolved oxygen concentrations in the saturated zone, as well as soil moisture in the capillary fringe and vadose
zones. The increase in dissolved oxygen concentration serves to stimulate indigenous microbial activity, thereby
enhancing and accelerating bioremediation of organic compounds. Therefore, SWS* may be considered
primarily a bioremediation technology, which includes the added benefit of inducing contaminant mass transfer
and vapor withdrawal through the air circulation process.
An integrated treatment technology such as SWS*, which addresses contamination present in all four phases
(liquid product, dissolved, soil moisture and vapor), has many advantages over systems which address only one
or two phases of subsurface contamination. When a treatment system is designed to concentrate remediation in
only one phase of contamination (such as groundwater), the remaining phases of contamination will continue to
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be impacted by the phase which is being addressed. For example, pump-and-treat system applications focus on
remediation of groundwater, while contamination present in vadose zone soils may continue to act as a source.
This transfer between phases accounts for contaminant rebound during remediation. However, if all phases of
contamination are addressed simultaneously, as in the case of S WS*, remediation occurs faster, and without the
problems and lengthened remedial duration associated with contaminant rebound.
Using SWS®, the combination of mass transfer and enhanced bioremediation is quicker than bioremediation
alone, and the total quantities of VOCs that may need additional treatment are lower, than vapor extraction
technologies alone. The vapor extraction component destroys the easily-strippable VOC contaminants while the
bioremediation component targets the less volatile, more recalcitrant organics. As a result, the integrated SWS*
process can treat contaminants that would normally not be remediated by vapor extraction alone (such as
chemicals with lower volatility and/or chemicals that are tightly sorbed).
A.2 SWS® Applications
SWS* can be applied in most situations where subsurface VOC contamination is present. The primary limiting
factors, as in any remediation system, are soil type and the contamination present. To determine the effectiveness
of SWS* at a particular site, treatability testing is required to determine optimum design parameters for the
system. These parameters include, but are not limited to, the permeability of subsurface materials and the
characterization of the microbes that occur naturally in subsurface materials. Microbial specific parameters that
are helpful also include the optimum nutrient formulation (nitrogen, phosphorus, trace metals, etc.) for each
respective rnicrobial consortia, environmental conditions (pH, temperature, hardness, alkalinity, etc.), and the
possible toxicity/inhibitory effects of the organics on the respective biological cultures.
A.2.1 Geology/Hvdrologv Requirements
One of the most important factors affecting SWS* system design is the permeability of the soil. SWS* is most
effective in fine to medium sand deposits with permeabilities greater than l.Ox 1Q-* centimeters/second (cm/sec).
However, SWS* also has been applied with positive results at sites having deposits of silts and clays with
permeabilities less than 1.0 x 10* cm/sec. Coarse-textured soils that have a higher permeability allow higher flow
with the same induced vacuum than soils with lower permeabilities. In general, contamination that is present in
formations with low permeabilities (silts and clays) is remediated more slowly. This can be controlled by
adjusting certain design parameters such as system pump size and well spacing.
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A.2.2 Contaminants Amenable to the SWS® Process
The contaminants to be remediated must either have a vapor pressure suitable for mass transfer or must be
amenable to bioremediation. For dilute concentrations in water, Henry's Law Constants serve as a measure for
determining if the contaminant can be effectively stripped. Compounds with Henry's Law Constants greater than
2 x 1Q-3 atm-mVmol are considered to be amenable to SW5P . Removal efficiencies for these contaminants
generally range from 50 percent to greater than 90 percent.
In-situ microbes destroy the contaminants by converting them into carbon dioxide, water, and cell mass instead
of merely transferring the contaminants to a different media. Bioremediation also will remediate contaminants
that normally would not be remediated by vapor extraction alone (such as chemicals with lower volatility and/or
chemicals that are tightly sorbed). With conventional aerobic biological treatment systems, organic destruction
efficiencies can reach in excess of 99% if properly operated.
The SWS® process has been employed at over 70 sites of petroleum hydrocarbon compound releases over the
past five years. The soil and groundwater, including bulk product accumulations, at several of these sites have
been cleaned to applicable regulatory standards. In addition, SWS* has also been implemented to remediate
halogenated aliphatic compounds in the subsurface. The system has effectively treated low concentrations of
halogenated aliphatic compounds that are dense non-aqueous phase liquids (DNAPLs), including tetrachlorethane
and trichloroethene.
For higher concentrations of DNAPLs where free product may have accumulated above less permeable zones,
SWS® should also be effective. By creating a containment area through the horizontal and vertical placement
of air sparging wells, it may be possible to disperse DNAPL contamination within a controlled area. Dispersing
the DNAPL contamination will create low concentration zones that SWS* can effectively remediate. SWS*
well placement also can be designed to confine the DNAPL compound to a central area where it can be collected
from a recovery well.
A.3 SWS® Design
The design of SWS* allows for flexibility both in terms of system expansion and operation. Because of the
simplicity of system construction, and the reserve capacity of air injection and vapor extraction capabilities built
into a typical design, the system may be easily expanded. In addition, SWS* systems are operated in a dynamic
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fashion to .provide the most favorable in-situ conditions for the destruction of VOCs by the pertinent indigenous
microbes. The system not only allows for the delivery and circulation of air, and therefore oxygen, but also can
be modified easily to deliver certain nutrients necessary to optimize microbe viability.
A.4 Implementation
Installation of the SWS* system is flexible. In an effort to minimize costs and disruption of normal facility
operations, the installation is often coupled with previously scheduled site remodeling activities. Air injection
and vacuum extraction wells and reactor lines are installed in trenches approximately one foot wide and three feet
deep, making it possible to place plates over the trenches so that normal site activities can still be performed
during SWS* installation. The majority of SWS* installation activities are completed in one to two weeks.
