EPA/540/R-94/510
JULY 1995
Hughes Environmental Systems, Inc.
INNOVATIVE TECHNOLOGY EVALUATION REPORT
NATIONAL RISK MANAGEMENT RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
Printed on Recycled Paper
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NOTICE
The information in this document has been prepared for the U.S. Environmental Protection Agency
(EPA) Superfund Innovative Technology Evaluation (SITE) Program under Contract No. 68-CO-
0048. This document has been subjected to EPA's peer and administrative reviews and has been
approved for publication as an EPA document. Mention of trade names or 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 these mandates, 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 groundwater; 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 RiskManagement Research Laboratory
in
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TABLE OF CONTENTS
Section
Page
NOTICE ii
FOREWORD iii
LIST OF TABLES vii
LIST OF FIGURES viii
LIST OF ACRONYMS AND ABBREVIATIONS ix
ENGLISH TO METRIC CONVERSION FACTORS xi
ACKNOWLEDGEMENTS xii
EXECUTIVE SUMMARY 1
SECTION 1 INTRODUCTION 5
1.1 Background 5
1.2 Brief Description of Program and Reports 6
1.3 Purpose of the Innovative Technology Evaluation Report 9
1.4 Technology Description 9
1.5 Key Contacts 15
SECTION 2 TECHNOLOGY APPLICATIONS ANALYSIS 17
2.1 Objectives—Performance versus ARARs 17
2.2 Operability of the Technology 26
2.3 Applicable Wastes 29
2.4 Key Features 30
2.5 Availability/Transportability 31
2.6 Materials Handling Requirements 32
2.7 Site Support Requirements 33
2.8 Ranges of Suitable Site Characteristics 34
2.9 Limitations of the Technology 35
SECTION 3 ECONOMIC ANALYSIS 37
3.1 Conclusions of the Economic Analysis 37
3.2 Basis of the Economic Analysis 40
3.3 Issues and Assumptions 42
3.4 Results of the Economic Analysis 45
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TABLE OF CONTENTS (CONTINUED)
Section Page
SECTION 4 TREATMENT EFFECTIVENESS 64
4.1 Background 64
4.2 Testing Methodology 67
4.3 Performance Data 70
4.4 Residuals 87
SECTION 5 OTHER TECHNOLOGY REQUIREMENTS 90
5.1 Environmental Regulation Requirements 90
5.2 Personnel Issues 91
5.3 Community Acceptance 92
SECTION 6 TECHNOLOGY STATUS 94
6.1 Previous/Other Experience 94
6.2 Scaling Capabilities 94
6.3 Other Information 95
REFERENCES 96
APPENDIX A Case Study: Dynamic Underground Stripping Process at
Lawrence Livermore National Laboratory 97
VI
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LIST OF TABLES
Table Page
Table ES-1 Evaluation Criteria Results for In Situ SERP at the Rainbow Disposal Site 4
Table 2-1 Federal and State ARARs for the Steam Enhanced Recovery Process 19
Table 3-1 Summary of Results of the Economic Analysis 38
Table 3-2 Details of the Economic Analysis 46
Table 4-1 TPH and TRPH Results for Post-Treatment Soil 71
Table 4-2 Results of Triplicate Analyses for TPH and TRPH 72
Table 4-3 Percent Removal from Borehole Pairs 75
Table A-l Post-Treatment Analytical Results for Borehole #105 100
Table A-2 Post-Treatment Analytical Results for Borehole #106 100
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LIST OF FIGURES
Figure Page
Figure 1-1 The Layout of Injection and Extraction Wells at the Rainbow Disposal Site .12
Figure 1-2 Aboveground SERF Treatment Train 14
Figure 3-1 Approximate Actual Cost per Cubic Yard for Rainbow Disposal 39
Figure 4-1 Pre- and Post-Treatment Sampling Locations at the Rainbow Disposal Site ... 65
Figure 4-2 Histogram of Pre- and Post-Treatment TPH Concentration Data 76
Figure 4-3 Temperature Monitoring Well Locations 78
Figure 4-4 Soil Temperature Plot for Well Location 15 79
Figure 4-5 Soil Temperature Plot for Well Location 23 79
Figure 4-6 Soil Temperature Plot for Well Location 24 80
Figure 4-7 Soil Temperature Plot for Well Location 27 81
Figure 4-8 Soil Temperature Plot for Well Location 30 82
Figure 4-9 Soil Temperature Plot for Well Location 33 83
Figure 4-10 Soil Temperature Plot for Well Location 20 84
Figure 4-11 Well Water Usage and Diesel Recovered at the Rainbow Disposal Site 85
Figure A-l Approximate Locations of Process Wells and Sampling Boreholes
at the LLNL Site 98
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LIST OF ACRONYMS AND ABBREVIATIONS
ARAR applicable or relevant and appropriate requirement
BTEX benzene, toluene, ethylbenzene and xylenes
BTU British thermal unit
CAA Clean Air Act
CERCLA Comprehensive Environment Response, Conservation and Liability Act of 1980
CERI Center for Environmental Research Information
CFR Code of Federal Regulations
CWA Clean Water Act
DNAPL dense non-aqueous phase liquids
FID flame ionization detector
GC gas chromatography
GPM gallons per minute
in situ in place
LEL lower explosive limit
LLNL Lawrence Livermore National Laboratory
LUFT Leaking Underground Fuel Tank
MCL maximum contaminant level
MCLG maximum contaminant level goal
MS matrix spike
MSD matrix spike duplicate
NAAQS National Ambient Air Quality Standards
NIOSH National Institute for Occupational Safety and Health
NPDES National Pollutant Discharge Elimination System
NPL National Priority List
ORD Office of Research and Development
OSHA Occupational Safety and Health Administration
OSWER Office of Solid Waste and Emergency Response
PEL permissible exposure limit
POTW publicly-owned treatment works
ppb parts per billion
PPE personnel protective equipment
ppm parts per million
psi pounds per square inch
QA quality assurance
QAPP Quality Assurance Project Plan
QC quality control
RCRA Resource Conservation and Recovery Act
RREL Risk Reduction Engineering Laboratory
RWQCB Regional Water Quality Control Board
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LIST OF ACRONYMS AND ABBREVIATIONS (CONTINUED)
SAIC Science Applications International Corporation
SARA Superfund Amendments and Reauthorization Act
SCAQMD South Coast Air Quality Management District
SCFM standard cubic fset per minute
SDWA Safe Drinking Water Act
SERF Steam Enhanced Recovery Process
SITE Superfimd Innovative Technology Evaluation
SVOCs semivolatile organic compounds
TDS total dissolved solids
TOU thermal oxidation unit
TPH total petroleum hydrocarbons
TRPH total recoverable petroleum hydrocarbons
USEPA United States Environmental Protection Agency
VOCs volatile organic compounds
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ENGLISH TO METRIC CONVERSION FACTORS
To Obtain (metric unit) Multiply (English unit) by Conversion
meters feet 0.305
liters gallons 3.79
cubic meters (m3) cubic yards (yd3) 0.764
dollars per cubic meter ($/m3) dollars per cubic yard ($/yd3) 1.31
kilograms pounds (mass) 0.454
Note: To convert °F to °C use °C = (°F-32)(0.56)
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ACKNOWLEDGEMENTS
This project was directed and coordinated by Mr. Paul de Percin, the EPA SITE Technical Project
Manager in the Risk Reduction Engineering Laboratory (RREL) in Cincinnati, Ohio. It was prepared
for the EPA SITE Program under the direction of Mr. Kyle Cook of Science Applications
International Corporation (SAIC) under Contract No. 68-CO-0048. Major contributors from SAIC
were Ms. Ruth Alfasso, Mr. Raymond Martrano, Ms. Maria Marquez, Ms. Julie Poust, Mr. Jonathan
Rochez, and Ms. Jamie Winkelrnan. Dr. Trevor Jackson, Dr Victor Engleman, and Mr. Joseph Evans
of SAIC provided technical review.
EPA-RREL reviewers for this report were Ms. Michelle Simon and Ms. Naomi Barkley. Their
assistance in the preparation of this final report is greatly appreciated.
The cooperation and participation of Mr. W. Ron Van Sickle of Hughes Environmental Systems, Inc.
throughout the course of the project and in review of this report is gratefully acknowledged. Special
thanks are also offered to Mr. John F. Dablow III, formerly of Hydro-Fluent, Inc., and Mr. Richard
Timm of the Rainbow Disposal Company
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EXECUTIVE SUMMARY
This report summarizes the findings of an evaluation of the in situ Steam Enhanced Recovery
Process (SERF). This technology was operated by Hughes Environmental Systems, Inc. at the
Rainbow Disposal site in Huntington Beach, California. The Rainbow Disposal site is an active
municipal trash transfer facility that was contaminated by a spill of diesel fuel from a crushed
underground pipeline. The evaluation of this technology was conducted under the U.S.
Environmental Protection Agency (EPA) Superfund Innovative Technology Evaluation (SITE)
Program in conjunction with a full-scale remediation using SERP at the Rainbow Disposal site.
The EPA SITE Program evaluated the SERP technology to develop full-scale process
performance and cost data. The critical objectives for the Demonstration of the SERP technology
were: (1) to evaluate the ability of the technology to meet the cleanup requirement set by the
Regional Water Quality Control Board for the site soil, based on soil sampling results, and (2)
to perform a detailed economic analysis of this full-scale application of the technology.
Conclusions from the SITE Demonstration
Based on the SITE Demonstration, the following conclusions can be drawn about the in situ
SERP technology as applied to the Rainbow Disposal site remediation:
• The Demonstration results showed that the removal of contamination by the SERP
technology was less complete than expected. Forty-five percent of the post-
treatment soil sample results inside the treatment area were above the cleanup
criterion (1,000 mg/kg [ppm] of total petroleum hydrocarbons, or TPH). Seven
percent of the soil samples had TPH levels in excess of 10,000 mg/kg.
• A geostatistical analysis of the post-treatment soil data was conducted using a
computerized model to assess the spatial variability of soil contamination and to
determine a weighted average concentration of the soil sample results. From the
geostatistical model, a post-treatment weighted average soil concentration of
2,290 mg/kg of TPH with standard error of 784 mg/kg was derived. Based on an
approximate normal distribution for the weighted average, the 90 percent
confidence interval for TPH concentration is 996 mg/kg to 3,570 mg/kg. This
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large interval is attributed to the variability of site soil sampling results due to the
heterogeneity of the in situ soil contamination; analytical variability was within
established quality control limits and contributed little to overall data variability.
According to this analysis, at 90 percent confidence, the true average is probably
higher than the cleanup criterion of 1,000 mg/kg.
The geostatistical analysis results for total recoverable petroleum hydrocarbons
(TRPH) yielded a weighted average post-treatment soil concentration of 1,680
mg/kg with a standard error of 608 mg/kg. The 90 percent confidence interval
for the weighted average for TRPH is 676 mg/kg to 2,680 mg/kg. No cleanup
criteria were set for TRPH. The TRPH analysis provides information similar to
TPH but is performed using an EPA-approved method; the TPH method is widely
used but is not an EPA-approved method.
BTEX compounds were detected at low mg/kg levels hi a few pre-treatment soil
samples and were found at levels below the detection limit (6 Mg/kg) in all post-
treatment samples. Based on these results, the SERP technology may have
effected removal of BTEX compounds from the in situ soil, but this is
inconclusive due to the lack of positive BTEX results and the heterogeneous
nature of in situ soil contamination at the site.
Based on the weighted averages for the pre- and post-treatment soil data sets
determined from geostatistical analysis, the technology may have removed 40
percent of the contamination from the site soil. Due to the high site soil
contamination variability, at 90 percent confidence, the actual percent removal
may have been significantly higher or lower. Calculation of percent removal was
a secondary objective of the technology evaluation because pre-treatment data
were collected by the developer before the initiation of a SITE Program
Demonstration Quality Assurance Project Plan (QAPP).
Process data collected during treatment support the finding of a low to moderate
removal efficiency. Approximately 700 gallons of diesel were collected in liquid
form during treatment, while approximately 15,400 gallons were oxidized in the
system's vapor treatment equipment. Therefore, a combined total of
approximately 16,000 gallons of diesel were removed during treatment with
SERP. Compared to the estimated initial diesel spill volume of 70,000 to 135,000
gallons, this represents a reduction of approximately 12 to 24 percent. This
estimated removal is within the percent removal confidence interval for the soil
data.
The technology experienced significant amounts of downtime during treatment.
All major equipment systems experienced problems during treatment. An on-line
factor of 50 percent was experienced at this site for the technology application
over the two years of treatment. Reliability in subsequent applications of the
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technology is expected to be higher since this was the first full-scale application
of the technology.
• Based on soil temperature profiles from several areas of the site, heating of the
soil took much longer than originally anticipated and high soil temperatures were
not maintained in many areas. This may have been due to the way the process
was operated initially (16 hours per day, 5 days per week) and to excessive
operational downtime. The heating rate improved later in the application when the
process" operation went to a 24-hour per day, 6-day per week cycle. These
operational factors may have contributed to the failure of the SERF technology
to achieve the cleanup criterion for the site. More constant process operation and
monitoring should improve the performance of this technology in subsequent
applications.
• The costs for use of the technology at this site were relatively low; however, site
remediation did not achieve the cleanup criterion. Actual costs at the Rainbow
Disposal site were estimated to be approximately $46/cubic yard. A 50 percent
on-line factor was determined for this case. Under idealized conditions at this
site, which assumes a 100 percent on-line factor, the technology could have cost
as little as $29/cubic yard. For a site similar to the Rainbow Disposal site, under
typical operating conditions (on-line factor of 75 percent), the cost for use of
SERF was estimated to be $36/cubic yard. The large amount of soil treated by
the technology at the Rainbow Disposal site contributed to a relatively low cost
per cubic yard. The cost for use of the technology is most sensitive to the
duration of remediation, and start-up and utilities costs.
The in situ SERF technology was evaluated based on the nine criteria used for decision-making
in the Superfund Feasibility Study process. Table ES-1 presents the results of the evaluation.
Another in situ steam technology, the Dynamic Underground Stripping Process, was
demonstrated and evaluated by the Lawrence Livermore National Laboratory in conjunction with
the University of California at Berkeley, College of Engineering. The results of this evaluation
are presented in a case study in Appendix A of this report. The EPA SITE Program had limited
participation in the evaluation of this in situ steam technology, which is similar to the in situ
SERP discussed in this ITER.
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Table ES-1. EVALUATION CRITERIA RESULTS FOR IN SITU SERF AT THE RAINBOW DISPOSAL SITE
CO
5
E>
C/5
CRITERIA
Overall
Protection of
Human Health
and the
Environment
Reduced soil
concentrations
without excava-
tion
May reduce the
mobility of
contamination
into groundwater
after treatment
Did not appear to
cause lateral or
downward
migration of
contaminants
Compliance
with ARARs
Did not meet
soil cleanup
criterion, on the
average, in this
application
Less soil is
excavated, thus
less soil requires
disposal
Permits for
drilling,
operating, and
air and water
discharges are
required
Long-term
Effectiveness
and Permanence
A portion of
contaminants are
permanently
removed from
the soil
Removed
contaminants
can be
incinerated or
recycled
Residual
contamination
presents reduced
risk
Reduction of
Toxicity, Mobility
or Volume Through
Treatment
Treated soil had
lower concentra-
tions overall, some
areas were cleaned
to well below the
cleanup criterion
Remaining
contaminants may-
be less mobile
Lower soil
concentrations are
amenable to natural
or enhanced
biodegradation
Technology
residuals are not of
large volume as
compared to the
treated soil volume
Short-term
Effectiveness
Soil is treated
below ground so
potential air
emissions are
minimized
Other activity can
continue at
surface of
treatment area
with minor
disruption
Drilling and
treatment may
cause emissions,
noise and dust
which can be
mitigated
Implementability
Technology uses widely
available construction
and process equipment
Most regulatory permits
are common and are
readily acquired for
fuel-related cleanups -
Treatment of sites with
other contaminating
chemicals may require
additional permitting
requirements
Operational problems
can occur that may
delay the
remediation
The technology may not
be able to meet stringent
cleanup requirements,
necessitating post-
processing such as
assisted biodegradation
Cost
Ranged from
$29 "to $46
per cubic
yard for a
large site
Capital
equipment,
start-up, and
utilities costs
are high
Remediation
time is the
major factor
in the costs
Because the
process
operates in
situ, off-site
disposal costs
are minimized
State
Acceptance
Minimizes
excavation of
and exposure to
contaminated
soil
Potential exists
for off-site
subsurface
migration of
steam and
contaminants
Air emission
permit may be
required
Wastewater
discharge
permits may be
required
Community
Acceptance
Site
disturbance
can be
minimized
Does not
require major
interruptions
of existing
operations
May recover
product for re-
use or
recycling
May exceed
noise limits in
some areas
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SECTION 1
INTRODUCTION
This section provides background information about the SITE Program, discusses the purpose
of this Innovative Technology Evaluation Report (ITER), and describes the in situ Steam
Enhanced Recovery Process (SERF) technology that was evaluated. For additional information
about the SITE Program, the technology, and the Demonstration site, key contacts are listed at
the end of this section.
1.1 BACKGROUND
In August of 1991, a site remediation using the in situ SERF process was started at the Rainbow
Disposal site, an active municipal trash transfer facility in Huntington Beach, California. The
site had been contaminated by a leak of diesel fuel from an underground pipeline used to supply
fuel for trash trucks and other vehicles. SERP was selected by Rainbow Disposal, Inc. as a
cleanup remedy for the contaminated soil based on a site-specific feasibility study. SERP was
selected over other technologies since it required less excavation of soil, could be conducted
during continuing operations on the site, and could be used beneath existing structures.
The full-scale remediation at the Rainbow Disposal site was seen by the SITE Program as an
excellent chance to test the performance of the technology and to develop operating costs. The
SITE Program became involved with the technology at the Rainbow Disposal site when it was
being developed by Hydro-Fluent, Inc. Hydro-Fluent, Inc. ceased business operations in
September of 1991. Hughes Environmental Systems, Inc. took over the contract and continued
to operate the technology until the remediation was stopped in August 1993.
Pre-treatment sampling and analysis of the soil at the Rainbow Disposal site was conducted in
September 1991 by the technology operator with oversight from the EPA SITE Program, but
prior to full SITE Program involvement with the project. Post-treatment sampling and analysis
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was conducted in August and September of 1993 by the SITE Program using full quality
assurance procedures.
SERF operates on contaminated soil in situ through wells constructed in the ground. Steam is
injected into the soil through injection wells which are screened hi the contaminated depth or
depths. Extraction wells are operated using a vacuum to draw the steam, water, and
contaminants from the soil and into an aboveground treatment system. Contaminant removal
occurs below the soil surface, and, as was true at Rainbow Disposal, operations on the site
surface can continue with minimal interruption.
SERF is similar in concept to several other in situ technologies including vacuum extraction and
soil flushing. SERF differs from conventional in situ technologies in that it uses both steam
injection and extraction of vapor and liquids under vacuum. The added heat from the steam is
expected to increase the speed of remediation and make the technology more applicable to higher
boiling point (less mobile) compounds that cannot be removed by other in situ technologies such
as vacuum extraction or soil flushing
Another steam injection technology is the Dynamic Underground Stripping process used at the
Lawrence Livermore National Laboratory (LLNL), which uses electrical heating hi addition to
steam injection/vacuum extraction to increase removals of contaminants from low-permeability
soils. This technology was recently demonstrated and evaluated by LLNL in conjunction with
the University of California at Berkeley, College of Engineering. Appendix A to this ITER
presents a case study of the Dynamic Underground Stripping process. The EPA SITE Program
had a minor role in the evaluation of this technology.
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
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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 objective of the Demonstration Program is to develop 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 the
performance of the technology, the potential need for pre- and post-treatment processing of
wastes, potential operating problems, and the approximate costs. The Demonstrations also allow
for evaluation of long-term risks and operating and maintenance costs.
The Emerging Technology Program focuses on successfully proven bench-scale technologies that
are in an early stage of development involving pilot- or laboratory-scale testing. Successful
technologies are encouraged to advance to the Demonstration Program.
Existing technologies which 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 about innovative
technologies in the Demonstration, Emerging Technology, and Monitoring and Measurements
Technologies Programs through various activities. These activities increase the awareness and
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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.
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
technologies are of particular interest.
Once EPA has accepted a proposal, a cooperative agreement between EPA and the developer
establishes 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 the SERP Demonstration are published in two basic documents: the SITE
Technology Capsule and this Innovative Technology Evaluation Report (ITER). The SITE
Technology Capsule provides relevant information about the technology, emphasizing key
features of the results of the SITE field Demonstration. Both the SITE Technology Capsule and
the ITER are intended for use: by remedial project managers making a detailed evaluation of the
technology for a specific site and waste. A companion document to the ITER, called the
Technical Evaluation Report (TER) is published in limited quantities in unbound form. The TER
contains raw data from the testing and evaluation, and other information on which the ITER is
based. The TER is primarily designed to allow a quality assurance evaluation of the ITER.
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1.3 PURPOSE OF THE INNOVATIVE TECHNOLOGY EVALUATION REPORT
This ITER provides information about the SERF technology and includes a comprehensive
description of the SERF Demonstration and its results. It is intended for use by EPA remedial
project managers, EPA on-scene coordinators, contractors, and other decision-makers for
implementing specific-remedial actions. The ITER is designed to aid decision-makers in further
evaluating specific technologies for further consideration as an applicable option 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 and performance of each technology to specific sites and wastes. This ITER
includes information on cost and site-specific characteristics. 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, 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 for which the technology will perform
satisfactorily. Only limited conclusions can be drawn from a single field Demonstration.
1.4 TECHNOLOGY DESCRIPTION
SERP is an in situ process designed to remove volatile and semivolatile organic contamination
using steam to provide heat: and pressure. The process is applicable to the treatment of
contaminated soils and groundwater.
The process works by injecting high quality steam through wells (injection wells) constructed
to a depth at or below the contamination at a site. Additional wells (extraction wells) are
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operated under vacuum to create a pressure gradient in the soil to draw the liquids, vapor, and
contaminants through the soil. Liquid and vapor streams removed by the extraction wells are
directed to an aboveground liquid and vapor treatment system.
The geology of the site is influential in determining whether SERF will be applicable. There are
several site requirements for. effective operation:
• The contamination must consist of volatile and/or semivolatile compounds, such
as those found hi spilled fuel contamination.
• The soil must: have moderate to high permeability.
• The subsurface geology must provide a confining layer below the depth of
contamination. This layer can take three forms: (1) a continuous low permeability
layer such as a clay layer; (2) a water table, for compounds with liquid phases
lighter than water and low solubility; or (3) a continuous high permeability strata
filled with steam prior to treatment of the contaminated depth, for compounds
with boiling points lower than that of water [1].
• A low permeability surface layer may be needed to prevent steam breakthrough
for shallow treatment applications.
The removal of volatile and semivolatile contamination from the soil by SERF is effected by
several mechanisms. The high-quality, high-temperature steam (at approximately 250°F) heats
the soil mass to the steam temperature in a pattern radiating from the injection wells toward the
extraction wells, following the pressure gradients applied to the soil. As the soil heats,
contaminants which have boiling points lower than that of water will vaporize. The vapor will
then be pushed ahead of the steam front by the difference in pressure. Since the steam front
moves through the soil faster than heat can be conducted, the temperature gradient just ahead
of the steam front is steep. The vaporized contaminants move into the cooler soil and condense
until the steam front arrives. This results in a band of liquid contaminant that is formed just
ahead of the advancing steam. When the steam front reaches an extraction well, the vapor,
liquid, and contaminants are removed.
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Compounds with boiling points higher than that of water will not totally vaporize ahead of the
steam front. However, the introduction of steam and heat onto the soil matrix enhances the
vaporization and removal of these compounds due to the increased vapor pressure along with
the increase hi temperature.
Organic contaminants- in soil will collect on the surface of the mineral particles due to
intermolecular forces. The energy derived from the condensation of the steam onto the soil may
be sufficient to release these adsorbed contaminants and allow them to be removed by the flow
of steam and liquids.
The Rainbow Disposal site was contaminated by a spill of diesel fuel, which is primarily
composed of longer chain hydrocarbon compounds (8 or more carbon atoms). Diesel
compounds, although less dense than water, are heavier than those in most other petroleum-
based fuels (e.g., gasoline or jet fuel) and are consequently less volatile and more viscous. These
properties make diesel a more difficult contaminant to remove from the soil than most other
petroleum-based fuels.
SERF was applied to a treatment area at the Rainbow Disposal site covering a lateral area of
approximately 2.3 acres. The developer designed the system of process wells to treat the entire
area concurrently. Thirty-five (35) steam injection wells and 38 vapor/liquid extraction wells
were constructed in the treatment area. The wells were placed in a repeating pattern of four
injection wells surrounding each extraction well. The well configuration at the Rainbow Disposal
site is shown in Figure 1-1.
The distance between adjacent injection well/extraction well pairs on this site was approximately
45 feet; between adjacent wells of the same type, the spacing was approximately 60 feet. Well
spacing for a site is determined based on the permeability of the soil in the treatment area, the
size of the area, and the depth and concentration of the contaminants.
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^ ^( —""•-— J.J •'-"•" - J-T . ' ^ J[ "- j^ ' ""I
^ i—m 1
Figure 1-1. Layout of Injection and Extraction Wells at the Rainbow Disposal Site
The injection wells were constructed to a depth of 40 feet and slotted over the lower ten feet.
The extraction wells were screened from the bottom of the shallowest clay layer (approximately
ten feet below the soil surface) to two feet into the B aquitard (a total depth of approximately
35 feet). Piping was used to conduct the steam flow to the injection wells and to extract the
liquids and vapors from the wells. Well heads and pipe on the active portion of the Rainbow
Disposal site were installed in trenches below the ground surface. The trenches were backfilled
and metal plates were used to cover the piping and backfill to protect the pipes from pressure
12
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caused by truck traffic on the surface. Some of the process wells were installed beneath the
concrete floor of the service shop building.
Figure 1-2 is a schematic of the aboveground treatment system for steam generation and liquid
and vapor treatment. Water from a nearby deep well was pumped to a water softening system
for conditioning. The. softened water was directed through a heat recovery heat exchanger
designed to pre-heat the boiler feedwater while also cooling the liquids removed from the
extraction wells. Two chemical additives, a polymer dispersant and an oxygen scavenger, were
mixed with the feedwater to protect the boilers from scaling and corrosion. The pre-heated water
was then fed to one of two boilers on the site (only one boiler was used at a time). Steam at
approximately 15 pounds per square inch (psi) was produced by the boiler and injected into the
soil through the injection wells.
The liquid and vapor were removed from the extraction wells using pumps and compressors.
The liquid was pumped back through the heat recovery heat exchanger to be cooled by the boiler
feedwater. Vapor from the extraction wells was directed to a knock-out pot which removed
entrained particles and liquid. The liquid from the knock-out pot was then combined with the
liquid from the extraction wells in an oil/water separator. A condenser, fabricated of copper
piping placed in a large water bath, was constructed during the remediation to cool the liquid
from the knock-out pot and enhance the operation of the oil/water separator. The oil/water
separator was designed to remove the diesel compounds from the water by gravimetric
separation. The water phase discharged from the separator was treated by filtration and carbon
adsorption before being discharged to a storm sewer. The diesel phase (recovered product) was
collected in a 4,000-gallon tank for recycling or disposal off-site.
The vapor from the knock-out pot was directed to the thermal oxidizing unit (TOU). The TOU
is a self-contained regenerative vapor incineration system that used electric power and ceramic
rods to heat a bed of gravel-sized rocks to destroy the organic compounds in the vapor stream.
The TOU was designed to effect greater than 99.99 percent destruction and removal efficiency
of the organic compounds in the gas stream. The gas exiting the TOU was exhausted to the
13
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Water
ifteners
i
Softened Water /• tal
Heat Recovery
Heat Exchangers
WeU Water Stack
TlAir Cooled
OHeat Exchanger
^\
r \
1
P^-^l n ' ' n *H~
Natural Gas
From City
O
""i^n
D
High Quality
n*om
Boiler Feed Tank '
Steam Boiler
ned Vapor
A
Vacuum
Blower
Thermal Oxidizer Unit ' * "T
Zondensate
Micron
Filters
Knock-Out ^—
urum ^*
V
Contaminant Vapor
Treated Water
"T-^To Storm Drain
Oil/Water 4,000 gallon Tank Holding Tank Carbon
Separator (Recovered Diesel) (Separated Water) Filters
Deep
Water
Well
-j
LEGEND b
Vapor Stream •
^^^^^^^^^1 Well
Oily Water
(Hot)
T
Injection
Well
Figure 1-2. Aboveground SERF Treatment Train
atmosphere. A Ratfisch flame ionization detector and a lower explosive limit meter were
connected to the inlet of the: TOU to measure the concentration of total hydrocarbons being
burned and to ensure that safe operating conditions were maintained hi the unit.
The aqueous phase from the oil/water separator was discharged to the water treatment system,
which used 5-micron filters and activated carbon beds to remove residual organics to meet
NPDES permit requirements for discharge to the storm sewer. The spent carbon and filters were
containerized in appropriate drums and sent off-site for disposal when spent. Other residuals
from the process included excess soil from boreholes drilled for wells or sampling, and used
disposable clothing and equipment.
14
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1.5 KEY CONTACTS
Additional information on in situ steam technologies and the SITE Program can be obtained from
the following sources:
Potential Contractor for Thermal Enhanced Soil and Groundwater Remediation
John F. Dablow III
Groundwater Technology, Inc.
741 East Ball Road
Suite 103
Anaheim, CA 92805
(714)991-7112
FAX: (714) 991-8805
Hughes Environmental Systems, Inc. is no longer vending the SERP technology for use at other
sites.
Information on the Dynamic Underground Stripping Process at Lawrence Livermore
National Laboratory
Dr. Roger Aines
Earth Sciences Department
Lawrence Livermore National Laboratory
7000 East Avenue, Mail Stop 219
Livermore, CA 94550
(510) 423-7184
FAX: (510) 422-0208
The SITE Program
Robert Olexsey
Director, Superfund Technology Demonstration Division
U.S. Environmental Protection Agency
26 West Martin Luther King Dr.
Cincinnati, OH 45268
513-569-7861
FAX: 513-569-7620
15
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Paul de Percin
EPA SITE Project Manager
U.S. Environmental Protection Agency
26 West Martin Luther King Dr.
Cincinnati, OH 45268
513-569-7797
FAX: 513-569-7620
Information on the SITE Program is also available through the following on-line information
clearinghouses:
• The Alternative Treatment Technology Information Center (ATTIC) System
(operator: 301-670-6294) is a comprehensive, automated information retrieval
system that integrates data on hazardous waste treatment technologies into a
centralized, searchable source. This database provides summarized information
on innovative treatment technologies.
• The Vendor Information System for Innovative Treatment Technologies (VISITT)
(hotline: 800-245-4505) database contains information on 154 technologies offered
by 97 developers.
• The OSWER CLU-IN electronic bulletin board contains information on the status
of SITE technology Demonstrations. The system operator can be reached at 301-
585-8368.
Technical reports may be obtained by contacting the Center for Environmental Research
Information (CERI), 26 West Martin Luther King Drive in Cincinnati, Ohio, 45268. The
telephone number is 513-569-7562.
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SECTION 2
TECHNOLOGY APPLICATIONS ANALYSIS
This section of the report addresses the general applicability of the SERF technology to
contaminated sites. The analysis is based primarily on the SITE Program SERF Demonstration
results. Additional data from bench-scale and pilot-scale studies of the process have been used
where applicable.
2.1 OBJECTIVES-PERFORMANCE VERSUS ARARS
Under the Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA), as amended by the Superfund Amendments and Reauthorization Act of
1986(SARA), remedial actions undertaken at Superfund sites must comply with federal and state
(if more stringent) environmental laws that are determined to be applicable or relevant and
appropriate requirements (ARARs). ARARs are determined on a site-specific basis by the
remedial project manager. They are used as a tool to guide the remedial project manager toward
the most environmentally safe way to manage remediation activities. The remedial project
manager reviews each federal environmental law and determines if it is applicable. If the law
is not applicable, then the determination must be made whether the law is relevant and
appropriate. For example, a requirement under the Resource Conservation and Recovery Act
(RCRA) is to provide secondary containment for hazardous waste storage tanks. In the process
of treating fuel-contaminated soil using SERP, liquid product is extracted. The extracted fuel
product must be stored in a tank. The storage tank would not be considered a hazardous waste
storage tank, as defined by RCRA, since fuel is not hazardous waste. However, RCRA's
secondary containment requirements for hazardous waste storage tanks may be relevant and
appropriate.
17
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A discussion of the federal and state environmental laws that are applicable or relevant and
appropriate to SERF follows. A table of ARARs as they relate to the process activities conducted
at the Rainbow Disposal site for the SERF technology is presented in Table 2-1.
2.1.1 Comprehensive Environmental Response, Compensation, and Liability Act
CERCLA authorizes the EPA to provide liability, compensation, cleanup, and emergency
response for hazardous substances released into the environment and the cleanup of inactive
hazardous waste disposal sites. Facilities become "Superfund sites" when they have been listed
on the National Priorities List.
SARA directed the EPA to use remedial alternatives that permanently and significantly reduce
the volume, toxicity, or mobility of the contamination; select remedial actions that are
protective, cost-effective, and involve alternative treatment technologies to the maximum extent
possible; and avoid off-site transport and disposal of untreated hazardous substances.
The Rainbow Disposal site is not a Superfund site; however, CERCLA/SARA is relevant and
appropriate for the treatment technology occurring on-site. Using the SERP technology at the
Rainbow Disposal site met all of the SARA criteria. It was an in situ treatment technology, thus
the treatment process occurred in place and the removal of the contamination was permanent and
protective to human health arid the environment; the volume and mobility of the waste diesel in
the soil was reduced; SERP was cost-effective and an alternative treatment technology; and, as
stated above, untreated waste was not transported off-site for disposal. Also the extracted
contaminants could potentially be concentrated and reused on-site as a fuel supplement or
transported off-site for fuel recovery. Unfortunately, the treatment technology did not meet the
cleanup standard imposed by the California Regional Water Quality Control Board (1,000 mg/kg
total petroleum hydrocarbons as diesel).
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Table 2-1. FEDERAL AND STATE ARARS FOR THE SERF TECHNOLOGY
Process Activity
Waste characterization
of untreated waste
Drilling activities
related to well
installation
1 1 —
Waste processing using
SERF technology
Cleanup standards are
established
ARAR
RCRA: 40 CFR 261
OSHA: 29 CFR
1910.120
RCRA: 40 CFR 264
Subpart J and 270 (or
State Equivalent;
RCRA: 40 CFR 266
Subparts D or E. and
H
CAA: 40 CFR 50, and
52 (Subpart F)
SDWA: 40 CFR 144
and 146 Subpart F
SARA Section
121(d)(2)(A)(ii);
SDWA: 40 CFR 141;
H&SC Chapter 6.75
LUFT
Description
Untreated waste should be characterized to determine if it is a
hazardous waste, and if so, if it is a RCRA-listed waste.
Personnel need to be protected from volatile emissions and
airborne particulates during soil boring activities. Personnel need
to be provided with protective equipment and be involved in a
medical monitoring program.
Treatment of a RCRA hazardous waste requires a permit. If
non-RCRA waste, then a permit or a variance from the State
hazardous waste agency may be required.
Hazardous waste and oil burned for energy recovery must meet
the reporting and record keeping requirements. Permits arc
required for hazardous waste burned in boilers and industrial
furnaces.
Emissions from vapor treatment system must be monitored to
meet NAAQS; air permit may be necessary.
Injection of steam requires a Class V permit.
Remedial actions of surface and groundwater are required to
meet MCLGs (or MCLs) established under SDWA. Corrective
actions of leaking underground fuel tanks in California must be
consistent with waste discharge requirements.
California Regional Water Quality Control Board establishes
clean up standards for fuel-contaminated soil and water using a
decision matrix found in the LUFT.
Comment
Applicable
Provide air monitoring
equipment during drilling;
Use a fan to keep
personnel upwind of
vapors.
If activity is conducted
within one year on
remediation wastes, full
RCRA permit may not be
required.
Applicable
Applicable
Applicable
Applicable for surface and
groundwater; Relevant and
appropriate if drinking
water source could be
affected.
Applicable, relevant and
appropriate.
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Table 2-1. (Continued)
Process Activity
ARAR
Description
Comment
Storage of waste
RCRA: 40 CFR Part
264 Subpart J (or State
Equivalent)
Storage tanks for recovered liquid waste (i.e., recovered diesel)
must be placarded appropriately, have secondary containment,
and be inspected daily.
If storing non-RCRA
wastes, RCRA
requirements are still
relevant and appropriate.
RCRA: 40 CFR Part
264 Subpart I (or State
Equivalent)
Containers of contaminated soil from soil borings and process
stream residuals (separator sludge, filters) need to be labeled as
a hazardous waste, the storage area needs to be in good
condition, weekly inspections should be conducted, and storage
should not exceed 90 days unless a storage permit is acquired.
Applicable for RCRA
wastes; relevant and
appropriate for non-RCRA
wastes.
Waste Disposal
K)
O
RCRA: 40 CFR Part
262
Generators of hazardous waste must dispose of the waste at a
facility permitted to handle the waste. Wastes generated include
soil cuttings and recovered product. Generators must obtain an
EPA ID No. prior to waste disposal.
Applicable
CWA: 40 CFR Parts
403 and/or 122 and
125
Discharge of wastewaters to a POTW must meet pre-treatment
standards; discharges to a navigable water must be permitted
under NPDES.
Applicable
RCRA: 40 CFR Part
263; HWCA: H&SC
Chapter 13
Hazardous wastes transported off-site for treatment or disposal
must be accompanied by a hazardous waste manifest. Hazardous
waste haulers operating in California must be registered with the
State and inspected by the California Highway Patrol.
Applicable
RCRA: 40 CFR Part
268
Hazardous wastes must meet specific treatment standards prior
to land disposal, or must be treated using specific technologies.
Applicable
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2.1.2 Resource Conservation and Recovery Act
As opposed to CERCLA, RCRA regulates solid and hazardous wastes managed (generated,
treated, stored, and disposed of) at operating facilities to minimize the need for corrective action
in the future. Wastes are defined as RCRA hazardous wastes if they meet one of the
characteristics (toxic, ignitable, corrosive, or reactive) as discussed in 40 CFRPart 261 Subpart
C, or if they are listed in 40 CFR Part 261 Subpart D. RCRA contains specific requirements for
any unit managing hazardous wastes including proper labeling, condition of containers, and
secondary containment. In addition, RCRA contains specific requirements for personnel handling
hazardous waste including training, inspections, medical monitoring, and record keeping. In
1984, RCRA was amended by the Hazardous and Solid Waste Amendments which added
requirements for corrective action and restrictions on land disposal.
The SERF technology can treat RCRA-listed wastes containing volatile and semivolatile organics
in soil. After treatment, the extracted liquid waste must meet specific treatment standards prior
to being land disposed. The waste would need to be transported off-site to a permitted treatment
facility or treated on-site. If treated on-site, the facility would require a RCRA permit. Under
the corrective action regulations, a treatment unit used to treat "remediation wastes" may not
require a full RCRA permit if that treatment activity occurred in one year or less. RCRA wastes
generated during SERF treatment may include extracted waste, contaminated filters,
contaminated activated carbon, and wastewater; these must be transported off-site for further
treatment and disposal. In some cases, the recovered product could be used as a fuel for the
steam generation system. In this case, the standards applicable to units burning hazardous waste,
or oil, for energy recovery apply, 40 CFR 266, Subparts D or E.
The Rainbow Disposal site is not a RCRA facility in that it does not manage RCRA wastes. In
addition, the released diesel product and the waste streams generated during the SERF treatment
process are not RCRA wastes since 40 CFR 261.4 exempts releases from underground storage
tanks undergoing corrective action from the RCRA regulations. Thus, the diesel waste would
21
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not be required to be disposed of at a RCRA hazardous waste facility. However, RCRA is an
appropriate and relevant requirement. The 4,000-gallon diesel tank should have secondary
containment. Drums of soil cuttings should be leak-free and marked with the contents and the
date of accumulation.
2.1.3 Clean Air Act
The Clean Air Act 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 emissions of hazardous air pollutants, including vinyl chloride, arsenic, asbestos, and
benzene. States are responsible for enforcing the Clean Air Act. In so doing, Air Quality Control
Regions were established. If necessary, and for purposes of efficiency and effectiveness, an Air
Quality Control Region may be broken up into Air Quality Management Districts. The Air
Quality Control Region establishes allowable emissions, on a site-specific basis, depending upon
whether or not the site is locaited within an air basin in attainment with the National Ambient Air
Quality Standards (NAAQS).
The SERF technology extracts volatile and semivolatile organics from soil in both liquid and
gaseous forms. NAAQS for nitrogen oxides and carbon monoxide and emission standards for
benzene may be applicable to the SERF technology's vapor treatment system and steam
generation system; thus, an air permit from the Air Quality Control Region may be required.
In addition, any unit that may emit a pollutant to the air during normal operations requires an
Authority to Construct permit. In order to operate the unit, a Permit to Operate must be
obtained.
The Rainbow Disposal site is located within the South Coast Air Quality Management District
(SCAQMD) hi Orange County, California. Orange County is in non-attainment status for all
primary and secondary air quality standards except sulfur dioxide. Emission standards were
established by the SCAQMD for the thermal oxidizer unit: benzene in the exhaust stream (0.041
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pounds per day); volatile organic compounds in the inlet stream (4,200 ppmv); and hydrocarbon
vapors in the outlet stream (5 percent of the inlet stream).
2.1.4 Clean Water Act
The objective of the Clean Water Act is to restore and maintain the chemical, physical, and
biological integrity of the nation's waters. To achieve this objective, effluent limitations of toxic
pollutants from point sources were established. Publicly-owned treatment works (POTW) can
accept wastewaters with toxic pollutants from facilities; however, pre-treatment standards must
be met and a discharge permit may be required. A facility desiring to discharge water to a
navigable waterway must apply for a permit under the National Pollutant Discharge Elimination
System (NPDES). When a NPDES permit is issued, it includes waste discharge requirements.
Since water is extracted along with the organic contamination using SERP, waste water must be
properly managed. Depending on the type of contaminant and the facility at which the
technology is being employed, three options are open for water disposal: off-site disposal at a
RCRA treatment facility; discharge through a sanitary sewer under an industrial pre-treatment
permit; and discharge to the waterways of the United States under a NPDES permit. Wastewater
generated at the Rainbow Disposal site using the SERP technology was first polished in an
activated carbon system and then discharged to the storm sewer system under NPDES permit
number CA 8000176.
2.1.5 Safe Drinking Water Act
The Safe Drinking Water Act establishes primary and secondary national drinking water
standards to protect human health and the public welfare. The drinking water standards are
expressed as the maximum contaminant levels for the various constituents. Under SARA Section
121(d)(2)(A)(ii), remedial actions of groundwater and surface water are required to at least meet
the standards of the maximum contaminant level goals (MCLGs) if they are relevant and
appropriate. MCLGs have been established for several organic, inorganic, and microbiological
23
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contaminants. Some MCLGs for organic compounds capable of being remediated by SERF
include toluene (1 mg/L), xylene (10 mg/L), and ethylbenzene (0.7 mg/L). For contaminants
with MCLGs set at 0 mg/L,, the maximum contaminant level (MCL) for that constituent must
be attained when groundwater or surface water is remediated. MCLs for contaminants capable
of being remediated by SERF include vinyl chloride (0.002 mg/L), benzene (0.005 mg/L, and
trichloroethylene (0.005 mg/L). Since some contamination may remain in the soil after
remediation with SERF which may reach groundwater, a regulatory agency may require that
MCLGs or MCLs, as appropriate, be used as standards for determining if the remedial action
met its pre-specified cleanup criteria.
Although groundwater treatment was not evaluated at the Rainbow Disposal site, MCLGs may
be appropriate and relevant action levels for ascertaining a successful remediation of the site,
should contaminants remain hi the soil that could potentially leach to the groundwater. Benzene,
toluene, xylene, and ethylbenzene (BTEX) were constituents of interest at the Rainbow Disposal
site. During pre-treatment soil sampling, toluene and xylene were detected at low concentrations.
Post-treatment soil samples had non-detectable concentrations.
The Safe Drinking Water Act also contains requirements for the Underground Injection Control
Program. Any operator injecting water underground must first obtain approval from the
authorized State agency. No underground injection authorization can be granted if it results in
any of the following: a fluid containing any contaminant moves into underground sources of
drinking water, a contaminant causes a violation of the primary drinking water standards, or a
contaminant adversely affects human health. Underground injection wells are divided into five
classes. Class V wells are those not covered by Classes I through IV and include injection wells
used in experimental technologies. Criteria and standards applicable to Class V injection wells
can be found in 40 CFR Part 146, Subpart F.
The SERP technology injects steam, thus the wells used for this purpose would fall under the
requirements of the Underground Injection Control Program. Steam injection wells would
24
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require a Class V permit. The primary drinking water standard that would have to be monitored
is total dissolved solids (must be less than 10,000 mg/kg).
2.1.6 Occupational Safety and Health Act
CERCLA remedial actions.and RCRA corrective actions must be conducted within the
requirements of the Occupational Safety and Health Act. Personnel working at a hazardous waste
site are required to complete a 40-hour initial training, 3-day on-site supervised training, and
annual 8-hour refresher courses. Personnel must also be in a medical monitoring program that
first establishes a medical baseline. Annual monitoring is performed to determine if an individual
was exposed to hazardous substances or conditions. Requirements are also established for
confined space entry, trenching and shoring, and personnel protective equipment such as steel-
toed boots, hard hats, and hearing protection.
2.1.7 California Hazardous Waste Control Act
California's Hazardous Waste Control Act, included hi the Health and Safety Code, Sections
25000 et. seq., is comparable to RCRA in many ways. California's hazardous waste regulations
are promulgated in Title 22, California Code of Regulations. The similarities include waste
management requirements, handling requirements, training, inspections, and emergency planning
requirements. However, there are differences which make the Hazardous Waste Control Act
more stringent. One difference is how California regulations define a waste as hazardous.
Certain wastes are hazardous hi California and not considered hazardous under RCRA. These
include waste oil, asbestos, PCBs, and waste fuels (including diesel). Treatment of these wastes
would be considered a hazardous waste treatment requiring a hazardous waste facility permit.
Also, tank systems holding more than 5,000 gallons of a hazardous waste are defined as storage
tanks and require a hazardous waste storage permit. California offers variances from the
permitting requirements if a facility is treating a non-RCRA waste and meets specific
requirements.
25
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The SERF technology treats hazardous waste in that it removes the hazardous constituents from
the soil and concentrates them. A hazardous waste permit may be required unless the treatment
occurs as part of a CERCLA remediation activity or a RCRA corrective action (lasting less than
one year).
2.1.8 California Petroleum Underground Storage Tank Cleanup Act
Chapter 6.75 of the Health and Safety Code, Petroleum Underground Storage Tank Cleanup,
was added in 1989 to address corrective action pertaining to leaking underground fuel tanks. The
statute requires corrective actions to be consistent with applicable waste discharge requirements
or other applicable state policies for water quality control.
2.1.9 California Leaking Underground Fuel Tank Field Manual
The Leaking Underground Fuel Tank (LUFT) field manual was prepared by a multiagency task
force involving personnel from the California Department of Toxic Substances Control,
California Department of Health Services,, California State Water Resources Control Board,
California Regional Water Quality Control Boards, and various County Health Departments. The
LUFT field manual was created to provide guidance for regulatory agencies responsible for
dealing with leaking fuel tank problems. The primary jurisdiction for overseeing cleanups of fuel
from underground tanks lies with the California State Water Resources Control Board. Using
this manual, the California Regional Water Quality Control Boards set cleanup standards for
petroleum-contaminated soil and water. The Regional Water Quality Control Board established
a 1,000 mg/kg cleanup limit for diesel (total petroleum hydrocarbons) hi soil and 100 mg/L limit
for diesel in groundwater for the Rainbow Disposal site.
2.2 OPERABBLITY OF THE TECHNOLOGY
Because SERP operates on contaminated soil in situ, the use of the technology is site-specific.
The size of the site, the type of contamination and its extent, the geology, and the geographical
26
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location all influence the suitability of the technology, the way the technology is implemented,
and the effectiveness of the technology on treating the waste. The Rainbow Disposal site had
several features which determined the method by which the technology was implemented. A
discussion of some of those characteristics and their effects follow.
The site is approximately 2.1 acres in size, which posed logistical challenges during installation
and operation. The size of the site required a large number of injection and extraction wells (73
total) for complete coverage, at a well spacing of 45 feet between each injection well and the
nearest extraction wells. Well installation and maintenance was more difficult because most of
the well heads in the active area were installed below grade and under metal plates. While this
configuration allowed operation of the transfer facility to continue without major interruption,
downtime for SERF was increased when problems could not be detected or repaired as quickly
as they might be otherwise.
The underground conditions influenced design requirements. This included the depth and interval
of contamination. Process wells (injection and extraction) were constructed to 40 feet deep. The
injection wells were screened in the contaminated sand zone between approximately 35 and 40
feet. Extraction wells had 25-foot screens. The site geology was not constant over the entire
treatment area. The same alternating layers of sand and clay which directed the flow of
contamination in the site soil also influenced the treatment process. Removal of contamination
trapped in the less permeable clay layers was difficult because the steam and heat could not
penetrate these areas easily and flow patterns could have been developed which bypassed less
permeable areas altogether.
Underground utilities and other objects were present in the treatment area. While the technology
was capable of treating around the obstructions, some of them posed specific challenges. Early
in the treatment process, steam became channeled into a gravel conduit for the phone cables on
the site, leading to steam breakthrough hi an on-site utility shed. The treatment process was shut
down while the damage was repaired and the water was removed. Several underground fuel
tanks were present in the middle of the treatment area. Because these tanks contained residual
27
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fuel, the technology operator had to be careful not to expose them to excessive heat. Extra
temperature monitoring probes were placed near the tanks, and the injection wells nearby were
kept turned off until late in the treatment process, The result was that the area either reached the
steam temperature late in the process or not at all; therefore, those areas were probably not
effectively treated.
No vapor condensation system was designed and included in the aboveground treatment system.
Most of the contamination removed from the site by the SERF technology remained in the vapor
phase during treatment in the aboveground treatment process. Only about 4,700 gallons of diesel
were collected in the aboveground storage tank during treatment according to measurements
taken by the developer. About 4,000 gallons of this was free product that was removed from
some of the wells before treatment with SERF commenced. It is estimated that at least 15,400
gallons of removed diesel were oxidized in the TOU during treatment with SERF.
Although the treatment system was initially designed to operate for only eight months, treatment
operations occurred for a period of two years. Several factors were responsible for the large
increase in operating time. Knowledge of the process was limited prior to remediation at the
Rainbow Disposal site, and no application of this size had been designed or attempted. For
example, the operators learned from the process that more time would be needed to heat and
remediate the site. Major and minor operational problems that stopped or slowed operation were
also quite common during treatment. Both boilers experienced frequent and sometimes lengthy
breakdowns. The TOU required frequent service and could take more than a day to return to
operating temperature after repair. During the winter of 1991-1992, both boilers were shut down
for a period of more than two months due to operational and structural problems. This long
shutdown probably allowed the site to cool considerably and, therefore, delayed the treatment
even further. Process operation changed in October 1992, from a 16-hour per day, five days per
week cycle to a 24-hour per day, six days per week cycle. Operational efficiency for heating the
soil seemed to increase after this change, and more constant operation was felt to be less
stressful on the boilers and other components as well.
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Although some of the diesel contamination was removed from the soil, the process did not meet
the cleanup level of 1,000 mg/kg total petroleum hydrocarbons. This may be due to the factors
mentioned above. In the initial plan for treatment of the site, it was known that the technology
was not capable of removing all of the contamination from the site. It was believed, however,
that the cleanup level could be obtained rapidly, and the residual contamination would be low
enough for natural biodegradation to become effective.
2.3 APPLICABLE WASTES
According to the developer and operators of SERF, the technology can be applied to many in
situ contaminant situations. The contamination must consist of volatile and/or semivolatile
organic compounds. Because of the addition of heat (steam) to the soil, SERF is applicable to
compounds that are less volatile than those which would be removed solely by vacuum
extraction. Wastes containing a mixture of compounds of varying boiling points potentially can
be treated with this technology. For contaminants whose liquid phases have densities greater than
water (dense non-aqueous phase liquids or DNAPLS), too high an initial concentration could
result in downward migration of contamination when the liquid is concentrated in situ by the
process. The suggested upper concentration limit depends on the specific compound and ranges
from 200 to 1,000 mg/kg [1].
The primary contaminated matrix must be composed of soil; fractured rock or semisolid matrices
cannot be treated by this technology. Highly impermeable clay materials also may not be suitable
for SERP treatment. The technology is capable of treating soil with underground obstructions
such as buried tanks, utility lines, and buried rocks or debris. The location of such obstructions
should be determined to the greatest extent practical before treatment. Applying heat around
underground objects such as utility lines could cause damage. Contaminated groundwater can
be treated by the technology concurrently with the soil, or the treatment area may be dewatered
before treatment.
29
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The depth to the bottom of the treatment zone is not a significant limiting factor. The technology
has been used at a depth of over 100 feet at another site (see Appendix A for more information).
Applications of the technology in deeper soils may realize a significant cost advantage over
excavation, due to the difficulty in removing soils at greater depths.
Applicable waste requirements for this in situ technology also include requirements for the site
geology and geography. As described in Section 1.4, the site must have a lower confining layer
and may need an upper confining layer to control the steam and contaminant flow. Sites with
channels of permeable material (e.g., sand, utility trenches, loose debris) in a less permeable
matrix may cause channeling of the steam and limit treatment of other areas. A minimum
volume of contiguous waste is required for cost-effective operation. In general, this technology
is not economical for areas smaller than 1,000 square feet or those with contamination extending
to no more than 10 feet below the soil surface.
2.4 KEY FEATURES
The most obvious advantage to an in situ technology, such as SERF, is that little excavation is
required to treat the soil. Since the soil is treated in place, the waste is not subject to any land
disposal restrictions that might be applicable if excavation were required. This can reduce the
costs of cleanup by reducing the need for transportation and disposal of hazardous substances.
Additionally, because the soils are treated in place, the waste problem is not simply moved to
another location.
The developer claims that SERF offers advantages over other in situ technologies such as
vacuum extraction or soil flushing. High energy steam is used to treat the soil so that treatment
can be much faster and more complete than with just air or cold water. Higher boiling point
compounds can also be removed more readily using steam. Although the perched groundwater
table at the Rainbow Disposal site was depressed during free product recovery prior to treatment
with SERF, the developer clamed that contaminated groundwater could be treated concurrently
with the soils in the treatment area. This claim was not evaluated.
30
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The developer also claimed that SERF can effectively treat operating sites with minimal impact
to site operations. At the Rainbow Disposal site, the ability to treat soils under and around
existing structures was especially important to the site owners. On the active portion of the site,
process and monitoring wells were installed below grade under metal plates so that truck traffic
could continue unimpeded. Had large-scale excavation been required, the commercial activities
on the site would have been suspended, which was not acceptable to the site owners or the
serviced community.
2.5 AVAILABILITY/TRANSPORTABILITY
An expert in the field of SERF technology is required to design the system so that treatment
theory can be properly applied to subsurface characteristics. Most of the process can then be
constructed from off-the-shelf items. This allows the operator of the technology to estimate
construction costs accurately. Some of the aboveground treatment processes (e.g., condensers
and separators) must be sized and fabricated for the specific application. Temperature monitoring
probes and accessories may also require custom fabrication.