A.5 Operations and Maintenance
Once the system is on-line, SWS* operations and maintenance (O&M) activities are less intensive than with
traditional treatment technologies. To optimize the performance of a typical SWS* system, data is collected and
adjustments are made once a week for the first three months. This is necessary because during the initial three
months significant reductions in subsurface contamination will be observed. In addition to optimizing system
operation, regulatory reporting (Air Use Permitting) may require adherence to this rigorous schedule during the
initial phase of remediation. In most applications, following the first three months of operation, O&M activities
can be reduced to once per month for the duration of the project.
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A.6 Costs
SVVS® is unique because the majority of costs associated with the remediation of a site are related to system
installation rather than labor intensive O&M activities. This is largely due to the relatively short remedial
duration, which usually ranges from 3 to 5 years.
The most significant costs associated with SWS® are system installation capital costs, such as pumps, the
treatment building, and the off-gas treatment system(s). Typical SWS* systems are installed and operated at
costs ranging between $100,000 and $250,000. Because of the flexibility of the system, the cost of SWS®
expansion is normally no greater than 10% to 20% of a project's total budget.
A.7 Evaluation of SWS®
SWS® is not a cure-all for all sites and situations. However, given suitable conditions, SWS* has been proven
to be a fast and effective method for soil and groundwater remediation.
A.7.1 Advantages
SWS® provides rapid, integrated remediation of contaminated soil and groundwater by synergistically combining
in-situ bioremediation and direct volatilization of contaminant removal from all affected media (the saturated
zone, the capillary fringe, and the vadose zone). SWS* is the most complete system for in-situ restoration of
contaminated soil and groundwater, with demonstrated success on more than 70 UST sites.
By removing hydrocarbons simultaneously from all affected phases, SWS* helps solve the problem of
groundwater re-contamination often associated with traditional pump and treatment technologies. SWS*
remediates the contaminated soil in the saturated zone, capillary fringe, and vadose zone directly, eliminating the
sources that might re-contaminate groundwater. In addition, the SWS* process can be applied to a wide variety
of sites contaminated with multiple VOCs and SVOCs in varying subsurface conditions. SWS* systems may
achieve site closure in significantly less time and at a lower cost than traditional pump and treat and soil vapor
extraction methods.
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It is an attractive option for effecting rapid cleanup in most subsurface conditions at a significantly reduced cost
compared to traditional remediation methods. In addition, SWS* presents a way for industry to minimize
liabilities through emphasis on contaminant destruction rather than transferral of VOC mass to another medium.
These facts emphasize that, at a minimum, consideration should be given to SWS* when assessing the technical
and economic feasibility of various remedial alternatives for addressing VOC and SVOC contamination in
subsurface materials.
A.7.2 Limitations
SWS* may not be an economically beneficial alternative for some remediation applications. For instance, when
remediating small, localized areas of contamination, the system installation capital costs may not be practical.
Also, when remediating subsurface materials having low permeabilities, an increased number of wells, larger
pump sizes, and longer remedial durations may increase system installation capital costs and O&M costs to the
point where it is not an economically beneficial alternative. In situations involving localized contamination and/or
subsurface materials with low permeabilities, a detailed cost analyses should be performed.
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APPENDIX B
CONVERSIONS
Mass
1 pound (lb) = 0.4536 kg
1 ton = 2,000 lb = 907.18 kg
1 kilogram (kg) = 2.20 Ib
Volume
1 cubic inch (in3) = 5.78E-04 ft3 = 2.14E-05 yd3 = 0.0164 L = 1.64E-05 m3 = 4.33E-03 ,
1 cubic foot (ft3) = 1,728 in3 - 0.0370 yd3 = 28.32 L = 0.0283 m3 = 7.48 gal
1 cubic yard (yd3) = 46,656 in3 = 27 ft3 = 764.55 L = 0.7646 m3 = 201.97 gal
1 cubic meter (m3) = 61,023 in3 = 35.31 ft3 = 1.31 yd3 = 1,000 L = 264.17 gal
1 liter (L) = 61.02 in3 = 0.0353 ft3 = 1.30E-03 yd3 = l.OOE-03 m3 = 0.2642 gal
1 gallon (gal) - 231 in3 = 0.1337 ft3 = 4.95E-03 yd3 = 3.7854 L = 3.79E-03 m3
Length
1 inch (in) = 0.0833 ft = 0.0278 yd = 0.0254 m
1 foot (ft) = 12 in = 0.3333 yd = 0.3048 m
1 yard (yd) - 36 in = 3 ft = 0.9144 m
1 meter (m) = 39.37 in = 3.28 ft = 1.09 yd
Temperature
1 degree Fahrenheit (°F) = 0.5556°C [x°C=0.5556 * (y°F-32)]
1 degree Celsius (°C) = 1.8°F [x°F=1.8 * (y°C)+32]
Pressure
1 pound per square inch (psi) = 27.71 in 1^0 = 6894.76 Pa
1 inch of water (in H20) = 0.0361 psi = 248.80 Pa
1 Pascal (Pa) = 1.45E-04 psi = 4.02E-03 in H20
Viscosity
1 poise = . 1 kg/m-sec = 2.09E-03 Ib/ft-sec
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1 kg/m-sec = 10.00 poise = 2.09E-03 Ib/ft-sec
llb/ft-sec = 478.70 kg/m-sec
Rate
llb/hr = 2.20kg/hr
Ikg/hr = 0.4536 Ib/hr
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'U.S. GOVERNMENT PRINTING OFFICE: 1995- 653-292
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