Since the process operates in place, each application uses a different configuration tailored to
the site size, geography, contaminant type, and other local factors. Key equipment includes well
casings and materials, water conditioning equipment, boilers, vacuum pumps, and wastewater
treatment equipment. The same aboveground equipment can be used to treat several sites in
succession; however, transportability depends on the size of the equipment. Well materials and
other below ground equipment such as temperature probes, however, are often not reusable once
they have been installed.
One developer of a technology similar to SERF is designing a transportable system to be used
with the technology. The transportable system will provide all the aboveground treatment
processes required for application of the technology (steam generation, wastewater treatment,
and vapor treatment). The size and other specifications of this transportable unit are not known
at this time. Portable systems employing steam injection to treat shallow fuel contamination have
31
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been used in the Netherlands since 1985 [2]. These systems include re-usable steam lances
instead of constructed injection wells.
2.6 MATERIALS HANDLING REQUIREMENTS
For SERF, materials handling equipment includes a variety of equipment required to install the
wells and other process equipment; handle water conditioning chemicals, maintenance materials,
and process wastes; and transport liquids and gases through the treatment system.
Boreholes for wells and for collecting soil samples are installed using a drill rig. Drilling
services are generally subcontracted to a company which has both the required equipment (e.g.,
drill rigs, augers, samplers) and personnel trained in drilling operations and well construction.
Drilling services are required at different times during the project, including pre-treatment
sampling, process installation, and post-treatment sampling.
A forklift was used at the Rainbow Disposal site for transporting bags of salt or other chemicals
to the water softeners; transporting drums containing drill cuttings, spent carbon or other wastes;
and transporting equipment, such as piping, during process installation. Depending on site size
and configuration, hand-powered equipment may be used exclusively or in addition to a forklift.
Pumps are used to transport the vapors and liquids away from the wells. Other pumps are used
within the system to convey well water and water treatment chemicals to the boilers and to drive
the wastewater through the treatment system. These pumps, especially the extraction well
pumps, must be able to perform under harsh conditions, including elevated temperature, high
solids content, and variable chemical concentrations. These factors should be taken into account
during the selection of pumps and ancillary equipment, such as hoses and fittings.
32
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2.7 SITE SUPPORT REQUIREMENTS
Access to utilities is required to use SERF on a site. Water is needed for producing steam. This
water must be of high quality, containing no contaminants that might further contaminate the
soil. Injectable water quality may be further determined by injection well permits.
Approximately 20,000 gallons of water per day were required at the Rainbow Disposal site.
Water usage is determined primarily by site size and volume of soil to be treated. SERF
operators at the Rainbow Disposal site were able to discharge the treated wastewater directly to
a storm sewer. Without a sewer connection, wastewater might need to be transported or piped
to another location for disposal.
Electricity is required to run pumps, other process equipment, lights, monitoring equipment, and
office equipment. At the Rainbow Disposal site, the boilers for steam production were fired by
natural gas. A high capacity natural gas line was brought to the site. If a gas line is not
available, other fuel may be substituted, depending on availability and air quality requirements.
Other support facilities for use of the technology would include concrete pads to support the
boilers and other process equipment, a building or trailer for use as office space, and a storage
building or trailer to store tools and equipment. A maintenance shop or area is also required.
Outdoor lighting may be necessary for 24-hour operations.
A relatively accessible site with good roads is required to bring in process equipment and other
heavy equipment, such as drill rigs and transport trucks. In addition, personnel must also be able
to get to and from the site readily for daily process monitoring and control. The entire site,
including all process wells, must be secured to prevent damage to the equipment and to minimize
hazards to unknowing trespassers or visitors. A fence and a locked gate were used at the
Rainbow Disposal site for security purposes. The Rainbow Disposal site also had 24-hour
security to protect the active commercial facility, and this assisted in protecting the SERF
equipment. Other sites may require a 24-hour guard depending on the application and site
location.
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2.8 RANGES OF SUITABLE SITE CHARACTERISTICS
Site characteristics which have not been included in Section 2.3, Applicable Waste, are discussed
below. SERF is suitable for operation in moderate climates. It may be suitable for use in cold
climates, but utilities or fuel consumption may be greater. Arid areas may also be prohibitive
unless there is a large, amount of water available for steam generation. System equipment can
be designed or modified to use available fuels, and also to operate in colder climates by using
insulation and shelter.
SERF is generally suitable for use in industrial areas and in areas with little habitation (such as
military bases). While the technology can be operated with a low profile, the potentially long
duration of treatment may not be acceptable in a residential setting since the process equipment
may be noisy and unsightly. Investment in equipment which minimizes noise and other nuisance
problems may allow use of this technology in almost any setting, although costs may be higher.
Because SERP is an in situ treatment technology, it may not be suitable for locations where there
are fragile geological structures or ecosystems. Permits for constructing and operating injection
wells may be difficult to obtain if there is any potential for negatively impacting usable water
bodies above or below the soil surface. It may not be desirable to operate the technology at sites
with certain toxic contaminants, such as dioxins, because of the chance of mobilizing these
contaminants and the difficulty or cost of disposing of the wastewater and residuals generated
from the process.
To treat shallow soils, an upper confining layer may be required so that steam does not exit
through the surface. If an adequate layer does not already exist on the site, a temporary cap of
asphalt could be placed on the site until treatment was completed.
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2.9 LIMITATIONS OF THE TECHNOLOGY
The main limitation of the SERF technology, as shown by this full-scale Demonstration, is that
it can be difficult to predict both how long the technology will need to be operated and how
complete the treatment will be. An initial treatment time of eight months was planned for the
Rainbow Disposal site, but the system was operated for two years (see Section 2.2, Operability).
During treatment with SERF, the operators monitored certain operational parameters to
determine the progress of treatment including soil and extraction well temperatures, and vapor
stream contaminant concentrations. According to these indicators, the rate of removal of
contamination from the soil was slow, thus extending the treatment time. The rate of removal
of contamination might have been much greater if the process had been operated more
continuously over the entire site.
Because the entire site is treated at once and in place, it is more difficult to test and adjust the
technology while it is operating, unlike a flow-through process where the impact of operational
changes can be determined more immediately. Additionally, plots of soil are generally not
homogeneous in either contamination or geology. Some areas of a site may be completely treated
while others are not, making it difficult to judge remediation progress. Proper monitoring of the
treatment is crucial to the application and success of the technology. Even when treatment is
effective, a certain amount of residual contamination is likely to remain in the soil.
The SERF equipment has a high capital cost. Some of the equipment is site-specific; it is
difficult to reuse wells and temperature probes purchased to remediate a site. Operation of SERF
requires trained personnel for operation of the boilers and for service and maintenance of the
equipment. Labor costs were determined to be the most significant of the twelve cost categories
investigated in the Economic Analysis found in Section 3 of this document.
After treatment with SERF is complete, the soil will remain at elevated temperatures for an
extended period of time. Soil is an excellent thermal insulator, and a large mass of moist soil
has a high capacity to retain heat. Data from models and from the application of SERF and
35
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similar technologies suggest that several years of cooling are required to bring the soil back to
ambient temperatures. High soil temperatures can pose a hazard during digging or construction
activities on the site and may delay any beneficial use of the site. The temperature of the soil
may also inhibit natural biodegradation of the residual contamination. Continued vacuum
extraction of the site long after the application of steam can potentially reduce the soil
temperature much more rapidly than conductive cooling alone.
36
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SECTION 3
ECONOMIC ANALYSIS
3.1 CONCLUSIONS OF THE ECONOMIC ANALYSIS
The results of the economic analysis are summarized in Table 3-1. The approximate total cost
for use of the full-scale SERF technology at the Rainbow Disposal site was about $4,401,120
over the two-year period of operation. This results in a cost of approximately $46 per cubic yard
for a site with 95,000 cubic yards of contaminated soil (see Section 3.3, Issues and
Assumptions). Figure 3-1 is a graphical representation of the costs per cubic yard, broken out
by cost category, for the actual case. Under ideal operating conditions, the remediation with
SERF at the Rainbow Disposal site might have cost about $2,789,910, or approximately $29 per
cubic yard. Based on available information, costs were also calculated for use of SERF at a
similar site of the same size and contamination profile under what might be considered "typical"
operating conditions. These costs were estimated to be about $3,375,910, or approximately $36
per cubic yard.
Labor is the largest cost for use of SERF, accounting for about one third of the total cost. Since
labor costs are directly proportional to the duration of remediation, factors which would increase
the remediation time would increase total costs the most significantly. Start-up costs and utilities
are also significant for use of SERF, together accounting for another third of the total costs. The
cost for natural gas accounted for more than ten percent of the total remediation costs. Cost
details are discussed further in the following sections.
As discussed in the Executive Summary, and in more detail in Section 4 of this report, SERF
did not meet the cleanup objectives set for the Rainbow Disposal site. At the time remediation
at the site was stopped, the operator believed that the process had gone nearly to completion
under the circumstances, and mat little additional removal would have occurred if treatment had
been continued. Continuing treatment would have increased the total cost and the cost per cubic
yard for the site, but it is impossible to determine what these costs would have been. It is
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Table 3-1. SUMMARY OF RESULTS OF THE ECONOMIC ANALYSIS
rime to Remediate {Days)
Assumed On-Lifle Factor
Site $&e (yd1)
Site Preparation Costs
Permitting and Regulatory Costs
Non-Depreciable Equipment Costs
Startup and Fixed Costs
Labor Costs
Consumables and Supplies Costs
Utilities Costs
Effluent Treatment and Disposal Costs
Residuals and Waste Handling and
Disposal Costs
Sampling and Analytical Costs
Facility Modification, Repair, and
Replacement Costs
Site Demobilization Costs
TOTAL COSTS
Approx. Actual Costs for
Rainbow Disposal
Total ($)
$/yds"
746
50%
$ 338,230
$ 16,100
$ 522,990
$ 758,800
$ 1,362,000
$ 43,430
$ 631,470
$ 71,100
$ 67,200
$ 299,900
$ 150,700
$ 139,200
$ 4,401,120
$ 3.56
$ 0.17
$ 5.51
$ 7.99
$ 14.34
$ 0.46
$ 6.65
$ 0.75
$ 0.71
$ 3.16
$ 1.59
$ 1.47
$ 46.33
Estimated Ideal Cost for
Rainbow Disposal
Total ($)
$/yd3**
373
100%
$5,000
$ 325,960
$ 11,100
$ 522,490
$ 413,500
$ 775,600
$ 24,320
$ 280,190
$ 35,600
$ 49,250
$ 195,900
$ 57,500
$ 98,500
$ 2,789,910
$ 3.43
$ 0.12
$ 5.50
$ 4.35
$ 8.16
$ 0.26
$ 2.95
$ 0.37
$ 0.52
$ 2.06
$ 0.61
$ 1.04
$ 29.37
Estimated Cost for a Typical
Site of the Same Size
Total <$)
S/yd3**
497
75*
$ 336,200
$ 14,100
$ 524,070
$ 435,700
$ 1,033,600
$ 32,420
$ 493,020
$ 47,400
$ 61,400
$ 221,900
$ 77,600
$ 98,500
$ 3,375,910
$ 3.54
$ 0.15
$ 5.52
$ 4.59
$ 10.88
$ 0.34
$ 5.19
$ 0.50
$ 0.65
$ 2.34
$ 0.82
$ 1.04
$ 35.54
* This table presents a summary of the detailed costs itemized in Table 3-2.
** For each cost category, costs per cubic yard are reported to the nearest cent.
38
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ED Facility Modification,
Repair, and
Replacement Costs
($1.58)
Residuals and Waste
Handling and Disposal
Costs ($0 71)
Site Demobilization
Costs ($1.47)
Sampling and Analytical
Costs ($3.15)
Effluent Treatment and
Disposal Costs ($0.75)
Utilities Costs ($6.65)
D Consumables and
Supplies Costs ($0.45)
HI Site Preparation Costs
($3.55)
Permitting and
Regulatory Costs
($0.17)
Non-Depreciable
Equipment Costs
($5.50)
D Startup and Fixed
Costs ($8.00)
H Labor Costs ($14.34)
All costs in U.S. Dollars.
Total cost per cubic yard: $46.32
Figure 3-1. Cost Per Cubic Yard Treated During SITE Demonstration
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possible that, had treatment been conducted with less downtime, the site would have been more
completely remediated in less time.
3.2 BASIS OF THE ECONOMIC ANALYSIS
This economic analysis is designed to conform with the specifications for an order-of-magnitude
estimate. This is a level of precision established by the American Association of Cost Engineers
(AACE) for estimates having; an expected accuracy within +50 percent and -30 percent. In the
AACE definition, these estimates are generated without detailed engineering data. Suggested uses
of these estimates are in feasibility studies or as aids in the selection of alternative processes [3].
Because the costs for use of SERP were derived from a post-mortem analysis of the treatment
over the two-year period, the costs are probably more accurate than these specifications,
especially for some cost categories. However, the applicability of these costs to other uses of
SERP at other sites is limited by the highly site-specific nature of the process and the associated
costs. Therefore, labeling these cost figures as "order-of-magnitude" estimates is appropriate.
3.2.1 Factors Affecting the Estimated Costs
The costs derived from the Rainbow Disposal SERP Demonstration are specific to this site only.
A detailed cost estimate of SERP for another site1 would involve designing a treatment system
to apply to that site, which is beyond the scope of this analysis.
Factors affecting the estimated costs include site soil type, site contamination characteristics, site
location, and volume and area of the contaminated soil. The impact of any of these factors on
the cost for using the technology can only be estimated based on available data. Soil type affects
how quickly the steam can penetrate the soil and how rapidly the contamination can be removed.
Less permeable soils, or areas of lower permeability within a more permeable matrix, can
require longer treatment times and consequently exhibit higher costs. Different contaminant types
or concentrations can influence the required treatment time; less volatile compounds are expected
to require longer treatment for removal. The type of contamination may also influence the types
40
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and amounts of waste products generated, types of effluent treatment required, and waste
disposal costs. Site location can affect the costs for labor, construction, utilities, and materials.
Climate can also affect the costs, both in the energy required to heat the soil and the design of
the necessary process and ancillary equipment. From examining costs for construction and
operation, it appears that more cost-effective operation can be achieved when the volume of
contaminated soil extends in depth as opposed to extending in surface area, since fewer wells
would be required.
3.2.2 Cost Data Categories
Cost data associated with SERF have been assigned to the following 12 categories: (1) site
preparation; (2) permitting and regulatory requirements; (3) capital equipment; (4) start-up and
fixed costs; (5) labor; (6) consumables and supplies; (7) utilities; (8) effluent treatment and
disposal; (9) residual waste shipping, handling, and disposal costs; (10) sampling and analytical
services; (11) maintenance and modifications; and (12) demobilization.
3.2.3 Cost Sources
Cost data for this economic analysis were derived from several sources. The technology operator
provided costs for equipment, labor, permitting, and demobilization. Other costs were derived
from vendors of supplies and equipment and from utility companies. During operation,
information on the use of utilities and supplies was collected, and operational logs were updated
daily. These data were used to calculate and estimate the costs for supplies and maintenance as
well as the on-line factor for the process. Costs for start-up, sampling and analysis, and
demobilization were derived from process diagrams and construction drawings as well as
information gathered by SAIC while conducting post-treatment sampling and analysis.
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3.3 ISSUES AND ASSUMPTIONS
3.3.1 Type of Cost Analyses Performed
An economic analysis for the SERF technology was performed for three cases. The first case
represents actual costs incurred at the Rainbow Disposal site over the two-year period of
remediation. The second case examined potential costs for idealized conditions at the same site,
while the third presents costs that could be expected at a site of the same size and contamination
profile under "typical" operating conditions.
The first cost analysis, termed the actual case, represents the approximate actual costs incurred
during the two-year remediation period (September 1991 to August 1993, a total of 746 calendar
days) at the Rainbow Disposal site. This case uses actual cost data from the operator whenever
available, utility rates and other cost information valid for Southern California during the period
of remediation, and estimated costs where necessary. Significant equipment downtime occurred
at the Rainbow Disposal site during remediation. For the actual case, an on-line factor of
approximately 50 percent was calculated based on operational logs and observations of the
process. For this cost case, monthly charges were based on a total of 25 months of operation,
and weekly charges were based on a total of 107 weeks.
The second cost analysis, termed the ideal case, is a study of the costs of the technology at the
Rainbow Disposal site for idealized conditions. These costs were based on use of the technology
without major operational problems or equipment failures, and therefore assume an on-line factor
of 100 percent. A remediation time of 373 (calendar) days was used for this cost case, half of
the actual case, based on the assumption that the treatment rate is proportional to the total days
of remediation only. This simplifying assumption was made although it is likely that, with a
complex in situ process such as this one, there is not a proportional relationship between the
percent of days that the equipment is in operation and the necessary duration of remediation.
Further examination of the required length of treatment is beyond the scope of this investigation.
The ideal case used the same cost rates as those incurred for the actual case at the Rainbow
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Disposal site, and costs associated with Southern California utilities, labor rates, and other
business factors. For this cost case, monthly charges were based on a total of 12 months of
operation, and weekly charges were based on a total of 53 weeks. Because this case is based on
the potentially unrealistic assumption that operation could occur without operational downtime,
it represents the lowest cost, or "best case" that could be achieved for the technology at the
Rainbow Disposal site and should therefore be considered a lower bound on the potential costs.
The third case suggests what costs would be incurred by using the technology at a site of the
same size and similar contamination profile at a non-specified location. This typical case includes
some equipment or process downtime, which might be expected during typical operations. This
case assumed an on-line factor of 75 percent and therefore an operational time of approximately
75 percent of the duration of the actual case (for a total duration of 497 calendar days). This on-
line factor was estimated based on knowledge of the process components and on lessons learned
during operation that will prevent or minimize the impact of some potential operating problems.
For this cost case, monthly charges were based on a total of 17 months of operation, and weekly
charges were based on a total of 71 weeks.
The typical case differs from the actual and the ideal case in that calculations use rates for
utilities, labor, and other cost factors that are based on a composite of those found in a selection
of metropolitan areas around the country, (e.g., gas and water rates were derived from those
currently charged in Boston, Massachusetts; Dallas, Texas; Miami, Florida; St. Louis, Missouri;
and Seattle, Washington) instead of those for Southern California. Although this cost case is not
directly comparable to the actual and the ideal cases, the application of the typical cost case
allows discussion of the effect of site location and other factors on the total costs for SERF.
Because the typical case utilized an on-line factor midway between those for the actual and ideal
cases, it represents a likely set of costs for the technology application. The application of this
case is explained more fully in subsections of Section 3.4.
Both the ideal case and the typical case assumed 24-hours-per-day operation, six days per week
during operation. The actual operation began with a 16-hours-per-day operation for the first year
43
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of treatment. When 24-hours-per-day operation was started, system efficiency appeared to
increase dramatically, with only moderate increases in costs. Less frequent shutdowns (weekly
rather than daily) are also believed to reduce wear on boilers and other equipment due to cycling
and thermal shock and to minimize blockage of process wells.
The three cost cases presented bracket a range of costs for similar sites over the expected range
of on-line factors. The actual case is seen as a "worst case" for costs due to the large amount
of operational downtime. Lessons learned from this application will assist in preventing
excessive downtime in subsequent applications. Since the technology is extremely site-specific,
actual costs will vary from these estimates. The effect of site size or contamination on the costs
for SERF are not considered due to the complexity of the process, although both factors are
expected to be important in both treatment effectiveness and total costs.
3.3.2 Other Assumptions
In addition to the assumptions described above, other general assumptions were used for each
of the cost cases:
• Legal fees, legal searches, and access rights and roads are the responsibility of
the site owner and are not included in remediation costs.
• Costs do not include profit.
• Extensive site characterization data, including the delineation of the size of the
contamination plume, types of contaminants, and basic site geology (for all cases)
were already available prior to the selection of SERF as the remedy. This limits
the need for technology-specific site characterization.
• The site size for all cost cases is the same. The treatment zone is 2.3 acres
(100,000 square feet) in area and encompasses a depth between 20 feet and 40
feet below the soil surface for a total volume of approximately 95,000 cubic yards
(2,565,000 cubic feet). This volume is used to calculate the cost per cubic yard
of soil treated.
• Costs for labor include wages, fringe benefits, and overhead charges.
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• All personnel required for the remediation, except the project manager and any
parent-company administration, are hired locally.
• High quality water is available for use with the technology.
• Clean drill cuttings from soil borings can be redeposited on the site rather than
disposed of off-site.
• The level of health and safety protection needed is minimal (level D) during
normal operations because the process occurs beneath the surface. Modified or
full level C protection may only be needed during drilling and sampling
operations. Higher levels of protection are not needed.
3.4 RESULTS OF THE ECONOMIC ANALYSIS
The detailed results of the economic analysis are shown in Table 3-2. Details on specific
subcategories of costs and the derivation of costs for each category are found in the following
text.
3.4.1 Site Preparation Costs
For use of an in situ technology such as SERF, a large proportion of the costs are incurred at
the start with the planning and preparation of the site and equipment. A SERF process well
system is built into the soil to be treated. Therefore, site preparation costs are a significant factor
in the total treatment costs.
Site preparation costs include the costs for designing the system (site design and layout), as well
as the aboveground systems to be installed. This was estimated, based on information supplied
by the operator, as requiring 2,500 hours of engineering time at $100 per hour plus
miscellaneous labor and other expenses ($20,000) for a total of $270,000. This cost was used
for all three cases. It can be assumed that treatment systems for smaller sites, or those with less
complex geology than at the Rainbow Disposal site, would be less costly to design.
45
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Table 3-2. DETAILS OF THE ECONOMIC ANALYSIS
Time to Remediate (Days)
Assumed Oa-Liae Factor
Site size (yd3)
SITE PREPARATION COSTS
Site Design and Layout
Site Survey and Investigation
Legal Searches
Access Rights and Roads
Preparation for Support Facilities
Auxiliary Buildings
Technology-Specific Requirements
Total Site Preparation Costs
PERMITTING AND REGULATORY COSTS
NPDES and Other Permits
Development of Monitoring Protocols
Total Permitting and Regulatory Costs
EQUIPMENT COSTS
Major Equipment2
Minor Equipment
Equipment Rental
Total Equipment Costs7
Total Non-Depreciable Equipment Costs
STARTUP AND FIXED COSTS
Equipment Installation
Shakedown
Working Capital
Depreciation
Insurance and Taxes
Initiation of Monitoring Program
Contingency
To^S^ajc^u£ ai^JwedjDpsts
Approximate
Actual Costs for
Rainbow Disposal
Total ($)
746
50%
$ 270,000
$ 39,100
$ 3,700
$ 8,930
$ 16,500
$ . 338,230
$ 10,000
$ 6,100
$•** «fuv
lO,l(JU
$ 402,000
$ 519,000
$ 3,990
$ 924,990
$ 522,990
$ 249,000
$ 52,800
$ 30,000
$ 362,000
$ 50,000
$ 5,000
$ 10,000
758,800.00
Estimated
Ideal Cost for
Rainbow Disposal
Total {$)
373
100%
95,000
$ 270,000
$ 39,100
Not applicable1
Not applicable1
$ 3,700
$ 4,660
$ 8,500
$ 325,960
$ 5,000
$ 6,100
$11 1AA
IJLfJLUv
$ 402,000
$ 519,000
$ 3,490
$ 924,490
$ 522,490
$ 249,000
$ 52,800
$ 30,000
$ 41,700
$ 25,000
$ 5,000
$ 10,000
413,500.00
Estimated Cost for
a Typical Site
of the Same Size
Total <$>
497
75%
$ 270,000
$ 39,100
$ 3,700
$ 14,900-
$ 8,500'
$ 336,200
$ 8,000
$ 6,100
$14 1AA
J.4,1UU
$ 402,000
$ 519,000
$ 5,070
$ 926,070
$ 524,070
$ 249,000
$ 52,800
$ 30.000
$ 55.6U)
$ 33.300
$ 5.000
$ 10.001)
435,700.00
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Table 3-2. (Continued)
Time to Remediate (Days)
Assumed On-Line Factor
Site size (yd3)
LABOR COSTS
Project Direction
Administration
Engineering/Technical
Maintenance
Clerical Support
Fetal Labor Costs
CONSUMABLES AND SUPPLIES COSTS
Water Softening Chemicals
Filters and Activated Carbon
Maint and Cleaning Materials
Monitoring Supplies
Health and Safety Supplies
Paper/Office Supplies
Total Consumables and Supplies Costs
UTILITIES COSTS
Natural Gas
Well Water
Electricity
Phone
Sewer
Total Utilities Cost$
EFFLUENT TREATMENT AND DISPOSAL COSTS
Treatment Equipment (See Equipment)
Filter & Carbon Replacement (See Supplies)
Sewer Discharge Costs (See Utilities)
Monitoring and Reporting Requirements
Total Effluent Treatirient and Disposal Costs
Approximate
Aciual Costs for
Rainbow Disposal
Total ($)
746
50%
$ 107,000
$ 38,100
$ 1,030,000
$ 79,900
$ 107,000
$ 1,362,000
$ 21,200
$ 8,600
$ 3,380
$ 2,250
$ 4,000
$ 4,000
$ 43,430
$ 527,000
$
$ 99,500
$ 4,970
$
$ 631,470
—
—
—
$ 71,100
$ 71,100
Estimated
Ideal Cost for
Rainbow Disposal
Total {$)
373
100%
95,000
$ 53,300
$ 16,000
$ 613,000
$ 40,000
$ 53,300
$ 775,600
$ 13,200
$ 4,300
$ 1,690
$ 1,130
$ 2,000
$ 2,000
$ 24,320
$ 228,000
$
$ 49,700
$ 2,490
$
$ 280,190
—
—
—
$ 35,600
$ 35,600
Estimated Cost for
a Typical Site
of the Same Size
Total {$)
497
75%
$ 71,000
$ 21,300
$ 817,000
$ 53,300
$ 71,000
$ 1,033,600
$ 17,600
$ 5,730
$ 2,250
$ 1,500
$ 2,670
$ 2,670
$ 32,420
$ 269,000
$ 21.400
$ 66.300
$ 3.320
$ 133.000
$ 493,020
$ 47.4OO
$ 47,400
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Table 3-2. (Continued)
rime to Remediate (Days)
Assumed Oa-Line Factor
Site size (yd1)
Approximate
Actual Costs for
Rainbow Disposal
Total {$)
746
50%
Estimated
Ideal Cost for
Rainbow Disposal
Total {$)
573
100%
Estimated Cost for
a Typical Site
of the Same Size
Total ($)
497
75%
95,000
RESIDUALS AND WASTE HANDLING AND DISPOSAL COSTS
Drill Cuttings
Liquid Wastes (product, sludge)
Other Wastes
total Residuals and Waste Handling and Disposal Costs
SAMPLING AND ANALYTICAL COSTS
Operational Analyses (see Effluent Treatment)
Environmental Monitoring, initial
Environmental Monitoring, periodic
Environmental Monitoring, confirmation
Total Sampling and Analytical Costs
$ 42,600
$ 7,500
$ 17,100
$ 67,200
$ 33,200
$ 7,500
$ 8,550
$ 49,250
$ 36,300
$ 7,500
$ 17,600
$ 61,400
—
$ 31,800
$ 209,000
$ 59,100
$ 299,900
—
$ 31,800
$ 105,000
$ 59,100
$ 195,900
—
$ 31,800
$ 131,000
$ 59,100
$ 221,900
FACILITY MODIFICATION, REPAIR, AND REPLACEMENT COSTS
Design Adjustments
Scheduled Maintenance
Equipment Replacement
Total Facility Modification, Repair, and Replacement Costs
$ 56,500
$
$ 94,200
$ 150,700
$ 20,600
$
$ 36,900
$ 57,500
$ 27,400
$
$ 50,200
$ 77,600
SITE DEMOBILIZATION COSTS
Site Restoration
Shutdown
Closure Permitting Costs
Removal of Equipment
Total Site Demobilization Costs
TOTAL COSTS
$ 92,000
$ 47,200
$ 92,000
$ 3,500
Not Applicable1
$
$ 139,200
$ 4,401,120
$ 3,000
$ 98,500
$ 2,789,910
$ 92,000
$ 3,500
$ 3,000
$ 98,500
$ 5,375,910
Not applicable: This cost is the responsibility of the site owner and is not included in this analysis.
Major Equipment costs are taken into account under depreciation and are used to estimate factors such as repair and modification
costs. They are not direct costs and are therefore excluded from the totals.
No direct maintenance costs have been used in this analysis. Costs for regular maintenance tasks are considered under labor
and supplies.
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Site surveying and investigation must be conducted to complete the design of the technology and
to assist in designing the environmental monitoring program. The scope of these activities is very
site-specific. The investigation at the Rainbow Disposal site included borehole drilling and
logging, sample analysis, and data interpretation. Since preliminary site investigation and
characterization occurred before the selection of SERF as a treatment technology, the cost for
site surveying and investigation included drilling costs for only ten boreholes. It was assumed
that thirty (30) soil and 30 groundwater samples from these boreholes were analyzed. Soil gas
probes were also utilized to complete the plume delineation. The total site surveying and
investigation costs were calculated to be approximately $39,100. Total costs for site design and
layout, as well as site surveying and investigation, were assumed to be the same for all three
cost cases.
Preparation for support facilities included grading, location of underground utility lines,
connections for gas, electric, and water/sewer lines, and installation of auxiliary buildings. The
total cost for these activities was calculated to be $3,700 for all cost cases. Construction of a
concrete pad for the major equipment and associated grading requirements were considered
technology-specific requirements and cost about $8,500. An additional concrete pad was built
due to an error in specifications, which contributed an additional cost of $8,000 (for a total of
$16,500) for the actual case that would not be incurred in the ideal or the typical cases.
Rental of the office trailer cost $342 per month, based on actual invoices. For the actual case
(25 months of operation), office rental costs totaled $8,930 including delivery charges. A roll-off
bin, borrowed at no cost from the Rainbow Disposal site, was used as an auxiliary storage and
maintenance trailer. Costs for the buildings for the ideal case also included rental for the office
trailer at a total cost of about $4,660 for 12 months of rental including delivery. A cost of about
$14,900 for rental of both an office and a storage/maintenance trailer was calculated for the
typical case based on a rental cost of $500 per month. Office and storage space requirements are
site-specific and depend on climate, geographical location, and available space and buildings on
the treatment site.
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3.4.2 Permitting and Regulatory Costs
Several types of permits are required for installing and operating the SERF technology. Costs
incurred include permit application fees and permit compliance fees. Costs were included for the
following permits: permit to construct (SCAQMD), permit to operate (SCAQMD); NPDES
permit for effluent discharge; well drilling permit (may not be required when less than 40 feet
deep and no aquifers penetrated); and air permits for process equipment and the TOU. The
NPDES permit was estimated to have cost $2,000 per year (for a total of $4,000 in the actual
case). The cost for the remaining permits were estimated at $6,000 over the course of the
project, for a total of $10,000. For the ideal case, a permitting cost of half the actual case was
assumed ($5,000), since most permits are issued on an annual basis.
Also included in this category are costs for development and initiation of an appropriate
environmental monitoring plan. These costs include engineering costs, reporting, and project
management time to discuss these issues with the regulators. The cost for initiating the
environmental monitoring program was estimated to be approximately $6,100. Regardless of
how long the cleanup takes, this cost is incurred at the start of a project; therefore, this amount
is the same for the actual and the ideal cases.
Permit costs are dependent on the local and regional conditions and environmental laws.
California has rigorous environmental policies, and permit costs for this state are expected to
be higher than the national average. Permit requirements and associated permitting costs can
change rapidly, even over the course of a two-year project. For the typical case, permitting
costs, including development of a monitoring program, were estimated to be about $14,100.
However, depending on site-specific conditions, contaminants, and other factors (geological,
ecological, and political), these costs could fluctuate significantly.
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3.4.3 Equipment Costs
Costs for major and some minor equipment were received from the technology operator and
based on actual invoice figures in 1991 dollars. The major equipment components are: two
boilers, the thermal oxidizing unit, the ion exchange water softening unit, and the effluent
treatment system (tanks and filters). The total cost for the major equipment was about $402,000.
This cost was used to calculate the depreciation cost for use of the technology for all three cost
cases (see Section 3.4.4). The items were sold at the end of remediation for $100,000 and were
removed from the site by the purchaser.
Minor equipment includes items such as the following: tanks, well water collection systems, heat
exchangers, an oil/water separator, well materials and headers, casings, well pumps, piping,
metal trench plates, and miscellaneous monitoring equipment. This equipment was assumed to
have been exempt from depreciation; the total cost for this equipment is included in the cost
totals. The total cost for minor equipment, calculated from information received from the
operator along with catalog pricing information [4,5], is about $519,000. Some of the minor
equipment and associated materials may have salvage value at the end of the project. Well
casings and in situ instrumentation were assumed to be non-reusable; however, they may have
scrap value. If the costs for removing the materials is higher than the potential scrap value, and
removal is not necessary for site restoration, these materials may be abandoned in place.
Rental equipment was used during the start-up phase of the project to assist in installation of
process equipment. A forklift was rented for ten days at a daily cost of $45. A crane (with
operator) was required to set up the boilers and other heavy equipment at a cost of $190/hour.
The crane was assumed to have been rented for two eight-hour days. A forklift was borrowed
from the site owners during treatment, so rental was not necessary. A pump was rented for
approximately 10 days (at $50/day) to help clear some wells after heavy rains, but pumps were
not assumed to be required for the ideal case or the typical case. For the typical cost case, where
a forklift might not be readily available, use of a forklift for a total of 35 days (one day every
two weeks) was added to the rental equipment costs.
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3.4.4 Start-up and Fixed Costs
Start-up costs include installation of the process equipment, equipment shakedown, initiation of
the monitoring program, working capital, depreciation, insurance, and contingency costs.
Installation of the equipment for this in situ process included well drilling and installation
($191,000) and installing the aboveground process equipment and piping ($58,000). Well drilling
costs were the same for all cases of this cost estimate and were based on available drilling rates
and known time to drill and construct wells.
Shakedown costs were incurred over the two-week period when the system was tested.
Treatment was initiated on a small area of the treatment zone to test the wells and all the
aboveground equipment. Shakedown costs include the labor and materials for the shakedown.
Eight-hour work days were assumed. The total costs for shakedown were the same for all cases
of this cost estimate and were estimated to be about $52,800.
In this cost estimate, working capital was assumed to be the cash required to run the process for
a period of one month. This figure included approximate costs for monthly utilities, supplies,
rentals, and monthly monitoring requirements. Because Hughes Environmental Systems had a
parent company responsible for direct payment of the employees involved during treatment at
the Rainbow Disposal site, this cost did not include labor. Working capital was calculated to be
$30,000.
Depreciation is the cost for use of all the major equipment over the course of the project. For
the actual case, this included two years (746 days) worth of equipment use and also accounted
for the resale value received for the equipment at the end of the project ($100,000). Therefore,
an equipment life of two years was used to calculate the depreciation costs for the actual case.
The ideal and the typical cases either assume that a selling cost close to the book value could
be achieved or that the teclmology operator had another use for the equipment after the
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remediation. Depreciation was calculated using a straight-line method with a ten-year equipment
service life and the number of years (or fractions of years) of remediation.
Costs for insurance and taxes were estimated as approximately 2.5 percent of the total cost of
the equipment per year. These factors were estimated to be approximately $50,000, $25,000,
and $33,300 for the actual case, the ideal case, and the typical case, respectively.
Initiation of the monitoring program was also included in the start-up cost category. These costs
typically include operator training required and collection of the first site or process samples
used to establish a baseline for operations. The total cost for initiation of the monitoring program
was estimated to be $5,000 for all cases.
Contingency represents the amount of money the operating company has available for unexpected
needs. This was estimated to be $10,000 for all cost cases.
3.4.5 Labor Costs
The labor costs for the actual case were based on hourly wage figures and weekly schedules
supplied by the technology operator. For approximately the first year of operation (61 weeks),
the process was operated for 16 hours per day, 5 days per week. Full-time workers during two-
shift-per-day operation included a site supervisor ($60/hour), site engineer ($75/hour), and two
technicians/boiler operators ($40/hour each). The project director charged an average of ten
hours each week to the project at $100/hour, and an administrative secretary ($40/hour) was
employed for approximately 30 hours each week. Additional labor in the form of off-site
company administration (ten hours per week at $50/hour) and additional maintenance personnel
(15 hours per week, $50/hour) were assumed to have been required. The total weekly cost for
two-shift-per-day operation was calculated to be $11,500.
When the 24-hours-per-day, six-day s-per-week cycle of operation was started, labor costs were
increased with the addition of another full-time technician. The secretarial position was split with
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another job, so only 25 hours per week were devoted to the SERF project. The total weekly
costs for the three-shift per day operation were about $14,500 for over 45 weeks.
The weekly cost for the three-shift-per-day operation was also used to calculate the cost for the
ideal case. The same weekly schedule was used for the typical case. Southern California labor
rates are approximately 127% of the national average, so weekly labor costs used for the typical
case have been adjusted. This figure was determined based on average regional labor cost data
[3]. In the Northeast, labor rates are similar to those in Southern California, while other areas
of the country have rates that average two-thirds of the Southern California rates.
In this cost estimate, the total labor costs calculated for the actual case were $1,362,000, of
which 75 percent was for technical and engineering functions. The total costs calculated for the
ideal and typical cases were approximately $775,600 and $1,033,600, respectively.
3.4.6 Consumables and Supplies Costs
The major consumables used during treatment with SERF were water softening salt and two
water treatment chemicals used to protect the boilers from scaling and fouling. The water
treatment chemicals were purchased from Blackhawk Engineering Company. Blackhawk 625
(BH625) is an oxygen scavenger used to control corrosion, while Blackhawk 689 (BH689) is a
polymeric dispersant used to control boiler scale. A total of 30 tons of salt were used during
treatment at a cost of $0.11 per pound. A total of 3,000 pounds of BH625 (at $2.05 per pound),
and 650 gallons of BH689 (at $12.50 per gallon) were used. The total cost for these consumables
was about $21,200.
For the ideal and typical cases, the amount of salt and chemicals used was calculated based on
the average daily use of these chemicals during 24-hour-per-day-operation (100 pounds salt, 5
pounds BH625, and 1.1 gallons BH689), and the total assumed number of days of treatment.
Costs for the ideal case were estimated to be approximately $13,200; costs for the typical case
were estimated to be approximately $17,600. Costs for water softening and treatment are
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influenced by the quality of the water available, but this factor was not considered in the
analysis.
Other supplies used during the project included filters and carbon for the water treatment system;
maintenance and cleaning materials such as oil, detergent, and fuses; monitoring supplies such
as strip chart paper and calibration gas; health and safety supplies such as disposable gloves; and
office supplies. The rate of use of these supplies was based on operator log entries for the actual
case and was assumed to be basically proportional to the number of days in operation for the
ideal and typical cases. One full set of carbon and filters was included with the treatment system
as installed. Supplies were calculated to cost a total of $22,230 for the actual case, $11,120 for
the ideal case, and $14,820 for the typical case. The total cost for consumables and supplies was
calculated for the actual, ideal, and typical cases to be approximately $43,430, $24,320 and
$32,420, respectively.
3.4.7 Utilities Costs
The major utility required for treating the Rainbow Disposal site with SERF was the natural gas
needed to fire the steam boilers. A total of approximately 800,000 therms (1 therm = 100,000
BTUs) of natural gas were used over the course of the project at a cost of $0.611/therm for the
summer months (April through November) and $0.754/therm for the winter months, for a total
cost of approximately $527,000. Based on this cost estimate, natural gas use alone was more
than 10 percent of the total cost for use of SERF.
For the ideal case, the following factors were used to calculate the natural gas used: the average
monthly natural gas usage during 24-hour operation (33,000 therms/month), twelve months of
operation, and an average natural gas cost/therm of $0.654. The total natural gas cost was
approximately $228,000.
For the typical cost case, the average monthly usage of 33,000 therms was used to determine
the monthly gas costs using the monthly charges and gas rates for the cities investigated. Because
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different utility companies charge for natural gas using different combinations of monthly and
usage charges, a monthly cost for gas was calculated for each locale and then the monthly costs
were averaged. The average monthly charge for the natural gas was calculated to be $15,800,
for a total of approximately $269,000. Natural gas rates vary by season and by region; the rates
investigated for this analysis ranged from $10,000 to $20,000 for a month. In some locations,
higher costs for natural gas and less stringent air quality regulations may make alternate fuels,
such as diesel or gasoline, more attractive although this has not been figured into the cost
calculations.
A large quantity of water, at least 12 million gallons, was used over the course of the project.
At the Rainbow Disposal site, water was supplied by an on-site deep water well, formerly used
by an ice company, and was available at no cost. Therefore, for the actual case, the cost for
water was $0. The cost of the water used for the ideal case was also assumed to be $0. Costs
for water discharged to the storm sewer were assessed only through the NPDES permit, with
no additional charges based on actual gallons discharged. The same is assumed for the ideal
case.
The totalizing meter used to record the amount of well water used in the process was calibrated
at the conclusion of treatment according to procedures specified in the QAPP. At that time, the
meter was found to be inaccurate at the typical flow rates used during treatment. Based on the
field calibration and further calibration and testing performed by the meter manufacturer at the
conclusion of the Demonstration, actual total flow was estimated to have been 110 to 130 percent
of total meter reading. Since no charges were incurred for using water at the Rainbow Disposal
site, this did not affect the costs for the actual or ideal cases. However, a correction factor of
1.2 was applied to the amount of water used presented here. This corrected value was used to
calculate the cost of water for the typical case. Costs for water represent a small portion, less
than one percent, of the total cost for use of SERF, so a small discrepancy in the actual amount
of water used is negligible in the total calculated costs at the level of precision of these cost
estimates.
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For the typical case, an average cost for high-grade industrial or potable water was used in the
calculation ($2/1,000 gallons), and water was assumed to be used at the same daily rate as the
average during 24-hours-per-day operation at the Rainbow Disposal site (24,000 gallons,
corrected). The total cost for process water for the typical case was calculated to be
approximately $21,400. Sewer charges for the typical case were assumed to be charged on a per-
gallon basis (at $0.10/gallon), based on the average daily water discharge for the actual
remediation (2,500 gallons), and the number of days assumed for the typical case. This cost was
estimated to be about $133,000. Sewer charges are expected to be highly site-specific.
Electricity service costs were based on an average monthly cost of $4,000 reported from
invoices. Electricity use stayed fairly constant over the course of the project. A total cost of
about $99,500 was calculated for the actual case, about $49,700 for the ideal case, and $66,300
for the typical case.
Phone service was calculated based on a monthly rate of $200, which included a three-line
business system and a reasonable number of toll calls. The total cost for phone service was
estimated to be about $4,970; $2,490; and $3,320 for the actual, ideal, and typical cases,
respectively.
3.4.8 Effluent Treatment and Disposal Costs
The liquid effluent from the SERF process is composed mostly of oily water removed from the
extraction wells. During the Demonstration, this water was treated in the aboveground system
and released to the storm sewer. Costs for the treatment equipment were included with the
equipment costs (Section 3.4.3), and the cost for filters and carbon was included with supplies
and consumables costs (Section 3.4.6). Calculated sewer discharge costs (for the typical case)
were included in the utilities category of this cost estimate (Section 3.4.7). Other costs for the
disposal of the treated water were incurred during monitoring and reporting for the NPDES
permit requirements. The monitoring included sample containers, analytical services, data
interpretation, and report generation for the regulatory authorities. Samples were collected
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weekly during treatment and analyzed for total petroleum hydrocarbons (TPH) and benzene,
toluene, ethylbenzene, and xylenes (BTEX). Calculated costs were based on collecting four
samples per month for two parameters each with an approximate analytical cost of $1,760 per
month, handling cost of $100 per month, and reporting cost of $1,000 per month. The total costs
for the actual case were calculated to be about $71,100. Costs for the ideal and typical cases
were based on the same frequency of monitoring over the shorter durations of treatment, and
total approximately $35,600 and $47,400, respectively.
In some cases, discharge to a storm sewer would not be appropriate due to waste constituents
or local water conditions. In these situations, wastewater would need to be handled in some other
manner, such as secondary on-site treatment, discharge to a POTW, or off-site hazardous waste
disposal. Costs for these other disposal options would probably be much higher than for NPDES
discharge to a storm sewer.
3.4.9 Residual and Waste Handling and Disposal Costs
Several types of wastes are generated during treatment with the SERF process. These include
drill cuttings from well installation and sampling boreholes, collected fuel product from the
oil/water separator, spent carbon from the wastewater treatment system, oily sludge (bottoms)
from the oil/water separator, and used disposable tools and protective clothing.
During the Demonstration, drill cuttings were placed into 55-gallon drums which were
segregated by borehole number and drilling depth. Drums were purchased for approximately $30
each. Drill cuttings, which were determined to be uncontaminated based on analytical results,
were redeposited on the site as fill at a negligible cost (about half of these drums could be
reused). Approximately 137 drums of drill cuttings (out of approximately 460 drums collected)
required off-site disposal at a certified landfill at a disposal cost per drum of $250. For this cost
estimate, the ideal and typical case costs for drill cutting disposal were calculated based on the
sum of the actual number of boreholes drilled before and after treatment and an estimated
number of boreholes that would be required during interim sampling. Since interim sampling
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was performed quarterly, the number of interim sampling events was estimated based on the
assumed treatment time for the ideal and typical cases. Two drums of drill cuttings were
normally generated per borehole drilled. It was assumed that a total of 108 (out of 360), and 115
(out of 385) drums required disposal for the ideal and typical cases, respectively.
During the Demonstration, the contaminated activated carbon from the water treatment system
was changed once during operation and once at the end of treatment. This generated 38 drums
of contaminated carbon for disposal at a cost of $450 per drum. The same cost was assumed for
the typical case. For the ideal case, only one change of carbon was assumed to be required,
resulting in approximately 19 drums of spent carbon requiring disposal. Approximately ten
drums of sludge from the oil/water separator were disposed of at a cost of $280 per drum; this
cost included drum purchase price and was used for all cases.
Less liquid diesel was recovered during treatment with SERF than originally anticipated because
most of the contamination was extracted in the vapor phase and could not be condensed to the
liquid phase by the process. A total of approximately 4,700 gallons was collected over the course
of the remediation, most of which was pumped from the extraction wells as free product on the
water table. Recovered diesel can be recycled or disposed of, with a cost involved for either
option. A cost of $l/gallon, or approximately $4,700, was calculated for disposal of the
recovered diesel based on quotes from fuel blending and disposal companies. This same disposal
cost was used for all three cases of this cost estimate.
Additional wastes requiring disposal included disposable equipment and other solid wastes. Since
contact with the diesel only occurred during sampling activities, most of the disposable clothing
and materials were disposed of with other solid wastes. Rainbow Disposal personnel collected
non-hazardous solid wastes from the site during their normal operations, and no costs were
incurred for this service. For the typical case, trash disposal might require a tipping fee which
was estimated to be $500 total for the project. Well casings and other materials removed during
demobilization also required cleaning, handling, and disposal, incurring an additional cost.
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3.4.10 Sampling and Analytical Costs
Sampling and analytical services were required for soil, groundwater, and process liquid streams
during the project. The cost for operational analysis for the wastewater treatment system was
previously included under effluent treatment and disposal. Soil sampling was conducted at the
beginning of the project, at quarterly intervals during treatment, and at the end of the project.
Groundwater was sampled monthly during treatment.
The cost for analytical services was based on the number of samples collected, the analyses
performed, and the reporting requirements for each analytical event. For pre-treatment sampling,
30 soil samples and 40 groundwater samples were collected and analyzed for BTEX, TPH, and
semivolatile organic compounds (not all samples were analyzed for all parameters). Eight
boreholes were directly attributed to pre-treatment sampling; other boreholes sampled were
included as a part of process well installation. The cost of pre-treatment sampling used in this
economic analysis was estimated to be approximately $31,800. This cost was used for the actual,
ideal, and typical case.
Interim sampling for the actual case was estimated to have cost approximately $209,000 over
the course of the project. This is based on the drilling of about 12 boreholes and collection of
30 groundwater and 30 soil samples per quarter for analysis for TPH and BTEX (actual
quarterly sampling schemes and numbers of samples varied for each instance). Costs for interim
sampling for the ideal and typical cases were based on the same sampling frequency over the
shorter duration of treatment. Costs for interim sampling for the ideal and typical cases were
estimated to be about $105,000 and $131,000, respectively.
Confirmation analyses for the Rainbow Disposal site, including drilling and sampling, were
performed by the SITE Program. The confirmation analyses cost presented for the actual case
was estimated based on the costs incurred by the SITE Program for these analyses, adjusted for
the smaller number of samples that probably would have been collected if the operator conducted
the confirmation sampling. Some sampling and analysis is required to determine whether the
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cleanup criteria have been met. The costs were based on drilling 20 boreholes and collecting and
analyzing 50 samples for BTEX and TPH and include sampling, handling, and reporting costs.
The total cost for confirmation sampling was estimated to be about $59,100 for all cost cases.
3.4.11 Maintenance, Repair, and Modification Costs
Maintenance and modification of the SERF system occurred almost continuously during
treatment. Normal maintenance costs were included under the labor costs category (Section
3.4.5) and the consumables and supplies costs category (Section 3.4.6). Labor for repairs and
modifications was also included in the labor rates described for labor costs. Maintenance and
modification costs included in this section include costs for outside contracting for repairs, repair
materials, and replacement parts. Specific design adjustments and modifications made during
treatment included adding and abandoning injection and extraction wells (five were added during
treatment); fabricating a condenser; hard piping the extraction wells after the hoses had started
to deteriorate; and modifying parts of the TOU to resist corrosion. Design adjustments were
estimated to have cost approximately $56,500 over the course of the project; the cost for
replacement and repair was approximately $94,200.
The rate of both repair and modifications were assumed to increase as the process operates,
since parts wear out. If the treatment at the Rainbow Disposal site had taken only the anticipated
eight months, items such as well headers and extraction hoses would not have required
replacement. Design adjustment and modification costs were assumed to be five percent of the
major equipment cost (per year and fractions) for both the ideal and typical cases, estimated as
approximately $20,600, and $27,400, respectively. Replacement costs were based on a
percentage of the total equipment costs. Four percent of the total equipment cost (per year and
fractions) was used to estimate the cost for replacement for the ideal and typical case, for costs
of approximately $36,900, and $50,200, respectively. These costs are estimates only and depend
on site and equipment-specific factors. Because the application of SERF at the Rainbow Disposal
site was the first full-scale application of the technology, lessons were learned about process
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equipment requirements which can be used to reduce modification and repair costs for
subsequent applications.
3.4.12 Demobilization Costs
Demobilization of in situ SERF is as site-specific as the installation and start-up. Depending on
the site, demobilization might include removal of the aboveground process equipment, removal
or abandonment of the process wells, site restoration, continued monitoring, or further
treatment. At the Rainbow Disposal site, the process equipment (major equipment and some
minor equipment) was purchased by an outside company for a total of $100,000. In return, the
purchaser removed the equipment from the site. This resale figure was used in the calculations
for depreciation over the life of the operation. It is likely that Rainbow Disposal realized some
salvage value on items of equipment that could not be sold, since recycling and reclamation is
part of its business. This savings is probably negligible, considering the extra labor that would
be involved in preparing the equipment for salvage, and has not been included in the cost
calculation.
The process wells were removed from the site according to Regional Water Quality Control
Board specifications and well holes were filled with new grouting. Piping was removed from the
trenches along with the gravel, and the trenches were filled with soil. The entire site was then
covered with concrete, including the formerly bare "dirt lot" area as a part of the Rainbow
Disposal operational expansion. The total cost for technology-specific removal and site
restoration was estimated, based on information supplied by the operator, to be $92,000 for the
actual case. This cost was also used for the ideal and typical cases because these costs are so
site-specific. Since the Rainbow Disposal site is in an area zoned for industrial use and will
remain covered by a concrete cap and in operation for at least the next seven years (the interval
of the current disposal contract), little other site restoration was required. Costs at a site that
requires restoration to a near-native state could be much higher due to additional costs for
removal of concrete or asphalt capping, site grading and capping, and other requirements.
62
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Other demobilization costs incurred at the Rainbow Disposal site included severance pay for laid-
off workers ($43,700), excess inventory that had not been used by the end of the treatment
($1,000), return of rental offices and other equipment ($1,000), and miscellaneous expenses
($1,500). These are much higher in the actual case than would be expected for any subsequent
application due to the sudden decision to stop work on the site. Severance pay was not included
in the ideal or typical cost case estimates.
Because the SERF technology did not meet the regulatory cleanup criterion, Rainbow Disposal
proposed performing groundwater monitoring on a frequent and regular basis to confirm that the
potential for off-site migration of the contamination has been mitigated. Since the site will
remain in operation and covered by concrete, there is no hazard to workers or the public from
any contact with contaminated soils The costs for long-term monitoring are the responsibility
of the site owner and were not included in the cost estimates presented here.
The total estimated cost for demobilization at the Rainbow Disposal site was estimated to be
about $139,200. Costs for the ideal and the typical case costs were estimated to be about
$98,500 for both cases.
63
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SECTION 4
TREATMENT EFFECTIVENESS
4.1 BACKGROUND
4.1.1 Site and Contamination
The Rainbow Disposal site is an active municipal trash transfer facility. Six days per week,
trucks collect and deliver municipal trash to this site, where the trash is sorted and placed into
other trucks for recycling or disposal. Rainbow Disposal currently is the sole company
responsible for waste pickup from five cities in the Orange County, California area.
The site became contaminated in 1984 when an underground diesel fuel pipeline, used to supply
fuel to the trucks, was punctured during digging operations. The leaking pipeline was not
discovered for approximately 22 months, during which time a large quantity of diesel had leaked
into the surrounding soil. Preliminary investigations showed that the soil under the Rainbow
Disposal site had several distinct layers composed of alternating bands of permeable sand and
low permeability clay. The layers influenced how the fuel became distributed in the soil. The
fuel flowed downward under gravity through each sand layer. At each sand/clay interface, the
fuel was forced to flow horizontally until breaks in the underlying clay allowed further
downward flow. A perched aquifer located in a sand layer between 25 and 40 feet below the soil
surface (known as the B-sand) prevented the fuel from flowing further downward while allowing
for wide lateral spread. The contamination distribution that resulted included elevated levels of
fuel compounds at all depths at the point of the spill and a zone of contamination, which extends
for more than two acres laterally, in the sand layer between approximately 25 and 35 feet.
Beneath the B-sand layer was a thick clay layer that protected a confined aquifer beneath from
contamination. A perimeter designating where soil concentrations were above 1,000 mg/kg of
total petroleum hydrocarbons (TPH) was drawn after further site investigation, as shown in
Figure 4-1. This perimeter was used as the treatment area for SERF.
64
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* *
S-15
t-
i—m
' '1
0 30 60 90
Feet
D /
•S-16 X
°,o
«S-2
0
Ek •S-IS
*S"6
0
D
D
• S-7 S-21
0
«S-8
D
• o
S-10
D
D
SERVICE SHOP
•S-9B
OFFICE
• S-ll
n n
/
rtZ)
y
a
^
0 0
TRANSFER BUILDING
O INJECTION WELL
O EXTRACTION WELL
• SAMPLING LOCATION
PERIMETER OF
CONTAMINATION
D
C
Figure 4-1. Pre- and Post-Treatment Sampling Locations at the Rainbow Disposal Site
It was originally estimated that between 70,000 and 135,000 gallons of No. 2 diesel were
released into the site [7,8]. Free product was present in most monitoring wells screened above
40 feet in the zone of contamination. Approximately 4,000 gallons of free product were pumped
from these wells, along with the ground water from the perched aquifer, during well installation
[7,8]. The perched aquifer remained drawn down throughout treatment with SERF.
Because the services provided by Rainbow Disposal were indispensable in the community, and
operations could not be resumed at a different location, Rainbow Disposal required a remedial
technique that could clean up the site without completely disrupting the ongoing operations. In
situ SERF was selected because of the developer's claims that major excavation of soil would
not be required and that the technology could be installed and operated below the soil surface.
65
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The SITE Program became involved with the Rainbow Disposal site after most of the
preliminary investigation had occurred and the remedy had been selected for the cleanup. The
SITE Program was involved with an evaluation of steam injection technology at another site, and
saw the concurrent evaluation of the full-scale SERP technology during the Rainbow Disposal
site remediation as an excellent opportunity to gain additional knowledge of steam injection
technology.
4.1.2 Treatment Objectives
The objectives for the cleanup at the Rainbow Disposal site were driven by the requirements of
the lead regulatory agency, the Regional Water Quality Control Board (RWQCB). The soil
cleanup level for the site was determined based on risk assessment, and was set at 1,000 mg/kg
(ppm) of TPH as determined by the diesel fraction analysis of the California LUFT method.
Additionally, the RWQCB required that the technology should not cause further spread of the
diesel fuel into otherwise unimpacted areas adjacent to or below the contaminated strata.
There were two critical objectives for the SITE Program Demonstration of the SERP technology:
(1) to evaluate the ability of the technology to meet the cleanup requirement set by the RWQCB
for the site soil, based on soil sampling results; and (2) to perform a detailed economic analysis
of this full-scale application of the technology.
Comparison of pre- and post-treatment soil data was performed only for informational purposes.
The determination of contaminant removal efficiencies could not be designated as a critical
objective because the SITE Program was not involved with the Rainbow Disposal site
remediation at the beginning. Pre-treatment sampling was conducted at the site by the developer
prior to the completion of a SITE Program Quality Assurance Project Plan (QAPP) for the
Demonstration.
66
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4.1.3 Treatment Approach
The technology was configured to treat the entire contaminated area (2.3 acres to a depth of
approximately 40 feet) simultaneously. Since it was known that some portions of the site were
much more contaminated than others, the technology could be and was adapted during treatment
to try to focus the action of the steam and vacuum on portions of the site which required
additional treatment, while shutting down the process in portions of the site presumed to be
clean. Quarterly soil sampling and analysis was conducted by the operator and helped to guide
the operation.
4.2 TESTING METHODOLOGY
The pre-treatment soil sampling borehole locations were selected and sampled by the technology
developer with input from the SITE Program. Twelve boreholes were drilled within the
treatment area. These are marked on Figure 4-1 as boreholes 1 through 12. Several sample
borehole locations were selected in the area of the spill zone. Other borehole locations were
selected based on the known distribution of site contamination and the configuration of the
technology such as in areas that might be expected to have greater or lesser cleanup efficiency
based on the anticipated steam flow pattern. Vertical sampling locations within each borehole
were selected during sampling based on lithology and readings from a hand-held organic vapor
analyzer; one to four samples were collected from each borehole for laboratory analysis.
Samples were collected at discrete depths up to 40 feet below ground surface. One of the
designated pre-treatment sample borehole locations was not sampled due to underground
obstructions.
A total of 24 soil samples were collected during pre-treatment sampling. The soil samples for
laboratory analysis were collected in brass tubes six inches in length and two inches in diameter.
Pre-treatment soil samples were analyzed for total petroleum hydrocarbons (TPH—diesel
fraction) and BTEX. A small number of samples were also analyzed for semivolatile organic
67
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compounds (SVOCs) to check for the presence of polynuclear aromatic compounds typically
found in diesel.
The sampling and analysis plan for post-treatment soil sampling was designed based on pre-
treatment soil sampling data and other site characterization information. The number of borehole
locations and samples were determined based on a geostatistical analysis of pre-treatment data.
Geostatistical methods were also used to evaluate post-treatment soil sample data. A total of 72
samples from 24 boreholes were collected after treatment. Twelve of these boreholes were
located adjacent to the 12 pre-treatment borehole locations, including the borehole location that
was not sampled. These paired boreholes were within three to four feet of each other. Samples
from the paired post-treatment boreholes were collected from the same depths as those for pre-
treatment, and also from additional depths. Within the perimeter of contamination, primary
samples were collected at two to four discrete depths up to 40 feet below ground surface.
Seven of the post-treatment boreholes (numbered 12 through 18 on Figure 4-1) were located
outside of the established perimeter of contamination in areas that were known to be clean or
had levels of contamination less than 200 mg/kg of TPH. Two samples with depths between 25
and 40 feet were collected from each of these boreholes in order to detect any lateral off-site
migration of contaminants during treatment.
The remaining five post-treatment borehole locations were in areas of the site that were
determined to be under-represented in the pre-treatment sampling. The locations of the post-
treatment boreholes in relation to landmarks on the site and the contamination perimeter are
shown in Figure 4-1. On the scale of this drawing, the pre-treatment boreholes correspond
directly to those for post-treatment with the same numbers.
Because in-place soil contamination can be highly variable, triplicate sampling was performed
to assess the contaminant variability over short distances. To accomplish this, duplicate and
triplicate samples were collected at six primary sample locations. The specific locations for
triplicate sampling were selected randomly prior to treatment. The triplicate samples were
68
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collected vertically within an 18-inch split spoon sampler in separate brass sleeves. Six three-
inch-long sleeves were used in the split spoon to collect the soil. The first, third, and fifth
sleeves were used for TPH and TRPH analysis, while the remaining sleeves were used for
BTEX analysis. Each sample was analyzed separately to allow the variability inherent in the soil
matrix to be statistically determined.
Samples collected after treatment were analyzed for TPH, total recoverable petroleum
hydrocarbons (TRPH), and BTEX. The analysis of TRPH was conducted in addition to TPH
because TRPH is an approved EPA method, while TPH, though widely used, is a California
state method and is not an approved EPA method. The TPH method (modified SW-846 Method
8015) analyzed extractable petroleum hydrocarbons by Gas Chromatograph/Flame lonization
Detector. Methylene chloride is used in this method to extract the sample. The TRPH method
(EPA Method 418.1) used an infrared instrument to analyze petroleum hydrocarbons.
Fluorocarbon-113 is used in this method to extract the sample. The analysis of BTEX was
required by the RWQCB even though BTEX compounds were only present in a few of the pre-
treatment soil samples.
SVOCs were not positively identified in the pre-treatment samples due to their low levels in the
soil and to matrix interferences from the high levels of TPH. Therefore, analysis for SVOCs was
not performed for post-treatment samples, and no conclusions can be drawn about their removal
by the technology.
Quality assurance and quality control samples, including equipment blanks and trip blanks were
also collected and analyzed during the post-treatment sampling event to ensure that the data was
of good and known quality. Matrix spike and matrix spike duplicate samples were analyzed for
all three analytical parameters. Quality control standards were also analyzed.
Groundwater conditions were beyond the scope of the SITE Program SERP technology
evaluation, and groundwater samples were not collected for this purpose. Due to regulatory
requirements, the technology operator performed routine monitoring of the confined groundwater
69
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aquifer. According to the operator, this routine monitoring detected no degradation of
groundwater quality during use of the SERF technology.
4.3 PERFORMANCE DATA
4.3.1 Soil Sample Analyses
Table 4-1 presents the post-treatment soil sampling results for TPH and TRPH. Based on
analysis of the post-treatment TPH and TRPH data, removal of contamination by the SERP
technology was less complete than expected. Forty-five percent of the post-treatment soil sample
results inside the treatment area were above the cleanup criterion of 1,000 mg/kg TPH. Seven
percent of soil samples had TPH concentrations in excess of 10,000 mg/kg.
No BTEX was detected in any of the post-treatment samples. The analytical detection limit was
6 /xg/kg. This may be an indication that the SERP technology was effective in removing these
compounds because BTEX compounds were found at low mg/kg levels in a few pre-treatment
soil samples. However, this finding is not conclusive. There were no cleanup criteria established
for BTEX compounds in soil.
Results of the analysis of triplicate samples were highly variable, showing that the site
contamination was heterogeneous even over small vertical distances (approximately three inches).
Table 4-2 presents the triplicate sample results and associated statistics.
A geostatistical analysis of the post-treatment soil data was conducted using a "nearest neighbor"
approach on a computerized model to assess the spatial variability of soil contamination and to
determine a weighted average of the soil results. The use of this geostatistical approach results
in the calculation of a more "unbiased" estimate of the true average level of contamination for
the site as a whole. This is particularly true when there is no pattern of spatial correlation such
as low spatial variability at short distances and high spatial variability at longer distances for soil
contamination, as was determined to be the case at the Rainbow Disposal site [9]. Based on the
70
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Table 4-1. TPH AND TRPH RESULTS FOR POST-TREATMENT SOIL
Boring
1
1
1
1
1A
1A
1A
1A
2
2
3
3
4
4
5
5
5
6
6
7
7
8
8
9B
9B
9B
10
10
10
11
11
Depth (ft)
16.5
26.5
30
35
15
25
30
35
32
35
32
38
30
38
30
35
38
32
40
25
35
31
43
25
32
37
30
37
40
30
35
TPH (mg/kg)
21
31,800
5,640
3,500
4.3
344
6,090
2,270
670"
960
392
4.2
6,800"
1,800
11
5,160
7,910
1,080
1,700*
3.3
9,330
3,360
15
2.6
3.4
8.5
69"
1,360
3,260
1,880
807
TRPH
(mg/kg)
60
12,500
1,430
1,100
<24
108
5,570
4,570
187"
376
190
<27
2,000"
604
<26
113
8,110
542
1,400"
<22
12,900
2,000
164
43
<20
<20
<55"
762
592
348
141
Boring
19
19
19
20
20
20
21
21
21
22
22
22
23
23
23
Depth (ft)
28
32
38
30
34
41
30
35
40
31
37
42
20
30
38
TPH (mg/kg)
41
351
232
1,880
21,600
2.8
10,900
9,080
1,020
14
177
628
5.5
6,100"
438
TRPH
(mg/kg)
214
686
232
1,610
1,690
307
25,400
9,740
952
151
96
291
<20
6,100"
770
Outside Treatment Area
12
12
13
13
14
14
15
15
16
16
17
17
18
18
33
39
32
38
30
40
31
36
35
39
31
36
30
35
3.6
4.2
7.8"
4.8
4.2
4.4
35
369
6.3*
4.3
3.2
3.3
4.1
6.2
<20
82
<40*
<20
<20
<20
<20
228
<42"
<20
<20
<20
<20
74
Average of Triplicate Results
< Not detected at detection limit shown
71
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Table 4-2. RESULTS OF TRIPLICATE ANALYSES FOR TPH AND TRPH
Borehole
Number
2
4
6
10
13
16
23
Depth (ft)
and
designation
32 primary
duplicate
triplicate
30 primary
duplicate
triplicate
40 primary
duplicate
triplicate
30 primary
duplicate
triplicate
32 primary
duplicate
triplicate
35 primary
duplicate
triplicate
30 primary
duplicate
triplicate
TPH Results
(mg/kg)
674
120
312
12,400
239
7,710
590
3,680
863
82
5.6
118
3.3
14
5.9
5.3
9.2
4.5
5,090
5,320
8,010
TRPH Results
(mg/kg)
80
161
321
1,450
259
5,820
1,150
2,460
638
<20
<20
127
<20
81
20
<20
85
<20
5,830
6,230
6,230
Standard
Deviation of
TPH Results
(mg/kg)
230
5,000
1,400
47
4.6
2.1
1,300
Standard
Deviation of
TRPH Results
(mg/kg)
100
2,400
770
>50*
>29*
>30'
190
< Not detected at the detection limit shown
* Calculated using non-detect results at the detection limit. Actual standard deviations may be slightly
higher.
72
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geostatistical analysis, the post-treatment weighted average soil TPH concentration is 2,290
mg/kg, with a standard error of 784 mg/kg. Based on an approximate normal distribution for
the weighted average, the 90 percent confidence interval for TPH concentration is 996 mg/kg
to 3,570 mg/kg. This large interval is because of the variability of site soil sampling results due
to the heterogeneity of the in situ soil; analytical variability was within established quality
control limits and contributed little to overall data variability. According to this analysis, at 90
percent confidence, the true average may be below the cleanup criterion of 1,000 mg/kg, but
this represents a small probability. Therefore, with almost 90 percent confidence, the average
concentration of the site soil after treatment with SERP is above the cleanup criterion.
The geostatistical analysis results for TRPH yielded a weighted average concentration of 1,680
mg/kg, with a standard error of 608 mg/kg. The 90 percent confidence interval for the weighted
average for TRPH is 676 mg/kg to 2,680 mg/kg. The calculated weighted average and
confidence interval for TRPH are lower in magnitude than for TPH. No TRPH cleanup criteria
were set for the Rainbow Disposal site.
Samples collected from areas outside the perimeter of contamination (those numbered 12 through
18) were analyzed for TPH, TRPH, and BTEX. Only one of the 12 samples collected had TPH
levels higher than 200 mg/kg, the limit used to determine whether lateral migration of
contamination due to treatment with SERP had occurred. Since this one sample was less than
twice the limit, and the variability found in samples from the site was so great, this result is not
felt to indicate that any significant lateral migration had occurred. Additionally, of the remaining
perimeter samples, only two contained greater than 10 mg/kg TPH and many contained levels
less than 5 mg/kg, which was the achieved detection limit during the original site survey. TRPH
results for samples collected outside the perimeter of contamination were similar to TPH results.
BTEX compounds were not detected above the 6 /zg/kg detection limit.
73
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4.3.2 Comparison of Pre- and Post-Treatment Conditions
A secondary (non-critical) objective of the Demonstration was to determine a removal efficiency
(or percent removal) by comparing pre- and post-treatment sample analysis data. Percent
removal was calculated for TPH only, since no pre-treatment TRPH data exists, and only three
of the pre-treatment samples contained detectable amounts of BTEX. Percent removals calculated
for each set of paired boreholes are shown in Table 4-3. Percent removal was calculated as:
Pre-treatment Concentration - Post-treatment Concentration ,„„
— — x 100
Pre -Treatment Concentration
Direct comparison of the paired borehole sample TPH results shows great variability for the data
set. This pairing analysis is of limited value because of the high spatial variability associated
with the in situ soil contamination. Samples from paired boreholes were located within three to
four feet of each other laterally and at the same depth; however, triplicate sample results over
much shorter distances (18-inches) showed variability as high as those between the pre- and post-
treatment paired boreholes. Some areas seem to show good or moderate reduction in
contamination, while other areas show increases in contamination, some of them rather large.
These results are supported by Figure 4-2 which presents the pre- and post-treatment data sets
in a histogram showing the percent of samples in incremental concentration ranges.
Due to the high spatial variability of the in situ soil contamination at this site, a more valid
approach to determine a removal efficiency is to pool pre- and post-treatment data sets for
comparison. To accomplish this, weighted average concentrations of TPH in the soil before and
after treatment were compared. A weighted average TPH concentration in the soil before
treatment was calculated using geostatistical modeling (nearest neighbor approach) as was done
for the post-treatment data. The weighted average pre-treatment concentration was calculated to
be 3,790 mg/kg with a standard error of 2,340 mg/kg. Since the distribution of the pre-treatment
weighted average did not conform to a normal distribution, the confidence interval on this
74
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Table 4-3. PERCENT REMOVAL FROM BOREHOLE PAIRS
Borehole
1
1
1
2
3
4
5
5
5
6
7
7
8
10
10
10
11
11
1A
1A
1A
1A
AVERAGES
Depth (ft)
15
25
30
35
32
30
30
35
38
32
25
35
43
30
37
40
30
35
15
25
30
35
Pre-Treatment TPH
Concentration (mg/kg)
3,480
11,300
4,870
1.3
728
3,860
2,240
325
312
2,800
10.6
39,100
469
472
3.2
72
165
810
1.2
4,180
4,160
1,380
3,670
Post-Treatment TPH
Concentration (mg/kg)
20.5*
31,800b
5,640
3,500
392
6,800C
11.4
5,160
7,910
1,080
8.3
9,330
12.3
69C
1,360
3,260
1,880
807
4.3
344
6,090
2,270
3,190d
Percent Removal
(%)
99
0
0
0
46
0
99
0
0
61
22
76
97
85
0
0
0
0
0
92
0
0
13
a Post-treatment sample was collected at 16.5 feet
b Post-treatment sample was collected at 26.5 feet
c Average of triplicate sample results
d Average for post-treatment was calculated using all the post-treatment data in the treatment
area, including data from boreholes which were not sampled before treatment.
75
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Percent of Results
40%
30%
20%
10%
0%
<5 10-50 100-500 1,000-5,000 > 10,000
5-10 50-100 500-1,000 5,000-10,000
Concentration Ranges (ppm)
Pre-treatment
Post-treatment
Figure 4-2. Histogram of Pre- and Post-Treatment TPH Concentration Data
average was calculated using a computerized "resampling" technique. This technique is often
used to more accurately estimate confidence intervals for statistics with non-standard and non-
normal distributions [10]. At 90 percent confidence, the calculated interval on this weighted
average is 1,390 mg/kg to 7,290 mg/kg. This large range is due to the smaller number of pre-
treatment samples collected and to the variability in the data set.
Comparing the pre-treatment soil TPH weighted average to the post-treatment soil TPH weighted
average, the overall removal efficiency was calculated to be about 40 percent. Using the
resampling technique to calculate the confidence interval, at 90 percent confidence, the percent
removal could be significantly higher or lower. This large uncertainty about the exact removal
efficiency is due primarily to the lack of sufficient pre-treatment sample measurements, and the
resultant data set variability. (Pre-treatment data were collected by the developer before the
preparation of the SITE Program QAPP.) According to process data, however, it is known that
some diesel contamination was removed from the soil during treatment.
76
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The amount of diesel recovered in the storage tank during treatment was measured and totaled
approximately 700 gallons at the end of the project. This is much less than the amount
anticipated to be collected when the system was designed and installed. Partly, this was due to
the poor effectiveness of the process at treating the site soil. However, this was also due to
design factors of the technology application including inadequate vapor stream condenser design.
More diesel was removed through the vapor treatment system and oxidized in the TOU than was
collected in the storage tank. Vapor concentration measurements taken at the inlet of the TOU
over the course of treatment by the flame ionization detector (and the LEL meter before the FID
was on line), along with the flow rate and inlet temperature, were used to estimate the amount
of diesel which was removed in vapor form.
Based on these data, it was calculated that approximately 15,400 gallons of diesel were treated
by the TOU. Therefore, a combined total of approximately 16,000 gallons of diesel were
removed during treatment with SERF. This volume, compared with the initial estimate of the
amount of fuel released (70,000 to 135,000 gallons [7,8]), less 4,000 gallons recovered prior
to treatment with SERF, suggests that between 12 and 24 percent of the original spill volume
was removed from the soil and treated above ground. This removal efficiency, based on diesel
recovered and treated, although lower than the removal efficiency based on the soil data, is
within the percent removal confidence interval for the soil data. It should be noted that vapor
stream system measurements were not critical measurements for this Demonstration.
4.3.3 Soil Temperature Data
Twenty temperature monitoring wells in and around the treatment area were used to measure the
soil temperature, determine the progress of the steam through the soil within the treatment area,
and ensure that the steam flow stayed within the treatment area. The locations of all these wells
are shown in Figure 4-3. Plots of the temperatures over time in selected wells are presented with
a discussion of what these temperature plots may indicate about the operation of the process in
different locations of the site.
77
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A
12
D /
/
a
, <
Fee. i 1 ' i
IN * ,7 A, , ,2A
U AA ° \ °
~ a 2 6, ^ o a a""-^- — a a
• 13 o x/ o o 28Q ^ Q ^3
*° X<-X ° ,- °. ,D „ D "a D ^,
0 / 23AGT-1OAI6*
0 / 0 ° A c^ J ~> ~1 A 0 0
S T^7^\ — 1 A |Tj|Tjl' 33
' a a a 22 isa a
o A o o o o
29 o .
AGT-4 A
° a a a a
0 o A o o o
.2* * *
°AGT-3 <
D D
SERVICE SHOP '
o o(
°/
— *
>
*
O INJECTION WELL
D EXTRACTION WELL
A TEMPERATURE
MONITORING WELL
PERIMETER OF
CONTAMINATION
T STORAGE TANKS
r**-~
1 \
\
OFFICE
— *— •
•^>
— i
a
D
a.
D
TRANSFER BUILDING
7=3 -^
a u
7A
A6
Figure 4-3. Temperature Monitoring Well Locations
A5
Figure 4-4 is a plot of the temperature versus time at Well 15. This figure shows little heating
of this area of the site at all depths. Since this well was close to underground tanks on the site,
the injection and extraction wells in this area were not turned on until late in the remediation,
at which time the area began to heat. Only the 30-foot depth appears to have reached the steam
temperature, and only for a period of a few weeks. However, temperatures recorded at 20- and
40-foot depths were increasing during this time.
Figure 4-5 is a plot of the temperature versus time at Well 23, and Figure 4-6 is a plot of the
temperature versus time at Well 24. As can be seen on the site map (Figure 4-3), Wells 23 and
24 are in a line between an injection well and an extraction well, with Well 23 being closer to
the injection well. As would be expected from the process, the two figures seem to indicate a
steam or heat front moving from the injection well towards the extraction well, since Well 23
heated up sooner than Well 24. No heating was seen at Well 23 until April 1992, which was
-------
200 -
08-01-91 10-21-91 01-13-92 04-06-92 06-29-92 09-21-92 12-14-92 03-08-93 05-31-93
Date
10' 20' 30' 40'
Figure 4-4. Soil Temperature Plot for Well Location 15
3-01-91 10-21-91 01-13-92 04-06-92 06-29-92 09-21-92 12-14-92 03-08-93 05-31-93
Date
10' 20' 30' 40'
Figure 4-5. Soil Temperature Plot for Well Location 23
79
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08-01-91 10-21-91 01-13-92 04-06-92 06-29-92 09-21-92 12-14-92 03-08-93 05-31-93
Date
10'
20'
301
40'
Figure 4-6. Soil Temperature Plot for Well Location 24
after the boilers had been recommissioned after lengthy downtime; Well 24 began heating in
June 1992. In both these wells, as in many of the other monitoring wells, the 30-foot depth
heated more effectively than the 20-foot depth or other depths. This indicates that the expected
steam flow pattern was established, from the injection interval (30 to 40 feet) to the higher
extraction interval (10 to 35 feet). Slower and more gradual heating at the 40-foot depth may
be due to the upward flow pattern developed, the influence of the cooler soil below, or to the
change in soil type near the bottom of the treatment zone.
Figure 4-7 shows the temperature profile for Well 27. Temperature probes were placed at
different depths in this well than in many of the other wells, showing more detail in the middle
depths. This graph shows a similar pattern of heating to that of Well 23, indicating that many
parts of the site started heating to steam temperature at the same time (April 1992). The steam
front reached this location at the same time for depths between 15 and 27 feet and slightly later
80
-------
200 -
5-01-91 10-21-91 01-13-92 04-06-92 06-29-92 09-21-92 12-14-92 03-08-93 05-31-93
Date
15'
32'
40'
Figure 4-7. Soil Temperature Plot for Well Location 27
for the 32-foot depth. The shallower depth of the initial steam front shown in this well could
have been caused by many factors, including soil types. Another reason for a different flow path
at this location is that this temperature well is located between pairs of the same type of process
well, rather than between an injection/extraction well pair as was the case for Wells 23 and 24.
Figure 4-8 is a temperature plot of Well 30, which is located further away from the spill zone
than the wells discussed previously. This plot shows a slightly different pattern of heating. In
October 1991, this location had nearly reached the steam temperature for all but the 10-foot
depth. Then the soil began to cool off, coinciding with the extended boiler problems experienced
in the winter of 1991/1992. Reheating in this location began in April 1992. However, the second
time the soil was heated, the temperature increased less rapidly. It is possible that the initial
steam front changed the soil (e.g., porosity or moisture content) which then retarded reheating
of the soil. If this is true of treatment with SERF, then intermittent operation could be very
81
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200 —
08-01-91 10-21-91 01-13-92 04-06-92 06-29-92 09-21-92 12-14-92 03-08-93 05-31-93
Date
10'
20'
30'
40'
Figure 4-8. Soil Temperature Plot for Well Location 30
inefficient, and reduction of downtime critical to effective operation. However, this area of the
site did stay heated after the steam temperature was reached again.
Figure 4-9 is a plot of the temperature at Well 33, which is near Well 15 and the location of the
initial diesel spill. The heating in this area was slow initially, and then intermittent for the rest
of treatment. A significant increase in temperature in this location was not seen until late June
1992. Well 33 is near two extraction wells, and began heating about the same time as well 24
which was also near an extraction well. This again seems to demonstrate the movement of a
steam front from injection to extraction well areas. The temperature fluctuated in Well 33 until
the fall of 1992 when it reached the steam temperature. The fluctuating temperature pattern may
have occurred because a nearby injection well was turned off for much of the treatment time to
protect the underground tanks. Also, since this temperature well is near two extraction wells,
the operation of the vacuum may have caused the soil to cool. The poor heating of this area,
82
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200 -
08-01-91 10-21-91 01-13-92 0406-92 06-29-92 09-21-92 12-14-92 03-08-93 05-31-93
Date
10'
20' 30'
40'
Figure 4-9. Soil Temperature Plot for Well Location 33
especially at the lower and higher depths (10 feet and 40 feet) may have led to poor treatment;
two nearby sample locations (S-1A and S-23) showed high levels of contamination after
treatment. However, the variability in soil concentration data limits this conclusion.
The last temperature graph shown here, Figure 4-10, is the temperature profile for Well 20. This
plot is also representative of Wells 17, 18, 19, 25 and 26 since they are located close together.
These wells were installed in a test plot used during shakedown testing of the process and
equipment. The wells in this location reached high temperatures sooner than other wells because
this area was treated much earlier and more intensely than the rest of the treatment area. The
temperatures recorded at Well 20, especially at the 20- and 30-foot depths, approximately
parallel to the operation of the process. Major downtime, which occurred over the winter of
1991/1992 and in the fall of 1992, is seen on the plot where the soil starts to cool. Injection
wells near this location were shut off in early 1993 to focus the operation elsewhere, which can
also be seen in the cooling of the soil near the end of treatment.
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200 -
08-01-91 10-21-91 01-13-92 04-06-92 06-29-92 09-21-92 12-14-92 03-08-93 05-31-93
Date
10'
20'
301
40'
Figure 4-10. Soil Temperature Plot for Well Location 20
From the examination of the soil temperature profiles, several general conclusions can be drawn
about the operation of SERF at the Rainbow Disposal site. Heating of the soil took much longer
than originally anticipated, and high soil temperatures needed to effect contaminant removal were
not maintained in many areas. This may have been due to the way the process was operated
initially and to excessive operational downtime. The steam flow patterns expected to occur in
the soil did seem to occur, including the development of a steam front which moved from
injection wells to extraction wells and from the injection depth upward towards the extraction
depth. Inspection of the temperature data collected also suggests that additional temperature
monitoring wells over the entire treatment area would have been useful in monitoring and
operating the process, which could have improved the remediation overall.
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4.3.4 Additional Process Data
Figure 4-11 is a graph of the monthly water use, based on flow totalizer readings, and monthly
diesel extracted from the soil in the vapor phase, calculated from FID and LEL readings of the
inlet vapor to the TOU. FID readings are only available from June 1992; LEL readings were
used for months before that. These two process measurements help to describe the operation of
the process. For example, the water used in a month indicates the amount of time the boilers
were operating that month and is therefore representative of the energy input to the soil in the
form of steam. Major equipment downtime occurred in the winter of 1991/1992, and in the
spring of 1993, which is shown by decreases in water use in this graph.
The calculated volumes of diesel recovered show the removal of hydrocarbons from the soil by
the technology, since most of the contaminant removed remained in the vapor phase. The
volume of diesel removed per month was dependent on several process factors including the
temperature of the treated soil, the amount of vacuum drawn on the soil, the number of
extraction wells in operation, and the number of hours in operation. It can be seen from the
Gallons
1,500
1,000
500
11!
1
I Well Water
, ,,f (gal/1000)
I Diesel Recovered
(gal)
II
1991 July Sept Nov 1992 Jan Mar May July Sept Nov 1993 Jan Mar May July
Date
Figure 4-11. Well Water Usage and Diesel Recovered at the Rainbow Disposal Site
85
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graph that a rapid increase in the diesel recovery occurred in April of 1992. Temperature
monitoring well graphs showed that the site was near or at steam temperature at this time after
the lengthy process downtime. Diesel recovery is lower after May of 1992, probably due in part
to intermittent TOU problems. Another reason for the decrease in removal may be because an
initial front of easily mobilized contaminant had been removed in April and May, leaving more
tightly bound contamination in the soil.
In October and November 1992, shortly after process operation was changed to a 24-hour per
day cycle, another peak hydrocarbon removal was reached. The removal remained high for
several months. When the removal dropped off, the operator felt this indicated that parts of the
site were becoming clean, and therefore started to turn off some of the injection wells in order
to concentrate the treatment on areas known to be more contaminated.
Each time a group of wells were shut off, this resulted in a small increase (peak) in removals
due to the effect of concentrating the steam and vacuum on a smaller, more contaminated area.
These smaller peaks, which cannot be distinguished on the monthly diesel recovery graph, taper
off more quickly than the original peak in October.
4.3.5 Reliability
The SERF system experienced many operational problems during the two-year treatment period.
The actual on-line efficiency during this period was determined to be about 50 percent based on
operational logs. Both of the boilers had operational downtime, frequently simultaneously, which
delayed the heating of the soil. The boiler downtime was due to structural, mechanical, and
electrical problems, and in approximately a half-dozen instances resulted in downtime of several
weeks or more during repairs. Intermittent operation of the boilers probably contributed to these
problems. The change from 16-hour- to 24-hour-per-day operation lessened the thermal shock
on the boilers from frequent starting and stopping and helped to prevent further problems. Some
boiler problems could be traced to emission reduction devices required by regional air quality
regulations. These devices may not need to be used on sites in other areas.
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The TOU also experienced several operational failures and significant amounts of downtime over
the course of the project. Because of the high operating temperatures inside the unit, several
days were required to cool the unit before repair work could be performed, and then at least 24
hours of heating were required to bring it up to operating temperature. Internal components of
the TOU failed in part due to the high humidity in the vapor stream being oxidized. A more
effective vapor condensing system in front of the TOU might have helped to prevent or minimize
these problems. Alternately, a vapor treatment technology less sensitive to moisture could have
been selected for use with the technology.
Other reliability and maintenance problems occurred over the course of the project, including
breakage or malfunction of well headers, hoses, and valves. At the Rainbow Disposal site, two
factors were significant in increasing the amount of system maintenance and repair required. The
installation of all the process wells below grade on the active portion of the facility made it more
difficult to locate problems until they had become significant. Also, the remediation took almost
three times as long as originally planned, so many of the parts had reached the end of their
useful service life before the end of the project.
Because this was the first full-scale application of the technology, it is believed that more
operational problems occurred here than would occur after additional experience has been gained
with the technology. Lessons learned from this application will also assist in minimizing
equipment and operational problems with subsequent systems.
4.4 RESIDUALS
Residuals from the SERF treatment which required disposal or further handling are described
in this section. Drill cuttings were produced every time a borehole was drilled for installation
of process wells or for a sampling event. On the average, two 55-gallon drums of drill cuttings
were generated for each 40-foot borehole drilled using an eight-inch auger. Some sampling
events were conducted with smaller augers, generating fewer drill cuttings. Samples were
collected from each borehole to determine whether the drill cuttings contained detectable levels
-------
of diesel fuel. Uncontaminated drill cuttings were redeposited on the site as fill. Approximately
230 drums of drill cuttings were generated during the technology mobilization, treatment, and
post-treatment sampling. An estimated 40 percent of these drums (92) were considered
contaminated and required off-site disposal.
The effluent from the process wastewater treatment system can also be considered a residual
from the process. Approximately 1.6 million gallons of water were treated by the wastewater
treatment system and discharged to the storm sewer. At a site with some highly regulated or
difficult to treat contaminants, the use of a storm sewer for the discharge of the process
wastewater might not be appropriate. For this case, discharge to a POTW might be an option.
More rigorous on-site treatment, or off-site disposal, might also be necessary for disposing of
the wastewater effluent.
The SERF wastewater treatment system at the Rainbow Disposal site included 5-micron filters
and activated carbon beds, which needed to be replaced when blinded or exhausted. The filters
and carbon were another source of residuals from the system. One change of the carbon beds
was required during treatment, and another at the end of treatment. A total of nineteen 55-gallon
drums of spent carbon were generated from the beds when they were replaced. The used carbon
was sent off-site to be regenerated or landfilled. Regeneration might be the more economical
option, depending on the amount and types of contaminants that the carbon had been removing
from the water. The 5-micron filters were mostly used to remove particulates and colloids from
the water. Depending on the composition of the waste, these filters may or may not be
considered a hazardous waste. The filters would then be disposed of accordingly in a municipal
or hazardous waste landfill.
The SERF technology is designed to remove the contaminants from the soil and concentrate them
for more efficient treatment or disposal. The effluent treatment system includes a gravimetric
oil/water separator to remove most of the diesel from the extraction well liquids. The diesel was
then collected in a storage tank. For this treatment about 4,700 gallons of diesel were collected.
The recovered diesel was sent off-site for disposal or recycling. At other sites, the type of
88
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contamination present in the soil would determine the disposal options for the recovered liquid,
which in some cases could be burned on-site as fuel. The recovered diesel could not be burned
as a fuel at the Rainbow Disposal site due to air regulation requirements.
The oil/water separator also produced small amounts of sludge. This material was periodically
removed, placed into 55-gallon drums, and sent off-site for disposal. Approximately ten drums
of this material were generated during treatment.
The contaminated vapor from the extraction wells was oxidized in the TOU, which was designed
to effect at least 99.99 percent destruction of the organic compounds. The resultant gas stream
contained water vapor and carbon dioxide. This gas was released to the atmosphere through a
stack. A site contaminated with other compounds, especially those containing sulfur or chlorine,
might require further gas treatment.
Solid waste residuals produced from SERF treatment include used protective clothing and
disposable tools. Depending on the contact these items have had with the waste materials, they
can be disposed of as non-hazardous trash, decontaminated, or packaged in drums and sent to
a hazardous waste landfill. At the Rainbow Disposal site, non-hazardous trash could be readily
disposed of by the site owners. Potentially hazardous trash could be disposed of in the same
manner as the contaminated drill cuttings. If it is necessary to remove well casings from the
ground, these materials may also be disposed of as non-hazardous waste if they can be
decontaminated, or as hazardous waste if they cannot be decontaminated.
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SECTION 5
OTHER TECHNOLOGY REQUIREMENTS
5.1 ENVIRONMENTAL REGULATION REQUIREMENTS
Federal, state, and local regulatory agencies may require permits prior to construction and
operation of the SERF technology. 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. Air emission permits may be required for any unit that
could emit a hazardous substance. The Air Quality Control Region may also have restrictions
on the types of process units and fuels that would be used. Local agencies may have permitting
requirements for grading, well installation and abandonment, and health and safety. In addition,
if wastewater is disposed of to the sanitary sewer, then the local water district would have
effluent limitations and sampling requirements. Finally, state or local regulatory agencies may
also establish cleanup standards for the remediation.
At the Rainbow Disposal site, federal and state permits included an ah* permit obtained from the
South Coast Air Quality Management District for the construction and operation of the thermal
oxidation system. The South Coast Air Quality Management District also placed restrictions on
the model of boiler used for steam generation and the type of fuel allowed (natural gas). A
NPDES permit was obtained from the Santa Ana RWQCB for discharge of the treated
groundwater to the storm sewer system, and a Class V Underground Injection permit was
obtained from the USEPA for injection of the steam. No hazardous waste treatment permit was
required since the remediation involved spilled diesel product which is not considered a
hazardous waste.
Local permits included various construction and operation permits from the Huntington Beach
Department of Building and Safety, and permission to operate granted by the local Fire
Department. The Orange County Health Care Agency required permits for the construction and
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abandonment of the groundwater monitoring, extraction, and injection wells. They also requested
to be kept informed about the operations during the remediation activities.
5.2 PERSONNEL ISSUES
Full-scale application of a SERF system will probably necessitate 24-hour per day operation. At
the Rainbow Disposal site, three technicians, a full-time site engineer, and a full-time site
supervisor were required each week during 24-hour per day operation. At least one technician
must be on hand at all times during operation to supervise the function of the boilers and other
equipment. These technicians must be certified in boiler operation by the state in which they are
operating. The technicians and other personnel must also be skilled in maintenance of machinery
(such as pumps and blowers). Training in duties specific to the operation of SERF, such as
collecting temperature data, will need to be performed during process operation.
A part-time secretary was required to order supplies, produce required reports, and handle other
secretarial and administrative tasks. For SERF, Hughes Environmental had a parent company
to which certain administrative duties were directed, and from which came administrative
requirements for items like tirnecards and purchasing; additional administrative staff may have
otherwise been needed.
During sampling events, a geologist and a sampling assistant were required to direct the drilling,
collect the samples, and log the boreholes. Personnel present during drilling on a hazardous
waste site must have current OSHA health and safety certification. Other personnel working on
the site may also need this training, depending on the job description, site layout, and type of
contamination. Personnel who work with hazardous substances or waste must also be enrolled
in a medical monitoring program hi accordance with OSHA regulations.
At the Rainbow Disposal site, the contamination was present below the soil surface. During
typical operations, no contact was made with the contaminated material. Personal protective
equipment for normal work functions included a hard hat and work boots for any personnel
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required to enter the equipment area or the active portion of the Rainbow Disposal site (required
by Rainbow Disposal's Health, and Safety policies). During drilling, digging, residuals handling,
or other activities where contaminated or hazardous materials might be encountered, other
equipment such as chemical resistant gloves and disposable coveralls were sometimes required.
For other sites, the type and use of protective clothing would depend on job function, and
contaminant characteristics and toxicity.
5.3 COMMUNITY ACCEPTANCE
A Visitor's Day meeting was held in March 1992 to distribute information to the public on the
remediation project and on the SITE Program Demonstration of the SERF technology. The
meeting included presentations by the developer and the EPA SITE project manager, and a brief
tour of the site and technology. Participants in the Visitor's Day included regulatory personnel,
remediation contractors, and members of the public. The turnout at the Visitor's Day was high,
indicating strong interest in the SERP technology and its application for remediation at the
Rainbow Disposal site.
The SERP technology works mainly underground, and contaminated soil excavation activities
are minimized. This process limits the potential for human exposure to the contaminants in the
soil, which may make the technology more acceptable to the local community. If the process is
designed and applied properly, the contaminants will be kept within the treatment zone and will
not migrate off-site or vaporize to the atmosphere. The technology is designed to operate more
rapidly than other in situ technologies, thus limiting the duration of the disturbance to site
neighbors. The ability to operate a commercial facility aboveground while the process is
operating belowground can be very important, as was the case at the Rainbow Disposal site.
The process equipment used for SERP, including boilers and compressors, has the potential to
be noisy. This can be somewhat mitigated through choices of equipment and appropriate
installation. Drilling activities required for soil sampling and process well installation can
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produce both noise and dust. These disturbances are for a short duration and can be mitigated
as appropriate to the situation.
Increases in traffic in the area are temporary and would include mobilization and demobilization
of heavy equipment at the start and end of the project, and periodic mobilization of drill rigs.
The technology requires a small crew of personnel for operation, so increases in daily traffic
would be minimal. At the Rainbow Disposal site, the increases in traffic, dust, and noise were
all negligible in comparison with the ongoing trash transfer activities at the site.
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SECTION 6
TECHNOLOGY STATUS
6.1 PREVIOUS/OTHER EXPERIENCE
Technologies similar to in situ SERP have been investigated on a field-scale level at other
contaminated sites. Most notably, a portion of a site contaminated by gasoline to a depth of
about 135 feet was recently remediated with Dynamic Underground (steam) Stripping at the
Lawrence Livermore National Laboratory in Livermore, California. The technology was
successful in removing and recovering a significant portion of the gasoline contamination from
more permeable unsaturated and saturated soil in the test area. Innovative techniques were
applied to monitor the steam zone and control the process. Appendix A to this ITER presents
a case study of the Dynamic Underground Stripping Process.
Since 1985, several small gasoline and diesel spill sites hi the Netherlands have been treated
using similar steam stripping methods [2]. Due to the shallow groundwater in that area, portable
systems utilizing steam lances were used instead of permanent process wells.
At this tune, other tests of steam injection technology are planned at sites contaminated with
dense non-aqueous phase liquids such as trichloroethene. The ability of the technology to
remediate sites contaminated with these denser-than-water compounds, without causing
downward or off-site migration, will be a key evaluation objective for these tests.
6.2 SCALING CAPABILITIES
The SERP technology can be designed, within engineering constraints, to treat a large area to
significant depths. Based on results from the full-scale application of SERP technology at the
Rainbow Disposal site, the critical factor hi scale-up from pilot- or field-scale to full-scale site
remediation seems to be maintaining control of the in situ process. Insufficient subsurface
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temperature monitoring capability over the large treatment area (2.3 acres) and excessive
equipment downtime contributed to inadequate process control and operation and incomplete
remediation at the Rainbow Disposal site. To reduce downtime, major process equipment must
be sized correctly for the full-scale application and must be designed to withstand the corrosion
and wear from long-term treatment.
6.3 OTHER INFORMATION
Hughes Environmental Systems, Inc. operated the SERF technology at the Rainbow Disposal
site; however, they are not vending the technology for use at other sites because they are no
longer in the environmental remediation business. Since SERF uses commonly available process
equipment, the technology can be designed and operated by other consultants knowledgeable in
design and operation of the process. Similar in situ steam technologies may have patented
process or monitoring equipment available only through the developers.
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REFERENCES
1. Udell Technologies, Inc. Field Design for In Situ Recovery of Hazardous Wastes by
Combined Steam Injection and Vacuum Extraction, Final Report, Contract No. DAAL03-
86-D-001. January, 1991.
2. Dablow, John F., III. Steam Injection to Enhance Removal of Diesel Fuel from Soil and
Ground Water. Hazmacon 91.
3. Peters, Max S. and Klaus D. Timmerhaus. Plant Design and Economics for Chemical
Engineers. McGraw-Hill, Inc., San Francisco, 1991.
4. McMaster-Carr Supply Company Catalog No. 96. Atlanta, GA.
5. Lab Safety Supply Inc, 1994 General Catalog: Fall/Winter Edition. Janesville, WI. 1993.
6. Evans, G., Estimating Innovative Technology Costs for the SITE Program. Journal of Air
and Waste Management Association, 40:7, pages 1047-1051. 1990.
7. Converse Environmental Consultants California. Site Characterization, Conducted for
Rainbow Disposal, 17121 Nichols Street, Huntingdon Beach, California. Costa Mesa, CA,
August 11, 1988
8. Telephone communication with John F. Dablow III, formerly of Hydro-Fluent, Inc. January
26, 1994.
9. Isaaks, E.H. & Srivastava, R.M. An Introduction to Applied Geostatistics. New York:
Oxford University Press, 1989.
10. Efron, B. & Tibshirani, R. Bootstrap methods for standard errors, confidence intervals, and
other measures of statistical accuracy, Statistical Science, Volume 1, 1986, pp. 54-76.
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APPENDIX A: Case Study
Dynamic Underground Stripping Process
at Lawrence Livermore National Laboratory
The Dynamic Underground Stripping process, similar to the Steam Enhanced Recovery Process
(SERF), was developed and operated by Lawrence Livermore National Laboratory (LLNL) in
conjunction with the College of Engineering at the University of California, Berkeley. This
process was used to recover gasoline contamination from an underground spill at LLNL. The
process uses steam injection, vacuum extraction, and electrical heating to effect contaminant
removal from soil and groundwater. In addition, underground imaging is used to monitor the
process.
This case study is included here because it presents another application of a technology similar
to SERF with different contamination and geologic conditions. The Demonstration of Dynamic
Underground Stripping at LLNL was conducted and evaluated by LLNL personnel, with limited
participation by the EPA SITE Program. Therefore, this study is only included in this report as
an appendix.
The test site at LLNL was contaminated with leaded gasoline. Gasoline, being more volatile than
diesel, is more readily removed by vapor extraction. Gasoline contamination existed in the
vadose and saturated zones, and in permeable and low permeability soils, at the LLNL site. The
geology of the LLNL test site is alluvial, and is highly variable from location to location.
A full-scale Dynamic Underground Stripping process was used at LLNL. Treatment was
conducted with six injection wells encircling three extraction wells. These wells along with the
EPA SITE Program post-treatment sampling borehole locations are shown in Figure A-l. An
area of roughly 2,000 yd2 down to approximately 135 feet was treated by the process. The
treatment area was significantly smaller than at the Rainbow Disposal site, but the depth of
treatment was much greater. Electrical heating was used to enhance the removal of contaminants
from low permeability zones.
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0'
20'
TEP-GP-106,
(EPA 2) '
HW-GP-105
(EPA 1)
A
A
A
Fence
Truck Scale
Building 406
Concrete
Pad
Gate
Figure A-l. Locations of Ptocess Wells and Sampling Boreholes at the LLNL Site
The maximum total concentration of benzene, toluene, ethylbenzene, and xylenes (BTEX)
recorded in the unsaturated zone before treatment was 4,800 ppm. The volume of soil with
contamination in excess of one ppm of BTEX existed in an approximate cylinder, 60 feet in
diameter, extending down to almost 135 feet.
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Tables A-l and A-2 present the results for the soil samples collected and analyzed by the EPA
SITE Program after treatment with steam and electrical heating was completed. Soil samples
from borehole #105 showed BTEX and Total Petroleum Hydrocarbons (TPH) contamination
below the water table (100 feet). This borehole was located near the original spill point.
Additional contamination was removed by vapor extraction after this sampling episode. Soil
samples from borehole #106 had non-detectable values for BTEX and TPH. This borehole was
located further from the original spill point.
The following document, "Summary of the LLNL Gasoline Spill Demonstration—Dynamic
Underground Stripping Project" presents the LLNL results of the study. These results indicate
that Dynamic Underground Stripping was very effective in removing gasoline contamination
from groundwater and soil in the test zone. As indicated by the EPA SITE Program data above,
this report shows that the process mobilized the contamination toward the center of the test site
and significantly reduced the concentrations of contaminants overall.
There were several reasons why Dynamic Underground Stripping was more successful than
SERP: the contamination had more volatile components, LLNL enhanced the treatment with
electrical heating, LLNL used improved operational procedures, and LLNL used more effective
monitoring of the steam zone for operational control.
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Table A-l. POST-TREATMENT ANALYTICAL RESULTS FOR BOREHOLE #105
Depth (ft)
76.25
82.00
84.25
91.75
96.10
101.55
104.65
109.35
112.05
116.95
122.30
125.30
130.75
135.00
TPH (mg/kg)
ND
ND
ND
ND
ND
ND
ND
21
120
1,400
23
9
ND
ND
Benzene
(mg/kg)
ND
ND
ND
ND
ND
ND
ND
0.8
2.8
13
1.4
0.27
ND
ND
Toluene
(mg/kg)
ND
ND
ND
ND
ND
ND
ND
2.9
12
81
4.2
0.92
0.015
ND
Ethylbenzene
(njg/kg)
ND
ND
ND
ND
ND
ND
ND
0.34
2.3
24
ND
0.18
ND
ND
Xylenes
(mg/kg)
ND
ND
NDX
NDX
NDX
NDX
NDX
2.3X
13X
140X
3.2X
0.91X
0.014X
0.028X
ND - Not detected at or above detection limit.
Detection Limits: TPH-1.0 mg/kg; Benzene-0.0005 mg/kg; Toluene-0.0005 mg/kg; Ethylbenzene-0.0005 mg/kg; Xylenes-0.0010 mg/kg.
X - Estimated value; Continuing calibration values for xylenes failed QC criteria.
Table A-2. POST-TREATMENT ANALYTICAL RESULTS FOR BOREHOLE #106
Depth (ft)
76.25
81.75
87.30
93.85
95.85
100.25
103.80
106.75
109.35
115.35
128.80
130.75
135.00
TPH (mg/kg)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Benzene
(mg/kg)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Toluene
(mg/kg)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Ethylbenzene
(mg/kg)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Xylenes
(mg/kg)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND - Not detected at or above detection limit.
Detection Limits: TPH-1.0 mg/kg; Benzene-0.0005 mg/kg; Toluene-0.0005 mg/kg; Ethylbenzene-0.0005 mg/kg; Xylenes-0.0010 mg/kg.
X - Estimated value; Continuing calibration values for xylenes failed QC criteria.
100
-------
UCRL-ID-120416
Summary of the LLNL Gasoline Spill Demonstration-
Dynamic Underground Stripping Project
R. L. Newmark and R. D. Aines
April 3,1995
This is an informal report intended primarily for internal or limited external
distribution. The opinions and conclusions stated are those of the author and may
or may not be those of the Laboratory.
Work performed under the auspices of the U.S. Department of Energy by the
Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.
-------
DISCLAIMER
This document was prepared as; an account of work sponsored by an agency of the United States Government. Neither
the United States Government nor the University of California nor any of their employees, makes any warranty, express
or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any
information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned
rights. Reference herein to any specific commercial product, process, or service by trade name, trademark,
manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by
the United States Government or the University of California. The views and opinions of authors expressed herein do
not necessarily state or reflect those of the United States Government or the University of California, and shall not be
used for advertising or product endorsement purposes.
This report has been reproduced
directly from the best available copy.
Available to DOE and DOE contractors from the
Office of Scientific and Technical Information
P.O. Box 62, Oak Ridge, TN 37831
Prices available from (615) 576-8401, FTS 626-8401
Available to the public from the
National Technical Information Service
VS. Department of Commerce
5285 Port Royal RcL,
Springfield, VA 22161
-------
Li
Lawrence Livermore
National Laboratory
University of California
Berkeley Environmental
Restoration Center
Summary of the LLNL Gasoline Spill Demonstration
Dynamic Underground Stripping Project
R. L. Newmark and R. D. Aines
Environmental Technologies Program
UCRL-ID-120416
-------
-------
Preface
This report summarizes the four volumes of Dynamic Underground Stripping Project: LLNL Gasoline Spill
Demonstration Report (Newmark, 1994a), which compiles the final reports for all the component activities of
the Dynamic Underground Stripping demonstration at the LLNL gasoline spill site. The demonstration
and cleanup efforts at that site from 1992 to early 1994 were funded jointly by the Department of Energy's
Office of Technology Development and Office of Environmental Restoration. The full report combines
those efforts into sections that reflect the major technical aspects of the project: Summary, Characterization,
Operations, Monitoring, Predictive Modeling, and the Accelerated Removal and Validation (ARV) Project.'
The Dynamic Underground Stripping demonstration at the LLNL gasoline spill site was extremely
successful, and all of the project goals were met or exceeded. All aspects of this project reflect the inte-
gration of complementary technologies and process engineering. Some applications are obvious, such as
the use of electrical heating and steam injection to heat the whole range of soil types. Others are not so
obvious, such as the need to electrically isolate diagnostic and monitoring systems from the tremendous
currents intentionally applied to the ground. The technical challenges in merely fielding these methods
in a safe and effective manner at an operating industrial site were great. Safety in operation was a prime
design parameter; our excellent safety record is one of the most satisfying accomplishments of this pro-
ject. The combined achievements are greater than the sum of each individual component; this satisfies
the requirements of true integration of method and application.
Acknowledgments
The full report, like the demonstration project itself, represents collaboration among investigators
from many organizations, both between LLNL and other agencies and between organizations within
LLNL. In particular, we acknowledge the contributions of Professor Kent Udell and the team members
from the Environmental Restoration Center of the University of California at Berkeley, and the close col-
laboration between these individuals and LLNL researchers. The success of this project was largely due
to the unique field-scale collaboration that utilized the complementary interests and research abilities of
University and Laboratory researchers.
The successful demonstration of Dynamic Underground Stripping at the LLNL gasoline spill site
was made possible through the combined efforts of a great many people, with a broad range of exper-
tise. We acknowledge the efforts of the mechanical and environmental technicians, procurement, con-
struction and plant engineering personnel, and other staff without whose contributions (often in difficult
conditions and inclement weather) this project would not have been possible. Students from the
Environmental Center at University of California-Berkeley also provided essential support.
We gratefully acknowledge the support of the U.S. Department of Energy's Office of Environmental
Management for this demonstration. The demonstration of innovative technologies requires that both
experimental and compliance-driven cleanup operations needs be addressed. The efforts of the U.S.
Department of Energy's representatives to reconcile often conflicting requirements made this project
possible. In particular, we acknowledge the efforts of Clyde Frank, Pat Whitfield, Tom Crandall, Tom
Anderson, Katie Hain, John Mathur, Kathy Angleberger, John Lehr, J. T Davis, Richard Scott, Mike
Brown and Bill Holman. Over its three-year history, this project utilized the resources of mariy, if not
most, of the organizations at LLNL. In particular, we acknowledge the support of Jesse Yow, John
Ziagos, Lee Younker, Bob Schock, J. I. Davis, Ann Heywood, Jay C. Davis, Alan Levy, Walt Sooy, Dennis
Fisher, Harry Galles, Jens Mahler, and Bill McConachie.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence
Livermore National Laboratory under contract W-7405-Eng-48. The UC-Berkeley effort was funded in
part by the National Insrutue of Environmental Health Sciences under grant 3P42E504705.0251.
1 11
-------
The following is a list of contributing authors and their organizational affiliations.
Lawrence Livermore National Laboratory
Earth Sciences Division, Environmental Programs Directorate,-Lawrence Livermore National Laboratory,
Livermore, CA 94550
Roger D. Aines
O. Sierra Boyd
Charles R. Carrigan
Kevin C. Knauss
Kenrick H. Lee
Robin L. Newmark
John J. Nitao
Abelardo L. Ramirez
Jerry J. Sweeney
Defense Sciences Engineering Division, Electronics Engineering Department, Engineering Directorate,
Lawrence Livermore National Laboratory, Livermore, CA 94550
Maurice A. Hernandez
Ray M. McNairy
Engineering Research Division of Electronics Engineering Department, Lawrence Livermore National
Laboratory, Livermore, CA 94550
Jane Beatty
H. Michael Buettner
William Daily
Michael Wilt
Environmental Restoration Division, Environmental Protection Department, Lawrence Livermore National
Laboratory, Livermore, CA 94550
Dorothy J. Bishop
Kenneth L. Carroll
C. Suzanne Chamberlain
Alan B. Copeland
Michael J. Dibley
Paula Krauter
J. C. Nelson-Lee
Maureen N. Ridley
Health and Ecological Assessment Division, Environmental Programs Directorate, Lawrence Livermore
National Laboratory, Livermore, CA 94550
Marina C. Jovanovich
Thomas J. Kulp
Kevin C. Langry
Roger E. Martinelli
Isotope Sciences Division, Chemistry and Material Sciences Directorate, Lawrence Livermore National
Laboratory, Livermore, CA 94550
G. Bryant Hudson
New Technologies Engineering Division, Mechanical Engineering Department, Lawrence Livermore National
Laboratory, Livermore, CA 94550
William H. Siegel
IV
-------
Nuclear Test Engineering Division, Mechanical Engineering Department, Lawrence Livermore National
Laboratory, Livermore, CA 94550
John Carbine
Technical Support and Policy Development Division, Hazards Control Department, Lawrence Livermore
National Laboratory, Livermore, CA 94550
James Martin
University of California at Berkeley
Department of Mechanical Engineering, University of California at Berkeley, 6165 Etcheverry Hall, Berkeley,
CA 94720
Ron Goldman
Kent M. Kenneally
Kent S. Udell
Materials Science and Mineral Engineering Department, University of California at Berkeley, Berkeley, CA
94720
A. E. Adenekan
T. W. Patzek
Oak Ridge National Laboratory
Health Sciences Research Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6113
Tye E. Barber
Walter G. Fisher
Eric A. Wachter
Weiss Associates
Weiss Associates, Inc., Emeryville, CA
Charles Noyes
Everett A. Sorensen
Infraseismic Systems, Inc.
Infraseismic Systems, Inc., 4630 Eastern Drive Suite 5, Bakersfield, CA 93309
Roger J. Hunter
Richard F. Reinke
-------
-------
Contents
Preface
111
Acknowledgments —
Introduction 1
Results of First Full-Scale Test 3.
Based on Three Technologies 2
Steam Injection 2
Electrical Heating ^
Underground Imaging ^
The LLNL Gasoline Spill Site "."!!!!"Z"Z.".".'.'."!! 6
Cleanup Operations 9
Goals of the Experiment 9
Experimental Operations 9
Cleanup Results 26
Free-Product Removal 26
Ground-water Cleanup 27
Ongoing Bioremediation 33
Conclusions from the Gasoline Spill Site Demonstration 34
References 34
VI l
-------
-------
Summary of the LLNL Gasoline Spill Demonstration—
Dynamic Underground Stripping Project
Introduction
Underground spills of volatile hydrocarbons
(solvents or fuels) can be difficult to clean up
when the hydrocarbons are present both above
and below the water table and are found in rela-
tively impermeable clays (Figure 1). Years of
ground water pumping may not completely
remove the contamination. Researchers at
Lawrence Livermore National Laboratory (LLNL)
and the College of Engineering at the University
of California at Berkeley (UCB) have collaborated
to develop a technique called Dynamic Under-
ground Stripping to remove localized under-
ground spills in a relatively short time. The U.S.
Department of Energy's Office of Environmental
Restoration and Waste Management has spon-
sored a full-scale demonstration of this technique
at the LLNL gasoline spill site.
Although it has been known for years that
accumulations of separate-phase organics repre-
sent the most serious cause of groundwater pollu-
tion (National Research Council, 1994; MacDonald
and Kavanaugh, 1994), their very low solubility
in water has made them very hard to remove by
the classic method of pumping out groundwater
and treating it at the surface. Similarly the prin-
cipal natural mechanism for groundwater restora-
tion, biological metabolism of the contaminant,
usually will not work in very concentrated conta-
minant because of the toxic nature of the organic.
(Bacteria typically metabolize organics dissolved
in water, not free organic liquids.)
When highly concentrated contamination is
found above the standing water table, vacuum
extraction has been very effective at both remov-
ing the contaminant and enhancing biological
remediation through the addition of oxygen.
Below the water table, however, these advantages
cannot be obtained. For such sites where the con-
tamination is too deep for excavation, there are
currently no widely applicable cleanup methods.
Dynamic Underground Stripping removes
separate-phase organic contaminants below the
water table by heating the subsurface above the
boiling point of water, and then removing both
contaminant and water by vacuum extraction.
The high temperatures both convert the organic
to vapor and enhance other removal paths by
increasing diffusion and eliminating sorption.
Because this method uses rapid, high-energy
techniques in cleaning the soil, it requires an inte-
grated system of underground monitoring and
imaging methods to control and evaluate the
process in real time.
Results of First Full-Scale Test
We conducted the initial testing of the
combined thermal and monitoring/imaging
methods of Dynamic Underground Stripping
at the site of a gasoline spill at the Lawrence
Livermore National Laboratory. This site was
chosen because several thousand gallons of gaso-
line were trapped up to 30 feet below the water
table (Figure 2), mimicking the behavior of heavy
solvents such as trichloroethylene (TCE).
This first full-scale test of Dynamic
Underground Stripping at the LLNL gasoline site
was extremely successful. Results completed in
December 1993 indicate that the process is more
than 60 times as effective as the conventional
pump-and-treat process now being used at 300
designated Superfund Sites to treat contamination
below the water table, and is 15 times as effective
as vacuum extraction in the vadose zone (above
the water table) (Figure 3). The LLNL site was
previously under treatment by vacuum extraction
from a central extraction well (Nicholls et al.,
1988; Thorpe et al., 1990; Cook et al., 1991).
From August 1988 to December 1991, more than
1900 gallons of gasoline were removed from the
vadose zone. However, the extraction rate had
dropped to about 2 gallons per day by 1991. No
large groundwater removal actions were under-
taken at that point; but because of the low solu-
bility of gasoline in water (about 10,000-ppb total
hydrocarbons were observed in the groundwa-
ter), a pumping rate of 50 gallons/minute would
have only removed about 0.5 gallon of gasoline
per day To continue the cleanup, the vacuum
venting operation was halted, and replaced by
the Dynamic Underground Stripping technique.
-------
Leaking
fuel
tank
Fuel trapped
in silty layer
Figure 1. A plume of organic liquid forming beneath a leaking underground storage tank. This behavior is typ-
ical of a heavy organic solvent such as trichloroethylene (TCE). Some of the liquid may be trapped in layers of
low-permeability soil above the water table. The remainder will form a pool below the water table, as shown
here. Lighter contaminants such as gasoline can be trapped below water by movement of the water table.
During the 21 weeks of operation over the
course of one year, Dynamic Underground
Stripping removed more than 7600 gallons of
gasoline trapped in soil (significantly more than
the 6200 gallons estimated to be present), both
above and below the water table, with separate-
phase contamination extending to >120 ft deep.
The maximum removal rate was 250 gallons of
gasoline a day. The process was limited only by
the ability to treat the contaminated substance
at the surface. Actual field experience indicates
that the process costs $60-$70 a cubic yard.
Approximately 100,000 yd3 were cleaned.
Based on Three Technologies
Dynamic Underground Stripping relies on
three integrated technologies; steam injection,
electrical heating, and underground imaging
(Figure 4).
Steam Injection
Steam is pumped into injection wells, heating
the contaminated earth to 100°C. Steam drives
contaminated water toward the extraction wells
where it is pumped to the surface. When the
steam front encounters contamination, volatile
organic compounds are distilled from the hot
soil and are moved to the steam/ground water
interface, where they condense. Vacuum extrac-
tion after full steaming of the contaminated zone
continues to remove residual contaminants. The
steam injection/vacuum extraction technique was
developed at UCB (Udell and Stewart, 1989, 1990;
Udell et al., 1991; UdeU, 1994d). The steam system
and operational design used here are described
in Siegel (1994) and Udell (1994c). Predictive
-------
160
1-10 ppm
10-100ppm
100-1,000 ppm
>1,000 ppm
Upper steam zone
Lower steam zone
Water table
Screened interval
Sample point
20
0
0 10
Scale : Feet
Figure 2. Cross section showing an approximation of the gasoline contamination at the treatment site before Dynamic Underground Stripping
began. The darker areas represent higher concentrations; the darkest indicates free-product gasoline. The dashed line denotes the level of the
water table. (From Bishop et al., 1994).
-------
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-------
i- Steam
/ injection
{S^t
Typical pattern
Y Vacuum
\extraction
Tomography monitors steam movement
Vacuum
removes
vapor
Condensate
sweeps waste
Tomography images
cleaned areas
Water
table
^ Well to well stripping -1 to 3 months ^
60 to 100 feet
Figure 4. The Dynamic Underground Stripping process. Steam drives contaminated groundwater toward extraction wells and then heats the soil to distill
organics. Electrical heating dries and distills impermeable clays that the steam cannot readily penetrate. Geophysical techniques monitor the process.
The process operates both above and below the water table (dashed line) and is particularly economically attractive for free-product removal (solid green).
-------
calculations of the operational characteristics and
recovery efficiency of steam injection as applied
at the LLNL gasoline spill site are given by Udell
(1994b), Kenneally (1994), Adenekan and Patzek
(1994), and Lee (1994).
Electrical Heating
This technique heats clay and fine-grained
sediments and causes water and contaminants
trapped within the soils to vaporize and be forced
into the steam-swept zones, where vacuum
extraction removes them. Electrical heating is
ideally suited for tight, clay-rich soil and/or near-
surface (less than 20 feet) cleanups. It is an effec-
tive complement to steam injection, because it
cleans the thick, less permeable zones that the
steam does not penetrate well.
Electrical heating has been used in a number
of configurations in enhanced petroleum recovery
(e.g., Chute et al, 1987; Chute and. Vermeulen,
1988); the three-phase system used here was
designed at LLNL (Buettner and Daily, 1994a;
McGee et al., 1994). Details of the electrical
heating construction and operational design used
here are given by Siegel (1994), arid the results of
the preheat phase are found in Buettner and
Daily (1994b). Our predictive and diagnostic
modeling capability for electrical heating is pre-
sented by Carrigan and Nitao (1994). Sweeney
et al. (1994) give details of the post-steam electrical
heating process conducted during this experiment
Underground Imaging
To monitor the Dynamic Underground Strip-
ping process, we used geophysical imaging meth-
ods to map the boundary between the heated
zones and the cooler surrounding areas. Electrical
resistance tomography (ERT) has proven to be the
best imaging technique for near-real-time images
of the heated zones (Newmark, 1992, 1994c;
Ramirez et al., 1993; Vaughn et al., 1993). This
technique is necessary for controlling the thermal
process and for monitoring the water movement.
Details of the use of ERT at the gasoline spill site
are given by Newmark (1994b), and Ramirez et
al. (1994). Tiltmeters provided additional infor-
mation regarding the shape of the steamed zone
(Hunter and Reinke, 1994), while detailed temper-
ature and geophysical logs provided extremely
accurate assessments of the degree of penetration
and the complex heating of the numerous hetero-
geneous formation layers (Newmark, 1994b;
Goldman and Udell, 1994; Boyd et al., 1994).
The LLNL Gasoline Spill Site
We conducted an experimental application of
the Dynamic Underground Stripping technique
during 1993 at the LLNL gasoline spill site. This
is the former site of the Laboratory's filling sta-
tion; fueling operations at this location date back
to the 1940s, when the LLNL site was a U.S.
Naval air station. It is located in the center of an
industrial area—the Laboratory's shipping and
receiving yard. A county road runs along the
south side, and major underground utility lines
run through the site.
Previous characterization results were com-
bined with an extensive set of measurements
taken during the installation of 22. process and
monitoring boreholes at the site. Details of the
site characterization are given in Bishop et al.
(1994). This characterization showed that an
estimated 6200 gallons of gasoline were present
within our target treatment area (both above
and below the water table) (Figure 2). Gasoline
was trapped up to 30 ft below the water table
because of a rise in the water table after the spill
occurred, with the gasoline held below water by
capillary forces in the soil. The soils at the site are
alluvial, ranging from very fine silt/clay layers to
extremely coarse gravels, with unit permeabilities
ranging over several orders of magnitude. There
are two principal permeable zones, one above
and one below the water table, which is located at
100 ft. In between the permeable zones, straddling
the water table, is a 10-15-ft-thick silty/clay layer
of low permeability, which was also heavily cont-
aminated (Nelson-Lee, 1994).
The targeted volume was intended to include
all of the free-phase gasoline at the site, and was a
distorted cylinder about 120 ft in diameter and 80 ft
high, extending from a depth of 60 ft to a depth of
140 ft (Figure 5). Later results indicated that two
small areas of gasoline probably existed outside
the treatment area, possibly from separate spills.
Six steam injection/electric-heating wells
were placed to surround the free product in an
irregular circle determined by the shape of the
free product; three additional electric heating
wells were placed near the center of the spill.
These were not part of the original design, but
-------
Figure 5. Aerial view of the LLNL gasoline spill area, showing regions of known or suspected free-product gasoline contamination (circled). The area is
within the LLNL shipping and receiving yard. East Avenue, a county road, is seen on the south edge of the photograph. Injection wells were sited to
encircle the central plume of free product to ensure that the gasoline would be moved toward the extraction well cluster at the center.
-------
were required when the free-product zone was
discovered to be larger than anticipated during
the drilling of the injection wells. Each injection
well was initially center-punched with a small-
diameter hole for characterization. The discovery
of unexpected free product in two of them had
minimal impact; the holes were completed as
monitoring locations, and new injection wells
were drilled farther from the spill center. We
placed eleven monitoring/imaging wells within
and outside the target area to provide control of
the heating processes (Figure 6).
N
• TEPS •
Perimeter Fence -»
• TEP4 <•> \ *
Well Legend
• Monitcring/Imaging Well
• Steam Injection Well
•f Electrical Heating Well
A Extraction Well
x Soil Sample Well
O Water Monitoring Well
Tiltmeter
OGSW-208
* <•> 1 \ | v-'TEPe*
GIW-818B\ y
TEP-CP-106, \GS^80T \
XX \GEW-710 \ BGIW-820
/ +HW\ \ +HW1
'.TEP9 \ x-SSSSJrf
HW-OP-105 X ^( TEp 10 1^ Liquid Phase
. »r * \ Gasoline
OW-819B/ GEW-808A "GSW-1S l Q ®|
• TEP80:'» ^GSW-16 \ GSW-T1
HW-GP-104 X A i GSB-2 \GIW-«15B
1 GEW -«16 \^ Q •
^ C5W-« O V csz_4 GSW-IA 1
• TFP'J \ TEP 8 M x -tHW3 OGSW-2
" A *-^ -' • * ^V _ -rr-p 7
0 . TEP-GP-103 \ «lhi 7 GSW 216
OGSW-*
Scale
Metere 10 20 30
ill 1
1 1 1 1 | 1 1 1 |
Feet 50 100
GSW-7O
<•>
Figure 6. Map of the LLNL gasoline spill site, showing the location of wells referred to in this summary.
The location of cross section B-B' (Figure 2) is shown. (Not all pre-Dynamic Underground Stripping well
and boring locations are shown.) This map shows a slightly larger area than Figure 5.
-------
Cleanup Operations
Goals of the Experiment
Dynamic Underground Stripping was origi-
nally designed for the removal of separate-phase
organic liquids from highly contaminated areas
both above and particularly below the water
table. The goals of the first application of the
method were:
1. To determine the effectiveness of the
process in removing free product.
2. To evaluate the effectiveness of the moni-
toring methods for controlling heat input and
mapping heated zones.
3. To examine whether any deleterious effects
(such as dispersal of contaminant) might occur.
4. To demonstrate the necessary engineering
and operational practices required for effective
and safe operation of this high-energy technique.
All goals were met and the site and process
were turned over to the Laboratory's site remedi-
ation team (funded by DOE's EM 40) for final site
cleanup (Sweeney et al., 1994).
Experimental Operations
Operations at the site were conducted in four
distinct phases:
(1) Electric Preheating: November and December
1992
(2) First Steam Pass: February 1993
(3) Second Steam Pass: May-July 1993 (drill-back
characterization followed)
(4) Polishing Operations (accelerated removal
and validation): October-December 1993
Table 1 summarizes the project history.
The electrical preheat of the site began in
November 1992, before the treatment facility was
completed. No extraction data are therefore
available from this phase. The electrical preheat
phase is described in detail by Buettner and Daily
(1994b). The 1-MW electrical system operated at
a maximum power output of about 800 kW. The
chief monitoring methods used during the electri-
cal preheating were temperature' measurements
and ERT. Temperatures were measured using
both fixed thermocouples in individual boreholes
and, for continuous logs, an infrared-sensor sys-
tem in the 11 2-in.-diameter fiberglass monitoring/
imaging wells (Newmark, 1994b; Goldman and
UdeU, 1994).
The goal of an average 20°C temperature
rise in the clay zones was achieved; some of the
clay layers were heated to a maximum of 70 °C
(Figure 7). The effects of this phase on the
extraction of gasoline were not tested, but several
of the groundwater monitoring wells on the site
showed increases in the concentration of gasoline
components, indicating that free-phase gasoline
was being mobilized in the vicinity (Figure 8).
Gasoline concentrations in these wells had been
decreasing previously, apparently due to local-
ized bioremediation or venting resulting from the
increased air circulation to the borehole area.
Steam injection began in early February 1993
into the lower of two steam zones (permeable
layers) using a 24,000 Ib/hr (50 gallons water/
minute, energy approximately 8 MW) natural-
gas-fired, skid-mounted boiler (Figure 9). Siegel
(1994) describes the steam operations in detail.
Steam injection rapidly heated the permeable
zones to above the boiling point of water, and ini-
tial steam breakthrough to the extraction wells
occurred in 12 days (Figure 10). During the first
steam pass, it was learned that, although a bank
of cold, free-product gasoline may precede the
steam front to the extraction wells, it contains
only a small fraction of the recovered gasoline
(Jovanovich et al., 1994; Aines et al., 1994)
(Figure 11). None of the 1700 gallons recovered
during the first steam pass could unambiguously
be associated with the liquid front ahead of the
steam. The great majority of the gasoline came
out after a steam zone was fully established, and
the extraction continued without further steam
injection. The reduced vapor pressure forces
residual pore fluids and contaminants to boil.
At this point, the forced boiling generated large
amounts of water and gasoline in the vapor
stream, and our potential removal rates greatly
exceeded our dual-bed activated-carbon trailer's
design limit of about 25 gallons/day. During the
planned shutdown following the first steam pass,
the vapor treatment system was redesigned to
increase capacity (Sorensen and Siegel, 1994).
The monitoring and imaging systems utilized
at the gasoline spill site provided excellent control
of the steam injection process (Newmark, 1994b;
Goldman and UdeU, 1994; Ramirez et al., 1994;
Boyd et al., 1994). Initial steam breakthrough to
the extraction wells occurred in only 12 days;
each subsequent breakthrough occurred sooner as
-------
Table 1. Project history of the Dynamic Underground Stripping project LLNL gasoline spill site cleanup.
Phase
Dates
Objectives
Accomplishments
Vacuum Extraction,
Vadose Zone
EM 40 Operations
9/88 to > Extract vadose gasoline
12/91 contamination.
> Evaluate extraction
effectiveness.
> Pilot Test permitting received.
> 2000 gallons removed
> Biological activity confirmed
Clean Site
Engineering Test
EM 50
2/91 to > Demonstrate
9/91 establishment of steam
zone below water table.
> Evaluate and optimize
monitoring, imaging
systems.
> Optimize resistance
heating electrode
design.
> Evaluate personnel and
environmental safety.
> 10,000 yd-3 steam zone
established below water table
with no steam rise.
> ERT, thermal logging, and
tiltmeters demonstrated, chosen
for gas pad use.
> Individual electrode capacity
raised from 20 kW to 200 kW.
> Safe procedures established for
personnel; no detrimental
environmental effects .
Electrical Pre-Heat
EM50 operations,
EM 40 Treatment
Facility F
construction
11/92 to > Raise temperature of
1/93 clay/silt layers 20°C so
conductivity always
above steam-
temperature gravel
zones.
> Test electrical safety at
high current in
industrial area.
> Optimize electrical
heating methods.
> Clay pre-heating accomplished.
> Maximum heating to 70°C in
clay layer.
> Safety measures and procedures
adequate.
> 850 kW continuous power
achieved.
> Nighttime operations with
daylight construction of
treatment facility.
1st Steam Pass
Joint EM40/EM50
operations
2/93 to > Heat target zones to steam
3/93 temperature.
> Optimize
monitoring/control
methods.
> Evaluate treatment
procedures and facility.
> Quantify possible
deleterious effects
(such as contaminant
spreading).
> Demonstrate safe
handling of steam and
hot gasoline effluent.
> Upper and Lower steam zones
heated to boiling point.
> ERT established as control system
with 12 hr turnaround on 10
planes/day.
> Non-contact thermal logger
demonstrated with no
hysteresis, 100°C/2 ft
gradients.
> Gasoline found to be mainly
recovered in vapor phase,
greatly exceeding capacity. No
liquid phase free-product
recovered.
> No spreading of contaminant to
outer monitoring wells/
> Safe handling of steam and hot
gasoline.
> 1700 gallons gasoline removed.
10
-------
Table 1. (Continued.)
2nd Steam Pass
Joint EM40/EM50
operations
5/93 to > Operate re-designed vapor
7/93 treatment system witn
lOx capacity of first
pass.
> Optimize
steaming/recovery
technique to maximize
vacuum recovery.
> Heat zones which were
insufficiently heated in
first pass.
> Accurately measure
gasoline flux in vapor
and condensate paths,
reduce uncertainty in
total recovery rate,
continuously monitor
gasoline flux.
> 100,000 yd3 heated to boiling
point.
> Recovery rates in excess of 250
gal/day achieved.
> Tiltmeters used for imaging of
horizontal extent of steam
zones from individual wells.
> Most cool zones from 1st pass
fully heated to steam
temperature (one "cold spot"
remained at SO°C).
> Fluxes measured to ± 10 %
accuracy, continuous
monitoring systems
demonstrated.
> 4600 gallons gasoline removed.
Post-Test Drill-Back
Characterization
EM 50
7/93 to > Measure soil
9/93 concentration changes
along six-hole cross-
section
> Ascertain from soil
concentrations whether
spreading had occurred
(outside original
contamination)
> Evaluate process
effectiveness.
> Examine possible changes
to soil.
> Examine effects on
existing microbial
gasoline-degrading
ecosystem.
> Soil concentrations reduced
dramatically.
> No spreading of contaminant;
only inward motion seen.
> Vadose zone completely clean
( Saturated zone contaminant
remained around extraction
cluster only.
> No significant soil changes.
> Active microbial ecosystems at all
locations and soil temperatures
up to 90°C, makeup varies by
soil temperature.
Accelerated
Recovery and
Validation (ARV)
EM 40 Operations
10/93 to
1/94
> Remove remaining free
product, especially in
cool zone.
> Make use of existing heat
and high extraction
rates to continue
removal.
> Electrically heat clay/silt
zones to enhance
removal.
> Test sparging, injection
well extraction.
> Remaining free-product gasoline
removed (1000 gallons).
> Ground water concentrations of 5
of 6 regulated compounds
reduced to MCL.
> Benzene down to 100 ppb in
ground water.
> Sparging monitored with noble -
gas tracers.
> Electrical heating maintained site
soil temperatures during
extraction.
11
-------
Well TEP- 007
0 20
Temperature (C)
40 60 80 100 120 Lithology
40..
50 -I-
Electrical Heating
(1/11/93)
First Steam Pass
(3/11/93)
Second Steam Pass
(6/28/93)
xxxxxxx>
xxxxxxx>
XXXXXXX
XXXXXXX
xxxxxxx>
XXXXXXX'
XXXXXXX'
Clay *+
Gravel
Figure 7. Temperature logs from a monitoring well inside the ring of injection wells, along
with the lithology. These logs show electrical heating of the clay-rich layers during the elec-
trical preheat, steam passing through the most permeable layers during the first steam
pass, and conductive heating of and later penetration by steam into less permeable layers
during the second steam pass. (From Newmark, 1994b).
the formation gained heat. This made the day-to-
day process monitoring critical in order to ensure
that the correct amount of steam was injected to
drive contaminant to the center without adding
excessive amounts of steam outside the pattern.
Each of the twelve injection ports (two each in six
wells) would inject a different cimount of steam at
a given pressure, ranging from 600 Ib/hr to one
well that would apparently have taken the entire
output of the boiler had we so permitted. This
range is expected in such a heterogeneous site,
but it requires that the location and size of the
steam zones be measured in situ, not merely cal-
culated from injection volumes.
Temperature measurements made both with
fixed thermocouples in the field and with the
12
-------
200000
c
o
CO
o
o
150000
100000
o
H
50000
0
After heating
Before electrical heating
I
GSW-006
GSW-001A
GEW-710
Electrical
/ heating
interval
1/1/89 1/1/90 1/1/91 ^-1/1/92 1/1/93
Time
HMB/LLNL/ll-l-93
Figure 8. Chemical signatures of groundwater in monitoring wells in the central gasoline spill area. Before electrical heating, total fuel hydrocarbon
concentrations (TFH) were below 50,000 ppb and generally decreasing, most probably due to localized enhanced bioremediation in the vicinity of the
boreholes. After electrical heating, high TFH concentrations were found, indicating contact with free-product gasoline (Buettner and Daily, 1994b).
-------
Figure 9. Portable steam plant used for the Dynamic Underground Stripping demonstration at the LLNL gasoline spill area. The 24,000 -Ib/hr boiler is skid-mounted;
this particular unit was leased by the month. A steam injection/electrical heating well can be seen in the foreground. Steam is distributed to the injection wells via
flexible rubber hoses. The boiler is fired by natural gas and fed by Laboratory drinking water, both from Laboratory utility lines. An injection well is seen in the fore-
ground, with two injection lines (one for each steam zone). Steam is piped to the wells using flexible reinforced-rubber steam lines.
-------
10
15
Day* (1st Pats)
20
25
30
35
40
1004-
80
60
I
«
40 •
20 -
Calculated
Boiling Point
Pumped
Water
Temperature
Well 808 Vapor
Temperature
Temperature At
Recovery Wells
2/3/93
2/8/93
2/13/93
2/18/93
2/23/93
2/28/93
3/5/93
3/10/93
Date
Figure 10. Extraction well temperatures during the first steam pass. Steam breakthrough to the extraction
wells occurred about 12 days after steam injection began in the lower steam zone. Calculated boiling point
based on the vacuum applied to the well. (After Aines et al., 1994).
continuous temperature loggers showed a rapid
temperature rise in the more permeable zones
(Figures 6 and 12). The temperature logs
revealed thermal gradients of up to 100°C over
just a few feet depth during initial steam injec-
tion, and provided the most accurate measure-
ments of the vertical distribution of the steam at
the 11 locations (Newmark, 1994b; Kenneally,
1994).
Between the wells, ERT proved to be a rapid
and accurate way to map steam progress at 1-2-m,
resolution, providing actual images of the heated
zones by comparing the electrical resistance dis-
tribution before heating to that afterwards
(Ramirez et al., 1994) (Figure 13). Daily ERT
images showed the vertical extent of the steam
zones and the lateral movement between imaging
wells. They revealed a number of areas where
steam was moving vertically in the formation that
were not detected by the temperature logs in
individual wells. The total cycle time to obtain
and process the data for each image was about
an hour. This made ERT the principal control
method, and decisions on steam injection rates
made at the morning operations meetings were
based principally on ERT images from the previ-
ous day. Coupled with the temperature profiles
from the continuous temperature loggers, steam
15
-------
S.
total
carbon trailer
liquid megaton-
aqueous
2/3/93
3/10/93
Figure 11. Daily average gasoline recovery rates during the first steam pass. (From Udell, 1994a,c).
progression through the formation was seen to
occur in multiple horizontal pe:rmeable zones,
with significant vertical motion occurring in some
areas. The combined ERT/temperature 2-in.
fiberglass wells were placed to allow optimal
monitoring of the interior of the treated zone
(extending about 30 ft outside the ring defined by
the steam injection wells) and lower-resolution
monitoring of the surrounding area. Induction
logs run in the monitoring wells revealed the
changes in the electrical properties of the heated
soils in detail. These results were used to calcu-
late fluid saturation in the steamed zones (Boyd
et alv 1994) (Figure 14).
An array of tiltmeters was installed near-
surface in a double ring surrounding the site to
monitor the lateral extent of the steam zone out-
side the treated area (Hunter and Reinke, 1994).
The array was used in two modes: passive and
active.
In the passive mode, tiltmeters measure the
small deformations in the ground surface that
result from a subsurface pressure transient in
terms of tilt. As the steam front moving in the
subsurface approaches a tiltme ter, it produces a
pressure transient and causes the ground to
deform. If the signal is sufficiently large, the tilt-
meter will detect the slight tilt resulting from that
pressure transient. Using this method, we
mapped the outer extent of the steamed region
during steam injection.
In a more active mode, the tiltmeter array
was used to measure the slight deformation in the
ground surface resulting from a pressure tran-
sient induced into the steam zone by shutting off
an injection well for a fixed time. Maps of the
areal extent of the steam zone emanating from
each well could then be obtained, particularly for
the lower steam zone (located below the pre-
steam water table). This technique was extremely
effective in mapping the lateral spread of steam
and the development of any preferential steam
pathways.
During the first steam pass, tiltmeters were
primarily relied upon to delineate the outer
extent of the steam front. We tested and validat-
ed the processing technique whereby the individ-
ual steam zones could be mapped during this
pass, where the subsurface monitoring network
of temperature measurements and ERT image
planes could provide ground truth.
The second steam pass was begun after a
3-month hiatus to redesign the effluent treatment
capacity, establish better analytical control on the
effluent stream based on our new knowledge of
the comparative flows in vapor and water, and
evaluate the cost-effectiveness of the process. In
this pass, we optimized the amount of time the
formation was kept under vacuum (no steam
injection) and greatly increased the extraction
rate, hitting a contaminant recovery peak of more
than 250 gallons/day and routinely removing
more than 100 gallons/day (Figures 15 and 3).
The focus of the various monitoring activities
was somewhat different during this pass, where
steam was being injected into previously heated
soil. Although the ERT images continued to pro-
vide valuable information, interpretation was
16
-------
CJ
CD
120
TOO
80
60
Q.
E
0)
20
0
First Steam Pass
Second Steam Pass
ARV Phase
Ground water pumping
" Electrical Preheat
Electrical Heating
O ^r* ""C*
>Jy eP ^»
-50 0 50
V
-------
TEP8
TEP9
00
silts & clays
inter bedded
sands, silts
fit gravels
silts & clays
permeable
sands,
silts & clays
Absolute Image
Resistivity {log ohm rn)
\
Iniectlon wells
1.7
ft m
TEP8
Day 1
Day 2
Day 4
Day 12
uay ID
Day 36
TEP9
Resistivity change (ohm m)
-30.0
Figure 13. Electrical Resistance Tomography (ERT) images. Top: ERT absolute images reveal the continuity of soil units across image planes. The resistive units correspond to the more
permeable sand and gravel zones; the conductive units correspond to the clay-rich intervals. (The apparent pinching-out of units in the center of the image is due to the increase in resolu-
tion radius toward the center of each image). Bottom: ERT difference images show the progress of the steam fronts across the image plane, starting from the first day of steam injection.
This image plane (between wells TEP 8 and TEF 9) is located approximately 6 m from the nearest injection well, and is oriented nearly perpendicular to a line linking it and the extraction
wells. Small decreases in electrical resistivity are observed within hours of the start of steam injection. Although steam was initially injected into only the lower steam zone (centered at
about 35-in depth), steam leaked into the upper steam zone (centered at about 25-ni depth) through the well completion in the nearby injection weil; this is evidenced by the resistivity
decreases in both zones in these images. By the end of the first steam pass (Day 36), both the upper and lower steam zones were at or near steam temperature, with conductive heating
occurring in the neighboring day-rail units. The preferential steam paths closely follow the more resistive units seen in the absolute images. (Frout Newuiark, 1994b).
-------
o ••
•s
Q.
&
10
15 •
20
25'
30'
35 '
40-
45 '
Lithology
W////.
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5 "
10 '
15 •
20 '
25 '
30
35 '
40-
45
TEP 5
Resistivity (ohm-meters)
5 10 15 20 25 30
0
0 -
5 •
10 •
15
20 -
25
30
November 4, 1992
^ \ ^July 19, 1993 40
February 24, 1993
45 -
50
Temperature (degrees C)
20 40 60 80 100
—I 1—
J
k
July 19, 1993
February 24, 1993 2
r
Figure 14. Induction logs such as these obtained in well TEP 5 reveal the changes in soil electrical properties in detail. In the baseline log (11/4/92, solid curve), the permeable zones
have high resistivity. During the first steam pass (2/24/93, dashed), the narrow heated zone at about 35 m displays lowered resistivity. After the second steam pass (7/19/93, dotted),
a broad zone from about 15-40 m exhibits both elevated temperatures and diminished resistivity. The narrow aquifer at 35 m has experienced groundwater recharge; hence, its
resistivity is indicative of heated saturated conditions compared to the hot, dryer conditions existing during the first steam pass. (From Boyd et al., 1994; New mark, 1994b).
-------
condensed
aqueous
5/24/93
5/31/93
6/7/93
6/14/93
6/21/93
6/28/93
7/5/93
Date
Figure 15. Daily average gasoline recovery rates during the second steam pass. (From Udell, 1994a,c).
N
A Injection well
0 Extraction well
© Tiltmeter
June 2,1993
Figure 16. Tiltmeter maps show the growth of the team fronts emanating from two injections wells on con-
secutive days. At this time, steam was being injected into only two wells, below the water table. Steam
broke through to the extraction wells the third day. (From Hunter and Reinke, 1994).
20
-------
and "sweep" the steam across the remaining cool
areas. The pulsed mode of operation, alternating
steam and vacuum-only on a 5-6-day cycle, was
very effective at maximizing contaminant
removal. We terminated this phase on schedule
on July 9,1993, while the extraction rates still
ranged between 50 and 100 gallons/day.
Evaluation of the gasoline concentration in
the effluent from the extraction \vell proved diffi-
cult in the first pass, but was significantly
improved in the second pass (Jovanovich et al.,
1994; Aines et al., 1994). Most of the gasoline was
removed in the vapor phase, and much of that
was condensed along with a large amount of
water in the heat exchanger (Ain.es et al., 1994).
The second-pass addition of an oil-water separa-
tor on this part of the effluent stream allowed an
accurate determination of the condensed part
of the flux by simple volume measurement
(Sorensen and Siegel, 1994). The remaining dried,
cooled vapor was burned in two internal combus-
tion engines; the flux of gasoline in this stream
was highly variable, as a function of the amount
of steam in the injection wells, total vacuum
applied, and time of day (temperature of the heat
exchanger).
Because of the cost and hazards associated
with sampling and analysis, off-line vapor sam-
ples were collected only once or twice daily. This;
sampling frequency provides somewhat limited
insight into the Dynamic Underground Stripping
process, and cannot provide sufficient data for
detecting short-term fluctuations in system per-
formance or for real-time optimization and
control of the system.
We employed a series of continuous in-line
chemical sensing systems to measure this flux
and to allow the same level of control for the
chemical extraction rate as was obtained for the
thermal injection systems. These included a stan-
dard Fourier-transform-infrared (FT-IR) spec-
trometer equipped with a gas sample cell, an
automated gas chromatograph (with photoioniza-
tion detector), and the experimental Differential
Ultraviolet Absorption Spectroscopy (DUVAS)
system. The trends indicated by the in-line sen-
sors were in agreement with standard off-line lab-
oratory analyses, and were obtained continuously
in near or real-time (Figure 17a).
Continuous monitoring allowed transient
events and mid- to long-term trends in the
extraction process to be measured. For example,
the DUVAS data showed significant diurnal
fluctuations in the absorption of total aromatic
compounds; these fluctuations corresponded with
recorded variations in ambient temperature and
changes in the pressure and flow rates within the
vapor extraction system (Barber et al., 1994a,b)
(Figure 17b). The correlation between ambient
temperature and sensor response led to an
analysis of the vapor system's efficiency. The
fluctuations appear to be caused by changes in
condensation efficiency resulting from variations
in ambient temperatures (higher condensation
rates during the cooler nighttime temperatures.)
This explanation also resolved the apparent scat-
ter between the contaminant concentrations
measured in the morning and afternoon vapor
samples. (The morning values showed signifi-
cantly lower concentrations than the afternoon
samples.) Thus, the in-line sensors, due to their
high sample frequency, revealed trends that
occurred between samples and provided a
context in which to interpret the analytical
results.
During the second steam pass, about 5000
gallons of gasoline were recovered. Extraction
rates were extraordinarily high at the beginning
of the second pass because of the 3-month heat
soak of the formation and the accompanying
release and volatilization of gasoline (Aines et al.,
1994).
By the end of the two steam injection phases,
most of the soil within the treatment volume was
heated to the boiling point of water. Only the
thick clay layer at 95 to 110 ft in depth did not
reach this value, in places reaching only 80°C. It
was within this "cold spot" that the largest con-
centrations of gasoline remained (Figure 18).
Drill-back characterization utilizing six bore-
holes in a line across the spill site after these first
two phases indicated that, as expected, there was
still free-product gasoline in the vicinity of the
extraction wells but that it was now restricted to a
small area just below the water table (Figure 19).
Based on the observed soil concentrations, it was
estimated that about 750 gallons remained in the
clay unit. Gasoline had been substantially
removed from the edges of the spill and from the
vadose zone.
Of significant importance to this experimental
application of Dynamic Underground Stripping
was the finding that gasoline concentrations were
not increased in the soil outside the treatment
volume. However, groundwater and vapor gaso-
line concentrations were still very high.
At this point, operational control of cleanup
activities at the gasoline spill site was transferred
21
-------
OH
D-
CQ
d
600
500-
400-
30CH
200-
100-
Laboratory
14 ' 16 ' 18 ' 20 ' 22 24262830323436384042444648
Total Days of Operation
Total Aromatics
14
24 26 28 30 32 34 36
Total Days of Operation
38
40
42
44
46 48
Figure 17. (a) Comparison of the benzene concentration measured by DUVAS and off-line laboratory analy-
ses, (b) Observed variations of relative total aromatic concentration from DUVAS, extraction line vacuum,
and vapor temperature. (From Barber et al., 1994a).
22
-------
N>
CO
ft m
50-T1 5 20
70 ~
TEP 8
TEP 2
Data for 3/11/93, end of first steam pass
resistivity change ohm m
-30.0
0.0 5.0
Figure 18. ERT and temperature surveys detected a "cold spot" after the first steam pass. Data from March 11,1993,
at the end of the first steam pass, reveal a zone between about 32 m and 37 m where temperatures have not risen much
above ambient. The ERT images indicate the lateral continuity of this zone between wells in which temperatures can be
measured.
-------
20
40
60
£ 80
Q.
0)
0
100
120
140
160 L
in
o
OCN,
if
9
I
CO
o
Ground surface
1-10 ppm
10-100ppm
100-1,000 ppm
>1,000 ppm
Upper steam zone
Lower steam zone
Water table
Screened interval
Sample point
20
0 10
Scale: Feet
Figure 19. Approximate cross section of the treatment site from the characterization drill-back after the two steam passes (compare with Figure 2). The area
of gasoline contamination has contracted greatly, and there are no indications of free product remaining in the treated area outside the volume immediately
around the extraction wells. No gasoline has been dispersed outside the treated volume. (From Bishop et al., 1994).
-------
from the more experimental Dynamic Under-
ground Stripping demonstration team to the
LLNL site cleanup organization. Subsequent
activities focused on the final cleanup of the site.
Extraction of groundwater and vapor
resumed as part of the Accelerated Recovery and
Validation (ARV) project (Sweeney et al., 1994) in
October 1993; the spike in initial extraction rates
was smaller than observed after the first pass
(Figures 20 and 3). Electric heating was applied
to the system in November. Approximately 1000
gallons were removed during this phase, with the
concentrations and extraction rates falling dra-
matically. Electric heating raised the overaD
temperature of the treated zone only slightly,
apparently because the extraction systems were
removing large amounts of heat (50 to 100 kW) at
the high temperatures prevailing at the time.
When the extraction systems; were turned off,
temperatures in the clay zones began rising
(Figure 21). The electric heating was terminated
on December 16, and the system was shut down
for the holidays. At this point, at least 7600 gal-
lons of gasoline had been removed from the site.
The discrepancy between this and the 6200 gal-
lons estimated to be present is not surprising
due to the extreme heterogeneity of the site
and the difficulty in characterizing gasoline
trapped in soil capillaries. Historically, very few
measurements of total hydrocarbons were made
at the site, since measurements of BTEX (benzene,
toluene, ethylbenzene, and xylenes) were suffi-
cient to delineate the contamination and quantify
the regulated contaminants (Dresen et al., 1986).
The error in converting the BTEX measurements
to total gasoline is therefore fairly large, and the
estimated total volume of gasoline subject to an
error of several thousand gallons (Devaney, 1994;
Aines et al., 1994).
In January 1994, groundwater pumping and
vapor extraction resumed. During the 1-month
shutdown during the 1993-1994 year-end-break,
concentrations in the vapor increased only slightly,
and water concentrations decreased. Benzene
concentrations in the extraction wells continued
their downward trend, now at less than 200 ppb
from a peak of 7000 ppb before the start of steam
injection. At a groundwater monitoring well
within the pattern, benzene concentrations have
decreased dramatically, from several thousand
parts per billion before Dynamic Underground
Stripping to less than 30 ppb in January 1994.
Other wells show similar decreases. These factors
indicate that there is no significant free-phase
gasoline remaining in the treatment volume,
although significant contamination may still lie
outside the treatment volume.
W000000000000000000ff0i
11/15/93 11/22/93 11/29/93
total
burned
condensed
aqueous
10/4/93 10/11/93 10/18/93 10/25/93
12/6/93
Figure 20. Daily average gasoline recovery rates during the ARV phase. (From Udell, 1994a,c).
25
-------
o>
CO
I
0>
t
o>
H-
100
90
80
70
60
50
40
30
20
Tc 2 (33.5 m, gravel)
•s i lm n
^^^^^^^^F"^^^^_.^^^M_ai^^fc
Tc 3 (29 m, sand)
Tc 4 (24.4m, silt)
Tc 1 (39.6 m, sand)
Pumps Pumps
.off/.../on
320
Heating begins
fi 111 ft.i 1111111^
330 / 3AGT
/ Pumps/
ins ' Off
Z Heating ends
.1.........1
350
360
370
Julian day
Figure 21. Fixed thermocouples in well TEP 2 show different responses to electrical heating during the ARV
phase. Slight temperature rises occur hi sandy or silty zones, even while the extraction systems were remov-
ing heat from the system. The two lower thermocouples (Tc 1 and 2, open symbols) are located below the
standing water table. The two thermocouples above the water table (Tc 3 and 4, dosed symbols) show tem-
perature rise throughout electrical heating. (After Sweeney et al., 1994).
Cleanup Results
Free-Product Removal
Free-product gasoline has been removed from
the treated area at the LLNL gasoline spill site,
thus accomplishing the goal of Dynamic
Underground Stripping; approximately 7600 gal-
lons of gasoline were removed from above and
below the water table. This conclusion deserves
careful scrutiny because of the previous great dif-
ficulty in accomplishing this goal experienced by
other cleanup methods.
The bases for this conclusion are:
1. 6200 gallons of gasoline were estimated to
be in the treatment zone, and 7600 have been
removed. After the August 1993 drill-back, soil
concentrations indicated that 750 gallons
remained (if the distribution was symmetric).
Over 1000 gallons have since been removed.
Extraction rates fell to nearly zero (11 gallons per
month) in January 1994 and have remained low.
2. Groundwater concentrations in the extrac-
tion wells and in the two available monitoring
wells inside the pattern (GEW 710 and GSW 1A)
are lower than the apparent solubility of the most
recently extracted gasoline. Although the solubil-
ity of gasoline can vary greatly depending on its
composition, by measuring the concentration in
the water in the oil-water separator where raw
26
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gasoline is known to be in contaict with ground-
water (Jovanovich et alv 1994; Sweeney et al.,
1994), an accurate estimate under site conditions
can be obtained. The equilibrium concentrations
currently are >35,000 ppb at 20°C; groundwater
samples from the extraction and monitoring wells
are less than 10,000 ppb at elevated temperatures
(>50°C). These are well below the initially
observed values for water in contact with free
product when wells were drilled (40,000-70,000
ppb), and an order of magnitude? below the
values observed in the monitoring wells after
electrical heating mobilized gasoline (120,000—
180,0000 ppb).
3. Vapor and liquid concentrations did not
rise significantly after the December 1993-January
1994 shutdown period. Previous shutdowns with
hot ground resulted in large increases in concen-
tration when the treatment system was turned on
again. Presumably, this was due to the mobiliza-
tion and/or vaporization of free-product gaso-
line. The absence of such a pulse after ARV indi-
cates that there was no free product remaining.
4. Groundwater concentrations of BTEX at
the central extractors are at lower values than the
initial groundwater concentrations just outside
the injection ring (e.g., GSW 2, 3,13), and are at
comparable concentrations to many of the distal
wells (see below).
The limitations to the conclusion that we
have removed all the free product are:
1. Our ability to resolve the presence of free-
product pockets by chemical means is limited by
the degree of contact with flowing air or water.
This is difficult to quantify.
At the start of ARV, the remaining gasoline
left a chemical signature of 20,00(3 ppb total petro-
leum hydrocarbons (TPH) in groundwater, which
dropped to 10,000 ppb by the end of the ARV
phase (Sweeney et al., 1994). During ARV, about
1000 gallons of gasoline were removed. This
places an upper limit on the free product remain-
ing in the treated area today, based on ground-
water analysis alone of 1000 gallons.
There are approximately 1 million gallons
of groundwater in the near vicinity of the extrac-
tion wells. Given the observed concentrations of
TPH during the ARV phase, this places a lower
limit of 10-20 gallons (dissolved in groundwater).
This indicates that there are much less than 1000,
but possibly on the order of tens, of gallons of
gasoline remaining (99.9% removal would cor-
respond to about 10 gallons remaining). Any
pocket of free product near the extraction wells
would have to be extremely well isolated from the
permeable parts of the formation to have survived.
2. Free product may remain in the area out-
side and east of the treated area (e.g., near GSW
216). The vapor concentrations in the eastern-
most injection well (GIW 815) are still fairly high
(Sweeney et al., 1994). This may be due to either
free product in the area or from the vapor being
pulled in from the area to the east. It is more like-
ly that this results from vapor being pulled in
from the east; if there were free products in the
area, we would have seen this in the GSW-001A
results. In addition, there was a pocket of free
product under the receiving yard to the north of
the treatment area before Dynamic Underground
Stripping was begun. This was sampled during
the drilling of TEP 5 (Bishop et al., 1994).
Groundwater Cleanup
Cleanup of groundwater is the goal of any
remediation effort, so the results of the LLNL
demonstration must be measured principally in
terms of the resulting contaminant concentrations
in the water beneath the site even though the
goals of the project were strictly limited to free-
product removal. The regulated contaminants 1,2
dichloroethane (DCA), xylene, and toluene are at
or near their allowed Maximum Contaminant
Limit (MCL) in the groundwater of the treated
area. Benzene has been reduced dramatically,
although it is still well above the MCL (Table 2,
Figure 22).
Table 2 gives average values for the major
regulated contaminants in the central region of
the gas pad; this requires the use of data from
several wells, as noted. Dynamic Underground
Stripping went far beyond free-product removal;
it lowered the benzene concentrations inside the
central region to levels below those observed out-
side the treated area (the so-called bathtub ring of
untreated but slightly contaminated water)
(Figure 23).
Concentrations of 1,2 DCA have dropped to
below detection limits in the treated area, and are
significantly reduced in the surrounding region.
Xylene concentrations are diminished in the
treated area. The increase in xylene concentration
in GSW 216 (east of the treated area) probably
reflects the local mobilization of gasoline compo-
nents through increased solubility and decreased
sorption due to heating (Figure 8).
27
-------
Table 2. Average level of contaminant in central extractors.
Data iBanzana 1.0 ppb
1987
1999
1990
1992 (Pr«-OU3)
1999(Av«rag«DUS)
12/99 (Poat-DU8)
1/94
i/94
9/94
9/94
9/1A1994
Av*rag* of w«4la
outolda treated araa,
ppb
6400
4600
1705
3646
2081
286
170
125
157
172
200
385
1992*
ratio to md -1
0399
4599
1704
3645
2080
285
169
124
156
171
208
384
iToluaiM 100 ppb IXytanaa (1750 ppb)
ppb
4900
4220
1500
2187
4143
804
683
150
257
177
189
3
ratio to md -1
46.0
412
14.0
20.9
40.4
7.0
5.8
0.5
1.6
0.8
0.9
•1.0
PPb
2800
2940
1643
2935
3810
1725
1866
846
327
530
448
6
ratio to md -1
0.6
0.7
•0.1
0.7
1.2
0.0
0.1
•0.5
-08
•0.7
•0.7
•1.0
11.2 OCA (1.0 ppb) |EttivlbanzafM(680ppb) 1
ppb
200
118
188
117
0
0
0
0
0
0
0
72
ratio to md -1
399
235
375
233
-1
-1
•1
•1
•1
-1
•1
143
ppb
360
360
305
838
684
88
36
7.7
26
2
6
5
ratio to md -1
-0.5
-0.5
-0.6
0.2
0.0
•0.9
•0.9
-1.0
-1.0
-1.0
•1.0
-1.0
•Notes: 1987 GSW 15 value from 12/15/87
K>
0° 1988 average of values from GSW-015 in 1988
1990 average of tests of GSW 16 11/6 -12/14/90
Data for GSW 001A for DCA only, 1990
1992 Avenge of GEW 816 tests, about 8/15/92
1993 Average of all values observed at SEPI port during second pass operations (from Jovanovich et al., 1994)
12/93 LLNL Lab data sampled 12/6/93 , GO-018. UVI port (although SEPI is consistently about 20% higher)
1/94 Data from LLNL ERD GM-071 sampled 1/19/94, data from UVI port (uncorrected for SEPIAJVI differences if any)
3/94 LLNL lab data GO-091 sampled 3/10/94, UVI port
6/94 LLNL data GP-037 sampled 6/14/94, UVI port. After about 1 month at total shut down.
8/94 LLNL data OP-096 sampled 8/1/94, UVI port
LLNL data GP-125 sampled 9/1/94, UVI port
Outside wells: Average of 1992 values for GSW 8,10,208,216 (wells well outside the treated area that had gasoline contaminant)
-------
6399
399
Benzene
MCL=1.0 ppb
6/94
,7000
1,2 DCA
MCL=1.0 ppb
400
300
h200
o
15
_j
O
100
3/94
6/94
Non Detect
C'<>e--- Ho
i
50
48.0
Toluene
MCL=100ppb 50°
0.6
5.0
Xylenes
MCL=1750 ppb f40
Figure 22. Dissolved groundwater contaminants at the gasoline spill site through June 1994. MCL ratio is expressed as [(contaminant concentration (ppb))/
(MCL (ppb))] - 1. The ratio is zero when the MCL is reached, and drops to negative values (as shown for xylene) when the MCL is exceeded. Values are given
for the central extraction wells (GSW 15,16 and GEW 808,816). Starting and ending ratios are noted. In June, 1,2 DCA and total xylenes were below MCL,
as were ethylbenzene and ethylene dibromide (not shown). Toluene was at 1.6 above its MCL, and benzene was 156 times its MCL. Data from Table 2.
-------
Figure 23 Comparison of MCL ratios observed at seven monitoring or extraction wells before Dynamic Underground Stripping (1992 average values) and after the
ARV phase (January 1994). Clockwise from the central extraction wells (GEW 808 and 816) are GEW 710, GSW 208, GSW 216, GSW 7, GSW 8, and GSW 1 (at
center of photo) (Figure 6). Free-product gasoline was observed in GSW 216 when it was drilled in 1986 (Dresen et aL, 1986). (a) Benzene.
-------
u
Q
31
-------
Ratio of ground Waier
concentration io;$jpj^*|t*
MCL before and after Sf
Dynamic Stripping
After
(c) Total xyienes.
-------
Concentrations in GSW 1 appear higher in
the treated area; this value roughly matches the
levels seen in the extraction wells, and reflects the
same mobilization mechanisms. Ethylbenzene
and ethylene dibromide are below the MCL as
well.
Contaminant concentrations in the central
extraction wells appear to approach the outside
well values, indicating that water in the treated
area is equilibrating with the untreated water as
the extraction system draws water in.
The ability of Dynamic Underground
Stripping to remove contaminants to such low
levels in groundwater is probably indicative of
the boil-off distillation mechanism described by
Udell (1994a). Because volatile components are
generally removed from boiling; water at a mass-
removal rate exceeding that of the water, boiling
of a small percentage of the pore water can dra-
matically reduce aqueous concentrations.
Udell examines the effect as a function of
boiling rate, solubility, and Henry's law constants;
unfortunately, solubility and Heinry's law con-
stants are not known at high temperatures for
most groundwater contaminants (see data for
xylene obtained as part of the ARV activities,
Sweeney et al., 1994). This mechanism may be
responsible for the almost instantaneous removal
of 1,2 DCA from the gasoline spill site ground-
water by Dynamic Underground Stripping and
the dramatic decrease seen in benzene relative to
xylene.
Ongoing Bioremediation
Before Dynamic Underground Stripping
treatment of the gasoline spill area, a wide variety
of microorganisms were actively degrading the
BTEX components of the gasoline. These organ-
isms included the dominant genus Pseudomonas
originally, and after a campaign of vacuum vent-
ing in 1990-92, the genus Flavobactor was domi-
nant. The largest populations otisted in areas
where gasoline was present at low concentra-
tions. In the capillary fringe zone (up to 5 ft
above the water table) where gasoline concentra-
tions were highest, there were low numbers of
culturable organisms. In the central area of the
spill, below the water table, oxygen concentra-
tions were very low, and microbial activity was
effectively zero.
Extensive characterization of the microbial
population was conducted before heating the
area, with the expectation that the soils would be
sterilized and the population rebound of microor-
ganisms in the area could be studied. Post-test
drill-back in August 1993 included collection of
extensive soil samples that were cultured for
microorganisms both at room temperature and at
50°C.
Although the gram-negative bacteria that had
been the dominant BTEX degraders were gone,
extensive microbial communities were flourishing
in all samples, including those in which the soil
was collected at temperatures greater than 90°C
The dominant species were no longer bacteria,
but yeasts and related organisms (Rhodotorula,
Streptomyces], which had been observed in small
numbers before heating. Thermophiles previous-
ly identified from environments such as the hot
springs at Yellowstone National Park are impor-
tant members of the new community, as well as a
number of other organisms apparently represent-
ing previously unidentified species.
The rates at which this new biological com-
munity are degrading gasoline components has
not yet been quantified, but it is clear that BTEX
degraders (e.g., Rhodotorula) have survived and
can rapidly undertake the final removal of conta-
minants from the groundwater. At this point, the
addition of trace nutrients to the system is being
considered to enhance this activity. It is hoped
that final reduction of benzene levels to below the
MCL of 1.0 ppb can be accomplished through a
combination of continued intermittent operation
of the groundwater and vapor extraction systems
to provide oxygen, and proper encouragement of
the microbial ecosystem.
33
-------
Conclusions from the Gasoline Spill Site Demonstration
• Separate-phase gasoline has been removed
from the treated area.
• A stable steam zone can be established
below the water table.
• Steam injection is effective for heating per-
meable zones, and repeated steeim passes can
effectively heat small impermeable layers
between.
• Dynamic Underground Stripping can
reduce groundwater contamination to very low
levels.
• Electrical heating is effective for heating
clay zones, but higher power levels are required
when extraction of hot fluids is removing heat
from the formation.
• Establishing a complete steam zone in very
permeable materials requires large amounts of
steam; the more the better.
• Electrical resistance tomography is
extremely sensitive to heating of soil and gives
rapid images of steam movement between wells.
• Tiltmeters accurately mapped the outer
extent of the steam fronts both above and below
the water table, and the footprint of steam zones
emanating from individual injectors in the lower
steam zone.
• Steam did not displace much liquid conta-
minant in a piston flow.
• Vapor recovery is the major contaminant
removal mechanism.
• Gasoline is locally mobilized in heated
areas and may show higher groundwater concen-
trations outside the treatment area even though it
is not being transported.
• Treatment systems must be robust to han-
dle the large peak extraction rates and the rapid
changes in rate.
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